Sofia Tseleni-balafouta | National & Kapodistrian University of Athens (original) (raw)

Papers by Sofia Tseleni-balafouta

Journal of Clinical Oncology, 2009

To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's ly... more To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's lymphoma (NHL) with serum adiponectin and leptin levels in a nationwide case-control series. In addition, expression of adiponectin receptors in NHL specimens was assessed, and the association between adipokines and childhood NHL survival and prognosis was examined.

Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin r... more Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin receptor expression has not been examined in normal gastrointestinal tissue, colorectal malignancies, or gastrointestinal stromal tumors (GISTs). We collected 40 colorectal carcinomas and 12 non-tumor colorectal tissue specimens from patients with colorectal cancer, as well as 45 tumor and 13 non-tumor specimens from patients with GIST. Expression and localization of

Surgery, 2014

Mammalian target of rapamycin (mTOR) forms 2 active complexes in the cell: the rapamycin-sensitiv... more Mammalian target of rapamycin (mTOR) forms 2 active complexes in the cell: the rapamycin-sensitive mTOR-Raptor (mTORC1) and the rapamycin-insensitive mTOR-Rictor (mTORC2). The latter activates AKT kinase, which promotes tumor cell survival and proliferation by multiple downstream targets. Mammalian stress-activated protein kinase interacting protein 1 (SIN1), an essential subunit of the mTORC2 complex, maintains the integrity of the complex and substrate specificity and regulates Akt activation. The role of mTOR-Rictor complex activation in thyroid carcinogenesis remains unknown. Therefore, we investigated expression patterns of Sin1 in the cells lines of thyroid carcinoma and tumors and their association with AKT activation, histologic type, and tumor aggressiveness. Tissue specimens from 42 patients with thyroid cancer, including follicular (5), papillary (18), medullary (16), and poorly differentiated (3) carcinomas were analyzed via immunohistochemistry for SIN1 expression and AKT phosphorylation at Ser473 residue (Ser473-p-AKT). Eight of 18 papillary carcinomas were aggressive histologic variants. In addition, expression of Sin1 and activation of AKT kinase were analyzed in fresh-frozen tissue samples (normal/tumor), primary cell cultures (papillary thyroid carcinoma [PTC]), and an established thyroid cancer cell line (medullary thyroid carcinoma) by Western blotting. With immunohistochemistry, we found that Sin1 was overexpressed in medullary thyroid carcinomas and aggressive variants of papillary thyroid carcinoma compared with conventional papillary and follicular carcinomas (P < .001). Sin1 expression correlated with AKT activation in the entire study group (P = .002). Using Western blot analysis, we found that Sin1 and p-AKT were detected at a greater level in cultured primary cells from aggressive PTC compared with conventional PTC as well as in cell lines of medullary and anaplastic thyroid carcinoma. High expression levels of SIN1 were detected in papillary thyroid carcinomas compared with benign nodules in immunoblots in which we used fresh-frozen patient samples. Two of the Sin1 protein isoforms, p76 and p55, were detected predominantly in PTC samples. Sin1, a critical factor of the mTORC2 complex is overexpressed in clinically aggressive thyroid cancer types and is associated strongly with activation of AKT kinase. Sin1-dependent AKT activation might represent a target for experimental therapy.

Hormones (Athens, Greece)

The extent of thyroidectomy for papillary thyroid microcarcinoma (PTMC) is debatable. This study ... more The extent of thyroidectomy for papillary thyroid microcarcinoma (PTMC) is debatable. This study investigated the rate and predictive factors of bilateral versus unilateral PTMC with the objective of identifying those patients who may benefit from total thyroidectomy. Between January 2001 and December 2008, 2019 patients who underwent total thyroidectomy were examined. A total of 319 patients diagnosed histopathologically as PTMC were included in the study. The predictive value of age at diagnosis, gender, tumor size, multifocality, lymph node metastasis, thyroid capsule invasion and nonincidental diagnosis using univariate and multivariate analyses were retrospectively analyzed. Of the 319 patients with PTMC, 77 (24.1%) presented bilateral disease. In univariate analysis, size of tumor ≥5 mm (p<0.001), multifocality (p<0.001), lymph node metastases (p<0.001), thyroid capsule invasion (p<0.001) and nonincidental diagnosis (p=0.002) were significantly associated with bila...

Pathology & Oncology Research, 2000

Adiponectin has been proposed to be a mediator of obesity-associated malignancies and to have dir... more Adiponectin has been proposed to be a mediator of obesity-associated malignancies and to have direct antineoplastic effects acting via adiponectin receptors AdipoR1 and AdipoR2. We describe herein the expression of AdipoR1 and AdipoR2 in several cancers not previously studied. We used immunohistochemistry to assess expression of adiponectin receptors in archival specimens of renal cell carcinoma (n=64), hepatocellular carcinoma (n=123), melanoma (n=20), cholangiocarcinoma (n=20), transitional cell carcinoma of the bladder (n=24), ovarian epithelial carcinoma (n=63), cervical squamous cell carcinoma (n= 49), and adrenocortical carcinoma (n=48). To compare expression in malignant versus nonmalignant tissues, we also studied AdipoR1 and AdipoR2 expression in pairs of renal cell carcinoma and adjacent healthy kidney tissue specimens by immunohistochemistry. We also studied mRNA expression in 45 specimens of renal cell carcinoma by real-time polymerase chain reaction. Finally, we utilized Western blotting to confirm the presence of adiponectin receptors and subsequently studied cell signaling pathways of adiponectin in the renal cancer cell line 786-O. Cancers associated with obesity were significantly more likely to express AdipoR1 than cancers not associated with obesity.

Pathology, 2003

To investigate the role of multidrug resistance proteins and topoisomerase IIalpha in colon cance... more To investigate the role of multidrug resistance proteins and topoisomerase IIalpha in colon cancer. Tissue sections from 89 Dukes&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; stage B-D colon cancer patients were selected. The expression of multidrug resistance proteins and topoisomerase IIalpha in primary tumour cells was assessed by standard immunohistochemistry. The extent of their expression was measured by image analysis and was correlated with clinicopathological features of the patients. P-glycoprotein was associated with the presence of lymph node metastasis (P=0.005), vessel invasion (P=0.0001) and perineural invasion (P=0.020). P-glycoprotein is probably involved in the processes of local invasion and metastatic dissemination.

Molecular Cancer Therapeutics, 2007

B-Raf is an important mediator of cell proliferation and survival signals transduced via the Ras-... more B-Raf is an important mediator of cell proliferation and survival signals transduced via the Ras-Raf-MEK-ERK cascade. BRAF mutations have been detected in several tumors, including papillary thyroid carcinoma, but the precise role of B-Raf as a therapeutic target for thyroid carcinoma is still under investigation. We analyzed a panel of 93 specimens and 14 thyroid carcinoma cell lines for the presence of BRAF mutations and activation of the mitogen-activated protein/ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway. We also compared the effect of a B-Raf small inhibitory RNA construct and the B-Raf kinase inhibitor AAL881 on both B-Raf wild-type and mutant thyroid carcinoma cell lines. We found a high prevalence of the T1799A (V600E) mutation in papillary and anaplastic carcinoma specimens and cell lines. There was no difference in patient age, B-Raf expression, Ki67 immunostaining, or clinical stage at presentation between wild-type and BRAF(V600E) specimens. Immunodetection of phosphorylated and total forms of MEK and ERK revealed no difference in their phosphorylation between wild-type and BRAF(V600E) patient specimens or cell lines. Furthermore, a small inhibitory RNA construct targeting the expression of both wild-type B-Raf and B-Raf(V600E) induced a comparable reduction of viability in both wild-type and BRAF(V600E) mutant cancer cells. Interestingly, AAL881 inhibited MEK and ERK phosphorylation and induced apoptosis preferentially in BRAF(V600E)-harboring cells than wild-type ones, possibly because of better inhibitory activity against B-Raf(V600E). We conclude that B-Raf is important for the pathophysiology of thyroid carcinomas irrespective of mutational status. Small molecule inhibitors that selectively target B-Raf(V600E) may provide clinical benefit for patients with thyroid cancer.

Modern Pathology, 2006

Fibrillin is an extracellular matrix (ECM) glycoprotein, a main component of microfibrills, sugge... more Fibrillin is an extracellular matrix (ECM) glycoprotein, a main component of microfibrills, suggested to support cell attachment and to impact cell differentiation and migration. The aim of this study was to investigate fibrillin-1 expression in thyroid carcinomas at mRNA and protein level, since ECM proteins are suggested to be of great importance for the metastatic potential of carcinomas. RNA was extracted from 13 thyroid carcinoma cell lines and RT-PCR analysis with gene-specific primers revealed fibrillin-1 mRNA expression in all cell lines, with highest expression in the follicular carcinoma cell line WRO and lowest expression in the two anaplastic cell lines (APO, FRO). Furthermore, we investigated fibrillin-1 expression by immumohistochemistry in a commercially available tissue microarray including 50 thyroid carcinomas as well as in archival tissue from 33 thyroid carcinomas. Fibrillin-1 demonstrated a cytoplasmic location in the neoplastic cells of almost all carcinomas apart from the follicular ones. The most intense staining was observed in papillary carcinomas with some evidence of a slight increased intensity in advanced stages. Our data indicate that fibrillin-1 is strongly expressed by the neoplastic cells of thyroid carcinomas in different degree in the various histologic types and might be implicated in cell-stroma interaction in terms of signaling, attachment and migration.

Metabolism, 2011

Adiponectin has been associated with colorectal cancer (CRC) risk. This study aims to investigate... more Adiponectin has been associated with colorectal cancer (CRC) risk. This study aims to investigate the association of both adiponectin and tissue expression of its receptors with CRC risk as well as clinicopathological characteristics, notably stage and grade. Determination of serum adiponectin and immunohistochemical expression of adiponectin receptors in adenocarcinoma/normal colorectal tissue was performed in samples from 104 newly diagnosed CRC patients and 208 age-and sexmatched controls. Multiple logistic regression odds ratios and 95% confidence intervals for CRC risk were derived, controlling for a series of covariates. Serum adiponectin was negatively associated with CRC risk (odds ratio, 0.72; confidence interval, 0.53-0.99) and also with tumor grade (P = .05). Expression of both adiponectin receptors was stronger in adenocarcinoma vs normal tissue (P = .001). AdipoR1 expression was negatively associated with nodal stage (P = .03); AdipoR2 expression was positively associated with tumor, node, metastasis stage (P = .01). Established positive associations with red meat consumption and diabetes, and negative associations with physical exercise and plant food consumption were confirmed along with a more than 60% higher risk associated with central obesity. Adiponectin levels and tissue expression of hormonal receptors seem to be associated not only with CRC risk but also with components of clinicopathological characteristics; given power limitations, these results should be interpreted with caution. The exact nature of the association and the underlying pathophysiological mechanisms need to be further examined in large prospective studies assessing adiponectin and its receptors as novel targets for exploring CRC growth. A v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m Metabolism w w w . m e t a b o l i s m j o u r n a l . c o m

Journal of Oral Pathology & Medicine, 2010

BACKGROUND: Peripheral giant cell granuloma is a tumor of the jaw characterized by the presence o... more BACKGROUND: Peripheral giant cell granuloma is a tumor of the jaw characterized by the presence of multinucleated giant cells and mononuclear cells within a fibrous stroma. These lesions are considered to be of a reactive nature rather than neoplastic. Although peripheral giant cell granulomas is a well-described clinical entity, little is known on its pathogenesis. The aim of this study was to investigate the receptor activator of NF-jB ligand (RANKL) and osteoprotegerin (OPG) expression and immunolocalization in giant cell granulomas. METHODS: RANKL and OPG protein expression was evaluated in 22 peripheral giant cell granulomas samples, by means of immunohistochemistry. Staining was evaluated semi-quantitatively, according to the extent and intensity of the stain. RESULTS: RANKL was expressed in all cases with a cytoplasmic staining pattern, whereas OPG expression was detected in 21 of the 22 cases examined. Active multinucleated giant cells exhibited intense immunoreactivity for both proteins. CONCLUSION: RANKL and OPG are expressed in peripheral giant cell granulomas of the jaw in a manner supporting the osteoclastic nature of giant cells whereas the possible osteoclastic lineage of stromal monocytes remains ambiguous.

Journal of Clinical Oncology, 2009

To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's ly... more To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's lymphoma (NHL) with serum adiponectin and leptin levels in a nationwide case-control series. In addition, expression of adiponectin receptors in NHL specimens was assessed, and the association between adipokines and childhood NHL survival and prognosis was examined.

Inflammation, 2010

Recent research evidence shows that the receptor activator of nuclear factor-kappa B ligand (RANK... more Recent research evidence shows that the receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG) play an important role in osteoclastogenesis and the inflammatory bone loss during periodontitis. Bone remodeling process is dependent on the balance of these two proteins while a high ratio of RANKL/OPG characterizes the increased osteolytic process and it has been reported in inflammatory diseases including the periodontal disease. The purpose of this study was to determine the OPG and RANKL mRNA levels in periodontal tissues derived from patients with advanced chronic periodontitis after non-surgical periodontal therapy (SRP) and to compare the RANKL/OPG ration with that in healthy persons. Gingival biopsies were obtained from subjects with clinically healthy periodontium (H) (N=11) and patients with advanced chronic periodontitis (CP) (N=14). Total RNA was isolated from the gingival samples and 1 μg RNA was reverse transcribed to cDNA, followed by polymerase chain reaction (PCR) using specific primers for OPG and RANKL. The efficiency of reverse transcription was verified by the amplification of the GAPDH gene. The intensity of RT-PCR products was analyzed by a densitometer and was normalized to the intensity of the band for the housekeeping gene GAPDH. Immunohistochemical evaluation of the RANKL and OPG expression was also performed. The expression of RANKL as well as of OPG was reduced in CP specimens in comparison to that of healthy persons in a statistical significant way. However, the RANKL/OPG ratio showed to be slightly elevated in CP compared to H specimens but this finding was not of statistical significance. The immunohistochemical analysis revealed a non-uniform expression pattern for both proteins. Although further investigation is needed to identify the specific role of RANKL and OPG protein in periodontitis progression, our data after SRP might indicate the possible involvement of these proteins in the activation of pathways, which regulate the repair of the periodontal tissues.

European Journal of Endocrinology, 2006

Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains di... more Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains difficult in several cases. Endoglin (CD105) is a proliferation-associated and hypoxia-inducible protein abundantly expressed in angiogenic endothelial cells. Vascular endothelial growth factor (VEGF) induces angiogenesis and VEGF-R2 is a tyrosine kinase receptor expressed early in development by endothelial cell precursors. We attempted to examine whether immunohistochemical expression of CD105, VEGF and VEGF-R2 may be useful in distinguishing between parathyroid hyperplasia and neoplasia as well as to elucidate, to some extent, the mechanism of neovascularization in proliferative lesions of the parathyroid gland. Design: Tissue specimens were taken from 38 patients with primary hyperparathyroidism (HPT) (17 adenomas and 21 primary hyperplasias) and from 30 patients with secondary HPT. Normal glands served as controls. Methods: In a standard immunohistochemical procedure, monoclonal antibodies to endoglin, VEGF and VEGF-R2 were applied to detect angiogenic endothelial cells. Immunostaining was estimated by image analysis and statistical analysis was subsequently performed. Results: Positive CD105 immunoreaction was significantly increased in parathyroid adenomas by comparison with primary hyperplasias (PZ0.033) and with secondary hyperplasias (PZ0.033). When parathyroid adenomas, primary hyperplasia and secondary hyperplasia specimens were comparatively evaluated, VEGF immunoreaction was much more common in adenomas (PZ0.018). In addition, in samples with secondary hyperplasia, VEGF-R2 immunoreactivity was positively linked with VEGF expression as well as with the apoptotic index of parathyroid cells (PZ0.038 and 0.010 respectively). In secondary hyperplasia specimens, an inverse correlation between cyclin D1 immunoexpression and angiogenic indexes, such as CD105 and VEGF, was noticed (PZ0.007 and 0.0017 respectively). Conclusions: This study shows increased angiogenesis in parathyroid adenomas compared with parathyroid proliferative lesions. In secondarily hyperplastic glands increased angiogenesis and increased apoptosis occur simultaneously; in the latter glands, the overexpression of cyclin D1 does not appear to be the genetic abnormality responsible for increased angiogenesis.

European Journal of Endocrinology, 1999

Endemic non-toxic goiter (NTG) in Greece has been attributed primarily to iodine deficiency. Thir... more Endemic non-toxic goiter (NTG) in Greece has been attributed primarily to iodine deficiency. Thirty years ago about 60% of the prepubertal boys and girls examined in endemic goiter regions presented with NTG and among them thyroid autoimmunity was rarely detected. Although iodine supplementation has corrected this deficiency during the past 30 years, new cases of NTG still appear. To evaluate the prevalence and type of NTG and the effect of iodine supplementation on them in Greece at present, we performed two cross-sectional clinical studies and a retrospective pathology one: (i) thyroid gland volume and urinary iodine excretion (UIE) were assessed in a representative sample of 1213 schoolchildren from previously endemic and non-endemic regions; (ii) serum thyroxine, tri-iodothyronine, TSH, thyroid autoantibodies (AAB) (anti-thyroid peroxidase and anti-thyroglobulin antibodies) and UIE (in 60 patients) were measured in 300 consecutive patients with NTG from Athens and Heraklion; and (iii) we compared the prevalence of autoimmunity among fine needle aspiration smears of benign thyroid pathologies performed by the same pathologist between 1985 and 1986 (975 cases) and between 1994 and 1995 (2702 cases). We found that 12.5% of the schoolchildren examined in regions with a previous history of endemic goiter had NTG, whereas this percentage was only 1.7% in areas without such a history. In Athens (61.6%) and Heraklion (58.5%) a substantial number of NTG patients were AAB positive and biochemically hypothyroid. UIE in Athens did not differ between patients with autoimmune goiter (ATG) and simple goiter. The prevalence of autoimmune stigmata in pathology smears has increased from 5.94% (years 1985-1986) to 13.91% (years 1994-1995) (P < 0.05). We conclude that: (i) the persistence of endemic goiter in regional foci despite iodine deficiency correction suggests a possible role for a naturally occurring goitrogen; (ii) ATG is the predominant form of NTG in Greece nowadays; and (iii) the five-fold decrease in the prevalence of NTG during the past 30 years followed by the increase of ATG may support the relative character of the latter.

European Journal of Endocrinology, 2002

Objective: The family of fibroblast growth factors stimulates proliferation of cells of mesenchym... more Objective: The family of fibroblast growth factors stimulates proliferation of cells of mesenchymal, epithelial and neuroectodermal origin. One of the members of this family, the product of proto-oncogene int-2, fibroblast growth factor-3, has been found to stimulate mitosis of parathyroid cells in culture. Primary and secondary hyperparathyroidism have no clear differences with regard to the histopathological features of the diseased parathyroid glands. Design: This study was undertaken in order to determine whether int-2 protein is immunohistochemically expressed in normal and abnormal parathyroid glands and to investigate whether there is a differential expression of the int-2 gene product between primary and secondary parathyroid disease. Methods: A sheep anti-human int-2 antibody was applied to tissue sections from 37 samples of primary parathyroid disease (12 sporadic adenomas, 25 hyperplastic glands), from 30 samples of renal hyperparathyroidism, and from seven normal controls. Int-2 immunostaining was evaluated semi-quantitatively. Results: None of the normal parathyroid glands stained positively. Int-2 immunopositive expression was more frequently detected in specimens of uraemic patients than in those of patients with primary parathyroid growth processes ðP ¼ 0:029Þ. The reason for this differential expression appears to be the higher proportion of oxyphilic cells growing in hyperplastic glands of patients with secondary hyperparathyroidism; the latter cells were specifically found to be int-2 immunoreactive. Conclusion: The int-2 gene product is likely to participate in the proliferation of this parathyroid cell subpopulation.

European Journal of Endocrinology, 2003

Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains di... more Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains difficult. Changes in cell cycle control may lead to clonal proliferation and precede tumorigenesis. The parathyroid adenoma 1 oncogene, subsequently identified as the gene encoding cyclin D1, has been shown to be important to parathyroid tumour development. In addition to cell proliferation, the mechanisms of parathyroid cell turnover include apoptosis. The tumour-suppressor activity of the fragile histidine triad gene (FHIT) is linked to its proapoptotic function and cell cycle control. We attempted to evaluate the cellular proliferative kinetics and apoptotic function of the parathyroid glands in patients with non-familial hyperparathyroidism (HPT). Design: Tissue specimens were taken from 40 patients with primary HPT (17 adenomas, two carcinomas and 21 primary hyperplasias) and from 30 patients with secondary HPT. Normal glands served as controls. Methods: In a standard immunohistochemical procedure, monoclonal antibodies to Ki-67 antigen and single-stranded DNA were applied to detect cycling and apoptotic cells respectively; polyclonal antibodies to cyclin D1 and Fhit protein were used. Immunostaining was estimated by image analysis and statistical analysis was subsequently performed. Results: Significantly higher proliferative and apoptotic indexes were detected in the diseased glands in comparison with normal controls. In neoplastic and secondarily hyperplastic glands, apoptotic indexes were higher than in primarily hyperplastic glands; the difference between neoplastic and primarily hyperplastic glands was statistically significant ðP ¼ 0:034Þ: Cyclin D1 was overexpressed in a considerable proportion of tumours (68.4%). A reduction of Fhit protein immunoreactivity was selectively noticed in carcinomas. Conclusions: In primary hyperplasia, the remarkable proliferation of parathyroid glands may be due to the reduction of the apoptotic process. FHIT gene abnormalities are worthy of investigation in parathyroid carcinogenesis.

Endocrine Related Cancer, 2008

Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin r... more Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin receptor expression has not been examined in normal gastrointestinal tissue, colorectal malignancies, or gastrointestinal stromal tumors (GISTs). We collected 40 colorectal carcinomas and 12 non-tumor colorectal tissue specimens from patients with colorectal cancer, as well as 45 tumor and 13 non-tumor specimens from patients with GIST. Expression and localization of adiponectin receptors (AdipoR1 and AdipoR2) were assessed using immunohistochemistry. We also confirmed expression of adiponectin receptors using rtPCR in matched normal and colorectal cancer specimens obtained from five patients. Finally, we detected adiponectin receptors and assessed adiponectin signaling in three colon cancer cell lines. Adiponectin receptor expression, assessed by either rtPCR or immunohistochemistry, was present in normal tissue and was significantly lower than in colorectal carcinomas. Among carcinomas, 95% displayed positive or strongly positive expression of AdipoR1 and 88% of AdipoR2, versus 8% and 0%, respectively, for non-tumor specimens (P!0.0001). AdipoR1 expression assessed by rtPCR was 1.6-fold higher in tumor than in non-tumor tissue (P!0.05). In addition, we found that adiponectin at physiological concentrations can activate in vitro intracellular signaling pathways in three colon cancer cell lines,

Endocrine Pathology, 2010

PI3K/Akt signaling pathway plays critical role in many cell processes. There is indication that e... more PI3K/Akt signaling pathway plays critical role in many cell processes. There is indication that enhanced activation of PI3K/Akt cascade is implicated in thyroid tumors. Aim of this study was to evaluate the mutational status and expression of PI3K/Akt pathway mediators in papillary thyroid carcinoma in Greece. We evaluated the presence of mutations in PIK3CA (exons 9 and 20), AKT1 (exons 6-11), AKT2 (exons 6-11), AKT3 (exons 5-10), PTEN (exons 3-8), and PDPK1 (exons 4-10) genes in 83 papillary thyroid carcinomas by DNA sequencing. The expression levels of phospho-Akt and insulin-like growth factor I receptor (IGF-IR) were evaluated by immunohistochemistry. PIK3CA mutations were found in three samples. The analysis of AKT1 revealed one silent mutation in exon 9 (G726A) in 16 samples. One specimen carried an AKT3 mutation. One missense mutation was found in one sample in PTEN. No mutations were found in AKT2 and PDPK1. Increased levels of phosphorylated total Akt and IGF-IR were identified in some papillary cancers. Our findings indicate that PI3K/Akt signaling pathway is activated in some papillary tumors. However, mutations in genes coding most mediators of the pathway have not been proven to be the major modus of enhanced activation. These data suggest a potential role for PI3K/Akt-mediated signaling in papillary thyroid tumors.

Journal of Clinical Oncology, 2009

To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's ly... more To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's lymphoma (NHL) with serum adiponectin and leptin levels in a nationwide case-control series. In addition, expression of adiponectin receptors in NHL specimens was assessed, and the association between adipokines and childhood NHL survival and prognosis was examined.

Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin r... more Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin receptor expression has not been examined in normal gastrointestinal tissue, colorectal malignancies, or gastrointestinal stromal tumors (GISTs). We collected 40 colorectal carcinomas and 12 non-tumor colorectal tissue specimens from patients with colorectal cancer, as well as 45 tumor and 13 non-tumor specimens from patients with GIST. Expression and localization of

Surgery, 2014

Mammalian target of rapamycin (mTOR) forms 2 active complexes in the cell: the rapamycin-sensitiv... more Mammalian target of rapamycin (mTOR) forms 2 active complexes in the cell: the rapamycin-sensitive mTOR-Raptor (mTORC1) and the rapamycin-insensitive mTOR-Rictor (mTORC2). The latter activates AKT kinase, which promotes tumor cell survival and proliferation by multiple downstream targets. Mammalian stress-activated protein kinase interacting protein 1 (SIN1), an essential subunit of the mTORC2 complex, maintains the integrity of the complex and substrate specificity and regulates Akt activation. The role of mTOR-Rictor complex activation in thyroid carcinogenesis remains unknown. Therefore, we investigated expression patterns of Sin1 in the cells lines of thyroid carcinoma and tumors and their association with AKT activation, histologic type, and tumor aggressiveness. Tissue specimens from 42 patients with thyroid cancer, including follicular (5), papillary (18), medullary (16), and poorly differentiated (3) carcinomas were analyzed via immunohistochemistry for SIN1 expression and AKT phosphorylation at Ser473 residue (Ser473-p-AKT). Eight of 18 papillary carcinomas were aggressive histologic variants. In addition, expression of Sin1 and activation of AKT kinase were analyzed in fresh-frozen tissue samples (normal/tumor), primary cell cultures (papillary thyroid carcinoma [PTC]), and an established thyroid cancer cell line (medullary thyroid carcinoma) by Western blotting. With immunohistochemistry, we found that Sin1 was overexpressed in medullary thyroid carcinomas and aggressive variants of papillary thyroid carcinoma compared with conventional papillary and follicular carcinomas (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001). Sin1 expression correlated with AKT activation in the entire study group (P = .002). Using Western blot analysis, we found that Sin1 and p-AKT were detected at a greater level in cultured primary cells from aggressive PTC compared with conventional PTC as well as in cell lines of medullary and anaplastic thyroid carcinoma. High expression levels of SIN1 were detected in papillary thyroid carcinomas compared with benign nodules in immunoblots in which we used fresh-frozen patient samples. Two of the Sin1 protein isoforms, p76 and p55, were detected predominantly in PTC samples. Sin1, a critical factor of the mTORC2 complex is overexpressed in clinically aggressive thyroid cancer types and is associated strongly with activation of AKT kinase. Sin1-dependent AKT activation might represent a target for experimental therapy.

Hormones (Athens, Greece)

The extent of thyroidectomy for papillary thyroid microcarcinoma (PTMC) is debatable. This study ... more The extent of thyroidectomy for papillary thyroid microcarcinoma (PTMC) is debatable. This study investigated the rate and predictive factors of bilateral versus unilateral PTMC with the objective of identifying those patients who may benefit from total thyroidectomy. Between January 2001 and December 2008, 2019 patients who underwent total thyroidectomy were examined. A total of 319 patients diagnosed histopathologically as PTMC were included in the study. The predictive value of age at diagnosis, gender, tumor size, multifocality, lymph node metastasis, thyroid capsule invasion and nonincidental diagnosis using univariate and multivariate analyses were retrospectively analyzed. Of the 319 patients with PTMC, 77 (24.1%) presented bilateral disease. In univariate analysis, size of tumor ≥5 mm (p<0.001), multifocality (p<0.001), lymph node metastases (p<0.001), thyroid capsule invasion (p<0.001) and nonincidental diagnosis (p=0.002) were significantly associated with bila...

Pathology & Oncology Research, 2000

Adiponectin has been proposed to be a mediator of obesity-associated malignancies and to have dir... more Adiponectin has been proposed to be a mediator of obesity-associated malignancies and to have direct antineoplastic effects acting via adiponectin receptors AdipoR1 and AdipoR2. We describe herein the expression of AdipoR1 and AdipoR2 in several cancers not previously studied. We used immunohistochemistry to assess expression of adiponectin receptors in archival specimens of renal cell carcinoma (n=64), hepatocellular carcinoma (n=123), melanoma (n=20), cholangiocarcinoma (n=20), transitional cell carcinoma of the bladder (n=24), ovarian epithelial carcinoma (n=63), cervical squamous cell carcinoma (n= 49), and adrenocortical carcinoma (n=48). To compare expression in malignant versus nonmalignant tissues, we also studied AdipoR1 and AdipoR2 expression in pairs of renal cell carcinoma and adjacent healthy kidney tissue specimens by immunohistochemistry. We also studied mRNA expression in 45 specimens of renal cell carcinoma by real-time polymerase chain reaction. Finally, we utilized Western blotting to confirm the presence of adiponectin receptors and subsequently studied cell signaling pathways of adiponectin in the renal cancer cell line 786-O. Cancers associated with obesity were significantly more likely to express AdipoR1 than cancers not associated with obesity.

Pathology, 2003

To investigate the role of multidrug resistance proteins and topoisomerase IIalpha in colon cance... more To investigate the role of multidrug resistance proteins and topoisomerase IIalpha in colon cancer. Tissue sections from 89 Dukes&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; stage B-D colon cancer patients were selected. The expression of multidrug resistance proteins and topoisomerase IIalpha in primary tumour cells was assessed by standard immunohistochemistry. The extent of their expression was measured by image analysis and was correlated with clinicopathological features of the patients. P-glycoprotein was associated with the presence of lymph node metastasis (P=0.005), vessel invasion (P=0.0001) and perineural invasion (P=0.020). P-glycoprotein is probably involved in the processes of local invasion and metastatic dissemination.

Molecular Cancer Therapeutics, 2007

B-Raf is an important mediator of cell proliferation and survival signals transduced via the Ras-... more B-Raf is an important mediator of cell proliferation and survival signals transduced via the Ras-Raf-MEK-ERK cascade. BRAF mutations have been detected in several tumors, including papillary thyroid carcinoma, but the precise role of B-Raf as a therapeutic target for thyroid carcinoma is still under investigation. We analyzed a panel of 93 specimens and 14 thyroid carcinoma cell lines for the presence of BRAF mutations and activation of the mitogen-activated protein/ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway. We also compared the effect of a B-Raf small inhibitory RNA construct and the B-Raf kinase inhibitor AAL881 on both B-Raf wild-type and mutant thyroid carcinoma cell lines. We found a high prevalence of the T1799A (V600E) mutation in papillary and anaplastic carcinoma specimens and cell lines. There was no difference in patient age, B-Raf expression, Ki67 immunostaining, or clinical stage at presentation between wild-type and BRAF(V600E) specimens. Immunodetection of phosphorylated and total forms of MEK and ERK revealed no difference in their phosphorylation between wild-type and BRAF(V600E) patient specimens or cell lines. Furthermore, a small inhibitory RNA construct targeting the expression of both wild-type B-Raf and B-Raf(V600E) induced a comparable reduction of viability in both wild-type and BRAF(V600E) mutant cancer cells. Interestingly, AAL881 inhibited MEK and ERK phosphorylation and induced apoptosis preferentially in BRAF(V600E)-harboring cells than wild-type ones, possibly because of better inhibitory activity against B-Raf(V600E). We conclude that B-Raf is important for the pathophysiology of thyroid carcinomas irrespective of mutational status. Small molecule inhibitors that selectively target B-Raf(V600E) may provide clinical benefit for patients with thyroid cancer.

Modern Pathology, 2006

Fibrillin is an extracellular matrix (ECM) glycoprotein, a main component of microfibrills, sugge... more Fibrillin is an extracellular matrix (ECM) glycoprotein, a main component of microfibrills, suggested to support cell attachment and to impact cell differentiation and migration. The aim of this study was to investigate fibrillin-1 expression in thyroid carcinomas at mRNA and protein level, since ECM proteins are suggested to be of great importance for the metastatic potential of carcinomas. RNA was extracted from 13 thyroid carcinoma cell lines and RT-PCR analysis with gene-specific primers revealed fibrillin-1 mRNA expression in all cell lines, with highest expression in the follicular carcinoma cell line WRO and lowest expression in the two anaplastic cell lines (APO, FRO). Furthermore, we investigated fibrillin-1 expression by immumohistochemistry in a commercially available tissue microarray including 50 thyroid carcinomas as well as in archival tissue from 33 thyroid carcinomas. Fibrillin-1 demonstrated a cytoplasmic location in the neoplastic cells of almost all carcinomas apart from the follicular ones. The most intense staining was observed in papillary carcinomas with some evidence of a slight increased intensity in advanced stages. Our data indicate that fibrillin-1 is strongly expressed by the neoplastic cells of thyroid carcinomas in different degree in the various histologic types and might be implicated in cell-stroma interaction in terms of signaling, attachment and migration.

Metabolism, 2011

Adiponectin has been associated with colorectal cancer (CRC) risk. This study aims to investigate... more Adiponectin has been associated with colorectal cancer (CRC) risk. This study aims to investigate the association of both adiponectin and tissue expression of its receptors with CRC risk as well as clinicopathological characteristics, notably stage and grade. Determination of serum adiponectin and immunohistochemical expression of adiponectin receptors in adenocarcinoma/normal colorectal tissue was performed in samples from 104 newly diagnosed CRC patients and 208 age-and sexmatched controls. Multiple logistic regression odds ratios and 95% confidence intervals for CRC risk were derived, controlling for a series of covariates. Serum adiponectin was negatively associated with CRC risk (odds ratio, 0.72; confidence interval, 0.53-0.99) and also with tumor grade (P = .05). Expression of both adiponectin receptors was stronger in adenocarcinoma vs normal tissue (P = .001). AdipoR1 expression was negatively associated with nodal stage (P = .03); AdipoR2 expression was positively associated with tumor, node, metastasis stage (P = .01). Established positive associations with red meat consumption and diabetes, and negative associations with physical exercise and plant food consumption were confirmed along with a more than 60% higher risk associated with central obesity. Adiponectin levels and tissue expression of hormonal receptors seem to be associated not only with CRC risk but also with components of clinicopathological characteristics; given power limitations, these results should be interpreted with caution. The exact nature of the association and the underlying pathophysiological mechanisms need to be further examined in large prospective studies assessing adiponectin and its receptors as novel targets for exploring CRC growth. A v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m Metabolism w w w . m e t a b o l i s m j o u r n a l . c o m

Journal of Oral Pathology & Medicine, 2010

BACKGROUND: Peripheral giant cell granuloma is a tumor of the jaw characterized by the presence o... more BACKGROUND: Peripheral giant cell granuloma is a tumor of the jaw characterized by the presence of multinucleated giant cells and mononuclear cells within a fibrous stroma. These lesions are considered to be of a reactive nature rather than neoplastic. Although peripheral giant cell granulomas is a well-described clinical entity, little is known on its pathogenesis. The aim of this study was to investigate the receptor activator of NF-jB ligand (RANKL) and osteoprotegerin (OPG) expression and immunolocalization in giant cell granulomas. METHODS: RANKL and OPG protein expression was evaluated in 22 peripheral giant cell granulomas samples, by means of immunohistochemistry. Staining was evaluated semi-quantitatively, according to the extent and intensity of the stain. RESULTS: RANKL was expressed in all cases with a cytoplasmic staining pattern, whereas OPG expression was detected in 21 of the 22 cases examined. Active multinucleated giant cells exhibited intense immunoreactivity for both proteins. CONCLUSION: RANKL and OPG are expressed in peripheral giant cell granulomas of the jaw in a manner supporting the osteoclastic nature of giant cells whereas the possible osteoclastic lineage of stromal monocytes remains ambiguous.

Journal of Clinical Oncology, 2009

To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's ly... more To our knowledge, this is the first study exploring the association of childhood non-Hodgkin's lymphoma (NHL) with serum adiponectin and leptin levels in a nationwide case-control series. In addition, expression of adiponectin receptors in NHL specimens was assessed, and the association between adipokines and childhood NHL survival and prognosis was examined.

Inflammation, 2010

Recent research evidence shows that the receptor activator of nuclear factor-kappa B ligand (RANK... more Recent research evidence shows that the receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG) play an important role in osteoclastogenesis and the inflammatory bone loss during periodontitis. Bone remodeling process is dependent on the balance of these two proteins while a high ratio of RANKL/OPG characterizes the increased osteolytic process and it has been reported in inflammatory diseases including the periodontal disease. The purpose of this study was to determine the OPG and RANKL mRNA levels in periodontal tissues derived from patients with advanced chronic periodontitis after non-surgical periodontal therapy (SRP) and to compare the RANKL/OPG ration with that in healthy persons. Gingival biopsies were obtained from subjects with clinically healthy periodontium (H) (N=11) and patients with advanced chronic periodontitis (CP) (N=14). Total RNA was isolated from the gingival samples and 1 μg RNA was reverse transcribed to cDNA, followed by polymerase chain reaction (PCR) using specific primers for OPG and RANKL. The efficiency of reverse transcription was verified by the amplification of the GAPDH gene. The intensity of RT-PCR products was analyzed by a densitometer and was normalized to the intensity of the band for the housekeeping gene GAPDH. Immunohistochemical evaluation of the RANKL and OPG expression was also performed. The expression of RANKL as well as of OPG was reduced in CP specimens in comparison to that of healthy persons in a statistical significant way. However, the RANKL/OPG ratio showed to be slightly elevated in CP compared to H specimens but this finding was not of statistical significance. The immunohistochemical analysis revealed a non-uniform expression pattern for both proteins. Although further investigation is needed to identify the specific role of RANKL and OPG protein in periodontitis progression, our data after SRP might indicate the possible involvement of these proteins in the activation of pathways, which regulate the repair of the periodontal tissues.

European Journal of Endocrinology, 2006

Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains di... more Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains difficult in several cases. Endoglin (CD105) is a proliferation-associated and hypoxia-inducible protein abundantly expressed in angiogenic endothelial cells. Vascular endothelial growth factor (VEGF) induces angiogenesis and VEGF-R2 is a tyrosine kinase receptor expressed early in development by endothelial cell precursors. We attempted to examine whether immunohistochemical expression of CD105, VEGF and VEGF-R2 may be useful in distinguishing between parathyroid hyperplasia and neoplasia as well as to elucidate, to some extent, the mechanism of neovascularization in proliferative lesions of the parathyroid gland. Design: Tissue specimens were taken from 38 patients with primary hyperparathyroidism (HPT) (17 adenomas and 21 primary hyperplasias) and from 30 patients with secondary HPT. Normal glands served as controls. Methods: In a standard immunohistochemical procedure, monoclonal antibodies to endoglin, VEGF and VEGF-R2 were applied to detect angiogenic endothelial cells. Immunostaining was estimated by image analysis and statistical analysis was subsequently performed. Results: Positive CD105 immunoreaction was significantly increased in parathyroid adenomas by comparison with primary hyperplasias (PZ0.033) and with secondary hyperplasias (PZ0.033). When parathyroid adenomas, primary hyperplasia and secondary hyperplasia specimens were comparatively evaluated, VEGF immunoreaction was much more common in adenomas (PZ0.018). In addition, in samples with secondary hyperplasia, VEGF-R2 immunoreactivity was positively linked with VEGF expression as well as with the apoptotic index of parathyroid cells (PZ0.038 and 0.010 respectively). In secondary hyperplasia specimens, an inverse correlation between cyclin D1 immunoexpression and angiogenic indexes, such as CD105 and VEGF, was noticed (PZ0.007 and 0.0017 respectively). Conclusions: This study shows increased angiogenesis in parathyroid adenomas compared with parathyroid proliferative lesions. In secondarily hyperplastic glands increased angiogenesis and increased apoptosis occur simultaneously; in the latter glands, the overexpression of cyclin D1 does not appear to be the genetic abnormality responsible for increased angiogenesis.

European Journal of Endocrinology, 1999

Endemic non-toxic goiter (NTG) in Greece has been attributed primarily to iodine deficiency. Thir... more Endemic non-toxic goiter (NTG) in Greece has been attributed primarily to iodine deficiency. Thirty years ago about 60% of the prepubertal boys and girls examined in endemic goiter regions presented with NTG and among them thyroid autoimmunity was rarely detected. Although iodine supplementation has corrected this deficiency during the past 30 years, new cases of NTG still appear. To evaluate the prevalence and type of NTG and the effect of iodine supplementation on them in Greece at present, we performed two cross-sectional clinical studies and a retrospective pathology one: (i) thyroid gland volume and urinary iodine excretion (UIE) were assessed in a representative sample of 1213 schoolchildren from previously endemic and non-endemic regions; (ii) serum thyroxine, tri-iodothyronine, TSH, thyroid autoantibodies (AAB) (anti-thyroid peroxidase and anti-thyroglobulin antibodies) and UIE (in 60 patients) were measured in 300 consecutive patients with NTG from Athens and Heraklion; and (iii) we compared the prevalence of autoimmunity among fine needle aspiration smears of benign thyroid pathologies performed by the same pathologist between 1985 and 1986 (975 cases) and between 1994 and 1995 (2702 cases). We found that 12.5% of the schoolchildren examined in regions with a previous history of endemic goiter had NTG, whereas this percentage was only 1.7% in areas without such a history. In Athens (61.6%) and Heraklion (58.5%) a substantial number of NTG patients were AAB positive and biochemically hypothyroid. UIE in Athens did not differ between patients with autoimmune goiter (ATG) and simple goiter. The prevalence of autoimmune stigmata in pathology smears has increased from 5.94% (years 1985-1986) to 13.91% (years 1994-1995) (P < 0.05). We conclude that: (i) the persistence of endemic goiter in regional foci despite iodine deficiency correction suggests a possible role for a naturally occurring goitrogen; (ii) ATG is the predominant form of NTG in Greece nowadays; and (iii) the five-fold decrease in the prevalence of NTG during the past 30 years followed by the increase of ATG may support the relative character of the latter.

European Journal of Endocrinology, 2002

Objective: The family of fibroblast growth factors stimulates proliferation of cells of mesenchym... more Objective: The family of fibroblast growth factors stimulates proliferation of cells of mesenchymal, epithelial and neuroectodermal origin. One of the members of this family, the product of proto-oncogene int-2, fibroblast growth factor-3, has been found to stimulate mitosis of parathyroid cells in culture. Primary and secondary hyperparathyroidism have no clear differences with regard to the histopathological features of the diseased parathyroid glands. Design: This study was undertaken in order to determine whether int-2 protein is immunohistochemically expressed in normal and abnormal parathyroid glands and to investigate whether there is a differential expression of the int-2 gene product between primary and secondary parathyroid disease. Methods: A sheep anti-human int-2 antibody was applied to tissue sections from 37 samples of primary parathyroid disease (12 sporadic adenomas, 25 hyperplastic glands), from 30 samples of renal hyperparathyroidism, and from seven normal controls. Int-2 immunostaining was evaluated semi-quantitatively. Results: None of the normal parathyroid glands stained positively. Int-2 immunopositive expression was more frequently detected in specimens of uraemic patients than in those of patients with primary parathyroid growth processes ðP ¼ 0:029Þ. The reason for this differential expression appears to be the higher proportion of oxyphilic cells growing in hyperplastic glands of patients with secondary hyperparathyroidism; the latter cells were specifically found to be int-2 immunoreactive. Conclusion: The int-2 gene product is likely to participate in the proliferation of this parathyroid cell subpopulation.

European Journal of Endocrinology, 2003

Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains di... more Objective: The pathological distinction between parathyroid neoplasms and hyperplasias remains difficult. Changes in cell cycle control may lead to clonal proliferation and precede tumorigenesis. The parathyroid adenoma 1 oncogene, subsequently identified as the gene encoding cyclin D1, has been shown to be important to parathyroid tumour development. In addition to cell proliferation, the mechanisms of parathyroid cell turnover include apoptosis. The tumour-suppressor activity of the fragile histidine triad gene (FHIT) is linked to its proapoptotic function and cell cycle control. We attempted to evaluate the cellular proliferative kinetics and apoptotic function of the parathyroid glands in patients with non-familial hyperparathyroidism (HPT). Design: Tissue specimens were taken from 40 patients with primary HPT (17 adenomas, two carcinomas and 21 primary hyperplasias) and from 30 patients with secondary HPT. Normal glands served as controls. Methods: In a standard immunohistochemical procedure, monoclonal antibodies to Ki-67 antigen and single-stranded DNA were applied to detect cycling and apoptotic cells respectively; polyclonal antibodies to cyclin D1 and Fhit protein were used. Immunostaining was estimated by image analysis and statistical analysis was subsequently performed. Results: Significantly higher proliferative and apoptotic indexes were detected in the diseased glands in comparison with normal controls. In neoplastic and secondarily hyperplastic glands, apoptotic indexes were higher than in primarily hyperplastic glands; the difference between neoplastic and primarily hyperplastic glands was statistically significant ðP ¼ 0:034Þ: Cyclin D1 was overexpressed in a considerable proportion of tumours (68.4%). A reduction of Fhit protein immunoreactivity was selectively noticed in carcinomas. Conclusions: In primary hyperplasia, the remarkable proliferation of parathyroid glands may be due to the reduction of the apoptotic process. FHIT gene abnormalities are worthy of investigation in parathyroid carcinogenesis.

Endocrine Related Cancer, 2008

Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin r... more Circulating adiponectin is inversely associated with colorectal carcinoma. However, adiponectin receptor expression has not been examined in normal gastrointestinal tissue, colorectal malignancies, or gastrointestinal stromal tumors (GISTs). We collected 40 colorectal carcinomas and 12 non-tumor colorectal tissue specimens from patients with colorectal cancer, as well as 45 tumor and 13 non-tumor specimens from patients with GIST. Expression and localization of adiponectin receptors (AdipoR1 and AdipoR2) were assessed using immunohistochemistry. We also confirmed expression of adiponectin receptors using rtPCR in matched normal and colorectal cancer specimens obtained from five patients. Finally, we detected adiponectin receptors and assessed adiponectin signaling in three colon cancer cell lines. Adiponectin receptor expression, assessed by either rtPCR or immunohistochemistry, was present in normal tissue and was significantly lower than in colorectal carcinomas. Among carcinomas, 95% displayed positive or strongly positive expression of AdipoR1 and 88% of AdipoR2, versus 8% and 0%, respectively, for non-tumor specimens (P!0.0001). AdipoR1 expression assessed by rtPCR was 1.6-fold higher in tumor than in non-tumor tissue (P!0.05). In addition, we found that adiponectin at physiological concentrations can activate in vitro intracellular signaling pathways in three colon cancer cell lines,

Endocrine Pathology, 2010

PI3K/Akt signaling pathway plays critical role in many cell processes. There is indication that e... more PI3K/Akt signaling pathway plays critical role in many cell processes. There is indication that enhanced activation of PI3K/Akt cascade is implicated in thyroid tumors. Aim of this study was to evaluate the mutational status and expression of PI3K/Akt pathway mediators in papillary thyroid carcinoma in Greece. We evaluated the presence of mutations in PIK3CA (exons 9 and 20), AKT1 (exons 6-11), AKT2 (exons 6-11), AKT3 (exons 5-10), PTEN (exons 3-8), and PDPK1 (exons 4-10) genes in 83 papillary thyroid carcinomas by DNA sequencing. The expression levels of phospho-Akt and insulin-like growth factor I receptor (IGF-IR) were evaluated by immunohistochemistry. PIK3CA mutations were found in three samples. The analysis of AKT1 revealed one silent mutation in exon 9 (G726A) in 16 samples. One specimen carried an AKT3 mutation. One missense mutation was found in one sample in PTEN. No mutations were found in AKT2 and PDPK1. Increased levels of phosphorylated total Akt and IGF-IR were identified in some papillary cancers. Our findings indicate that PI3K/Akt signaling pathway is activated in some papillary tumors. However, mutations in genes coding most mediators of the pathway have not been proven to be the major modus of enhanced activation. These data suggest a potential role for PI3K/Akt-mediated signaling in papillary thyroid tumors.