Burkhard Helmke - Academia.edu (original) (raw)

Papers by Burkhard Helmke

International Journal of Cancer, 2012

Recurrent chromosomal alterations are found in roughly 20% of all uterine fibroids but in the maj... more Recurrent chromosomal alterations are found in roughly 20% of all uterine fibroids but in the majority cytogenetic changes are lacking. Recently, mutations of the gene mediator subcomplex 12 (MED12) have been detected in a majority of fibroids but no information is available whether or not they co-occur with cytogenetic subtypes as, e.g., rearrangements of the genes encoding high mobility group AT-hook (HMGA) proteins. In a total of 80 cytogenetically characterized fibroids from 50 patients, we were not only able to confirm the frequent occurrence of MED12 mutations but also to stratify two mutually exclusive pathways of leiomyomagenesis with either rearrangements of HMGA2 reflected by clonal chromosome abnormalities affecting 12q14~15 or by mutations affecting exon 2 of MED12. On average the latter mutations were associated with a significantly smaller tumor size. However, G>A transitions of nucleotides c.130 or c.131 correlate with a significantly larger size of the fibroids compared to other MED12 mutations thus explaining the high prevalence of the former mutations among clinically detectable fibroids. Interestingly, fibroids with MED12 mutations expressed significantly higher levels of the gene encoding wingless-type MMTV integration site family, member 4 (WNT4). Based on these findings and data from the literature, we hypothesize that estrogen and the mutated MED12 cooperate in activating the Wnt pathway which in turn activates β-catenin known to cause leiomyoma-like lesions in a mouse model. The occurrence of a "fibroid-type mutation" in a rare histologic subtype of endometrial polyps suggests that this mechanism is not confined to uterine leiomyomas.

Circulation, Oct 28, 2008

Anticancer Research, 2004

Anticancer Research, May 1, 2012

International Journal of Oncology, 2004

As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor f... more As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor for the development of melanoma, we screened this malignancy for UV-specific C right curved arrow T and CC right curved arrow TT DNA mutations as described in squamous and basal cell carcinomas of the skin. Mitochondrial (mt) DNA was addressed which is known to be highly more susceptible for mutations than nuclear DNA. In the mt genome we chose part of the non-coding displacement-loop (D-loop) containing two hypermutable (C)n tracts especially prone for C right curved arrow T and CC right curved arrow TT changes. A total of 69 melanoma resection specimens was investigated by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) electrophoresis, followed by DNA cloning and sequencing. We detected alterations of the mt D-loop fragment in 4/34 (12%) melanoma primary tumours and in 7/35 (20%) cutaneous and subcutaneous metastases which was no statistically higher proportion upon Fisher's exact test (p=0.17). Among these 11 positive cases, 9 exhibited alterations in the (C)n microsatellite sequences indicating microsatellite instability (MSI) of mtDNA (C)n tracts. Besides 7 insertions and 2 deletions of nucleotides, 11 mutations occurred including only 4 UV-specific C right curved arrow T mutations in a nodular melanoma of the skin and in two subcutaneous metastases. CC right curved arrow TT mutations were not detected in any tissue sample. As (C)n tract alterations occurred in 2/9 primary melanomas with subsequent metastasis, whereas all 20 non-metastasizing cutaneous melanomas were not affected, these somatic changes may reflect genomic imbalance during tumour progression and may be useful for the assessment of patients' prognosis.

Oncology Reports

Celiac disease (CD) is an inflammatory disorder associated with an increased risk of small bowel ... more Celiac disease (CD) is an inflammatory disorder associated with an increased risk of small bowel adenocarcinoma. Recent studies have demonstrated aberrant CpG island methylation (CIM) in chronic inflammation, aging and cancer. We hypothesized that CIM may link CD to small bowel carcinogenesis. We determined microsatellite instability (MSI), CIM, and expression of MLH1 and MGMT in 3 CD-associated small bowel carcinomas and corresponding non-neoplastic mucosa. The results were compared to those of small bowel mucosa from CD patients without carcinoma and 20 small bowel carcinomas from a non-CD origin. A high level CIM/MSI phenotype was found in all of the 3 CD-associated carcinomas and was associated with loss of MLH1 expression due to hypermethylation of the MLH1 promoter. This phenotype was noted in only 2 of the 20 investigated non-CD-associated carcinomas. Low-level CIM was already detectable in 9 of the 12 non-neoplastic mucosa samples of CD patients and in non-CD-associated carc...

The Journal of Pathology: Clinical Research, 2015

Deleted in Malignant Brain Tumors 1 (DMBT1) has been proposed as a candidate tumor suppressor gen... more Deleted in Malignant Brain Tumors 1 (DMBT1) has been proposed as a candidate tumor suppressor gene for brain, lung, and digestive tract cancer. In particular, alterations of the gene and/or a loss of expression have been observed in gastric, colorectal, and esophageal carcinomas. Initial evidence has accumulated that DMBT1 may represent a multifunc- tional protein. Because the consequences of a

Molecular cytogenetics, 2014

Recent findings on genetic changes in uterine leiomyomas suggest these benign tumors being a hete... more Recent findings on genetic changes in uterine leiomyomas suggest these benign tumors being a heterogeneous group of diseases in terms of molecular pathogenesis with those showing karyotype alterations as well as those characterized only by cytogenetically invisible mutations of mediator subcomplex 12 (MED12). Herein, five uterine leiomyomas (UL) with an apparently normal karyotype that lacked MED12-mutations were investigated by copy number variation arrays along with their matching myometrium to search for small genomic imbalances. Of five tumors one showed chromothripsis-like phenomena with numerous gains and losses of small segments mainly clustered to five chromosomal regions i.e. 2p14-2pter, 2q33.1-2q37.3, 5q31.3-5qter,11q14.1-11qter, and 18p11.21-18q2.3. Apparently, these cells had escaped detection by classical cytogenetics. Histologically, the tumor presented as a cellular leiomyoma with extended hyalinization. Of the remaining four tumors, one had a small intragenic deletio...

International journal of gynecological pathology : official journal of the International Society of Gynecological Pathologists, 2014

Uterine fibroids rank among the most frequent symptomatic human tumors at all. Recent data sugges... more Uterine fibroids rank among the most frequent symptomatic human tumors at all. Recent data suggest that mutations of the mediator subcomplex 12 gene (MED12) and rearrangements of the gene-encoding high-mobility group protein AT-hook 2 (HMGA2) characterize major genetic subtypes of these tumors, which, for example, differ by their average size. Herein, we have investigated a total of 289 fibroids from 120 patients. Of these fibroids, 256 were fully genetically analyzed. Of the latter group, 20 (7.8%) fibroids had a chromosomal rearrangement of 12q14-15 reflecting a rearranged allele of HMGA2 and 179 (69.9%) fibroids had a mutation of MED12. The remaining tumors had either another genetic abnormality or no detectable abnormality at all. We were able to demonstrate that tumors of both groups also display striking differences of their frequency in individual patients. Whereas 70.0% (14/20) HMGA2-mutated fibroids made their appearance as solitary nodules, 85.5% (153/179) MED12-mutated fi...

PloS one, 2014

In pleomorphic adenomas of the salivary glands (PASG) recurrent chromosomal rearrangements affect... more In pleomorphic adenomas of the salivary glands (PASG) recurrent chromosomal rearrangements affecting either 8q12 or 12q14∼15 lead to an overexpression of the genes of the genuine transcription factor PLAG1 or the architectural transcription factor HMGA2, respectively. Both genes are also affected by recurrent chromosomal rearrangements in benign adipocytic tumors as e. g. lipomas and lipoblastomas. Herein, we observed a strong correlation between the expression of HMGA2 and PLAG1 in 14 benign and 23 malignant thyroid tumors. To address the question if PLAG1 can be activated by HMGA2, the expression of both genes was quantified in 32 uterine leiomyomas 17 of which exhibited an overexpression of HMGA2. All leiomyomas with HMGA2 overexpression also revealed an activation of PLAG1 in the absence of detectable chromosome 8 abnormalities affecting the PLAG1 locus. To further investigate if the overexpression of PLAG1 is inducible by HMGA2 alone, HMGA2 was transiently overexpressed in MCF-...

Anticancer research, 2012

The expression of high mobility group protein AT-hook2 (HMGA2) indicates a worse prognosis in man... more The expression of high mobility group protein AT-hook2 (HMGA2) indicates a worse prognosis in many epithelial malignancies, such as colon cancer. The present study addresses methodological aspects, as well as the genetic background, of the HMGA2 expression in colon cancer. Samples of 38 colon carcinomas were studied for the expression of HMGA2 by quantitative Real-Time PCR (qRT-PCR). In selected cases, immunohistochemistry (IHC) was also performed. The overexpression of HMGA2, compared to adjacent mucosa, is not consistent among colon carcinomas: Only a minority of carcinomas strongly overexpressed HMGA2, but in no more than 50% of the tumors did the expression exceed the average value in mucosa samples. qRT-PCR clearly reveals a continuum between cases with high and low expression. For HMGA2-based risk assessment, continuous rather than discontinuous models seem to be most appropriate. However, in daily practice, IHC seems to be a suitable method to stratify for high-risk patients.

Amyloid : the international journal of experimental and clinical investigation : the official journal of the International Society of Amyloidosis, 2007

A 63-year-old Caucasian male, diagnosed with dilated cardiomyopathy in 1993, remained clinically ... more A 63-year-old Caucasian male, diagnosed with dilated cardiomyopathy in 1993, remained clinically stable for several years. In 2003, a marked increase of N-terminal pro-natriuretic peptide serum level (611 ng/ml to 4926 ng/ml) was observed; left ventricular (LV) septum thickness was 10 mm. In addition, sensorimotor polyneuropathy and autonomic dysfunction occurred. Further progression of heart failure occurred despite unchanged systolic LV function. Endomyocardial biopsy in 2006 revealed transthyretin amyloidosis by Congo red and immunohistochemical staining, as well as Val94Ala substitution by transthyretin gene analysis. Cardiac amyloid deposition was quantified by technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) scintigraphy. Mutational search of the relatives (n = 1) was unremarkable. The transthyretin Val94Ala mutation is characterized by sensorimotor polyneuropathy, autonomic dysfunction, and gastrointestinal and cardiac involvement with amyloid. This mut...

BMC cancer, 2005

Downstream of Ras, the serine/threonine kinase B-raf has been reported to be mutated, among other... more Downstream of Ras, the serine/threonine kinase B-raf has been reported to be mutated, among other carcinomas, in a substantial subset of primary melanomas with a preponderance of mutations within the kinase domain including the activating V599E and V599K transitions. We here investigated a representative series of 60 resection specimens of cutaneous and subcutaneous melanoma metastases for the presence of mutations within the activation segment (exon 15) of the B-raf kinase domain by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) gel electrophoresis. Sequencing of cloned PCR-SSCP amplicons resulted in 24 (40%) samples harbouring somatic mutations which is not exceeding the mutation frequency in recently investigated primary melanomas. The activating mutation T1796A was present in 24/60 (40%) resection specimens, followed in frequency by the oncogenic g1795A mutation in 8/60 (13%) cases. As to the B-raf protein sequence, the acidic amino acid trans...

International journal of oncology, 2004

Seeking to identify melanoma-associated genes by comparing gene expression in uncultured primary ... more Seeking to identify melanoma-associated genes by comparing gene expression in uncultured primary melanoma specimens with those in nevi, from which melanomas often are known to arise, we applied subtractive suppression hybridization. Generating a subtracted library of candidate genes up-regulated in primary melanomas, this library contained cDNA fragments of the genes encoding heat shock cognate protein (HSP73) and major histocompatibility complex (HLA-DR) which were overexpressed in further 19 independent melanoma resection specimens on cDNA Southern blots when compared to 19 acquired melanocytic nevi. Upon immunohistochemistry, HSP73 protein expression was detected in the cytoplasm of melanoma cells in primary tumours and metastases. In primary melanomas, the proportion of HSP73 protein expressing cells correlated with tumour thickness according to Breslow which was statistically significant. HSP73 immunostaining was stronger in melanoma metastases when compared with acquired melan...

Cancer Investigation, 2009

To evaluate the prevalence and meaning of cutaneous human papillomavirus (HPV) types in HNSCC 51 ... more To evaluate the prevalence and meaning of cutaneous human papillomavirus (HPV) types in HNSCC 51 patients were analyzed for the prevalence of cutaneous as well as mucosal HPV. HPV DNA was demonstrated in 18 (35%) of 51 tumors. The majority of these HPV types belong to so-called cutaneous HPV types, whereas only HPV 6 and HPV 16 were from the mucosal HPV types. A possible role for cutaneous HPV types as co-factors in the oncogenesis of HNSCC remains to be elucidated and may be relevant for future strategies of cancer prevention.

International Journal of Oncology, 2004

As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor f... more As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor for the development of melanoma, we screened this malignancy for UV-specific C right curved arrow T and CC right curved arrow TT DNA mutations as described in squamous and basal cell carcinomas of the skin. Mitochondrial (mt) DNA was addressed which is known to be highly more susceptible for mutations than nuclear DNA. In the mt genome we chose part of the non-coding displacement-loop (D-loop) containing two hypermutable (C)n tracts especially prone for C right curved arrow T and CC right curved arrow TT changes. A total of 69 melanoma resection specimens was investigated by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) electrophoresis, followed by DNA cloning and sequencing. We detected alterations of the mt D-loop fragment in 4/34 (12%) melanoma primary tumours and in 7/35 (20%) cutaneous and subcutaneous metastases which was no statistically higher proportion upon Fisher's exact test (p=0.17). Among these 11 positive cases, 9 exhibited alterations in the (C)n microsatellite sequences indicating microsatellite instability (MSI) of mtDNA (C)n tracts. Besides 7 insertions and 2 deletions of nucleotides, 11 mutations occurred including only 4 UV-specific C right curved arrow T mutations in a nodular melanoma of the skin and in two subcutaneous metastases. CC right curved arrow TT mutations were not detected in any tissue sample. As (C)n tract alterations occurred in 2/9 primary melanomas with subsequent metastasis, whereas all 20 non-metastasizing cutaneous melanomas were not affected, these somatic changes may reflect genomic imbalance during tumour progression and may be useful for the assessment of patients' prognosis.

International Journal of Cancer, 2012

Recurrent chromosomal alterations are found in roughly 20% of all uterine fibroids but in the maj... more Recurrent chromosomal alterations are found in roughly 20% of all uterine fibroids but in the majority cytogenetic changes are lacking. Recently, mutations of the gene mediator subcomplex 12 (MED12) have been detected in a majority of fibroids but no information is available whether or not they co-occur with cytogenetic subtypes as, e.g., rearrangements of the genes encoding high mobility group AT-hook (HMGA) proteins. In a total of 80 cytogenetically characterized fibroids from 50 patients, we were not only able to confirm the frequent occurrence of MED12 mutations but also to stratify two mutually exclusive pathways of leiomyomagenesis with either rearrangements of HMGA2 reflected by clonal chromosome abnormalities affecting 12q14~15 or by mutations affecting exon 2 of MED12. On average the latter mutations were associated with a significantly smaller tumor size. However, G>A transitions of nucleotides c.130 or c.131 correlate with a significantly larger size of the fibroids compared to other MED12 mutations thus explaining the high prevalence of the former mutations among clinically detectable fibroids. Interestingly, fibroids with MED12 mutations expressed significantly higher levels of the gene encoding wingless-type MMTV integration site family, member 4 (WNT4). Based on these findings and data from the literature, we hypothesize that estrogen and the mutated MED12 cooperate in activating the Wnt pathway which in turn activates β-catenin known to cause leiomyoma-like lesions in a mouse model. The occurrence of a "fibroid-type mutation" in a rare histologic subtype of endometrial polyps suggests that this mechanism is not confined to uterine leiomyomas.

Circulation, Oct 28, 2008

Anticancer Research, 2004

Anticancer Research, May 1, 2012

International Journal of Oncology, 2004

As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor f... more As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor for the development of melanoma, we screened this malignancy for UV-specific C right curved arrow T and CC right curved arrow TT DNA mutations as described in squamous and basal cell carcinomas of the skin. Mitochondrial (mt) DNA was addressed which is known to be highly more susceptible for mutations than nuclear DNA. In the mt genome we chose part of the non-coding displacement-loop (D-loop) containing two hypermutable (C)n tracts especially prone for C right curved arrow T and CC right curved arrow TT changes. A total of 69 melanoma resection specimens was investigated by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) electrophoresis, followed by DNA cloning and sequencing. We detected alterations of the mt D-loop fragment in 4/34 (12%) melanoma primary tumours and in 7/35 (20%) cutaneous and subcutaneous metastases which was no statistically higher proportion upon Fisher's exact test (p=0.17). Among these 11 positive cases, 9 exhibited alterations in the (C)n microsatellite sequences indicating microsatellite instability (MSI) of mtDNA (C)n tracts. Besides 7 insertions and 2 deletions of nucleotides, 11 mutations occurred including only 4 UV-specific C right curved arrow T mutations in a nodular melanoma of the skin and in two subcutaneous metastases. CC right curved arrow TT mutations were not detected in any tissue sample. As (C)n tract alterations occurred in 2/9 primary melanomas with subsequent metastasis, whereas all 20 non-metastasizing cutaneous melanomas were not affected, these somatic changes may reflect genomic imbalance during tumour progression and may be useful for the assessment of patients' prognosis.

Oncology Reports

Celiac disease (CD) is an inflammatory disorder associated with an increased risk of small bowel ... more Celiac disease (CD) is an inflammatory disorder associated with an increased risk of small bowel adenocarcinoma. Recent studies have demonstrated aberrant CpG island methylation (CIM) in chronic inflammation, aging and cancer. We hypothesized that CIM may link CD to small bowel carcinogenesis. We determined microsatellite instability (MSI), CIM, and expression of MLH1 and MGMT in 3 CD-associated small bowel carcinomas and corresponding non-neoplastic mucosa. The results were compared to those of small bowel mucosa from CD patients without carcinoma and 20 small bowel carcinomas from a non-CD origin. A high level CIM/MSI phenotype was found in all of the 3 CD-associated carcinomas and was associated with loss of MLH1 expression due to hypermethylation of the MLH1 promoter. This phenotype was noted in only 2 of the 20 investigated non-CD-associated carcinomas. Low-level CIM was already detectable in 9 of the 12 non-neoplastic mucosa samples of CD patients and in non-CD-associated carc...

The Journal of Pathology: Clinical Research, 2015

Deleted in Malignant Brain Tumors 1 (DMBT1) has been proposed as a candidate tumor suppressor gen... more Deleted in Malignant Brain Tumors 1 (DMBT1) has been proposed as a candidate tumor suppressor gene for brain, lung, and digestive tract cancer. In particular, alterations of the gene and/or a loss of expression have been observed in gastric, colorectal, and esophageal carcinomas. Initial evidence has accumulated that DMBT1 may represent a multifunc- tional protein. Because the consequences of a

Molecular cytogenetics, 2014

Recent findings on genetic changes in uterine leiomyomas suggest these benign tumors being a hete... more Recent findings on genetic changes in uterine leiomyomas suggest these benign tumors being a heterogeneous group of diseases in terms of molecular pathogenesis with those showing karyotype alterations as well as those characterized only by cytogenetically invisible mutations of mediator subcomplex 12 (MED12). Herein, five uterine leiomyomas (UL) with an apparently normal karyotype that lacked MED12-mutations were investigated by copy number variation arrays along with their matching myometrium to search for small genomic imbalances. Of five tumors one showed chromothripsis-like phenomena with numerous gains and losses of small segments mainly clustered to five chromosomal regions i.e. 2p14-2pter, 2q33.1-2q37.3, 5q31.3-5qter,11q14.1-11qter, and 18p11.21-18q2.3. Apparently, these cells had escaped detection by classical cytogenetics. Histologically, the tumor presented as a cellular leiomyoma with extended hyalinization. Of the remaining four tumors, one had a small intragenic deletio...

International journal of gynecological pathology : official journal of the International Society of Gynecological Pathologists, 2014

Uterine fibroids rank among the most frequent symptomatic human tumors at all. Recent data sugges... more Uterine fibroids rank among the most frequent symptomatic human tumors at all. Recent data suggest that mutations of the mediator subcomplex 12 gene (MED12) and rearrangements of the gene-encoding high-mobility group protein AT-hook 2 (HMGA2) characterize major genetic subtypes of these tumors, which, for example, differ by their average size. Herein, we have investigated a total of 289 fibroids from 120 patients. Of these fibroids, 256 were fully genetically analyzed. Of the latter group, 20 (7.8%) fibroids had a chromosomal rearrangement of 12q14-15 reflecting a rearranged allele of HMGA2 and 179 (69.9%) fibroids had a mutation of MED12. The remaining tumors had either another genetic abnormality or no detectable abnormality at all. We were able to demonstrate that tumors of both groups also display striking differences of their frequency in individual patients. Whereas 70.0% (14/20) HMGA2-mutated fibroids made their appearance as solitary nodules, 85.5% (153/179) MED12-mutated fi...

PloS one, 2014

In pleomorphic adenomas of the salivary glands (PASG) recurrent chromosomal rearrangements affect... more In pleomorphic adenomas of the salivary glands (PASG) recurrent chromosomal rearrangements affecting either 8q12 or 12q14∼15 lead to an overexpression of the genes of the genuine transcription factor PLAG1 or the architectural transcription factor HMGA2, respectively. Both genes are also affected by recurrent chromosomal rearrangements in benign adipocytic tumors as e. g. lipomas and lipoblastomas. Herein, we observed a strong correlation between the expression of HMGA2 and PLAG1 in 14 benign and 23 malignant thyroid tumors. To address the question if PLAG1 can be activated by HMGA2, the expression of both genes was quantified in 32 uterine leiomyomas 17 of which exhibited an overexpression of HMGA2. All leiomyomas with HMGA2 overexpression also revealed an activation of PLAG1 in the absence of detectable chromosome 8 abnormalities affecting the PLAG1 locus. To further investigate if the overexpression of PLAG1 is inducible by HMGA2 alone, HMGA2 was transiently overexpressed in MCF-...

Anticancer research, 2012

The expression of high mobility group protein AT-hook2 (HMGA2) indicates a worse prognosis in man... more The expression of high mobility group protein AT-hook2 (HMGA2) indicates a worse prognosis in many epithelial malignancies, such as colon cancer. The present study addresses methodological aspects, as well as the genetic background, of the HMGA2 expression in colon cancer. Samples of 38 colon carcinomas were studied for the expression of HMGA2 by quantitative Real-Time PCR (qRT-PCR). In selected cases, immunohistochemistry (IHC) was also performed. The overexpression of HMGA2, compared to adjacent mucosa, is not consistent among colon carcinomas: Only a minority of carcinomas strongly overexpressed HMGA2, but in no more than 50% of the tumors did the expression exceed the average value in mucosa samples. qRT-PCR clearly reveals a continuum between cases with high and low expression. For HMGA2-based risk assessment, continuous rather than discontinuous models seem to be most appropriate. However, in daily practice, IHC seems to be a suitable method to stratify for high-risk patients.

Amyloid : the international journal of experimental and clinical investigation : the official journal of the International Society of Amyloidosis, 2007

A 63-year-old Caucasian male, diagnosed with dilated cardiomyopathy in 1993, remained clinically ... more A 63-year-old Caucasian male, diagnosed with dilated cardiomyopathy in 1993, remained clinically stable for several years. In 2003, a marked increase of N-terminal pro-natriuretic peptide serum level (611 ng/ml to 4926 ng/ml) was observed; left ventricular (LV) septum thickness was 10 mm. In addition, sensorimotor polyneuropathy and autonomic dysfunction occurred. Further progression of heart failure occurred despite unchanged systolic LV function. Endomyocardial biopsy in 2006 revealed transthyretin amyloidosis by Congo red and immunohistochemical staining, as well as Val94Ala substitution by transthyretin gene analysis. Cardiac amyloid deposition was quantified by technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) scintigraphy. Mutational search of the relatives (n = 1) was unremarkable. The transthyretin Val94Ala mutation is characterized by sensorimotor polyneuropathy, autonomic dysfunction, and gastrointestinal and cardiac involvement with amyloid. This mut...

BMC cancer, 2005

Downstream of Ras, the serine/threonine kinase B-raf has been reported to be mutated, among other... more Downstream of Ras, the serine/threonine kinase B-raf has been reported to be mutated, among other carcinomas, in a substantial subset of primary melanomas with a preponderance of mutations within the kinase domain including the activating V599E and V599K transitions. We here investigated a representative series of 60 resection specimens of cutaneous and subcutaneous melanoma metastases for the presence of mutations within the activation segment (exon 15) of the B-raf kinase domain by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) gel electrophoresis. Sequencing of cloned PCR-SSCP amplicons resulted in 24 (40%) samples harbouring somatic mutations which is not exceeding the mutation frequency in recently investigated primary melanomas. The activating mutation T1796A was present in 24/60 (40%) resection specimens, followed in frequency by the oncogenic g1795A mutation in 8/60 (13%) cases. As to the B-raf protein sequence, the acidic amino acid trans...

International journal of oncology, 2004

Seeking to identify melanoma-associated genes by comparing gene expression in uncultured primary ... more Seeking to identify melanoma-associated genes by comparing gene expression in uncultured primary melanoma specimens with those in nevi, from which melanomas often are known to arise, we applied subtractive suppression hybridization. Generating a subtracted library of candidate genes up-regulated in primary melanomas, this library contained cDNA fragments of the genes encoding heat shock cognate protein (HSP73) and major histocompatibility complex (HLA-DR) which were overexpressed in further 19 independent melanoma resection specimens on cDNA Southern blots when compared to 19 acquired melanocytic nevi. Upon immunohistochemistry, HSP73 protein expression was detected in the cytoplasm of melanoma cells in primary tumours and metastases. In primary melanomas, the proportion of HSP73 protein expressing cells correlated with tumour thickness according to Breslow which was statistically significant. HSP73 immunostaining was stronger in melanoma metastases when compared with acquired melan...

Cancer Investigation, 2009

To evaluate the prevalence and meaning of cutaneous human papillomavirus (HPV) types in HNSCC 51 ... more To evaluate the prevalence and meaning of cutaneous human papillomavirus (HPV) types in HNSCC 51 patients were analyzed for the prevalence of cutaneous as well as mucosal HPV. HPV DNA was demonstrated in 18 (35%) of 51 tumors. The majority of these HPV types belong to so-called cutaneous HPV types, whereas only HPV 6 and HPV 16 were from the mucosal HPV types. A possible role for cutaneous HPV types as co-factors in the oncogenesis of HNSCC remains to be elucidated and may be relevant for future strategies of cancer prevention.

International Journal of Oncology, 2004

As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor f... more As epidemiological data suggest ultraviolet (UV) radiation to be the major environmental factor for the development of melanoma, we screened this malignancy for UV-specific C right curved arrow T and CC right curved arrow TT DNA mutations as described in squamous and basal cell carcinomas of the skin. Mitochondrial (mt) DNA was addressed which is known to be highly more susceptible for mutations than nuclear DNA. In the mt genome we chose part of the non-coding displacement-loop (D-loop) containing two hypermutable (C)n tracts especially prone for C right curved arrow T and CC right curved arrow TT changes. A total of 69 melanoma resection specimens was investigated by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) electrophoresis, followed by DNA cloning and sequencing. We detected alterations of the mt D-loop fragment in 4/34 (12%) melanoma primary tumours and in 7/35 (20%) cutaneous and subcutaneous metastases which was no statistically higher proportion upon Fisher's exact test (p=0.17). Among these 11 positive cases, 9 exhibited alterations in the (C)n microsatellite sequences indicating microsatellite instability (MSI) of mtDNA (C)n tracts. Besides 7 insertions and 2 deletions of nucleotides, 11 mutations occurred including only 4 UV-specific C right curved arrow T mutations in a nodular melanoma of the skin and in two subcutaneous metastases. CC right curved arrow TT mutations were not detected in any tissue sample. As (C)n tract alterations occurred in 2/9 primary melanomas with subsequent metastasis, whereas all 20 non-metastasizing cutaneous melanomas were not affected, these somatic changes may reflect genomic imbalance during tumour progression and may be useful for the assessment of patients' prognosis.