Mark Jabbour - Academia.edu (original) (raw)

Papers by Mark Jabbour

Theor Biol Med Model, 2009

Background: Midsegment duplication (dup) of chromatid arms may be symmetric or asymmetric. It can... more Background: Midsegment duplication (dup) of chromatid arms may be symmetric or asymmetric. It can be argued that every dup should yield a discommensured RC with (a) loss of at least one duplicated unit to the template counterpart and; (b) deletion of all sections of the replicating chromatid arm that are distal to both the gap left by the duplicating process and the segment closest to the centromere.

Theoretical Biology and Medical Modelling, 2009

International journal of surgical pathology, Jan 21, 2016

Despite the increase in the incidence of thyroid carcinomas, the occurrence of collision tumors i... more Despite the increase in the incidence of thyroid carcinomas, the occurrence of collision tumors in the thyroid remains a rare event. We present the case of a 69-year-old female who presented to the emergency department with a chief complaint of painful neck swelling. Imaging revealed a large right hemithyroid mass and a left hemithyroid nodule. Fine needle aspiration of the lesions and subsequent total thyroidectomy revealed a Hürthle cell carcinoma in the right lobe and bilateral multicentric papillary carcinoma foci, including 2 foci with a classical pattern and 1 encapsulated follicular variant in the isthmus. BRAF gene mutation analysis revealed V600E gene mutation in the classical variants of papillary carcinoma and in the Hürthle cell carcinoma. The focus of follicular variant of papillary carcinoma in the isthmus and a sample from normal thyroid tissue did not harbor BRAF mutations. This case is remarkable in being an unusual report of a follicular Hürthle cell carcinoma harb...

International journal of surgical pathology, 2016

Vascular transformation of lymph node sinuses represents a rare benign entity mimicking malignant... more Vascular transformation of lymph node sinuses represents a rare benign entity mimicking malignant counterparts such as nodal Kaposi sarcoma. The presence of mildly atypical benign mesothelial cells within nodal sinuses raises the possibility of metastatic malignancy. Herein, a rare case of vascular transformation of lymph node sinuses with reactive sinusoidal mesothelial cells is outlined as a unique benign pathology and a potential mimicker of a malignant collision tumor.

Frontiers in oncology, 2015

Journal of gastrointestinal oncology, 2015

Leiomyosarcoma arising in the colorectum is a rare malignancy of the smooth muscles accounting fo... more Leiomyosarcoma arising in the colorectum is a rare malignancy of the smooth muscles accounting for less than 1% of gastrointestinal tumors. Surgery remains the most accepted modality for the treatment of this entity however management of liver metastases remains controversial. From 1998 to 2009, five patients diagnosed with primary leiomyosarcoma of colorectal origin with metastatic liver disease, underwent liver resections at the American University of Beirut Medical Center. The median overall survival was 47 months (range, 7-135 months). Leiomyosarcoma of colorectal origin with liver metastasis is a very rare entity. Long-term survival can be achieved after surgical resection and should be considered for all patients.

Frontiers in Oncology, 2015

Breast cancer is the most common cancer in women worldwide. Elucidation of underlying biology and... more Breast cancer is the most common cancer in women worldwide. Elucidation of underlying biology and molecular pathways is necessary for improving therapeutic options and clinical outcomes. CLN3 protein (CLN3p), deficient in neurodegenerative CLN3 disease is anti-apoptotic, and defects in the CLN3 gene cause accelerated apoptosis of neurons in CLN3 disease and up-regulation of ceramide. Dysregulated apoptotic pathways are often implicated in the development of the oncogenic phenotype. Predictably, CLN3 mRNA expression and CLN3 protein were up-regulated in a number of human and murine breast cancer-cell lines. Here, we determine CLN3 expression in non-tumor vs. tumor samples from fresh and formalin-fixed/paraffin-embedded (FFPE) breast tissue and analyze the association between CLN3 overexpression and different clinicopathological characteristics of breast cancer patients. Additionally, gene expression of 28 enzymes involved in sphingolipid metabolism was determined. CLN3 mRNA is overexpressed in tumor vs. non-tumor breast tissue from FFPE and fresh samples, as well as in mouse MCF7 breast cancer compared to MCF10A normal cells. Of the clinicopathological characteristics of tumor grade, age, menopause status, estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2), only absence of HER2 expression correlated with CLN3 overexpression. Sphingolipid genes for ceramide synthases 2 and 6 (CerS2; CerS6), delta(4)-desaturase sphingolipid 2 (DEGS2), and acidic sphingomyelinase (SMPD1) displayed higher expression levels in breast cancer vs. control tissue, whereas ceramide galactosyltransferase (UGT8) was underexpressed in breast cancer samples. CLN3 may be a novel molecular target for cancer drug discovery with the goal of modulation of ceramide pathways.

Molecular and Cellular Biology, 2015

Restoration of p53 has been suggested as a therapeutic approach in tumors. However, the timing of... more Restoration of p53 has been suggested as a therapeutic approach in tumors. However, the timing of p53 restoration in relation to its efficacy during tumor progression is still unclear. We now show that restoration of p53 in murine pre-malignant proliferating pineal lesions resulted in cellular senescence, while p53 restoration in invasive pineal tumors did not. The effectiveness of p53 restoration was not dependent on p19(Arf) expression, but showed inverse correlation with Mdm2 expression. In tumor cells, p53 restoration became effective when paired with either DNA damaging therapy or with Nutlin, an inhibitor of p53-Mdm2 interaction. Interestingly, inactivation of p53 after senescence resulted in re-entry into the cell cycle and rapid tumor progression. Evaluation of a panel of human supratentorial primitive neuroectodermal tumors (sPNET) showed low activity of the p53 pathway. Together, this data suggests that restoration of the p53 pathway has different effects in premalignant versus invasive pineal tumors, and that p53 activation needs to be continually sustained, as reversion from senescence occurs rapidly with aggressive tumor growth when p53 is lost again. Finally, p53 restoration approaches may be worth exploring in sPNET, where the p53 gene is intact but the pathway inactive in the majority of examined tumors.

Acta gastro-enterologica Belgica

Arteriovenous malformations are common causes of lower gastrointestinal bleeding in the elderly. ... more Arteriovenous malformations are common causes of lower gastrointestinal bleeding in the elderly. Among them, angiodysplasia is one subtype that appears on endoscopy as red, flat superficial lesions, and sometimes slightly elevated. Colonic angiodysplasia is very rarely seen as a polypoid lesion. The present case describes a bleeding large polypoid colonic angiodysplasia in a 60-year-old man. It was removed endoscopically using a PolyLoop ligature device without complications.

PLOS ONE, 2015

Triple negative breast cancer lacks estrogen, progesterone and epidermal growth factor receptors ... more Triple negative breast cancer lacks estrogen, progesterone and epidermal growth factor receptors rendering it refractory to available targetedtherapies. TNBC is associated with central fibrosis and necrosis, both indicators of tumor hypoxia. Hypoxia inducible factor 1α is up-regulated under hypoxia and its expression is associated with induction of angiogenesis resulting in proliferation, aggressive tumor phenotype and metastasis. In this study we evaluate the potential use of HIF-1α as aTNBC-specific marker. 62 TNBC, 64 HER2+, and 64 hormone-receptors positive breast cancer cases were evaluated for central fibrosis and necrosis, HIF-1α, HIF-1β, VEGFR3, CD31 expression and microvessel density. RNA extraction from paraffin-embedded samples, followed by quantitative real-time polymerase chain reaction (qRT-PCR) evaluation of HIF-1α and VEGF transcripts was performed on 54 cases (18 from each subtype). HIF-1α protein was expressed in 35.5% TNBC, 45.3% HER2+and 25.0% ER+/PR+ (p = 0.055; χ2 test). PCRanalysis of subgroup of breast cancers, 84.2% expressed HIF-1α protein and its transcripts, while only 66.7% expressed VEGF transcripts simultaneously with the HIF-1α protein and its transcripts. Central fibrosis and necrosis was highest in TNBC (p = 0.015; χ2 test), while MVD was comparable among all groups (p = 0.928; χ2 test). VEGFR3 was highest in TNBC expressing HIF-1α. HIF-1β protein was expressed in 32.0% of HIF-1α(+), and in (44.3%) of HIF-1α(-) breast cancer cases (p = 0.033; χ2 test). Moreover, HIF-1α expression in cases with central fibrosis and necrosis was highest in the HER2+ followed by the TNBC (p = 0.156; χ2 test). A proportion of TNBC express HIF-1α but not in a significantly different manner from other breast cancer subtypes. The potential of anti-HIF-1α targeted therapy is therefore not a candidate for exclusive use in TNBC, but should be considered in all breast cancers, especially in the setting of clinically aggressive or refractory disease.

Journal of Oral and Maxillofacial Pathology, 2015

Cervical ganglioneuromas are extremely rare with approximately six case reports. The current repo... more Cervical ganglioneuromas are extremely rare with approximately six case reports. The current report highlights a unique collision tumor between a cervical ganglioneuroma and a metastatic undifferentiated carcinoma arising from a primary gingival mass. A 53-year-old male presented with a 2 cm left gingival mass that was excised and treated with systemic chemotherapy. Consequently, 9 months later, he developed a 3.2 cm left submandibular mass followed by recurrence of the left gingival mass. From the clinicopathologic perspective, this had to be separated from the differentials: ganglioneuroblastoma or metastatic involvement of a lymph node from primary gingival undifferentiated carcinoma.

Blood cancer journal, 2014

Primary effusion lymphoma (PEL) is a rare aggressive subset of non-Hodgkin B-cell lymphoma. It is... more Primary effusion lymphoma (PEL) is a rare aggressive subset of non-Hodgkin B-cell lymphoma. It is caused by Kaposi sarcoma-associated herpesvirus/human herpesvirus type 8 (KSHV/HHV8). It occurs mainly, but not exclusively, in HIV-positive patients. PEL predominantly develops in serous cavities and occasionally in extracavitary regions. PEL carries a very poor prognosis with a median survival time of <6 months. Indeed, currently used treatment modalities such as CHOP chemotherapy are far from achieving complete and sustainable remission. Therefore, there is no clear standard of care established in the treatment of PEL patients, stressing the need for novel-targeted approaches. Here, we have attempted a comprehensive assessment of the treatment of PEL, discussed avant-garde therapies and updated the state of preclinical research with promising clinical applications in the field. These include inhibitors of viral replication, modulators of cell signaling and inflammation, nuclear fa...

Medical hypotheses, 2006

The origin of spontaneous human brain tumors has been recently debated as originating from a stem... more The origin of spontaneous human brain tumors has been recently debated as originating from a stem rather than a progenitor cell. Based on the statistical distribution of a selected group of primary brain tumors, and on the clonality and field theory for cancer growth, we propose as plausible the contribution of progenitor cells in the origin of the most common brain tumors such as, pediatric, mixed (glial and neuronal), and the aggressive glioblastoma multiforme in adults. Operationally, stem cell is defined as having a renewal probability of p=1, a progenitor 0<p<1, and a terminally differentiated cell as p=0. The space-time field location (microenvironment, cell-cell interactions...) and mitotic potential of a cell limits the distinguishability between stem and progenitors, due to the interconvertibility of these states via the process of retrodifferentiation (dedifferentiation). If excessively iterated retrodifferentiation of a mitotically competent cell prompts such a cell...

International Journal of Cancer, 2015