Lobna Ayadi

Hypermethylation of RARβ2 correlates with high COX-2 expression and poor prognosis in patients with colorectal carcinoma

Silencing of gene expression by aberrant methylation at the CpG islands is common in human tumors, including colorectal cancer. This epigenetic alteration affects promoter of genes having crucial cellular functions such as tumor suppressor, DNA repair, apoptosis, cell adhesion, etc. We investigated the methylation status in the promoter regions of the RARβ2, RASSF1A, DAPKinase, and CDH1 genes in 73 colorectal carcinoma and 43 paired normal tissues of Tunisian patients using methylation-specific PCR assays. The association between methylation status and the clinicopathological features was evaluated. To determine whether aberrant methylation affects gene expression, we performed immunohistochemistry analysis for E-cadherin and COX-2, a target gene of RARβ2. The methylation frequencies vary from 80.8% for RARβ2 to 35.6% for RASSF1A while in non-tumor-paired samples; the frequencies of methylation are significantly lower for all the fourth genes tested. The methylation status did not correlate with any of the clinical features considered; however, aberrant methylation of RARβ2 was associated with a shortened overall patients’ survival (p logranku2009=u20090.026); nevertheless, it needs to be confirmed on larger sample size. Moreover, a significant inverse association was observed between methylation status of RARβ2 and COX-2 protein expression in tumor specimen (pu2009=u20090.014). On the other hand, we found that loss of E-cadherin expression was significantly associated with aberrant methylation of the CDH1 promoter (pu2009=u20090.005). Our findings showed that RARβ2 was frequently methylated in colorectal cancer and correlated with a worse prognosis and high expression of COX-2 suggesting a link between these two proteins in colorectal carcinogenesis. We also showed that epigenetic alteration of CDH1 is a major mechanism of the loss of E-cadherin protein expression in primary colorectal tumors.

Expression of COX-2 and E-cadherin in Tunisian patients with colorectal adenocarcinoma.

Cyclo-oxygenase 2 (COX-2) and E-cadherin are promising biomarkers for cancer diagnosis and therapy. The aim of this study was to examine the expression of these two proteins in primary colorectal adenocarcinomas and to investigate their association with clinicopathological characteristics including survival of patients. Immunostaining of E-cadherin and COX-2 was assessed in 70 primary colorectal adenocarcinomas from Tunisian patients. Membranous E-cadherin immunostaining and cytoplasmic COX-2 expression were observed in 74.3% and 68.6% of cases respectively. A significant association was found between COX-2 expression and age at diagnosis (P=0.02), and vessel invasion (P=0.037). The expression of E-cadherin correlated with age at diagnosis (P=0.01), and tumor size (P=0.02). In addition, by multivariate analysis, we revealed a significant association with 1-year disease free survival and a tendency with distant metastasis (P=0.017 and P=0.065 respectively). On the other hand, tumors exhibiting COX-2+/E-cadherin-profile were larger (P=0.006), and in an advanced stage (P=0.001). Survival analysis showed that COX-2 over-expression confers a reduced overall survival rate (Plog rank=0.036) and is an independent factor predictive for prognosis.

Aberrant methylation of hMLH1 and p16INK4a in Tunisian patients with sporadic colorectal adenocarcinoma

The methylation of CpG islands in the promoters is associated with loss of protein via repression of gene transcription. Several studies have demonstrated that tumour suppressor and DNA repair genes are often aberrantly hypermethylated in colorectal cancer. The present study was conducted to examine whether the methylation profile of p16INK4a and hMLH1 (human mutL homologue 1) promoters was associated with clinical features and patients survival in CRC (colorectal carcinoma). Aberrant methylation of p16INK4a and hMLH1 promoters was found in 47.2 and 53.4% of tumours respectively. For adjacent non-tumoral mucosa, p16INK4a was fully unmethylated in 30% of the cases, whereas hMLH1 was predominantly unmethylated (76%). Methylation of p16INK4a correlated with gender and tumour size (P=0.005 and 0.035 respectively), whereas those of hMLH1 significantly correlated with overall survival (P log rank=0.007). Concomitant methylation of p16INK4a and hMLH1 was associated with TNM (tumour, lymph node and metastases) stage and tumour size (P=0.024 and 0.021 respectively). Our data show that loss of hMLH1 expression through aberrant methylation could be used as a marker of poor prognosis in CRC.

Gliosarcoma with osteosarcomatous features: a short illustrated review

IntroductionGliosarcoma is a rare, malignant, biphasic brain tumor formed by both glioblastoma and sarcomatous components. Various lines of differentiation are described in the latter component, but most commonly fibrosarcomatous and pleomophic sarcoma are present. Osteosarcomatous features are exceedingly rare.ObjectiveWe report a case of gliosarcoma with osteosarcomatous features in a 33-year-old woman.MethodsHistologically, the sarcomatous portion displayed a typical pattern of fibrosarcoma associated with areas of osteoid formation.Results and conclusionImmunohistochemical glial fibrillary acid protein (GFAP) expression was seen only in the glioblastoma portion. Clinicopathological characteristics and radiological data of this rare condition were reviewed. Possible differential diagnoses and potential histogenesis were also discussed.

Expression and Mutation Pattern of β-Catenin and Adenomatous Polyposis Coli in Colorectal Cancer Patients

BACKGROUND AND AIMSnβ-Catenin and adenomatous polyposis coli (APC) are major components of the Wnt pathway. This study aimed to investigate the expression of β-catenin and APC in tumors and lymph nodes in colorectal cancer (CRC) patients and the mutational spectrum of the genes coding these proteins.nnnMETHODSnExpression of APC and β-catenin was examined in 124 tumors and 41 lymph nodes. Exon 3 of CTNNB1 and the mutation cluster region (MCR) in exon 15 of the APC gene were screened for mutation by PCR-sequencing.nnnRESULTSnNuclear/cytoplasmic immunostaining of β-catenin was detected in 58.1 and 48.8% in tumors and lymph nodes, respectively. In tumors, abnormal expression of β-catenin correlated with tumor size and with those in lymph nodes. Membranous β-catenin expression occurred in 41.9 and 14.6% of tumors and lymph nodes, respectively. In tumors, lack of membranous β-catenin correlated with high invasiveness and metastatic potential. Positive immunostaining for APC was observed in 2 and 14% of tumors and lymph nodes, respectively. Overexpression in nucleus/cytoplasm and lack of membranous β-catenin significantly correlated with a reduced overall survival. Among 25 tumors, four harbour mutation in Ser33 and Ser47 and overexpress the β-catenin in the nucleus/cytoplasm. Mutations were identified in the APC gene in 13 tumors and six mutations were novel.nnnCONCLUSIONSnPositive association between aberrant expression of β-catenin in the nucleus/cytoplasm of tumors and lymph nodes was observed. Nucleus/cytoplasmic accumulation of β-catenin and loss of membranous expression are related to reduced survival and could serve as a candidate prognostic predictor.

Expression of p16INK4a, alone or combined with p53, is predictive of better prognosis in colorectal adenocarcinoma in Tunisian patients.

IntroductionAlterations in different signaling pathways are involved in initiation and progression of colorectal carcinoma, such as those related to p53, MLH1, p16INK4a, Kras, etc. AimThis study was conducted with the aim to investigate the expression of p16INK4a and p53 in colorectal cancer (CRC) and evaluated their correlation with major clinicopathologic features and patients’ survival. Materials and MethodsThe expression of p16INK4a and p53 were analyzed by immunohistochemistry on 70 paraffin specimens of CRC. ResultsPositive immunostaining for p16INK4a and p53 was observed in 27 (38.6%) and 53 (80%) cases, respectively. Significant correlation between loss of p16INK4a expression and tumor size was found (P=0.008), whereas overexpression of p16INK4a correlated with favorable prognosis parameters, such as absence of lymph node metastasis (P=0.029) and early stage of CRC (P=0.027). Furthermore, p53 overexpression significantly correlated with distal tumor location (P=0.022) and was related to a better overall survival in the group of patients with distal colon carcinomas (P=0.002). Patients with p16INK4a-positive tumors had a significant longer overall survival time than patients with p16INK4a-negative carcinomas (P=0.033). In addition, Cox regression model showed that overexpression of p16INK4a is an independent factor for prognosis with depth of invasion, p53 accumulation, and coincident abnormal expression of p16INK4a or p53. ConclusionOur data suggest that the assessment of both p53 and p16INK4a expression might be helpful in predicting prognosis in patients with colorectal cancer.

Pediatric Angiosarcoma of Soft Tissue: A Rare Clinicopathologic Entity

Angiosarcomas are rare tumors that predominantly affect adults and elderly patients. Although angiosarcomas are well described in a variety of clinical settings, they have been poorly studied in children and little is known about their biology, natural history, or optimal treatment. Childhood angiosarcomas are exceedingly rare. The head and neck region and mediastinum seem to be the preferred locations. Most tumors are high-grade tumors. Vasoformative architecture is not always obvious on light microscopy requiring the benefit of immunohistochemical study. The differential diagnosis includes Kaposi sarcoma, epithelioid hemangioendothelioma, hemangiopericytoma, and spindle cell hemangioendothelioma whose prognosis is different. Complete resection is required for patients with localized tumors. Malignant vascular tumors are rare in children in the first 2 decades of life and when they do occur they seem to be more aggressive than in adults. Pathologic diagnosis is difficult particularly in poorly differentiated angiosarcomas requiring immunohistochemical study to confirm vascular differentiation.

High prevalence of the c.1227_1228dup (p.Glu410GlyfsX43) mutation in Tunisian families affected with MUTYH-associated-polyposis

Germline mutations in the base excision repair gene MUTYH have been associated with recessive inheritance of multiple colorectal adenomas. Screening of the MUTYH gene was carried on index cases of 10 unrelated Tunisian families and on available DNA samples from some members. Three germline mutations: c.536Axa0>xa0G (p.Y179C), c.1187 Gxa0>xa0A (p.G396D) and c.1227_1228dup (p.Glu410GlyfsX43), were identified in the homozygous or compound heterozygous state in 8 out of 10 families. The c.1227_1228dup (p.Glu410GlyfsX43) mutation was the most frequent, since it was found in biallelic homozygous in 7 probands and 2 members of family F1 and in compound heterozygous associated with the c.536 Axa0>xa0G (p.Y179C) or c.1187 Gxa0>xa0A (p.G396D) in family F2. Haplotype analysis revealed that the 8 families are unrelated. Moreover, in sporadic colorectal cancer, the c.1227_1228dup (p.Glu410GlyfsX43) mutation was identified in 13xa0% of patients compared to the p.G396D and p.Y179C found in 1.2 and 2.12xa0% respectively. Our data shows the high prevalence of the p.Glu410GlyfsX43 mutation in Tunisian families affected with MUTYH associated polyposis as well as in sporadic colorectal carcinoma.

Alport syndrome and diffuse leiomyomatosis

Review on Alport syndrome and diffuse leiomyomatosis, with data on clinics, and the genes involved.

Overexpression of miR-10b in colorectal cancer patients: Correlation with TWIST-1 and E-cadherin expression

MicroRNAs are emergent players of epigenetics that function as oncogenes or tumor suppressors and that have been implicated in regulating diverse cellular pathways. MiR-10b is an oncogenic microRNA involved in tumor invasion and metastasis in various cancers. Our data have shown that miR-10b is overexpressed in colorectal cancer samples in comparison with non-tumorous adjacent mucosa (pu2009=u20090.0025) and that it is associated with severe features such as tumor size >5u2009cm (pu2009=u20090.023), distant metastasis (pu2009=u20090.0022), non-differentiated tumors (pu2009=u20090.016), and vascular invasion (pu2009=u20090.01). Regarding the regulation of its expression, positive correlation between the loss of miR-10b and aberrant DNA methylation (pu2009=u20090.02) as well as a loss of TWIST-1 messenger RNA (pu2009=u20090.018) have been observed. Furthermore, expression analysis of the downstream miR-10b targets has shown that there are associations between low HOXD10 messenger RNA and E-cadherin protein levels (pu2009<u20090.0001, pu2009=u20090.0008, respectively) and overexpression of miR-10b. Our data suggests that overexpression of miR-10b results from high levels of TWIST-1 and may induce a decrease of E-cadherin membranous protein levels, thus contributing to the acquisition of metastatic phenotypes in colorectal cancer.