DNA methylation patterns in EBV-positive and EBV-negative Hodgkin lymphomas.

Purpose: Hodgkin lymphoma (HL) is characterized by the presence of Hodgkin and Reed-Sternberg cells. Epstein-Barr virus (EBV) infection is thought to play an important role in the development of HL. Although epigenetic alterations, such as aberrant DNA methylation, are known to contribute to the pathogenesis of various malignancies, little is known about such alterations in HL and their putative relationships with EBV infection.

Investigation of miR9-1, miR9-2 and miR9-3 Methylation in Hodgkin Lymphoma.

Background: miR9 is an important tumor suppressor microRNA regulated by DNA methylation in various types of cancers.

Methods: We analyzed the methylation status of the 3 members of the miR9 family in 58 cases of Hodgkin lymphoma (HL) in comparison to 15 reactive lymph nodes. We also assessed the relationships between miR9 methylation and Epstein-Barr virus (EBV) infection and several clinicopathological parameters.

Assessment and biological significance of JC polyomavirus in colorectal cancer in Tunisia.

Purpose: Several reports have indicated the presence of JC polyomavirus (JCV) in many human tumors, including colorectal cancers (CRCs). The presence of JCV infection in CRC patients has not been investigated in African countries.

Methods: We examined the prevalence and the biological significance of JCV in Tunisian CRC patients.

Increased DNA methyltransferase 1 protein expression correlates significantly with intestinal histological type and gender in gastric carcinomas.

Purpose: Promoter hypermethylation and reduced expression of many genes have been found in gastric cancer. DNA methyltransferases are enzymes potentially affecting promoter hypermethylation.

Material And Methods: We analyzed proteins expression of DNA methyltransferase 1 and 3b by immunohistochemistry in 47 surgically resected gastric cancer samples for which clinicopathological characteristics, patient's outcome and methylation status of 11 selected tumor-related genes have been determined.

Methylation of miR124a-1, miR124a-2, and miR124a-3 in Hodgkin lymphoma.

Deregulation of the microRNA miR124a by DNA methylation has been implicated in various malignancies, but no study reported its methylation status in Hodgkin lymphoma (HL). We evaluated the methylation of the three loci encoding for miR124a using methylation-specific PCR in 64 HL patients and 15 reactive lymph nodes obtained from patients with nonmalignant diseases. Results were correlated with clinicopathological parameters.

Correlation between DNA methyltransferases expression and Epstein-Barr virus, JC polyomavirus and Helicobacter pylori infections in gastric carcinomas.

It' is accepted that aberrant expression of DNA methyltransferases (DNMTs) is responsible for hypermethylation in genes. However, there are limited data related to factors inducing aberrant expression of DNMTs. A total of 43 surgically resected gastrc carcinomas (GC) samples were analysed.

Clinicopathologic characteristics of colorectal cancer with microsatellite instability.

Colorectal cancer (CRC) can be classified according to the level of microsatellite instability (MSI) exhibited by the tumor. The aim of this study was to determine MSI status in CRC from Tunisia and to identify clinical and pathological characteristics of MSI-H tumors. Microsatellite status was determined by polymerase chain reaction amplification using standard markers (BAT25, BAT26, D2S123, D5S346 and D17S250, the Bethesda panel) in 44 CRC cases.

Patterns of aberrant DNA hypermethylation in nasopharyngeal carcinoma in Tunisian patients.

Background: Aberrant methylation in the promoter of tumor-related genes is associated closely with epigenetically mediated gene silencing. The aim of the present study was to evaluate the methylation profile of Tunisian nasopharyngeal carcinoma (NPC) and to determine the clinicopathological features of tumors showing this epigenetic alteration.

Methods: Thirty-six archival NPC biopsies were investigated in comparison with 19 non-tumor nasopharyngeal tissue specimens.

Investigation of human papillomavirus in bladder cancer in a series of Tunisian patients.

The association between human papillomavirus (HPV) infection and development of bladder cancer is variable. Furthermore, the prevalence of HPV DNA in bladder carcinoma subtypes varies from study to study. To clarify the impact of HPV infection on the development of bladder carcinoma, we performed a retrospective study on Tunisian patients to determine the status of HPV infection in urothelial carcinoma, squamous cell carcinoma, and adenocarcinoma.

The presence of JC virus in gastric carcinomas correlates with patient's age, intestinal histological type and aberrant methylation of tumor suppressor genes.

JC virus (JCV) is a neurotropic polyomavirus and the causative agent of progressive multifocal leukoencephalopathy. A role for JCV in gastrointestinal malignancies has been recently suggested. This study was carried out to determine the prevalence of polyomaviruses including JCV, BKV and SV40 in gastric cancers in Tunisia and to determine the clinicopathological characteristics of virus-associated gastric carcinomas.

Prevalence and characteristics of Epstein-Barr virus-associated gastric carcinomas in Tunisia.

Objective: Epstein-Barr virus (EBV) has been linked to gastric carcinoma (GC) with worldwide geographical variations of prevalence ranging from 1 to 18% of cases. Investigations carried out in north Africa have shown that some EBV-associated types of cancers are common in this area. This study was taken to determine the prevalence of EBV-associated GC in Tunisia.

Biological significance of promoter hypermethylation of tumor-related genes in patients with gastric carcinoma.

Background: DNA promoter hypermethylation is a potential means of inactivating tumor-related genes in several types of cancers.

Methods: We investigated aberrant promoter hypermethylation of eleven tumor-related genes in 68 gastric carcinomas and 53 adjacent non-tumor tissues using methylation-specific PCR, and we correlated the findings with clinico-pathological features.

Results: In gastric carcinoma tissues, hypermethylation frequencies of the investigated genes were 61.