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

Background: Association between human papillomavirus (HPV) infection and the 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 for the status of HPV infection in urothelial carcinoma, squamous cell carcinoma and adenocarcinoma. Methods: A total of 125 formalin-fixed, paraffin-embedded archival tissue of bladder carcinoma were reviewed and classified according to the World Health Organization (WHO) classification of tumors (119 urothelial carcinomas, five squamous carcinomas and one adenocarcinoma). Anogenital HPV DNA detection was performed with three different polymerase chain reaction (PCR) techniques. The first one, using primers pU-2R/pU-1M specific to high-risk oncogenic HPV. The second one, using primers PU-2R/PU-31B specific to low-risk oncogenic HPV and the third one, employing consensus primers (E1-547R/E1-350L). Results: No evidence of HPV infection was detected by morphological examination and PCR in any case of bladder carcinoma. Conclusion: Our study shows that anogenital HPV investigated are not associated with the pathogenesis of bladder cancer in Tunisia, however, the possibility that other subtypes of HPV contribute to bladder carcinogenesis remains to be clarified

Investigation of human JC and BK polyomaviruses in breast carcinomas

We have previously showed the presence of the simian virus 40 (SV40) and the mouse mammary tumor virus (MMTV)-like in a significant proportions of Tunisian breast carcinomas. However, to date there are no published studies concerning evaluation of the possible implication of the human polyomaviruses JC (JCV) and BK (BKV) in breast carcinomas. The presence of JCV and BKV DNA was investigated by PCR in a 123 primary breast carcinomas and matched adjacent non-tumor breast tissues. The results were correlated to clinicopathological and virological parameters. JCV T-antigen DNA was detected in 23% of breast carcinoma cases; however, all cases were negative for BKV. JCV T antigen PCR products were further confirmed as authentic JCV genome by direct sequencing. JCV was found in invasive ductal carcinomas (28/112 cases) but not in invasive lobular carcinomas (0/5) or medullary carcinomas (0/6). JCV DNA presence correlates inversely with the expression of estrogen (P = 0.022) and progesterone (P = 0.008) receptors. JCV DNA presence correlates also with "triple negative" phenotype (P = 0.021). With regard to virological data, a trend toward an inverse correlation was noted between the presence of JCV and SV40 (P = 0.06). Moreover, significant correlation was found between multiple viral infection (JCV, and/or SV40, and/or MMTV-like in the same tumor) and "triple negative" phenotype (P = 0.001) and also with p53 accumulation (P = 0.028). To the best of our knowledge, this is the first study demonstrating the presence of JCV in a subset of breast carcinomas. Also our results suggest that "triple negative" breast carcinomas are viral-related tumors

Contribution of epigenetic alteration of BRCA1 and BRCA2 genes in breast carcinomas in Tunisian patients

Objective: The aim of this study was to evaluate the contribution of the BRCA1 and BRCA2 promoter methylation in the pathogenesis of sporadic breast cancer in Tunisian patients. Methods: Breast carcinoma tissues (n=117) and available paired normal breast tissues (n=65) from Tunisian women who had no family history were investigated for the methylation status of BRCA1 and BRCA2 promoters using methylation-specific PCR. Breast specimens from women without carcinoma (16 fibroadenomas and 5 mastopathies) were used as control. Results: Hypermethylation of BRCA1 and BRCA2 promoters was detected respectively in 60.7% and 69.2% of the carcinoma tissues, and in only 7.7% and 4.6% of the paired normal breast tissues. None of the fibroadenomas and mastopathies showed hypermethylation. Correlations were found between BRCA1 and BRCA2 hypermethylation and decrease in their mRNA expression (p=0.02 and p=0.009, respectively). Moreover, BRCA1 methylation correlates with patients age (p=0.01) and triple negative (ER-, PR-, HER2-) tumors (p=0.01). Patients with methylated BRCA1 and/or BRCA2 had a significant prolonged survivals compared to those with unmethylated tumors (p=0.002). Conclusion: Our results suggest an important role of BRCA1 and BRCA2 promoter methylation in breast cancer development in the Tunisian population

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. Methods Ninety-six nonselected GC cases (male/female ratio 1.7/1, mean age 60.9 years, range: 20–88 years) were evaluated for the presence of EBV by polymerase chain reaction as well as by in-situ hybridization for EBVencoded small RNAs (EBERs) and immunohistochemistry for LMP-1 and EBNA-2 expression. Results EBV was detected by polymerase chain reaction in 36% of cases, whereas EBERs were detected in the tumor cells in only four cases (4.1%). Immunohistochemistry for LMP-1 and EBNA-2 was negative in all cases. The mean age for patients harboring EBERs-positive GC was 55.7 years (range: 52–59 years). All EBERs-positive GC cases were males of advanced clinical stage (pT3–pT4). According to Lauren’s classification, two cases were of diffuse histological type and two cases were of intestinal type. In three cases, the tumors have a proximal location and in the remaining case the tumor arises in the antrum. All EBV strains detected from EBV-associated GC were exclusively of type A and D, prototype F, and XhoI-maintained variant. Conclusion We conclude that the prevalence of EBV-associated GC in Tunisia is low (4.1%), suggesting that this virus is not an important etiological factor in GC arising in north African populations. The clinicopathological profile of EBV-associated GC in Tunisia did not differ markedly from that found elsewhere

Clinicopathologic significance of DNA methyltransferase 1, 3a, and 3b overexpression in Tunisian breast cancers.

DNA methyltransferase 1, 3a, and 3b affect DNA methylation, and it is thought that they play an important role in the malignant transformation of various cancers. The current study was designed to analyze DNA methyltransferase expression by immunohistochemistry in a series of 94 Tunisian sporadic breast carcinomas. Results were correlated to clinicopathologic parameters and promoter methylation status of 8 tumor suppressor genes (BRCA1, BRCA2, RASSFA1, TIMP3, CDH1, P16, RARβ2, and DAPK). Overexpression of DNA methyltransferase 1, 3a, and 3b was detected in 46.8%, 32%, and 44.7% of cases, respectively. A significant correlation was found between DNA methyltransferase 1 overexpression and Scarff-Bloom-Richardson histologic grade III (P = .01). DNA methyltransferase 3a overexpression was significantly associated with menopausal status (P = .01), Scarff-Bloom-Richardson histologic grade III (P = .0001), estrogen (P = .04) and progesterone (P = .007) receptor negativity, and HER2 overexpression (P = .004). However, DNA methyltransferase 3a overexpression was found less frequently in the luminal A intrinsic breast cancer subtype (9.7%) than in luminal B (53%), HER2 (41%), and triple-negative (50%) subtypes (P = .001). DNA methyltransferase 3b overexpression shows significant correlation with promoter hypermethylation of BRCA1 (P = .03) and RASSFA1 (P = .04) and with the hypermethylator phenotype (more than 4 methylated genes, P = .01). These data suggest that overexpression of various DNA methyltransferases might represent a critical event responsible for the epigenetic inactivation of multiple tumor suppressor genes, leading to the development of aggressive forms of sporadic breast cancer