Characteristics of epstein barr virus variants associated with gastric carcinoma in Southern Tunisia

<p>Abstract</p> <p>Backgroud</p> <p>EBV-associated Gastric Carcinoma (EBVaGC) has a distinct clinical features and its prevalence is variable worldwide.</p> <p>Results</p> <p>To determine the prevalence of EBVaGC in Tunisia, EBV-encoded small RNA (EBER) expression was assessed in 81 gastric carcinoma (GC) specimens. The nuclear EBER expression was detected in 12 out of 81 GC cases (14.81%) and concordance between the score range of EBER staining and the number of EBV DNA copies as estimate by QPCR is observed. On the other hand, we found that EBVaGC strongly correlated with age at diagnosis, and weakly with tumor differentiation and venous invasion.</p> <p>Furthermore, the EBVaGC specimens were subjected to determine the EBV DNA polymorphisms. Our results show a unique genetic profile of the EBV strains regarding the A and D types, the F prototype, the retention of <it>Xho</it>I restriction site and the 30 bp del-LMP1 variant. <b><it>According to our previous studies on nasopharyngeal carcinoma (NPC), we suggested that EBV strains associated to GC and NPC shared some similarities in Tunisian patients</it>.</b></p> <p>Conclusion</p> <p>The prevalence of EBVaGC is of 14.81% in the southern Tunisia and that common EBV strain are associated with both NPC and GC which are likely to differ from Asian strains. Our findings support therefore a certain geographical distribution of EBV strains which is not restricted to EBV-associated malignancies.</p

Clinical Significance of Epigenetic Inactivation of hMLH1 and BRCA1 in Tunisian Patients with Invasive Breast Carcinoma

Aberrant hypermethylation of gene promoter regions is one of the mechanisms for inactivation of tumour suppressor genes in many human cancers including breast carcinoma. In the current study, we aimed to assess by MSP, the methylation pattern of two cancer-related genes involved in DNA repair: hMLH1 (mutL homolog 1, colon cancer, nonpolyposis type 2 (E. coli) and BRCA1 (breast cancer 1, early onset) in 78 primary breast cancers from Tunisian patients. The methylation frequencies were 24.36% for hMLH1 and 46% for BRCA1. BRCA1 methylation correlated with age at diagnosis (P = .015) and 5-years disease free survival (P = .016) while hMLH1 methylation was more frequent in larger tumors (P = .002) and in presence of distant metastasis (P = .004). Furthermore, methylation of hMLH1 significantly correlated with high level of P53 expression (P = .006) and with overall survival (P = .015) suggesting that silencing of hMLH1 through aberrant promoter methylation could be used as a poor prognosis indicator in breast cancer

Translational control of human p53 expression in yeast mediated by 5′-UTR–ORF structural interaction

We have expressed human p53 cDNA in the yeast Saccharomyces cerevisiae and shown that the level of production and the length of the p53 protein depends on the presence of untranslated mRNA regions (UTRs). The expression of the ORF alone leads to a p53 protein of correct size (53 kDa) that accumulates to high levels, concomitantly with the presence of a small amount of a p40 protein (40 kDa). However, when either the entire 5′-UTR and a part of the 3′- or 5′-UTR alone is used, this leads to the production of small amounts of the 40 kDa truncated form only. The p40 protein corresponds to a truncated form of p53 at the C-terminal extremity since it reacts only with a monoclonal antibody recognising the N-terminal epitope. This effect on the amount and length of p53 protein had no correlation at the mRNA level, suggesting that translational control probably occurs through the 5′-UTR. We propose a model of structural interaction between this UTR and a part of the ORF mRNA for the regulation of p53 expression in this heterologous context

Expression and role of nuclear receptor coregulators in colorectal cancer

International audienceColorectal cancer (CRC) is one of the most common human cancers and the cause of about 700000 deaths per year worldwide. Deregulation of the WNT/β-catenin pathway is a key event in CRC initiation. This pathway interacts with other nuclear signaling pathways, including members of the nuclear receptor superfamily and their transcription coregulators. In this review, we provide an overview of the literature dealing with the main coactivators (NCoA-1 to 3, NCoA-6, PGC1-α, p300, CREBBP and MED1) and corepressors (N-CoR1 and 2, NRIP1 and MTA1) of nuclear receptors and summarize their links with the WNT/β-catenin signaling cascade, their expression in CRC and their role in intestinal physiopathology

Extraction and purification of hepatitis B virus-like M particles from a recombinant Saccharomyces cerevisiae strain using alumina powder.

International audienceA recombinant hepatitis B surface antigen (HBsAg) has been produced in the yeast Saccharomyces cere- visiae and used as a vaccine against hepatitis B virus (HBV) infection. The present study aimed to optimize the extraction of recombinant virus-like particles (rVLPs) to develop a simple purification procedure based on gel filtration and high performance size-exclusion chromatography. The findings showed that disruption of yeast cells with alumina powder increased the yield of the total proteins (290 mg/l) and rVLPs (1 mg/l) compared to the values for glass beads (171 mg/l and 0.5 mg/l), as estimated by quantita- tive ELISA. The purification of rVLPs was performed by two consecutive gel filtration chromatographic steps, namely Sephacryl S-200 followed by SEC-250 HPLC. The purified M protein was analyzed by atomic force microscopy and shown to assemble in particles that were able to recognize HBV antibodies in the sera of patients with chronic hepatitis B, providing evidence for their immunoreactivity

Negative/Low HER2 expression alone or combined with E-cadherin positivity is predictive of better prognosis in patients with breast carcinoma

The loss of E-cadherin expression leads to absence of tissue integrity, an essential step in tumor progression. Methylation of CpG islands in the promoter region of the CDH1 gene coding E-cadherin might be an alternative for gene silencing. In the present study, we investigate the expression of E-cadherin and hormone receptors in invasive ductal breast carcinoma (IDCs). Protein expression was analysed immunohistochemically in 87 cases, including 26 familial tumors. The most interesting results revealed a significantly reduced E-cadherin expression in cases with familial history compared to sporadic tumors (p=0.009), as well as with tumors ≤5cm (p=0.022). Moreover, HER2 over-expression was associated with distant metastasis (p=0.011) and overall survival (p log rank=0.028). Tumors displaying negative/low HER2 expression combined with E-cadherin positivity confer better patient survival (p=0.052). Triple Negative tumors (TN) were more frequently found in patients with advanced grade (GIII) (p=0.001) and TNM (III+IV) (p=0.018) which supports the aggressive behavior of TN tumors. On the other hand, hypermethylation of CDH1 gene promoter was observed in 46% of hereditary cases and strongly associated with loss of E-cadherin expression (p=0.002). Furthermore, patients with unmethylated CDH1 pattern have a better 5-year disease free survival (p=0.021). In conclusion, in patients with hereditary breast cancer, the CpG methylation event contributes to the loss of E-cadherin expression. On the other hand, HER2 over-expression is predictive of worse prognosis, either alone or combined with loss of E-cadherin expression in Tunisian patients with breast cancer

B1.12: a novel peptide interacting with the extracellular loop of the EBV oncoprotein LMP1

Abstract Latent membrane protein 1 (LMP1) encoded by the Epstein-Barr virus (EBV) plays an important role in EBV-induced cell transformation. Down-regulation of the LMP1 expression had shown promising results on cancer cell therapy. In this study, we identified by Phage display a novel peptide called B1.12 (ACPLDLRSPCG) which selectively binds to the extracellular loop (B1) of the LMP1 oncoprotein as demonstrated by molecular docking, NMR and ITC. Using an LMP1 expressing cell line, we showed that B1.12 decreased cell viability, and induced G0/G1 cell cycle arrest. In addition, the expression of A20, pAkt, and pNFkb (pRelA536) in C666-1 cells treated with B1.12 decreased compared to the untreated cells. In conclusion, we selected a novel peptide able to bind specifically to the extracellular loop of LMP1 and thus modulate its oncogenic properties

Identification of a Novel Methylated Gene in Nasopharyngeal Carcinoma: TTC40

To further explore the epigenetic changes in nasopharyngeal carcinoma (NPC), methylation-sensitive arbitrarily primed PCR was performed on NPC biopsies and nontumor nasopharyngeal samples. We have shown mainly two DNA fragments that appeared to be differentially methylated in NPCs versus nontumors. The first, defined as hypermethylated, corresponds to a CpG island at the 5′-end of the tetratricopeptide repeat domain 40 (TTC40) gene, whereas the second, defined as hypo-methylated, is located on repetitive sequences at chromosomes 16p11.1 and 13.1. Thereafter, the epigenetic alteration on the 5′-TTC40 gene was confirmed by methylation-specific PCR, showing a significant aberrant methylation in NPCs, compared to nontumors. In addition, the bisulfite sequencing analysis has shown a very high density of methylated cytosines in C15, C17, and X666 NPC xenografts. To assess whether TTC40 gene is silenced by aberrant methylation, we examined the gene expression by reverse transcription-PCR. Our analysis showed that the mRNA expression was significantly lower in tumors than in nontumors, which is associated with 5′-TTC40 gene hypermethylation. In conclusion, we found that the 5′-TTC40 gene is frequently methylated and is associated with the loss of mRNA expression in NPCs. Hypermethylation of 5′-TTC40 gene might play a role in NPC development; nevertheless, other studies are needed

Quantitative analysis of BCL2 mRNA expression in nasopharyngeal carcinoma: an unfavorable and independent prognostic factor

Programmed cell death plays a vital role in a wide variety of physiological processes. Defects in apoptotic cell death contribute to neoplastic diseases by preventing or delaying normal cell death. BCL2 (Bcl-2) is an anti-apoptotic gene with marked up-regulation in various malignancies, such as breast cancer, in which expression of the BCL2 protein has been proposed as a prognostic tumor biomarker. The purpose of the current study was to investigate mRNA expression of the BCL2 gene in nasopharyngeal carcinoma (NPC) biopsies and assess its prognostic value. For this purpose, total RNA was isolated from 89 malignant and hyperplastic nasopharyngeal biopsies from Tunisian patients. After testing the quality of the extracted RNA, cDNA was prepared by reverse transcription. A highly sensitive real-time PCR methodology for BCL2 mRNA quantification was developed using SYBRA (R) Green chemistry. GAPDH served as an endogenous control gene. Relative quantification analysis was performed using the comparative C (T) (2(-a dagger a dagger CT)) method. High BCL2 mRNA levels were detected in advanced-stage nasopharyngeal tumors (p = 0.030). Furthermore, BCL2 mRNA expression was strongly associated with lymph node involvement (p = 0.009) and presence of distal metastases (p = 0.013). Survival analysis demonstrated that patients with BCL2-positive nasopharyngeal tumors have significantly shorter disease-free and overall survival (p = 0.011 and p = 0.028, respectively). The major contribution of the current study is the quantification and evaluation, for the first time, of the prognostic significance of the BCL2 mRNA expression in nasopharyngeal carcinoma (NPC) patients. Our results suggest that mRNA expression levels of BCL2 may represent a novel unfavorable and independent tumor biomarker for nasopharyngeal carcinoma