Single nucleotide polymorphism in DNMT3B promoter and its association with hepatocellular carcinoma in a Moroccan population

International audienceHepatocellular carcinoma is a major malignant tumor characterized in all areas by the disparity of risk between genders. The molecular bases of such disparity are still poorly understood. DNA-methyltransferase-3B (DNMT3B) may play an oncogenic role during tumorigenesis, and its genetic variants have been consistently associated with risk of several cancers, but a single study has investigated their roles in hepatocellular carcinoma (HCC). Polymorphisms of the DNMT3B gene may influence its activity on DNA methylation in several cancers, thereby modulating susceptibility to tumorigenesis. To test this hypothesis, we investigated the association between single nucleotide polymorphism -149C>T (rs2424913) in the promoter region DNMT3B and risk of HCC in a Moroccan population. In this case-control study, the DNMT3B SNP was genotyped by polymerase chain reaction-restriction fragment length polymorphism in 96 HCCs patients and 222 healthy controls that matched for age, sex and ethnicity. Overall, we found that, the DNMT3B 149 TT genotype was not significantly associated with increased risk of HCC (adjusted odds ratio (OR), 0.86, 95% CI, 0.41-1.80, P=0.697). Stratification analysis detected, however, a trend towards a profound risk in the female subset of patients (OR=2.04, 95% CI, 0.77-5.42) and a lesser risk for HCV-infected patients (OR=1.33, 95% CI, 0.43-4.17). Our findings contrast with those of previous studies performed in various cancers, which showed that individuals carrying at least one T allele have a significantly increased risk of developing cancer. In addition, we provide genetic evidence for the major difference of HCC risk between men and women. Further mechanistic studies are needed to unravel the underlying molecular mechanisms

Polymorphisms in antioxidant defence genes and susceptibility to hepatocellular carcinoma in a Moroccan population

International audienceReactive oxygen species have been related to the aetiology of cancer as they are known to be mitogenic and therefore capable of tumour promotion. The aim of this study was to assess the role of common variation in three polymorphic genes (MnSOD Ala-9Val, GPX1 Pro198Leu and CAT -262 C > T) coding for antioxidant defence enzymes in modulating individual susceptibility to hepatocellular carcinoma (HCC) using a case-control study (cases = 96 and controls = 222). PCR-RFLP and sequencing methods were used to determine the genotype. Overall, there were no associations between genotypes GPX1 and HCC risk (OR, 1.16; 95% CI, 0.56-2.42; p = 0.685). The MnSOD Ala/Ala and CAT TT genotypes were more frequent in HCC than in control (p = 0.001 and p = 0.072, respectively). Further analyses stratified by gender or HCV infection revealed that men and HCV-infected patients carrying CAT TT genotype had a higher risk to develop HCC when compared with controls (OR = 15.94; 95% CI, 3.48-72.92; p < 0.000001 and 12.01; 95% CI, 0.64-223.63, p = 0.056, respectively). Combined MnSOD Ala/Ala and GPx1 Leu/Leu had a synergistic effect on HCC risk, with an OR of 3.84 (p = 0.029). Furthermore an even more pronounced risk was observed when we combined MnSOD Ala/Ala and CAT TT (OR = 13.60, p = 0.023). It appears that variants in MnSOD, CAT or GPX1 have an influence on HCC risk in this cohort. Furthermore, it is possible that cumulative defects in protection from oxidative stress may result in increased risk of liver cancer in the Moroccan population

Impact of TP53 Codon 72 and MDM2 Promoter 309 Allelic Dosage in a Moroccan Population with Hepatocellular Carcinoma

The paper was presented at the 59th Annual Meeting of the American Association for the Study of Liver Diseases, October 31 - November 4, 2008, San Francisco, CA, USA.International audienceSingle-nucleotide polymorphisms (SNPs) in codon 72 of the TP53 gene (rs1042522) and in the promoter region of the MDM2 gene (SNP309; rs2279744) have been shown to play a role in the predisposition to many cancers. However, these findings were inconsistent in other tumor types, and ethnicity is suspected to be a critical factor influencing the effects of these SNPs on the cancer risk. The aim of the present study was to investigate whether these functional SNPs were associated with an enhanced risk of liver tumorigenesis in Moroccan patients. We have genotyped both polymorphisms in 96 patients with hepatocellular carcinoma (HCC) and 222 controls without HCC matched for age, gender and ethnicity by PCR-RFLP confirmed by sequencing. A joint effect between the MDM2 and TP53 polymorphisms and an increased risk of liver cancer was detected, with the odds ratio for the presence of both MDM2 309GG and TP53 72Pro/Pro genotypes being 10 (95% confidence interval 0.39-255.55). Interestingly, a significant increase in the HCC risk was observed when at least two deleterious alleles were present, indicating an allele dosage effect. There was no evidence for any association with early age of HCC onset when deleterious alleles of MDM2 SNP309 and TP53 Arg72Pro where present. Our findings suggest that the combination of TP53 72Pro and MDM2 309G polymorphisms enhance the risk of developing HCC. These results deserve further confirmation in other populations

The Pro variant of the p53 codon 72 polymorphism is associated with hepatocellular carcinoma in Moroccan population

International audienceAim: Codon 72 polymorphism of the p53 gene has been implicated in cancer risk, and it has been suggested that it may have an impact on the clinical outcome of the disease. Our objective was to evaluate the association between p53 polymorphism at codon 72 and hepatocellular carcinoma (HCC) in the Moroccan population.Methods: Genomic DNA was extracted from peripheral blood cells of 96 patients with HCC and 222 controls without HCC matched for age, gender and ethnicity. Codon 72 polymorphism of p53 was identified by PCR-restriction fragment length polymorphism, confirmed by sequencing.Results: Patients with HCC had higher frequencies of Pro/Pro (13.5% vs. 6.3%, P < 0.02) than controls and consequently a 2.3-fold increased risk of liver cancer development (odds ratio [OR], 2.304; 95% confidence interval [CI], 1.014-5.234). In addition, we found a significant association between the p53Arg72Pro polymorphism and the female gender in HCC. Men with Pro/Pro genotype had a 1.57-fold increased risk for HCC, whereas the corresponding genotype in women had a 4.4-fold increased risk of HCC (OR, 4.4; 95% CI, 1.18-16.42). No correlation between the polymorphism and HCC risk was found when comparing the hepatitis C virus (HCV)-positive cases to HCV-positive controls. However, HCV-negative subjects and Pro/Pro genotype had a 3.31-fold increased risk for HCC.Conclusion: These results provide evidence that p53 polymorphism at codon 72 is a modifier of hepatocarcinogenesis, especially in women and HCV-negative subjects

Associations de variations génétiques des coactivateurs transcriptionnels EP300 et PCAF avec le carcinome hépatocellulaire

International audienceBackground and aims: Hepatocellular carcinoma (HCC) is a common cause of death by cancer worldwide. In Morocco, HCC is characterized by few mutations and a mild chromosome instability suggesting that epigenetic changes may represent the driving force of tumorigenesis in the region. Recently, three studies looked for an association between EP300 or PCAF polymorphisms and cancer but there is a conspicuous lack of data regarding these histone acetyltransferase (HAT) variants and HCC development. The aim of the current study was to assess the impact of the Ile997Val in EP300 and Asn386Ser in PCAF polymorphisms on the risk of HCC.Materials and methods: We performed a case-control study comparing 94 cases with HCC and 220 matching controls. Sequencing methods were used to determine the genotype at the Ile997Val and Asn386Ser on EP300 and PCAF.Results: We found an overall association between genotypes Val/Val in EP300 and HCC risk (OR, 3.03; 95% CI, 1.08-8.47; P=0.028). Population stratifications revealed a trend or significantly higher risks of HCC development for women and HCV-negative patients carrying the EP300 Val/Val genotype (OR, 4.06; 95% CI, 0.71-23.36; P=0.09 and OR, 4.48; 95% CI, 1.04-19.14; P=0.02, respectively). The PCAF Ser/Ser genotype at codon 386 was more frequent in HCC cases than in control group (P=0.03). We observed trends for higher risk of HCC among men and/or HCV-negative patients carrying Ser/Ser genotype when compared with controls (OR, 10.62; 95% CI, 0.50-225.13 and OR, 11.78; 95% CI, 0.47-295.56, respectively).Conclusion: It appears that variants of the transcriptional coactivator genes (EP300 and PCAF) may influence HCC risk in populations with low mutations or chromosomal instability rates. Additional surveys are warranted to confirm this first report

Prevalence of Common HFE and SERPINA1 Mutations in Patients with Hepatocellular Carcinoma in a Moroccan Population

International audienceBackground: Hereditary hemochromatosis and SERPINA1 mutation were reported to affect liver functions. Our objective was to estimate the prevalence of HFE and SERPINA1 (formerly known as alpha1-antitrypsin, AAT) mutations and assess their influence on hepatocellular carcinoma development.Methods: This study included 222 controls and 96 cases with hepatocellular carcinoma. PCR-RFLP was used to characterize S and Z alleles in SERPINA1, as well as C282Y/H63D alleles of HFE.Results: In healthy subjects and hepatocellular carcinoma patients as well, no homozygotes for the C282Y mutation were found. In controls, heterozygosity and homozygosity for the H63D mutation were 27 and 0.9%, respectively. Among patients, homozygosity for the H63D mutation was 3.1%, whereas heterozygosity for C282Y and H63D was 2.1 and 35.4%, respectively. Interestingly, albeit it does not reach significance (p=0.062), H63D was more prevalent in hepatocellular carcinoma patients than in controls (38.5 vs. 27.9%, respectively). The association was stronger when considering only male patients with hepatocellular carcinoma (47.1 vs. 23.6, p=0.001). Allele frequencies of S and Z in controls were 0.45% (95% CI=0.2-1.07) and 0.22% (95% CI=0.2-0.6), respectively, and 1 for S and 0% for Z in HCC. No significant difference was found between cases and controls.Conclusions: We provide a novel appraisal of HFE and SERPINA1 mutations prevalence in the Moroccan population. Results are consistent with the worldwide spread of the H63D and S mutation and the north European restriction of the C282Y and Z. Our results show that H63D carriage is increased among hepatocellular carcinoma patients, suggesting that it may confer an increased susceptibility to hepatocellular carcinoma even in a heterozygous state. On the contrary, HFE C282Y and SERPINA1 mutations do not contribute to hepatocellular carcinoma development

Genetic polymorphism in the manganese superoxide dismutase gene is associated with an increased risk for hepatocellular carcinoma in HCV-infected Moroccan patients

International audienceHepatocellular carcinoma (HCC) ranks among the 10 most common cancers worldwide. The main risk factors for its development are hepatitis B and C virus infections. Hepatitis B and C viruses induce chronic inflammation and oxidative stress that could predispose a cell to mutagenesis and proliferation. Manganese superoxide dismutase (MnSOD) catalyses the detoxification of free radicals, thus playing a crucial role in the protection against damage. A valine (Val) to alanine (Ala) substitution at amino acid 9, mapping within the mitochondrion-targeting sequence of the MnSOD gene, has been associated with an increased cancer risk. The aim of our study was to investigate a possible association of the Val/Ala-MnSOD polymorphism and HCC development in Moroccan patients. Genotypes were determined by means of PCR and RFLP analysis in 96 patients with HCC and 222 control subjects matched for age, sex, and ethnicity. Homozygous Ala/Ala carriers were 31% in the cases and 18% in the controls, which corresponds to an odds ratio (OR) of 2.89, with a 95% confidence interval (CI) of 1.47-5.68. Stratification into subgroups based on HCV infection status revealed an even more increased risk for homozygous Ala/Ala carriers with hepatitis C infection (38.2% in the cases versus 14.8% in the control subjects OR, 5.09; 95% CI, 1.76-14.66). Our findings provide further evidence of an association between the Ala-9Val MnSOD polymorphism and HCC occurrence in hepatitis C virus-infected Moroccan patients

MDM2 SNP309T>G polymorphism and risk of hepatocellular carcinoma: A case–control analysis in a Moroccan population

International audienceBackground: The Murine double minute 2 (MDM2) gene encodes a negative regulator of the p53 tumor suppressor protein. A single nucleotide polymorphism (SNP) in the MDM2 promoter (a T to G exchange at nucleotide 309) has been reported to produce accelerated tumor formation. The aim of this study was to investigate whether this functional SNP is associated with an enhanced risk of liver tumorigenesis in Moroccan patients. Methods: The study consisted in the comparison of 96 hepatocellular carcinomas (HCC) cases and 222 controls without HCC matched for age, gender and ethnicity. PCR–RFLP and sequencing methods were used to determine the genotype at the MDM2 SNP309T>G locus. Results: Overall, our results indicate that the GG genotype of SNP309 is significantly associated with an increased risk of HCC (odds ratio, OR = 2.60, 95% CI, 1.08–6.28). Interestingly, despite a wide range of confidence interval, there is a trend associating the GG genotype with a high risk of HCC in males (OR = 3.31; 95% CI, 0.93–11.82) and in HCV-infected patients (OR = 3.7; 95% CI, 0.82–16.45). By contrast, no association between age at diagnosis and MDM2 SNP309 genotypes was observed in HCC patients (P = 0.610). Conclusion: Our findings suggest that the MDM2 309T>G polymorphism is an important modulator of hepatocellular carcinoma development in Moroccan patients

TP53 R72P polymorphism modulates DNA methylation in hepatocellular carcinoma.

International audienceHepatocellular carcinoma (HCC) is characterized by widespread epidemiological and molecular heterogeneity. Previous work showed that in the western part of North Africa, a region of low incidence of HCC, mutations are scarce for this tumor type. As epigenetic changes are considered possible surrogates to mutations in human cancers, we decided, thus, to characterize DNA methylation in HCC from North-African patients. A set of 11 loci was investigated in a series of 45 tumor specimens using methylation-specific and combined-bisulfite restriction assay PCR. Results obtained on clinical samples were subsequently validated in liver cancer cell lines. DNA methylation at tumor suppressor loci is significantly higher in samples displaying chromosome instability. More importantly, DNA methylation was significantly higher in Arg/Arg when compared to Pro/Pro genotype carriers at codon 72 rs1042522 of TP53 (65% vs 20% methylated loci, p = 0.0006), a polymorphism already known to affect somatic mutation rate in human carcinomas. In vitro experiments in cell lines indicated that enzymes controlling DNA methylation were differentially regulated by codon 72 Arg or Pro isoforms of p53. Furthermore, the Arg72-carrying version of p53 was shown to re-methylate DNA more rapidly than the pro-harboring isoform. Finally, Pro-carrying cell lines were shown to be significantly more resistant to decitabine treatment (two-fold, p = 0.005). Our data suggest that Arg72Pro polymorphism in a WT p53 context may act as a primary driver of epigenetic changes in HCC. It suggests, in addition, that rs1042522 genotype may predict sensitivity to epigenetic-targeted therapy. This model of liver tumorigenesis that associates low penetrance genetic predisposition to epigenetic changes emerges from a region of low HCC incidence and it may, therefore, apply essentially to population living in similar areas. Surveys on populations submitted to highly mutagenic conditions as perinatally-acquired chronic hepatitis B or aflatoxin B1 exposure remained to be conducted to validate our observations as a general model