Association of DLC1 gene polymorphism with susceptibility to hepatocellular carcinoma in Chinese hepatitis B virus carriers

Association of deleted in liver cancer-1 gene polymorphism with increased risk of chronicity of disease among Malaysian patients with hepatitis B infection

OBJECTIVE

The aim of this study is to examine the association between genetic variations in deleted in liver cancer 1 (DLC1) gene with progression of the hepatitis B virus (HBV) infection.

METHODS

A total of 623 subjects were included in this study, of whom, 423 were chronic hepatitis B (CHB) patients without liver cirrhosis or hepatocellular carcinoma (HCC), 103 CHB with either liver cirrhosis ± HCC and 97 individuals who had resolved HBV. Two single-nucleotide polymorphisms rs3739298 and rs532841 of DLC1 gene were genotyped using the Sequenom MassARRAY platform.

RESULTS

Our results indicated significant differences between the chronic HBV and resolved HBV groups in genotype and allele frequencies of DLC1-rs3739298 [odds ratio (OR) = 2.23; 95% confidence interval (CI): 1.24-3.99; P = 0.007] and (OR = 1.54; 95% CI: 1.07-2.22; P = 0.021), respectively. Moreover, haplotype analysis revealed significant associations between chronicity of HBV with TG and GA haplotypes (P = 0.041 and P = 0.042), respectively.

CONCLUSION

A significant association exists between the rs3739298 variant and susceptibility to CHB infection.

Significance of genetic variants in DLC1 and their association with hepatocellular carcinoma

DLC1 has been shown to be downregulated or absent in hepatocellular carcinoma (HCC) and is associated with tumorigenesis and development. However, only a small number of studies have focused on genetic variations of DLC1. The present study performed exon sequencing for the DLC1 gene in HCC tissue samples from 105 patients to identify functional genetic variation of DLC1 and its association with HCC susceptibility, clinicopathological features and prognosis. A novel missense mutation and four non-synonymous single nucleotide polymorphisms (SNPs; rs3816748, rs11203495, rs3816747 and rs532841) were identified. A significant correlation of rs3816747 polymorphisms with HCC susceptibility was identified. Compared to individuals with the GG genotype of rs3816747, those with the GA (odds ratio (OR)=0.486; P=0.037) or GA+AA genotype (OR=0.51; P=0.039) were associated with a significantly decreased HCC risk. Furthermore, patients with the GC+CC genotype of rs3816748, the TC+CC genotype of rs11203495 or the GA+AA genotype of rs3816747 had small-sized tumors compared with those carrying the wild-type genotype. No significant association of DLC1 SNPs with the patients' prognosis was found. These results indicated that genetic variations in the DLC1 gene may confer a risk for HCC.

Association of a HLA-DP gene polymorphism with progression of HBV infection

AIM: To explore the association of a HLA-DP gene polymorphism (rs6457617) with progression of hepatitis B virus (HBV) infection.

METHODS: A total of 1009 subjects were enrolled in this study, including 234 asymptomatic chronic HBV carriers (ASC), 300 patients with HBV-related liver cirrhosis (LC), 300 patients with HBV-related hepatocellular carcinoma (HCC), and 175 patients with HBV-related acute liver failure (ALF). The differences in alleles and genotype between the control (ASC) group and case groups (LC, HCC and ALF) were identified using the Taqman assay.

RESULTS: The frequencies of TT, CT and CC genotypes at the rs6457617 locus were 20%, 49.6% and 30% in the case HCC group, which were statistically different from those in the control group (TT: 26%; CT: 51.2%; CC: 22.6%) (χ² = 3.94, P = 0.047, OR = 1.49). The frequency of the C allele differed significantly between the HCC group and ASC group (χ² = 4.98, P = 0.025, OR = 1.21). There were no significant differences in allele frequencies and genotype distributions between the LC and ASC groups, and between the ALF and ASC groups.

CONCLUSION: The C allele at the rs6457617 locus is associated with risk of HCC, and the CC genotype confers susceptibility to HCC. The rs6457617 polymorphism might be involved in the development of HCC.

Role of DLC1 tumor suppressor gene and MYC oncogene in pathogenesis of human hepatocellular carcinoma: potential prospects for combined targeted therapeutics (review)

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death, and its incidence is increasing worldwide in an alarming manner. The development of curative therapy for advanced and metastatic HCC is a high clinical priority. The HCC genome is complex and heterogeneous; therefore, the identification of recurrent genomic and related gene alterations is critical for developing clinical applications for diagnosis, prognosis and targeted therapy of the disease. This article focuses on recent research progress and our contribution in identifying and deciphering the role of defined genetic alterations in the pathogenesis of HCC. A significant number of genes that promote or suppress HCC cell growth have been identified at the sites of genomic reorganization. Notwithstanding the accumulation of multiple genetic alterations, highly recurrent changes on a single chromosome can alter the expression of oncogenes and tumor suppressor genes (TSGs) whose deregulation may be sufficient to drive the progression of normal hepatocytes to malignancy. A distinct and highly recurrent pattern of genomic imbalances in HCC includes the loss of DNA copy number (associated with loss of heterozygosity) of TSG-containing chromosome 8p and gain of DNA copy number or regional amplification of protooncogenes on chromosome 8q. Even though 8p is relatively small, it carries an unusually large number of TSGs, while, on the other side, several oncogenes are dispersed along 8q. Compelling evidence demonstrates that DLC1, a potent TSG on 8p, and MYC oncogene on 8q play a critical role in the pathogenesis of human HCC. Direct evidence for their role in the genesis of HCC has been obtained in a mosaic mouse model. Knockdown of DLC1 helps MYC in the induction of hepatoblast transformation in vitro, and in the development of HCC in vivo. Therapeutic interventions, which would simultaneously target signaling pathways governing both DLC1 and MYC functions in hepatocarcinogenesis, could result in progress in the treatment of liver cancer.

Genetic risk of hepatocellular carcinoma in patients with hepatitis C virus: a case control study

BACKGROUND AND AIM

Chronic hepatitis C virus (HCV) infection is a well known risk factor for hepatocellular carcinoma (HCC). The aim of this study is to elucidate the genetic risk of development and recurrence of HCC in patients with HCV.

METHODS

A total of 468 patients with HCV, including 265 with HCC were enrolled. We genotyped 88 single nucleotide polymorphisms (SNPs) in 81 genes expected to influence hepatocarcinogenesis using the iPLEX assay. Risk of HCC was clarified by stratifying patients into risk groups based on the multiplied odds ratio (MOR) for SNPs associated with HCC, and the cumulative effects on the development and recurrence of HCC were analyzed.

RESULTS

Six SNPs associated with risk of HCC were identified (OR range: 0.29-1.76). These included novel SNPs for hepatocarcinogenesis with HCV CCND2 rs1049606, RAD23B rs1805329, CEP164 rs573455, and GRP78rs430397 in addition to the known SNPs MDM2 rs2279744 and ALDH2 rs671. MOR analysis revealed that the highest risk group exerted about a 19-fold higher relative OR compared with the lowest risk group (P = 1.08 × 10(-5)). Predicted 10-year HCC risk ranged from 1.7% to 96% depending on the risk group and the extent of fibrosis. Recurrence-free survival of radiofrequency ablation-treated HCC in the high risk group (n = 53) was lower than that of low risk group (n = 58, P = 0.038).

CONCLUSION

Single nucleotide polymorphisms of CCND2, RAD23B, GRP78, CEP164, MDM2, and ALDH2 genes were significantly associated with development and recurrence of HCC in Japanese patients with HCV.

Loss of DLC1 is an independent prognostic factor in patients with oral squamous cell carcinoma

Deleted in liver cancer (DLC1), a Rho GTPase-activating protein, was observed to be differentially expressed in oral squamous cell carcinoma in comparison with normal tissues using tissue proteomics. In the current study, we investigated the clinical significance of loss of DLC1 expression in different stages of development of oral squamous cell carcinoma to determine its potential as a biomarker for oral dysplasia and prognosis of oral squamous cell carcinoma. Immunohistochemical analysis of DLC1 expression was carried out in oral squamous cell carcinoma patients (n=214), dysplasia (n=51), hyperplastic squamous mucosa (n=45), and histologically normal oral tissues (n=80), and correlated with clinicopathological parameters and disease prognosis over 91 months for oral squamous cell carcinomas. Loss of DLC1 expression was observed in oral squamous cell carcinoma (64%), oral dysplasia (31%), hyperplastic squamous mucosa (22%), and normal mucosa (16%). Significant loss of DLC1 expression was observed in oral squamous cell carcinomas as compared with dysplasia (P<0.001, odds ratio=3.8, 95% CI=2.0-7.3), suggesting it may be an important event involved in cancer progression. Among oral squamous cell carcinomas, the loss of DLC1 expression was significantly associated with poor prognosis (P=0.021, hazards ratio (HR)=1.8, 95% CI=1.1-2.9). Multivariate analysis revealed loss of DLC1 (P=0.023, HR=2.1, 95% CI=1.2-3.9) and histopathological grade (P=0.015, HR=1.7, 95% CI=1.1-2.7) to be independent predictors for disease-free survival in oral squamous cell carcinoma patients in comparison with known prognostic factors, viz. tumor stage, nodal status, and overall stage. Loss of DLC1 expression emerged as an important biomarker for predicting patients diagnosed with oral dysplasia at high risk of transformation upon future validation in longitudinal studies. Loss of DLC1 expression is a poor prognostic marker for oral squamous cell carcinoma patients.