The growth arrest special 5 (GAS5) is known to be involved in various cancers. However, its expression regulation remains unclear. Polymorphisms in the promoter region of GAS5 may affect its expression and be associated with cancer susceptibility. In this research, we first evaluated the association of a 5-base pair indel polymorphism (rs145204276) in the promoter region of GAS5 with hepatocelluar carcinoma (HCC) susceptibility in Chinese populations. Logistic regression analysis showed that the deletion allele of rs145204276 significantly increased the risk of HCC in two independent case control sets (1034 HCC and 1054 controls). Further genotype-phenotype association analysis revealed that the deletion allele was markedly correlated with higher expression of GAS5 in HCC tissues. The luciferase activity analysis in an in vitro reporter gene system suggested that the deletion allele improved an increased expression of GAS5 in three hepatoma cell lines. Intriguingly, overexpression of GAS5 displayed an anti-apoptosis effect in HCC cell lines, GAS5 knockdown could partially revert this anti-apoptosis effect, suggesting that GAS5 may act as a proto-oncogene in HCC, in contrast with its inhibitory role in other cancers. Further pyrosequencing revealed that the genotypes of rs145204276 were associated with methylation status of GAS5 promoter region. Taken together, our findings provided evidence that rs145204276 may contribute to hepatocarcinogenesis by affecting methylation status of the GAS5 promoter and subsequently its transcriptional activity thus serving as a potential therapy target for HCC.

KCNQ1 overlapping transcript 1 (KCNQ1OT1), a long noncoding RNA responsible for silencing a cluster of genes in cis, has been shown to be involved in multiple cancers. However, much remains unclear of how KCNQ1OT1 contributes to carcinogenesis. By thoroughly analyzing 510 hepatocellular carcinoma (HCC) cases and 1014 healthy controls in a Chinese population, we identified a novel short tandem repeat (STR) polymorphism (rs35622507) within the KCNQ1OT1 coding region and evaluated its association with HCC susceptibility. Logistic regression analysis showed that compared with individuals carrying the homozygote 10-10 genotype, those heterozygote subjects who carry only one allele 10 had a significantly decreased risk of HCC (adjusted odds ratio [OR]=0.67, 95% confidence interval [CI]=0.53-0.86, p=0.0009), with the risk decreased even further in those without allele 10 (adjusted OR=0.38, 95% CI=0.21-0.69, p=0.0005). Furthermore, genotype-phenotype correlation studies using four hepatoma cell lines support a significant association between STR genotypes and the expression of KCNQ1OT1. Cell lines without allele 10 conferred a 20.9-33.3-fold higher expression of KCNQ1OT1. Meanwhile, KCNQ1OT1 expression was reversely correlated with the expression of the cyclin-dependent kinase inhibitor 1C (CDKN1C), a tumor suppressor gene located within the CDKN1C/KCNQ1OT1 imprinted region, in three hepatoma cell lines. Finally, in silico prediction suggested that different alleles could alter the local structure of KCNQ1OT1. Taken together, our findings suggest that the STR polymorphism within KCNQ1OT1 contributes to hepatocarcinogenesis, possibly by affecting KCNQ1OT1 and CDKN1C expression through a structure-dependent mechanism. The replication of our studies and further functional studies are needed to validate our hypothesis and understand the roles of KCNQ1OT1 polymorphisms in predisposition for HCC.

Hepatocellular carcinoma (HCC) is the most common primary hepatic malignancy, and multiple host genetic factors are believed to contribute to HCC development. The small G protein signaling modulator 3 (SGSM3) has been shown to be associated with small G protein coupled receptor signal transduction pathway, suggesting a potential role in HCC susceptibility. We carried out a case-control study in a Chinese population (502 cases and 513 controls) to determine whether the 4-bp insertion/deletion polymorphism (rs56228771) in 3' untranslated region of SGSM3 could affect HCC susceptibility. Logistic regression analysis showed that compared with the del/del genotype, the ins/del genotype of rs56228771 was associated with a significantly decreased risk of HCC [adjusted odd ratio = 0.55, 95% confidence interval (CI) = 0.42-0.73, P = 1.93 × 10(-5)]. The combined ins/del + ins/ins genotypes contributed to a 45% decreased HCC risk (95% CI = 0.42-0.73, P = 1.03 × 10(-5)). This protective trend was more prominent in the HBsAg-negative subgroup. Furthermore, in vivo experiments showed that mRNA levels of SGSM3 from HCC tumor tissues and adjacent non-HCC tissues were correlated with rs56228771 genotypes. Tissue samples with ins/ins genotype have the highest level of SGSM3, which are 2.85-3.00-fold and 1.46-1.57-fold higher than that with ins/del and del/del genotype, respectively. Similar results were also observed with four common hepatoma cell lines in vitro. In addition, compared with HCC tissues, significantly higher SGSM3 expression was observed in adjacent non-HCC tissues (fold change = 2.48), implying its tumor suppressor roles in HCC. Bioinformatics prediction showed that the insertion allele disrupted a binding site for microRNA (miRNA)-151-5p, which would upregulate SGSM3. Taken together, we provided initial evidence that rs56228771 may contribute to hepatocarcinogenesis, possibly by affecting SGSM3 expression through a miRNA-mediated regulation. The replication of our studies in other populations and functional analysis will further strengthen the underlining mechanism.

It has been reported that miR-21 is upregulated in hepatocellular carcinoma (HCC), and overexpressed miR-21 plays a key role in promoting cell cycle progression, reducing cell death and favoring angiogenesis and invasion. Overexpression of hepatocellular carcinoma, downregulated 1 (HEPN1) exhibits an antiproliferative effect on HepG2 cells, suggesting that silencing of HEPN1 may contribute to carcinogenesis of hepatocytes. In silico analysis revealed that HEPN1 may be a potential target of miR-21. Using quantitative reverse transcription PCR and Western blot, we found that HEPN1 was strikingly downregulated in both mRNA (fold change was 33.5, P < 0.0001) and protein levels in human HCC tumor tissues, in comparison with the adjacent non-tumor tissues. More importantly, the expression level of HEPN1 was inversely correlated with the expression of miR-21 in HCC (R (2) = 0.442, P < 0.0001). The combination between the 3' untranslated region (UTR) of HEPN1 with miR-21 was experimentally verified by a miRNA luciferase reporter approach. The suppressed cell proliferation upon stimulation of miR-21 inhibitor could be partially abolished by knocking down HEPN1, so inhibition of miR-21 expression in HCC cells profoundly suppressed cell proliferation partially by upregulating HEPN1 expression. Taken together, the current study suggested an underlying mechanism that miR-21 directly target HEPN1 and inhibit its expression during the carcinogenesis of HCC. HEPN1 may thus be a candidate as a therapeutic target for patients with HCC.

Background PTPN11, which encodes tyrosine phosphatase Shp2, is a critical gene mediating cellular responses to hormones and cytokines. Loss of Shp2 promotes hepatocellular carcinoma (HCC), suggesting that PTPN11 functions as a tumor suppressor in HCC tumorgenesis. The aim of this study was to evaluate the effects of the short tandem repeat (STR) polymorphism (rs199618935) within 3'UTR of PTPN11 on HCC susceptibility in Chinese populations.Methodology/Principal FindingsWe analyzed the associations in 400 patients from Jiangsu province of China, validating the findings in an additional 305 patients from Shanghai of China. Unconditional logistic regression was used to analyze the association between rs199618935 and HCC risk. Additional biochemical investigations and in-silico studies were used to evaluate the possible functional significance of this polymorphism. Logistic regression analysis showed that compared with individuals carrying shorter alleles (11 and 12 repeats), those subjects who carry longer alleles (13 and 14 repeats) had a significantly decreased risk of HCC [adjusted odds ratio (OR)  = 0.63, 95% confidence interval (CI)  = 0.53–0.76, P = 2.00×10−7], with the risk decreased even further in those carrying allele 15 and 16 (adjusted OR = 0.46, 95% CI = 0.34–0.62, P = 1.00×10−7). Biochemical investigations showed that longer alleles of rs199618935 conferred higher PTPN11 expression in vivo and in vitro. The altered luciferase activities in reporter gene system suggested that STR regulation of PTPN11 expression could be a transcriptional event. Finally, in-silico prediction revealed that different alleles of rs199618935 could alter the local structure of PTPN11 mRNA.Conclusions/SignificanceTaken together, our findings suggested that the STR polymorphism within PTPN11 contributes to hepatocarcinogenesis, possibly by affecting PTPN11 expression through a structure-dependent mechanism. The replication of our studies and further functional studies are needed to validate our findings.