MicroRNAs as therapeutic strategy for hepatitis B virus-associated hepatocellular carcinoma: Current status and future prospects

GAS5 rs2067079 and miR-137 rs1625579 functional SNPs and risk of chronic hepatitis B virus infection among Egyptian patients

Hepatitis B virus (HBV) infection is a significant health issue worldwide.. We attempted to fulfill the molecular mechanisms of epigenetic and genetic factors associated with chronic HBV (CHBV). Expression levels of the lncRNA growth arrest-specific 5 (GAS5) and miR-137 and their corresponding SNPs, rs2067079 (C/T) and rs1625579 (G/T) were analyzed in 117 CHBV patients and 120 controls to investigate the probable association between these biomarkers and CHBV pathogenesis in the Egyptian population. Serum expression levels of GAS5 and miR-137 were significantly down-regulated in cases vs controls. Regarding GAS5 (rs2067079), the mutant TT genotype showed an increased risk of CHBV (p < 0.001), while the dominant CC was a protective factor (p = 0.004). Regarding miR-137 rs1625579, the mutant genotype TT was reported as a risk factor for CHBV (p < 0.001) and the normal GG genotype was a protective factor, p < 0.001. The serum GAS5 was significantly higher in the mutant TT genotype of GAS5 SNP as compared to the other genotypes (p = 0.007). Concerning miR-137 rs1625579, the mutant TT genotype was significantly associated with a lower serum expression level of miR-137 (p = 0.018). We revealed the dysregulated expression levels of GAS5 and miR-137 linked to their functioning SNPs were associated with CHBV risk and might act as potential therapeutic targets.

Hepatitis B virus X protein boosts hepatocellular carcinoma progression by downregulating microRNA-137

BACKGROUND

Hepatocellular carcinoma (HCC) is a frequent diagnosed malignancy. microRNAs (miRs) are involved in various cellular processes during cancer development. This study attempted to probe the miR-based mechanism in hepatitis B virus X protein (HBx) small interfering RNA (siRNA)-treated HCC cells.

METHODS

HBx expression in hepatocyte and HCC cells was detected, and cells with highest HBx expression were screened out and transfected with HBx-siRNAs. Then the effect of HBx on HCC cell proliferation was detected. miRs differentially expressed in HBx-siRNA-transfected MHCC97H cells were analyzed and verified. miR-137 methylation was analyzed by bioinformatics, and miR-137 restoration was detected after Aza treatment. Furthermore, miR-137 methylation in MHCC97H cells with HBx knockdown or HBx overexpression was detected by methylation specific PCR. The targeting relationship between miR-137 and Notch1 was verified. Then the gain-and-loss functions of miR-137 or/and Notch1 were performed to estimate their roles in HCC cell proliferation. The effects of HBx-siRNA and overexpressed miR-137 in vivo were observed by tumor xenograft in nude mice and immunohistochemistry.

RESULTS

HBx-siRNA weakened MHCC97H cell proliferation and tumor growth. miR-137 was highly expressed in HBx-siRNA-treated HCC cells and targeted Notch1. HBx knockdown decreased miR-137 methylation and restored miR-137 expression. miR-137 overexpression prevented HCC cell proliferation and tumor growth, while miR-137 downregulation reversed the repressing effects of HBx-siRNA on HCC cell proliferation. Inhibition of Notch1 reversed HCC cell proliferation induced by miR-137 downregulation.

CONCLUSION

Overexpression of miR-137 blocks HCC cell proliferation in HBx-siRNA-treated MHCC97H cells by targeting Notch1. This study may offer novel target for HCC treatment.

Nuclear IKKα mediates microRNA-7/-103/107/21 inductions to downregulate maspin expression in response to HBx overexpression

Maspin is a tumor suppressor that stimulates apoptosis and inhibits metastasis in various cancer types, including hepatocellular carcinoma (HCC). Our previous study has demonstrated that HBx induced microRNA-7, 103, 107, and 21 expressions to suppress maspin expression, leading to metastasis, chemoresistance, and poor prognosis in HCC patients. However, it remains unclear how HBx elicits these microRNA expressions. HBx has been known to induce aberrant activation and nuclear translocation of inhibitor-κB kinase-α (IKKα) to promote HCC progression. In this study, our data further revealed that nuclear IKKα expression was inversely correlated with maspin expression in HBV-associated patients. Nuclear IKKα but not IKKβ reduced maspin protein and mRNA expression, and inhibition of IKKα reverses HBx-mediated maspin downregulation and chemoresistance. In response to HBx overexpression, nuclear IKKα was further demonstrated to induce the gene expressions of microRNA-7, −103, −107, and −21 by directly targeting their promoters, thereby leading to maspin downregulation. These findings indicated nuclear IKKα as a critical regulator for HBx-mediated microRNA induction and maspin suppression, and suggest IKKα as a promising target to improve the therapeutic outcome of HCC patients.

Several microRNAs could predict survival in patients with hepatitis B-related liver cancer

MicroRNAs as biomarkers play an important role in the tumorigenesis process, including hepatocellular carcinomas (HCCs). In this paper, we used The Cancer Genome Atlas (TCGA) database to mine hepatitis B-related liver cancer microRNAs that could predict survival in patients with hepatitis B-related liver cancer. There were 93 cases of HBV-HCC and 49 cases of adjacent normal controls included in the study. Kaplan–Meier survival analysis of a liver cancer group versus a normal control group of differentially expressed genes identified eight genes with statistical significance. Compared with the normal liver cell line, hepatocellular carcinoma cell lines had high expression of 8 microRNAs, albeit at different levels. A Cox proportional hazards regression model for multivariate analysis showed that four genes had a significant difference. We established classification models to distinguish short survival time and long survival time of liver cancers. Eight genes (mir9-3, mir10b, mir31, mir519c, mir522, mir3660, mir4784, and mir6883) were identified could predict survival in patients with HBV-HCC. There was a significant correlation between mir10b and mir31 and clinical stages (p < 0.05). A random forests model effectively estimated patient survival times.

Latest developments in precancerous lesions of hepatocellular carcinoma

Hepatocarcinogenesis in human chronic liver diseases is a multi-step process in which hepatic precancerous lesions progress into early hepatocellular carcinoma (HCC) and progressed HCC, and the close surveillance and treatment of these lesions will help improve the survival rates of patients with HCC. The rapid development and extensive application of imaging technology have facilitated the discovery of nodular lesions of ambiguous significance, such as dysplastic nodules. Further investigations showed that these nodules may be hepatic precancerous lesions, and they often appear in patients with liver cirrhosis. Although the morphology of these nodules is not sufficient to support a diagnosis of malignant tumor, these nodules are closely correlated with the occurrence of HCC, as indicated by long-term follow-up studies. In recent years, the rapid development and wide application of pathology, molecular genetics and imaging technology have elucidated the characteristics of precancerous lesions. Based on our extensive review of the relevant literature, this article focuses on evidence indicating that high-grade dysplastic nodules are more likely to transform into HCC than low-grade dysplastic nodules based on clinical, pathological, molecular genetic and radiological assessments. In addition, evidence supporting the precancerous nature of large cell change in hepatitis B virus-related HCC is discussed.

Circulating microRNAs as diagnostic and prognostic tools for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive malignancy and the second leading cause of cancer-related deaths worldwide. Conventional biomarkers exhibit poor performance in the surveillance, diagnosis, and prognosis of HCC. MicroRNAs (miRNAs) are a class of evolutionarily conserved small non-coding RNAs that are involved in the regulation of gene expression and protein translation, and they play critical roles in cell growth, differentiation, and the development of various types of cancers, including HCC. Recent evidence revealed the role of miRNAs as potential novel and ideal biomarkers for HCC. miRNAs are released to extracellular spaces, and they are extremely stable in bodily fluids, including serum or plasma, where they are packaged into various microparticles or associated with RNA-binding proteins. Numerous studies have demonstrated that circulating miRNAs have potential applications as minimally invasive biomarkers for HCC diagnosis and prognosis. The present review highlights current understanding of miRNA biogenesis and the origins and types of circulating miRNAs. We summarize recent progress in the use of circulating miRNAs as diagnostic and prognostic biomarkers for HCC. We also discuss the challenges and perspectives of the clinical utility of circulating miRNAs in HCC.

The hepatitis B virus-associated tumor microenvironment in hepatocellular carcinoma

In contrast to a majority of cancer types, the initiation of hepatocellular carcinoma (HCC) is intimately associated with a chronically diseased liver tissue, with one of the most prevalent etiological factors being hepatitis B virus (HBV). Transformation of the liver in HBV-associated HCC often follows from or accompanies long-term symptoms of chronic hepatitis, inflammation and cirrhosis, and viral load is a strong predictor for both incidence and progression of HCC. Besides aiding in transformation, HBV plays a crucial role in modulating the accumulation and activation of both cellular components of the microenvironment, such as immune cells and fibroblasts, and non-cellular components of the microenvironment, such as cytokines and growth factors, markedly influencing disease progression and prognosis. This review will explore some of these components and mechanisms to demonstrate both underlying themes and the inherent complexity of these interacting systems in the initiation, progression, and metastasis of HBV-positive HCC.

Epigenetic therapy as a novel approach in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver malignancy and one with high fatality. Its 5-year survival rate remains low and thus, there is a need for improvement of current treatment strategies as well as development of novel targeted methodologies in order to optimize existing therapeutic protocols. To this end, only recently, it was discovered that its pathophysiology also involves epigenetic alterations in DNA methylation, histone modifications and/or non-coding microRNA patterns. Unlike genetic events, epigenetic alterations are reversible and thus potentially considered to be an alternative option in cancer treatment protocols. In this review, we describe the general characteristics and resulted major alterations of the epigenetic machinery as well as current state of progress of epigenetic therapy (via different single or combinatorial experimental approaches) in HCC.