ABSTRACT
Growing evidence indicates that some tumor suppressive miRNAs are subject to epigenetic modifications during carcinogenesis. Here, we found that a large miRNA cluster of C19MC was upregulated in HCC cells after combined treatment with DNA methylation inhibitor and histone deacetylase inhibitor. MiR-517a and miR-517c were strikingly different from the remaining 41 miRNAs in C19MC. Ectopic expression of MiR-517a and miR-517c inhibited cell proliferation by blocking G2/M transition, whereas down-regulation of miR-517a and miR-517c facilitated cell growth. We further showed Pyk2 is a target of miR-517a and miR-517c and both the miRNAs are downregulated in HCC samples. These data collectively suggest that down-regulation of both miR-517a and miR-517c contribute to HCC development through regulating Pyk2.
Subject(s)
Carcinoma, Hepatocellular/genetics , Cell Proliferation , Focal Adhesion Kinase 2/genetics , Liver Neoplasms/genetics , MicroRNAs/genetics , Azacitidine/analogs & derivatives , Azacitidine/pharmacology , Base Sequence , Carcinoma, Hepatocellular/enzymology , Carcinoma, Hepatocellular/pathology , Cell Line, Tumor , DNA Modification Methylases/antagonists & inhibitors , Decitabine , Down-Regulation , Focal Adhesion Kinase 2/metabolism , G2 Phase Cell Cycle Checkpoints , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Neoplastic , Histone Deacetylase Inhibitors/pharmacology , Humans , Hydroxamic Acids/pharmacology , Liver Neoplasms/enzymology , Liver Neoplasms/pathology , MicroRNAs/metabolism , MicroRNAs/physiology , Multigene Family , Oligonucleotide Array Sequence Analysis , RNA Interference , TranscriptomeABSTRACT
Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and shows a propensity to metastasize and infiltrate adjacent and more distant tissues. HCC is associated with multiple risk factors, including hepatitis B virus (HBV) infection, which is especially prevalent in China. Here, we used exome sequencing to identify somatic mutations in ten HBV-positive individuals with HCC with portal vein tumor thromboses (PVTTs), intrahepatic metastases. Both C:G>A:T and T:A>A:T transversions were frequently found among the 331 non-silent mutations. Notably, ARID1A, which encodes a component of the SWI/SNF chromatin remodeling complex, was mutated in 14 of 110 (13%) HBV-associated HCC specimens. We used RNA interference to assess the roles of 91 of the confirmed mutated genes in cellular survival. The results suggest that seven of these genes, including VCAM1 and CDK14, may confer growth and infiltration capacity to HCC cells. This study provides a view of the landscape of somatic mutations that may be implicated in advanced HCC.
Subject(s)
Carcinoma, Hepatocellular/genetics , Exome , Hepatitis B virus , Hepatitis B/complications , Liver Neoplasms/genetics , Adult , Aged , Aged, 80 and over , Carcinoma, Hepatocellular/secondary , Carcinoma, Hepatocellular/virology , Cell Line, Tumor , Cell Proliferation , Cell Survival , Chromosomes, Human, X/genetics , Cyclin-Dependent Kinases/genetics , DNA-Binding Proteins , Female , Genetic Association Studies , Humans , Liver Neoplasms/pathology , Liver Neoplasms/virology , Male , Middle Aged , Nuclear Proteins/genetics , Polymorphism, Single Nucleotide , Portal Vein/pathology , Sequence Analysis, DNA , Transcription Factors/genetics , Vascular Cell Adhesion Molecule-1/genetics , Venous Thrombosis/genetics , Venous Thrombosis/virologyABSTRACT
Delta-like 1 homolog (DLK1; Drosophila) is a hepatic stem/progenitor cell marker in fetal livers that plays a vital role in oncogenesis of hepatocellular carcinoma (HCC). The aim of this study is to investigate whether DLK1 could serve as a potential therapeutic target against cancer stem/progenitor cells of HCC. DLK1(+) and DLK1(-) cells were sorted by fluorescence-activated cell sorting and magnetic-activated cell sorting, respectively, and then were evaluated by flow cytometry. The biological behaviors of these isolated cells and those with DLK1 knockdown were assessed by growth curve, colony formation assay, spheroid colony formation, chemoresistance, and in vivo tumorigenicity. Adenovirus-mediated RNA interference was used to knockdown the endogenous DLK1. We found that DLK1(+) population was less than 10% in almost all 17 HCC cell lines examined. DLK1(+) HCC cells showed stronger ability of chemoresistance, colony formation, spheroid colony formation, and in vivo tumorigenicity compared with DLK1(-) cells. The DLK1(+) HCC cells could generate the progeny without DLK1 expression. Furthermore, DLK1 knockdown could suppress the ability of proliferation, colony formation, spheroid colony formation, and in vivo tumorigenicity of Hep3B and Huh-7 HCC cells. Our data suggested that DLK1(+) HCC cells have characteristics similar to those of cancer stem/progenitor cells. RNA interference against DLK1 can suppress the malignant behaviors of HCC cells, possibly through directly disrupting cancer stem/progenitor cells, which suggested that DLK1 could be a potential therapeutic target against the HCC stem/progenitor cells.