title: MTSS1, a novel target of DNA methyltransferase 3B, functions as a tumor suppressor in hepatocellular carcinoma.
abstract: DNA methyltransferase 3B (DNMT3B) mediates gene silencing via epigenetic mechanisms during hepatocellular carcinoma (HCC) progression. We aimed to identify novel targets of DNMT3B and their potential regulatory mechanisms in HCC. Metastasis suppressor 1 (MTSS1) was one of the DNMT3B targets and selected for further study. DNMT3B overexpression was detected in 81.25% of clinical HCC specimens and was negatively associated with MTSS1 in HCC cells and clinical samples. The underlying mechanism by which DNMT3B silences MTSS1 was studied using a combination of methylation-specific polymerase chain reaction (PCR) and bisulfite genome sequencing, chromatin immunoprecipitation-PCR and luciferase reporter assays. We found that the MTSS1 promoter region was sparsely methylated, and the methylation inhibitors failed to abolish DNMT3B-mediated MTSS1 silencing. DNMT3B protein bound directly to the 5'-flanking region (-865/-645) of the MTSS1 gene to inhibit its transcription. The functional role of MTSS1 was investigated using in vitro and in vivo tumorigenicity assays. As a result, MTSS1 exerted tumor suppressor effects and arrested cells in the G2/M phase, but not the G1/S phase of the cell cycle when it was depleted or overexpressed in HCC cells. Taken together, MTSS1, a novel target of DNMT3B, is repressed by DNMT3B via a DNA methylation-independent mechanism. MTSS1 was further characterized as a novel tumor suppressor gene in HCC. These findings highlight how DNMT3B regulates MTSS1, and such data may be useful for the development of new treatment options for HCC.
authors: The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Department of Medical Genetics and Developmental Biology, Medical School of Southeast University, Nanjing, China. fanh@seu.edu.cn
authors: H
authors: H
authors: Fan
authors: L
authors: L
authors: Chen
authors: F
authors: F
authors: Zhang
authors: Y
authors: Y
authors: Quan
authors: X
authors: X
authors: Su
authors: X
authors: X
authors: Qiu
authors: Z
authors: Z
authors: Zhao
authors: K L
authors: KL
authors: Kong
authors: S
authors: S
authors: Dong
authors: Y
authors: Y
authors: Song
authors: T H M
authors: TH
authors: Chan
authors: X-Y
authors: XY
authors: Guan
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D059447:Cell Cycle Checkpoints / Q000235:genetics; D045744:Cell Line, Tumor; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D000097584:DNA Methyltransferase 3B
chemical_list: D004248:DNA (Cytosine-5-)-Methyltransferases; D004273:DNA, Neoplasm; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D000097584:DNA Methyltransferase 3B; C486778:MTSS1 protein, human