HOXD10 Act As A Tumor Suppressor Gene Through Inhibiting ERK Signaling In Hepatocellular Carcinoma

Background: Hepatocellular carcinoma is the fifth most common malignancy and the third leading cause of cancer related death worldwide. The mechanisms underlying the development and progression of HCC remain unclear. Homeobox (HOX) genes encode homeoproteins, which share a common homeodomain and serve as important transcription factors. Homeoproteins play an important role in development and carcinogenesis by modulating cell growth, migration, cell cycle and apoptosis. HOXD10 (homeobox D10) is a member of the homeobox gene family. Dysregulation of Homeobox D10 was found to suppress or promote cancer progression in different cancer types. The function and regulation of Homeobox D10 remain unclear in human hepatocellular carcinoma.Objective: To investigate the expression regulation and function of HOXD10 in HCC.Material and methods: Primary hepatocellular carcinoma samples (117 cases) and normal liver tissues (15 cases) collected from our hospital between 1 July 2010 and 1 January 2014, and 12 hepatocellular cancer cell lines (SNU182, SNU449, HBXF344,SMMC7721, Huh7, HepG2, LM3, PLC/PRF/5, BEL7402, SNU387, SNU475 and Huhl cells) were included in this study. Methylation specific PCR, semi-quantitative RT-PCR and immunohistochemistry were performed to detect the expression of HOXD10 in hepatocellular carcinoma samples and cell lines. Colony formation assay, flow cytometry,transwell, western blot, and chromatin immunoprecipitation assays were employed to explore the function and mechanism of HOXD10 in hepatocellular cancer.Results: HomeoboxD10 was methylated in 76.9% (90/117) of human primary hepatocellular carcinoma samples. HomeoboxDIO methylation was significantly associated with tumor cell differentiation and vessel cancerous embolus (all P < 0.05). The expression of Homeobox D10 was regulated by promoter region methylation. Restoration of Homeobox D10 expression suppressed colony formation, ceii proliferation, invasion and migration, and induced G2/M phase arrest and apoptosis in SMMC7721 and Huh7 cells. In addition, re-expression of Homeobox D10 up-regulated IGFBP3 expression and inhibited ERK1/2 phosphorylation.Conclusion: Homeobox D10 is frequently methylated in human hepatocellular carcinoma, and the expression of Homeobox D10 is regulated by promoter region methylation. Homeobox D10 suppresses human hepatocellular carcinoma progression by inhibiting ERK signaling.