Background: Homeobox A10 (HOXA10) has been implicated in the development and progression of various human cancers. However, the precise biological functions of HOXA10 in hepatocellular carcinoma (HCC) have not been defined.
Methods: In this study, we examined mRNA expression by quantitative real-time PCR (qRT-PCR) of HOXA10 as well as histone deacetylase (HDAC) and protein levels by Western blot of HOXA10, HDAC1, Cyclin D1, proliferating cell nuclear antigen (PCNA), Survivin and p53 acetylation in HCC tissues and cell lines. We also assessed cell proliferation using Cell Counting Kit-8 (CCK-8) and analyzed cell cycle by flow cytometry. Furthermore, tumor growth of HCC cells in vivo was monitored using the nude mouse xenograft model. Finally, HDAC1 promoter activity and binding in HCC cell lines were detected by luciferase reporter assay and chromatin immunoprecipitation (ChIP), respectively.
Results: We uncovered the elevated expression of HOXA10 in HCC tissues compared to adjacent normal liver tissues. RNA interference-mediated knockdown of HOXA10 inhibited HCC cell proliferation both in vitro and in vivo. HOXA10 knockdown also induced cell cycle arrest at G0/G1 phase and apoptosis, which were accompanied with the reduced expression of Cyclin D1, PCNA and Survivin. Notably, HOXA10 knockdown enhanced p53 acetylation (Lys382), which is crucial to the activation of p53. Likewise, HOXA10 knockdown suppressed the transcription of HDAC1, a potential deacetylase for p53. In line with these observations, HDAC1 downregulation abrogated the effects of HOXA10 overexpression on proliferation, cell cycle progression, apoptosis and p53 acetylation, indicating the role of HDAC1 in mediating HOXA10 functions.
Conclusion: Our results demonstrate that HOXA10 knockdown inhibits proliferation, induces cell cycle arrest and apoptosis in HCC cells by regulating HDAC1 transcription.
Keywords: hepatocellular carcinoma, HOXA10, HDAC1, p53, acetylation