Epigenetic Regulations Of HDAC5 In Osteosarcoma Cell Proliferation

ObjectiveTo study the effect of histone deacetylase 5 (HDAC 5) on proliferation of osteosarcoma cells and discuss the potential role of HDAC inhibitors in the clinical treatment for osteosarcoma.MethodsPrimary osteosarcoma tissues and distant normal tissues were collected from routine therapeutic surgery at our department. Via reverse transcription polymerase quantitative chain reaction (RT-qPCR) and western blotting, the transcription and expression level of HDAC 5 is determined in osteosarcoma tissues, distant normal tissues and cell lines (U2OS, Saos-2 and MG63). To investigate the role of HDAC 5 in proliferation of osteosarcoma cells, the HDAC 5 gene was overexpressed in U2OS cell lines and RNAi was performed to knock down the expression of HDAC 5 in cell lines. Bromodeoxyuridine (BrdU) analysis was performed to detect the cell numbers. As the oncogene twist 1 plays an essential role in cell growth arrest and apoptosis in tumor, we asked whether overexpression or knockdown of HDAC 5 may affect twist 1 expression.Results1. HDAC 5 expression was obviously upregulated in osteosarcoma tissues as well as U2OS, Saos-2, and MG63 cell lines comparing with normal tissues (P<0.05).2. HDAC 5 overexpression promoted U20S cells proliferation and downregulation of HDAC 5 via RNAi led to a marked decrease in cell number and proliferation in these cells (P<0.01).3. Overexpression of HDAC 5 promoted twist 1 mRNA and protein levels and downregulation of HDAC 5 via RNAi led to a marked decrease in twist 1 expression comparing with control groups (P<0.001). In agreement, HDAC 5 depletion dramatically led to a reduction of twist 1 expression.4. Through carrying out experiments with twist 1 knockdown using siRNA oligos, it suggested that the siRNA rescued cells from the effect of HDAC 5 on cell proliferation in U2OS cells.Conclusion1. HDAC5 in osteosarcoma cells in the regulation of cell proliferation and division. After overexpression of HDAC 5 in the osteosarcoma cell line, the proliferation ability increases significantly and downregulation of HDAC 5 leads to less proliferation ability.2. HDAC5 can through a variety of signal transduction pathways regulating cell proliferation of osteosarcoma, but one of the main way is directly activated oncogenes expression of twistl quantity increase.