OBJECTIVETo explore the role of SIRT3 in regulating the proliferation of hepatocellular carcinoma (HCC) cells in vitro.

METHODSThe protein expression of SIRT3 in 2 normal liver tissues, 2 immortalized hepatocyte lines, and 3 HCC cell lines was determined with Western blotting. SIRT3 overexpression and knockdown in HCC cells were induced by transfection with a vector expressing SIRT3 and a siRNA construct targeting SIRT3, respectively. The efficiency of SIRT3 overexpression and knockdown was detected by Western blot and qRT-PCR, respectively. The proliferation of the transfected HCC cells was examined using Trypan blue exclusion assay, and the cellular DNA synthesis was tested using EdU incorporation assay. The colony-forming ability of the cells was analyzed by colony formation assays.

RESULTSSIRT3 expression was significantly lower in the 3 HCC cell lines than in immortalized hepatocytes and normal liver tissues. SIRT3 overexpression in HCC cells significantly lowered the cell proliferation by 51%-61% (P<0.001), reduced cellular DNA synthesis by 57% (P<0.05), and inhibited colony formation of the cells. SIRT3 knockdown significantly increased the proliferation of HCC cells by 51%-61% (P<0.01) and enhanced DNA synthesis by 137%-149% (P<0.01).

CONCLUSIONSSIRT3 plays a inhibitory role in regulating the proliferation of HCC cells in vitro.