Fig. 2

SIRT5 is required for proliferation and regulates cell cycle and apoptosis in colorectal cancer cells. a, b Growth curves of HCT116 (a) and LoVo (b) cells transfected with two different SIRT5 short interfering RNAs (siRNAs; blue lines) or control siRNA (red line). Results are presented as mean ± SD of five independent samples. ANOVA with Tukey’s test. Western blotting was performed to validate the knockdown efficiency. c, d Flow cytometric assay based on phycoerythrin-conjugated Annexin V staining showing the increased apoptosis of HCT116 and LoVo cells at 48 h post transfection with SIRT5 siRNAs. Representative fluorescence-activated cell sorting (FACS) images are shown in c. Data in c were quantified (d). e, f G2-M phase and S phase arrest were detected in SIRT5-knockdown HCT116 and LoVo cells (e). Data in e were quantified (f). Results in d and f are presented as mean ± SD of three independent samples. Student’s t-test for d. ANOVA with Tukey’s test for f. *P < 0.05, **P < 0.01, and ***P < 0.001. g Western blotting analysis showing increased levels of cleaved caspase 3, caspase 8, caspase 6, PARP, and γH2AX, and altered levels of cell cycle regulators in SIRT5-silenced HCT116 and LoVo cells