Objective Although ketogenic diet (KD) has been studied its certain anti-tumor effect by basic research and clinical trials, the specific molecular targets or indications which verify its anti-tumor activity are lack. In this study, we examined the expression of different ketolytic key enzymes to identify the sensitivity of KD in tumor cells. MethodsExpression of genes encoding 3-hydroxybutyrate dehydrogenase 1 (BDH1) and succinyl-CoA: 3-oxoacid CoA transferase 1 (OXCT1) have been determined in 33 human cancer cell lines by quantitative RT-PCR. HeLa cell and pan-1 cell were selected with high expressing and low expressing two enzymes respectively. Proliferation of HeLa and PANC-1 cells was determined by using a hand-held automatic cell counter after cultured in low glucose medium with or without DL-β-Hydroxybutyric acid sodium salt (βHB). BDH1 and OXCT1 were knocked down in HeLa cells by lentivirus-mediated RNA interference and established HeLa and PANC-1 cell xenograft tumors models in BALB/C nude mice to identify the sensitivity of KD in anti-tumor therapy. Results Compared to control group, proliferation of HeLa and PANC-1 cells in low glucose (LG) was significantly inhibited. Howevere, proliferation of HeLa cells was significantly increased, while added βHB into LG group, but there was no significant effect on proliferation of PANC-1 cells. Animal experiments demonstrated that KD inhibited growth of PANC-1 cell xenograft tumors dramatically, but no effect on the growth of HeLa xenograft tumor. Down-regulation of both BDH1 and OXCT1 in HeLa cells rendered their sensitivity to KD in vitro and in vivo. ConclusionsTumors with low expression of ketolytic enzymes which are not obviously induced gene expression are sensitive to ketogenic metabolic therapy.