PKM2 is the target of proanthocyanidin B2 during the inhibition of hepatocellular carcinoma

Abstract

Background The treatment for advanced primary hepatocellular carcinoma (HCC) is sorafenib (SORA), while HCC has become increasingly drug resistant with enhanced aerobic glycolysis. The present study aimed to examine the chemotherapeutic effects of a flavonoid proanthocyanidin B2 (PB2) on HCC. Methods Five kinds of HCC cell lines and LO2 were used to test the effect of PB2 on aerobic glycolysis. The proliferation, cell cycle, apoptosis and a xenograft mouse model were analyzed. Lentivirus overexpressed pyruvate kinase M2 (PKM2) or sh-PKM2 was used to verify the target of PB2. The detailed mechanism was investigated by immunofluorescence, co-immunoprecipitation, and western blotting. Results PB2 inhibited the proliferation, induced cell cycle arrest, and triggered apoptosis of HCC cells in vivo and in vitro. PB2 also suppressed glucose uptake and lactate levels via the direct inhibition of the key glycolytic enzyme, PKM2. In addition, PKM2 inhibited the nuclear translocation of PKM2 and co-localization of PKM2/HIF-1α in the nucleus, leading to the inhibition of aerobic glycolysis. Co-treatment with PB2 was also effective in enhancing the chemosensitivity of SORA. Conclusions PB2 inhibited the expression and nuclear translocation of PKM2, therefore disrupting the interaction between PKM2/HSP90/HIF-1α, to suppress aerobic glycolysis and proliferation, and trigger apoptosis in HCC via HIF-1α-mediated transcription suppression. Electronic supplementary material The online version of this article (10.1186/s13046-019-1194-z) contains supplementary material, which is available to authorized users.

Simvastatin re-sensitizes hepatocellular carcinoma cells to sorafenib by inhibiting HIF-1α/PPAR-γ/PKM2-mediated glycolysis

“…However, if compound 3 K was cotreated with Sora + Sim, the up-regulation of PKM2 was decreased slightly, and the expression of HIF-1α and PPAR-γ remained the same as the Sora + Sim group. The effect of co-treatment with DASA 58 (40 μM) was however, opposite to that seen with compound 3 K [29]. The analysis of nuclear fractions also showed that the changes of HIF-1α, PPAR-γ and PKM2 were similar to the total protein when treated with compound 3 K or DASA 58 (Fig.…”

“…Standard colony formation, Hoechst 33342 staining, immunofluorescence staining and flow cytometry analysis for apoptosis were conducted as described previously [29]. The flow cytometry used in the study was FACSCalibur (Becton, Dickinson, Franklin Lakes, NJ, USA), and analyzed by FlowJo software (version 10; FlowJo LLC, Ashland, OR, USA).…”

“…The Co-IP assay was carried out using the Pierce Coimmunoprecipitation Kit (Thermo Scientific, Waltham, MA, USA) and according to manufacturer's protocol, 1 mg of total protein lysate was mixed with 10 μg of primary antibody, or IgG. The results were analyzed by western blotting [29].…”

The microenvironmental and metabolic aspects of sorafenib resistance in hepatocellular carcinoma

“…Key enzymes in glycolysis including PFKFB3, HK2, and PKM2 have been demonstrated overexpression in HCC patients or sorafenibresistant HCC cell lines to increase glycolytic flux and enhance glycolysis [43]. Silencing these enzymes has shown synergetic effect with sorafenib [44][45][46]. In addition, glycolysis under hypoxic environments exhibits high dependency on HIF family, especially in aggressive HCC [47].…”

“…In addition, glycolysis under hypoxic environments exhibits high dependency on HIF family, especially in aggressive HCC [47]. Interestingly, these metabolic enzymes even could directly bind to HIF-1a or forms a positive feedback loop with HIF-1a at transcriptional level [45,48]. Inhibiting glycolysis by specific molecule or by targeting key enzymes of glycolysis is effective strategy to attenuates sorafenib resistance specially under SIH.…”