Oridonin inhibits the occurrence and development of colorectal cancer by reversing the Warburg effect via reducing PKM2 dimer formation and preventing its entry into the nucleus

Abstract

Background: The Warburg effect is prevalent in human cancer. Oridonin (ORI) has excellent anticancer effects, but its exact anticancer mechanism is still unclear.

Methods: CCK8, EdU, and flow cytometry assay were performed to detect the effect of ORI on cell viability, proliferation and apoptosis, respectively. RNA-seq was carried out to search the underlying mechanisms. Total PKM2, dimeric PKM2, nuclear PKM2 was detected by Western blot. The epidermal growth factor receptor/extracellular signal regulated kinase (EGFR/ERK) signaling was assayed. The binding ability of Importin-α5 to PKM2 was performed by Co-IP experiments. The effect of ORI combined with cysteine (Cys) or fructose-1, 6-diphosphate (FDP) on cancer cells was detected. Mouse xenograft model was established to confirm the molecular mechanisms in vivo.

Results: ORI inhibited viability, proliferation and promoted apoptosis of CRC cells. RNA-seq revealed ORI attenuated the Warburg effect in cancer cells. ORI reduced dimeric PKM2 and prevented it from entering the nucleus. ORI did not affect the EGFR/ERK signaling, but reduced Importin-α5 binding to the PKM2 dimer. Cys or FDP reversed or enhanced the effect of ORI. Animal model assay confirmed the molecular mechanisms in vivo.

Conclusions: Our study first shows that ORI could have anticancer activity by inhibiting the Warburg effect as a novel activator of PKM2.

Keywords: Colorectal cancer; Oridonin; PKM2; Warburg effect.