The PKM2 inhibitor shikonin enhances piceatannol‐induced apoptosis of glyoxalase I‐dependent cancer cells

Abstract

AbstractGlyoxalase I (GLO I), a major enzyme involved in the detoxification of the anaerobic glycolytic byproduct methylglyoxal, is highly expressed in various tumors, and is regarded as a promising target for cancer therapy. We recently reported that piceatannol potently inhibits human GLO I and induces the death of GLO I‐dependent cancer cells. Pyruvate kinase M2 (PKM2) is also a potential therapeutic target for cancer treatment, so we evaluated the combined anticancer efficacy of piceatannol plus low‐dose shikonin, a potent and specific plant‐derived PKM2 inhibitor, in two GLO I‐dependent cancer cell lines, HL‐60 human myeloid leukemia cells and NCI‐H522 human non‐small‐cell lung cancer cells. Combined treatment with piceatannol and low‐dose shikonin for 48 h synergistically reduced cell viability, enhanced apoptosis rate, and increased extracellular methylglyoxal accumulation compared to single‐agent treatment, but did not alter PKM1, PKM2, or GLO I protein expression. Taken together, these results indicate that concomitant use of low‐dose shikonin potentiates piceatannol‐induced apoptosis of GLO I‐dependent cancer cells by augmenting methylglyoxal accumulation.