DHMMF, a natural flavonoid from Resina Draconis, inhibits hepatocellular carcinoma progression via inducing apoptosis and G2/M phase arrest mediated by DNA damage-driven upregulation of p21

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and is extremely malignant in nature. It is an important way to discover anti-cancer drugs from natural products at present. (R)-7,3′-dihydroxy-4′-methoxy-8-methylflavane (DHMMF), a natural flavonoid, was isolated from Resina Draconis which is the red resin from Dracaena cochinchinensis (Lour.) S. C. Chen. However, the anti-hepatoma effect and underlying mechanisms of DHMMF remain unclear. Herein, we demonstrated that DHMMF treatment significantly inhibited the proliferation of human hepatoma HepG2 and SK-HEP-1 cells. The IC50 value of DHMMF for HepG2 and SK-HEP-1 cells were 0.67 μM and 0.66 μM, respectively, while the IC50 value of DHMMF for human normal liver LO2 cells was 120.60 μM. DHMMF induced DNA damage, apoptosis, and G2/M phase arrest in HepG2 and SK-HEP-1 cells. Furthermore, the anti-proliferative and pro-apoptotic effects of DHMMF in human hepatoma cells were mediated by the upregulation of p21. Importantly, DHMMF exhibited potent anti-HCC efficacy in a xenograft mice model and an orthotopic mice model of liver cancer. Additionally, the combined administration of DHMMF and polo-like kinase 1 (PLK1) inhibitor BI 6727 showed a synergistic anti-HCC efficacy. Collectively, we demonstrated that DHMMF treatment induced apoptosis and G2/M phase arrest via DNA damage-driven upregulation of p21 expression in human hepatoma cells. DHMMF may serve as a promising drug candidate for HCC treatment, especially for patients of HCC with low p21 expression. Our results also suggested that DHMMF treatment in combination with PLK1 inhibitor may serve as a potential treatment strategy for patients with HCC.