Abstract 4645: Decursin, a coumarin compound, inhibits the growth of human hepatoma cells involving cell cycle arrest, apoptosis, and autophagy

Abstract

Abstract Although recent advances have been made for the treatment of liver cancer, it still remains the sixth most diagnosed cancer worldwide and second most cause of mortality related to cancer. Decursin, a naturally occurring coumarin compound isolated from Angelica gigas Nakai is known for its hepatoprotective activity. For the first time we show that decursin has strong cytotoxic and growth inhibitory effects against liver cancer cells. Decursin (1-25 μM) resulted in a dose-dependent inhibition of Hep3B cell proliferation by upto 65-85% (p<0.005-0.001) in 24-48 h. Similarly in HepG2 cells, decursin (25-100 μM) decreased cell number by upto 61-74% (p<0.005-0.001) at 24-48 h. Growth inhibition was not due to the cell death in HepG2 cells, whereas, Hep3B cells showed an increased cell death (9-45%; p<0.001). Decursin enhanced sub-G1 population of cells in Hep3B but not in HepG2. Further, decursin induced G1 arrest at lower doses, however, at the higher doses cell death prevailed over cell cycle arrest. A consistent G2/M phase arrest in HepG2 cells at all the time points, however, at 100 μM, there was an induction of S-phase arrest. Decursin strongly decreased the colony forming efficiency of Hep3B cells. Decursin induced both apoptotic and autophagic cell death. In flow cytometry analyses, an increase in the acidic vesicular organelle development was observed at 24 and 48 h in Hep3B cells. Interestingly, in decursin treated HepG2 cells, autophagic induction occurred much later (48 h). This was further validated by MDC staining. Mechanistic studies for cell cycle regulators showed that decursin mediated G1 arrest could be via an increase in p21/cip1. Concomitantly, we observed reduced levels of Cyclin A and B1 and their respective kinases. PCNA, a marker of proliferation showed decreased in expression. Decursin mediated induction of apoptosis involved cleavage of caspase-3 and PARP and reduction in survivin level. This was accompanied by an enhanced Bax/Bcl-2 ratio. Additionally, a potent decrease in the phosphorylation of IGF-IR and its downstream effector Akt, was observed. Decursin increased Erk1/2 phosphorylation, however, it was not associated with cell growth or survival. Collectively, these findings suggest that decursin strongly inhibits liver cancer growth and proliferation involving induction of cell cycle arrest, apoptosis and autophagy and could be further explored and developed as novel treatment option for the hepatic malignancies. Citation Format: Praveen K. Kujur, Dongsool Yim, Rana P. Singh. Decursin, a coumarin compound, inhibits the growth of human hepatoma cells involving cell cycle arrest, apoptosis, and autophagy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4645. doi:10.1158/1538-7445.AM2015-4645