Sorafenib-Mediated Apoptotic And Autophagic Cell Death Is Increased By Carnosic Acid And A Vitamin D2 Analog In Hepatocellular Carcinoma (Hcc)

Hepatocellular carcinoma (HCC) is the third most common cause of cancer mortality worldwide. Its incidence is increasing, and currently there is no curative therapy for it in advanced cases. Sorafenib (Sf), a multikinase inhibitor, is an FDA approved drug for the treatment of unresectable hepatomas, but the improvement in patient survival is very short, so new approaches are needed to supplement the existing regimens. In this study we show that the addition of a plant antioxidant Carnosic acid (CA) and a vitamin D2 derivative Doxercalciferol (D2) to Sf can markedly enhance its cytotoxic effect on HCC cell lines Huh7 (Sf-sensitive) and HCO2 (partially Sf-resistant). In contrast, similar combinatorial treatment of Hu1545 cells (immortalized human hepatocytes) results in only a minimal increase in cell death (CD). The combination Sf-CA/D2 increases HCC cell death by enhancing both apoptosis and cytotoxic autophagy (AuPh). Apoptosis was shown by Annexin V binding analysis and by the increased levels of apoptosis-related proteins BIM, cleaved caspases 9 and 3. AuPh was demonstrated by increased cytoplasmic vacuolation and elevated protein levels of Beclin1, Atg3, and LC3-II. Individually, both CA and D2 enhance Sf-induced CD, but CA produces the predominant effect. These effects were significantly reduced by the addition of the Caspase 3 inhibitor Z-DEVD-fmk or the AuPh inhibitor Chloroquine, and by Beclin1 depletion. A pilot experiment with mice bearing a Huh7 HCC cell xenograft showed markedly increased survival of the animals when CA was added to Sf. These results suggest that CA alone or with D2 may increase the survival of Sf-treated HCC patients. Supported by NIH grants 1R01DK110024 (to CL) and 5R01 44722-27 (to GPS). Citation Format: Xuening Wang, Qunfeng Wu, Kien Pham, Aesis Luna, Michael Danilenko, Chen Liu, George P. Studzinski. Sorafenib-mediated apoptotic and autophagic cell death is increased by carnosic acid and a vitamin D2 analog in hepatocellular carcinoma (HCC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1811.