Abstract 1241: Podophyllotoxin acetate (PA) as an anti-cancer drug candidate regulates various malignancy traits of non-small cell lung cancer

Here, we reported that podophyllotoxin acetate (PA) showed various aniti-cancer effects: induction of several cell death pathways, inhibition of γ-ionizing radiation (IR)-induced cancer invasion, chemo-sensitizer effect with topoisomerase (TOP) inhibitors against non-small cell lung cancer (NSCLC) cell lines as follows. (1) Stimulation of cell death via various mechanisms. First, PA dose-dependently induced cell cycle arrest at G2/M phase, as shown by accumulation of the mitosis-related proteins, p21, survivin and aurora B. This arrest was due to the PA-induced inhibition of microtubule polymerization that related to DNA damage (reflected by accumulation of γ-H2AX) resulting induction of intrinsic/extrinsic damage apoptotic pathways. PA also activated the pro-apoptotic ER stress pathway, as evidenced by increased expression levels of BiP, CHOP, IRE1-a, phospho-PERK, and phospho-JNK. Next, PA induced autophagy that reflected the expression of beclin-1, Atg3, Atg5 and Atg7, and the cleavage of LC3. (2) Inhibition of IR-induced cancer invasion. IR increased the invasion/migration of A549 cells, and this effect was decreased by PA treatment that the expressions/activities of matrix metalloprotase (MMP) -2, MMP-9, and vimentin, suggesting that PA could block the IR-induced epithelial-mesenchymal transition (EMT). In this study, we also identified IR-induced new signaling pathway, EGFR - p38/ERK - CREB-1/STAT3 - EMT pathway, that was inhibited by PA. (3) Chemo-sensitizer effect conjugated with TOP inhibitors - etoposide (Eto) and camptothecin (Cpt). Combination Index (CI) values of the combinations showed synergistic effects between PA and topoisomerase inhibitors. Combination with PA and Eto/Cpt promotes disruption of dynamics of actin filaments, which subsequently enhanced apoptotic cell death that accompanied to increased phosphorylation of p38. We also observed these combinations also inhibited activation of CREB-1, synergistically. Therefore, this study indicated that PA functions as a chemosensitizer by enhancing apoptosis through activation of p38/caspases apoptotic axis and suppression of CREB-1.Taken together; these results suggest PA is a new anti-cancer drug candidate that could control several malignancy traits of cancer including uncontrolled cell cycle and IR-induced invasion. Citation Format: Jeong Hyun Cho, Wan Gi Hong, Sang-Gu Hwang, Hong-Duck Um, Jong Kuk Park. Podophyllotoxin acetate (PA) as an anti-cancer drug candidate regulates various malignancy traits of non-small cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1241.