Abstract 1658: Cell death and growth arrest pathways mediating the actions of stilbene 5c in HCT-116 colon cancer cells and B16F10 melanoma cells.

Abstract

Abstract The stilbene derivative, cis-3, 4’, 5-trimethoxy-3’-aminostilbene (stilbene 5c), is a potentially potent antitumor agent that acts via binding to the colchicine-binding pocket in microtubules. Earlier studies have shown that stilbene 5c induces cell death in ovarian cancer cells and leukemic cells (Cao TM et al. Am J Hematol. 2008;83:390-7; Durrant D et al. Gynecol Oncol. 2008; 110:110-7).). The present study was designed to investigate the effectiveness of this microtubule poison against the HCT-116 human colon cancer cell line as well as B16F10 melanoma cells and its mechanisms of action. Time course studies demonstrated that stilbene 5c produces a decrease in cell viability in both cell lines. The capacity of the cells to proliferate was not restored upon removal of the drug after 5 days of exposure. Consistent with the results of the time course studies, β-galactosidase staining indicated that treatment with stilbene 5c also promotes senescence. In addition to senescence, HCT-116 cells and B16F10 melanoma cells treated with stilbene 5c displayed formation of autophagic vesicles by acridine orange staining, which was supported by fluorescence-activated cell sorting (FACS). Further evidence of autophagy was derived from treatment of HCT116 cells expressing an RFP-LC3 construct with stilbene 5c, in which LC3 puncta formation increased in a time-dependent manner. DAPI staining, TUNEL, and Annexin 5 staining indicated that apoptosis is also occurring in stilbene 5c-treated HCT-116 cells. Cell cycle analysis of HCT116 cells demonstrated growth arrest at both G1 and G2/M, and an increase in the subG1 population at days 3 and 5, which correspond to senescence and apoptosis respectively. Interestingly, DAPI and Hoechst staining of HCT116 cells revealed morphological changes in the cell nuclei (binucleated and micronucleated cells), which suggest that mitotic catastrophe may also serve as a mode of cell death after treatment with stilbene 5c. Our studies also indicated that stilbene 5c works in a p53-independent manner. p53-null HCT116 cells demonstrated similar sensitivity to stilbene as p53-wild type HCT116 cells. Consistent with previous studies in other experimental cancer models, this work indicates that stilbene 5c could potentially be effective against melanoma and colon cancer through the promotion of multiple modes of cell death. Citation Format: Moureq R. Alotaibi. Cell death and growth arrest pathways mediating the actions of stilbene 5c in HCT-116 colon cancer cells and B16F10 melanoma cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1658. doi:10.1158/1538-7445.AM2013-1658