Abstract 479: The effects of sarcophine-diol (SD) on melanoma B16F10 cell line

Abstract

Abstract Sarcophine diol (SD) is a non-toxic semi-synthetic derivative of sarcophine, a marine natural product. Previously, we studied the chemopreventive effects of SD on non-melanoma tumor development using both animal and cellular models. In this current study, we used the mouse melanoma B16F10 cell line to investigate the possible effects of SD on melanoma cell development. We found that SD at a 250 µM concentrations inhibits cell duplication. Melanoma cells treated with SD do not form the contractile ring, a multi-protein complex involved in cell division. As a result of cytoskeleton modification, cells treated with SD do not show the ability to carry out de novo synthesis of DNA, and their DNA show a high degree of fragmentation compared to untreated controls. To explore the molecular mechanism(s) involved in the disassembly of the contractile machinery, our studies show that SD treatment inhibits cell membrane permeability for small molecular mass compounds (e.g. ethidium bromide which is used as an indicator for cell permeability to Ca2+ ions). These findings are consistent with the observation that SD increases cleavage of phospholipase A2 (PLA2), resulting in low PLA2 enzymatic activity. These findings are also consistent with the observation that SD, in a time- and concentration-dependent manner, inhibits the expression level of the cyclooxygenase-2 (Cox-2). As a result of the decline in membrane permeability in SD treated cells and the negative effect of SD on the protein level of phospholipase C (PLC), which both affect the activity of contractile machinery, the non-dividing cells undergo apoptosis. The latter notion is supported by findings that SD inhibits the expression of STAT-3 (signal transducer and activator of transcription protein), and cyclin D1 (an activator of cyclin-dependent kinase 4, Cdk4). SD treatment also enhances the cellular level of the tumor suppressing protein 53 (p53) and stimulates cleavage of the nuclear poly(ADP-ribose) polymerase (cleaved-PARP). SD also enhances the cellular level of cleaved-Caspase-3, -8, -9 and stimulates enzymatic activities of Caspase-3, -8 and -9. All these findings, in addition to inhibition of cell viability, suggest that SD most likely inhibits melanoma cell growth by arresting the cell-division cycle in a Go quiescent phase and simultaneously activates apoptosis via extrinsic and intrinsic pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 479. doi:1538-7445.AM2012-479