Resveratrol and Radiation: Cytotoxicity and Cell Cycle Analysis

Abstract

The primary purpose of our experiments was to determine if resveratrol, a polyphenolic compound found in different fruits, most notably the skins of red grapes, could enhance the killing of tumor cells treated with radiation. Using the melanoma‐derived MDA‐MB 435 cell line, cytotoxicity experiments were conducted to test the effects of these treatments both combined and individually on the cell line. Combination of both treatments exhibited additive effects on the amount of killing of these cells. To determine the mechanism by which this was occurring, analysis of the cell cycle was conducted using flow cytometry. Radiation (2Gy) and resveratrol (0.0135mg/ml) were shown to arrest the cells in the G2 and S phases of the cell cycle, respectively. Combination of these two treatments showed additive effects, arresting a greater percentage of cells in both the S and G2 phases of the cell cycle. A sub‐G­1 peak was also observed, suggesting some cells undergoing apoptosis. The Annexin Apoptosis Assay has shown conflicting resultssince cells treated with radiation and resveratrol have shown less apoptosis than cells treated with radiation alone. Further experiments using reverse transcriptase quantitative PCR were conducted to determine if select tumor suppressor (p53, Rb) and oncogenes (Myc and Bcl‐2) vary in levels among the treated cells. Upregulation of Bcl‐2, Rb1 and p53 was observed in cells treated with resveratrol alone and in cells treated with both resveratrol and radiation, perhaps protecting them from apoptosis. Our ongoing experiments will provide further insight to the mechanism by which cell death is occurring and explain the changes in the cell cycle.