| ObjectiveBreast cancer is the most commonly malignancy cancer in women and is the first leading cause of cancer-related death in China. Current therapies, such as surgery, chemotherapy and radiation therapy are of limited efficacy, especially in advanced disease, and metastatic disease remains incurable. Therefore, there is an urgent need to discover novel and effective chemopreventive and therapeutic approaches for breast cancer. TNF-related apoptosis-inducing ligand (TRAIL) is the most recently identified member of the tumor necrosis factor (TNF) superfamily capable of inducing apoptosis in various cancer cell types. TRAIL binds to two distinct death receptors:DR4 and DR5, to trigger apoptotic signals. TRAIL can kill tumor cells effectively without being lethal to normal cells. In our study, we combined TRAIL with natural compound, resveratrol, to examine the effects on proliferation and apoptosis in human breast cancer cell line MDA-MB-231 and explored the mechanism to discover a new approaches.MethodsHuman breast cancer cell line MDA-MB-231 were cultured in vitro treated with vary concentration of TRAIL and/or resveratrol. The proliferation were detected by MTT assay and colony formation in soft agar. DAPI staining and flow cytometry were used to analyze cell apoptosis. The expression of DR4 and DR5 on the surface of MDA-MB-231 cell were examined by flow cytometry.Results1.TRAIL and resveratrol synergistically inhibited cell proliferation in MDA-MB-231 cellsAfter treatment with 25,50,100 and 200μmol/L resveratrol for 12h, the inhibitary rate of MDA-MB-231 cells was 24.22%±1.66%,30.79%±1.6%,45.72%±1.25% and 53.31%±1.94%(P＜0.01). After treatment with 50,100 and 200 ng/ml TRAIL for 12h, the inhibitary rate of MDA-MB-231 cells was 13.69%±3.24%,45.99%±1.37% and 61.29%±3.41%(P＜0.01). After treatment with 50 ng/ml TRAIL combined with 50 or 100μmol/L resveratrol for 12h, the inhibitary rate was 62.43%±2.07% and 87.32%±1.44%, respectively, which was significant differences compared with TRAIL or resveratrol alone (P＜0.01)After treatement with 50ng/ml TRAIL combined with 50 or 100μmol/L resveratrol for 14d, the colony forming rate in sofe agar were 2.49%±0.08% and 1.38%±0.07% and difference was significant compered with that of group treated with TRAIL or resveratrol alone (P＜0.01)2. TRAIL and resveratrol synergistically induced apoptosis in MDA-MB-231 cellsBy DAPI staining, TRAIL combined with resveratrol induces a significant chromatin condensation, margination, and nuclear fragmentation pattern as compared with control group or TRAIL/resveratrol alone.After trearment with 50,100 and 200μmol/L resveratrol for 12h, the apoptosis rates of MDA-MB-231 cells were 28.80%±1.34%,38.78%±1.19% and 58.96%±1.26% (P＜0.01). After treatment with 50,100 and 200ng/ml TRAIL for 12h, the apoptosis rates were 15.94%±0.34%,42.62%±0.99% and 76.30%±2.80%(P＜0.01). After treatment with 50ng/ml TRAIL combined with 50 or 100μmol/L resveratrol for 12h, the apotosis rates were 53.59%±1.44% and 73.72%±1.96%(P＜0.01)3. Resveratrol upregulated expression of DR4 and DR5 on cell surfaceThe fluorescence index of DR4 and DR5 on the surface of MDA-MB-231 cells were 1.52±0.04 and 1.61±0.13. After treatment with 50,100 and 200μmol/L resveratrol, the fluorescence index of DR4 were 1.80±0.07,2.11±0.14 and 2.59±0.16 (P＜0.01) whill the fluorescence index of DR5 were 2.16±0.08,2.92±0.25 and 3.90±0.06 (P＜0.01)Conclusion1. TRAIL and resveratrol could inhibite proliferation and induce apoptosis in human breast cancer cell line MDA-MB-231 in concentration-dependet manner alone.2. The synergism could be seen in inhibiting proliferation and inducing apoptosis by TRAIL combined with resvetatrol in concentration-dependet manner. 3. One of the mechanism of synergetic effect may be related to the up-regulation of expression of DR4 and DR5 on the cell surface.
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