Abstract 876: Molecular mechanisms of paclitaxel-resistance and resveratrol sensitivity in MDA-MB-231 breast cancer cells.

Treatment of drug-resistant cancer cells remains a difficult problem in cancer therapy because most resistant cells can pump out drugs or upregulate other survival pathways to bypass a targeted therapy. To study cancers that are resistant to the common cancer drug, paclitaxel, a novel paclitaxel-resistant cell line was generated from the breast cancer cell line MDA-MB-231. A “spiking” method of paclitaxel treatment was used to select for a population of cells that are resistant to the drug. This method mimics the development of resistance in recurrent tumors in patients. The IC50 of paclitaxel in these cells was 75 μM compared to the 0.037 μM IC50 of the parent cell line, a 2000-fold increase in resistance. In this very heterogeneous population, the mechanism of resistance was not due to increased protein levels of the efflux protein, p-glycoprotein, as quantitated by western blot analysis. To better study these cells, the paclitaxel-resistant cell line was cloned using a limiting dilution method to provide more homogeneous populations of resistant cells. The 29 clones obtained exhibited a paclitaxel IC50 range of 8 μM to 78 μM which was equivalent to a 200- to 2000-fold increase in resistance compared to the parent line. It has been suggested that the polyphenol natural compound, resveratrol, which has been shown to inhibit cell growth of multiple cancer types, may be useful as a combination anti-cancer treatment or novel therapeutic for drug-resistant cancer cells. There was no significant difference among the 72 hour IC50 of resveratrol in the parent line, the heterogeneous resistant line, the least paclitaxel-resistant clone or the most paclitaxel-resistant clone. We observed that treatment with 10-100 μM concentrations of resveratrol in all cell lines showed a reduction in cell proliferation and increased apoptosis within 72 hours (p Citation Format: Alyssa A. Sprouse, Brittney-Shea Herbert. Molecular mechanisms of paclitaxel-resistance and resveratrol sensitivity in MDA-MB-231 breast cancer 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 876. doi:10.1158/1538-7445.AM2013-876