Browsing by Subject "drug-resistant cancer cells"

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    EFFECTS OF RESVERATROL ON PACLITAXEL-SENSITIVE AND –RESISTANT TRIPLE NEGATIVE BREAST CANCER CELLS
    (Office of the Vice Chancellor for Research, 2012-04-13) Sprouse, Alyssa A.; Herbert, Brittney-Shea
    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. The poly-phenol natural compound, resveratrol, has been shown to inhibit cell growth of multiple cancer types, but it is not cytotoxic to normal cells. However, the effects of resveratrol in triple negative breast cancer cells as well as cancers that are resistant to the common cancer drug, paclitaxel, are not well under-stood. In this study, the effects of resveratrol were investigated in the triple negative breast cancer cell line MDA-MB-231 as well as a novel paclitaxel-resistant MDA-MB-231 derived line generated in our laboratory. Both cell lines exhibited a reduction in cell proliferation after resveratrol treatment, with the paclitaxel-resistant cells to a greater extent. In addition, resveratrol decreased the ability of both cell lines to form colonies when plated at low density indicating reduced cell survival capacity. Resveratrol treatment also increased the amount of DNA fragmentation associated with cell death in both cell lines, again with the paclitaxel resistant cells being more sensitive. By protein expression analyses, we observed that in both the parental and resistant cell lines, resveratrol may be acting by through NAD-dependent deacetylase sirtuin (SIRT1) activity by decreasing the expression of the in-hibitor-of-apoptosis protein, survivin, as well as increasing the activator-of-cell death, caspase 7. These data suggest that resveratrol can inhibit prolif-eration and induce cell death in triple negative breast cancer cells, including paclitaxel-resistant cells. In addition, these results provide rationale for the use of resveratrol as an important starting point for the development of a novel anti-cancer agent for drug resistant, aggressive cancers as well as in combination with other anti-cancer drugs without significant toxicity to nor-mal cells.
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    Molecular Mechanisms of Paclitaxel Resistance and Resveratrol Sensitivity in MDA-MB-231 Breast Cancer Cells
    (Office of the Vice Chancellor for Research, 2013-04-05) Sprouse, Alyssa A.; Herbert, Brittney-Shea
    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. However, it is difficult to study such a heterogeneous population. 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. The parent line, the heterogeneous resistant line, the least paclitaxel-resistant clone and the most paclitaxelresistant clone were similarly sensitive to resveratrol treatment. 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<0.05), with the paclitaxel-resistant cells to a greater extent. In addition, resveratrol decreased the ability of the parent, heterogeneous resistant and the highest resistant clone cells to form colonies (an indication of reduced cell survival capacity). This resistant cell line and its clones provide a powerful tool to study paclitaxel-resistance in and therapeutics for breast cancer.