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BAD partly reverses paclitaxel resistance in human ovarian cancer cells
T Strobel1, Y T Tai, S Korsmeyer
1Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA.
Abstract:
Although paclitaxel is an important chemotherapy agent for the treatment of patients with epithelial ovarian cancer, its utility is significantly limited by the frequent development of drug resistance. Recent evidence suggests that resistance to chemotherapy may be partly related to defects in the apoptotic pathway. In this study we have investigated whether enhancement of apoptotic pathway function through stable expression of the BAD protein is capable of sensitizing human epithelial ovarian cancer cells to the effects of chemotherapy. Expression of HA-BAD in six separate clonal transfectants from two different ovarian cancer cell lines was found to significantly enhance the cytotoxic effects of paclitaxel, vincristine, and, to a lesser extent, etoposide. Enhancement of paclitaxel-induced apoptosis in HA-BAD-expressing clones was demonstrated by trypan blue exclusion, clonogenic cell assay, and flow cytometric evaluation. Importantly, this effect was associated with binding of HA-BAD to BCL-xL and concomitant disruption of BAX:BCL-xL interaction. Taken together, these data suggest that the development of small molecules which mimic the effects of BAD may represent a new class of drugs capable of preventing or reversing resistance to chemotherapy agents such as paclitaxel.
Insights
Enhancing the apoptotic pathway by expressing the BAD protein can overcome chemotherapy resistance in ovarian cancer. This approach sensitizes cancer cells to drugs like paclitaxel, offering new therapeutic strategies.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Paclitaxel is a key chemotherapy for epithelial ovarian cancer but faces significant drug resistance.
- Chemotherapy resistance is often linked to defects in the programmed cell death (apoptosis) pathway.
Purpose of the Study:
- To investigate if enhancing apoptosis by stably expressing the BAD protein can sensitize human epithelial ovarian cancer cells to chemotherapy.
Main Methods:
- Stable expression of the HA-BAD protein in two ovarian cancer cell lines.
- Assessing the cytotoxic effects of paclitaxel, vincristine, and etoposide on HA-BAD-expressing cells.
- Evaluating paclitaxel-induced apoptosis using trypan blue exclusion, clonogenic assays, and flow cytometry.
- Analyzing the interaction of HA-BAD with BCL-xL and its effect on BAX:BCL-xL binding.
Main Results:
- Stable expression of HA-BAD significantly enhanced the cytotoxic effects of paclitaxel and vincristine.
- HA-BAD expression also increased sensitivity to etoposide, though to a lesser extent.
- Paclitaxel-induced apoptosis was significantly enhanced in HA-BAD-expressing clones.
- This enhancement correlated with HA-BAD binding to BCL-xL and disruption of BAX:BCL-xL interactions.
Conclusions:
- Enhancing apoptotic pathway function via BAD protein expression can overcome chemotherapy resistance in ovarian cancer.
- Targeting BAD-mediated apoptosis may offer novel therapeutic strategies to prevent or reverse resistance to agents like paclitaxel.