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Functional p53 mutation as a molecular determinant of paclitaxel and gemcitabine susceptibility in human bladder
S J Kielb1, N L Shah, M A Rubin
1Departments of Urology and Pathology, Prostate Cancer and Urological Oncology Program, University of Michigan, Ann Arbor, Michigan, USA.
Purpose:
Paclitaxel and gemcitabine are promising new agents for treatment of human bladder cancer. We determine how the presence or absence of p53 function impacts the cytotoxic effects of these chemotherapeutic agents in human bladder cancer.
Materials And Methods:
The J82 human bladder cancer (TCC) cell line was transfected with a temperature sensitive p53 (tsp53) mutant that functions as mutated p53 at 37C but functions as wild-type (normal) p53 at 32C. Susceptibility of these inducible p53 TCC cells to paclitaxel and gemcitabine induced cytotoxicity was evaluated and kill significance determined between sub-lethal and lethal doses.
Results:
Significant paclitaxel dose dependent cytotoxicity was observed in J82 TCC cells lacking normal p53 and tsp53 transfected cells at 37C, which was the mutant p53 temperature in transfectants between maximal and minimal kill concentrations for either (p <0.001). Likewise, significant cytotoxicity was observed in parental J82 TCC at 32C (p <0.001), while restoration of p53 function in tsp53 transfected cells on shift to 32C abrogated significant dose dependent cytotoxicity. Gemcitabine caused significant cell death in the cell lines incubated at either temperature and, thus, was equally effective regardless of cellular p53 function (p <0.001, respectively).
Conclusions:
Paclitaxel requires functionally mutated p53 to induce cell death in human bladder cells, indicating that it may be more effective against TCC with p53 mutations than against TCC, which lacks p53 abnormalities, while gemcitabine is effective regardless of p53 function. These findings provide a rationale for selecting chemotherapy based on the p53 status of individual bladder cancers.
Insights
Paclitaxel effectiveness in bladder cancer depends on p53 mutation status, while gemcitabine works regardless of p53 function. This guides personalized chemotherapy selection for TCC patients.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Therapeutics
Background:
- Human bladder cancer (TCC) treatment involves chemotherapy.
- The role of p53 tumor suppressor gene function in TCC response to chemotherapy is not fully understood.
- Paclitaxel and gemcitabine are novel chemotherapeutic agents for TCC.
Purpose of the Study:
- To investigate the impact of p53 functional status on the efficacy of paclitaxel and gemcitabine in human bladder cancer cells.
- To determine if p53 mutation or wild-type status influences chemotherapy-induced cytotoxicity.
Main Methods:
- A J82 human bladder cancer cell line was engineered to inducibly express functional or mutated p53.
- Cells were treated with varying doses of paclitaxel and gemcitabine at temperatures that either activated (wild-type p53) or deactivated (mutant p53) the p53 protein.
- Cytotoxicity was quantified and compared between conditions with different p53 functional states.
Main Results:
- Paclitaxel demonstrated significant dose-dependent cytotoxicity in cells with non-functional p53 (mutant p53) but not in cells with restored wild-type p53 function.
- Gemcitabine induced significant cell death irrespective of the p53 functional status of the bladder cancer cells.
- p53 status significantly influenced paclitaxel's cytotoxic effect, but not gemcitabine's.
Conclusions:
- Paclitaxel efficacy in TCC is dependent on the presence of functionally mutated p53.
- Gemcitabine exhibits consistent effectiveness against TCC, regardless of p53 mutation status.
- Bladder cancer chemotherapy selection can be guided by individual tumor p53 status for optimized treatment strategies.