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Norcantharidin-induced post-G(2)/M apoptosis is dependent on wild-type p53 gene
1Department of Dentistry, National Taiwan University, Taipei, Taiwan, Republic of China.
Abstract:
Norcantharidin (NCTD), a synthetic analogue of phosphatase type 2A inhibitors, cantharidin, was shown to have limited effects in treating human and animal tumors. The tumor cell killing mechanisms by norcantharidin, however, remain unclear. In this report, we wished to investigate the mechanisms of norcantharidin-mediated cytotoxicity. Effort was made to investigate whether norcantharidin exerted its cytotoxicity through a p53-dependent or -independent mechanism. RT-2 (wtp53) and U251 (mutant p53) glioblastoma cell lines were exposed to norcantharidin at different dosages. Time-course fluorescent-activated cell sorting (FACS) analysis showed that high doses of norcantharidin arrested the cells at the G(2)/M phase and subsequent post-G(2)/M apoptosis in RT-2 cell line. In comparison, the U251 cell line was found resistant to norcantharidin-induced cytotoxicity. Restoring wild-type p53 gene function in the U251 cell line after adenoviral infections induced tumor cell cytotoxicity after exposure to norcantharidin. These results showed that norcantharidin kills tumor cells efficiently corresponding to their endogenous p53 gene status. The results also showed the feasibility of using adenoviral p53 gene therapy to enhance chemosensitivity of tumor cells to norcantharidin.
Insights
Norcantharidin (NCTD) demonstrates tumor cell cytotoxicity dependent on p53 gene status. Adenoviral p53 gene therapy can enhance NCTD chemosensitivity in resistant tumors.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Norcantharidin (NCTD), a cantharidin analogue, exhibits limited efficacy in tumor treatment.
- The precise mechanisms of NCTD-induced tumor cell death remain largely unelucidated.
- Investigating the role of p53 in NCTD cytotoxicity is crucial for understanding its therapeutic potential.
Purpose of the Study:
- To elucidate the mechanisms underlying norcantharidin-mediated cytotoxicity.
- To determine if NCTD exerts its cytotoxic effects via a p53-dependent or -independent pathway.
- To explore the potential of combining NCTD with p53 gene therapy for enhanced anti-tumor activity.
Main Methods:
- Utilized RT-2 (wild-type p53) and U251 (mutant p53) glioblastoma cell lines.
- Administered varying dosages of norcantharidin to cell lines.
- Performed time-course fluorescent-activated cell sorting (FACS) analysis.
- Employed adenoviral vectors to restore wild-type p53 function in U251 cells.
Main Results:
- High-dose NCTD induced G(2)/M phase arrest and apoptosis in RT-2 cells.
- U251 cells exhibited resistance to NCTD-induced cytotoxicity.
- Restoration of wild-type p53 in U251 cells sensitized them to NCTD, leading to tumor cell death.
- NCTD efficacy correlates with endogenous p53 gene status.
Conclusions:
- Norcantharidin-mediated tumor cell killing is dependent on the endogenous p53 gene status.
- Adenoviral-mediated p53 gene delivery can enhance the chemosensitivity of tumor cells to norcantharidin.
- This study highlights a potential strategy for improving NCTD-based cancer therapy.