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Selective sensitivity to radiation of cerebral glioblastomas harboring p53 mutations
M Tada1, R Matsumoto, R D Iggo
1Laboratory for Molecular Brain Research, Hokkaido University School of Medicine, Sapporo, Japan. m_tada@med.hokudai.ac.jp
Abstract:
Recent studies suggest that a balance may exist between the cell cycle arrest and apoptosis-inducing functions of the p53 tumor suppressor gene. Adenoviral p21 transduction attenuates apoptosis, whereas deletion of the p21 gene promotes it, and p21-null xenografts respond better than isogenic p21-wild type tumors to irradiation. Hence, the role of p53 in dictating the clinical response to radiotherapy and chemotherapy may be more complex than previously thought. We have analyzed survival and radiation response (regrowth-free period) of 42 patients with glioblastomas whose p53 status was determined by a sensitive yeast functional assay. Multivariate analysis revealed that p53 mutation is associated with longer survival (P < 0.02). Among 36 radiation-treated patients, the regrowth-free period after treatment was significantly longer for tumors with p53 mutations (P < 0.0001), and p53 mutation was the sole independent factor predictive of radiotherapeutic response (P < 0.01). Survival time after regrowth was independent of p53 status, suggesting that the difference in survival was related to the treatment rather than to the intrinsic aggressiveness of the tumor. Thus, in this Northern Japanese population, p53 mutation is a marker for better radiation response in glioblastomas, and this results in significantly longer survival.
Insights
Glioblastoma patients with p53 mutations showed a better response to radiation therapy, leading to longer survival. This suggests p53 mutation status is a key indicator for predicting radiotherapy outcomes in glioblastoma patients.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- The p53 tumor suppressor gene plays a complex role in cell cycle arrest and apoptosis.
- The p53 gene's influence on treatment response, particularly radiotherapy and chemotherapy, is not fully understood.
- Previous research indicates p21, a gene regulated by p53, affects apoptosis and tumor response to irradiation.
Purpose of the Study:
- To investigate the association between p53 mutation status and patient survival in glioblastoma.
- To determine if p53 mutation status predicts response to radiation therapy in glioblastoma patients.
- To analyze the impact of p53 status on survival and radiation response in a Northern Japanese population.
Main Methods:
- Analysis of survival and radiation response (regrowth-free period) in 42 glioblastoma patients.
- Determination of p53 status using a sensitive yeast functional assay.
- Multivariate analysis to identify independent predictors of survival and treatment response.
Main Results:
- p53 mutation was significantly associated with longer overall survival (P < 0.02).
- Among radiation-treated patients, p53 mutations correlated with a significantly longer regrowth-free period (P < 0.0001).
- p53 mutation was identified as the sole independent factor predicting a better response to radiotherapy (P < 0.01).
Conclusions:
- In this cohort, p53 mutation serves as a marker for improved radiation response in glioblastomas.
- The observed differences in survival are linked to treatment efficacy rather than intrinsic tumor aggressiveness.
- p53 mutation status is a significant prognostic factor for glioblastoma patients undergoing radiotherapy.