Pifithrin-α as a potential cytoprotective agent in radiotherapy: protection of normal tissue without decreasing therapeutic efficacy in glioma cells.

Activation of p53 has been causally linked to normal tissue damage after irradiation. Pifithrin-α (PFT-α), a specific inhibitor of p53, has been suggested as a combinatory agent in the treatment of p53-deficient tumors in which inhibition of p53 would not compromise therapeutic efficacy but would decrease p53-mediated side effects in normal tissue. We tested this concept for radiotherapy of p53-deficient and -proficient glioma.

Caffeine confers radiosensitization of PTEN-deficient malignant glioma cells by enhancing ionizing radiation-induced G1 arrest and negatively regulating Akt phosphorylation.

PTEN mutations are frequently found in malignant glioma and can result in activated phosphatidylinositol-3-kinase/Akt survival signaling associated with resistance to radiotherapy. Strategies to interfere with aberrant PI3K/Akt activity are therefore being developed to improve the therapeutic efficacy of radiotherapy in patients with malignant glioma. The methylxanthine caffeine has been described as a PI3K inhibitor and is also known to sensitize cells to ionizing radiation.