Bcl-2, bax, and p53 immunohistochemical alternations as predictive markers for radiotherapy in patients with localized prostate cancer.

S Kariya, MD, PhD^a, Y Ogawa, MD, PhD^a, A Nishioka, MD, PhD^a, M Furihata, MD, PhD^b, K Kasahara, MD^c, K Inoue, MD, PhD^c, T Shuin, MD, PhD^c, S Yoshida, MD, PhD^a

AIM: We determined the level of the bcl-2, bax, and p53 expressions in the prostate cancer cells before and during radiation treatment in addition to investigating if there is a correlation between those alternations and the clinical response to radiotherapy in patients with localized prostate cancer. METHODS: Prostate tissues from 14 patients with localized prostate cancer were obtained before and after high dose rate (HDR) interstitial brachytherapy with three fractions of 6 Gy each followed by external beam irradiation of 40-45 Gy for the prostate or pelvis. Immunohistochemical analysis was performed on frozen prostate tissue sections to determine the level of expression of bcl-2, bax, and wild and mutant types of p53 in prostate cancer cells. RESULTS: In 12 of the 14 total patients, the ratio of bcl-2 and bax expression during radiotherapy decreased compared to that before radiotherapy. The level of expression of either type of p53 did not change. In these patients, the level of PSA (prostate specific antigen) decreased smoothly after radiotherapy. In the remaining 2 patients, however, the ratio of bcl-2 and bax expression did not change, while the level of expression of the mutant type of p53 elevated during radiotherapy. In 1 of these 2 patients, the level of PSA stopped to decrease at a level of about 1 ng/ml. CONCLUSIONS: We found that the level of expression of bcl-2, bax, and p53 changed during the early stage of radiotherapy. Those alternations may become predictive markers of therapeutic response after radiotherapy of local prostate cancer.

KEY WORDS: Prostate cancer, Predictive marker, Bcl-2, Bax, p53, Radiation.

For more information, contact kariyas@kochi-ms.ac.jp

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Predictive Markers.

http://www.cancerprev.org/Journal/Issues/26/101/1196/4460