Bax protein expression correlates with radiation-induced apoptosis in radiation therapy for cervical carcinoma.
BACKGROUND
Bax protein serves as a positive regulator of apoptosis by forming heterodimers with bcl-2 protein, thereby promoting cell survival. It is unclear whether the regulation of apoptosis reported in many studies is applicable to the apoptotic phenomenon observed in conventional fractionated radiation therapy for cervical carcinoma.


METHODS
The authors assessed the relation between apoptosis and the expression of Bax and bcl-2 protein in fractionated radiation therapy for cervical carcinoma by using in situ nick end labeling (ISEL) and immunohistochemical methods.


RESULTS
Specimens were excised from the cervical tumors of 20 patients before and after administration of a total irradiation dose of 9 gray (Gy). The apoptotic cell index (AI) in tumor cells was 0.22% before irradiation and 1.20% after the administration of the 9 Gy, which represented a significant increase (P=0.0004). The positive rate of Bax protein increased from 15% (in 3 of 20 patients) before irradiation to 60% (in 12 of 20 patients) after the 9 Gy was administered, a statistically significant change (P=0.0126). In addition, there was a significant correlation between Bax protein expression and apoptosis positivity after the 9 Gy was administered (P=0.018).


CONCLUSIONS
These results suggest that Bax protein is associated with apoptosis induced by fractionated radiation therapy.
Ohno
T
T
Division of Radiation Medicine, National Institute of Radiological Sciences, Chiba, Japan.
Nakano
T
T
Niibe
Y
Y
Tsujii
H
H
Oka
K
K
D017209:Apoptosis / Q000528:radiation effects*; D005260:Female; D006801:Humans; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D002583:Uterine Cervical Neoplasms / Q000737:chemistry / Q000473:pathology / Q000532:radiotherapy*; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein