Pretreatment of endometrial carcinoma cell lines with butyrate results in upregulation of Bax and correlates with potentiation of radiation induced cell kill.

BACKGROUND

Endometrial carcinoma is the most common gynecologic malignancy. Surgery has been the standard therapy for stage I and II endometrial carcinoma and radiation therapy either before or after surgery has been used to improve local control especially for high grade lesions. We have used Sodium Butyrate (BA) in order to examine whether endometrial carcinoma cells can be rendered more sensitive to radiation therapy.

METHODS

Endometrial carcinoma cells in culture were pretreated with sodium butyrate and then irradiated. Clonogenic survival assay was used to determine percentage of surviving cells. Changes in Bax and Bcl-2 protein levels were determined by Western blot analyses. Effect of Bcl-2 overexpression on induction of Bax in response to butyrate pretreatment was studied in cells transfected with Bcl-2.

RESULTS

A 24 h pretreatment of SKUT2 and Hec-1A cells with BA has an additive effect with radiation. Analysis of pro and anti-apoptotic protein levels revealed that the 24 h pretreatment with BA resulted in increased expression of the proapoptotic protein Bax which correlated with potentiation of radiation induced cell kill. Treatment of cells over expressing Bcl-2 with BA did not show induction of Bax suggesting that higher levels of Bcl-2 can block butyrate induced increase in levels of Bax.

CONCLUSIONS

Use of BA at lower than toxic doses to upregulate the proapoptotic potential of cancer cells may be useful in an adjuvant or neoadjuvant setting but its success may depend upon the intrinsic Bcl-2 levels in the tumor.