Calcitriol Revises Aromatase Gene Expression in Ehrlich Solid Tumor Bearing Mice Exposed to Low Dose Gamma Radiation

Abstract

Background: Dysregulation of aromatase expression had been monitored in many types of cancer. Our study aimed to evaluate the possible role of calcitriol (Cal; Vit D3-OH) or/and low dose of gamma radiation in regulation of aromatase gene expression and the regression of tumor proliferation in murine model (EST; Ehrlich solid tumor bearing mice). Methods: Mice with ≈1 cm3 EST were received (i.p. injection) day after day repeated doses of Calcitriol (Cal) (0.05µg/mouse) for 14day or/and exposed to 0.5 Gy gamma radiation (low dose) delivered as one shot at dose rate 0.48 Gy/min. Results: Our results demonstrated that, mRNA expression of aromatase, levels of cyclooxygenase (COX2) and prostaglandin (PGE2) in addition to volume of the tumor are significantly decreased while caspase 3 level is significantly increased in EST mice treated with Cal or/and exposed to 0.5 Gy gamma ray compared to untreated EST bearing mice. However, the most pronounced improvements in all of the measured parameters were obviously indicated in EST mice group treated with Cal and exposed to gamma radiation. This was accomplished by suppression of inflammatory markers which cause down regulation in aromatase mRNA expression as well as augmenting apoptosis by inducing Caspase3 concentration. Conclusion: It could be concluded that the exposure to low dose gamma radiation potentiate the action of Calcitriol against tumor growth in the subjected murine model which represent a prospective policy for the management of solid tumor and decreasing the possibilities of tumor drug resistance.