Abstract
Cervical dysplastic lesions called cervical intraepithelial neoplasias (CINs) need be treated to prevent cervical cancer. Currently available surgical procedures are effective, but the development of noninvasive treatment is warranted. In human papillomavirus transgenic mice engineered to express human papillomavirus type 16 E6 and E7, short-term treatment with 17β-estradiol induces CINs that progress to cervical cancer if the treatment is continued. In the present study, this mouse model was used to determine whether medroxyprogesterone acetate (MPA), a progestin drug, is chemopreventive. Human papillomavirus transgenic mice bearing CIN lesions were treated with MPA plus 17β-estradiol. Unlike control mice treated with 17β-estradiol alone, cervical cancer was absent in the MPA-treated mice. This observation suggests that MPA prevented CIN from progressing to invasive cancer. MPA was associated with inhibited cell proliferation and the promotion of apoptosis in CIN lesions. Confirming the role of the progesterone receptor, the preventive effect of MPA was absent in human papillomavirus transgenic mice in which the expression of progesterone receptor was genetically ablated. These results suggest that MPA is efficient in treating progesterone receptor-positive CIN lesions. These findings provide the basis for a biomarker-driven clinical trial of the secondary prevention of cervical cancer.