Influence of sexual hormones on solid tumor growth and ATP C+ cell replication

Solid tumors obtained by implanting ATP C+ cells subcutaneously into the back of BALB/cf/Had/Se substrain mice developed more rapidly in males than females. Experiments conducted on gonadectomized animals demonstrated that female gonads inhibit the development of this tumor. Studies on ATP C+ cells cultured in vitro with various doses of male and female hormones showed that mainly progesterone, but to a lesser extent also estradiol, significantly inhibit cell proliferation with respect to testosterone. The treatment of normal and gonadectomized animals with testosterone and progesterone confirms the results obtained in vitro. Analyses carried out on ATP C+ cells do not reveal presence of estradiol and progesterone receptors.