[Hormonal control of zinc uptake in tumor cells]

Zinc is essential for the proliferation of tumor cells. It is suggested that tumor cell growth is inhibited by zinc deficiency in Yoshida sarcoma-bearing rats fed on a zinc-deficient diet. Clinically applicable methods for inducing a zinc-deficient condition in tumor cells were investigated for the therapeutic application of the above phenomenon. As one of these methods, the administration of progesterone to tumor-bearing rats was tried experimentally, and the changes in the zinc content of the tumor tissue and tumor growth were studied and compared with those of tumors in a control group. Progesterone is a competitive inhibitor of glucocorticoid which stimulates zinc uptake by tumor cells. In Yoshida sarcoma-or AH 109A-bearing rats, a tendency of reduction in zinc content in the tumor tissue and inhibition of the tumor growth in the progesterone-administered group was observed in comparison with the control group, although this was not very significant.