Epidermal chalone and mitotic control in the Vx2 epidermal tumour.

Abstract

In a number of tissues It has been found that mitotic activity is controlled by specific mitotic inhibitors, called chalones. It is now shown that in four malignant tumours (epidermal carcinoma, granu-locytic leukaemia, melanotic and amelanotic melanomata) the chalones of the tissues of origin are still synthesized, although the chalone content is abnormally low, and that in all cases the tumours are still capable of responding by mitotic inhibition when the chalone content is artificially raised. It is also shown that when extracts of normal skin or of melanomata (both of which contain the melanocyte chalone) are injected for 5 days into mice or hamsters bearing large malignant melanomata, rapid tumour regression occurs and in some cases leads to a complete cure.