Hormonal regulation of epidermal tumor development

The effects of hormones and hormone-like substances such as thyroxine, estradiol, hydrocortisone, calcitonin, prostaglandins (F2a, A2) or hormone deficiency (hypophysectomy, gonadectomy) on the development of carcinomas in mice and rats induced by 3-methylcholanthrene were investigated. Thyroxine, PGF2a, calcitonin, and estradiol markedly enhanced the development of squamous cell carcinomas and basal cell carcinomas; an inhibition occurred following hydrocortisone, hypophysectomy, and gonadectomy. DNA labeling using [3H]-thymidine and radioautography revealed that DNA synthesis in neoplastic cells is also markedly influenced by the same hormones. Tumor histology and ultrastructure are profoundly affected and an increase of epithelial pearls, hyperchromatic basophilic cells, tonofilaments, polyribosomes, and lysosomes is observed following thyroxine and PGF2a. An increase of keratinization and intramitochondrial granules occurred with estradiol and increased sclerosis followed calcitonin. A marked reduction of cell organelles occurred after hydrocortisone, hypophysectomy, and gonadectomy. Scanning electron microscopy shows salient changes in tumor cytoarchitecture and cell surfaces (blebs, ruffles). These findings demonstrate that hormones can change the development of carcinomas, DNA synthesis as well as their cellular differentiation and consequently may be important modulators of epidermal carcinogenesis.