Hormone-dependent growth of a rat chondrosarcoma in vivo

The importance of various hormonal factors in the growth of a transplantable chondrosarcoma has been studied in vivo. Tumor growth was reduced by 95% in adrenalectomized or hypophysectomized rats as compared to normal animals. The number of tumors developing in either adrenalectomized or hypophysectomized rats was reduced more in male than in female rats. However, ovariectomy or orchiectomy did not alter the growth of the tumor. The inhibition of tumor growth in adrenalectomized and hypophysectomized animals was only observed after the first 10 days following inoculation. Cortisone (4-pregnen-17 alpha,21-diol-3,11,20-trione) administration fully restored tumor growth in adrenalectomized animals while adrenocorticotropic hormone or growth hormone were only partially effective in supporting tumor growth in hypophysectomized animals. High-affinity glucocorticoid receptors (7 to 10S) were present in the cytosls prepared from the tumor cells and were found to be increased in tumors from adrenalectomized animals. These results indicate that the growth of this chondrosarcoma is strongly dependent upon endocrine factors of adrenal and pituitary origin.