Peculiarities of hormonal regulation of adenylate cyclase and lipid composition in colonic and rectal tumors.

Peculiarities in hormonal regulation of adenylate cyclase (AC) were studied in large bowel tumors to establish criteria of their hormonal dependence. The investigation showed a diminished basal activity of AC matched by decreased response to sodium fluoride, glucagon, and vasoactive intestinal peptide (VIP) in tumors as compared with normal intestinal mucosa. Some cases revealed an increased response of AC to a nonspecific ("inappropriate") stimulator--calcitonin. This was rather typical of colonic tumors while a diminished response to specific ("appropriate") stimulation by VIP and glucagon was more frequent in rectal cancer. The results showed a relationship between hormonal regulation of AC activity and lipid composition of tumor tissue, thus suggesting the possibility of influencing the hormone dependence of intestinal tumors by drugs used to eliminate disturbance of fat-carbohydrate metabolism.