Poston GJ, Draviam EJ, Seitz PK, Rajaraman S, Alexander RW, Cooper CW, Townsend CM, Thompson JC. Expression of cholecystokinin forms by medullary thyroid cancer.
Int J Cancer 1991;
48:689-92. [PMID:
2071230 DOI:
10.1002/ijc.2910480510]
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Abstract
We have studied the production and release of cholecystokinin (CCK) forms by rat medullary thyroid cancer (MTC) in vivo. MTC cells were inoculated s.c. into 8 Wag-Rij rats. One month later, after i.v. injection of calcium plasma levels of CCK, calcitonin and tissue contents of gastrin and calcitonin were determined by radioimmunoassay (RIA), immunocytochemistry, and high-pressure liquid chromatography (HPLC). The tumors were passed 4 times to 8 rats in 1-month intervals fasting levels of CCK in control rats were unaffected by calcium stimulation, and in tumor-bearing rats, plasma CCK was elevated in 3 out of 4 passages, falling to normal levels at the end of passage 4. Hypercalcemia had no effect on plasma levels of CCK in tumor-bearing rats, but did stimulate the release of calcitonin in both control and some tumor-bearing rats in later passages. CCK-8 sulfate was found in all 4 tumor passages but not CCK-33/39. We conclude that rat MTC synthesizes and releases CCK-8, but unlike calcitonin, release of CCK appears unresponsive to calcium stimulation.
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