Somatostatin analogs show in vitro antiproliferative activity in a subset of human medullary thyroid carcinomas (MTC), Italian researchers have found.
Building on previous research in a human MTC cell line, the team from the University of Ferrara evaluated the effect of somatostatin analogs in cell cultures from 18 patients with MTC.
The samples included both thyroid and metastatic lymph node tissue, and were analyzed for somatostatin receptor subtype expression, as well as calcitonin and chromogranin A secretion. The cultures were then developed and tested with somatostatin analogs that interact with receptor subtypes 1, 2, and 5.
Results, published in the Journal of Clinical Endocrinology and Metabolism, showed that MTC tumor samples could be divided according to whether or not calcitonin secretion was inhibited by the clinically available somatostatin analog lanreotide.
In the "responder" group, calcitonin secretion was reduced by compounds interacting with somatostatin receptor subtypes 1, 2, and 5, but cell viability was unaffected.
By contrast, in the "non-responder" samples, calcitonin secretion was reduced by the somatostatin receptor subtype 1-selective agonist, while cell viability was inhibited by subtype 2-selective agonists.
The authors say that their findings could explain the "relative failure" of clinically available somatostatin analogs in controlling MTC growth, and underscore the importance of studying primary cultures from human tissues.
They conclude: "Our data suggest that somatostatin analogs might be useful in medical therapy of MTC, since they could have antiproliferative effects despite the lack of antisecretory activity, and vice versa."