DETECTION OF GASTRIN MESSENGER-RNA IN FRESH HUMAN COLONIC CARCINOMAS BY REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION

To investigate the hypothesis that gastrin might be synthesized by tum our tissues in cancer of the colon, samples from six human colon tumou rs, one hepatic metastasis, four normal colonic mucosal samples and tw o antral and one fundic gastric mucosal samples from nine patients wer e analysed to determine whether gastrin mRNA was present. RNA was extr acted from surgical specimens by ultracentrifugation on a CsCl cushion , purified using the guanidinium thiocyanate method, reverse-transcrib ed and amplified by polymerase chain reaction. Gastrin mRNA was detect ed in each colonic carcinoma sample (including the hepatic metastasis) , while no such signal was observed in normal colon biopsies. Positive and negative controls (gastric antrum and fundus respectively) gave t he expected results. In each of the positive samples, the chemilumines cent revelation of amplified products after Southern blotting correspo nded to gastrin mRNA without the intron. These findings demonstrate th e ability of primary and metastatic human colonic tumours to produce g astrin mRNA. Since malignant cell lines have been reported to produce gastrin peptide, and since gastrin receptors were present in some case s, our results support the idea that gastrin may be involved in an aut ocrine mechanism.