Expression of c-sis/platelet-derived growth factor B, insulin-like growth factor I, and transforming growth factor alpha messenger RNAs and their respective receptor messenger RNAs in primary human gastric carcinomas: in vivo studies with in situ hybridization and immunocytochemistry.

In situ hybridization and immunocytochemistry have been applied to investigate the expression of c-sis/platelet-derived growth factor (PDGF)-B, insulin-like growth factor (IGF)-I, and transforming growth factor alpha mRNAs and their respective receptor mRNAs in three primary human gastric carcinomas and in their adjacent nonmalignant mucosas. Expression of c-sis/PDGF-B mRNA and PDGF-receptor beta mRNA was seen in the tumor cells of the three gastric cancer specimens but not in their adjacent nonmalignant mucosa. The mRNA expression was accompanied by the expression of their respective protein products. IGF-I, IGF-I receptor, and epidermal growth factor receptor mRNAs were seen in both the tumor cells of the gastric cancer specimens and in nonmalignant mucosa. Transforming growth factor alpha mRNA was expressed in gastric tumor cells but not in nonmalignant mucosa. The coexpression of a potent "competence" growth factor, PDGF, and "progression" growth factors, IGF-I and transforming growth factor alpha, in the tumor cells of gastric carcinomas may contribute to their growth and maintenance.