Survey of oncogene and growth factor/receptor gene expression in cancer cells by intron-differential RNA/PCR.

To elucidate the possible roles of proto-oncogenes and growth factors in estrogen-regulated cell proliferation of human breast and gynecologic cancers, we have determined the gene expressions of c-myc, transforming growth factor-alpha and beta 1 (TGF-alpha, beta 1) and epidermal growth factor receptor (EGFR) in a number of these cancer cell lines by using an intron-Differential (ID) RNA/PCR method, which differentially identifies the amplified cDNA from PCR products of genomic DNA contaminants. With this method, we demonstrated the expression of these genes, except EGFR, in an estrogen-dependent breast cancer cell line (CAMA-1). Our results show that TGF-alpha/EGF does not function as an autocrine factor in this cell line. Accordingly, it is unlikely that the TGF-alpha/EGFR system participates as a mediator in the estrogen-induced cell proliferation of CAMA-1 cells. The ID RNA/PCR method is a rapid, sensitive and specific technique for mRNA phenotyping and will have great clinical utility.