DETERMINATION OF TRANSFORMING GROWTH-FACTOR BETA(1) MESSENGER-RNA EXPRESSION IN BREAST CARCINOMAS BY IN-SITU HYBRIDIZATION

The expression of transforming growth factor beta, (TGF-beta(1)) mRNA has been determined in 16 breast carcinomas using in situ hybridizatio n and compared with TGF-beta protein as detected by antibodies against TGF-beta(1), and TGF-beta(1), plus TGF-beta(2). Digoxigenin-labelled riboprobes were used, with alkaline phosphatase and immunogold silver detection systems. TGF-beta(1) mRNA was only detected in carcinomas in which TGF-beta(1) protein was found (9 of 16 cases) and not in those with prominent reactivity for TGF-beta(2). RNA. preservation was poor in two other cases in which TGF-beta(1) protein had been detected. In general, those tumours with greater numbers of cells labelled for TGF- beta(1) mRNA had prominent reactivity for TGF-beta(1) protein. The mRN A was localized to cancer cells with no labelling of stromal cells, al though in a small number of cases scanty staining for TGF-beta(1) prot ein had been observed in stromal cells. The incidence of detection of TGF-beta(1), mRNA is lower than the published data from Northern analy sis studies of breast carcinomas, suggesting that only higher levels o f TGF-beta(1) mRNA expression are being detected by in situ hybridizat ion. However, this approach has provided useful information about the cellular sites of expression of TGF-beta(1) in breast carcinomas.