TGF-beta 1 mRNA expression in clinical breast cancer and its relationship to ER mRNA expression

Eighty nine primary breast cancers were investigated for the expression of TGF-beta 1 and ER mRNA using PCR of reverse transcribed RNA. PCR products were validated using Southern blots and hybridization with radiolabelled cDNA probes. TGF beta 1 mRNA was found to be expressed in 56/89 (63%) of the breast cancers while ER mRNA was expressed in 23/89 (26%) of the tumours. Using chi-square analysis TGF-beta mRNA expression was found to correlate significantly with ER mRNA expression (p < 0.001), in that virtually all tumours that expressed ER mRNA co-expressed TGF beta 1. In tumours that were ER mRNA negative, TGF beta 1 expression was more variable. These results suggest that during tumour progression, ER expression is lost more frequently than is growth factor expression.