EXPRESSION OF TRANSFORMING GROWTH-FACTOR-BETA MESSENGER-RNA ISOFORMS IN HUMAN BREAST-CANCER

Using an RNAse protection assay, expression of messenger RNA for isofo rms of TGF-beta was determined in a series of breast cancers. Of 50 tu mours, 45 (90%) expressed TGF-beta(1) mRNA, 39 (78%) expressed TGF-bet a(2), and 47 (94%) expressed TGF-beta(3). Patterns of expression varie d between different tumours: 37 (74%) cancers expressed all three TGF- beta isoforms, ten (20%) expressed only two isoforms and two expressed TGF-beta(1) alone. One sample showed no evidence of TGF-beta mRNA exp ression. Although most breast cancers expressed mRNA for at least one isoform of TGF-beta, there were differences in patterns of mRNA expres sion between individual tumours. The relatively small number of tumour s examined precluded detailed analysis between expression and other cl inical parameters, but a significant association was identified betwee n one aspect of isoform expression and lymph node status, in that the majority of tumours expressing all three isoforms were associated with lymph node involvement, whereas tumours without one or more isoform w ere usually lymph node negative (P = 0.025 by Fisher's exact test).