Differential expression of transforming growth factors-beta1, -beta2 and -beta3 in human colon carcinoma

Transforming growth factor (TGF)-beta is a protein family which affects multiple cellular functions including survival, proliferation, differentiation and adhesion. Among the three known isoforms, TGF-beta1 is commonly overexpressed in solid malignancies. Recent studies in knock-out mice demonstrated non-redundant roles of different TGF-beta isoforms in development. The present study was performed to assess tumour-associated expression of the three TGF-beta isoforms in colon carcinoma. We report that colon carcinoma progression is associated with gradual and significant increases in expression of TGF-beta1 and TGF-beta2 mRNA and proteins. By contrast, TGF-beta3 expression was detected in normal colonic mucosa and, at slightly higher levels, in tumour tissues. In addition, plasma levels of both TGF-beta1 and TGF-beta2 were significantly higher in cancer patients when compared with unaffected individuals. Taken together, our results indicate distinct expression patterns of the three TGF-beta isoforms in colon carcinoma cells and possible systemic effects of TGF-beta1 and TGF-beta2 in tumour patients.