Article

The complexities of TGF-β action during mammary and squamous cell carcinogenesis

Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, California 94143-0512, USA.
Current pharmaceutical biotechnology (Impact Factor: 2.51). 05/2011; 12(12):2138-49. DOI: 10.2174/138920111798808284
Source: PubMed

ABSTRACT Many advanced tumors produce excess amounts of Transforming Growth Factor-β (TGF-β), which is a potent growth inhibitor of normal epithelial cells. However, in tumors its homeostatic action on cells can be diverted along several alternative pathways. Thus, TGF-β signaling has been reported to elicit a preventative or tumor suppressive effect during the earlier stages of tumorigenesis, but later in tumor development, when carcinoma cells become refractory to TGF-β-mediated growth inhibition, response to TGF-β signaling elicits predominantly tumor progressing effects. This is not a simple switch from suppression to progression, but more like a rheostat, involving multiple complementary and antagonizing activities that slowly tip the balance from one to the other. This review will focus on the multiple activities of TGF-β in regulation of two epithelial tumor types, namely squamous cell carcinoma and breast cancer. Basic findings in current mouse models of cancer are presented, as well as a discussion of the complicating issue of outcome of altered TGFβ signaling depending on genetic variability between mouse strains. This review also discusses the role TGF-β within the tumor microenvironment particularly its ability to polarize the microenvironment towards a pro-tumorigenic milieu.

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