Stage-related plasma values of transforming growth factor-beta1 are steroid receptors dependent

Abstract

Transforming growth factor-beta1 (TGF-beta1) is a biomarker associated with the progression of breast cancer, characteristic by switching activity from tumor suppressor in early stages to tumor promoter at advanced disease. However, what cause this switch is still not clear. On the other hand, the relationship between steroid receptors (estrogen ER and progesterone PR) as the major discriminators of breast cancer phenotype and this paradoxical biomarker is not fully determined. In this pilot study on 52 breast cancer patients, quantitative plasma values of TGF-beta1 were determined by quantitative ELISA and steroid receptor content was measured in cytosol fraction of breast cancer tissue using dextran-coated (DCC) method. We tried to investigate the possibility that steroid receptor status of patients at different stages of disease could be the trigger that somehow causes variation of TGF-beta1 plasma levels. In nonmetastatic breast cancer patients, there was no statistically significant increase in the plasma levels of TGF-beta1, when patients are stratified by steroid receptor status (ER- vs. ER+, PR- vs. PR+). We found for the first time, that indeed in metastatic breast cancer statistically significant elevated levels of TGF-beta1 are related to negative steroid receptor status and moreover that, there is correlation between quantitative values of these parameters in this stage. This finding deserves further investigation because it could provide a new insight into more aggressive nature of steroid receptor negative tumors.