Down-regulation of TGF-β RII expression is correlated with tumor growth and invasion in non-functioning pituitary adenomas

The two types of TGF-β receptors play a crucial role in TGF-β signaling. It has been reported that TGF-β signaling activity may be associated with the development and invasion of NFPAs. However, the role of TGF-β receptor signaling in NFPAs has not been fully explored. In this study, the expression of TGF-β RI and TGF-β RII in normal anterior pituitaries, invasive NFPAs and non-invasive NFPAs was analyzed by qRT-PCR, western blot, and immunohistochemistry. We found that TGF-β RII protein and mRNA levels gradually decreased from normal anterior pituitaries, noninvasive NFPAs to invasive NFPAs. There was no significant difference in the expression of TGF-β RI mRNA and protein level between normal anterior pituitaries and NFPAs. PCNA mRNA level was significantly higher in the invasive NFPAs than noninvasive NFPAs and PCNA mRNA had a negative correlation with TGF-β RII mRNA. We may draw the conclusion that low expression of TGF-β RII may contribute to the development and invasion of NFPAs and TGF-β RII promises to be a useful biomarker for the diagnosis of invasive NFPAs.