Gene expression of transforming growth factor β receptors I and II in non-small-cell lung tumors

Transforming growth factor (TGF)β inhibits normal epithelial cell proliferation. A decreased expression of TGFβ receptors (TβR) has been associated with loss of TGFβ sensitivity and enhanced tumor progression in many types of cancer. Although lung cancer is one of the leading causes of cancer death, a comparative analysis of TβR mRNA and protein expression in non-small-cell (NSC) lung tumors has not been performed. Lung tumor tissues and control non-lesional lung tissues were obtained from 17 patients undergoing thoracotomy for primary NSC lung tumors in clinical stage II. Each tissue sample was studied for TβRI and TβRII mRNA and immunoreactive protein expression, using a semi-quantitative reverse transcription-PCR method, and a quantitative immunohistochemistry method, respectively. TβRI protein expression was higher in tumors than in controls ( p=0.0005) and a similar trend was present at the mRNA level. TβRII protein expression was not significantly different between tumors and controls, however an intense peri-nuclear staining for TβRII was observed in several tumor cells. TβRII mRNA levels were lower in tumors than in controls ( p=0.005) and an inverse relation between TβRII mRNA and protein expression was detected in tumors ( p=0.0013). Our findings suggest an altered function of the TβR system in NSC lung cancer.