Reduced transcription of the Smad4 gene during pulmonary carcinogenesis in idiopathic pulmonary fibrosis

Patients with idiopathic pulmonary fibrosis (IPF) have an increased risk of developing lung cancer. To identify key molecules involved in malignant transformation in IPF, we analyzed the expression profiles of lung and lung tumor tissue from patients with lung cancer and IPF (lung cancer/IPF) using cDNA arrays and real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Reduced expression of the Smad4 gene was identified in all eight tumor samples from the lung cancer/IPF patients using real-time RT-PCR. Expression levels of Smad4 were significantly lower in tumors from lung cancer/IPF patients than in those from lung cancer patients without IPF or in lung cancer cell lines (p