Reduced expression of claudin-7 is associated with poor outcome in non-small cell lung cancer.

Claudin-7 is a tight junction protein that plays an important role in tumorigenesis, tumor invasion and metastasis. We examined the clinical significance of claudin-7 expression in 75 postsurgical non-small cell lung cancer (NSCLC) patients. Claudin-7 expression was measured immunohistochemically and was found to be high in 25 patients (33.3%) and low in 50 (66.7%). Survival was significantly poorer in patients with claudin-7-low than in those with claudin-7-high NSCLCs (P=0.024). In particular, survival was significantly poorer in patients with claudin-7-low than in those with claudin-7-high squamous cell carcinomas (P=0.011). A reduced expression of claudin-7 was associated with poor outcome in NSCLCs. Claudin-7 may thus be a useful biomarker and a potential therapeutic target in patients with NSCLC.