Osteopontin is associated with decreased apoptosis and αv integrin expression in lung adenocarcinoma

Osteopontin (OPN) is a glycoprotein involved in invasion, progression and metastasis of many carcinomas. It contains several functional domains including binding sites for αv integrins, cell surface molecules playing a major role in mediating cell migration and adhesion. The aim of the study was to evaluate the expression of osteopontin in human non-small cell lung cancer (NSCLC) and to determine its possible prognostic significance as well as relation to apoptosis and αv integrin expression. We analyzed 111 surgically resected NSCLC for immunohistochemical expression of OPN and αv integrin. OPN expression was compared to apoptotic rate and clinicopathological parameters such as tumor size, histological grade, lymph node status, pT, and TNM stage. Apoptotic rate was measured by TUNEL staining method. OPN expression in NSCLC was significantly higher in lung adenocarcinomas (AC) then in squamous cell carcinomas (p < 0.001). There was no correlation between OPN expression and clinicopathological parameters. The level of OPN expression in AC was associated with decreased apoptotic activity of tumor cells (p = 0.006), and correlated with αv integrin expression (p = 0.048), particularly in low stage tumors (p = 0.013). Prolonged tumor cell survival in lung AC due to OPN and αv integrin overexpression may have an impact on tumor progression and resistance to therapy.