Expression and clinical significance of leptin, the functional receptor of leptin (OB-Rb) and HER-2 in non-small-cell lung cancer: a retrospective analysis

Background The human epidermal growth factor receptor 2 (HER-2) and leptin/OB-R system have been reported to be intertwined in several cancer types. However, limited research has been conducted with regard to this interaction in lung cancers. In this study, we investigated the relationship between the expression levels of these proteins and the development, progression and prognosis of non-small-cell lung cancer (NSCLC). Methods The expression of leptin, OB-Rb and HER-2 was evaluated in 100 NSCLC specimens by immunohistochemistry, with normal lung tissue as controls. The relationships between their expression levels and clinicopathological factors were evaluated by correlation analysis. Univariate and multivariate analyses were used to determine the associations between the expression levels of these proteins and the survival of NSCLC patients. Results Leptin was expressed in 71 and 25% (P < 0.05) of NSCLC and normal lung tissues, respectively, while OB-Rb was expressed in 62 and 31% (P < 0.05), respectively. Overexpression of HER-2 was detected in 53% of NSCLC tissues versus 0% of normal lung tissues (P < 0.05). A significant association was found between the expression levels of leptin and OB-Rb (P = 0.024), and between tumor-node-metastasis (TNM) stage and HER-2 expression (P = 0.003). Univariate survival analysis showed that TNM stage (P < 0.001) and leptin expression (P = 0.009) influenced survival time. Multivariate analysis suggested that TNM stage [hazard ratio (HR) 1.63, 95% confidence interval (CI) 1.30-2.04, P < 0.001] and leptin expression (HR 1.69, 95% CI 1.01-2.80, P = 0.044) were independent prognostic factors for NSCLC. Conclusions The expression of leptin, OB-Rb and HER-2 was significantly higher in NSCLC tissues than in normal lung tissues. The expression of leptin is an independent prognostic factor for NSCLC.