ABSTRACT
Objective: To explore the expression of Ephrin receptor A7 (EphA7) in the patients with small cell lung cancer (SCLC) and its clinical significance. Methods: The expression of EphA7 mRNA in SCLC cell lines and tissues was analyzed by the Cancer Cell Line Encyclopedia (CCLE) and Oncomine databases, respectively. Seventy-three paraffin-embedded lung cancer specimens and six adjacent normal lung tissue samples from SCLC patients who underwent lobectomy or pneumonectomy resection in Tianjin Medical University Affiliated Cancer Hospital and Institution from January 2011 to December 2014 were collected. The expression of EphA7 protein was assessed by immunohistochemistry. The relationship between the expression of EphA7 protein and other clinicopathological factors was analyzed by x2 test. Kaplan-Meier survival curve and COX proportional hazard model were used to analyze the relationship between these clinicopathological parameters (including EphA7 expression) and the prognosis of SCLC patients. Results: The expression of EphA7 mRNA in SCLC cell lines was the highest among the 1 457 cell lines included in CCLE database. Three datasets of EphA7 mRNA expression in SCLC tissues were obtained from the Oncomine database. Compared with the normal lung tissues and non-small cell lung cancer, the expression level of EphA7 mRNA was relatively higher in SCLC tissues. The positive expression rate of EphA7 protein reached 72.6% (53/73) in the 73 patients with SCLC. The expression of EphA7 protein was significantly associated with lymph node metastasis and TNM stage (both P < 0.05). After adjusting other factors, it was found that the positive expression of EphA7 protein was an independent prognostic factor for the overall survival (OS) of SCLC patients [hazard ratio (HR) = 2.369, 95% confidence interval (CI): 1.075-5.219, P < 0.05], while TNM stage was an independent prognostic factor for both OS (HR = 2.273, 95% CI: 1.252-4.124, P < 0.05) and progression-free survival (PFS) (HR = 1.898, 95% CI: 1.088-3.312, P < 0.05) of SCLC patients, respectively. Conclusion: EphA7 mRNA and protein are highly expressed in SCLC tissues. The expression of EphA7 protein and TNM stage may be independent factors for the prognosis of SCLC patients.