Expression and their clinical significance of SSTR2A, SSTR5 and EGFR in non-small cell lung cancer

Abstract

Somatostatin receptor (SSTR), as a marker gene in tumors, is being valued gradually. With five subtypes have been identified, many researches are carried out to explore the amino acid sequence of SSTR family members, the molecular biological characteristics, the distribution and expression in the normal tissue and the tumor, and their specific ligands. In this study, the expression and significance of SSTR (SSTR2A, SSTR5) and epidermal growth factor receptor (EGFR) in human non-small cell lung cancer (NSCLC) were investigated, and the relationship among them were evaluated. The expressions of SSTR2A, SSTR5 and EGFR in 62 NSCLC tissues and 7 lung tissues adjacent to the cancer tissues were detected by immunohistochemical method (SP method). All cases were followed up. In 62 cases of NSCLC, the positive rate of SSTR2A and SSTR5 expression was 48.4% (30/62) and 71.0% (44/62) respectively. The positive rate of SSTR2A and SSTR5 was closely related to TNM stage (P < 0.05), but not to other clinical characteristics of NSCLC (P > 0.05). The positive rate of EGFR expression was 56.5% (35/62), but 0 in 7 lung tissues adjacent to the cancer tissues. The positive rate of EGFR was not related to the age, sex, smoking or not, tumors histological type, tumor size, TNM stage, differentiation classification and the lymph node metastasis (P > 0.05). There was negative relation between the expression of SSTR2A, SSTR5 and EGFR in NSCLC. The 3-year survival rate of patients with SSTR2A and SSTR5 expression was 64.52% and 65.91% respectively, 45.16% and 22.22% for those without expression (P < 0.05); The 3-year survival rate of patients with EGFR expression was 30.77% and 69.44% for those without expression (P < 0.05 ). The expression of SSTR and EGFR is significantly upregulated in NSCLC and a negative relation exists between their expressions. Detection of expression of SSTR2A, SSTR5 and EGFR might be helpful to evaluate lymph node metastasis, pathological stages and prognosis of NSCLC.