Expression of a novel matrix metalloproteinase regulator, RECK, and its clinical significance in resected non-small cell lung cancer

The reversion-inducing-cysteine-rich protein with Kazal motifs (RECK) was initially isolated as a transformation-suppressor gene by expression cloning and found to encode a membrane-anchored regulator of the matrix metalloproteinases (MMPs). Experimental studies have shown that RECK can suppress tumour - invasion, metastasis and angiogenesis. However, the clinical impact of RECK remains unclear. To assess the clinical significance of RECK-expression in non-small cell lung cancer (NSCLC), a total of 171 patients with completely resected pathological stage (p-stage) I-IIIA NSCLC were retrospectively examined. Expression of RECK and vascular endothelial growth factor (VEGF) in tumour tissues was assessed by immunohistochemical staining (IHS). Intratumoural microvessel density (IMVD), a measurement of angiogenesis, was also determined by IHS using an anti-CD34 antibody. A significant inverse correlation between RECK-expression and tumour angiogenesis was documented; the mean IMVD in tumours with strong RECK-expression (157.1) was significantly lower than that observed in tumours with weak RECK-expression (194.5; P = 0.008). Interestingly, this inverse correlation was seen only when VEGF was strongly expressed, which suggests that RECK could suppress the angiogenesis induced by VEGF. The 5-year survival rate for patients with tumours with strong RECK-expression (75.8%) was significantly higher than that for patients with weakly expressing tumours (54.3%; P = 0.016). Subset analyses showed that the prognostic impact of RECK-status was evident in patients with either adenocarcinoma, poorly differentiated tumours, or p-stage IIIA disease. A multivariate analysis confirmed that reduced RECK-expression was an independent and significant factor in predicting a poor prognosis (P = 0.009; Hazard ratio (HR), 0.474 with a 95% Confidence interval (CI) of 0.271-0.830). In conclusion, RECK-status is a significant prognostic factor correlated with tumour angiogenesis in NSCLC patients.