Prognostic Value of Highly Expressed Type VII Collagen (COL7A1) in Patients With Gastric Cancer

Collagen is a major component in the tumor microenvironment. This study reveals a novel biomarker candidate, type VII collagen (COL7A1), in patients with gastric cancer. To identify genes differentially expressed in gastric cancer tissue, we analyzed cancerous (n = 20) and noncancerous tissues (n = 13) using a DNA microarray. To perform immunohistochemistry and validate the upregulation of COL7A1 expression, we collected 200 more gastric cancer tissues and 100 normal gastric tissues from 200 randomly selected patients who underwent gastrectomy for gastric cancer between January 2010 and December 2013. The correlations between COL7A1 expression and clinicopathological parameters and patients' overall survival (OS) were analyzed. In the microarray, COL7A1 was upregulated in gastric cancer tissue compared with normal tissue. In the immunohistochemistry study, COL7A1 was more highly expressed in cancer tissue than in normal tissue (p = 0.001). Patients with intracellular COL7A1 expression had significantly poorer five-year OS than those with only extracellular expression (41.5 versus 69.7%, p = 0.001), and the site of expression was an independent prognostic factor of OS (hazard ratio 2.00, 95% CI 1.26-3.16, p = 0.003). Also, we found a significant association between the COL7A1 immunohistochemistry score and distant metastasis (high versus low, odds ratio 4.45, 95% CI 1.40-14.16, p = 0.011). The site and total immunohistochemistry score of COL7A1 expression in gastric cancer showed prognostic significance for OS and distant metastasis, respectively. COL7A1 could be a novel biomarker with diagnostic and therapeutic value.