Clinical significance of retinoic acid-induced protein I expression in human gastric cancer

Abstract

Objective To investigate the clinical significance and regulation of retinoic acid-induced protein I (RIG-I) in human gastric cancer. Methods Immunohistochemistry was used to study RIG-I expression in gastric cancer and normal tissues. We used Wilcoxon test to analyze the difference of RIG-I expression levels in cancer and normal tissues. Chi-square and Log-rank tests were used to analyze the RIG-I expression in cancer tissues in relation to patients’ clinical parameters and prognoses respectively. The gastric cancer cell lines SGC-7901 and AGS were used to construct the stable knockdown expression of RIG-I using RNA interference (RNAi) method. The cell counting kit-8 (CCK-8), wound healing, and Transwell assays were used to examine the cellular function after RIG-I knockdown of these cells. Results RIG-I expression level in human gastric cancer tissues was significantly lower than that in adjacent normal tissues (U=1 490, P=0.001). The ratio of higher RIG-I expression in cancer patients with pathological stage (Ⅲ-Ⅳ) was significantly lower than that in normal tissues (χ2=4.668, P=0.031). The overall survival of the patients with higher RIG-I expression was significantly longer than that with lower RIG-I expression (P=0.023). The COX model showed that the age (P=0.047), TNM stage (P=0.039) and the RIG-I expression (P=0.007) could be used as independent prognostic predictors for cancer patients. CCK-8 assay showed that at the time points of 48 h and 72 h after culture, the A450 value in LV-RIG-I-short hairpin RNA (shRNA) group was significantly higher than that in LV-NC group (for SGC7901: P=0.000 and P=0.000 respectively; for AGS: P=0.002 and P=0.016 respectively). The wound healing assay showed that the cell migration abilities in LV-RIG-I-shRNA group was significantly stronger than LV-NC group (for SGC7901: P=0.001; for AGS: P=0.004). The Transwell assay showed that the cell invasion abilities in LV-RIG-I-shRNA group was significantly stronger than that in LV-NC group (for SGC7901: P=0.032; for AGS: P=0.016). Conclusion RIG-I plays important roles in gastric cancer progression, its knockdown could promote proliferation, migration and invasion of cancer cells, and thus could be used as potential therapeutic target for gastric cancer. Key words: Retinoic acid-induced protein I; Gastric cancer; RNA interference; Immunohistochemistry