The reciprocal regulation loop of Notch2 pathway and miR-23b in controlling gastric carcinogenesis.

Gastric carcinoma is one of the most common malignancies and the third highest cause of global cancer-related death. Notch2 receptor intracellular domain (N2IC), the activated form of Notch2 receptor, enhances gastric carcinogenesis. MicroRNAs (miRNAs) act as either oncogenes or tumor suppressors in tumorigenesis and cross-talk with Notch pathways. Herein, microRNA-23b (miR-23b) was identified as a Notch2 receptor-related miRNA and its role in gastric carcinogenesis was investigated. Levels of miR-23b in stomach adenocarcinoma samples were down-regulated, whereas those of Notch2 receptor, v-ets erythroblastosis virus E26 oncogene homolog 1 (Ets1), and E2F1 transcripts were up-regulated. Results also showed that N2IC down-regulated miR-23b expression in gastric cancer cells through up-regulating E2F1. The miR-23b inhibited gastric tumorigenesis including growth, viability, epithelial-mesenchymal transition, and abilities of colony formation, migration, invasion, and tumorsphere formation. Mechanistically, miR-23b suppressed tumor progression and pluripotency gene expression and affected tumorsphere ultra-structure in gastric cancer cells via targeting Notch2 receptor or Ets1. Furthermore, miR-23b diminished the xenografted tumor growth and lung metastasis of SC-M1 gastric cancer cells through Notch2 pathway. Our results suggest that Notch2 pathway and miR-23b interplay in a reciprocal regulation loop in gastric cancer cells and this axis plays an important role in gastric carcinogenesis.