KDM5B is overexpressed in gastric cancer and is required for gastric cancer cell proliferation and metastasis.

Epigenetic alterations such as aberrant expression of histone-modifying enzymes have been implicated in tumorigenesis. KDM5B (also known as JARID1B) is a newly identified histone demethylase that regulates chromatin structure or gene expression by removing methyl residues from trimethylated lysine 4 on histone H3. Recent observations have shown oncogenic activity of KDM5B. However, the role of KDM5B in gastric cancer carcinogenesis remains unclear. In this study, we aimed to investigate the role of KDM5B in gastric cancer. Immunohistochemical analysis, western blotting, and qRT-PCR were used to measure the levels of KDM5B in gastric cancer cell lines, 45 pairs of gastric cancer tissues and the adjacent nonneoplastic tissues. KDM5B and shKDM5B were transfected into gastric cancer cells to investigate its role on regulating cell proliferation which was measured by MTT and colony formation assay. Cell's migration and invasion were measured by Transwell and Matrigel analysis in vitro. PCNA expression was measured by immunofluorescence staining and immunohistochemical analysis. The in vivo tumorigenesis and metastasis assays were performed in SCID mice. In clinical gastric cancer samples, we found that KDM5B expression was significantly up-regulated in cancer lesions compared with paired normal gastric tissues. By silencing or overexpressing KDM5B in gastric cancer cells, we found that KDM5B could promote cell growth and metastasis in vitro. An in vivo assay showed that KDM5B not only dramatically promoted gastric cancer cell xenograft formation and growth but also promoted gastric cancer cell metastasis in a liver metastasis model. Moreover, we demonstrated that KDM5B promoted gastric cancer metastasis via regulation of the Akt pathway. Our study provided evidence that KDM5B functions as a novel tumor oncogene in gastric cancer and may be a potential therapeutic target for gastric cancer management.