Histone demethylase JMJD2B is required for tumor cell proliferation and survival and is overexpressed in gastric cancer

► JMJD2B is required for cell proliferation and in vivo tumorigenesis. ► JMJD2B depletion induces apoptosis and/or cell cycle arrest. ► JMJD2B depletion activates DNA damage response and enhances p53 stabilization. ► JMJD2B is overexpressed in human primary gastric cancer. Epigenetic alterations such as aberrant expression of histone-modifying enzymes have been implicated in tumorigenesis. Jumonji domain containing 2B (JMJD2B) is a newly identified histone demethylase that regulates chromatin structure or gene expression by removing methyl residues from trimethylated lysine 9 on histone H3. Recent observations have shown oncogenic activity of JMJD2B. We explored the functional role of JMJD2B in cancer cell proliferation, survival and tumorigenesis, and determined its expression profile in gastric cancer. Knocking down JMJD2B expression by small interfering RNA (siRNA) in gastric and other cancer cells inhibited cell proliferation and/or induced apoptosis and elevated the expression of p53 and p21CIP1 proteins. The enhanced p53 expression resulted from activation of the DNA damage response pathway. JMJD2B knockdown markedly suppressed xenograft tumor growth in vivo in mice. Moreover, JMJD2B expression was increased in primary gastric-cancer tissues of humans. Thus, JMJD2B is required for sustained proliferation and survival of tumor cells in vitro and in vivo, and its aberrant expression may contribute to the pathogenesis of gastric cancer.