NRAGE promotes cell proliferation by stabilizing PCNA in a ubiquitin–proteasome pathway in esophageal carcinomas

作者：Qingyuan Yang, Chao Ou, Mei Liu, Weifan Xiao, Chuanjun Wen, Fenyong Sun · 发表于：Carcinogenesis · 年份：2014 · DOI：10.1093/carcin/bgu084 · 被引用次数：52 · 研究领域：Ubiquitin and proteasome pathways、Immunotherapy and Immune Responses、Peptidase Inhibition and Analysis

Neurotrophin receptor-interacting melanoma antigen-encoding gene homolog (NRAGE) is generally recognized as a tumor suppressor as it induces cell apoptosis and suppresses cell metastasis. However, it has recently been reported that NRAGE is overexpressed in lung cancer, melanoma and colon cancer, implicating a complicated role of NRAGE as we have expected. In the study, we aim to elucidate the functional roles and molecular mechanisms of NRAGE in esophageal carcinoma. We found that both NRAGE mRNA and protein were significantly overexpressed in esophageal tumor tissues. Consistently, both in vivo and in vitro analyses demonstrated that knockdown of NRAGE apparently inhibited cell growth, and cell cycle analysis further demonstrated that NRAGE knockdown cells were mainly arrested in G2M cell phase, accompanied with an apparent reduction of S phase. In the process of exploring molecular mechanisms, we found that either knockdown in vitro or knockout in vivo of NRAGE reduced proliferating cell nuclear antigen (PCNA) protein, expression of which could completely rescue the inhibited proliferation in NRAGE defective cells. Furthermore, NRAGE physically interacted with PCNA in esophageal cancer cells through DNA polymerase III subunit, and knockdown of NRAGE facilitated PCNA K48-linked polyubiquitination, leading PCNA to the proteasome-dependent degradation and a ubiquitin-specific protease USP10 was identified to be a key regulator in the process of K48 polyubiquitination in NRAGE...