DNA methyltransferase expression in triple-negative breast cancer predicts sensitivity to decitabine

作者：Jia Yu, Bo Qin, Ann M. Moyer, Somaira Nowsheen, Tongzheng Liu, Sisi Qin, Yongxian Zhuang, Duan Liu, W. Lu, Krishna R. Kalari, Daniel W. Visscher, John A. Copland, Sarah A. McLaughlin, Alvaro Moreno‐Aspitia, Donald W. Northfelt, Richard J. Gray, Zhenkun Lou, Vera J. Suman, Richard Weinshilboum, Judy C. Boughey, Matthew P. Goetz, Liewei Wang · 发表于：Journal of Clinical Investigation · 年份：2018 · DOI：10.1172/jci97924 · 被引用次数：215 · 研究领域：Epigenetics and DNA Methylation、Cancer Genomics and Diagnostics、Histone Deacetylase Inhibitors Research

Triple-negative breast cancer (TNBC) is a heterogeneous disease with poor prognosis that lacks targeted therapies, especially in patients with chemotherapy-resistant disease. Since DNA methylation-induced silencing of tumor suppressors is common in cancer, reversal of promoter DNA hypermethylation by 5-aza-2'-deoxycytidine (decitabine), an FDA-approved DNA methyltransferase (DNMT) inhibitor, has proven effective in treating hematological neoplasms. However, its antitumor effect varies in solid tumors, stressing the importance of identifying biomarkers predictive of therapeutic response. Here, we focused on the identification of biomarkers to select decitabine-sensitive TNBC through increasing our understanding of the mechanism of decitabine action. We showed that protein levels of DNMTs correlated with response to decitabine in patient-derived xenograft (PDX) organoids originating from chemotherapy-sensitive and -resistant TNBCs, suggesting DNMT levels as potential biomarkers of response. Furthermore, all 3 methytransferases, DNMT1, DNMT3A, and DNMT3B, were degraded following low-concentration, long-term decitabine treatment both in vitro and in vivo. The DNMT proteins could be ubiquitinated by the E3 ligase, TNF receptor-associated factor 6 (TRAF6), leading to lysosome-dependent protein degradation. Depletion of TRAF6 blocked decitabine-induced DNMT degradation, conferring resistance to decitabine. Our study suggests a potential mechanism of regulating DNMT protein degradati...