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Continuous estrogen signaling is thought to be the main mechanism causing endometrial cancer (EC). Studies have demonstrated that CD163+ macrophages could promote the development of estrogen-dependent EC, but the mechanisms involved remain unclear. We found that CD163+ macrophages were the dominant macrophages in atypical endometrial hyperplasia and cancer, and their infiltration was positively associated with ERα expression. CD163+ macrophages mainly increased ERα protein levels but with little upregulatory effect on ESR1 (ERα coding gene) transcripts. The ubiquitin-editing enzyme A20, screened from the endometrial microarray obtained from mice receiving a high-fat diet and sustained estrogen-intervened, was highly expressed in endometrial lesions rich with CD163+ macrophages, and positively correlated with ERα expression. Similarly, A20 and ERα were both upregulated by CD163+ macrophages via cytokines such as IL1α, IL17A and TNFα. Mechanistically, A20 overexpression in EC cells prolonged ERα protein half-life without affecting ESR1 transcripts. A20 increased functional ERα protein levels and enhanced estrogen-driven EC cell proliferation through preventing ERα protein degradation by its deubiquitinase activity. Our study revealed that A20-mediated deubiquitination of ERα might be an important mechanism by which CD163+ macrophages sensitize EC cells to estrogen.

Continuous estrogen signaling is thought to be the main mechanism causing endometrial cancer (EC). Studies have demonstrated that CD163