Long non-coding RNA NIFK-AS1 inhibits M2 polarization of macrophages in endometrial cancer through targeting miR-146a

Accumulating evidence suggested that tumor-associated macrophages played crucial roles in the progression of endometrial cancer. The aim of this study was to determine the role of lncRNA NIFK-AS1 in M2-like polarization of macrophages and further to investigate the effect of NIFK-AS1 modulating macrophage polarization on the proliferation, migration and invasion of endometrial cancer cells. Human peripheral blood mononuclear cells and tumor-associated macrophages were isolated from healthy volunteers and endometrial cancer patients, respectively. The expression of NIFK-AS1 and miR-146a were detected by qRT-PCR in tumor-associated macrophages or THP-1 monocytes differentiated macrophages. The expression of NIFK-AS1 and miR-146a were decreased and increased in tumor-associated macrophages of endometrial cancer patients, respectively. NIFK-AS1 overexpression suppressed the IL-4-induced M2 polarization of THP-1 macrophages. Moreover, we found that NIFK-AS1 overexpression inhibited the 17β-estradiol-induced proliferation, migration and invasion of endometrial cancer cells through suppressing M2-like polarization of macrophages. NIFK-AS1 could interact with miR-146a and increased the expression of Notch1 through downregulating miR-146a. Further experiments revealed that miR-146a overexpression attenuated the effect of NIFK-AS1 on suppressing the M2 polarization of macrophages and the estrogen-induced proliferation, migration and invasion of endometrial cancer cells. These findings indicated that NIFK-AS1 inhibited the M2-like polarization of macrophages via targeting miR-146a, thereby reducing the estrogen-induced proliferation, migration and invasion of endometrial cancer cells. Our study highlights the important role of NIFK-AS1 in regulating the polarization and function of tumor-associated macrophages in endometrial cancer and provides novel insight into the TAMs-mediated progression of endometrial cancer.