ATF4 regulates CCL2 expression to promote endometrial cancer growth by controlling macrophage infiltration.

Activating transcription factor 4 (ATF4), an endoplasmic reticulum stress-inducible transcription factor, plays important roles in cancer progression and resistance to therapy. However, no report is available about its roles in endometrial cancer (EC). In this study, we found that ATF4 is commonly expressed in EC cell lines. Loss-of-function studies in two EC cell lines showed that ATF4 knockdown suppresses tumor growth of EC in vivo without influencing cell proliferation in vitro. And xenograft tumors derived from ATF4-knockdown cells had reduced M2 macrophage infiltration. In clinical specimens, ATF4-high expressing tumors indeed contained more macrophage infiltration compared to those with lower ATF4 expression. Moreover, we identified that ATF4-mediated chemokine CCL2 expression ultimately results in macrophage infiltration and tumor growth of EC. Taken together, our findings suggest that ATF4 contributes to tumor growth of EC by promoting CCL2 and subsequent recruitment of macrophage, and that ATF4/CCL2 axis might be a potential therapeutic target for EC.