CEBPA Restrains the Malignant Progression of Breast Cancer by Prompting the Transcription of SOCS2.

The suppressor of cytokine signaling 2 (SOCS2) has been identified to act as a tumor suppressor in breast cancer (BC) progression. However, the action of SOCS2 in macrophage polarization in BC cells has not been reported yet. The qRT-PCR and western blotting were adopted for detecting the levels of mRNAs and proteins. The macrophage M2 polarization was analyzed by flow cytometry. Analyses of cell oncogenic phenotypes and tumor growth were conducted using 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, scratch, Transwell, tube formation assays in vitro, and tumor xenograft assay in vivo, respectively. The interaction between CEBPA (CCAAT Enhancer Binding Protein Alpha) and SOCS2 was confirmed using bioinformatics analysis and dual-luciferase reporter assay. SOCS2 was lowly expressed in BC tissues and cells. Functionally, overexpression of SOCS2 inhibited macrophage M2 polarization, and impaired BC cell proliferation, angiogenesis, and metastasis. Mechanistically, CEBPA bound to the promoter region of SOCS2, and promoted its transcription. A low CEBPA expression was observed in BC tissues and cells. Forced expression of CEBPA also suppressed macrophage M2 polarization, BC cell proliferation, angiogenesis, and metastasis. Moreover, the anticancer effects mediated by CEBPA were abolished by SOCS2 knockdown. In addition, CEBPA overexpression impeded BC growth in nude mice by regulating SOCS2. CEBPA suppressed macrophage M2 polarization, BC cell proliferation, angiogenesis, and metastasis by promoting SOCS2 transcription in a targeted manner.