Elevated Expression of The Rhythm Gene NFIL3 Promotes The Progression of TNBC By Activating NF-κB Signaling Through Suppression of NFKBIA Transcription

Abstract

Background: Epidemiological studies have confirmed that abnormal circadian rhythms are associated with tumorigenesis in breast cancer. However, few studies have investigated the pathological roles of rhythm genes in breast cancer progression. Methods: The expressions of NFIL3 and NFKBIA were measured by Western blot, qRT–PCR and IHC analysis. The proliferation and metastasis of two TNBC cell lines were analyzed by cell counting assays, clone formation assays, subcutaneous tumor formation assay, wound healing assays, transwell assays and the mouse tail vein injection model.Results: We evaluated the aberrant expression of 32 rhythm genes in breast cancer and identified that nuclear factor interleukin 3 regulated (NFIL3) expression is significantly altered in triple-negative breast cancer (TNBC). We found that NFIL3 inhibits its own transcription, and thus, downregulated NFIL3 mRNA indicates high expression of NFIL3 protein in breast cancer. Functional studies demonstrated that NFIL3 promotes the proliferation and metastasis of TNBC cells in vitro and in vivo. Higher expression of NFIL3 is associated with poor prognosis of patients with TNBC. Gene enrichment assays revealed that NFIL3 primarily regulates cancer-associated inflammation. Correlation analysis showed that expression of NFIL3 is associated with infiltration level of various immune cells in breast cancer. We further demonstrated that NFIL3 enhances the activity of NF-κB signaling. Mechanistically, we revealed that NFIL3 directly suppresses the transcription of NFKBIA, which blocks the activation of NF-κB and inhibits the progression of TNBC cells in vitro and in vivo. Moreover, we showed that enhancing NF-κB activity by repressing NFKBIA largely mimics the oncogenic effect of NFIL3 in TNBC, and anti-inflammatory strategies targeting NF-κB activity block the oncogenic roles of NFIL3 in TNBC. Conclusion:NFIL3 promotes the progression of TNBC by suppressing NFKBIA and then enhancing NF-κB signaling-mediated cancer-associated inflammation. This study may provide a new target for TNBC prevention and therapy.