Downregulation of REV-ERBα is associated with the progression of lung adenocarcinoma

BACKGROUND: The nuclear receptor REV-ERBα (nuclear receptor subfamily 1, Group D member 1, NR1D1) is one of the essential components of the circadian clock which modulates cell proliferation, glucose metabolism, inflammation, and many other biological processes. Modulation of these processes are also relevant to cancer development. Previous studies have suggested that activation of REV-ERBα correlates with cancer cell senescence and death, but how REV-ERBα play roles in tumor progression require further elucidation. METHODS: We investigated the expression of REV-ERBα in clinical samples by immunohistochemistry (IHC). REV-ERBα is downregulated by shorth hairpin RNA (shRNA). The gene expression level of each group was detected by Western blot analysis. The effects of REV-ERBα downregulation on apoptosis and cell cycles was assessed by flow cytometry assay. A549 cell growth curve under different treatments measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Cell invasion ability under different treatments was measured by Transwell assay. Immunostaining analysis was also used for evaluating the effects of downregulation of REV-ERBα on nuclear factor-κB (NF-κB). RESULTS: Compared to 81.8% (54/66) of samples exhibiting a lower expression level of REV-ERBα in cancer tissue than in paired normal tissue, only 18.2% (12/66) were higher or equally expressed in lung cancer tissue. Furthermore, downregulation of REV-ERBα by RNA interference can significantly enhance the transcription of nuclear factor-κB (NF-κB), while the expression of p53 remained the same. Downregulation of REV-ERBα was also shown to stimulate the invasion and promote the proliferation of lung adenocarcinoma cell line A549. CONCLUSIONS: Our findings suggest that tumorigenesis and progression of lung carcinoma is relevant to downregulation or inhibition of REV-ERBα. This pathophysiological process also correlates with regulation of the NF-κB signaling pathway, indicating that REV-ERBα is a potential target of lung cancer therapy.