The role and mechanism of circadian clock gene BMAL1 in the proliferation and metastasis of nasopharyngeal carcinoma by inhibition TGF-β1/Smads pathway.

Abstract

6027 Background: To explore the molecular mechanism of biological clock gene BMAL1 inhibiting the proliferation and metastasis of nasopharyngeal carcinoma(NPC). Methods: 1. IHC detected the expression of BMAL1 in 41 cases of nasopharyngeal chronic inflammatory tissue and 71 cases of NPCtissue. PCR and Western blot measured the expression levels of BMAL1 in NP69 in NPC cells and human immortalized nasopharyngeal epithelial cells, respectively. 2. To detect the effect of BMAL1 on the proliferation capacity of NPCcells in vitro and in vivo; Scratch healing and Transwell invasion migration experiments detected the effect of BMAL1 on the invasion and migration ability of NPCcells in vitro. Fluorescence in vivo imaging and HE staining to determine the transfer of nude mouse tail intravenous injection model. PCR and Western blot detect the effect of BMAL1 on the expression of EMT-related markers at the transcriptional and protein levels in NPC cells. 3. A series of molecular biological means such as bioinformatics technology, ChIP experiment, double luciferase reporter gene experiment, immunofluorescence colocalization experiment and Co-IP were used to verify its mechanism. Results: 1. The expression of BMAL1 in NPCtissues and cells is reduced. The expression of BMAL1 in NPC tissues was associated with the M stage of nasopharyngeal carcinoma patients (p=0.006). 2. Overexpression of BMAL1 can inhibit the proliferation, invasion and migration ability of nasopharyngeal cancer cells, while knocking down BMAL1 is the opposite. Overexpression of BMAL1 inhibits EMT of NPCcells. 3. There are 5 BMAL1 binding sites in the TGF-β1promoter region, and BMAL1 can directly bind to the TGF-β1promoter region, which can inhibit the transcriptional activity of TGF-β1. Overexpression of BMAL1 inhibits TGF-β1/Smads pathway activity. Under the induction of recombinant human TGF-β1, the proliferation ability of NPC cells was enhanced, the activity of TGF-β1/Smads signaling pathway was enhanced, and nasopharyngeal cancer cells underwent EMT, and cell invasion and migration capacity increased. After overexpression of BMAL1, TGF-β1 no longer promotes TGF-β1/Smads signaling pathway activity, EMT is inhibited, and cell invasion and migration ability is weakened. BMAL1 combined with TGF-β1 has certain diagnostic value in predicting whether nasopharyngeal carcinoma metastasis. Conclusions: BMAL1 expression is downregulated in nasopharyngeal carcinoma, and its expression level is related to the development and metastasis of nasopharyngeal carcinoma. BMAL1 can inhibit the proliferation, epithelial-mesenchymal transformation and invasion and metastasis ability of NPC cells, and its mechanism is related to the inhibition of TGF-β1/Smads signaling pathway activity. It is speculated that it may become a new prognostic marker and therapeutic target for nasopharyngeal carcinoma.