Objective: Aryl hydrocarbon receptor nuclear transporter-like 2 (ARNTL2) can bind to clock circadian regulator (CLOCK) to regulate gene expression and is abnormally expressed in various cancers. Nevertheless, its effects on esophageal cancer (ESCC) are unclear. This work can uncover the intriguing mechanism of ARNTL2 in ESCC.
Methods: Malignant phenotypes including cell proliferation, invasion, migration, and epithelial mesenchymal transition (EMT), were investigated. We established a BALB/c nude mouse (5-6 weeks) model with ESCC to verify the influence of ARNTL2/ANXA2/C-MYC axis. ESCC tissues (n = 100) and paired adjacent normal tissues (n = 100) from patients with ESCC were collected. The recruitment of ARNTL2 and CLOCK in ANXA2 promoter was studied by ChIP and dual-luciferase reporter assay. RIP and RNA pulldown were used to explore the relationship between ANXA2 and C-MYC mRNA.
Results: Compared to adjacent normal tissues, ESCC tissues developed the significant increase ARNTL2, ANXA2, and C-MYC. ARNTL2, which interacts with CLOCK, was recruited in ANXA2 promoter and elevated ANXA2. ARNTL2 silence reduced cell proliferation, migration and invasion and inhibited EMT, which was reversed by ANXA2 overexpression. ANXA2 can bind to the 3'UTR of C-MYC transcript; further assays confirmed that ANXA2 increased the protein abundance of C-MYC. ANXA2 knockdown resulted in a decrease in malignant phenotypes, whereas C-MYC overexpression reversed these changes. ARNTL2 silence inhibited the formation, growth and EMT of subcutaneous tumors and suppressed C-MYC; ANXA2 overexpression reversed these alterations.
Conclusion: ARNTL2 activated the transcription of ANXA2, which interacts with C-MYC transcript, promoting the development of malignant behaviors of ESCC cells.
Keywords: C-MYC; Esophageal cancer; annexin 2; aryl hydrocarbon receptor nuclear transporter-like 2.