CLDN1 induces autophagy to promote proliferation and metastasis of esophageal squamous carcinoma through AMPK/STAT1/ULK1 signaling

Tight junction is a structural constitution in cell-cell adhesion and play an important role in the maintenance of permeability and integrity of normal epithelial cell barrier. The protein encoded by Claudin 1 (CLDN1), a member of the claudin family, is an integral membrane protein and a component of tight junction strands. CLDN1 has been proved to regulate the proliferation and metastasis of multiple tumors, but little is known about its role in esophageal squamous cell carcinoma (ESCC). Here, we found that CLDN1 was aberrantly increased in ESCC tissues and cell lines, and mainly distributed in the nucleus of tumor cells. Furthermore, we confirmed that CLDN1 promoted the proliferation and metastasis of ESCC by triggering autophagy both in vitro and in vivo. Mechanically, we validated that CLDN1-induced autophagy via increasing Unc-51 like autophagy activating kinase 1 (ULK1) expression through AMP-activated protein kinase (AMPK)/signal transducer and activator of transcription 1 (STAT1) signaling pathway in ESCC cells. Taken together, our findings demonstrated that aberrant expression and distribution of CLDN1 promoted the proliferation and metastasis of esophageal squamous carcinoma by triggering autophagy through AMPK/STAT1/ULK1 signaling pathway.