Calreticulin Promotes Migration and Invasion of Esophageal Cancer Cells by Upregulating Neuropilin-1 Expression via STAT5A

Purpose: We previously revealed that the calreticulin (CRT) gene is a candidate oncogene promoting cell migration and invasion and that neuropilin-1 (NRP1) is a possible effector downstream of CRT in esophageal squamous carcinoma cells. This study aims to explore the mechanisms underlying the migration and invasion of esophageal cancer cells regulated by CRT through NRP1. Experimental Design: Quantitative reverse-transcription polymerase chain reaction, Western blot analysis, chromatin immunoprecipitation, and reporter gene assays were used to investigate the relationship between CRT and NRP1. In vitro and in vivo assays were carried out to evaluate the effects of NRP1 on malignant phenotypes of ESCC cells and tumor metastasis in NOD/SCID mice. Immunohistochemistry was performed to analyze the expression of CRT and NRP1 in esophageal squamous cell carcinomas (ESCC). Results: Knockdown of CRT decreased the expression of NRP1. Inhibition of NRP1 reduced ESCC cell motility in vitro and experimental metastasis in vivo. Ectopic expression of NRP1 rescued the defects of cell migration and invasion in CRT-shRNA cells. CRT depletion inhibited STAT5A phosphorylation at the Y694 site via a CaMKII-independent pathway. Moreover, STAT5A directly regulated NRP1 transcription. Knockdown of CRT or NRP1 led to a downregulation of MMP2, MMP9, and FAK. Notably, positive correlation was found between CRT and NRP1 expression in ESCC tissues (P = 5.87 x 10(-5)). CRT and NRP1 coexpression was significantly associated with lymph node metastasis (P = 0.025). Conclusions: Our findings suggest that NRP1 is a critical downstream effector of CRT in promoting cell migration and invasion, which might contribute to the metastasis of ESCC.