Aberrant Expression of FGFRL1 in Esophageal Cancer and Its Regulation by miR-107

BACKGROUND: Fibroblast growth factor receptors are growth factor receptor tyrosine kinases, exerting their roles in embryogenesis, tissue homeostasis, and development of cancer. However, little is known about the expression and function of FGFRL1 in esophageal cancer (EC). METHODS: We systematically evaluated the expression of FGFRL1 in TCGA and GETex datasets followed by expression analysis in EC cell lines and clinical specimens using immunofluorescence (IF) and immunohistochemistry (IHC) respectively. RESULTS: GEPIA analysis on TCGA and GETex datasets identified significant upregulation of FGFRL1 in EC patients (n=182) compared to normal controls (n=286, p<0.05). IHC analysis showed significantly higher FGFRL1 expression in EC tissues as compared to the distant matched non-malignant tissues (p<0.001). Immunoflourescence in EC cells suggested increased expression of FGFRL1 from WDSCC (KYSE30) to MDSCC (KYSE140) and finally to PDSCC (KYSE410). In-silico tools predicted miR-107 as most significant miRNA regulating FGFRL1 expression. qRT-PCR revealed miR-107 expression to be significantly and inversely correlated with FGFRL1 expression in 73% (22/30) EC tissues (p=0.015) and over-expression of miR-107 resulted in significantly decreased expression of FGFRL1 at mRNA (fold change=0.11, p=0.0016) as well as protein level in miR-107 versus NC treated cells. Luciferase reporter assay using FGFRL1-3’UTR further confirmed it to be a direct target of miR-107. CONCLUSION: Our results herein document clinical as well as functional relevance of FGFRL1 in EC and its regulation by miR-107.