The cross-talk between endothelial cell-specific molecule 1 and long non-coding RNAs HULC and H19 through HIF/VEGF pathway

Purpose. The aim of this study is to elucidate the potential role of endothelial cell-specific molecule 1 (ESM-1) in tumor progression by evaluating the effect of ESM-1 silencing on HIF/VEGF pathway in non-small-cell lung carcinoma (NSCLC). Furthermore, the cross-talk between ESM-1 and selected lncRNAs was investigated. Methods. The A549 cells were transfected with ESM-1 siRNA and cells were treated with deferoxamine to simulate the hypoxic conditions. mRNA levels of ESM-1, VEGFR-2, HIF-1α, lncRNAs HULC and H19 were evaluated by qPCR; protein levels of ESM-1,VEGFR-2 and AKT were assayed by ELISA and WB, respectively; cell migration and proliferation were evaluated by scratch assay and MTT, respectively. Results. The hypoxia enhanced the expression levels of ESM-1, VEGFR-2, HIF-1α, HULC and H19, whereas the silencing of ESM-1 decreased mRNA and protein levels of VEGFR-2, AKT and both lncRNAs. Furthermore, ESM-1 silencing reduced cell migration and proliferation. Discussion. ESM-1 is a proteoglycan considered as a potential biomarker in inflammatory disorders and tumor progression [1]. In hypoxic conditions, the upregulation of HIF-1α stimulates the VEGF pathway, which is a positive regulator of ESM-1 in angiogenesis. HULC and H19 are angiogenesis-related lncRNAs influencing HIF/VEGF pathway [2]. Our data demonstrated that ESM-1 silencing reduce mRNA and protein levels of VEGFR-2 and AKT, indicating the modulatory effect of ESM-1 in HIF/VEGF pathway, with a consequent decrease in cell migration and proliferation. Notably, ESM-1 knockdown reduced HULC and H19 expression, demonstrating a regulatory mechanism that could affect tumor angiogenesis. Conclusion. In this context, ESM-1 seems to play a role in the activation of HIF/VEGF pathway also through the modulation of HULC and H19.