Sema4C Induces the Endothelial-Mesenchymal Transition of Tumor-Associated Lymphatic Endothelial Cells in Cervical Cancer via the ERK Pathway

Background: The endothelial-mesenchymal transition (EndMT) is a process that increases the promigratory abilities of endothelial cells (ECs). Although lymphatic endothelial cells (LECs) plays a positive role in tumor lymphatic metastasis, the regulation of LECs undergoing EndMT remains poorly understood. Previous study indicated that Semaphorin 4C (Sema4C) could be a marker of LECs in cervical cancer. Here, we try to understand the mechanism that Sema4C could promote LECs to get mesenchymal characters and enhance lymphatic metastasis in cervical cancer. Methods: The co-location of Sema4C and lymphatic marker LYVE1 was verified by confocal laser scanning. Primary tumor-associated LECs (TLECs) were distinguished from cervical cancer by flow cytometry from a mouse xenograft cervical tumor model. The promigratory ability was assessed using the Transwell test. Lentivirus infection was used to alter the expression of Sema4C in TLECs and the infection efficiency was tested by confocal laser scanning. The phospho-extracellular signal-regulated kinase (p-ERK) signaling pathway was measured using the ERK inhibitor (PD98059) ,as well as quantitative PCR and Western blot analysis. Results: Sema4C and LYVE1 co-located on TLECs. Primary TLECs were successfully separated and cultured. Overexpressing Sema4C by lentivirus infection stimulated the invasive capacity of TLECs and downregulated E-cadherin, whereas knocking down Sema4C had the opposite effects. TLECs pro-migratory ability was found to depend on the extracellular signal-regulated kinase (ERK) signaling pathway, as the ERK inhibitor (PD98059) reversed Sema4C-induced E-cadherin expression and migration ability. Conclusion: The results of this study suggest that the Sema4C-ERK-E-cadherin pathway appears to be critical for the EndMT of TLECs, which might promote lymph node metastasis. Thus, Sema4C could be a promising target for the treatment of cervical cancer with lymphatic metastasis.