STIM1-regulated exosomal EBV-LMP1 empowers endothelial cells with an aggressive phenotype by activating the Akt/ERK pathway in nasopharyngeal carcinoma

Abstract

Background Stromal interaction molecule 1 (STIM1)-mediated Ca 2+ signaling regulates tumor angiogenesis in nasopharyngeal carcinoma (NPC), an Epstein-Barr virus (EBV)-related human malignancy. However, the mechanism by which STIM1 modulates the endothelial functional phenotypes contributing to tumor angiogenesis remains elusive.Methods We explored the intercellular communication via exosomal biomolecules released by EBVinfected NPC cells and delivered to endothelial cells (ECs). The NPC cell-derived exosomes were isolated via differential centrifugation and observed with transmission electron microscopy. Exosome particle size was assessed by nanoparticle tracking analysis (NTA). Uptake of exosomes by recipient ECs was detected by uorescent labeling of the exosomes with PKH26. Tumor angiogenesis-associated pro les were characterized by determining cell proliferation, migration, tubulogenesis, and permeability in human umbilical vein endothelial cells (HUVECs). Activation of the Akt/ERK pathway was elucidated by detecting the phosphorylation level using western blotting. A chick embryo chorioallantoic membrane (CAM) xenograft model was employed to study tumor-associated neovascularization in vivo. Results The NPC cell-derived exosomes harboring EBV-encoded latent membrane protein 1 (LMP1) promoted proliferation, migration, tubulogenesis, and permeability by activating the Akt/ERK pathway in ECs. STIM1 silencing reduced LMP1 enrichment in NPC cell-derived exosomes, thereby reversing its prooncogenic effects in an Akt/ERK pathway-dependent manner. Furthermore, STIM1 knockdown in NPC cells blunted tumor-induced vascular network formation and inhibited intra-tumor neovascularization in the chorioallantoic membrane (CAM) xenograft model. Conclusion STIM1 regulates tumor angiogenesis by controlling exosomal EBV-LMP1 delivery to ECs in the NPC tumor microenvironment. Blocking exosome-mediated cell-to-cell horizontal transfer of EBVassociated oncogenic signaling molecules may be an effective therapeutic strategy for NPC.

Cancer Therapy Empowered by Extracellular Vesicle-Mediated Targeted Delivery

“…50) Additionally, inhibition of LMP1 transmitted by small EVs by silencing STIM1 in EBV-infected NPC cells partially eliminated the pro-angiogenic effect. 51) This suggests that tumor cells can manipulate the contents of EVs secreted by them, thus remodeling the tumor microenvironment. In the process of small EVs biosynthesis, production is mainly regulated by histocompatibility complex II (MCHC II), Syntenin, Syndecan, TSG101, synaptosomal-associated protein 23 (SNAP23) and RAB family proteins.…”

Suppression of Nasopharyngeal and Gastric Tumor Growth in a Mouse Model by Antibodies to Epstein–Barr Virus LMP1 Protein

“…According to recent research, LMP1, combined with exosomes, is abundantly released into the serum and saliva of NPC patients [ 3 ]. When isolated from NPC patient sera, LMP1/exosome complexes demonstrated a significant mitogenic response on cultured cells [ 4 ]. This suggests a role in tumor development via paracrine/exocrine action.…”