A Role Of EBV In Angiogenesis And Vascular Mimicry Of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma(NPC)is one of the most common head and neck cancers in south China and southeast Asia.The distribution of NPC is region-specific and race-specific,and the carcinogenesis of nasopharynx is strongly associated with EBV infection.Most patients with the disease are diagnosed only when the tumor has reached an advanced stage(stages ? and ?).Therefore,effective treatment is very important to improve the survival of patients.At present,the main treatment of NPC is radiation therapy,and based on its highly vascularized feature,anti-vascular therapy has also been applied and proved effective in treating NPC.The anti-proliferative and anti-vascular agent Cetuximab has been approved by FDA for treating advanced NPC.However,not all patients would benefit from such treatment because of the drug resistance.Therefore,exploring the molecular mechanism underlying NPC angiogenesis is essential to developing more effective anti-vascular agents for NPC treatment.Epstein-Barr virus(EBV)infection is a critical etiological factor in NPC.EBV-encoded proteins,such as LMP1 and EBNA1,can induce multiple oncogenic properties,including tumor angiogenesis,to promote NPC development.Studying the regulatory network of EBV in tumor angiogenesis is helpful for elucidating the mechanism of NPC angiogenesis and the role of EBV infection in tumor progression.In this study,based on the successful EBV infection of NPC cells,we first confirmed that EBV infection promoted tumor angiogenesis and growth.We further validated the role of EBV by CRISPR/Cas9-mediated elimination of EBV Next,via the proteomics analysis,we found that EBV increased a number of angiogenic factors secretion,including CCL5.We then studied the function of CCL5 and proved that CCL5 was a key mediator of EBV-induced angiogenesis.To determine the specific mechanisms underlying CCL5-mediated angiogenesis,we compared the transcriptome between EBV-infected and EBV-uninfected cells and found that EBV activated PI3K/AKT signaling pathway.Subsequent study confirmed the activation of PI3K/AKT pathway and indicated that HIF-1? was also activated by EBV Furthermore,we proved that CCL5 regulated the PI3K/AKT and HIF-la pathways to promote tumor angiogenesis.Finally,we determined the correlation between CCL5 and tumor angiogenesis in human NPC samples.Taken together,our study suggests that EBV infection induces the production of CCL5,which promotes NPC angiogenesis by enhancing the PI3K/AKT and HEF-1?pathways.Tumors require a large amount of blood supply to maintain rapid growth and metastasis.A lot of researches have focused on tumor angiogenesis,in which blood vessels are formed in and around tumors by the endothelial cells in tumor microenvironment.However,recent studies showed that the blood circulation in tumors is not just through canonical blood vessels to support tumor growth.In tumor tissues,some lumen-like structures called vasculogenic mimicry(VM)can be formed by tumor cells to mediate the blood circulation,which is surrounded by a basement membrane and can be stained by PAS.Vasculogenic mimicry is another way of blood circulation in tumors,independent of the canonical blood vessels.Vasculogenic mimicry has been studied in some tumors such as melanoma,prostate cancer and hepatoma,in which it plays an important role in tumor development.There are few studies on vasculogenic mimicry in nasopharyngeal carcinoma(NPC).NPC is a malignancy strongly associated with EBV.Our previous study has showed that EBV promotes NPC angiogenesis.Whether EBV regulates the vasculogenic mimicry remains elusive.In this study,we proved that EBV infection promoted vasculogenic mimicry formation and tumor development of nasopharyngeal carcinoma cells by using EBV-infected NPC cells and CRISPR/Cas9-mediated EBV reduction.Subsequent studies suggested that HIF-la was activated in EBV-infected cells and mediated EBV-induced vasculogenic mimicry.Furthermore,we proved that the PI3K/AKT pathway was also involved in the EBV-induced vasculogenic mimicry by modulating HEF-Ia?Collectively,EBV can induce the formation of vasculogenic mimicry in nasopharyngeal carcinoma via activating the AKT/HOIF-1? pathway and promote tumor development.