Investigation Of Molecular Mechanism Of Vasculogenic Mimicry In Ovarian Carcinoma

Ovarian carcinoma is one of the common cancer diagnosis in females.It's morbidity ranks as the third most common genital tract cancer,and the death rate occupies the first place in gynecology malignant tumor.It has been verificated that the growth and spread of tumors depend,in part,on the formation of adequate vascular supply.The traditional theory believe that vasculogenesis and angiogenesis are the two types of tumor blood vessel neogenesis.Angiogenesis is considered as the unique style that tumor acquired blood supply.The term,"vasculogenic mimicry" was derived from aggressive uveal melanoma microcirculation by Maniotis in 1999.Till now,the relationship between VM,the molecular mechanism of VM formation and the prognosis is still not clear.In this study,the clinicopathological features of ovarian carcinomas with human Paraffin-embedded tumor tissue samples,combining the aggressive human ovarian carcinoma cell lines-SKOV-3 and OVCAR-3,were used to provide the experimental evidence of VEGF-a's functions in invasion,metastasis and VM formation of ovarian carcinoma,and the effections of VEGF-a on EphA2/MMPs signaling pathway in VM formation.The details of the investigation were as follows:The relationship between microcirculation pattern and clinicopathological features in ovarian carcinoma,the microcirculation patterns of most tumors includes endothelial dependent vessel,mosaic blood vessel and vasculogenic mimicry were observed in ovarian carcinoma too.84 ovarian carcinoma samples were divided into 2 groups according to if they have VM structure.VM was detected in 36 ovarian cancers from the patients.The formation of VM is close-related with FIGO stage, metastasis,histological types and pathological grades,however,unrelated with the age of patients,tumor sizes and ascites situation in ovarian carcinomas.Kaplan-Meier survival analysis was performed in this study,the results indicated that the prognosis for patients with VM was significantly worse than that of patients without VM.Invasion,migration,VM formation ability,and VM related signaling molecules expression after the ovarian carcinoma cell lines were treated by different cytokines. The invasion and migration activity enhanced by VEGF-a stimulation. Three-dimensional culture results demonstrate that both SKOV-3 and OVCAR-3 cells, when stimulated by VEGF-a,formed typical pipe-like structures after cultured within the three-dimensional Matrigel medium for 5 and 10 days.The mRNA and protein levels of EphA2 and VE-cadherin was significantly higher in VEGF-a group than that of the other groups,the activities of MMP-2 and MMP-9 were significant higher in VEGF-a group compared with those in other groups.Effections of VEGF-a on EphA2/MMPs signaling pathway in VM formation of ovarian carcinoma.Real-time PCR and Western blot results showed a down-regulation of EphA2 mRNA and protein levelsand also significant decreased VM formation in the 3D cultures after EphA2 knocking down,whereas there was no significant changing in VE-cadherin expression.Although transfected with siRNA targeting EphA2,the mRNA and protein expressions of EphA2 still up-regulated in S+ group compared with that in S-group(P＜0.05).The VE-candherin expressions were significant higher in N+ and S+ groups compared with N- and S- group respectively.Gelatin zymography shown there was a down-regulation of MMP-9 and MMP-2 expressions and activities in S+/S- groups,respectively.In conclusion,the microcirculation patterns include endothelial dependent vessel, mosaic blood vessel and vasculogenic mimicry were observed in ovarian carcinoma in present study.Clinical analysis has shown that the capacity for VM formation is stronger,and the more aggressive the tumor is,the poorer the prognosis for ovarian carcinoma patients.The ability of VM formation in ovarian carcinoma is related with histological grades,and the poorer the differentiation the tumor is,the stronger the capability of VM formation.It suggests that the effections of VEGF-a on EphA2/MMPs is the main pathway for VM formation based on EphA2-siRNA interference.VM-targeting strategies maybe have significant value in laying the foundation for a more explicit anti-tumor angiogenesis therapy.