| Renal cell carcinoma(RCC)is one of the most common cancer in urologic tumors.The most common histological type,clear cell renal carcinoma(cc RCC)represents 75-85% of all RCCs,which is characteristically hypervascular.Angiogenesis is closely related to the prognosis and progression of cc RCC,so anti-angiogenic targeted therapy has gradually become an important treatment for advanced RCC.However,as the current anti-angiogenic therapy targeting vascular endothelial growth factor(VEGF)is not completely satisfactory due to its inherent defects,the identification of new targets has become a popular research focus.Tumor angiogenesis is required for tumor growth and metastasis,and the Ang/Tie2 axis plays a pivotal role in angiogenesis.As an angiogenin receptor,Tie2 is mainly expressed by endothelial cells;some macrophages and monocytes can also express Tie2,namely,Tie2-expressing monocytes(TEMs).More and more studies have found that TEMs play a unique role in tumor angiogenesis.B7-H3,a new member of the B7 family of co-stimulatory molecules,has a critical function in the T cell-mediated anti-tumor immune response,B7-H3 is specifically expressed at high levels in the vascular endothelium of various malignant tumor tissues,and B7-H3 expression is frequently associated with a poor prognosis.However,the relationship between B7-H3 and the angiogenesis of cc RCC remains unclear.The purpose of this study was to investigate the expression and significance of B7-H3 and Tie2 in the vasculature of cc RCC and explore their roles in angiogenesis of cc RCC.Part ? Expression and significance of B7-H3 and Tie2 in the tumor vasculature of clear cell renal carcinomaObjective: To detect the expression of B7-H3 and Tie2 in cc RCC,analyze their relationship with clinicopathological characteristics of cc RCC,elucidate their prognostic significance in cc RCC,and preliminarily explore their roles in angiogenesis of cc RCC.Methods: 1.In this study,we used immunohistochemical(IHC)methods to detect tumor vascular expression of B7-H3 and Tie2 in tissue microarrays of 82 cc RCC patient samples and 20 cases of adjacent normal tissues.2.Immunofluorescence(IF)and laser scanning confocal microscopy(LSCM)methods were applied to study the expression and localization of B7-H3 and Tie2 in the vascular endothelial cells of cc RCC.Results: 1.The expression of B7-H3 in the vasculature of cc RCC was significantly higher than that of normal tissues(P<0.001).The vascular expression of B7-H3 was associated with the cc RCC nuclear grade(P=0.008),T stage(P=0.012),lympy node metasis(P=0.018),distant metastasis(P=0.048)and tumor-node-metastasis(TNM)stage(P=0.021).2.The expression of Tie2 in the vasculature of cc RCC was significantly higher than that of normal tissues(P=0.007).The vascular expression of Tie2 was significantly correlated with T stage(P=0.001),lympy node metasis(P=0.010)and TNM stage(P=0.005),but it was not related to cc RCC nuclear grade(P=0.249)or distant metastasis(P=0.459);Expression of B7-H3 and Tie2 was positively correlated(P<0.05).3.The microvessel density(MVD)labeled by CD34 was significantly correlated with tumor nuclear grade(P=0.032),T stage(P=0.004),lympy node metasis(P=0.007),distant metastasis(P=0.002)and TNM stage(P<0.001).The vascular expression of B7-H3 and Tie2 were both positively correlated with MVD.4.IF and LSCM showed that both B7-H3 and Tie2 were localized and co-expressed in tumor vascular endothelial cells of cc RCC.Conclusions: 1.The expression of B7-H3 and Tie2 in cc RCC was closely related to the progression and prognosis of the disease,and they can serve as effective endothelial markers for the prognosis of cc RCC.2.B7-H3 and Tie2 may have synergistic effects on angiogenesis of cc RCC,and they were expected to become a promising target of anti-angiogenic targeted therapy for cc RCC.Part ? Experimental studies on angiogenesis mediated by B7-H3~+TEMs in cc RCCObjective: To explore the role of B7-H3~+TEMs in angiogenesis of ccRCC.Methods: 1.Level of B7-H3 expression on TEMs was detected by flow cytometry(FCM)in cc RCC tissues and normal renal tissues.2.The level of CD34 was detected by IHC,and the difference of MVD between high B7-H3~+TEMs group and low B7-H3~+TEMs group in cc RCC was analyzed.3.B7-H3~+TEMs or B7-H3~-TEMs was co-cultured with the 786-O cell lines,and B7-H3~+TEMs or B7-H3~-TEMs culture supernatant was collected as conditioned medium,then the effect of B7-H3~+TEMs on tubule formation of human umbilical vein endothelial cells(HUVECs)was tested by tubule formation assay.4.The conditioned medium was acted on the aortic rings of mouse,and the effect of B7-H3+TEMs on the formation of neovascularization of the aortic rings was tested by mouse aortic ring assay.Results: 1.FCM showed that the frequency of B7-H3 expression on TEMs in cc RCC was(45.10 ± 17.78)%,and the frequency of B7-H3 expression in normal kidney tissues was(10.28 ± 4.28)%.The frequency of B7-H3 expression on TEMs was significantly higher than that in normal renal tissues(P<0.001).2.MVD in low B7-H3~+TEMs group was 76.55 ± 20.80,MVD in high B7-H3~+TEMs group was 103.81 ± 29.28;the MVD of high B7-H3~+TEMs group was significantly higher than that of low B7-H3~+TEMs group(P=0.027).3.The results of tube formation assay showed that the ability of tubule formation of HUVECs in B7-H3~+TEMs group was significantly stronger than that of B7-H3~-TEMs group and blank control group(P<0.001).4.The results of mouse aortic ring assay showed that the ability of neovascularization of mouse aortic ring in B7-H3~+TEMs group was significantly higher than that of B7-H3-TEMs group and blank control group(P<0.001).Conclusions: B7-H3~+TEMs can promote angiogenesis in cc RCC.B7-H3~+TEMsmight act as an effective target in anti-angiogenic therapy for ccRCC. |
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