The Role And Regulation Mechanism Of Adrenomedullin(ADM) On 786-0 Renal Cell Carcinoma With Transplantation Tumor In Nude Mice By Extracellular Signal-regulated Protein Kinase(ERK1/2) Signaling Pathway

Objective: Renel tumor is an comman malignant tumor of urinary system, its incidence rate was increased by 6.5% per year. It accounts for 80%-90% in renal malignant tumor, and its fatality rate was the highest in urinary system related tumor. ADM is a peptide isolated from pheochromocytoma, study found that ADM was high expressed in many tumor, and was related to proliferation, invasion and metastasis of tumor. We studied the effect and mechanism of ADM on the growth of tumor, and explored the role and regulation mechanism of adrenomedullin(ADM) on 786-0 renal cell carcinoma with transplantation tumor in nude mice by extracellular signal-regulated protein kinase(ERK1/2) signaling pathway.Methods: Nude mouse models transplanted human 786-0 renal tumor cells to the subcutaeous of mouses were divided into four group depended on the different interventions, which was control group, ADM group, ADM22-52 group, PD98059 group, respectively. We recorded the tumor formation rates and measured the size of tumor, observed the pathology changes by HE staining, detected the protein expression of PCNA, p-ERK1/2 and VEGF-A by immunohistochemisty, analyzed the protein expression of ADM receptor, p-ERK1/2 and VEGF-A by western blotting.Results: Tumor node was observed at the inoculation site after 3 days. Total 35 nude mouses were transplanted human 786-0 renal tumor cells to the subcutaeous, 1 mouse was dead, tumor formation rate was 87.5%(35/40). After 2 weeks, 32 nude mouses were divided into four group depended on the different interventions, which was control group, ADM group, ADM22-52 group, PD98059 group, respectively, and the initiate tumor size of four group had no differennce(P > 0.05). HE staining sections showed that transplantation tumor was characterized by clear renal cell carcinoma infiltrating adenocarcinoma. Compared wirh control and ADM group, there were more necrosis areas in ADM22-52 group and PD98059 group. Immunohistochemisty showed that the expression of PCNA 、 p-ERKand VEGF-A in ADM group were higher than contorl group by 1.61 times, 1.35 times and 1.43 times respectively. The expression of PCNA were lower with 8.89% and 35.56% by ADM group respectively in ADM22-52 and PD98059 group. The expression of p-ERK1/2 were lower with 8% and 36% by ADM group respectively in ADM22-52 and PD98059 group(all P<0.05). Western blotting showed that the protein expression of ADM receptor, p-ERK1/2 and VEGF-A in ADM group was higher than control group by 1.27 times, 1.41 times and 1.45 time, respectively. However, above three proteins in ADM22-52 group were lower with 21.43%,50.00% and 17.65% by ADM group, likewise, lower with 42.86%, 31.11% and 41.18% by ADM group in PD98059 group(all P<0.05).Conclusions: As a new vasoactive peptide, renel tumor cell is the target cell of ADM, it can regulate cell mitosis, blood vessel generation of tumor, cell apoptosis and promote the development of tumor by autocrine and paracrine secretion. ADM is promising to be the target of renel tumor therapy, through blocking ADM receptor and ERK1/2 signaling pathway that partially or entirely blocking the effect of ADM on tumor. It can provide a molecular biology marker for the studying of renel tumor invasion, metastasis, prognosis and tumor staging, while provide some evidences for the renel cell tumor combined modality therapy, especially gene targeting therapy, through detecting the expression level of ADM.