ApoC1 Promotes The Metastasis Of Clear Cell Renal Cell Carcinoma Via Activating STAT3

Objective:Kidney cancer is one of the 10 most common cancers,and which is usually not sensitive to chemotherapy.About 70%of patients with renal cell carcinoma belong to the renal clear cell carcinoma subtype,and metastasis occurs in about three-quarters of patients.Therefore,studying the mechanism of renal cancer metastasis and its molecular regulatory network will help to understand the mechanism of renal cancer metastasis and thus improve the therapeutic effect of renal cancer.Methods:Clinical database analysis to confirm the expression of ApoC1 in patients with renal cancer;Construction of high metastatic cell lines and parental cell lines to study the correlation between renal cancer metastasis and ApoC1;Real-Time PCR technology to study ApoC1 related signaling pathways expression of mRNA;ApoC1 was silenced by siRNA transfection;ApoC1 was highly expressed by viral transfection technology;Western blot was used to investigate the expression of ApoC1 and transfer-related proteins;Transwell and wound healing experiments were performed to investigate the ability of renal cancer cells to migrate and invade;SRB method studies proliferation of renal cancer cells;Co-immunoprecipitation technology to study the binding of ApoC1and STAT3;Nuclear separation method to observe the activation of STAT3 into the nucleus;Immunofluorescence experiments to observe the co-distribution of ApoC1 and STAT3 in and outside the nucleus;HUVEC cells and renal cancer cells Co-culture to study whether ApoC1 is related to angiogenesis;PET-CT technology to study tumor metastasis in nude mice.Result:(1)Correlation between ApoC1 expression and poor prognosis of renal clear cell carcinoma We found through Oncomine database mining that compared with normal tissues,ApoC1 showed high expression in tissues of patients with multiple tumors,especially in renal cancer patients.The results of UALCAN database showed that the expression of ApoC1 followed the progression of renal cancer is increasing,which suggests that the expression of ApoC1 is related to the occurrence and development of renal cancer.A search and analysis based on the TCGA database showed that patients with high expression of ApoC1 had significantly shorter survival than patients with low expression.It is suggested that ApoC1 is associated with poor prognosis of renal cancer.(2)ApoC1was related to metastasis of ccRCC cellsTranswell and wound healing experiments show that silencing ApoC1 could inhibit the migration and invasion of ccRCC cells,and at the same time inhibited the occurrence of EMT,which is manifested by increased expression of E-cadherin and decreased expression of N-cadherin.In contrast,the high expression of ApoC1 could promote the migration and invasion of ccRCC cells and induce the occurrence of EMT,which is manifested by a decrease in E-cadherin expression and an increase in N-cadherin expression.In vivo experiments in nude mice also confirmed that ApoC1 overexpressing ccRCC cells had significantly enhanced metastasis capacity compared to normal ccRCC cells,suggesting that ApoC1 is involved in the metastasis of renal cancer.(3)ApoC1 activated STAT3 and promotes ccRCC metastasisOil red staining of ccRCC cells revealed that ApoC1 promoted metastasis was not related to the lipid content in ccRCC cells.Next,by detecting the mRNA expression of ccRCC cell transfer-related signaling pathway proteins that overexpress ApoC1,it was found that overexpression of ApoC1 activates mRNA expression of STAT3 signaling pathway proteins,suggesting that STAT3 may participate in ApoC1-mediated ccRCC transfer.Western blot compared the effect of high and low expression of ApoC1 on STAT3activation,and found that ApoC1 increased the phosphorylation activation of STAT3.Similarly,ApoC1 could promote the nuclear entry of STAT3.Immunoprecipitation confirmed that ApoC1 and STAT3 would bind in ccRCC cells,and immunofluorescence demonstrated that ApoC1 and STAT3 co-localized.STAT3 inhibitors and STAT3 siRNA could reverse the ccRCC metastasis promoted by ApoC1.(4)ApoC1 promoted ccRCC metastasis via exosome secretionApoC1 could promote the migration and STAT3 activation in vascular endothelial cells.The co-culture experiments of ccRCC cells and HUVEC cells showed that ccRCC cells could secrete ApoC1 via exosomes to promote the migration ability of vascular endothelial cells and the activation of STAT3.(5)DPP-4 inhibition could reverse ccRCC metastasis promoted by ApoC1In fact that there was no effective inhibitor of ApoC1,and the literature reports that DPP-4 inhibition could reduce the expression of ApoC1,DPP-4 may be an effective target for intervention of ApoC1 expression.Our results show that DPP-4 inhibitors or knockouts could reverse ccRCC migration and STAT3 activation promoted by ApoC1.Conclusions: ApoC1 was abnormally highly expressed in renal cancer patient samples.ApoC1 could promote the metastatic capacity of ccRCC cells by binding and activating STAT3.CcRCC cells could secrete ApoC1 via exosomes to promote the migration of motor endothelial cells and the activation of STAT3.Intervention of DPP-4 inhibited ccRCC metastasis promoted by ApoC1.The ApoC1-STAT3 signaling pathway discovered in this study provides potential therapeutic targets and new intervention strategies for the treatment of renal cancer.