| Background:Renal cell carcinoma is one of the most common urological malignancies in China.the incidence and mortality of RCC have been a rising trend.Surgical resection is mainly the treatment of early kidney cancer.But tumor recurrence or distant metastasis is observed among about 30% of postoperation patients soon.metastatic renal cell carcinoma develops severely resistance and adverse effects to radiotherapy,chemotherapy and cytokine therapy,having a poor clinical prognosis.These have greatly attracted the interest of scientists in the fields of kidney cancer basic and translational research.In recent 10 years small molecule vascular targeting agents consisting mainly of sorafenib benefit metastatic renal cell carcinoma.However,the objective drug response rate is very low,and the drug resistance easily happened,the probability of drug resistance is 100% after several treatment courses.With considering the side effects and high cost of drugs,the clinical application prospects of vascular targeting agents is not optimistic,So the researchers need to conduct a comprehensive and thorough study on the molecular biology mechanism about occurrence and advance of kidney cancer,in order to seeking novel kidney cancer treatment targets.Many studies confirm that the tumor cells acquire the reprogramming of their metabolic pathway in order to meet the energy and material demand of abnormal proliferation.Metabolism reprogramming is characterized by aerobic glycolysis and enhanced lipid synthesis.The latter characteristic is particularly shown clearly on the kidney cancer.Including Fatty acid synthase(fatty acid synthase,FASN),multiple genes regulating the lipid metabolism are closely related to the kidney cancer and participate in the tumorigenesis and progression.Fatty acid binding protein 7(fatty acid binding protein 7,FABP-7)belongs to the family of intracellular fatty acid binding protein,the study found that FABP-7 have many functions including fatty acid intaking and intracellular transporting and metabolism function,and could combine and dissolve long-chain polyunsaturated fatty acids and regulate intracellular lipid metabolic balance.A large body of evidences have shown that high FABP7 expression in kidney cancer is associated with poor prognosis.However,the role of FABP7 on kidney lipid metabolism and related mechanism has not been reported so far.Objective:The present study is aimed to investigate the potential roles of the FABP7 in lipid metabolism and tumor cell growth of kidney cancer.Methods:Real-time PCR was used to detect the expression of FABP7 mRNA in human normal kidney cell HK-2 and RCC cell OSRC-2,769-P,786-O and ACHN.The empty plasmid(VC)and FABP7 expression plasmid(FABP7)are transfected into RCC cell which endogenous FABP7 expression level is low.The stable transfection cell line is selected by G418.Western blot was performed to determine transfection effect.We used nude mice to establish subcutaneous xenograft model of FABP7 high expression and empty plasmid and observed the tumor growth.Oil red O staining was used to measure the lipid amount of the frozen sections which were made of subcutaneous tumor tissue.Immunohistochemistry was performed to detect the expression of FABP7 and FASN protein in 62 cases of kidney cancer tissues,and Pearson correlation was employed to analyze the associations between genes.When the empty plasmid(VC)and FABP7 expression plasmid(FABP7)were transfected into OSRC-2 cell,Real-time PCR was used to detect the expression of FASN mRNA again in order to further analyze the correlations between genes.when specific siRNA targeting FASN were co-transfected into cells with FABP7 over-expression plasmid,the FASN mRNA expression was again determined.MTT assay were performed to determine the growth ability of three groups of stable transfection cells in vitro.Results:FABP7 mRNA expression level is different in variety of cells(P < 0.01),the expression in all kinds of RCC cells are higher than normal HK-2 cell(P < 0.05),the expression in OSRC-2 cell is the lowest among various RCC cells(P < 0.05).The findings of western blot confirmed the stripe grey value in FABP7 over-expression group is higher than the VC group(P < 0.01).The results of animal experiments showed that nude mice subcutaneous tumors in FABP7 group had larger volume and heavier weight than VC group,(P < 0.001).The Oil red O staining results showed dyeing area of FABP7 group is larger than the VC group(P < 0.01).The expression of FASN mRNA in FABP7 group was higher than VC group(P < 0.001).MTT experiment results found the RCC growth ability of FABP7 is more stronger than VC group(P < 0.001).when siFASN was co-transfected into cells with FABP7 over-expression plasmid,the growth ability of cells was ablated(P < 0.01).Conclusion:The over-expression of FABP7 promotes the growth of RCC cells and lipid synthesis.The expression of FABP7 in human RCC tissues were positively correlated with FASN.FABP7 positively regulates the expression of key genes(FASN)participating in lipid metabolism,FASN gene plays crucial roles in FABP7 mediated growth of RCC in vitro. |
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