The Mechanism Of LARS2 Regulating ABCA1 Induced Reprogramming Of Lipid Metabolism In Clear Cell Renal Cell Carcinoma

OBJECTIVE:Clear cell renal cell carcinoma(ccRCC),with accumulation of lipids in cytoplasm,is characterized as lipids metabolism reprogramming.Our previous study has detected the mutation of mitochondrial leucyl-tRNA synthetase 2(LARS2)by a whole genome sequencing of ccRCC tumor tissues.However,its function in metabolism reprogramming still remain unknown.The study aims at confirming the expression of the key gene ATP-binding cassette,sub-family A1(ABCA1)which is discovered through lipidomics analysis in lipid metabolism reprogramming of ccRCC.Further researches are then conducted to further explore the possible mechanism of LARS2 regulating ABCA1 in induction of reprogramming process,providing potential value in research of ccRCC tumorigenesis.METHOD:(1)Oil red staining were used on both tumor tissues and compared adjacent normal tissues.(2)LARS2 overexpression cell line and its compared cell line,alone with LARS2 low-expression cell line and its compare cell line were underwent lipid metabolomic analysis to detect the significant lipids of which is cholesterol ester(ChE).Then 30 samples of tumor tissues and compared adjacent normal tissues were analyzed to further confirm.Key enzyme gene ABCA1 that regulated the ChE was found by the method of bioinformatics tools,according to lipidomics analysis.(3)The qT-PCR was used to confirm the expression of LARS2 and ABCA1 in another 90 couples of tumor and normal tissues,as well in above four cell lines.Then test kits were used to test the concentration of ChE among 90 couples of tumor tissues,compared normal tissues and four cell lines.Results were divided into two groups based on the expression level of LARS2,then the expression level of ABCA1 and concentration of ChE were analyzed to explore the regulating mechanism.RESULTS:ccRCC abound lipids thus emerge obvious staining.Lipidomics analysis overall detected more than 1000 species changing of lipids,revealing that ccRCC lipid metabolism reprogramming occurs.Lipidomics analysis detected accumulation of ChE within tumor tissues and ccRCC cell lines.According to bioinformatics,ATP-binding cassette,sub-family A1(ABCA1)servs as main regulator of ChE formation.LARS2,as an antioncogene,is deactivated in ccRCC and in its overexpression cancer cell line decreased expression of ABCA1 can be measured which is related to the reduction of cholesterol ester.Tumor tissues which relatively expressed higher LARS2 had significant reduction of ABCA1 expression and cholesterol ester concentration.Conclusion:The main character of ccRCC lipid metabolism reprogramming is ChE accumulation.ABCA1 is responsible for regulation of ChE metabolism and its excessive expression can induce ChE abundance.LARS2 overexpression cancer cell line had a lower expression of ABCA1 and ChE concentration than its compared cell line low-expression LARS2 cell line.In tumor tissues,a lower expression of LARS2 was related to higher expression of ABCA1 and increased level of ChE,suggesting that the deactivation of LARS2 may play important role in inducing up-regulation of ABCA1 which then trigger the lipid metabolism reprogramming in ccRCC.