ABSTRACT
During the uric acid production, excretion and reabsorption in the liver, kidney and intestine, several uric acid transporter proteins are involved in these processes. A large number of studies have shown that glucose transporter 9 plays an important role in the uric acid transport in the liver, kidney and intestine, and participates in the uric acid reabsorption. The ATP-binding cassette superfamily G member 2 is mainly expressed in the apical membrane of the proximal tubular epithelial cells of the kidney, which is involved in the uric acid secretion. The multidrug resistant protein 4 is expressed in the apical membrane of the renal tubular epithelial cells, which transfers uric acid from the renal tubular epithelial cells into the renal tubular lumen. The urate-anion transporter 1 as well as the organic anion transporters 1 and 3 are all the organic anion transporters belonging to the SLC22 A family of transmembrane transporters, and all participate in the uric acid transport in the kidney, especially the uric acid secretion and excretion. In this review, we summarize the research progress of these uric acid transporters, focusing on their effects on the regulation of the serum uric acid balance.
ABSTRACT
Objective To investigate the relationship between the expression of linc-VLDLR in extracellular vesicles (EVs) and the development and drug resistance of esophageal carcinoma.Methods Fifty percent of inhibitory concentration (ICs0) ofadriamycin (ADM) for Eca109 cells was detected by MTT assay,after the treatment of esophageal squamous cell carcinoma Eca109 cell line with different concentrations of ADM for 24h.The culture medium was treated with 3 concentrations of ADM based on the IC50 for 24h for extracting EVs in Eca109 cells.linc-VLDLR mRNA expression in EVs was detected by qRT-PCR assay.ICs0 of ADM for Eca109 cells intervened by EVs for 48h was detected by MTT assay.Cell cycle was detected by FCM and linc-VLDLR and ABCG2mRNA expressions in Eca109 cells were detected by qRT-PCR after the treatment of the EVs for 48h.Results ICs0 of ADM acting on Eca109 cells for 24h was 0.44 ± 0.02μg/ml,so ADM concentrations of 0.2,0.4,0.8μg/ml were choosed in the following studies.EVs were extracted from the supernatant after the treatment of 0,0.2,0.4,0.8μg/ml ADM for 24h and were labeled as EVs1,2,3 and 4 respectively.LincVLDLR mRNA expression in EVs4 was significantly higher than that in EVs1-3 (P＜0.01).ADM ICs0 for Eca109 cells in EVs4 group was significantly higher than that in other groups after the treatment of EVs1-4 on Eca109 cells for 48h (P＜0.05).Flow cytometry results showed that the proliferation index of Eca109 cells in EVs4 group was significantly higher than that in EVs 1-3 and control groups (P＜0.01).Linc-VLDLR and ABCG2 mRNA expression levels in Eca109 cells of EVs4 group were significantly higher than these of EVs1-3 and control groups (P＜0.05).Conclusions High expression of linc-VLDLR and ABCG2 gene in esophageal cancer cells is involved in the formation of esophageal cancer resistance.EVs released by drug-resistant cells can upregulate the expression of ABCG2 in esophageal cancer cells and regulate the drug resistance of esophageal cancer cells,which is related to the linc-VLDLR gene carried by EVs.