Glycine suppresses kidney calcium oxalate crystal depositions via regulating urinary excretions of oxalate and citrate.

An abnormal urine composition is a key reason for kidney stone formation, but little is known about the roles of small metabolites in the urine during kidney stone formation. Here, we found urine glycine in patients with kidney calcium oxalate (CaOx) stone was significantly lower than that in healthy people via 1 H NMR spectra detection, and investigated the role and underlying mechanism of glycine in the regulation of CaOx stone formation. Our results showed that glycine could significantly attenuate ethylene glycol-induced CaOx crystal depositions in rat kidney via decreasing urine oxalate and increasing urine citrate. Mechanism studies revealed that glycine could decrease urine oxalate through downregulating Slc26a6 expression, whereas increase urine citrate via inhibiting Nadc1 expression. Moreover, glycine decreased the protein expression of both Slc26a6 and Nadc1 via increasing the expression of miRNA-411-3p, which directly bound to the 3'-untranslated regions of Slc26a6 and Nadc1 messenger RNAs, in vitro and in vivo. Together, our results revealed a novel role of glycine in the regulation of kidney CaOx crystal formation and provided a potential target for the treatment of kidney CaOx stone.

Study on the relationship between long non-coding RNA DHRS4-AS1 and disease-free survival in patients with osteosarcoma and its effect on osteosarcoma cell proliferation and migration in vitro / 肿瘤研究与临床

Objective:To investigate the relationship between long non-coding RNA (lncRNA) DHRS4-AS1 and disease-free survival in osteosarcoma patients and the mechanisms of its effect on proliferation and migration of osteosarcoma cells in vitro.Methods:The data of DHRS4-AS1 transcriptome levels and survival status of osteosarcoma patients in GEPIA database were collected since the database was established, and the patients were divided into high DHRS4-AS1 expression group and low DHRS4-AS1 expression group based on the median DHRS4-AS1 transcriptome level, with 59 cases in each group, and the Kaplan-Meier method was used to analyze the disease-free survival of the two groups. Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression of DHRS4-AS1 in osteosarcoma cell lines MG-63, HOS, 143B, U-2OS, Saos2 and normal osteoblast cell line hFOB1.19, and the osteosarcoma cell line with the lowest DHRS4-AS1 expression level was selected for subsequent experiments. The plasmid carrying DHRS4-AS1 sequence and the plasmid carrying negative control sequence were transfected into the selected osteosarcoma cells as DHRS4-AS1 group and control group. CCK-8 method was used to detect the proliferation of each group of cells, and the absorbance value was used as the cell proliferation ability; cell scratch assay was used to detect the migration of each group of cells. The bioinformatics website starBase V2.0 was used to predict the target genes of DHRS4-AS1, and the dual luciferase reporter gene assay was used to verify the targeting relationship between DHRS4-AS1 and the target genes. The expression levels of target genes and downstream genes of osteosarcoma cells in control group and DHRS4-AS1 group were detected by qRT-PCR and Western blotting.Results:Survival analysis showed that the disease-free survival of osteosarcoma patients in the high DHRS4-AS1 expression group in GEPIA database was superior to that of the low DHRS4-AS1 expression group ( P < 0.001). Compared with normal osteoblastic hFOB1.19 cells, the expression level of DHRS4-AS1 was low in all osteosarcoma cells (all P < 0.01), with the lowest expression level of DHRS4-AS1 in U-2OS cells ( P < 0.001). Cell proliferation ability was reduced in U-2OS cells of the DHRS4-AS1 group after 1, 2, 3 and 4 d of culture compared with the control group (all P < 0.05). The migration rate of U-2OS cells in the DHRS4-AS1 group was lower than that in the control group [(31±6)% vs. (63±4)%, t = 4.38, P = 0.005]. starBase V2.0 website predicted that DHRS4-AS1 complementarily bound to miRNA-411-3p (miR-411-3p); dual luciferase reporter gene assay showed that miR-411-3p overexpression reduced the luciferase activity of the wild-type DHRS4-AS1 reporter gene ( P < 0.001), but had no effect on the luciferase activity of the mutant DHRS4-AS1 reporter gene ( P > 0.05). qRT-PCR showed that the relative expression of miR-411-3p in U-2OS cells of the DHRS4-AS1 group was low (0.22±0.06 vs. 1.06±0.23, t = 3.55, P = 0.012) and the relative expression of metastasis suppressor MTSS1 mRNA was high (5.58±1.03 vs. 1.06±0.22, t = 4.28, P = 0.005) compared with the control group; Western blotting showed that MTSS1 expression was elevated, and the expression levels of cell proliferation phenotype proteins CDK3 and cyclin C and cell migration phenotype proteins ZEB2 and KLF8 were low. Conclusions:Osteosarcoma patients with high expression of lncRNA DHRS4-AS1 have better disease-free survival, and its expression is low in osteosarcoma cell lines. DHRS4-AS1 may promote MTSS1 gene expression and inhibit cell proliferation and migration by targeting and down-regulating miR-411-3p expression in osteosarcoma cells.