AIM: To investigate the effects of high-concentration glucose on the cell viability of retinal pigment epithelialcells(ARPE-19)/ human umbilical vein endothelial cells(HUVEC)cells, as well as on the expression levels of sirtuin 6(SIRT6).

METHODS:ARPE-19 and HUVEC cells were cultured for 48 h in media containing various glucose concentrations(5.5, 25, 50, 75, 100 mmol/L)and cellular morphology was observed under an optical microscope.Cell viability was assessed using the CCK-8 assay. Flow cytometry was utilized to evaluate apoptosis levels, and Western blot analysis was conducted to measure the expression of Bcl-2 and SIRT6. ARPE-19/HUVEC cells were treated with 50 mmol/L glucose for 48 h, after which immunofluorescence staining was performed to determine the subcellular localization and expression level of SIRT6 protein. In parallel, cells receiving the same treatment were harvested at different time points(0, 6, 12, 24, 36, 48, and 72 h), and the temporal changes in SIRT6 protein expression were assessed by Western blot analysis. SIRT6 overexpressing stable ARPE-19/HUVEC cell lines were constructed. Western blot was performed to detect the effects of SIRT6 overexpression on the expression levels of glucose transporters in ARPE-19/HUVEC cells treated with high glucose(50 mmol/L glucose).

RESULTS:Compared with the 5.5 mmol/L glucose group, cell number was decreased and cell viability was significantly reduced in ARPE19/HUVEC cells with increasing glucose concentrations(all P<0.01). Meanwhile, the protein expression level of SIRT6 was markedly downregulated(P<0.05). Such inhibitory effects exhibited both concentration-and time-dependent patterns(all P<0.05). Furthermore, high glucose induced cell apoptosis and downregulated the protein expression of Bcl-2(P<0.05). Immunofluorescence staining revealed that SIRT6 protein was predominantly localized in the nucleus after 48 h of high-glucose treatment, accompanied by pyknosis and nuclear fragmentation. After incubation with highg-lucose medium(50 mmol/L glucose)for different durations, long-term high-glucose intervention was found to reduce SIRT6 protein expression in ARPE19/HUVEC cells. Successful construction of the SIRT6-overexpressing stable ARPE-19/HUVEC cell lines was confirmed via immunofluorescence and Western blotting. Western blot analysis revealed that, compared with the HG+LV-con group, the HG+LV-SIRT6 group exhibited no significant differences in GLUT1 or GLUT4 expression in ARPE-19 cells, whereas GLUT3 expression was elevated(P<0.05). Compared with the HG+LV-con group, the HG+LV-SIRT6 group showed no significant change in GLUT1 expression, while GLUT3 and GLUT4 levels were increased(both P<0.05).

CONCLUSION:High-concentration glucose-reduce the proliferative activity of ARPE-19/HUVEC cells, induce apoptosis, and downregulate SIRT6 expression. SIRT6 may alleviate high glucose-induced retinal cell damage by promoting the expression of glucose transporters.

Osteosarcoma, a highly malignant tumor originating from bone tissue, is characterized by a high mortality along with a poor prognosis. The heterogeneity of the tumor microenvironment plays a pivotal role in its development and prognosis. Single-cell sequencing technology emerges as a crucial tool in elucidating this heterogeneity by delineating the functional characteristics and gene expression patterns of tumor cells, immune cells, and stromal cells within osteosarcoma tissues. This technology enables the depiction of the intricate interaction network between these cells. Utilizing the high-resolution advantage of single-cell sequencing, novel cell subtypes such as SPP1 (+) macrophages, C1QC (+) macrophages, and CLEC11A (+) B cells have been identified in osteosarcoma tissues, contributing to tumor growth and invasion within the tumor microenvironment. Identification of osteosarcoma stem cell subpopulations suggests that SERPINA1_CSCL1, FUS_CSCL2, and SPP1_CSCL3 populations may serve as the origin of osteosarcoma cells. Moreover, single-cell sequencing has revealed that mregDCs promote immune escape and tumor progression by selectively expressing CCR7, CCL17, CCL19, and CCL22 factors, thereby recruiting Treg cells. Additionally, this technology aids in the development of personalized chemotherapy regimens by pinpointing potential drug resistance targets in osteosarcoma, leading to the establishment of a drug resistance risk score model. In terms of disease prognosis, single-cell sequencing has identified immune infiltration-associated genes in osteosarcoma (e.g., EPHX2, FDPS, GBP1, MMD, ZYX), facilitating the construction of a prognostic analysis model for osteosarcoma patients, thus aiding in prognostic prediction.

Objective To explore the changes in the expression of glucose transporters 1/4(GLUT1/4)and Sirtuins in the retina of rats with diabetes.Methods Twenty 8-week-old healthy male Sprague-Dawley rats were randomly divid-ed into normal control and diabetic groups.Rats in the diabetic group received a disposable intraperitoneal injection of 60 mg·kg-1 streptozotocin to induce the diabetes model,while rats in the normal control group were injected with an equiva-lent amount of solvent.Body weight and blood glucose were measured at 2-week intervals.At 12 weeks after modeling,color Doppler ultrasound was applied to detect blood flow parameters in the central retinal artery(CRA)of rats;after an-esthetizing rats with sodium pentobarbital,eyeballs were harvested,and the pathological changes of rat retinal tissue were observed by hematoxylin & eosin(HE)staining.The expression of messenger ribonucleic acid(mRNA)for GLUT 1/4 and Sirtuins in the retina of rats were detected by immunohistochemical staining,Western blot and quantitative of reverse tran-scription polymerase chain reaction(qRT-PCR),respectively.Results At 12 weeks after modeling,compared with the normal control group,peak systolic velocity and end diastolic velocity were significantly lower in CRA of rats in the diabetic group(both P＜0.001);there were no significant differences in resistance index and pulsatility index(both P＞0.05).The HE staining results at 12 weeks after modeling showed that rats in the normal control group had clear structure in each layer of retinal tissues,closely and regularly arranged cells,and no obvious pathological changes;rats in the diabetic group showed decreased retinal thickness,blurred boundary of each layer,disordered structure and reduced cell number.Immu-nohistochemical staining at 12 weeks after modeling showed that GLUT 1 was mainly located in the retinal pigment epithelial layer of rats,and GLUT 4 was located in the ganglion cell layer,inner plexiform layer and photoreceptor layer.Western blot results showed that the relative expression of GLUT1 and GLUT 4 protein in the diabetic group were lower than that in the normal control group(both P＜0.05),and the relative expression of SIRT1-SIRT7 protein in the retina of rats in the di-abetic group were lower than those of the normal control group(all P＜0.05).qRT-PCR showed a decreased relative ex-pression of SIRT1-SIRT7 mRNA in the retina of rats in the diabetic group compared with that of the normal control group(allP＜0.01).Conclusion Diabetes can cause altered expression of GLUT1/4 and Sirtuins in the retinal tissue of rats,and GLUT1/4 and Sirtuins may be involved in the occurrence and development of diabetic retinopathy.

AIM:To study the expression of glucose transporters(GLUTs)and silent information regulators(SIRTs/sirtuins)in the liver of diabetic rats and human hepatocytes(LO2 cells)treated with high glucose.METHODS:(1)Twenty male SD rats were randomly divided into normal control(NC)group and diabetes mellitus(DM)group.The rats in DM group were given single intraperitoneal injection of streptozotocin(STZ,60 mg/kg)to establish the DM model,while the rats in NC group were intraperitoneally injected with equal volume of solvent once.Fasting blood glucose(FBG)and body mass were measured every 2 weeks.After 12 weeks of rearing,the blood and liver tissues of the rats were ob-tained after anesthesia with 1%sodium pentobarbitone,the biochemical indicators of blood were detected,and the liver in-dex was calculated.Hematoxylin-eosin(HE)staining and periodic acid-Schiff(PAS)staining were used to observe liver histopathological changes.Lipid accumulation in liver tissues was detected by oil red O staining.The expression levels of GLUTs and SIRTs family member proteins were detected in rat liver tissues.(2)The LO2 cells were treated with different concentrations of glucose for 48 h.The viability of the cells in each group was measured by CCK-8 assay,and Western blot was used to detected the protein expression levels of GLUTs and SIRTs in the cells.RESULTS:(1)Compared with NC group,the rats in DM group were depressed,lost weight,and the FBG and liver index were significantly increased(P＜0.05).The results of HE staining showed that the hepatic sinuses were dilatated and congested near the central vein in DM rats,and mild edema and scattered infiltration of inflammatory cells were found in liver cells.The results of oil red O staining showed the red fat droplets were diffusely scattered within liver cells in DM group.The results of PAS staining showed that there were numerous diffuse light purple circular droplets in the cytoplasm of the liver cells in the central ve-nous area of the DM rats.Western blot showed that the protein levels of GLUTs were higher and the protein levels of SIRTs were lower than those in NC group(P＜0.01).(2)The results of CCK-8 assay showed that the viability of LO2 cells was increased in 50 mmol/L glucose group(P＜0.01),without significant difference in 75,100 and 125 mmol/L glucose groups(all P＞0.05),and decreased in 150,175 and 200 mmol/L glucose groups(all P＜0.01).Later,150 mmol/L glu-cose was used as the high-glucose intervention condition.Western blot showed that the protein levels of GLUTs and SIRTs in LO2 cells under high glucose intervention were consistented with the results in animal experiments.CONCLUSION:High concentration of glucose can cause liver damage in SD rats and reduce the viability of human hepatocytes(LO2 cells).It can also increase the expression of GLUTs and decrease the expression of SIRTs in rat liver tissues and LO2 cells.Therefore,GLUTs and SIRTs family members may be the target proteins of diabetes-induced liver injury.