Scutellarein Ameliorated Chondrocyte Inflammation and Osteoarthritis in Rats

Objective:Osteoarthritis(OA)is a degenerative joint disorder characterized by the gradual degradation of joint cartilage and local inflammation.This study aimed to investigate the anti-OA effect of scutellarein(SCU),a single-unit flavonoid compound obtained from Scutellaria barbata D.Don,in rats.Methods:The extracted rat chondrocytes were treated with SCU and IL-1β.The chondrocytes were divided into control group,IL-1βgroup,IL-1β+SCU 50µmol/L group,and IL-1β+SCU 100µmol/L group.Morphology of rat chondrocytes was observed by toluidine blue and safranin O staining.CCK-8 method was used to detect the cytotoxicity of SCU.ELISA,qRT-PCR,Western blotting,immunofluorescence,SAβ-gal staining,flow cytometry,and bioinformatics analysis were applied to evaluate the effect of SCU on rat chondrocytes under IL-1βintervention.Additionally,anterior cruciate ligament transection(ACL-T)was used to establish a rat OA model.Histological changes were detected by safranin O/fast green,hematoxylin-eosin(HE)staining,and immunohistochemistry.Results:SCU protected cartilage and exhibited anti-inflammatory effects via multiple mechanisms.Specifically,it could enhance the synthesis of extracellular matrix in cartilage cells and inhibit its degradation.In addition,SCU partially inhibited the nuclear factor kappa-B/mitogen-activated protein kinase(NF-κB/MAPK)pathway,thereby reducing inflammatory cytokine production in the joint cartilage.Furthermore,SCU significantly reduced IL-1β-induced apoptosis and senescence in rat chondrocytes,further highlighting its potential role in OA treatment.In vivo experiments revealed that SCU(at a dose of 50 mg/kg)administered for 2 months could significantly delay the progression of cartilage damage,which was reflected in a lower Osteoarthritis Research Society International(OARSI)score,and reduced expression of matrix metalloproteinase 13(MMP13)in cartilage.Conclusion:SCU is effective in the therapeutic management of OA and could serve as a potential candidate for future clinical drug therapy for OA.

Regulation of CD137 expression through K-Ras signaling in pancreatic cancer cells

Background:The interaction between CD137 and its ligand(CD137L)plays a major role in the regulation of immune functions and affects cancer immunotherapy.CD137 is a cell surface protein mainly located on activated T cells,and its regulation and functions in immune cells are well established.However,the expression of CD137 and its regulation in cancer cells remain poorly understood.The main purposes of this study were to examine the expression of CD137 in pancreatic cancer cells and to investigate its underlying mechanisms.Methods:Cells containing inducible K-RasG12V expression vector or with different K-Ras mutational statuses were used as in vitro models to examine the regulation of CD137 expression by K-Ras.Various molecular assays were employed to explore the regulatory mechanisms.Tumor specimens from 15 pancreatic cancer patients and serum samples from 10 patients and 10 healthy donors were used to test if the expression of CD137 could be validated in clinical samples.Results:We found that the CD137 protein was expressed on the cell surface in pancreatic cancer tissues and cancer cell lines.Enzyme-linked immunosorbent assay revealed no difference in the levels of secreted CD137 in the sera of patients and healthy donors.By using the K-Ras inducible cell system,we further showed that oncogenic K-Ras up-regulated CD137 through the activation of MAPK(mitogen-activated protein kinases)and NF-κB(nuclear factor kappa-light-chain-enhancer of activated B cells)pathways,as evidenced by significantly reduced CD137 mRNA expression led by genetic silencing of MAPK1 and p65,the key proteins involved in the respective pathways.Further-more,we also found that the NF-κB pathway was mainly stimulated by the K-Ras-induced secretion of interleukin-1α(IL-1α)which promoted the transcription of the CD137 gene in pancreatic cancer cell lines.Analysis of the TCGA(the cancer genome atlas)database also revealed a significant correlation between IL-1αand CD137 expression(r=0.274)in tumor samples from pancreatic cancer patients(P<0.001).Conclusions:The present study has demonstrated that the CD137 protein was expressed on pancreatic cancer cell surface,and has identified a novel mechanism by which K-Ras regulates CD137 in pancreatic cancer cells through MAPK and NF-κB pathways stimulated by IL-1α.