查看更多>>摘要：Our previous study shows that activation of pregnane X receptor(PXR)exerts hepatoprotection against lithocholic acid(LCA)-induced cholestatic liver injury.In this study we investigated whether PXR activation could inhibit hepatocyte pyroptosis,as well as the underlying mechanisms.Male mice were treated with mouse PXR agonist pregnenolone 16α-carbonitrile(PCN,50 mg·kg-1·d-1,i.p.)for 7 days,and received LCA(125 mg/kg,i.p.,bid)from D4,then sacrificed 12 h after the last LCA injection.We showed that LCA injection resulted in severe cholestatic liver injury characterized by significant increases in gallbladder size,hepatocellular necrosis,and neutrophil infiltration with a mortality rate of 68％;PCN treatment significantly inhibited hepatocyte pyroptosis during LCA-induced cholestatic liver injury,as evidenced by reduced serum lactic dehydrogenase(LDH)levels,TUNEL-positive cells and hepatocyte membrane damage.Furthermore,PXR activation suppressed both the NOD-like receptor protein 3(NLRP3)inflammasome-induced canonical pyroptosis and the apoptosis protease activating factor-1(APAF-1)pyroptosome-induced non-canonical pyroptosis.Inhibition of the nuclear factor kappa B(NF-κB)and forkhead box O1(FOXO1)signaling pathways was also observed following PXR activation.Notably,dual luciferase reporter assay showed that PXR activation inhibited the transcriptional effects of NF-κB on NLRP3,as well as FOXO1 on APAF-1.Our results demonstrate that PXR activation protects against cholestatic liver injury by inhibiting the canonical pyroptosis through the NF-κB-NLRP3 axis and the non-canonical pyroptosis through the FOXO1-APAF-1 axis,providing new evidence for PXR as a prospective anti-cholestatic target.
查看更多>>摘要：The pyroptosis of renal tubular epithelial cells leads to tubular loss and inflammation and then promotes renal fibrosis.The transcription factor Krüppel-like factor 4(KLF4)can bidirectionally regulate the transcription of target genes.Our previous study revealed that sustained elevation of KLF4 is responsible for the transition of acute kidney injury(AKI)into chronic kidney disease(CKD)and renal fibrosis.In this study,we explored the upstream mechanisms of renal tubular epithelial cell pyroptosis from the perspective of posttranslational regulation and focused on the transcription factor KLF4.Mice were subjected to unilateral ureteral obstruction(UUO)surgery and euthanized on D7 or D14 for renal tissue harvesting.We showed that the pyroptosis of renal tubular epithelial cells mediated by both the Caspase-1/GSDMD and Caspase-3/GSDME pathways was time-dependently increased in UUO mouse kidneys.Furthermore,we found that the expression of the transcription factor KLF4 was also upregulated in a time-dependent manner in UUO mouse kidneys.Tubular epithelial cell-specific Klf4 knockout alleviated UUO-induced pyroptosis and renal fibrosis.In Ang Ⅱ-treated mouse renal proximal tubular epithelial cells(MTECs),we demonstrated that KLF4 bound to the promoter regions of Caspase-3 and Caspase-1 and directly increased their transcription.In addition,we found that ubiquitin-specific protease 11(USP11)was increased in UUO mouse kidneys.USP11 deubiquitinated KLF4.Knockout of Usp11 or pretreatment with the USP11 inhibitor mitoxantrone(3 mg/kg,i.p.,twice a week for two weeks before UUO surgery)significantly alleviated the increases in KLF4 expression,pyroptosis and renal fibrosis.These results demonstrated that the increased expression of USP11 in renal tubular cells prevents the ubiquitin degradation of KLF4 and that elevated KLF4 promotes inflammation and renal fibrosis by initiating tubular cell pyroptosis.
查看更多>>摘要：P60,a Foxp3 inhibitory peptide,can hinder the regulatory T cell(Treg)activity and impair tumor proliferation.However,low systemic stability and poor specificity have led to daily dosing to achieve therapeutic effect.Therefore,this study aims to improve P60 stability and specific delivery through its encapsulation in liposomes targeting CD25,constitutively expressed in Tregs.P60 liposomes formulated with DSPE-PEG750 or DSPE-PEG2000 were incubated with DSPE-PEG2000-Maleimide micelles conjugated to Fab'fragments of anti-CD25 to develop two targeted formulations or immunoliposomes(IL):IL-P602000(DSPE-PEG2000 only)and IL-P60750(combining DSPE-PEG750 and DSPE-PEG2000).P60 encapsulation efficiency was 50％-60％irrespective of PEG chain length.Treg uptake was 2.5 and 14 times higher for IL-PEG750 compared with IL-PEG2000 and non-targeted liposomes,respectively,in in-vitro assays.In fact,IL-P60750 allowed CD8+T cells ex-vivo proliferation in presence of Treg at doses 10-20 times lower than for free P60.Antitumor response of P60 and IL-P60750 in monotherapy and combined with anti-PD-1 was evaluated in MC38 and LLCOVA tumor bearing mice.In MC38 model,IL-P60750 monotherapy induced total tumor regression in 40％of mice reaching 100％for anti-PD-1 combination.This effect was associated with a significant increase in activated CD8+T cells in tumors.Notably,IL-P60750 also inhibited human Treg in ex-vivo assay,showing the translational capability of this formulation.In conclusion,IL-P60750 formulated with different PEG chain lengths,has demonstrated antitumor efficacy by selective inhibition of Treg activity and enhances the effect of anti-PD1.Altogether,this novel IL represents a promising nanoplatform for cancer immunotherapies.
查看更多>>摘要：The transcription factor STAT3 is a promising target for the treatment of non-small cell lung cancer(NSCLC).STAT3 activity is mainly dependent on phosphorylation at tyrosine 705(pSTAT3-Y705),but the modulation on pSTAT3-Y705 is elusive.By screening a library of deubiquitinases(Dubs),we found that the Otub1 increases STAT3 transcriptional activity.As a Dub,Otub1 binds to pSTAT3-Y705 and specifically abolishes its K48-linked ubiquitination,therefore preventing its degradation and promoting NSCLC cell survival.The Otub1/pSTAT3-Y705 axis could be a potential target for the treatment of NSCLC.To explore this concept,we screen libraries of FDA-approved drugs and natural products based on STAT3-recognition element-driven luciferase assay,from which crizotinib is found to block pSTAT3-Y705 deubiquitination and promotes its degradation.Different from its known action to induce ALK positive NSCLC cell apoptosis,crizotinib suppresses ALK-intact NSCLC cell proliferation and colony formation but not apoptosis.Furthermore,crizotinib also suppresses NSCLC xenograft growth in mice.Taken together,these findings identify Otub1 as the first deubiquitinase of pSTAT3-Y705 and provide that the Otub1/pSTAT3-Y705 axis is a promising target for the treatment of NSCLC.
查看更多>>摘要：A detailed chemical investigation of the Hainan soft coral Lobophytum crassum led to the identification of a class of polyoxygenated cembrane-type macrocyclic diterpenes(1-28),including three new flexible cembranoids,lobophycrasins E-G(2-4),and twenty-five known analogues.Their structures were elucidated by combining extensive spectroscopic data analysis,quantum mechanical-nuclear magnetic resonance(QM-NMR)methods,the modified Mosher's method,X-ray diffraction analysis,and comparison with data reported in the literature.Bioassays revealed that sixteen cembranoids inhibited the proliferation of H1975,MDA-MB231,A549,and H1299 cells.Among them,Compounds 10,17,and 20 exhibited significant antiproliferative activities with IC50 values of 1.92-8.82 μM,which are very similar to that of the positive control doxorubicin.Molecular mechanistic studies showed that the antitumour activity of Compound 10 was closely related to regulation of the ROR1 and ErbB3 signalling pathways.This study may provide insight into the discovery and utilization of marine macrocyclic cembranoids as lead compounds for anticancer drugs.
查看更多>>摘要：Aristolochic acids(AAs)have been identified as a significant risk factor for hepatocellular carcinoma(HCC).Ferroptosis is a type of regulated cell death involved in the tumor development.In this study,we investigated the molecular mechanisms by which AAs enhanced the growth of HCC.By conducting bioinformatics and RNA-Seq analyses,we found that AAs were closely correlated with ferroptosis.The physical interaction between p53 and AAs in HepG2 cells was validated by bioinformatics analysis and SPR assays with the binding pocket sites containing Pro92,Arg174,Asp207,Phe212,and His214 of p53.Based on the binding pocket that interacts with AAs,we designed a mutant and performed RNA-Seq profiling.Interestingly,we found that the binding pocket was responsible for ferroptosis,GADD45A,NRF2,and SLC7A11.Functionally,the interaction disturbed the binding of p53 to the promoter of GADD45A or NRF2,attenuating the role of p53 in enhancing GADD45A and suppressing NRF2;the mutant did not exhibit the same effects.Consequently,this event down-regulated GADD45A and up-regulated NRF2,ultimately inhibiting ferroptosis,suggesting that AAs hijacked p53 to down-regulate GADD45A and up-regulate NRF2 in HepG2 cells.Thus,AAs treatment resulted in the inhibition of ferroptosis via the p53/GADD45A/NRF2/SLC7A11 axis,which led to the enhancement of tumor growth.In conclusion,AAs-hijacked p53 restrains ferroptosis through the GADD45A/NRF2/SLC7A11 axis to enhance tumor growth.Our findings provide an underlying mechanism by which AAs enhance HCC and new insights into p53 in liver cancer.Therapeutically,the oncogene NRF2 is a promising target for liver cancer.
查看更多>>摘要：While immune checkpoint inhibitors(ICIs)are promising in the treatment of metastatic melanoma,about half of patients do not respond well to them.Low levels of human leukocyte antigen-DR(HLA-DR)in tumors have been shown to negatively influence prognosis and response to ICIs.Lysophosphatidic acid(LPA)is produced in large amounts by melanoma and is abundantly present in the tumor microenvironment.LPA induces the release of various cytokines and chemokines from tumor cells,which affect cancer development,metastasis,and tumor immunity.In the present study,we investigated the role of LPA-induced IL-10 release in regulating HLA-DR expression and the underlying mechanisms in human melanoma cells.We showed that LPA(0.001-10 μM)dose-dependently increased DR6 transcript levels through activating LPAR1 in HEK293T cells.Knockdown of NF-κB1 abrogated the LPA-increased DR6 expression without affecting basal DR6 expression in both A2058 and A375 melanoma cell lines.LPA(10 μM)significantly increased IL-10 transcripts in A2058 and A375 melanoma cells,the effect was abolished by pharmacological inhibition of LPAR1 or knockdown of DR6.We found a statistically significant correlation between the expression of LPAR1,DR6 and IL-10 in human melanoma tissue and an association between increased expression of LPAR1 and reduced effectiveness of ICI therapy.We demonstrated that LPA(10 μM)markedly suppressed HLA-DR expression in both A375 and A2058 melanoma cells via activating the LPAR1-DR6-IL-10 pathway.These data suggest that the LPAR1-DR6-IL-10 autocrine loop could constitute a novel mechanism used by tumor cells to evade immunosurveillance by decreasing HLA-DR expression.
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