Abrogation of USP7 is an alternative strategy to downregulate PD-L1 and sensitize gastric cancer cells to T cells killing

Targeting immune checkpoints such as programmed cell death protein 1 (PD-1) and programmed death ligand-1 (PD-L1) have been approved for treating melanoma, gastric cancer (GC) and bladder cancer with clinical benefit. Nevertheless, many patients failed to respond to anti-PD-1/PD-L1 treatment, so it is necessary to seek an alternative strategy for traditional PD-1/PD-L1 targeting immunotherapy. Here with the data from The Cancer Genome Atlas (TCGA) and our in-house tissue library, PD-L1 expression was found to be positively correlated with the expression of ubiquitin-specific processing protease 7 (USP7) in GC. Furthermore, USP7 directly interacted with PD-L1 in order to stabilize it, while abrogation of USP7 attenuated PD-L1/PD-1 interaction and sensitized cancer cells to T cell killing

Tubeimoside-1 induces TFEB-dependent lysosomal degradation of PD-L1 and promotes antitumor immunity by targeting mTOR

Programmed cell death ligand 1 (PD-L1)/programmed cell death protein 1 (PD-1) cascade is an effective therapeutic target for immune checkpoint blockade (ICB) therapy. Targeting PD-L1/PD-1 axis by small-molecule drug is an attractive approach to enhance antitumor immunity. Using flow cytometry-based assay, we identify tubeimoside-1 (TBM-1) as a promising antitumor immune modulator that negatively regulates PD-L1 level. TBM-1 disrupts PD-1/PD-L1 interaction and enhances the cytotoxicity of T cells toward cancer cells through decreasing the abundance of PD-L1. Furthermore, TBM-1 exerts its antitumor effect in mice bearing Lewis lung carcinoma (LLC) and B16 melanoma tumor xenograft

Discovery of 1,2,3triazolo4,5-pyrimidine derivatives as highly potent, selective, and cellularly active USP28 inhibitors

Ubiquitin specific peptidase 28 (USP28) is closely associated to the occurrence and development of various malignancies, and thus has been validated as a promising therapeutic target for cancer therapy. To date, only few USP28 inhibitors with moderate inhibitory activity have been reported, highly potent and selective USP28 inhibitors with new chemotypes remain to be discovered for pathologically investigating the roles of deubiquitinase. In this current study, we reported the synthesis and biological evaluation of new [1,2,3]triazolo[4,5-]pyrimidine derivatives as potent USP28 inhibitors. Especially, compound potently inhibited USP28 (IC = 1.10 ± 0.02 μmol/L,  = 40 nmol/L), showing selectivity over USP7 and LSD1 (IC > 100 μmol/L). Compound was cellularly engaged to USP28 in gastric cancer cells. Compound reversibly bound to USP28 and directly affected its protein levels, thus inhibiting the proliferation, cell cycle at S phase, and epithelial-mesenchymal transition (EMT) progression in gastric cancer cell lines. Docking studies were performed to rationalize the potency of compound . Collectively, compound could serve as a new tool compound for the development of new USP28 inhibitors for exploring the roles of deubiquitinase in cancers.

Berberine diminishes cancer cell PD-L1 expression and facilitates antitumor immunity

Programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) blocking therapy has become a major pillar of cancer immunotherapy. Compared with antibodies targeting, small-molecule checkpoint inhibitors which have favorable pharmacokinetics are urgently needed. Here we identified berberine (BBR), a proven anti-inflammation drug, as a negative regulator of PD-L1 from a set of traditional Chinese medicine (TCM) chemical monomers. BBR enhanced the sensitivity of tumour cells to co-cultured T-cells by decreasing the level of PD-L1 in cancer cells. In addition, BBR exerted its antitumor effect in Lewis tumor xenograft mice through enhancing tumor-infiltrating T-cell immunity and attenuating the activation of immunosuppressive myeloid-derived suppressor cells (MDSCs) and regulatory T-cells (Tregs). BBR triggered PD-L1 degradation through ubiquitin (Ub)/proteasome-dependent pathway. Remarkably, BBR selectively bound to the glutamic acid 76 of constitutive photomorphogenic-9 signalosome 5 (CSN5) and inhibited PD-1/PD-L1 axis through its deubiquitination activity, resulting in ubiquitination and degradation of PD-L1. Our data reveals a previously unrecognized antitumor mechanism of BBR, suggesting BBR is small-molecule immune checkpoint inhibitor for cancer treatment.

Effects of cycloheximide on the mortality of Atta sexdens leaf-cutting worker ants

ABSTRACT Leaf-cutting ants live symbiotically with a fungus that they cultivate on the plant leaves that they cut. The innumerous studies on the plant selection mechanism used by leaf-cutting ants show the researchers' interest in this issue. Many classical studies propose that plants are selected according to the fungus garden nutritional needs and the absence of potentially harmful substances. This hypothesis is corroborated by behavioral experiments using cycloheximide (fungicide) with citric pulp or forage plants greatly accepted by leaf-cutting ants. According to this hypothesis, under the action of a fungicide, the fungus emits an allomone that informs worker ants that some food is inadequate to its growth. Although some authors state that the cycloheximide "fungicide" used is specific and non toxic to ants, our findings are distinct. In our study, various concentrations of cycloheximide were administered orally to leaf-cutting worker ants in a citric pulp paste diet. After the ingestion period, the ants were isolated and offered the symbiotic fungus for 21 days and the mortality rate was evaluated. As expected, the treatment with 0.01% cycloheximide showed a low mortality rate (8.86%). At 0.1%, the mortality rate was mild (27.85%), and treatment with 1% cycloheximide resulted in moderate mortality (45.57%). In contrast, the positive control with 0.1% sulfluramid showed a high mortality rate (91.14%). Therefore, we concluded that the ingestion of high concentrations of cycloheximide results in a moderate mortality rate in leaf-cutting worker ants.

Protective effect and its mechanism of codonopsis pilosula polysaccharide on memory consolidation disorder induced by cycloheximide in mice / 中国药理学与毒理学杂志

OBJECTIVE To investigate the protective effect of Codonopsis Pilosula Polysaccharide (CPPS) on improving of the memory consolidation disorder induced by Cycloheximide and its possible mechanisms in mice. METHODS The mice was divided into five groups, as normal control group, cycloheximid model group, piracetam positive control group, CPPS 300 mg · kg- 1 group, and CPPS 150 mg·kg-1 group. The mice respectively were given saline, piracetam, and CPPS for 15 d. The memory consolidation disorder model in mice was established by ip. Cyclohexylamine, and orally administered CPPS(300 mg·kg-1 or 150 mg·kg-1) every day. Then experimental groups were subjected Morris Water Maze test. Western blotting analysis were used to analysis the expression of CaMKⅡ/CREB signaling pathways. RESULTS Morris water maze experiment showed that cyclohexylamine can cause memory consolidation disorder(P<0.01), and giving piracetam and CPPS (300 mg · kg- 1) can improve spatial memory impairment in mice(P<0.05, P<0.01). Western blotting experiment results show that compared with normal control group, CaMKⅡ and CREB contents of brain in model group mice had significant decreased(P<0.001); Compared with model group, CaMK Ⅱ and CREB contents of brain tissue in piracetam and CPPS groups increased significantly(P<0.05,P<0.01,P<0.001). CONCLUSION Cyclo?heximide can induce the memory consolidation disorder, and its effect in mice related to CaMK/CREB signaling pathways. CPPS can improved this memory disorder by influence CaMKⅡ/CREB signaling pathways.

Compounds used to produce cloned animals are genotoxic and mutagenic in mammalian assays in vitro and in vivo

The compounds 6-dimethylaminopurine and cycloheximide promote the successful production of cloned mammals and have been used in the development of embryos produced by somatic cell nuclear transfer. This study investigated the effects of 6-dimethylaminopurine and cycloheximide in vitro, using the thiazolyl blue tetrazolium bromide colorimetric assay to assess cytotoxicity, the trypan blue exclusion assay to assess cell viability, the comet assay to assess genotoxicity, and the micronucleus test with cytokinesis block to test mutagenicity. In addition, the comet assay and the micronucleus test were also performed on peripheral blood cells of 54 male Swiss mice, 35 g each, to assess the effects of the compounds in vivo. The results indicated that both 6-dimethylaminopurine and cycloheximide, at the concentrations and doses tested, were cytotoxic in vitro and genotoxic and mutagenic in vitro and in vivo, altered the nuclear division index in vitro, but did not diminish cell viability in vitro. Considering that alterations in DNA play important roles in mutagenesis, carcinogenesis, and morphofunctional teratogenesis and reduce embryonic viability, this study indicated that 6-dimethylaminopurine and cycloheximide utilized in the process of mammalian cloning may be responsible for the low embryo viability commonly seen in nuclear transfer after implantation in utero.

Synthesis of von willebrand factor antigen in chlamydophila pneumoniae-infected endothelial cells.

Objective: The main objective of our study was to evaluate the response of endothelial cells infected with Chlamydophila pneumoniae (C. pneumoniae), by using von Willebrand factor (vWf) antigen as a marker for endothelial damage and dysfunction. Another objective was to evaluate the effect of cycloheximide on C. pneumoniae infectivity and vWf secretion from human umbilical vein endothelial cells (HUVECs). Methods: HUVECs were harvested. After first passage, the HUVECs were inoculated with C. pneumoniae in three concentrations of cycloheximide (0, 1, and 2 µg/ml). At 24, 48, and 72 hours post-inoculation, supernatants from each HUVEC culture well were collected and measured for vWf antigen by sandwich ELISA as well as non-infected HUVECs were used as controls. C. pneumoniae infectivity was evaluated by indirect immunofluoresce technique and polymerase chain reaction. Results: The cycloheximide-treated HUVECs resulted in greater infection compared to the non-treated HUVECs. Means of vWf antigens from HUVECs infected with C. pneumoniae were not different from those of non-infected HUVECs. However, there was a significant change in vWf secretion when different concentrations of cycloheximide were used in the culture system. Conclusion: From our study, the results of vWf antigen secreted from HUVECs did not support the direct endothelial damage effect caused by C. pneumoniae infection. Therefore, vWf antigen is not a sensitive marker for this event. Furthermore, results from this study supported the infectious ability of C. pneumoniae on HUVECs and the importance of cycloheximide in improving the infectivity of this organism. However, the investigators had to use this substance cautiously, especially in protein synthesis study. Nevertheless, a non-variable dose of C. pneumoniae and the use of only one surrogate endothelial damage marker may limit the interpretation of this study.

Protective Effects of Focal Ischemic Preconditioning and HSP70 Expression on Middle Cerebral Artery Occlusion in Rats / 华中科技大学学报（医学）（英德文版）

To systematically evaluate the importance of protein synthesis in ischemic preconditioning (PC)-induced ischemic tolerance (IT), temporary middle cerebral artery occlusion (MCAO)by Longa (20 min) was used for PC (ischemic precondioning). Twenty-four hours of reperfusion was allowed after PC and before permanent MCAO to establish ischemic tolerance (IT) to compare with non-PC (sham-operated) rats (n=5 for each group). Infarct size and neurological deficits were measured 24 h after PMCAO. Samples of brain were taken for the determination of HSP70 expression by Western blot analysis. The effects of the protein synthesis inhibitor cycloheximide administered just before PC or administered long after PC but just before PMCAO on IT were also determined (n=5 for each group). Our results showed that hemispheric infarct was significantly reduced (P＜0.01) only if PC was performed after 24 h, and PC significantly (P＜0.05) reduced neurological deficits (similar to reductions in infarct size). Cycloheximide eliminated ischemic PC-induced IT effects on both brain injury and neurological deficits if administered before PC but not if administered long after PC but before PMCAO. PC produced no brain injury but did increase HSP70 protein 24 h after PC. Cycloheximide eliminated that effect. The results suggest that PC is a powerful inducer of ischemic brain tolerance as reflected by the preservation of brain tissue and motor function. PC induces IT that is dependent on de novo protein synthesis.

The translation inhibitor anisomycin induces Elk-1-mediated transcriptional activation of egr-1 through multiple mitogen-activated protein kinase pathways

The early growth response-1 gene (egr-1) encodes a zinc-finger transcription factor Egr-1 and is rapidly inducible by a variety of extracellular stimuli. Anisomycin (ANX), a protein synthesis inhibitor, stimulates mitogen-activated protein kinase (MAPK) pathways and thereby causes a rapid induction of immediate-early response genes. We found that anisomycin treatment of U87MG glioma cells resulted in a marked, time-dependent increase in levels of Egr-1 protein. The results of Northern blot analysis and reporter gene assay of egr-1 gene promoter (Pegr-1) activity indicate that the ANX- induced increase in Egr-1 occurs at the transcriptional level. Deletion of the serum response element (SRE) in the 5'-flanking region of egr-1 gene abolished ANX-induced Pegr-1 activity. ANX induced the phosphorylation of the ERK1/2, JNK, and p38 MAPKs in a time-dependent manner and also induced transactivation of Gal4-Elk-1, suggesting that Elk-1 is involved in SRE-mediated egr-1 transcription. Transient transfection of dominant-negative constructs of MAPK pathways blocked ANX-induced Pegr-1 activity. Furthermore, pretreatment with specific MAPK pathway inhibitors, including the MEK inhibitor U0126, the JNK inhibitor SP600125, and the p38 kinase inhibitor SB202190, completely inhibited ANX-inducible expression of Egr-1. Taken together, these results suggest that all three MAPK pathways play a crucial role in ANX-induced transcriptional activation of Pegr-1 through SRE-mediated transactivation of Elk

Neuroprotective Effect of Cycloheximide on Hypoxic-Ischemic Brain Injury in Neonatal Rats

This study was done to determine the neuroprotective effect of cycloheximide on neonatal hypoxic-ischemic brain injury. Seven day-old newborn rat pups were subjected to 90 min of 8% oxygen following a unilateral carotid artery ligation. The extent of cerebral infarction was evaluated at 1 and 4 week of recovery. Apoptosis was identified by performing terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining and flow cytometry with a combination of fluoresceinated annexin V and propidium iodide. Brain infarction area was significantly increased at 4 week compared to 1 week after hypoxia-ischemia in the control group. With cycloheximide treatment, the number of TUNEL positive cells in the ipsilateral cerebral cortex at 48 hr and peri-infarct area at 1 and 4 week of recovery was significantly reduced, both apoptotic and necrotic cells by flow cytometry 48 hr after the injury were significantly reduced, and the extent of cerebral infarction at 1 and 4 week of recovery was also significantly attenuated compared to the hypoxia-ischemia control group. In summary, our data suggest that apoptosis plays an important role in the development of delayed infarction, and inhibition of apoptosis with cycloheximide significantly reduces the ensuing cerebral infarction in a newborn rat pup model of cerebral hypoxia-ischemia.

Therapeutic Window for Cycloheximide Treatment after Hypoxic-Ischemic Brain Injury in Neonatal Rats

We have previously shown that cycloheximide significantly inhibited apoptosis, and reduced ensuing cerebral infarction in a newborn rat model of cerebral hypoxiaischemia. This study was performed to determine the therapeutic window for cycloheximide therapy. Seven day-old newborn rat pups were subjected to 100 min of 8% oxygen following a unilateral carotid artery ligation, and cycloheximide was given at 0, 6, 12 and 24 hr after hypoxia-ischemia (HI). Apoptosis or necrosis was identified by performing flow cytometry with a combination of fluorescinated annexin V and propidium iodide, and the extent of cerebral infarction was evaluated with triphenyl tetrazolium chloride (TTC) at 48 hr and 72 hr after HI, respectively. With cycloheximide treatment at 0 hr after HI, both apoptotic and necrotic cells by flow cytometry were significantly reduced, only necrotic cells were significantly reduced at 6 and 12 hr, and no protective effect was seen if administration was delayed until 24 hr after HI compared to the HI control group. Infarct volume, measured by TTC, was significantly reduced by 92% and 61% when cycloheximide was given at 0 or 6 hr after HI respectively; however, there was an insignificant trend in infarct reduction if cycloheximide was administered 12 hr after HI, and no protective effect was observed when administration was delayed until 24 hr after HI. In summary, cycloheximide was neuroprotective when given within 6 hr after HI in the developing newborn rat brain.

Fas-mediated apoptosis and expression of related genes in human malignant hematopoietic cells

Fas transduces apoptotic signals upon cross-linking with the Fas ligand (FasL), which is experimentally replaced by agonistic anti-Fas monoclonal antibodies (mAb). Of eight human malignant hematopoietic cell lines (HL-60, KG-1, THP-1, K562, U937, Jurkat, IM-9, RPMI-8226) examined by flow cytometric analysis, all, except K562, were found to be positive for surface Fas antigen. However, despite surface Fas expression, the agonistic anti-Fas mAb (7C11) induced apoptosis in only three of seven Fas-expressing cell lines (KG-1, Jurkat and IM-9). This Fas-resistance did not correlated with high levels of mRNA either for DcR3, a decoy receptor for FasL, or for FAP-1, a Fas-associated phosphatase that can block the apoptotic function of Fas. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis did not show consistent differences in the expression of Bcl-2 and Bax between Fas-sensitive and Fas-resistant cell lines examined. These findings indicated that the presence or absence of mRNA expression of DcR3, FAP-1, Bcl-2 and Bax did not always correlate with relative sensitivity to Fas-mediated apoptosis. Treatment of cells with cycloheximide converted the phenotype of resistant cell lines from Fas-resistant to Fas-sensitive, and enhanced the sensitivity of Fas-sensitive cell lines. These results suggest that the Fas-resistance is dependent on the presence of labile proteins that determine resistance to Fas-mediated apoptosis and the apoptotic machinery is already in place in Fas-resistant cell lines.

Effects of glutamate receptor antagonists and protein synthesis inhibitor on delayed neuronal death induced by transient global ischemia in rat brain

It has been well documented that transient forebrain global ischemia causes selective neuronal degeneration in hippocampal CA1 pyramidal neurons with a delay of a few days. The mechanism of this delayed hippocampal CA1 pyramidal neuronal death (DND) is still controversial. To delineate the mechanisms of the DND, the effects of treatment with MK-801, an NMDA receptor antagonist, kynurenic acid, a NMDA/non-NMDA receptor antagonist, and/or cycloheximide, a protein synthesis inhibitor, on the DND were investigated in male Wistar rats. To examine the participation of apoptotic neuronal death in the DND, TUNEL staining was performed in ischemic brain section. Global ischemia was induced by 4-vessel occlusion for 20 min. All animals in this study showed the DND 3 and 7 days after the ischemic insult. The DND that occurred 3 days and 7 days after the ischemia were not affected by pretreatment with MK-801 (I mg/kg), but markedly attenuated by the pretreatment with kynurenic acid (500 mg/kg). Treatment with cycloheximide (1 mg/kg) also markedly inhibited the DND. The magnitudes of attenuation by the two drugs were similar. The magnitude of attenuation by co-treatments with kynurenic acid and cycloheximide was not greater than that with any single treatment. TUNEL staining was negative in the sections obtained 1 or 2 days after the ischemic insults, but it was positive at hippocampal CA1 pyramidal cells in sections collected 3 days after the ischemia. These results suggested that the DND should be mediated by the activation of non-NMDA receptor, not by the activation of NMDA receptor and that the activation of AMPA receptor should induce the apoptotic process in the DND.

Effects of actinomycin D and cycloheximide on gonadotropin- or 17α., 20β-dihydroxy-4- pregnen-3-one-induced in vitro maturation in oocytes of the catfish, Clarias batrachus.

The effect of inhibitors in the oocyte maturation of Clarias batrachus, was investigated in vitro using actinomycin D and cycloheximide. Full-grown immature oocytes incubated with salmon gonadotropin (SG-G100) and 17α, 20ß-dihydroxy-4-pregnen-3-one at the concentration of 1 μg/ml induced 86·0 ± 1·2% and 91·3 ± 2·4% of germinal vesicle breakdown, respectively. When the oocytes were incubated with SG-G100 (1 μg/ml) + different concentrations of actinomycin D or cycloheximide, a significant drop in the frequency of germinal vesicle breakdown was observed. Thus, gonadotropin-induced maturation was inhibited by both transcriptional and translational inhibitors. When the oocytes were incubated with 17α, 20ß-dihydroxy-4-pregnen-3-one (1μg/ml) + different concentrations of cycloheximide, a significant inhibition of germinal vesicle breakdown was recorded. However, the maturation was not inhibited when the oocytes were incubated in the presence of 17α, 20ß-dihydroxy-4-pregnen-3-one (1 μg/ml) and different concentrations of actinomycin D. This suggests that mRNA synthesis is not obligatory for 17α, 20β- dihydroxy-4-pregnen-3-one induced oocyte maturation. Based on the time course experiment, it was observed that the inhibition of maturation in cycloheximide treated oocytes extends up to 12 h after which the effect becomes slowly subdued.

Transcription of class II MHC gene by interferon-gamma in FRTL-5 cells

The intracellular mechanism by which interferon-gamma induces the expression of class II major histocompatibility complex (MHC) antigen in nonlymphoid cells is not clear. The effect of recombinant rat interferon-gamma (IFN-gamma), and cycloheximide on the expression of class II MHC gene was studied using the techniques of immunocytochemical staining and northern blot analysis. IFN-gamma induced de novo transcription of class II MHC gene and class II MHC antigen expression on the cell surface. Cycloheximide did not inhibit IFN-gamma-induced class II MHC antigen expression in a dose-dependent manner indicating translational blockade. These results suggest that IFN-gamma induces class II MHC antigen expression via de novo transcription of class II MHC gene leading to synthesis of new class II MHC molecule.

Serum immunopharmacological assessment:effects of cycloheximide on the activation of T lymphocytes of mouse / 中国病理生理杂志

AIM: To investigate the effect of cycloheximide on the T cells activation by mitogen in vitro with CD69 expression as activation marker for the application of this drug clinically. METHODS:Lymphocytes were isolated from lymphoid nodes of C57BL/6 mouse. The cells were preincubated with cycloheximide(CHX), 5% serum containing CHX respectively for an hour, then further incubated with polyclonal activators (Con A or PDB). Harvesting the cells after whole incubation for 24 h, we estimated the expression rates of CD69 on T cells by flow cytometry following two-color immunofluorescent staining. RESULTS: The expression rates of CD69 on the T cells preincubated with CHX, serum containing CHX after the stimulation in response to Con A or PDB all showed significant difference with the expression rates of control group, respectively ( P

THE PROTECTIVE EFFECTS OF DRUGS ON APOPTOSIC NEURAL CELLS AFTER SPINAL CORD INJURY / 解放军医学杂志

To study the protective effects and the mechanism of drugs on apoptosic neural cells after spinal cord injury and the mechanism of their effects on severe degree compression injury to the lower thoracic spinal cord (T 8.9). Rats were divided into four groups randomly . The first group of rats were treated with saline solution(20?l) intrathecally after injury, the second group with cyceoheximide (CH)(30?g/20?l) intrathecally, the third group with monosialicganglioside(GM)(100?g/20?l),and the fourth group methylprednisolone(MP)(30mg/kg). The changes in weight, spinal cord blood flow(SCBF), terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL),neurological function and quantitative histological changes were observed.The results indicated that drugs had little effects on the SCBF. But drugs could improve the neurological function and area of spared normal tissue, and obviously reduce the number of TUNEL-positive cells. The results suggested that drugs had neuroprotective effects on the injuried spinal cord. The mechanism of the beneficial effects might be a reduction in neuronal cells apoptosis.