A new inhibitor of human peptide deformylase suppresses cell proliferation and induces cell apoptosis and autophagy in cancers.

Human peptide deformylase (hsPDF) has been found overexpressed in many cancer cells and its inhibitors exhibit antitumor activity. Studies were performed to validate that hsPDF is a good antitumor target. The inhibitory effect of PDF64 on hsPDF enzymatic activity was measured and confirmed by computation analysis. Antiproliferation activity was determined and in-vivo antitumor activity were analyzed in HCT116 and HL60 nude mice xenografts. Mitochondrial membrane potential (MMP), cell apoptosis, and autophagic cell death were analyzed by flow cytometry. ATP level was quantified using an ATP assay kit. Protein expression and kinase phosphorylation were determined by western blotting. A new hsPDF inhibitor PDF64 was identified. It showed evident antiproliferation activity in 10 cancer cells and significantly suppressed tumor growth in HCT116 and HL60 xenografts. It induced an obvious decrease in MMP and caused apparent cell apoptosis and autophagy in HCT116 and Jurkat cells. PDF64 treatment also led to an evident decrease in cellular ATP levels in these cells. Moreover, PDF64 downregulated c-Myc expression and had some effects on extracellular regulated protein kinases (ERK) and protein kinase B (Akt)/ mammalian target of rapamycin (mTOR) pathways. PDF64 exhibited good antitumor effects both in vivo and in vitro . It caused cell apoptosis and autophagic death in HCT116 and Jurkat cells. The effects may be mediated by inhibiting c-Myc expression and ERK or PI3K-Akt-mTOR pathway. Therefore, PDF64 may be a promising reagent for antitumor drug development, which further supports that hsPDF is a good antitumor drug target.

Pharmacological activation of the p53 pathway by a new compound CYZ2017 exerts anti-tumor effects.

Blockage of p53-MDM2 protein-protein interaction has long been a promising strategy of drug development for cancers with wild type p53. In this study, we report a new p53-MDM2 interaction inhibitor, CYZ2017, which could induce p53 nuclear translocation and possess p53-dependent anti-proliferation activity in a range of cancer cells. CYZ2017 treatment led to increase of p53 levels and induced the transactivation of its target genes p21. In addition, CYZ2017 induced G0/G1 cell cycle arrest and apoptosis in HCT116 cells. Besides, CYZ2017 suppressed tumor growth in a HCT116 xenograft model without visible toxicity. These results support that CYZ2017 might be a promising p53-MDM2 interaction inhibitor with good anti-tumor activity. Our finding provides some cues for further investigation of developing anti-tumor drugs based on the blockage of p53-MDM2 interaction.

Cytotoxic secondary metabolites from the vulnerable conifer Cephalotaxus oliveri and its associated endophytic fungus Alternaria alternate Y-4-2.

Rare and endangered plants (REPs) and their associated endophytes survived in unique habitats are promising sources for natural product-derived drug discovery. In this study, six new (cephaloverines A-F, 1-6, resp.) and 16 known (11-26) cephalotaxine-type alkaloids, together with three new (oliverbiflavones A-C, 7-9, resp.) and 11 known (27-37) biflavonoids were isolated and characterized from the twigs and leaves of Cephalotaxus oliveri, an endangered plant endemic to China. Meanwhile, a preliminary investigation on the secondary metabolites from a selected fungal endophyte (i.e., Alternaria alternate Y-4-2) associated with the title plant led to the isolation of 21 structurally distinct polyketides including one new dimeric xanthone (10). The new structures (1-10) with the absolute configurations were determined by detailed spectroscopic analyses, electronic circular dichroism (ECD) or Na2MoO4-induced ECD, the modified Mosher's method, and some chemical transformations. Compounds 1-4 are the first representatives of naturally occurring N-oxides of cephalotaxine esters, while compounds 7-9 have a special structural feature of having a C-methylated biflavonoid skeleton. The Cephalotaxus alkaloids with ester side-chains at C-3 (1-6, 13-22, and 26) and four biflavonoids (27-29 and 34) were found to show pronounced cytotoxicities against a small panel of human cancer cell lines (A549, NCI-H460, HL60, NCI-H929, and RPMI-8226), with IC50 values mainly ranging from 0.003 to 9.34 µM. The most potent compound, deoxyharringtonine (16), generally exhibited IC50 values less than 10 nM. The structure-activity relationship (SAR) of the aforementioned Cephalotaxus alkaloids was briefly discussed.

Small RNA-regulated expression of efflux pump affects tigecycline resistance and heteroresistance in clinical isolates of Klebsiella pneumoniae.

Tigecycline and the newly Food and Drug Administration-approved tetracyclines, including eravacycline and omadacycline, are regarded as last-resort treatments for multidrug-resistant Enterobacterales. However, tigecycline resistance in Klebsiella pneumoniae has increased, especially the underlying mechanism of heteroresistance is unclear. This study aimed to elucidate the mechanisms underlying tigecycline resistance and heteroresistance in clinical K. pneumoniae isolates. A total of 153 clinical K. pneumoniae isolates were collected, and identified 15 tigecycline-resistant and three tigecycline-heteroresistant isolates using broth microdilution and population analysis profile methods, respectively. Total RNAs from K. pneumoniae ATCC13883 and the laboratory-induced tigecycline-resistant strain were extracted and sequenced on an Illumina platform. Differentially expressed genes and regulatory small RNAs (sRNAs) were analyzed and validated in clinical isolates of K. pneumoniae using quantitative real-time PCR. RNA sequencing results showed that mdtABC efflux pump genes were significantly upregulated in the tigecycline-resistant strains. Overexpression of mdtABC was observed in a clinical K. pneumoniae isolate, which increased tigecycline minimum inhibitory concentrations (MICs) and was involved in tigecycline heteroresistance. Sequencing analysis of sRNA demonstrated that candidate sRNA-120 directly interacted with the mdtABC operon and was downregulated in tigecycline-resistant strains. We generated an sRNA-120 deletion mutation strain and a complemented strain of K. pneumoniae. The sRNA-120 deletion strain displayed increased mRNA levels of mdtA, mdtB, and mdtC and an increase in MICs of tigecycline. The complemented strain of sRNA-120 restored the mRNA levels of these genes and the susceptibility to tigecycline. RNA antisense purification and parallel reaction monitoring mass spectrometry were performed to verify the interactions between sRNA-120 and mdtABC. Collectively, our study highlights that the post-transcriptional repression of mdtABC through sRNA-120 may provide an additional layer of efflux pump gene expression control, which is important for resistance and heteroresistance in clinical K. pneumoniae isolates.

Function-oriented synthesis of Imidazo[1,2-a]pyrazine and Imidazo[1,2-b]pyridazine derivatives as potent PI3K/mTOR dual inhibitors.

The PI3K-Akt-mTOR signaling pathway is a highly frequently activated signal transduction pathway in human malignancies, which has been a hot target for anti-tumoral drug discovery. Based on our previous research, a function-oriented synthesis (FOS) of imidazo[1,2-a]pyrazines and imidazo[1,2-b]pyridazines was conducted, and their anticancer activities in vitro and in vivo were evaluated. Among them, compound 42 exhibited excellent dual PI3K/mTOR inhibitory activity, with IC50 values on PI3Kα and mTOR of 0.06 nM and 3.12 nM, respectively, much better than our previous reported compound 15a. Furthermore, compound 42 exhibited significant in vitro and in vivo anti-tumoral activities, great kinase selectivity, low hepatotoxicity, modest plasma clearance and acceptable oral bioavailability, which is a promising PI3K/mTOR targeted anti-cancer drug candidate.

Hepatic macrophage targeted siRNA lipid nanoparticles treat non-alcoholic steatohepatitis.

HMGB1 is an inflammatory factor produced by macrophages after liver injury, which plays a key role in promoting NASH progression and further developing into liver fibrosis and cirrhosis. In this study, a mannose-modified HMGB1-siRNA loaded stable nucleic acid lipid particle delivery system (mLNP-siHMGB1) was constructed to target liver macrophages with mannose receptor mediation, thereby silencing HMGB1 protein expression and treating NASH. We also examined the effect of co-administration with docosahexaenoic acid (DHA), a kind of unsaturated fatty acid, on NASH. The results showed that mLNP-siHMGB1 could target macrophages through mannose receptors, effectively silence HMGB1 gene, reduce the release of HMGB1 protein in the liver, regulate liver macrophages to be an anti-inflammatory M2 phenotype, effectively reduce hepatic lobular inflammation and bullous steatosis in the liver, and restore the liver function of NASH model mice to a normal level. After 8 weeks of combined treatment with mLNP-siHMGB1 and DHA, the liver function of NASH model mice recovered rapidly and the hepatic steatosis returned to normal level. In view of inflammation, a key factor in the progression of NASH, we provided an actively targeted siRNA delivery system in this study, and clarified the important role of the delivery system in phenotypic regulation of liver macrophages in NASH. In addition, we also demonstrated the effectiveness of DHA co-administration in NASH treatment. This study provided a useful idea and scientific basis for the development of therapeutic strategies for NASH in the future.

Novel 2-phenyl-3-(Pyridin-2-yl) thiazolidin-4-one derivatives as potent inhibitors for proliferation of osteosarcoma cells in vitro and in vivo.

Due to unknown pathogenesis and unidentified drug target, no drug for the treatment of osteosarcoma (OS) has been launched to the market. Herein, thiazolidinone 1a was discovered as a hit compound by phenotypic screening with an in-house patrimonial collection of structural diversity. The following SAR (Structure-Activity Relationship) study affords the final water-soluble lead compound (R)-8i as a potential inhibitor for the proliferation of OS cells by the modulation of solubility of the compounds with remarkable cellular potency (IC50 = 21.9 nM for MNNG/HOS cells) and in vivo efficacy (52.9% inhibition OS growth in mice), as well as pharmacokinetic properties. (R)-8i also significantly suppresses OS cell migration in vitro and showed to be well-tolerated. Our preliminary investigation shows that the effects of (R)-8i are not dependent on p53 and myoferlin (MYOF). These results suggest that (R)-8i might be a potential drug candidate for OS treatment.

Genetic diversity and co-prevalence of ESBLs and PMQR genes among plasmid-mediated AmpC ß-lactamase-producing Klebsiella pneumoniae isolates causing urinary tract infection.

Klebsiella pneumoniae is an opportunistic pathogen that frequently causes nosocomial urinary tract infection (UTI). The aim of this study was to investigate the prevalence of extended-spectrum ß-lactamases (ESBL), plasmid-mediated quinolone resistance (PMQR) genes, in acquired AmpC (ac-AmpC) ß­lactamase­producing K. pneumoniae isolates from patients with nosocomial UTI and to characterize the transmissibility of plasmids harbouring multiple resistance genes. From January 2017 to June 2018, we collected 46 ac-AmpC-producing K. pneumoniae isolates causing UTI from a tertiary care hospital in China. Antimicrobial susceptibility assays showed that non-susceptibility of all isolates to third-generation cephalosporin and fluoroquinolone was very high (>80%). Diverse types of ESBLs and PMQR genes, including blaSHV-12 (n = 23), blaSHV-27 (n = 1), blaSHV-28 (n = 2), blaSHV-33 (n = 4), blaCTX-M-3 (n = 24), blaCTX-M-14 (n = 6), blaCTX-M-15 (n = 6), blaCTX-M-22 (n = 1) and blaOXA-10 (n = 26), as well as qnrA (n = 2), qnrB (n = 39) and qnrS (n = 2) genes were identified amongst AmpC-producing K. pneumoniae isolates. The blaAmpC, qnrB and several ESBLs genes from six strains harbouring multiple AmpC (at least two ampC) were co-transferrable to recipients via conjugation or electroporation, with IncFIA, IncFIB and IncA/C being the dominant replicons. Conserved genetic context associated with the mobilization of blaampC genes was detected. Forty-six isolates were categorized into 25 enterobacterial repetitive intergenic consensus (ERIC) types, and the 6 isolates harbouring multiple AmpC genes belonged to ST1 lineage. This work reports that the emergence of plasmids co-harbouring multiple resistance determinants and mediating the local prevalence in K. pneumoniae causing UTI in China.

Impact of Carbapenem Heteroresistance Among Multidrug-Resistant ESBL/AmpC-Producing Klebsiella pneumoniae Clinical Isolates on Antibiotic Treatment in Experimentally Infected Mice.

PURPOSE: Antibiotic resistance is a growing health crisis that is further complicated by treatment failures caused by bacteria that exhibit heterogeneous susceptibility to antibiotics. The aim of this study was to describe imipenem (IPM)-heteroresistant strains among multidrug-resistant (MDR) ESBL/AmpC-producing Klebsiella pneumoniae clinical isolates, investigate their molecular phenotypic characteristics, and elucidate the outcome of antibiotic treatment in mice infected with the heteroresistant isolates. MATERIALS AND METHODS: Antimicrobial susceptibility of K. pneumoniae isolates was determined by the disk diffusion and E-test methods. Heteroresistance to IPM was confirmed by population analysis profile (PAP) assays. PCR and sequencing were employed to detect MDR determinants. Molecular differences between the susceptible and resistant subpopulations were evaluated by sequencing and quantitative real-time reverse transcription PCR (qRT-PCR) analysis. The effect of the carbapenem-heteroresistant strains on antibiotic treatment was assessed using a mouse model of peritonitis with heteroresistant K. pneumoniae and subsequent treatment with IPM. RESULTS: In total, 37 MDR ESBL/AmpC-producing clinical isolates of K. pneumoniae were identified between September 2018 and December 2019. These strains were notably resistant to conventional antimicrobials other than carbapenems. Among the isolates, three strains exhibited heteroresistance to IPM and carried several ESBL and/or AmpC genes. Mice infected with a lethal dose of any of the three heteroresistant isolates were unable to survive in the presence of IPM treatment, as the percentage of the IPM-resistant subpopulation of each strain was increased in the peritoneum of these mice at 24 h after infection. The resistant subpopulation of the strains presented pulsed-field gel electrophoresis (PFGE) profiles that were identical to those of the susceptible subpopulation, but ompK36 porin showed a reduction in gene expression (0.09- to 0.50-fold) in the resistant subpopulation. CONCLUSION: Carbapenem-heteroresistant strains were present among the MDR K. pneumoniae isolates producing ESBL/AmpC ß-lactamases, and these heteroresistant strains failed IPM therapy in experimentally infected mice.

Monocular Vision-Based Retinal Membrane Peeling With a Handheld Robot.

Retinal membrane peeling requires delicate manipulation. The presence of the surgeon's physiological tremor, the high variability and often low quality of the ophthalmic image, and excessive forces make the tasks more challenging. Preventing unintended movement caused by tremor and unintentional forces can reduce membrane injury. With the use of an actively stabilized handheld robot, we employ a monocular camera-based surface reconstruction method to estimate the retinal plane and we propose the use of a virtual fixture with the application of a hard stop and motion scaling to improve control of the tool tip during delaminating in a laboratory simulation of retinal membrane peeling. A hard stop helps to limit downward force exerted on the surface. Motion scaling also improves the user's control of contact force when delaminating. We demonstrate a reduction of maximum force and maximum surface-penetration distance from the estimated retinal plane using the proposed technique.

Role of miR-124 in the regulation of retinoic acid-induced Neuro-2A cell differentiation.

Retinoic acid can cause many types of cells, including mouse neuroblastoma Neuro-2A cells, to differentiate into neurons. However, it is still unknown whether microRNAs (miRNAs) play a role in this neuronal differentiation. To address this issue, real-time polymerase chain reaction assays were used to detect the expression of several differentiation-related miRNAs during the differentiation of retinoic acid-treated Neuro-2A cells. The results revealed that miR-124 and miR-9 were upregulated, while miR-125b was downregulated in retinoic acid-treated Neuro-2A cells. To identify the miRNA that may play a key role, miR-124 expression was regulated by transfection of miRNA mimics or inhibitors. Morphological analysis results showed that inhibition of miR-124 expression reversed the effects of retinoic acid on neurite outgrowth. Moreover, miR-124 overexpression alone caused Neuro-2A cells to differentiate into neurons, and its inhibitor could block this effect. These results suggest that miR-124 plays an important role in retinoic acid-induced differentiation of Neuro-2A cells.

Design, Synthesis, and Biological Evaluation of Imidazo[1,2-a]pyridine Derivatives as Novel PI3K/mTOR Dual Inhibitors.

PI3K-Akt-mTOR signaling pathway has been validated as an effective targeting pathway for cancer therapy. However, no PI3K/mTOR dual inhibitor has been approved by the FDA yet. Therefore, it is still essential to discover a candidate with good efficacy and low toxicity. In our design, a series of imidazo[1,2-a]pyridine derivatives had been synthesized and subjected to activity assessment in vitro and in vivo. 15a was proved to be a potent PI3K/mTOR dual inhibitor with excellent kinase selectivity, modest plasma clearance, and acceptable oral bioavailability. Besides, 15a displayed significant inhibition of tumor growth in HCT116 and HT-29 xenografts without obvious effect on body weight.

Synthesis and Anticancer Activity of Novel Actinonin Derivatives as HsPDF Inhibitors.

Human mitochondrial peptide deformylase (HsPDF) is responsible for removing the formyl group from N-terminal formylmethionines of newly synthesized mitochondrial proteins and plays important roles in maintaining mitochondria function. It is overexpressed in various cancers and has been proposed as a novel therapeutic target. Actinonin, a naturally occurring peptidomimetic HsPDF inhibitor, was reported to inhibit the proliferation of a broad spectrum of human cancer cells in vitro. However, its efficacy and pharmacokinetic profile requires significant improvement for therapeutic purposes. To obtain HsPDF inhibitors as anticancer therapeutics, we screened an in-house collection of actinonin derivatives and found two initial hits with antiproliferation activity. Further optimization along the peptidomimetic backbone lead to two series of compounds containing substituted phenyl moieties. They are potent HsPDF inhibitors and exhibited greatly improved antiproliferation activity in selected cancer cell lines. Finally, compound 15m significantly inhibited the growth of human colon cancer in xenograft animal models.