Promises and challenges: cabotegravir for preexposure prophylaxis.

PURPOSE OF REVIEW: Tenofovir-based oral PrEP has been effective in reducing population-level HIV incidence in multiple settings, although disparities remain. Injectable cabotegravir-based PrEP is an alternative that may be attractive to individuals with adherence challenges or who do not desire to take a daily medication. We review promises and challenges of cabotegravir-based PrEP. RECENT FINDINGS: Cabotegravir has demonstrated higher effectiveness than oral PrEP in two randomized trials, with a hazard ratio of 0.31 for HIV incidence among MSM and transgender women across multiple settings [95% confidence interval (CI) 0.18-0.62] and 0.11 for cisgender women in sub-Saharan Africa (95% CI 0.040.32). Cabotegravir was also highly effective among populations with disproportionate HIV incidence. Although cabotegravir breakthrough was rare, diagnosis was delayed with use of antigen/antibody-based HIV tests, and resistance occurred with breakthrough infections. Implementation will need to overcome several challenges, including HIV RNA laboratory monitoring not being widely available, requirement for additional staff time and clinic space, and need to provide oral medication during interruptions in dosing. SUMMARY: Cabotegravir-based PrEP is a highly effective additional PrEP option that will expand HIV prevention options. For successful roll-out, strategies for streamlined and accessible delivery of cabotegravir in real-world settings will need to be developed.

Efficacy of Plinabulin vs Pegfilgrastim for Prevention of Docetaxel-Induced Neutropenia in Patients With Solid Tumors: A Randomized Clinical Trial.

Importance: Prevention of chemotherapy-induced neutropenia (CIN) and its clinical consequences is an unmet need for which plinabulin, a selective immunomodulating microtubule-binding agent, is being tested. Objective: To demonstrate noninferiority between plinabulin and pegfilgrastim for days of severe neutropenia in cycle 1 in patients with solid tumors treated with docetaxel. Design, Setting, and Participants: The Plinabulin vs Pegfilgrastim for the Prevention of Docetaxel-Induced Neutropenia in Patients With Solid Tumors (PROTECTIVE-1) double-blind phase 3 randomized clinical trial was performed in multiple centers in China, Russia, Ukraine, and the US. Participants included patients with breast, prostate, or non-small cell lung cancer treated with single-agent docetaxel chemotherapy. Data were collected from June 1, 2018, to January 31, 2019. The database was locked on February 18, 2021. Data analysis was based on intention to treat and safety and performed from October 5, 2018, to February 23, 2021. Interventions: Plinabulin, 40 mg, plus placebo or pegfilgrastim, 6 mg, plus placebo. Main Outcomes and Measures: The primary end point was day of severe neutropenia in cycle 1. Additional end points included clinical consequences of CIN (febrile neutropenia, hospitalizations, infections, antibiotic use, and modifications of chemotherapy dose), patient-reported outcomes for bone pain score, markers for immune suppression (neutrophil-to-lymphocyte ratio [NLR] of >5), immature neutrophils (band, promyelocyte, and myelocyte counts >0), and safety. Results: Among the 105 patients included in the analysis (65 [6.19%] women; median age, 59 [range, 31-81] years), the primary end point was met within a noninferiority margin of 0.65 days, with a mean difference of 0.52 days (98.52% CI, 0.40-0.65 days). Grade 4 neutropenia frequency in cycle 1 was not significantly different. Plinabulin had earlier onset of action with less grade 4 neutropenia in week 1 of cycle 1. Plinabulin had fewer adverse clinical consequences with rates of febrile neutropenia (0 of 52 vs 1 of 53 [1.9%]), infections (4 of 52 [7.7%] vs 8 of 53 [15.1%]), chemotherapy dose delay of more than 7 days (2 of 52 [3.8%] vs 3 of 53 [5.7%]), and permanent chemotherapy discontinuation (7 of 52 [13.5%] vs 14 of 53 [26.4%]). Patients receiving plinabulin had significantly less bone pain (difference, -0.67 [95% CI, -1.17 to -0.16]; P = .01) and a better immunosuppressive profile (NLR >5 at day 8, 2 of 52 [3.8%] vs 24 of 51 [46.0%]; P < .001). Plinabulin was well tolerated, with comparable safety to pegfilgrastim. Conclusions and Relevance: Plinabulin has comparable efficacy to pegfilgrastim for the prevention of CIN, with better safety and a better immunosuppressive profile. Plinabulin's same-day dosing compared with pegfilgrastim's next-day dosing offers distinct advantages, including reducing use of health care services. Trial Registration: ClinicalTrials.gov Identifier: NCT03102606.

Quantum Mechanical-Based Stability Evaluation of Crystal Structures for HIV-Targeted Drug Cabotegravir.

The long-acting parenteral formulation of the HIV integrase inhibitor cabotegravir (GSK744) is currently being developed to prevent HIV infections, benefiting from infrequent dosing and high efficacy. The crystal structure can affect the bioavailability and efficacy of cabotegravir. However, the stability determination of crystal structures of GSK744 have remained a challenge. Here, we introduced an ab initio protocol to determine the stability of the crystal structures of pharmaceutical molecules, which were obtained from crystal structure prediction process starting from the molecular diagram. Using GSK744 as a case study, the ab initio predicted that Gibbs free energy provides reliable further refinement of the predicted crystal structures and presents its capability for becoming a crystal stability determination approach in the future. The proposed work can assist in the comprehensive screening of pharmaceutical design and can provide structural predictions and stability evaluation for pharmaceutical crystals.

Cyclic Dipeptides: The Biological and Structural Landscape with Special Focus on the Anti-Cancer Proline-Based Scaffold.

Cyclic dipeptides, also know as diketopiperazines (DKP), the simplest cyclic forms of peptides widespread in nature, are unsurpassed in their structural and bio-functional diversity. DKPs, especially those containing proline, due to their unique features such as, inter alia, extra-rigid conformation, high resistance to enzyme degradation, increased cell permeability, and expandable ability to bind a diverse of targets with better affinity, have emerged in the last years as biologically pre-validated platforms for the drug discovery. Recent advances have revealed their enormous potential in the development of next-generation theranostics, smart delivery systems, and biomaterials. Here, we present an updated review on the biological and structural profile of these appealing biomolecules, with a particular emphasis on those with anticancer properties, since cancers are the main cause of death all over the world. Additionally, we provide a consideration on supramolecular structuring and synthons, based on the proline-based DKP privileged scaffold, for inspiration in the design of compound libraries in search of ideal ligands, innovative self-assembled nanomaterials, and bio-functional architectures.

The Potential Impact of Long-Acting Cabotegravir for HIV Prevention in South Africa: A Mathematical Modeling Study.

BACKGROUND: Although effective, some oral pre-exposure prophylaxis (PrEP) users face barriers to adherence using daily pills, which could be reduced by long-acting formulations. Long-acting cabotegravir (CAB LA) is a potential new injectable formulation for human immunodeficiency virus (HIV) PrEP being tested in phase III trials. METHODS: We use a mathematical model of the HIV epidemic in South Africa to simulate CAB LA uptake by population groups with different levels of HIV risk. We compare the trajectory of the HIV epidemic until 2050 with and without CAB LA to estimate the impact of the intervention. RESULTS: Delivering CAB LA to 10% of the adult population could avert more than 15% of new infections from 2023 to 2050. The impact would be lower but more efficient if delivered to populations at higher HIV risk: 127 person-years of CAB LA use would be required to avert one HIV infection within 5 years if used by all adults and 47 person-years if used only by the highest risk women. CONCLUSIONS: If efficacious, a CAB LA intervention could have a substantial impact on the course of the HIV epidemic in South Africa. Uptake by those at the highest risk of infection, particularly young women, could improve the efficiency of any intervention.

Targeted inhibition of ERα signaling and PIP5K1α/Akt pathways in castration-resistant prostate cancer.

Selective ERα modulator, tamoxifen, is well tolerated in a heavily pretreated castration-resistant prostate cancer (PCa) patient cohort. However, its targeted gene network and whether expression of intratumor ERα due to androgen deprivation therapy (ADT) may play a role in PCa progression is unknown. In this study, we examined the inhibitory effect of tamoxifen on castration-resistant PCa in vitro and in vivo. We found that tamoxifen is a potent compound that induced a high degree of apoptosis and significantly suppressed growth of xenograft tumors in mice, at a degree comparable to ISA-2011B, an inhibitor of PIP5K1α that acts upstream of PI3K/AKT survival signaling pathway. Moreover, depletion of tumor-associated macrophages using clodronate in combination with tamoxifen increased inhibitory effect of tamoxifen on aggressive prostate tumors. We showed that both tamoxifen and ISA-2011B exert their on-target effects on prostate cancer cells by targeting cyclin D1 and PIP5K1α/AKT network and the interlinked estrogen signaling. Combination treatment using tamoxifen together with ISA-2011B resulted in tumor regression and had superior inhibitory effect compared with that of tamoxifen or ISA-2011B alone. We have identified sets of genes that are specifically targeted by tamoxifen, ISA-2011B or combination of both agents by RNA-seq. We discovered that alterations in unique gene signatures, in particular estrogen-related marker genes are associated with poor patient disease-free survival. We further showed that ERα interacted with PIP5K1α through formation of protein complexes in the nucleus, suggesting a functional link. Our finding is the first to suggest a new therapeutic potential to inhibit or utilize the mechanisms related to ERα, PIP5K1α/AKT network, and MMP9/VEGF signaling axis, providing a strategy to treat castration-resistant ER-positive subtype of prostate cancer tumors with metastatic potential.

Efficacy of Plinabulin vs Pegfilgrastim for Prevention of Chemotherapy-Induced Neutropenia in Adults With Non-Small Cell Lung Cancer: A Phase 2 Randomized Clinical Trial.

IMPORTANCE: Plinabulin is a novel, non-granulocyte colony-stimulating factor (GCSF) small molecule with both anticancer and neutropenia-prevention effects. OBJECTIVE: To assess the efficacy and safety of plinabulin compared with pegfilgrastim for the prevention of chemotherapy-induced neutropenia following docetaxel chemotherapy in patients with non-small lung cancer. DESIGN, SETTING, AND PARTICIPANTS: This was a randomized, open-label, phase 2 clinical trial of 4 treatment arms that was conducted in 19 cancer treatment centers in the United States, China, Russia, and Ukraine. Participants were adult patients with non-small cell lung cancer whose cancer had progressed after platinum-based chemotherapy. Data were collected from April 2017 through March 2018 and analyzed from August 2019 through February 2020. INTERVENTIONS: All patients received docetaxel 75 mg/m2 on day 1 and were randomly assigned to 1 of 3 doses of plinabulin (5, 10, or 20 mg/m2) on day 1 or to pegfilgrastim 6 mg on day 2. Patients were treated every 21 days for 4 chemotherapy cycles. MAIN OUTCOMES AND MEASURES: The primary end point was the determination of the recommended phase 3 dose of plinabulin based on the days of severe neutropenia during chemotherapy cycle 1. Daily complete blood cell counts and absolute neutrophil counts were drawn during times of anticipated neutropenia during cycle 1. RESULTS: Of the 55 patients randomized and evaluated, the mean (SD) age was 61.3 (10.2) years, and 38 (69.1%) were men. With each escalation of the plinabulin dose, the incidence of any grade of neutropenia decreased. There were no significant differences in mean (SD) days of severe neutropenia among those treated with pegfilgrastim (0.15 [0.38] days) when dosed at day 2 vs plinabulin 20 mg/m2 (0.36 [0.93] days; P = .76) when dosed at day 1, and no safety signals were detected. CONCLUSIONS AND RELEVANCE: Single dose-per-cycle plinabulin has a similar neutropenia protection benefit as pegfilgrastim. Plinabulin 40 mg fixed dose, which is pharmacologically equivalent to 20 mg/m2, will be compared with pegfilgrastim 6 mg in the phase 3 portion of this trial. Noninferior days of severe neutropenia will be the primary end point, and bone pain reduction, thrombocytopenia reduction, and quality of life maintenance will be secondary end points. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03102606.

Discovery of novel (6S/12aS)-heptachpyridone capable of inhibiting thrombosis in vivo.

The in vitro conversion of (1S,3S)-1-dimethoxylethyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid, (1S,3S)-DCCA, in rat plasma is monitored by HPLC-FT-ICR-MS. We show that the in vitro conversion of (1S,3S)-DCCA in rat plasma for 1 h leads to forming (6S/12aS)-bisdimethoxyethylheptachpyridone, reflecting intermolecular condensation of (1S,3S)-DCCA, and the in vitro conversion of (6S/12aS)-bisdimethoxyethylheptachpyridone in rat plasma for 1 h leads to forming (6S/12aS)-heptachpyridone, reflecting hydrolysis of (6S/12aS)-bisdimethoxyethylheptachpyridone. At a dose of 1.0 µmol/kg (6S/12aS)-heptachpyridone orally inhibits venous thrombosis and arterial thrombosis in vivo. Bleeding time, clotting time and international normalized ratio show that at this dose (6S/12aS)-heptachpyridone has no bleeding risk, does not lengthen clotting time and does not change the exogenous coagulation pathway. We also show that the reactions promoted by rat plasma are easy to practice by chemical synthesis. Thus our findings build a bridge across the in vivo conversion and the application.

Functionally Selective Inhibition of the Oxytocin Receptor by Retosiban in Human Myometrial Smooth Muscle.

Novel small molecule inhibitors of the oxytocin receptor (OTR) may have distinct pharmacology and mode of action when compared with first-generation oxytocin antagonists when used for the prevention of preterm birth. The aim was to determine the mechanism of action of small molecule OTR antagonists retosiban and epelsiban compared with the currently used peptide-based compound atosiban. Human myometrial samples were obtained at cesarean section and subjected to pharmacological manipulations to establish the effect of antagonist binding to OTR on downstream signaling. Retosiban antagonism of oxytocin action in human myometrium was potent, rapid, and reversible. Inhibition of inositol 1,4,5-trisphosphate (IP3) production followed single-site competitive binding kinetics for epelsiban, retosiban, and atosiban. Retosiban inhibited basal production of IP3 in the absence of oxytocin. Oxytocin and atosiban but not retosiban inhibited forskolin, and calcitonin stimulated 3',5'-cyclic adenosine 5'-mono-phosphate (cAMP) production. Inhibition of cAMP was reversed by pertussis toxin. Oxytocin and atosiban, but not retosiban and epelsiban, stimulated extracellular regulated kinase (ERK)1/2 activity in a time- and concentration-dependent manner. Oxytocin and atosiban stimulated cyclo-oxygenase 2 activity and subsequent production of prostaglandin E2 and F2α. Prostaglandin production was inhibited by rofecoxib, pertussin toxin, and ERK inhibitor U0126. Oxytocin but not retosiban or atosiban stimulated coupling of the OTR to Gα q G-proteins. Oxytocin and atosiban but not retosiban stimulated coupling of the OTR to Gα i G-proteins. Retosiban and epelsiban demonstrate distinct pharmacology when compared with atosiban in human myometrial smooth muscle. Atosiban displays agonist activity at micromolar concentrations leading to stimulation of prostaglandin production.

Polymorphs, co-crystal structure and pharmacodynamics study of MBRI-001, a deuterium-substituted plinabulin derivative as a tubulin polymerization inhibitor.

MBRI-001, a deuterium-substituted plinabulin derivative, has been reported to have better pharmacokinetic and similar antitumor effects in comparison with plinabulin. In this approach, we further carried out its polymorphs, co-crystal structure of MBRI-001-tubulin and tubulin inhibition study. Among the different polymorphs, Form F (MBRI-001/H2O) was prepared and evaluated, which had better physical stability and suitable process for scale-up production. Co-crystal structure of MBRI-001-tubulin (PDB:5XI5) was prepared and analyzed. The result of tubulin polymerization assay demonstrated that MBRI-001 could inhibit tubulin polymerization which was similar as plinabulin. Subsequently, the anti-proliferative activities of plinabulin and MBRI-001 were evaluated against two different human lung cancer cell lines. In vivo study, MBRI-001 revealed similar antitumor inhibition in comparison with plinabulin in A549 xenograft tumor model. Therefore, we suggested that MBRI-001 could be developed as a promising anti-cancer agent in near future.

The role of PIP5K1α/pAKT and targeted inhibition of growth of subtypes of breast cancer using PIP5K1α inhibitor.

Despite recent improvement in adjuvant therapies, triple-negative, and ER+ subtypes of breast cancer (BC) with metastatic potentials remain the leading cause of BC-related deaths. We investigated the role of phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5Kα), a key upstream factor of PI3K/AKT, and the therapeutic effect of PIP5Kα inhibitor on subtypes of BC. The clinical importance of PIP5K1α and its association with survivals were analyzed using three BC cohorts from Nottingham (n = 913), KM plotter (n = 112) and TCGA (n = 817). Targeted overexpression or knockdown of PIP5K1α were introduced into BC cell lines. The effects of PIP5K1α and its inhibitor on growth and invasion of BC were confirmed by using in vitro assays including proliferation, migration, apoptosis and luciferase reporter assays and in vivo xenograft mouse models. All statistical tests were two-sided. PIP5K1α was associated with poor patient outcome in triple-negative BC (for PIP5K1α protein, p = 0.011 and for mRNA expression, p = 0.028, log-rank test). 29% of triple-negative BC had PIP5K1A gene amplification. Elevated level of PIP5K1α increased expression of pSer-473 AKT (p < 0.001) and invasiveness of triple-negative MDA-MB-231 cells (p < 0.001). Conversely, inhibition of PIP5K1α using its inhibitor ISA-2011B, or via knockdown suppressed growth and invasiveness of MDA-MB-231 xenografts (mean vehicle-treated controls = 2160 mm3, and mean ISA-2011B-treated = 600 mm3, p < 0.001). ISA-2011B-treatment reduced expression of pSer-473 AKT (p < 0.001) and its downstream effectors including cyclin D1, VEGF and its receptors, VEGFR1 and VEGFR2 (p < 0.001) in xenograft tumors. In ER+ cancer cells, PIP5K1α acted on pSer-473 AKT, and was in complexes with VEGFR2, serving as co-factor of ER-alpha to regulate activities of target genes including cyclin D1 and CDK1. Our study suggests that our developed PIP5K1α inhibitor has a great potential on refining targeted therapeutics for treatment of triple-negative and ER+ BC with abnormal PI3K/AKT pathways.

Biological profiling of piperazinediones for the management of anxiety.

The anxiolytic effect of earlier reported piperazinediones was assessed by elevated plus maze (EPM), hole-board and open-field (OFT) tests. The rats were administered pretreatment of three different doses i.e. 2, 1 and 0.5 mg/kg of compounds 52, 53 and 55 for seven consecutive days. Compound 52 and diazepam showed increase in open arm entries, increase in time spent therein and total arm entries at 1 mg/kg dose. The compound also produced increase in the number of head dip, sniffing behavior and total number of squares crossed compared to diazepam. In OFT paradigm grooming behavior, number of central squares crossed and the time spent in central area did not reveal statistical differences for diazepam and compound 52 at 1 mg/kg dose. Flumazenil mediated antagonism experiments of these showed that they were acting through benzodiazepine site on GABAA receptor. The levels of 5HT and 5HIAA were estimated in amygdalar region. Level of 5HT was found to be equivalent in case of compound 52 and diazepam treatment at dose of 1 mg/kg. Interestingly, compound 52 did not display sedative effect at higher dose in both animal models. Thus, present study indicated that compound 52 produced anti-anxiety property through modulation of GABAergic transmission.

In vitro and in vivo pharmacokinetic and pharmacodynamic study of MBRI-001, a deuterium-substituted plinabulin derivative as a potent anti-cancer agent.

MBRI-001 was demonstrated preliminary better pharmacokinetics and antitumor effects than that of plinabulin in vivo. In this approach, we further carried out systematic pharmacokinetic and pharmacodynamic study of MBRI-001 in vitro and in vivo. MBRI-001 was tested stable in rat plasma and more stable in liver microsomes than plinabulin in vitro. In vivo, MBRI-001 could be distributed rapidly and widely in various tissues, especially the concentration of MBRI-001 in lung was remarkably higher than other tissues. Excretion study indicated that MBRI-001 might been decomposed and excreted as metabolites. Additionally, the combination treatment of MBRI-001 and gefitinib revealed better antitumor inhibition rate than monotherapy in vivo. Therefore, we suggest that MBRI-001 could be developed as a promising anti-cancer agent in near future.

Antitumor activity of the microtubule inhibitor MBRI-001 against human hepatocellular carcinoma as monotherapy or in combination with sorafenib.

PURPOSE: MBRI-001 is a novel synthetic derivative of plinabulin. In this study, our purpose is to investigate the inhibition effects of MBRI-001 on human hepatocellular carcinoma as monotherapy or in combination with sorafenib. METHODS: HCCLM3 and Bel-7402 cell lines were used for activity evaluation in vitro. The anti-proliferative activity of MBRI-001 was assessed by MTT assay. The morphological change of microtubules was determined by immunofluorescence assay. The cell cycle was measured by flow cytometer. The expression of cyclin B1 (CCNB1) was analyzed by RT-qPCR and western blotting assays. The antitumor activities in vivo were evaluated with human HCC xenograft mice model. RESULTS: Our data demonstrated that MBRI-001 had better anti-proliferative activities than that of plinabulin against HCCLM3 and Bel-7402 cell lines. MBRI-001 inhibited the formation of microtubules and induced G2/M arrest with the downregulation of CCNB1. In vivo orthotopic mice model demonstrated that MBRI-001 significantly inhibited the growth of HCCLM3 with the apoptosis and necrosis observed in tumor. The combination treatment of MBRI-001 with sorafenib in subcutaneous mice model exhibited a higher antitumor inhibition rate at 72.0%, in comparison with MBRI-001 or sorafenib as monotherapy at 40.7% or 47.7%, respectively. CONCLUSION: MBRI-001 had better inhibition effects on microtubules and human hepatocellular carcinoma than that of plinabulin. The combination treatment of MBRI-001 and sorafenib exhibited a higher antitumor effect, which could provide a new strategy to treat HCC in the future.

Preclinical absorption, distribution, metabolism, excretion and pharmacokinetics of a novel selective inhibitor of breast cancer resistance protein (BCRP).

1. Breast cancer resistance protein (BCRP) plays an important role in drug absorption, distribution and excretion. It is challenging to evaluate BCRP functions in preclinical models because commonly used BCRP inhibitors are nonspecific or unstable in animal plasma. 2. In this work, in vitro absorption, distribution, metabolism and elimination (ADME) assays and pharmacokinetic (PK) experiments in Bcrp knockout (KO) (Abcg2-/-) and wild-type (WT) FVB mice and Wistar rats were conducted to characterize the preclinical properties of a novel selective BCRP inhibitor (ML753286, a Ko143 analog). 3. ML753286 is a potent inhibitor for BCRP, but not for P-glycoprotein (P-gp), organic anion-transporting polypeptide (OATP) or major cytochrome P450s (CYPs). It has high permeability, but is not an efflux transporter substrate. ML753286 has low to medium clearance in rodent and human liver S9 fractions, and is stable in plasma cross species. Bcrp inhibition affects oral absorption and clearance of sulfasalazine in rodents. A single dose of ML753286 at 50-300 mg/kg orally, and at 20 mg/kg intravenously or 25 mg/kg orally inhibits Bcrp functions in mice and rats, respectively. 4. These findings confirm that ML753286 is a useful selective inhibitor to evaluate BCRP/Bcrp activity in vitro and in rodent model systems.

Inhibitory Effect of Three Diketopiperazines from Marine-Derived Bacteria on HMGB1-Induced Septic Responses in Vitro and in Vivo.

The nucleosomal protein high-mobility group box-1 (HMGB1), which has recently been established as a late mediator of lethal systemic inflammation, has a relatively wide therapeutic window for pharmacological interventions. Compounds produced by marine-derived microbes have been widely investigated for their potential use as bioactive natural products. Cyclic dipeptides, which are also known as diketopiperazines, are molecules that are frequently found in marine-derived microorganisms. While their pharmacological potential has been well established, their biological activities against septic responses have not yet been reported. Here, three diketopiperazines (1-3) isolated from two strains of marine-derived bacteria were investigated for their potential activities against HMGB1-mediated septic responses. The data showed that 1-3 effectively inhibited the lipopolysaccharide (LPS)-induced release of HMGB1 and suppressed the HMGB1-mediated septic responses, including hyperpermeability, leukocyte adhesion and migration, and cell adhesion molecule expression. In addition, 1-3 inhibited the HMGB1-mediated production of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text] and interleukin (IL)-6 and the activation of nuclear factor-[Formula: see text]B (NF-[Formula: see text]B) and extracellular signal-regulated kinase (ERK) 1 and ERK2. Collectively, these results indicated that 1-3 might act as potential therapeutic agents for various severe vascular inflammatory diseases through the inhibition of the HMGB1 signaling pathway.

Suppressive effects of three diketopiperazines from marine-derived bacteria on polyphosphate-mediated septic responses.

Diketopiperazine is a natural products found from bacteria, fungi, marine sponges, gorgonian and red algae. They are cyclic dipeptides possessing relatively simple and rigid structures with chiral nature and various side chains. The compounds in this structure class have been known to possess diverse bioactivities including antibiotic activity, anti-cancer activity, neuroprotective activity, and anti-inflammatory activity. Previous studies have reported proinflammatory responses of endothelial cells to the release of polyphosphate (PolyP). In this study, we examined the anti-inflammatory responses and mechanisms of diketopiperazine and its effects on PolyP-induced septic activities in human umbilical vein endothelial cells (HUVECs) and mice. The survival rates, septic biomarker levels, behavior of human neutrophils, and vascular permeability were determined in PolyP-activated HUVECs and mice. Diketopiperazine suppressed the PolyP-mediated vascular barrier permeability, upregulation of inflammatory biomarkers, adhesion/migration of leukocytes, and activation and/or production of nuclear factor-κB, tumor necrosis factor-α, and interleukin-6. Furthermore, diketopiperazine demonstrated protective effects on PolyP-mediated lethal death and the levels of the related septic biomarkers. Therefore, these results indicated the therapeutic potential of diketopiperazine on various systemic inflammatory diseases, such as sepsis or septic shock.

TW-01, a piperazinedione-derived compound, inhibits Ras-mediated cell proliferation and angioplasty-induced vascular restenosis.

PURPOSE: Vascular smooth muscle cell (VSMC) proliferation plays a critical role in the pathogenesis of atherosclerosis and restenosis. This study investigated piperazinedione derived compound TW-01-mediated inhibitory effects on VSMC proliferation and intimal hyperplasia. METHODS: Cell proliferation was determined using [(3)H]-thymidine incorporation and MTT assay; cell cycle distribution was measured using flow cytometry; proteins and mRNA expression were determined using western blotting and RT-PCR analyses; DNA binding activity of nuclear factor-κB (NF-κB), as measured using enzyme-linked immunosorbent assays (ELISA); in vivo effects of TW-01 were determined using balloon angioplasty in the rat. RESULTS: TW-01 significantly inhibited cell proliferation. At the concentrations used, no cytotoxic effects were observed. Three predominant signaling pathways were inhibited by TW-01: (a) extracellular signal-regulated kinase (ERK)1/2 mitogen-activated protein kinase (MAPK) activation and its downstream effectors of c-fos, c-jun, and c-myc; (b) DNA binding activity of nuclear factor-κB (NF-κB); and, (c) Akt/protein kinase B (PKB) and cell cycle progression. Furthermore, TW-01 also inhibited Ras activation, a shared upstream event of each of these signaling cascades. In vascular injury studies, oral administration of TW-01 significantly suppressed intimal hyperplasia induced by balloon angioplasty. CONCLUSION: The present study suggests that TW-01 might be a potential candidate for atherosclerosis treatment.