Inhibition of aortic allograft vasculopathy by local delivery of platelet-derived growth factor receptor tyrosine-kinase blocker AG-1295

A new molecular subclassification and in silico predictions for diagnosis and prognosis of papillary thyroid cancer by alternative splicing profile

Introduction: Papillary thyroid cancer (PTC) is the most common endocrine malignancy. However, different PTC variants reveal high heterogeneity at histological, cytological, molecular and clinicopathological levels, which complicates the precise diagnosis and management of PTC. Alternative splicing (AS) has been reported to be potential cancer biomarkers and therapeutic targets. Method: Here, we aim to find a more sophisticated molecular subclassification and characterization for PTC by integrating AS profiling. Based on six differentially expressed alternative splicing (DEAS) events, a new molecular subclassification was proposed to reclassify PTC into three new groups named as Cluster0, Cluster1 and Cluster2 respectively. Results: An in silico prediction was performed for accurate recognition of new groups with the average accuracy of 91.2%. Moreover, series of analyses were implemented to explore the differences of clinicopathology, molecular and immune characteristics across them. It suggests that there are remarkable differences among them, but Cluster2 was characterized by poor prognosis, higher immune heterogeneity and more sensitive to anti-PD1 therapy. The splicing correlation networks proved the complicated regulation relationships between AS events and splicing factors (SFs). An independent prognostic indicator for PTC overall survival (OS) was established. Finally, three compounds (orantinib, tyrphostin-AG-1295 and AG-370) were discovered to be the potential therapeutic agents. Discussion: Overall, the six DEAS events are not only potential biomarkers for precise diagnosis of PTC, but also the probable prognostic predictors. This research would be expected to highlight the effect of AS events on PTC characterization and also provide new insights into refining precise subclassification and improving medical therapy for PTC patients.

Tetrahydroquinoxalines induce a lethal evisceration phenotype in Haemonchus contortus in vitro

In the present study, the anthelmintic activity of a human tyrosine kinase inhibitor, AG-1295, and 14 related tetrahydroquinoxaline analogues against Haemonchus contortus was explored. These compounds were screened against parasitic larvae - exsheathed third-stage (xL3) and fourth-stage (L4) - using a whole-organism screening assay. All compounds were shown to have inhibitory effects on larval motility, development and growth, and induced evisceration through the excretory pore in xL3s. The estimated IC₅₀ values ranged from 3.5 to 52.0 μM for inhibition of larval motility or development. Cytotoxicity IC₅₀ against human MCF10A cells was generally higher than 50 μM. Microscopic studies revealed that this eviscerated (Evi) phenotype occurs rapidly (<20 min) and relates to a protrusion of internal tissues and organs (evisceration) through the excretory pore in xL3s; severe pathological damage in L4s as well as a suppression of larval growth in both stages were also observed. Using a relatively low concentration (12.5 μM) of compound m10, it was established that the inhibitor has to be present for a relatively short time (between 30 h and 42 h) during in vitro development from xL3 to L4, to induce the Evi phenotype. Increasing external osmotic pressure prevented evisceration and moulting, and xL3s remained unaffected by the test compound. These results point to a mode of action involving a dysregulation of morphogenetic processes during a critical time-frame, in agreement with the expected behaviour of a tyrosine kinase inhibitor, and suggest potential for development of this compound class as nematocidal drugs.

•

Tetrahydroquinoxalines kill Haemonchus contortus larvae in vitro.

•

Compounds induce a lethal evisceration phenotype (Evi).

•

The Evi phenotype is associated with the timing of ecdysis.

•

These compounds might be developable as nematocidal drugs.

Screening of the 'Stasis Box' identifies two kinase inhibitors under pharmaceutical development with activity against Haemonchus contortus

Background

In partnership with the Medicines for Malaria Venture (MMV), we screened a collection (‘Stasis Box’) of 400 compounds (which have been in clinical development but have not been approved for illnesses other than neglected infectious diseases) for inhibitory activity against Haemonchus contortus, in order to attempt to repurpose some of the compounds to parasitic nematodes.

Methods

We assessed the inhibition of compounds on the motility and/or development of exsheathed third-stage (xL3s) and fourth-stage (L4) larvae of H. contortus using a whole-organism screening assay.

Results

In the primary screen, we identified compound MMV690767 (also known as SNS-032) that inhibited xL3 motility by ~70% at a concentration of 20 μM after 72 h as well as compound MMV079840 (also known as AG-1295), which induced a coiled xL3 phenotype, with ~50% inhibition on xL3 motility. Subsequently, we showed that SNS-032 (IC₅₀ = 12.4 μM) and AG-1295 (IC₅₀ = 9.92 ± 1.86 μM) had a similar potency to inhibit xL3 motility. Although neither SNS-032 nor AG-1295 had a detectable inhibitory activity on L4 motility, both compounds inhibited L4 development (IC₅₀ values = 41.24 μM and 7.75 ± 0.94 μM for SNS-032 and AG-1295, respectively). The assessment of the two compounds for toxic effects on normal human breast epithelial (MCF10A) cells revealed that AG-1295 had limited cytotoxicity (IC₅₀ > 100 μM), whereas SNS-032 was quite toxic to the epithelial cells (IC₅₀ = 1.27 μM).

Conclusions

Although the two kinase inhibitors, SNS-032 and AG-1295, had moderate inhibitory activity on the motility or development of xL3s or L4s of H. contortus in vitro, further work needs to be undertaken to chemically alter these entities to achieve the potency and selectivity required for them to become nematocidal or nematostatic candidates.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2246-x) contains supplementary material, which is available to authorized users.

Tyrosine kinase inhibitors: views of selectivity, sensitivity, and clinical performance

With the manufacture of imatinib, researchers introduced tyrosine kinase inhibitors (TKIs) into the clinical setting in 2000 to treat cancers; approximately fifteen other TKIs soon followed. Imatinib remains the most successful agent, whereas all the others have had modest effects on the cancers that they target. The current challenge is to identify the agents that need to be combined with TKIs to maximize their efficacy. One of the most promising approaches is to combine immune therapy with TKI treatment. In this review, the therapeutic potential of TKIs for treatment is discussed.

Targeting non-malignant disorders with tyrosine kinase inhibitors

Receptor and non-receptor tyrosine kinases are involved in multiple proliferative signalling pathways. Imatinib, one of the first tyrosine kinase inhibitors (TKIs) to be approved, revolutionized the treatment of chronic myelogenous leukaemia, and other TKIs with different spectra of kinase inhibition are used to treat renal cell carcinoma, non-small-cell lung cancer and colon cancer. Studies also support the potential use of TKIs as anti-proliferative agents in non-malignant disorders such as cardiac hypertrophy, and in benign-proliferative disorders including pulmonary hypertension, lung fibrosis, rheumatoid disorders, atherosclerosis, in-stent restenosis and glomerulonephritis. In this Review, we provide an overview of the most recent developments--both experimental as well as clinical--regarding the therapeutic potential of TKIs in non-malignant disorders.

Nicotinic and PDGF-receptor function are essential for nicotine-stimulated mitogenesis in human vascular smooth muscle cells

Cigarette smoking is implicated in the formation of occlusive vascular diseases. Nicotine's role in this process is incompletely understood. Nicotine's effect on human aortic vascular smooth muscle cells (HaVSMC) and the role of the nicotinic receptor (nAChR), platelet-derived growth factor (PDGF), and the PDGF-receptor (PDGF-R) in this response were studied. Nicotine's mitogenic effect was characterized by three methods: thymidine incorporation, a viability/proliferation assay based on metabolic conversion of tetrazolium salt to formazan dye and cell counting. Nicotine administration (10(-6) M) stimulated cell cycle entry marked by increased DNA synthesis, PCNA and cyclin D1 production, and increased cell division. Nicotinic receptor blockade with d-tubocurarine, a nicotinic AchR blocker, decreased nicotine-induced DNA synthesis, and cell division (0.33 +/- 0.04, 0.77 +/- 0.31-fold decrease, respectively). Nicotine increased cellular PDGF-BB transcript levels and protein release (ELISA: 1.6 +/- 0.5-fold increase) but not PDGF-AA or PDGF-AB release. Nicotine increased PDGFbeta-receptor protein content. PDGF inactivation with anti-PDGF antibody abolished nicotine-induced DNA synthesis (1.9 +/- 0.08-fold decrease). PDGF-R blockade with the PDGF-R antagonist tyrphostin AG 1295 decreased nicotine-induced DNA synthesis and cell division (0.25 +/- 0.01, 0.44 +/- 0.2-fold decrease, respectively). PDGF-R blockade reversed nicotine-stimulated increases in PDGF release, PDGF-BB transcripts, and PDGF-receptor levels (0.68 +/- 0.34; 0.46 +/- 0.01; 0.28 +/- 0.01-fold decrease, respectively). In conclusion, nicotine-mediated activation of nAChRs increases PDGF-BB transcription and protein production as well as PDGF beta-receptor levels. PDGF-BB/PDGF-R interaction is vital in nicotine's mitogenic actions on human aortic smooth muscle cells.

Appraisal of the extent of chronic allograft vasculopathy in animal models: Proposition of a standardized micromorphometric method

Arterial obstruction due to intimal myproliferation is an outcome used for investigating chronic allograft vasculopathy in animal models. Since harvested tissue may be distorted while processing, discrepancy may happen in the measure of the obstruction. We propose a standardized micromorphometric method for calculating the percentage of obstruction with eliminating the variability in the shape of the vessel cross-section. The mathematical adjustment avoids the overestimation of the percentage of obstruction and improves accuracy.

Effect of a Novel Inducible Nitric Oxide Synthase Inhibitor in Prevention of Rat Chronic Aortic Rejections

BACKGROUND

Cytotoxic nitric oxide (NO) is produced during ischemia-reperfusion injury and acute and chronic rejection in allografts by expression of inducible (i) NO synthase (NOS). Therefore, continuous inhibition of iNOS may prevent early graft dysfunction and immune injury (rejection) and consequently improve graft survival. FR260330 is a potent and selective inhibitor of iNOS activity that works by preventing iNOS monomers from dimerization. In this study, the authors evaluated the effect of FR260330 in prevention of chronic rejection in a model of rat aortic allografts.

METHODS

Male Lewis (LEW, RT1l) rats received male ACI (RT1a) aorta allografts or LEW aorta isografts. Fourteen groups (n > or = 6) were involved in this study. FR260330, tacrolimus, or both were administered orally for 14 or 90 days, according to protocol. The degree of intimal proliferation of graft aorta was determined by a computerized image system.

RESULTS

Both low and high doses of FR260330- or tacrolimus-treated grafts showed significantly decreased intima/(intima+media) ratios at day 90 compared with placebo controls. Combination therapy of low-dose FR260330 with low-dose tacrolimus produced a significant decrease of intima/(intima+media) ratios with intact endothelium compared with placebo controls. Anti-alpha-actin immunohistochemical staining demonstrated that one of the mechanisms of intimal proliferation is related to migration of vascular smooth muscle cells.

CONCLUSIONS

A selective inhibitor of NOS, FR260330 plays a protective role in chronic aortic allograft rejection in the rat. Combination therapy of low-dose FR260330 with tacrolimus produces significant protection of immune injury and may serve to improve long-term graft survival and function.

PDGF receptor kinase inhibitors for the treatment of PDGF driven diseases

PDGF and its receptors are involved in a variety of diseases: cancers, atherosclerosis, balloon injury induced restenosis, pulmonary fibrosis and more. In all cases enhanced signaling of the receptor is the hallmark. In some cases, like chronic monomyelocytic leukemia (CMML), the persistent PDGFR signaling is essential for the survival of the cancer cell. These findings induced the research community as well as the pharmaceutical industry to develop agents that block PDGFR signaling. The possible utilization of PDGFR kinase inhibitors as anti-restenosis agents is likely to move ahead of the utilization of these agents to treat human malignancies.

Tricyclic quinoxalines as potent kinase inhibitors of PDGFR kinase, Flt3 and Kit

Here we report on novel quinoxalines as highly potent and selective inhibitors of the type III receptor tyrosine kinases PDGFR, FLT3, and KIT. These compounds, tricyclic quinoxalines, were generated in order to improve bioavailability over the highly hydrophobic bicyclic quinoxalines. Four of the highly active compounds were characterized in detail and are shown to inhibit PDGFR kinase activity of the isolated receptor as well as in intact cells in the sub-micromolar concentration range. We show that the most active inhibitor (compound 13, AGL 2043) is approximately 15-20 times more potent than its isomer (compound 14, AGL 2044). We therefore compared the three dimensional structures of the two compounds by X-ray crystallography. These compounds are also highly effective in blocking the kinase activity of FLT3, KIT, and the oncogenic protein Tel-PDGFR in intact cells. These compounds are potent inhibitors of the proliferation of pig heart smooth muscle cells. They fully arrest the growth of these cells and the effect is fully reversible. The chemical, biochemical and cellular properties of these compounds as well as the solubility properties make them suitable for development as anti-restenosis and anti-cancer agents.