CXCR2, a novel target to overcome tyrosine kinase inhibitor resistance in chronic myelogenous leukemia cells

Chronic myeloid leukemia (CML) is a reciprocal translocation disorder driven by a breakpoint cluster region (BCR)-Abelson leukemia virus (ABL) fusion gene that stimulates abnormal tyrosine kinase activity. Tyrosine kinase inhibitors (TKIs) are effective in treating Philadelphia chromosome (Ph) + CML patients. However, the appearance of TKI-resistant CML cells is a hurdle in CML treatment. Therefore, it is necessary to identify novel alternative treatments targeting tyrosine kinases. This study was designed to determine whether C-X-C chemokine receptor 2 (CXCR2) could be a novel target for TKI-resistant CML treatment. Interleukin 8 (IL-8), a CXCR2 ligand, was significantly increased in the bone marrow serum of initially diagnosed CML patients and TKI-resistant CML cell conditioned media. CXCR2 antagonists suppressed the proliferation of CML cells via cell cycle arrest in the G2/M phase. CXCR2 inhibition also attenuated mTOR, c-Myc, and BCR-ABL expression, leading to CML cell apoptosis, irrespective of TKI responsiveness. Moreover, SB225002, a CXCR2 antagonist, caused higher cell death in TKI-resistant CML cells than TKIs. Using a mouse xenograft model, we confirmed that SB225002 suppresses tumor growth, with a prominent effect on TKI-resistant CML cells. Our findings demonstrate that IL-8 is a prognostic factor for the progression of CML. Inhibiting the CXCR2-mTOR-c-Myc cascade is a promising therapeutic strategy to overcome TKI-sensitive and TKI-insensitive CML. Thus, CXCR2 blockade is a novel therapeutic strategy to treat CML, and SB225002, a commercially available CXCR2 antagonist, might be a candidate drug that could be used to treat TKI-resistant CML.

An in vivo reporter for tracking lipid droplet dynamics in transparent zebrafish

Lipid droplets are lipid storage organelles found in nearly all cell types from adipocytes to cancer cells. Although increasingly implicated in disease, current methods to study lipid droplets in vertebrate models rely on static imaging or the use of fluorescent dyes, limiting investigation of their rapid in vivo dynamics. To address this, we created a lipid droplet transgenic reporter in whole animals and cell culture by fusing tdTOMATO to Perilipin-2 (PLIN2), a lipid droplet structural protein. Expression of this transgene in transparent casper zebrafish enabled in vivo imaging of adipose depots responsive to nutrient deprivation and high-fat diet. Simultaneously, we performed a large-scale in vitro chemical screen of 1280 compounds and identified several novel regulators of lipolysis in adipocytes. Using our Tg(-3.5ubb:plin2-tdTomato) zebrafish line, we validated several of these novel regulators and revealed an unexpected role for nitric oxide in modulating adipocyte lipid droplets. Similarly, we expressed the PLIN2-tdTOMATO transgene in melanoma cells and found that the nitric oxide pathway also regulated lipid droplets in cancer. This model offers a tractable imaging platform to study lipid droplets across cell types and disease contexts using chemical, dietary, or genetic perturbations.

Oxa Analogues of Nexturastat A Demonstrate Improved HDAC6 Selectivity and Superior Antileukaemia Activity

The acetylome is important for maintaining the homeostasis of cells. Abnormal changes can result in the pathogenesis of immunological or neurological diseases, and degeneration can promote the manifestation of cancer. In particular, pharmacological intervention in the acetylome with pan-histone deacetylase (HDAC) inhibitors is clinically validated. However, these drugs exhibit an undesirable risk-benefit profile due to severe side effects. Selective HDAC inhibitors might promote patient compliance and represent a valuable opportunity in personalised medicine. Therefore, we envisioned the development of HDAC6-selective inhibitors. During our lead structure identification, we demonstrated that an alkoxyurea-based connecting unit proves to be beneficial for HDAC6 selectivity and established the synthesis of alkoxyurea-based hydroxamic acids. Herein, we report highly potent N-alkoxyurea-based hydroxamic acids with improved HDAC6 preference compared to nexturastat A. We further validated the biological activity of these oxa analogues of nexturastat A in a broad subset of leukaemia cell lines and demonstrated their superior anti-proliferative properties compared to nexturastat A.

Inhibition of Carbonic Anhydrase IX Promotes Apoptosis through Intracellular pH Level Alterations in Cervical Cancer Cells

Carbonic anhydrase IX (CAIX) is a hypoxia-related protein that plays a role in proliferation in solid tumours. However, how CAIX increases proliferation and metastasis in solid tumours is unclear. The objective of this study was to investigate how a synthetic CAIX inhibitor triggers apoptosis in the HeLa cell line. The intracellular effects of CAIX inhibition were determined with AO/EB, AnnexinV-PI, and γ-H2AX staining; measurements of intracellular pH (pHi), reactive oxygen species (ROS), and mitochondrial membrane potential (MMP); and analyses of cell cycle, apoptotic, and autophagic modulator gene expression (Bax, Bcl-2, caspase-3, caspase-8, caspase-9, caspase-12, Beclin, and LC3), caspase protein level (pro-caspase 3 and cleaved caspase-3, -8, -9), cleaved PARP activation, and CAIX protein level. Sulphonamide CAIX inhibitor E showed the lowest IC50 and the highest selectivity index in CAIX-positive HeLa cells. CAIX inhibition changed the morphology of HeLa cells and increased the ratio of apoptotic cells, dramatically disturbing the homeostasis of intracellular pHi, MMP and ROS levels. All these phenomena consequent to CA IX inhibition triggered apoptosis and autophagy in HeLa cells. Taken together, these results further endorse the previous findings that CAIX inhibitors represent an important therapeutic strategy, which is worth pursuing in different cancer types, considering that presently only one sulphonamide inhibitor, SLC-0111, has arrived in Phase Ib/II clinical trials as an antitumour/antimetastatic drug.

Rebound increases in chemokines by CXCR2 antagonist in breast cancer can be prevented by PKCδ and PKCε activators

Activation of CXCR2 by chemokines such as CXCL1 and CXCL2 increases aggressiveness of breast cancer, inducing chemoresistance, hence CXCR2 antagonists are in clinical trials. We previously reported that inhibition of CXCR2 increases MIP-2 (CXCL2), which may inhibit anti-tumoral effects of CXCR2 antagonists. This seems to be due to inhibition of protein kinase C (PKC) by CXCR2 antagonist since specific inhibitor of PKC also enhances MIP-2 secretion. We here examined whether CXCR2 inhibitor also increases KC (CXCL1) secretion, ligand for CXCR2 involved in metastasis and PKC activators can prevent increases in chemokine secretion. We used SB 225002, which is a specific CXCR2 antagonist. The effects of PKC activators that have documented anti-tumoral effects and activates multiple isozymes of PKC such as Ingenol-3-angelate (I3A) and bryostatin-1 were examined here. In addition, FR236924, PKCε selective and 7α-acetoxy-6β-benzoyloxy-12-O-benzoylroyleanone (Roy-Bz), PKCδ selective activators were also tested. The effects of activators were determined using brain metastatic (4TBM) and heart metastatic (4THM) subset of 4T1 breast carcinoma cells because these aggressive carcinoma cells with cancer stem cell features secrete high levels of KC and MIP-2. Inhibition of CXCR-2 activity increased KC (CXCL1) secretion. PKC activators prevented SB225002-induced increases in KC and MIP-2 secretion. Different activators/modulators induce differential changes in basal and SB225002-induced chemokine secretion as well as cell proliferation and the activators that act on PKCδ and/or PKCε such as bryostatin 1, FR236924 and Roy-Bz are the most effective. These activators alone also decrease cell proliferation or chemokine secretion or both. Given the role of KC and MIP-2 in drug resistance including chemotherapeutics, activators of PKCε and PKCδ may prevent emerging of resistance to CXCR2 inhibitors as well as other chemotherapeutics.

Synergistic Pharmacodynamic Effects of Gemcitabine and Fibroblast Growth Factor Receptor Inhibitors on Pancreatic Cancer Cell Cycle Kinetics and Proliferation

Median survival of pancreatic ductal adenocarcinoma cancer (PDAC) is 6 months, with 9% 5-year survival. Standard-of-care gemcitabine (Gem) provides only modest survival benefits, and combination therapies integrating novel targeted agents could improve outcomes. Fibroblast growth factor (FGF) receptors (FGFRs) play important roles in PDAC growth and invasion. Therefore, FGFR inhibitors (FGFRi) merit further investigation. Efficacy of Gem combined with NVP-BGJ398, a pan-FGFRi, was investigated in multiple PDAC cell lines exposed to the drugs alone and combined. Cell cycle distribution and cell numbers were quantified over time. Two pharmacodynamic models were developed to investigate Gem/BGJ398 interactions quantitatively: a drug-mediated cell proliferation/death model, and a drug-perturbed cell cycle progression model. The models captured temporal changes in cell numbers, cell cycle progression, and cell death during drug exposure. Simultaneous fitting of all data provided reasonable parameter estimates. Therapeutic efficacy was then evaluated in a PDAC mouse model. Compared with Gem alone, combined Gem + FGFRi significantly downregulated ribonucleotide-diphosphate reductase large subunit 1 (RRM1), a gemcitabine resistance (GemR) biomarker, suggesting the FGFRi inhibited GemR emergence. The cell proliferation/death pharmacodynamic model estimated the drug interaction coefficient ψ death = 0.798, suggesting synergistic effects. The mechanism-based cell cycle progression model estimated drug interaction coefficient ψ cycle = 0.647, also suggesting synergy. Thus, FGFR inhibition appears to synergize with Gem in PDAC cells and tumors by sensitizing cells to Gem-mediated inhibition of proliferation and cell cycle progression. SIGNIFICANCE STATEMENT: An integrated approach of quantitative modeling and experimentation was employed to investigate the nature of fibroblast growth factor receptor inhibitor (FGFRi)/gemcitabine (Gem) interaction, and to identify mechanisms by which FGFRi exposure reverses Gem resistance in pancreatic cancer cells. The results show that FGFRi interacts synergistically with Gem to sensitize pancreatic cancer cells and tumors to Gem-mediated inhibition of proliferation and cell cycle progression. Thus, addition of FGFRi to standard-of-care Gem treatment could be a clinically deployable approach to enhance therapeutic benefit to pancreatic cancer patients.

A Novel Integrated Pharmacokinetic-Pharmacodynamic Model to Evaluate Combination Therapy and Determine In Vivo Synergism

Understanding pharmacokinetic (PK)-pharmacodynamic (PD) relationships is essential in translational research. Existing PK-PD models for combination therapy lack consideration of quantitative contributions from individual drugs, whereas interaction factor is always assigned arbitrarily to one drug and overstretched for the determination of in vivo pharmacologic synergism. Herein, we report a novel generic PK-PD model for combination therapy by considering apparent contributions from individual drugs coadministered. Doxorubicin (Dox) and sorafenib (Sor) were used as model drugs whose PK data were obtained in mice and fit to two-compartment model. Xenograft tumor growth was biphasic in mice, and PD responses were described by three-compartment transit models. This PK-PD model revealed that Sor (contribution factor = 1.62) had much greater influence on overall tumor-growth inhibition than coadministered Dox (contribution factor = 0.644), which explains the mysterious clinical findings on remarkable benefits for patients with cancer when adding Sor to Dox treatment, whereas there were none when adding Dox to Sor therapy. Furthermore, the combination index method was integrated into this predictive PK-PD model for critical determination of in vivo pharmacologic synergism that cannot be correctly defined by the interaction factor in conventional models. In addition, this new PK-PD model was able to identify optimal dosage combination (e.g., doubling experimental Sor dose and reducing Dox dose by 50%) toward much greater degree of tumor-growth inhibition (>90%), which was consistent with stronger synergy (combination index = 0.298). These findings demonstrated the utilities of this new PK-PD model and reiterated the use of valid method for the assessment of in vivo synergism. SIGNIFICANCE STATEMENT: A novel pharmacokinetic (PK)-pharmacodynamic (PD) model was developed for the assessment of combination treatment by considering contributions from individual drugs, and combination index method was incorporated to critically define in vivo synergism. A greater contribution from sorafenib to tumor-growth inhibition than that of coadministered doxorubicin was identified, offering explanation for previously inexplicable clinical observations. This PK-PD model and strategy shall have broad applications to translational research on identifying optimal dosage combinations with stronger synergy toward improved therapeutic outcomes.

P38 mitogen activated protein kinase inhibitor improves platelet in vitro parameters and in vivo survival in a SCID mouse model of transfusion for platelets stored at cold or temperature cycled conditions for 14 days

Platelets for transfusion are stored at room temperature (20-24°C) up to 7 days but decline in biochemical and morphological parameters during storage and can support bacterial proliferation. This decline is reduced with p38MAPK inhibitor, VX-702. Storage of platelets in the cold (4-6°C) can reduce bacterial proliferation but platelets get activated and have reduced circulation when transfused. Thermocycling (cold storage with brief periodic warm ups) reduces some of the effects of cold storage. We evaluated in vitro properties and in vivo circulation in SCID mouse model of human platelet transfusion of platelets stored in cold or thermocycled for 14 days with and without VX-702. Apheresis platelet units (N = 15) were each aliquoted into five storage bags and stored under different conditions: room temperature; cold temperature; thermocycled temperature; cold temperature with VX-702; thermocycled temperature with VX-702. Platelet in vitro parameters were evaluated at 1, 7 and 14 days. On day 14, platelets were infused into SCID mice to assess their retention in circulation by flow cytometry. VX-702 reduced negative platelet parameters associated with cold and thermocycled storage such as an increase in expression of activation markers CD62, CD63 and of phosphatidylserine (marker of apoptosis measured by Annexin binding) and lowered the rise in lactate (marker of increase in anaerobic metabolism). However, VX-702 did not inhibit agonist-induced platelet aggregation indicating that it does not interfere with platelet hemostatic function. In vivo, VX-702 improved initial recovery and area under the curve in circulation of human platelets infused into a mouse model that has been previously validated against a human platelet infusion clinical trial. In conclusion, inhibition of p38MAPK during 14-days platelet storage in cold or thermocycling conditions improved in vitro platelet parameters and platelet circulation in the mouse model indicating that VX-702 may improve cell physiology and clinical performance of human platelets stored in cold conditions.

A Soluble Epoxide Hydrolase Inhibitor, 1-TrifluoromethoxyPhenyl-3-(1-Propionylpiperidin-4-yl) Urea, Ameliorates Experimental Autoimmune Encephalomyelitis

Polyunsaturated fatty acids (PUFAs) are essential FAs for human health. Cytochrome P450 oxygenates PUFAs to produce anti-inflammatory and pain-resolving epoxy fatty acids (EpFAs) and other oxylipins whose epoxide ring is opened by the soluble epoxide hydrolase (sEH/Ephx2), resulting in the formation of toxic and pro-inflammatory vicinal diols (dihydroxy-FAs). Pharmacological inhibition of sEH is a promising strategy for the treatment of pain, inflammation, cardiovascular diseases, and other conditions. We tested the efficacy of a potent, selective sEH inhibitor, 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU), in an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). Prophylactic TPPU treatment significantly ameliorated EAE without affecting circulating white blood cell counts. TPPU accumulated in the spinal cords (SCs), which was correlated with plasma TPPU concentration. Targeted lipidomics in EAE SCs and plasma identified that TPPU blocked production of dihydroxy-FAs efficiently and increased some EpFA species including 12(13)-epoxy-octadecenoic acid (12(13)-EpOME) and 17(18)-epoxy-eicosatrienoic acid (17(18)-EpETE). TPPU did not alter levels of cyclooxygenase (COX-1/2) metabolites, while it increased 12-hydroxyeicosatetraenoic acid (12-HETE) and other 12/15-lipoxygenase metabolites. These analytical results are consistent with sEH inhibitors that reduce neuroinflammation and accelerate anti-inflammatory responses, providing the possibility that sEH inhibitors could be used as a disease modifying therapy, as well as for MS-associated pain relief.

The anti-angiogenic agent lenvatinib induces tumor vessel normalization and enhances radiosensitivity in hepatocellular tumors

The evaluation of angiogenesis inhibitors requires the analysis of the precise structure and function of tumor vessels. The anti-angiogenic agents lenvatinib and sorafenib are multi-target tyrosine kinase inhibitors that have been approved for the treatment of hepatocellular carcinoma (HCC). However, the different effects on tumor vasculature between lenvatinib and sorafenib are not well understood. In this study, we analyzed the effects of both drugs on vascular structure and function, including vascular normalization, and investigated whether the normalization had a positive effect on a combination therapy with the drugs and radiation using micro X-ray computed tomography with gold nanoparticles as a contrast agent, as well as immunohistochemical analysis and interstitial fluid pressure (IFP) measurement. In mice subcutaneously transplanted with mouse HCC cells, treatment with lenvatinib or sorafenib for 14 days inhibited tumor growth and reduced the tumor vessel volume density. However, analysis of integrated data on vessel density, rates of pericyte-covering and perfused vessels, tumor hypoxia, and IFP measured 4 days after drug treatment showed that treatment with 3 mg/kg of lenvatinib significantly reduced the microvessel density and normalized tumor vessels compared to treatment with 50 mg/kg of sorafenib. These results showed that lenvatinib induced vascular normalization and improved the intratumoral microenvironment in HCC tumors earlier and more effectively than sorafenib. Moreover, such changes increased the radiosensitivity of tumors and enhanced the effect of lenvatinib and radiation combination therapy, suggesting that this combination therapy is a powerful potential application against HCC.

Cereblon modulator CC-885 induces CRBN-dependent ubiquitination and degradation of CDK4 in multiple myeloma

Molecular glue degraders that hijack cellular E3 ubiquitin ligases to target disease-driven proteins for proteosome-dependent degradation are emerging as a promising treatment. Immunomodulatory drugs are classical molecular glue that bind to cereblon (CRBN) to repurpose the function of the CRL4(CRBN) E3 ubiquitin ligase and developed to treat various hematological malignancies. Recently, a novel cereblon modulator CC-885 was developed to elicit broad antitumor activity. Although the degradation of GSPT1 is essential for the broad in vitro antitumor activity of CC-885, it is unclear whether other neosubstrates also contribute to the pharmacological effects of CC-885, especially in multiple myeloma (MM). Here, we show that CC-885 treatment caused growth retardant of MM cells via impairment of cell cycle progression and cell death both in vitro and in vivo. Mechanically, CC-885 selectively induced the ubiquitination and degradation of CDK4 in MM cells in a CRBN-dependent manner. CC-885-mediated CDK4 destruction decreased the phosphorylation of the tumor suppressor retinoblastoma (RB) and prevented the expression of E2F downstream genes. Importantly, genetic ablation or pharmacological inhibition of CDK4 enhances CC-885-induced cytotoxicity in MM cells, suggesting CDK4 destruction contributed to the cytotoxicity of CC-885 in MM cells.

Sublethal Impacts of Novaluron on Tarnished Plant Bug (Hemiptera: Miridae) Adults

Tarnished plant bug, Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae), has become a primary pest of cotton in the Midsouthern United States. Insect growth regulators such as novaluron are an important part of L. lineolaris management. While novaluron is lethal to nymphs, it does not kill adults, so it has been used when nymphs are the primary stage present. However, cotton yield protection was observed from an application of novaluron when adults were the predominant stage present. To explain this, a series of studies were conducted to examine sublethal impacts of novaluron to L. lineolaris adults. Novaluron ingestion by adults reduced hatch rate and sometimes reduced oviposition rate. Ingestion by either males or females reduced hatch rates, but the reduction was greater from female exposure. Contact exposure of adults with novaluron residues within 1 d of application reduced hatch rate by about 50%, but the impact on oviposition was inconsistent. A field study showed reduced hatch rate from contact exposure to mixed-age natural populations, but the overall net reproductive rate was not reduced. Surface exposure of eggs to novaluron did not reduce hatch rate. Overall, exposure of tarnished plant bug adults to novaluron, regardless of adult age or exposure route, reduced egg viability. However, the impact on oviposition rate and net reproductive rate varied with adult age and exposure route. This understanding of sublethal impacts of novaluron, in addition to lethal impacts on nymphs, should be considered when choosing application times to maximize effects on L. lineolaris populations.

Reductive TCA cycle metabolism fuels glutamine- and glucose-stimulated insulin secretion

Metabolic fuels regulate insulin secretion by generating second messengers that drive insulin granule exocytosis, but the biochemical pathways involved are incompletely understood. Here we demonstrate that stimulation of rat insulinoma cells or primary rat islets with glucose or glutamine + 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (Gln + BCH) induces reductive, "counter-clockwise" tricarboxylic acid (TCA) cycle flux of glutamine to citrate. Molecular or pharmacologic suppression of isocitrate dehydrogenase-2 (IDH2), which catalyzes reductive carboxylation of 2-ketoglutarate to isocitrate, results in impairment of glucose- and Gln + BCH-stimulated reductive TCA cycle flux, lowering of NADPH levels, and inhibition of insulin secretion. Pharmacologic suppression of IDH2 also inhibits insulin secretion in living mice. Reductive TCA cycle flux has been proposed as a mechanism for generation of biomass in cancer cells. Here we demonstrate that reductive TCA cycle flux also produces stimulus-secretion coupling factors that regulate insulin secretion, including in non-dividing cells.

Concentration-QTc analysis of quizartinib in patients with relapsed/refractory acute myeloid leukemia

PURPOSE

This analysis evaluated the relationship between concentrations of quizartinib and its active metabolite AC886 and QT interval corrected using Fridericia's formula (QTcF) in patients with relapsed/refractory acute myeloid leukemia (AML) treated in the phase 3 QuANTUM-R study (NCT02039726).

METHODS

The analysis dataset included 226 patients with AML. Quizartinib dihydrochloride was administered as daily doses of 20, 30, and 60 mg. Nonlinear mixed-effects modeling was performed using observed quizartinib and AC886 concentrations and time-matched mean electrocardiogram measurements.

RESULTS

Observed QTcF increased with quizartinib and AC886 concentrations; the relationship was best described by a nonlinear maximum effect (Emax) model. The predicted mean increase in QTcF at the maximum concentration of quizartinib and AC886 associated with 60 mg/day was 21.1 ms (90% CI, 18.3-23.6 ms). Age, body weight, sex, race, baseline QTcF, QT-prolonging drug use, hypomagnesemia, and hypocalcemia were not significant predictors of QTcF. Hypokalemia (serum potassium < 3.5 mmol/L) was a statistically significant covariate affecting baseline QTcF, but no differences in ∆QTcF (change in QTcF from baseline) were predicted between patients with versus without hypokalemia at the same quizartinib concentration. The use of concomitant QT-prolonging drugs did not increase QTcF further.

CONCLUSION

QTcF increase was dependent on quizartinib and AC886 concentrations, but patient factors, including sex and age, did not affect the concentration-QTcF relationship. Because concomitant strong cytochrome P450 3A (CYP3A) inhibitor use significantly increases quizartinib concentration, these results support the clinical recommendation of quizartinib dose reduction in patients concurrently receiving a strong CYP3A inhibitor.

CLINICAL TRIAL REGISTRATION

NCT02039726 (registered January 20, 2014).

ADAMTSL5 is an epigenetically activated gene underlying tumorigenesis and drug resistance in hepatocellular carcinoma

BACKGROUND & AIMS

The tumour microenvironment shapes tumour growth through cellular communications that include both direct interactions and secreted factors. The aim of this study was to characterize the impact of the secreted glycoprotein ADAMTSL5, whose role in cancer has not been previously investigated, on hepatocellular carcinoma (HCC).

METHODS

ADAMTSL5 methylation status was evaluated through bisulfite sequencing, and publicly available data analysis. ADAMTSL5 RNA and protein expression were assessed in mouse models and HCC patient samples and compared to data from published datasets. Functional studies, including association of ADAMTSL5 depletion with responsiveness to clinically relevant drugs, were performed in cellular and in vivo models. Molecular alterations associated with ADAMTSL5 targeting were determined using proteomics, biochemistry, and reverse-transcription quantitative PCR.

RESULTS

Methylome analysis revealed hypermethylated gene body CpG islands at the ADAMTSL5 locus in both mouse and human HCC, correlating with higher ADAMTSL5 expression. ADAMTSL5 targeting interfered with tumorigenic properties of HCC cells in vitro and in vivo, whereas ADAMTSL5 overexpression conferred tumorigenicity to pre-tumoural hepatocytes sensitized to transformation by a modest level of MET receptor expression. Mechanistically, ADAMTSL5 abrogation led to a reduction of several oncogenic inputs relevant to HCC, including reduced expression and/or phosphorylation levels of receptor tyrosine kinases MET, EGFR, PDGFRβ, IGF1Rβ, or FGFR4. This phenotype was associated with significantly increased sensitivity of HCC cells to clinically relevant drugs, namely sorafenib, lenvatinib, and regorafenib. Moreover, ADAMTSL5 depletion drastically increased expression of AXL, accompanied by a sensitization to bemcentinib.

CONCLUSIONS

Our results point to a role for ADAMTSL5 in maintaining the function of key oncogenic signalling pathways, suggesting that it may act as a master regulator of tumorigenicity and drug resistance in HCC.

LAY SUMMARY

The environment of cancer cells has profound effects on establishment, progression, and response of a tumour to treatment. Herein, we show that ADAMTSL5, a protein secreted by liver cancer cells and overlooked in cancer so far, is increased in this tumour type, is necessary for tumour formation and supports drug resistance. Adamtsl5 removal conferred sensitivity of liver cancer cells to drugs used in current treatment. This suggests ADAMTSL5 as a potential marker in liver cancer as well as a possible drug target.

Mycobacterial Epoxide Hydrolase EphD Is Inhibited by Urea and Thiourea Derivatives

The genome of the human intracellular pathogen Mycobacterium tuberculosis encodes an unusually large number of epoxide hydrolases, which are thought to be involved in lipid metabolism and detoxification reactions needed to endure the hostile environment of host macrophages. These enzymes therefore represent suitable targets for compounds such as urea derivatives, which are known inhibitors of soluble epoxide hydrolases. In this work, we studied in vitro the effect of the thiourea drug isoxyl on six epoxide hydrolases of M. tuberculosis using a fatty acid substrate. We show that one of the proteins inhibited by isoxyl is EphD, an enzyme involved in the metabolism of mycolic acids, key components of the mycobacterial cell wall. By analyzing mycolic acid profiles, we demonstrate the inhibition of EphD epoxide hydrolase activity by isoxyl and two other urea-based inhibitors, thiacetazone and AU1235, inside the mycobacterial cell.

Regorafenib enhances antitumor immunity via inhibition of p38 kinase/Creb1/Klf4 axis in tumor-associated macrophages

BACKGROUND

Regorafenib and other multikinase inhibitors may enhance antitumor efficacy of anti-program cell death-1 (anti-PD1) therapy in hepatocellular carcinoma (HCC). Its immunomodulatory effects, besides anti-angiogenesis, were not clearly defined.

METHODS

In vivo antitumor efficacy was tested in multiple syngeneic liver cancer models. Murine bone marrow-derived macrophages (BMDMs) were tested in vitro for modulation of polarization by regorafenib and activation of cocultured T cells. Markers of M1/M2 polarization were measured by quantitative reverse transcription PCR (RT-PCR), arginase activity, flow cytometry, and ELISA. Knockdown of p38 kinase and downstream Creb1/Klf4 signaling on macrophage polarization were confirmed by using knockdown of the upstream MAPK14 kinase, chemical p38 kinase inhibitor, and chromatin immunoprecipitation.

RESULTS

Regorafenib (5 mg/kg/day, corresponding to about half of human clinical dosage) inhibited tumor growth and angiogenesis in vivo similarly to DC-101 (anti-VEGFR2 antibody) but produced higher T cell activation and M1 macrophage polarization, increased the ratio of M1/M2 polarized BMDMs and proliferation/activation of cocultured T cells in vitro, indicating angiogenesis-independent immunomodulatory effects. Suppression of p38 kinase phosphorylation and downstream Creb1/Klf4 activity in BMDMs by regorafenib reversed M2 polarization. Regorafenib enhanced antitumor efficacy of adoptively transferred antigen-specific T cells. Synergistic antitumor efficacy between regorafenib and anti-PD1 was associated with multiple immune-related pathways in the tumor microenvironment.

CONCLUSION

Regorafenib may enhance antitumor immunity through modulation of macrophage polarization, independent of its anti-angiogenic effects. Optimization of regorafenib dosage for rational design of combination therapy regimen may improve the therapeutic index in the clinic.

Therapeutic Potential of Regorafenib-A Multikinase Inhibitor in Pulmonary Hypertension

Pulmonary hypertension (PH) is characterized by a progressive elevation of mean arterial pressure followed by right ventricular failure and death. Previous studies have indicated that numerous inhibitors of receptor tyrosine kinase signaling could be either beneficial or detrimental for the treatment of PH. Here we investigated the therapeutic potential of the multi-kinase inhibitor regorafenib (BAY 73-4506) for the treatment of PH. A peptide-based kinase activity assay was performed using the PamStation^®12 platform. The 5-bromo-2′-deoxyuridine proliferation and transwell migration assays were utilized in pulmonary arterial smooth muscle cells (PASMCs). Regorafenib was administered to monocrotaline- and hypoxia-induced PH in rats and mice, respectively. Functional parameters were analyzed by hemodynamic and echocardiographic measurements. The kinase activity assay revealed upregulation of twenty-nine kinases in PASMCs from patients with idiopathic PAH (IPAH), of which fifteen were established as potential targets of regorafenib. Regorafenib showed strong anti-proliferative and anti-migratory effects in IPAH-PASMCs compared to the control PASMCs. Both experimental models indicated improved cardiac function and reduced pulmonary vascular remodeling upon regorafenib treatment. In lungs from monocrotaline (MCT) rats, regorafenib reduced the phosphorylation of c-Jun N-terminal kinase and extracellular signal-regulated kinase 1/2. Overall, our data indicated that regorafenib plays a beneficial role in experimental PH.

The reduction of lipid-sourced energy production caused by ATGL inhibition cannot be compensated by activation of HSL, autophagy, and utilization of other nutrients in fish

The adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL)-mediated lipolysis play important roles in lipid catabolism. ATGL is considered the central rate-limiting enzyme in the mobilization of fatty acids in mammals. Currently, severe fat accumulation has been commonly detected in farmed fish globally. However, the ATGL-mediated lipolysis and the potential synergy among ATGL, HSL, and autophagy, which is another way for lipid breakdown, have not been intensively understood in fish. In the present study, we added Atglistatin as an ATGL-specific inhibitor into the zebrafish diet and fed to the fish for 5 weeks. The results showed that the Atglistatin-treated fish exhibited severe fat deposition, reduced oxygen consumption, and fatty acid β-oxidation, accompanied with increased oxidative stress and inflammation. Furthermore, the Atglistatin-treated fish elevated total and phosphorylation protein expressions of HSL. However, the free fatty acids and lipase activities in organs were still systemically reduced in the Atglistatin-treated fish, and the autophagy marker LC3 was also decreased in the liver. On the other hand, glycogenolysis was stimulated but blood glucose was higher in the Atglistatin-treated fish. The transcriptomic analysis also provided the hint that the protein turnover efficiency in Atglistatin-treated fish was likely to be accelerated, but the protein content in whole fish was not affected. Taken together, ATGL plays crucial roles in energy homeostasis such that its inhibition causes loss of lipid-sourced energy production, which cannot be compensated by activation of HSL, autophagy, and utilization of other nutrients.

Targeting mTOR by CZ415 Suppresses Cell Proliferation and Promotes Apoptosis via Lipin-1 in Cervical Cancer In Vitro and In Vivo

CZ415, a novel inhibitor of mammalian target of rapamycin (mTOR) kinase, has demonstrated anti-tumor activity in several types of cancer. However, its biological function and underlying mechanism of action in cervical cancer (CC) have not been fully studied. Two CC cell lines (Hela and Siha) were treated with increasing concentrations of CZ415. Cell viability was tested with the CCK-8 assay, cell proliferation was determined by Edu staining and the colony formation assay, and apoptosis was determined by flow cytometry and Hoechst 33342 staining. Protein expression was evaluated by western blotting. A nude mouse xenograft model was used to confirm the anti-tumor activity of CZ415 in vivo. Hematoxylin and eosin (H&E) and immunohistochemistry (IHC) staining were performed on samples of tumor tissue. Results showed that CZ415 inhibited CC cell survival in a dose- and time-dependent manner, and 100 nanomolar and 48 h were the optimal conditions. In vitro and in vivo experiments showed that treatment with CZ415 significantly inhibited spheroid formation, cell proliferation, and tumor growth. Further studies showed that the anti-cancer effects of CZ415 were due to an induction of apoptosis, which was accompanied by an upregulation of Bax and downregulation of Bcl-2 through Lipin-1. CZ415 also reduced the levels of mTOR/STAT3 expression. However, these phenotypic changes were reversed by overexpression of Lipin-1. Our results suggest that the novel mTOR inhibitor CZ415 mediates tumor malignancy via Lipin-1 and might be useful for treating CC.

Regorafenib inhibits migration, invasion, and vasculogenic mimicry of hepatocellular carcinoma via targeting ID1-mediated EMT

Regorafenib is approved for patients with unresectable hepatocellular carcinoma (HCC) following sorafenib. However, the effect of regorafenib on HCC metastasis and its mechanism are poorly understood. Here, our data showed that regorafenib significantly restrained the migration, invasion and vasculogenic mimicry (VM) of HCC cells, and downregulated the expression of epithelial-to-mesenchymal transition (EMT)/VM-related molecules. Using RNA-seq and cellular thermal shift assays, we found that inhibitor of differentiation 1 (ID1) was a key target of regorafenib. In HCC tissues, the protein expression of ID1 was positively correlated with EMT and VM formation (CD34- /PAS+ ). Functionally, ID1 knockdown inhibited HCC cell migration, invasion, metastasis, and VM formation in vitro and in vivo, with upregulation of E-cadherin and downregulation of Snail and VE-cadherin. Moreover, Snail overexpression promoted the migration, invasion, and VM formation of ID1 knockdown cells. Snail knockdown reduced the migration, invasion, and VM formation of ID1 overexpression cells. Finally, regorafenib suppressed VM formation and decreased the expression of ID1, VE-cadherin and Snail in HCC PDX model. In conclusion, we manifested that regorafenib distinctly inhibited EMT in HCC cells via targeting ID1, leading to the suppression of cell migration, invasion and VM formation. These findings suggest that regorafenib may be developed as a suitable therapeutic agent for HCC metastasis.

STOML2 potentiates metastasis of hepatocellular carcinoma by promoting PINK1-mediated mitophagy and regulates sensitivity to lenvatinib

BACKGROUND

Dysregulation of both mitochondrial biogenesis and mitophagy is critical to sustain oncogenic signaling pathways. However, the mechanism of mitophagy in promoting hepatocellular carcinoma (HCC) progression remains poorly understood. In this study, we investigated the clinical significance and biological involvement of mitochondrial inner membrane protein STOML2 in HCC.

METHODS

STOML2 was identified by gene expression profiles of HCC tissues and was measured in tissue microarray and cell lines. Gain/loss-of-function experiment was applied to study the biological function of STOML2 in HCC. Flow cytometry, Western blotting, laser confocal microscopy, transmission electron microscopy, and co-immunoprecipitation were used to detect and analyze mitophagy. ChIP and luciferase reporter assay were conducted to evaluate the relationship between STOML2 and HIF-1α. The sensitivity to lenvatinib was assessed in HCC both in vitro and in vivo.

RESULTS

Increased expression of STOML2 was found in HCC compared with paired peritumoral tissues. It was more significant in HCC with metastasis and correlated with worse overall survival and higher probability of recurrence after hepatectomy. Upregulation of STOML2 accelerated HCC cells colony formation, migration and invasion. Mechanically, TCGA dataset-based analysis showed enrichment of autophagy-related pathways in STOML2 highly-expressed HCC. Next, STOML2 was demonstrated to interact and stabilize PINK1 under cellular stress, amplify PINK1-Parkin-mediated mitophagy and then promote HCC growth and metastasis. Most interestingly, HIF-1α was upregulated and transcriptionally increased STOML2 expression in HCC cells under the treatment of lenvatinib. Furthermore, higher sensitivity to lenvatinib was found in HCC cells when STOML2 was downregulated. Combination therapy with lenvatinib and mitophagy inhibitor hydroxychloroquine obtained best efficacy.

CONCLUSIONS

Our findings suggested that STOML2 could amplify mitophagy through interacting and stabilizing PINK1, which promote HCC metastasis and modulate the response of HCC to lenvatinib. Combinations of pharmacologic inhibitors that concurrently block both angiogenesis and mitophagy may serve as an effective treatment for HCC.

Combined 3-O-acetylbetulin treatment and carbonic anhydrase IX inhibition results in additive effects on human breast cancer cells

Hypoxia plays a key role in tumor progression and resistance to radiotherapy. Expression of the transmembrane-tethered enzyme carbonic anhydrase IX (CA IX) is strongly induced by hypoxia. High CA IX expression levels correlate with poor prognosis in cancer patients. Previously, we showed that the downregulation of CA IX expression by siRNA interference and the inhibition of CA IX activity results in increased cytotoxicity, inhibition of migration and radiosensitization of hypoxic cancer cells. Betulinic acid (BA) is a natural compound derived from birch bark. It has shown promising anti-tumor effects due to its cancer cell specific cytotoxic properties. We have shown that BA inhibits the HIF-1α pathway, resulting in apoptosis, inhibition of migration and enhanced cytotoxicity of breast cancer cells. In this study, we investigate the effects of the novel betulin derivative 3-O-acetylbetulin (3-AC) and carbonic anhydrase inhibitors (CAI) octyl disulfamate (OCT) or 4-(3-[4-fluorophenyl]ureido)benzenesulfonamide (SLC-0111), on cellular and radiobiological parameters in MDA-MB-231 and MCF-7 cells. Treatment with 3-AC or OCT alone only caused moderate cytotoxicity, reduction in cell migration, ROS production and DNA damage. However, the combined treatment with 3-AC and CAI strongly enhanced radiosensitivity, increased cytotoxicity, inhibited cell motility and enhanced DNA damage. Our findings suggest that the combination of two bioactive drugs 3-AC and a CAI, such as OCT or SLC-0111, could be a promising therapeutic approach for targeting hypoxic tumor cells.

Limited efficacy of lenvatinib in heavily pretreated anaplastic thyroid cancer: a French overview

Anaplastic thyroid cancer (ATC) is a rare lethal disease. Lenvatinib is an off-label therapeutic option for ATC in most countries, except in Japan. The aim of this multicenter retrospective survey was to analyze the efficacy and the toxicity profile of off-label lenvatinib treatment in all adults advanced ATC patients, in France. Of the 23 patients analysed (14 males; mean age 64 years), 15 were pure ATC and 8 were mixed tumors (i.e. with a differentiated or poorly differentiated component). Prior treatments included neck external beam irradiation in 74%, at least one line of chemotherapy in 22 cases, two lines of chemotherapy in 11 patients, other TKI in 4 cases. A central RECIST assessment was performed. Since lenvatinib initiation, median PFS was 2.7 months (95% CI; 1.9-3.5) and median OS was 3.1 months (95% CI; 0.6-5.5). OS was significantly longer in case of mixed tumors compared with pure ATC (6.3 vs 2.7 months, P = 0.026). Best tumor response was partial response in two cases and stable disease in seven. Clinical improvement was achieved in seven patients. Lethal adverse events occurred in three patients, consisting in haemoptysis in two cases and pneumothorax in one case. Among long-surviving ATC patients (>6 months), four underwent biopsy of distant metastasis, revealing poorly differentiated histology; three of them had initial mixed ATC histology. Efficacy of lenvatinib appears limited, although pure vs mixed ATC disclose differences in disease aggressiveness and treatment response. Long-surviving ATC patients might benefit from biopsy of persistent disease, searching for histological transition or molecular target.

Inhibition of ATGL in adipose tissue ameliorates isoproterenol-induced cardiac remodeling by reducing adipose tissue inflammation

Following cardiac injury, increased adrenergic drive plays an important role in compensating for reduced cardiac function. However, chronic excess adrenergic stimulation can be detrimental to cardiac pathophysiology and can also affect other organs including adipose tissue, leading to increased lipolysis. Interestingly, inhibition of adipose triglyceride lipase (ATGL), a rate-limiting enzyme in lipolysis, in adipocytes ameliorates cardiac dysfunction in a heart failure model. Thus, we investigated whether inhibition of adipocyte ATGL can mitigate the adverse cardiac effects of chronic adrenergic stimulation and explored the underlying mechanisms. To do this, isoproterenol (ISO) was continuously administered to C57Bl/6N mice for 2 wk with or without an ATGL inhibitor (Atglistatin). We found that Atglistatin alleviated ISO-induced cardiac remodeling and reduced ISO-induced upregulation of galectin-3, a marker of activated macrophages and a potent inducer of fibrosis, in white adipose tissue (WAT), heart, and the circulation. To test whether the beneficial effects of Atglistatin occur via inhibition of adipocyte ATGL, adipocyte-specific ATGL knockout (atATGL-KO) mice were utilized for similar experiments. Subsequently, the same cardioprotective effects of atATGL-KO following ISO administration were observed. Furthermore, Atglistatin and atATGL-KO abolished ISO-induced galectin-3 secretion from excised WAT. We further demonstrated that activation of cardiac fibroblasts by the conditioned media of ISO-stimulated WAT is galectin-3-dependent. In conclusion, the inhibition of adipocyte ATGL ameliorated ISO-induced cardiac remodeling possibly by reducing galectin-3 secretion from adipose tissue. Thus, inhibition of adipocyte ATGL might be a potential target to prevent some of the adverse effects of chronic excess adrenergic drive.NEW & NOTEWORTHY The reduction of lipolysis by adipocyte ATGL inhibition ameliorates cardiac remodeling induced by chronic β-adrenergic stimulation likely via reducing galectin-3 secretion from adipose tissue. Our findings highlight that suppressing lipolysis in adipocytes may be a potential therapeutic target for patients with heart failure whose sympathetic nervous system is activated. Furthermore, galectin-3 might be involved in the mechanisms by which excessive lipolysis in adipose tissues influences remote cardiac pathologies and thus warrants further investigation.