1
|
Branchford BR, Stalker TJ, Law L, Acevedo G, Sather S, Brzezinski C, Wilson KM, Minson K, Lee-Sherick AB, Davizon-Castillo P, Ng C, Zhang W, Neeves KB, Lentz SR, Wang X, Frye SV, Shelton Earp H, DeRyckere D, Brass LF, Graham DK, Di Paola JA. The small-molecule MERTK inhibitor UNC2025 decreases platelet activation and prevents thrombosis. J Thromb Haemost 2018; 16:352-363. [PMID: 29045015 PMCID: PMC5858881 DOI: 10.1111/jth.13875] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Indexed: 02/06/2023]
Abstract
Essentials Signaling by Gas6 through Tyro3/Axl/Mer receptors is essential for stable platelet aggregation. UNC2025 is a small molecule inhibitor of the Mer tyrosine kinase. UNC2025 decreases platelet activation in vitro and thrombus formation in vivo. UNC2025's anti-platelet effect is synergistic with inhibition of the ADP receptor, P2Y12 . SUMMARY Background Growth arrest-specific protein 6 signals through the TAM (TYRO-3-AXL-MERTK) receptor family, mediating platelet activation and thrombus formation via activation of the aggregate-stabilizing αIIb β3 integrin. Objective To describe the antithrombotic effects mediated by UNC2025, a small-molecule MERTK tyrosine kinase inhibitor. Methods MERTK phosphorylation and downstream signaling were assessed by immunoblotting. Light transmission aggregometry, flow cytometry and microfluidic analysis were used to evaluate the impact of MERTK inhibition on platelet activation and stability of aggregates in vitro. The effects of MERTK inhibition on arterial and venous thrombosis, platelet accumulation at microvascular injury sites and tail bleeding times were determined with murine models. The effects of combined treatment with ADP-P2Y1&12 pathway antagonists and UNC2025 were also evaluated. Results and Conclusions Treatment with UNC2025 inhibited MERTK phosphorylation and downstream activation of AKT and SRC, decreased platelet activation, and protected animals from pulmonary embolism and arterial thrombosis without increasing bleeding times. The antiplatelet effect of UNC2025 was enhanced in combination with ADP-P2Y1&12 pathway antagonists, and a greater than additive effect was observed when these two agents with different mechanisms of inhibition were coadministered. TAM kinase signaling represents a potential therapeutic target, as inhibition of this axis, especially in combination with ADP-P2Y pathway antagonism, mediates decreased platelet activation, aggregate stability, and thrombus formation, with less hemorrhagic potential than current treatment strategies. The data presented here also demonstrate antithrombotic activity mediated by UNC2025, a novel translational agent, and support the development of TAM kinase inhibitors for clinical applications.
Collapse
Affiliation(s)
- B R Branchford
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
- University of Colorado Hemophilia and Thrombosis Center, Aurora, CO, USA
| | - T J Stalker
- Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - L Law
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
| | - G Acevedo
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
| | - S Sather
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
| | - C Brzezinski
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
| | - K M Wilson
- Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - K Minson
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Atlanta, GA, USA
- Department of Pediatrics, Section of Hematology/Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - A B Lee-Sherick
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
| | - P Davizon-Castillo
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
| | - C Ng
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
- University of Colorado Hemophilia and Thrombosis Center, Aurora, CO, USA
| | - W Zhang
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
| | - K B Neeves
- Department of Chemical & Biological Engineering, Colorado School of Mines, Golden, CO, USA
| | - S R Lentz
- Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - X Wang
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
| | - S V Frye
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - H Shelton Earp
- Lineberger Comprehensive Cancer Center, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - D DeRyckere
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Atlanta, GA, USA
- Department of Pediatrics, Section of Hematology/Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - L F Brass
- Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - D K Graham
- Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Atlanta, GA, USA
- Department of Pediatrics, Section of Hematology/Oncology, Emory University School of Medicine, Atlanta, GA, USA
| | - J A Di Paola
- Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA
- University of Colorado Hemophilia and Thrombosis Center, Aurora, CO, USA
- Graduate Program - Human Medical Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| |
Collapse
|
4
|
Lee-Sherick AB, Eisenman KM, Sather S, McGranahan A, Armistead PM, McGary CS, Hunsucker SA, Schlegel J, Martinson H, Cannon C, Keating AK, Earp HS, Liang X, DeRyckere D, Graham DK. Aberrant Mer receptor tyrosine kinase expression contributes to leukemogenesis in acute myeloid leukemia. Oncogene 2013; 32:5359-68. [PMID: 23474756 PMCID: PMC3898106 DOI: 10.1038/onc.2013.40] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/14/2012] [Accepted: 12/30/2012] [Indexed: 01/13/2023]
Abstract
Acute myeloid leukemia (AML) continues to be extremely difficult to treat successfully, and the unacceptably low overall survival rates mandate that we assess new potential therapies to ameliorate poor clinical response to conventional therapy. Abnormal tyrosine kinase activation in AML has been associated with poor prognosis and provides strategic targets for novel therapy development. We found that Mer receptor tyrosine kinase was over-expressed in a majority of pediatric (29/36, 80%) and adult (10/10, 100%) primary AML patient blasts at the time of diagnosis, and 100% of patient samples at the time of relapse. Mer was also found to be expressed in 12 of 14 AML cell lines (86%). In contrast, normal bone marrow myeloid precursors expressed little to no Mer. Following AML cell line stimulation with Gas6, a Mer ligand, we observed activation of prosurvival and proliferative signaling pathways, including phosphorylation of ERK1/2, p38, MSK1, CREB, ATF1, AKT and STAT6. To assess the phenotypic role of Mer in AML, two independent short-hairpin RNA (shRNA) constructs were used to decrease Mer expression in the AML cell lines Nomo-1 and Kasumi-1. Reduction of Mer protein levels significantly increased rates of myeloblast apoptosis two to threefold in response to serum starvation. Furthermore, myeloblasts with knocked-down Mer demonstrated decreased colony formation by 67-87%, relative to control cell lines (P<0.01). NOD-SCID-gamma mice transplanted with Nomo-1 myeloblasts with reduced levels of Mer had a significant prolongation in survival compared with mice transplanted with the parental or control cell lines (median survival 17 days in parental and control cell lines, versus 32-36 days in Mer knockdown cell lines, P<0.0001). These data suggest a role for Mer in acute myeloid leukemogenesis and indicate that targeted inhibition of Mer may be an effective therapeutic strategy in pediatric and adult AML.
Collapse
Affiliation(s)
- A B Lee-Sherick
- Department of Pediatrics, Division of Hematology, Oncology, and Bone Marrow Transplantation, Aurora, CO, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Abstract
The fission yeast cdc18(+) gene is required for both initiation of DNA replication and the mitotic checkpoint that normally inhibits mitosis in the absence of DNA replication. The cdc18(+) gene product contains conserved Walker A and B box motifs. Studies of other ATPases have shown that these motifs are required for nucleotide binding and hydrolysis, respectively. We have observed that mutant strains in which either of these motifs is disrupted are inviable. The effects of these mutations were examined by determining the phenotypes of mutant strains following depletion of complementing wild-type Cdc18. In both synchronous and asynchronous cultures, the nucleotide-hydrolysis motif mutant (DE286AA) arrests with a 1C-2C DNA content, and thus exhibits no obvious defects in entry into S phase or in the mitotic checkpoint. In contrast, in cultures synchronized by hydroxyurea arrest and release, the nucleotide-binding motif mutant (K205A) exhibits the null phenotype, with 1C and <1C DNA content, indicating a block in entry into S phase and loss of checkpoint control. In asynchronous cultures this mutant exhibits a mixed phenotype: a percentage of the population displays the null phenotype, while the remaining fraction arrests with a 2C DNA content. Thus, the phenotype exhibited by the K205A mutant is dependent on the cell-cycle position at which wild-type Cdc18 is depleted. These data indicate that both nucleotide binding and hydrolysis are required for Cdc18 function. In addition, the difference in the phenotypes exhibited by the nucleotide-binding and hydrolysis motif mutants is consistent with a two-step model for Cdc18 function in which nucleotide binding and hydrolysis are required for distinct aspects of Cdc18 function that may be executed at different points in the cell cycle.
Collapse
Affiliation(s)
- D DeRyckere
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA
| | | | | |
Collapse
|
8
|
Zhang QY, DeRyckere D, Lauer P, Koomey M. Gene conversion in Neisseria gonorrhoeae: evidence for its role in pilus antigenic variation. Proc Natl Acad Sci U S A 1992; 89:5366-70. [PMID: 1351681 PMCID: PMC49292 DOI: 10.1073/pnas.89.12.5366] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Antigenic variation of gonococcal pili results from the unidirectional transfer of genetic information from variant-encoding partial pilin genes to an active expression locus. Two potential mechanisms that may result in the observed alterations of gene linkage and organization are conversion and transformation. To determine the relative contributions of these two distinct pathways of recombination to pilus variation, gonococcal strains carrying defined frameshift, missense, and nonsense mutations within the pilin expression locus were constructed. Reversion to a piliated state required correction of the lesions and provided a simple means of scoring productive recombination and antigenic variation. Examination of the mutants revealed a lack of correspondence between the frequencies with which they could be transformed (10(-6) per recipient) and the incidence with which they gave rise to revertants (greater than 10(-4) per colony-forming unit per generation). Further, the rates of reversion demonstrated by these mutants were not altered by growth in the presence of DNase I, conditions that abolished intercellular transfer of chromosomal markers during cultivation. Through the use of a pilin mutant in which a frameshift mutation encompassed the introduction of a restriction endonuclease site, the symmetry of recombination that resulted in reversion could be scored by Southern hybridization. In all cases examined, the DNA alterations responsible for pilin variation were nonreciprocal events. The results favor the model that productive pilin gene rearrangements in gonococci arise by gene conversion.
Collapse
Affiliation(s)
- Q Y Zhang
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109-0402
| | | | | | | |
Collapse
|