Proline-Rich Tyrosine Kinase-2 (PYK2): A New Target for the Treatment of Hematopoietic Neoplasms with TEL-FGFR3 Fusion or FGFR3 Active Mutation.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3360-3360
Author(s):  
Daisuke Okamura ◽  
Fumiharu Yagasaki ◽  
Tomoya Maeda ◽  
Maho Ishikawa ◽  
Itsuro Jinnai ◽  
...  
Keyword(s):  
Cell Growth ◽  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Kinase Inhibitor ◽  
Myeloma Cell ◽  
Kinase Assay ◽  
G1 Arrest ◽  
Dependent Manner ◽  
Tyrosine Kinase 2

Abstract Constitutive activation of Fibroblast Growth Factor 3 (FGFR3) tyrosine kinase have been identified in various human cancers and have been reported to play an important role in some hematopoietic neoplasms. We have previously reported that TEL-FGFR3 in a patient with peripheral T-cell Lymphoma and AML conferred IL-3 independency to Ba/F3 cells and activates PLCγ, PK3K, STAT3, STAT5, MAPK through its constitutive tyrosine kinase activity in TEL-FGFR3 transfected Ba/F3 cells (TF-V5). In KMS-11, human multiple myeloma cell line which expresses constitutively active mutant FGFR3, activations of PI3K and STAT3 pathways have been reported. However, little is known about how FGFR3 tyrosine kinase (TK) activates these downstream molecules. Here, we show that PYK2, a member of focal adhesion kinases, plays a pivotal role for the activation of PI3K, STAT3 and STAT5 in FGFR3 oncogenic pathways, and is a candidate for therapeutic target. PP1/PP2, a kinase inhibitor of SRC and PYK2, inhibited the cell growth of TF-V5 and KMS-11 cells in a dose-dependent manner (IC50=15μM, 25μM respectively), not affecting the cell growth of IL-3 dependent Ba/F3 cells. Another specific SRC inhibitor did not affect the cell growth of TF-V5 and KMS-11 cells. TEL-FGFR3 transfection to Ba/F3 cells led to the overexpression of PYK2 but not FAK. Expression and phosphorylation of PYK2 were identified in KMS-11 cells. Immunoprecipitation analysis using FGFR3 TK inhibitor SU5402 showed that the activation of PYK2 which was recruited to FGFR3 was dependent on the kinase activity of FGFR3. The cell growth of TF-V5 was completely inhibited at the concentration of PP1/PP2(30μM), which inhibited auto-phosphorylation of PYK2. PP1/PP2 suppressed the activation of PI3K-ATK pathway and decreased expression of C-MYC, inducing G1-arrest of TF-V5. PP1/PP2 induced intrinsic apoptosis of TF-V5 and did not affect activation of BAX but decrease expression of BCL-2 and BCL-XL through inactivation of STAT3 and STAT5. PP1/PP2 also inhibited the activation of PI3K and STAT3 in KMS-11 cells, inducing G1-arrest and apoptosis. PP1/PP2 inhibited tyrosine kinase of PYK2 mesured by in vitro kinase assay (IC50=23μM, 13μM, respectively). Further PYK2 C-terminus Associated Protein (PAP) siRNA expression plasmid significantly decreased the proliferation of TF-V5 but not mock transfected Ba/F3 cells. Our data demonstrates that PYK2 is an attractive molecular target for FGFR3 associated hematopoietic neoplasm.

Combination of PP1/PP2 and LY294002 Induce Apoptosis Efficiently to TEL-FGFR3 Transfected Ba/F3 Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4465-4465
Author(s):  
Daisuke Okamura ◽  
Fumiharu Yagasaki ◽  
Tomoya Maeda ◽  
Maho Ishikawa ◽  
Itsurou Jinnai ◽  
...  
Keyword(s):  
Cell Growth ◽  
Tyrosine Kinase ◽  
Src Kinase ◽  
Specific Inhibitor ◽  
Cyclin D3 ◽  
G1 Phase ◽  
G1 Arrest ◽  
Dependent Manner ◽  
Tyrosine Kinase 2 ◽  
Dose Dependent

Abstract We previously reported that TEL-FGFR3 in a patient with peripheral T-cell lymphoma and AML conferred IL-3 independency to Ba/F3 cells and activates MAPKs, p38, PI3K, Stat3 and Stat5 through its constitutive tyrosine kinase (TK) activity in TEL-FGFR3 transfected Ba/F3 cells (TF-V5). Both FGFR3 TK specific inhibitor SU5402 and PI3K inhibitor LY294002 inhibited cell growth of TF-V5 in a dose dependent manner (IC50=5μM, 10μM respectively). SU5402(25μM) resulted in G1 arrest (90%) and induced 80% of apoptosis to TF-V5 after 24hr. LY294002(50μM) decreased expression of c-Myc, Cyclin D3 and CDK4 in TF-V5 and induced G1 arrest (90%) and apoptosis about 20% to TF-V5 after 24hr. SU5402 completely suppressed expression of Bcl-xL and Bcl-2 after 24hr. LY294002 partially suppressed these expressions. As LY294002 did not affect the phosphorylation of STAT5 and STAT3, we hypothesized that these distinct apoptosis inducing abilities between SU5402 and LY294002 might be caused by the difference of Bcl-xL and Bcl-2 expression levels. Recent report suggests that FGFR3 activates Stat5 through recruitment of Pyk2 (proline-rich tyrosine kinase 2)-Src to its juxta-membrane (JM) domain. Therefore, we examined whether PP1/PP2 which are known as Src kinase inhibitors inhibit TF-V5 cell growth. PP1 and PP2 inhibited TEL-FGFR3 induced cell proliferation in a dose dependent manner (IC50=15μM, 15μM respectively). In contrast, growth of mock with IL-3 was not inhibited at a high concentration of PP1or PP2(30μM). PP1/PP2 did not affect auto-phosphorylation of TEL-FGFR3. Interestingly, PP1/PP2 inhibit Tyr phosphorylation of Pyk2 except Tyr402 and markedly suppressed activation of Stat3, Stat5 without affecting MAPKs and PLC gamma activation. PP1/PP2 suppressed expression of Bcl-xL and Bcl-2 partially but not of Bax and induced apoptosis 20% and 30% respectively. PP1/PP2 partially blocks cell cycle at G1 phase. When TF-V5 was co-treated with PP1(30μM)+LY294002(50μM) or PP2(30μM)+LY294002(50μM), apoptosis was induced in 60–70% of TF-V5 cells which remained at G1 phase after 24hr. Although PP1+LY294002 or PP2+LY294002 did not suppress Bcl-xL and Bcl-2 completely like SU5402, PP1/PP2 induced N-terminal cleavage form of Bax. Conclusion: PP1/PP2 induces apoptosis in TF-V5 by activating Bax and by Pyk2-Src kinase inactivation that leads to the change of Bax/Bcl-2 or Bax/Bcl-XL ratio. Combination of PP1/PP2 and LY294002 induce high rate of apoptosis under G1 arrest in TF-V5 and may represent a novel approach against TEL-FGFR3 associated hematopoietic malignancies.

scholarly journals An Orally Administered Multitarget Tyrosine Kinase Inhibitor, SU11248, Is a Novel Potent Inhibitor of Thyroid Oncogenic RET/Papillary Thyroid Cancer Kinases

2006 ◽  
Vol 91 (10) ◽  
pp. 4070-4076 ◽  
Author(s):  
Dong Wook Kim ◽  
Young Suk Jo ◽  
Hye Sook Jung ◽  
Hyo Kyun Chung ◽  
Jung Hun Song ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Papillary Thyroid Cancer ◽  
Kinase Inhibitor ◽  
Kinase Assay ◽  
Dependent Manner ◽  
Papillary Thyroid ◽  
Inhibitory Effects

Abstract Context: The oncogenic RET/PTC tyrosine kinase causes papillary thyroid cancer (PTC). The use of inhibitors specific for RET/PTC may be useful for targeted therapy of PTC. Objective: The objective of the study was to evaluate the efficacies of the recently developed kinase inhibitors SU11248, SU5416, and SU6668 in inhibition of RET/PTC. Design: SU11248, SU5416, and SU6668 were synthesized, and their inhibitory potencies were evaluated using an in vitro RET/PTC kinase assay. The inhibitory effects of the compounds on RET/PTC were evaluated by quantifying the autophosphorylation of RET/PTC, signal transducer and activator of transcription (STAT)-3 activation, and the morphological reversal of RET/PTC-transformed cells. Results: An in vitro kinase assay revealed that SU5416, SU6668, and SU11248 inhibited phosphorylation of the synthetic tyrosine kinase substrate peptide E4Y by RET/PTC3 in a dose-dependent manner with IC50 of approximately 944 nm for SU5416, 562 nm for SU6668, and 224 nm for SU11248. Thus, SU11248 effectively inhibits the kinase activity of RET/PTC3. RET/PTC-mediated Y705 phosphorylation of STAT3 was inhibited by addition of SU11248, and the inhibitory effects of SU11248 on the tyrosine phosphorylation and transcriptional activation of STAT3 were very closely correlated with decreased autophosphorylation of RET/PTC. SU11248 caused a complete morphological reversion of transformed NIH-RET/PTC3 cells and inhibited the growth of TPC-1 cells that have an endogenous RET/PTC1. Conclusion: SU11248 is a highly effective tyrosine kinase inhibitor of the RET/PTC oncogenic kinase.

scholarly journals Identification of Vinyl Sulfone Derivatives as EGFR Tyrosine Kinase Inhibitor: In Vitro and In Silico Studies

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2211
Author(s):  
Thitinan Aiebchun ◽  
Panupong Mahalapbutr ◽  
Atima Auepattanapong ◽  
Onnicha Khaikate ◽  
Supaphorn Seetaha ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Inhibitory Activity ◽  
In Silico ◽  
Kinase Inhibitor ◽  
Kinase Assay ◽  
Vinyl Sulfone ◽  
Egfr Tyrosine Kinase ◽  
In Silico Studies ◽  
Sulfone Derivatives

Epidermal growth factor receptor (EGFR), overexpressed in many types of cancer, has been proved as a high potential target for targeted cancer therapy due to its role in regulating proliferation and survival of cancer cells. In the present study, a series of designed vinyl sulfone derivatives was screened against EGFR tyrosine kinase (EGFR-TK) using in silico and in vitro studies. The molecular docking results suggested that, among 78 vinyl sulfones, there were eight compounds that could interact well with the EGFR-TK at the ATP-binding site. Afterwards, these screened compounds were tested for the inhibitory activity towards EGFR-TK using ADP-Glo™ kinase assay, and we found that only VF16 compound exhibited promising inhibitory activity against EGFR-TK with the IC50 value of 7.85 ± 0.88 nM. In addition, VF16 showed a high cytotoxicity with IC50 values of 33.52 ± 2.57, 54.63 ± 0.09, and 30.38 ± 1.37 µM against the A431, A549, and H1975 cancer cell lines, respectively. From 500-ns MD simulation, the structural stability of VF16 in complex with EGFR-TK was quite stable, suggesting that this compound could be a novel small molecule inhibitor targeting EGFR-TK.

scholarly journals Fgr but not Syk tyrosine kinase is a target for beta2 integrin-induced c-Cbl-mediated ubiquitination in adherent human neutrophils

2003 ◽  
Vol 370 (2) ◽  
pp. 687-694 ◽  
Author(s):  
Fredrik MELANDER ◽  
Tommy ANDERSSON ◽  
Karim DIB
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Activity ◽  
Src Kinase ◽  
E3 Ligase ◽  
In Vitro Assay ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
Vitro Assay ◽  
Β2 Integrin

An early and critical event in β2 integrin signalling during neutrophil adhesion is activation of Src tyrosine kinases and Syk. In the present study, we report Src kinase-dependent β2 integrin-induced tyrosine phosphorylation of Cbl occurring in parallel with increased Cbl-associated tyrosine kinase activity. These events concurred with activation of Fgr and, surprisingly, also with dissociation of this Src tyrosine kinase from Cbl. Moreover, the presence of the Src kinase inhibitor PP1 in an in vitro assay had only a limited effect on the Cbl-associated kinase activity. These results suggest that an additional active Src-dependent tyrosine kinase associates with Cbl. The following observations imply that Syk is such a kinase: (i) β2 integrins activated Syk in a Src-dependent manner, (ii) Syk was associated with Cbl much longer than Fgr was, and (iii) the Syk inhibitor piceatannol (3,4,3′,5′-tetrahydroxy-trans-stilbene) abolished the Cbl-associated kinase activity in an in vitro assay. Effects of the mentioned interactions between these two kinases and Cbl may be related to the finding that Cbl is a ubiquitin E3 ligase. Indeed, we detected β2 integrin-induced ubiquitination of Fgr that, similar to the phosphorylation of Cbl, was abolished in cells pretreated with PP1. However, the ubiquitination of Fgr did not cause any apparent degradation of the protein. In contrast with Fgr, Syk was not modified by the E3 ligase. Thus Cbl appears to be essential in β2 integrin signalling, first by serving as a matrix for a subsequent agonist-induced signalling interaction between Fgr and Syk, and then by mediating ubiquitination of Fgr which possibly affects its interaction with Cbl.

Raf Inhibitor BAY 43-9006 Induces Bim Dephosphorylation and Activates the Intracellular Apoptotic Pathway in AML.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3367-3367 ◽  
Author(s):  
Weiguo Zhang ◽  
Marina Konopleva ◽  
Teresa McQueen ◽  
Jorje Cortes ◽  
James McCubrey ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Leukemia Cell ◽  
Mapk Signaling ◽  
Kinase Assay ◽  
Dependent Manner ◽  
Apoptotic Pathway ◽  
Apoptosis Protein ◽  
Dose Dependent

Abstract We have previously demonstrated constitutive activation of MAPK signaling in 70% of primary AML samples (Millela et al, JCI108:851–859, 2001), suggesting that upstream kinases (Raf and MEK) may play a role in the leukemic transformation of myeloid cells. BAY 43-9006 is a small molecule Raf kinase inhibitor that has demonstrated potent anti-tumor activity against solid human tumors in xenograft models. In this study, we tested the hypothesis that BAY 43-9006 inhibits leukemia cell growth and/or induces apoptosis by suppressing the activity of the MAPK pathway. In the in vitro kinase assay, BAY 43-9006 inhibited both Raf-1 and B-Raf-mediated MEK1 phosphorylation in a dose-dependent manner, with Raf-1 kinase being more sensitive to the inhibitory effects of BAY 43-9006 (IC50Raf-1, 1.37 μM vs. IC50B-Raf, 4.64 μM). BAY 43-9006 suppressed MEK1/2 and ERK phosphorylation in the AML cell lines OCI-AML3, HL-60, U937 and KG-1 in a dose-dependent manner after 24 hr treatment. Unexpectedly, BAY 43-9006 also inhibited AKT phosphorylation on Ser473 (after 4.5 hrs). BAY 43-9006 inhibited growth of AML cells in a dose- and time-dependent manner. The 50% inhibitory concentration (IC50) of BAY 43-9006 was 0.39, 1.14, 2.86 and 2.80 μM, respectively in OCI-AML3, HL-60, U937 and KG-1 cells after 72 hrs. This growth-inhibitory effect was mediated by a dose-dependent induction of cell cycle arrest in G1 mediated by the down-regulation of the cell cycle-related proteins cyclin E, cdk2 and cdc2, followed by induction of apoptosis after 72 hrs. In primary AML patient samples, BAY 43-9006 not only inhibited cell growth and induced apoptosis after 48–72 hrs in vitro, but also preferentially inhibited colony formation of AML progenitor cells compared to normal bone marrow cells [IC50: 2.33 μM vs. 9.34μM (CFU-GM), 5.69 μM (Erythroid) and 3.75 μM (Mixed), respectively]. Time-course analyses demonstrated that BAY 43-9006 suppressed phosphorylation of the pro-apoptotic protein Bim (at 4.5 hrs), caused loss of the mitochondrial membrane potential and cytochrome c release (at 6 hrs) followed by cleavage of caspases-3 and -9 but not of caspase-8, suggesting primary involvement of the intrinsic mitochondrial pathway. Furthermore, the pro-apoptotic proteins Bim and Bax were up-regulated after 48 hrs of BAY 43-9006 treatment, and the level of the inhibitor-of-apoptosis protein Survivin was down-regulated after 48 hrs. In summary, our data demonstrates that BAY 43-9006 inhibits Raf-MEK-ERK signaling and induces apoptosis in AML via Bim de-phosphorylation and activation of the intrinsic apoptotic pathway. The potential of BAY 43-9006 in the therapy of AML patients will be tested in a Phase I clinical trial.

The Novel, Orally Available Multi-Kinase Inhibitor BAY 73-4506 Targets Myeloma Cells and Their Bone Marrow Microenvironment.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2525-2525
Author(s):  
Marc S. Raab ◽  
Iris Breitkreutz ◽  
Podar Klaus ◽  
Jing Zhang ◽  
Simona Blotta ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Endothelial Cell ◽  
Cell Growth ◽  
Cell Lines ◽  
Kinase Inhibitor ◽  
Dependent Manner ◽  
The Novel ◽  
Phase I Clinical Trials ◽  
Potent Inducer

Abstract Multitargeted treatment approaches have been shown to be more effective than single agent therapy in multiple myeloma (MM). In addition, agents targeting not only the MM cells directly but also their microenvironment, like bone marrow stromal cells (BMSCs), endothelial cells, and osteoclasts (OCLs) causing enhancement of tumor cell growth, angiogenesis, and MM bone disease, respectively, are promising new treatment modalities for this still non-curable disease.Here we investigated the novel, orally available multi-kinase inhibitor BAY 73-4506, currently in phase I clinical trials, for its therapeutic effect in MM. BAY is a potent inhibitor of angiogenic (VEGFR 1-3, PDGFR-b), as well as oncogenic, kinases (cKIT, RET, FGFR, Raf). We first tested the ability of BAY to suppress MM cell proliferation and survival in a wide array of MM cell lines (MM.1S, RPMI 8226, NCI H929, OPM2, KMS11, KMS 18, INA6, U266, KMS12BM, S6B45), including those resistant to conventional chemotherapeutics (MM.1R, Dox40, LR5). Our data show that BAY is active in all cell lines tested in a low micromolar range equivalent to concentrations achieved in patient plasma during the first clinical trial in solid tumors. Importantly, BAY also overcomes the growth advantage conferred in a BMSC-MM, as well as an endothelial cell-MM, coculture system. BAY treatment abrogates MEK, ERK and AKT phosphorylation in a time and dose dependent manner, followed by induction of apoptosis, evidenced by Annexin staining and DNA fragmentation. Since VEGF signaling pathway is a potent inducer of angiogenesis and BAY targets VEGFR 1-3, we examined anti-angiogenic properties of BAY. This compound inhibits endothelial cell growth and endothelial cell tubuli formation in vitro at concentrations less than 1mM; moreover, BAY markedly inhibits the VEGF-induced cell migration on fibronectin. Activation of MAP kinase is a critical event during OCL differentiation, activation, and survival; BAY inhibits osteoclastogenesis, evidenced by blockade of M-CSF/RANKL-triggered differentiation of mononuclear cells to TRAP-positive osteoclasts, an important marker of osteoclastogenesis. Finally, combination treatment of BAY with dexamethasone shows synergistic effects on MM cell growth and survival. These in vitro experiments on the effects of BAY on MM tumor cells directly, in co-culture with endothelial or BMSCs, as well as on osteoclast differentiation, provides the basis for its evaluation in a murine model of human MM to confirm these promising in vitro effects of this novel multi-kinase inhibitor, finally leading to clinical evaluation to improve patient outcome.

Vasopressin-mediated mitogenic signaling in intestinal epithelial cells

2002 ◽  
Vol 282 (3) ◽  
pp. C434-C450 ◽  
Author(s):  
Terence Chiu ◽  
Steven S. Wu ◽  
Chintda Santiskulvong ◽  
Pisit Tangkijvanich ◽  
Hal F. Yee ◽  
...  
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Intestinal Epithelial ◽  
Src Family Kinase ◽  
Egfr Tyrosine Kinase ◽  
Tyrosine Kinase 2

The role of G protein-coupled receptors and their ligands in intestinal epithelial cell signaling and proliferation is poorly understood. Here, we demonstrate that arginine vasopressin (AVP) induces multiple intracellular signal transduction pathways in rat intestinal epithelial IEC-18 cells via a V1A receptor. Addition of AVP to these cells induces a rapid and transient increase in cytosolic Ca2+concentration and promotes protein kinase D (PKD) activation through a protein kinase C (PKC)-dependent pathway, as revealed by in vitro kinase assays and immunoblotting with an antibody that recognizes autophosphorylated PKD at Ser916. AVP also stimulates the tyrosine phosphorylation of the nonreceptor tyrosine kinase proline-rich tyrosine kinase 2 (Pyk2) and promotes Src family kinase phosphorylation at Tyr418, indicative of Src activation. AVP induces extracellular signal-related kinase (ERK)-1 (p44mapk) and ERK-2 (p42mapk) activation, a response prevented by treatment with mitogen-activated protein kinase kinase (MEK) inhibitors (PD-98059 and U-0126), specific PKC inhibitors (GF-I and Ro-31-8220), depletion of Ca2+ (EGTA and thapsigargin), selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (tyrphostin AG-1478, compound 56), or the selective Src family kinase inhibitor PP-2. Furthermore, AVP acts as a potent growth factor for IEC-18 cells, inducing DNA synthesis and cell proliferation through ERK-, Ca2+-, PKC-, EGFR tyrosine kinase-, and Src-dependent pathways.

Vemurafenib Inhibits Myeloma Cell Growth Independent Of BRAF V600E Mutations, Potentiates The Activity Of Established Anti-Myeloma Drugs, but impairs Osteogenesis Via An HGF Autocrine Loop In Bone Marrow Stromal Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5363-5363 ◽  
Author(s):  
Arnold Bolomsky ◽  
Heinz Ludwig ◽  
Niklas Zojer
Keyword(s):  
Cell Growth ◽  
Cell Lines ◽  
Stromal Cells ◽  
Inhibitory Action ◽  
Dna Analysis ◽  
Myeloma Cell ◽  
Braf V600e Mutation ◽  
Braf V600e ◽  
Dependent Manner

Abstract Introduction Vemurafenib is a small molecule inhibitor designed for the treatment of BRAF V600E mutated malignancies such as melanoma, where it shows remarkable anti-tumor activity. However, prolonged exposure usually is associated with emerging resistance, likely a consequence of upregulation of growth factor signaling. In multiple myeloma, BRAF V600E mutations have been noted in a small subset of patients providing a rationale for the use of vemurafenib in these patients. In the current study we aimed to investigate the activity of vemurafenib in MM in vitro in relation to presence or absence of a BRAF V600E mutation, alone or in combination with other MM drugs and the role of major myeloma growth factors in modulating its activity. Furthermore the impact of vemurafenib on bone formation was investigated. Methods BRAF V600E mutation status was analyzed by immunohistochemistry and DNA analysis in 7 human myeloma cell lines (MMCLs) (OPM-2, KMS-12-BM, RPMI8226, SK-MM-1, U266, NCI-H929, MM.1S). Viability was assessed after a 96h treatment period in the presence or absence of vemurafenib ± lenalidomide, pomalidomide, bortezomib and carfilzomib. Apoptosis was determined by Annexin V and 7-AAD staining. For rescue experiments vemurafenib was combined with recombinant human IL-6, HGF, IGF-1 or insulin. Human immortalized mesenchymal stromal cells (MSC TERT+) were cultured in osteogenic medium in the presence of vemurafenib and/or a specific c-met inhibitor (PHA-665752) and analyzed at day 7, 14 and 21 of differentiation by qPCR, ALP activity assessment and/or alizarin red S staining. Results We observed a BRAF V600E mutation verified by immunohistochemistry and DNA analysis in 1 (U266) of 7 MM cell lines tested. Treatment with vemurafenib (0-10 µM) suppressed viability in all MMCLs tested in a dose dependent manner, independent of mutation status. Induction of apoptosis was observed in 4 of 4 MMCLs (range: 14.89-37.69%; P < 0.05). Combination of vemurafenib with immunomodulatory drugs (lenalidomide, pomalidomide) and proteasome inhibitors (bortezomib, carfilzomib) led to a synergistic or additive impairment of MM cell growth. In contrast, concurrent treatment with myeloma growth factors resulted in a partial rescue from the inhibitory action of vemurafenib. We observed a significant rescue effect (range: 5.3-21.3%; P<0.05) in 1 of 7 MMCLs by IL-6, 2 of 7 by insulin and 5 of 7 by IGF-1. In BM stromal cells, we detected upregulation of HGF (2.15 fold induction; P<0.05) and RANKL (4.38 fold induction, P<0.05) under vemurafenib treatment. Moreover, vemurafenib impaired osteogenesis indicated by a significant downregulation of osteogenic transcription factors Runx2 and Dlx-5, alkaline phosphatase activity and matrix mineralization in a dose dependent manner. Of note, the inhibitory action of vemurafenib on osteogenesis was overcome by concurrently c-met inhibition (ALP activity relative to control: 0.70 ± 0.09 vs. 0.91 ± 0.1; P<0.05 and 0.48 ± 0.13 vs. 0.71 ± 0.05; P<0.05 using vemurafenib at 10 nM and 5 µM in the presence or absence of a specific c-met inhibitor, respectively) suggesting that HGF signalling is responsible, at least in part, for the inhibitory action on osteoblast development. Conclusion Our results indicate anti-myeloma activity of vemurafenib independent of the presence of a BRAFV600E mutation in vitro. We observed an inhibitory activity against MM cell growth and induction of apoptosis in all MM cell lines tested. Furthermore, vemurafenib showed synergistic or additive effects in combination with novel agents. The inhibitory effects of vemurafenib were partially counteracted by cytokines such as IGF-1. Targeting of MM growth factor signalling pathways might therefore further improve response rates and avoid unwanted off-target effects such as impairment of osteoblast development. Disclosures: No relevant conflicts of interest to declare.

scholarly journals CGP 57148, a Tyrosine Kinase Inhibitor, Inhibits the Growth of Cells Expressing BCR-ABL, TEL-ABL, and TEL-PDGFR Fusion Proteins

Blood ◽  
1997 ◽  
Vol 90 (12) ◽  
pp. 4947-4952 ◽  
Author(s):  
Martin Carroll ◽  
Sayuri Ohno-Jones ◽  
Shu Tamura ◽  
Elisabeth Buchdunger ◽  
Jürg Zimmermann ◽  
...  
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Kinase Inhibitor ◽  
Philadelphia Chromosome ◽  
Lymphocytic Leukemia ◽  
Protein Tyrosine Kinases ◽  
Protein Tyrosine

Abstract CGP 57148 is a compound of the 2-phenylaminopyrimidine class that selectively inhibits the tyrosine kinase activity of the ABL and the platelet-derived growth factor receptor (PDGFR) protein tyrosine kinases. We previously showed that CGP 57148 selectively kills p210BCR-ABL–expressing cells. To extend these observations, we evaluated the ability of CGP 57148 to inhibit other activated ABL tyrosine kinases, including p185BCR-ABL and TEL-ABL. In cell-based assays of ABL tyrosine phosphorylation, inhibition of ABL kinase activity was observed at concentrations similar to that reported for p210BCR-ABL. Consistent with the in vitro profile of this compound, the growth of cells expressing activated ABL protein tyrosine kinases was inhibited in the absence of exogenous growth factor. Growth inhibition was also observed with a p185BCR-ABL–positive acute lymphocytic leukemia (ALL) cell line generated from a Philadelphia chromosome–positive ALL patient. As CGP 57148 inhibits the PDGFR kinase, we also showed that cells expressing an activated PDGFR tyrosine kinase, TEL-PDGFR, are sensitive to this compound. Thus, this compound may be useful for the treatment of a variety of BCR-ABL–positive leukemias and for treatment of the subset of chronic myelomonocytic leukemia patients with a TEL-PDGFR fusion protein.

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