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Oncogenic kinase signaling
Abstract and Figures
Protein-tyrosine kinases (PTKs) are important regulators of intracellular signal-transduction pathways mediating development and multicellular communication in metazoans. Their activity is normally tightly controlled and regulated. Perturbation of PTK signalling by mutations and other genetic alterations results in deregulated kinase activity and malignant transformation. The lipid kinase phosphoinositide 3-OH kinase (PI(3)K) and some of its downstream targets, such as the protein-serine/threonine kinases Akt and p70 S6 kinase (p70S6K), are crucial effectors in oncogenic PTK signalling. This review emphasizes how oncogenic conversion of protein kinases results from perturbation of the normal autoinhibitory constraints on kinase activity and provides an update on our knowledge about the role of deregulated PI(3)K/Akt and mammalian target of rapamycin/p70S6K signalling in human malignancies.
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... It is associated with STK3 (MST2) and promotes its ubiquitin-mediated degradation, which induces the nuclear translocation of the TAZ oncogene and subsequent transcriptional activation of the TAZ/TEAD complex. TAZ/TEAD enhances the transcription of specific genes, such as CTGF, which promotes cell proliferation, epithelial-mesenchymal transition, invasion, and cellular transformation [79,80]. Conversely, depletion of PIN1 in melanoma cells leads to retention of TAZ in the cytoplasm, followed by a decrease in CTGF and the final inhibition of melanoma development. ...
Melanoma is the most aggressive form of skin cancer. In the advanced stage of development, it is resistant to currently available therapeutic modalities. Increased invasiveness and metastatic potential depend on several proteins involved in various signal transduction pathways. Hippo signaling plays a vital role in malignant transformation. Dysfunctions of the Hippo pathway initiate the expression of tumor growth factors and are associated with tumor growth and metastasis formation. This review summarizes the recent achievements in studying the role of the Hippo pathway in melanoma pathogenesis and points to the potential specific targets for anti-melanoma therapy.
... This process recruits adaptor proteins that harbour Src homology-2 (SH2) or phosphotyrosine (pY) binding domains towards the pY-containing region of RTKs. Since the SH2 domains play a central role in the recognition of the pY sites, disruption or over-activation of these adaptor proteins significantly impacts the generation of tumorigenesis [2,3]. Thus, considerable attention has been focused on investigating site-specific interactions between SH2 domains and RTKs. ...
The Drosophila downstream receptor kinase (Drk), a homologue of human GRB2, participates in the signal transduction from the extracellular to the intracellular environment. Drk receives signals through the interaction of its Src homology 2 (SH2) domain with the phosphorylated tyrosine residue in the receptor tyrosine kinases (RTKs). Here, we present the solution NMR structure of the SH2 domain of Drk (Drk-SH2), which was determined in the presence of a phosphotyrosine (pY)-containing peptide derived from a receptor tyrosine kinase, Sevenless (Sev). The solution structure of Drk-SH2 possess a common SH2 domain architecture, consisting of three β strands imposed between two α helices. Additionally, we interpret the site-specific interactions of the Drk-SH2 domain with the pY-containing peptide through NMR titration experiments. The dynamics of Drk-SH2 were also analysed through NMR-relaxation experiments as well as the molecular dynamic simulation. The docking simulations of the pY-containing peptide onto the protein surface of Drk-SH2 provided the orientation of the peptide, which showed a good agreement with the analysis of the SH2 domain of GRB2.
... However, no clear correlation between the potential intrinsic activation of these effectors and the clinical course of the disease has been demonstrated so far, perhaps because of signal pathway redundancies. Receptor tyrosine kinases (RTKs), such as insulin-like growth factor 1 receptor (IGF1R), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor 3 (FGFR3) and erb-b2 receptor tyrosine kinase 2 (ERBB2), which are intimately connected with growth, survival, differentiation and migration processes, may play an important role in this regard [17][18][19]. Genetic alterations of RTKs and of their effectors have been linked to tumor development in various cancers, and preclinical experiments as well as clinical studies have shown that patients with RTK mutations or aberrant RTK expression may benefit from treatment with RTK inhibitors [20][21][22][23][24][25]. ...
High expression of the receptor tyrosine kinase (RTK) insulin-like growth factor-1 receptor (IGF1R) and RTK mutations are associated with high-risk/worse prognosis in multiple myeloma (MM). Combining the pIGF1R/pINSR inhibitor linsitinib with the proteasome inhibitor (PI) bortezomib seemed promising in a clinical trial, but IGF1R expression was not associated with therapy response. Because the oncogenic impact of IGF1R mutations is so far unknown, we investigated the functional impact of IGF1R mutations on survival signaling, viability/proliferation and survival response to therapy. We transfected four human myeloma cell lines (HMCLs) with IGF1RWT, IGF1RD1146N and IGF1RN1129S (Sleeping Beauty), generated CRISPR-Cas9 IGF1R knockouts in the HMCLs U-266 (IGF1RWT) and L-363 (IGF1RD1146N) and tested the anti-MM activity of linsitinib alone and in combination with the second-generation PI carfilzomib in seven HMCLs. IGF1R knockout entailed reduced proliferation. Upon IGF1R overexpression, survival signaling was moderately increased in all HCMLs and slightly affected by IGF1RN1129S in one HMCL, whereby the viability remained unaffected. Expression of IGF1RD1146N reduced pIGF1R-Y1135, especially under serum reduction, but did not impact downstream signaling. Linsitinib and carfilzomib showed enhanced anti-myeloma activity in six out of seven HMCL irrespective of the IGF1R mutation status. In conclusion, IGF1R mutations can impact IGF1R activation and/or downstream signaling, and a combination of linsitinib with carfilzomib might be a suitable therapeutic approach for MM patients potentially responsive to IGF1R blockade.
... Dysregulation of RTK signaling impacts various diseases, especially cancer 4 , as they promote tumorigenesis 5 , migration 6 , as well as tumor angiogenesis 7 . Therefore, RTKs have emerged as therapeutic targets and clinical prognostic factors for cancer [8][9][10] . Among 20 RTK subfamilies, RTK class III (PDGFR family) which includes PDGFRα, PDGFRβ, C-KIT, CSF1R, and FLT3, is highly expressed in various types of epithelial cancers 9 and associated with poor prognosis 11,12 via promoting tumor angiogenesis and metastasis 1,6,12 . ...
Binding affinity is an important factor in drug design to improve drug-target selectivity and specificity. In this study, in silico techniques based on molecular docking followed by molecular dynamics (MD) simulations were utilized to identify the key residue(s) for CSF1R binding affinity among 14 pan-tyrosine kinase inhibitors and 15 CSF1R-specific inhibitors. We found tryptophan at position 550 (W550) on the CSF1R binding site interacted with the inhibitors' aromatic ring in a π–π way that made the ligands better at binding. Upon W550-Alanine substitution (W550A), the binding affinity of trans-(−)-kusunokinin and imatinib to CSF1R was significantly decreased. However, in terms of structural features, W550 did not significantly affect overall CSF1R structure, but provided destabilizing effect upon mutation. The W550A also did not either cause ligand to change its binding site or conformational changes due to ligand binding. As a result of our findings, the π–π interaction with W550's aromatic ring could be still the choice for increasing binding affinity to CSF1R. Nevertheless, our study showed that the increasing binding to W550 of the design ligand may not ensure CSF1R specificity and inhibition since W550-ligand bound state did not induce significantly conformational change into inactive state.
... There are 58 human receptor tyrosine kinases (RTKs) that can be categorized into 20 sub-families. 1 The identification of multiple modes of oncogenic alterations in many of these RTKs (single amino acid substitutions, insertions and deletions, gene amplification, protein over-expression, and chromosomal rearrangement) and the subsequent development of targeted therapies has transformed the treatment landscape of non-small cell lung cancer (NSCLC) over the past 20 years. Following the discovery of ALK and ROS1 fusions in NSCLC in 2007, 2,3 fusions in the rearranged during transfection (RET) proto-oncogene in NSCLC were reported in 2011 by four groups nearly simultaneously. ...
Selpercatinib, a potent and highly selective RET kinase inhibitor with significant CNS activity, has recently gained US approval for the treatment of NSCLC harboring RET fusions (RET+) based on a large-scale single-arm study. The LIBRETTO-431 trial was the global pivotal registration phase 3 trial comparing selpercatinib to platinum-based chemotherapy with or without pembrolizumab as the first-line treatment of patients with advanced RET+ NSCLC. Never-smokers constituted 67.4% of the RET+ NSCLC patients enrolled. KIF5B-RET made up the vast majority (77%) of the RET+ fusion variant with known fusion partner. The results of this study demonstrated significant improvement in progression-free survival (PFS) benefit as well as impressive intracranial disease response in participants treated with selpercatinib as compared to those treated with chemotherapy, with a HR [hazard ratio] of 0.46 (95% CI 0.33–0.70; P < 0.001) for the intention-to-treat (ITT)-pembrolizumab group and HR of 0.46 (95% CI 0.31–0.70, P < 0.001) for the overall ITT-group of patients. The addition of pembrolizumab to platinum/pemetrexed chemotherapy resulted in numerically identical PFS (11.2 months). These results point to selpercatinib’s superiority to traditional chemotherapy regimens in the treatment of NSCLC harboring RET fusions and add to literature on the salience of targeted precision oncology and lack of efficacy of immune checkpoint inhibitor in NSCLC patients with never-smoker predominant actionable driver mutations. RET+ NSCLC should be added to the list of molecular subtypes (EGFR+, ALK+, ROS1+) of NSCLC to be excluded in chemoimmunotherapy trial.
Conformational changes of catalytically-important structural elements are a key feature of the regulation mechanisms of protein kinases and are important for dictating inhibitor binding modes and affinities. The lack of widely applicable methods for tracking kinase conformational changes in solution has hindered our understanding of kinase regulation and our ability to design conformationally selective inhibitors. Here we provide an overview of two recently developed methods that detect conformational changes of the regulatory activation loop and αC-helix of kinases and that yield complementary information about allosteric mechanisms. An intramolecular Förster resonance energy transfer-based approach provides a scalable platform for detecting and classifying structural changes in high-throughput, as well as quantifying ligand binding cooperativity, shedding light on the energetics governing allostery. The pulsed electron paramagnetic resonance technique double electron-electron resonance provides lower throughput but higher resolution information on structural changes that allows for unambiguous assignment of conformational states and quantification of population shifts. Together, these methods are shedding new light on kinase regulation and drug interactions and providing new routes for the identification of novel kinase inhibitors and allosteric modulators.
Translocations in hematologic disease of myeloid or lymphoid origin with breakpoints at chromosome band 12p13 frequently result in rearrangements of the Ets variant gene 6 (ETV6). As a consequence either the ETS DNA-binding domain or the Helix-Loop-Helix (HLH) oligomerization domain of ETV6 is fused to different partner genes. We show here that a t(9; 12)(p24; p13) in a case of early pre-B acute lymphoid leukemia and a t(9; 15; 12)(p24; q15; p13) in atypical chronic myelogenous leukemia in transformation involve the ETV6 gene at 12p13 and the JAK2 gene at 9p24. In each case different fusion mRNAs were found, with only one resulting in an open reading frame for a chimeric protein consisting of the HLH oligomerization domain of ETV6 and the protein tyrosine kinase (PTK) domain of JAK2. The cloning of the complete human JAK2 coding and genomic sequences and of the genomic junction fragments of the translocations allowed a characterization of the different splice events leading to the various mRNAs. JAK2 plays a central role in non–protein tyrosine kinase receptor signaling pathways, which could explain its involvement in malignancies of different hematologic lineages. Besides hop in Drosophila no member of the JAK family has yet been implicated in tumorigenesis.
Deregulation of cell cycle checkpoints is an almost universal abnormality in human cancers and is most often due to loss-of-function
mutations of tumor suppressor genes such as Rb, p53, or p16INK4a. In this study, we demonstrate that BCR/ABL inhibits the expression of a key cell cycle inhibitor, p27Kip1, by signaling through a pathway involving phosphatidylinositol 3-kinase (PI3K). p27Kip1 is a widely expressed inhibitor of cdk2, an essential cell cycle kinase regulating entry into S phase. We demonstrate that
the decrease of p27Kip1 is directly due to BCR/ABL in hematopoietic cells by two different approaches. First, induction of BCR/ABL by a tetracycline-regulated
promoter is associated with a reversible down-regulation of p27Kip1. Second, inhibition of BCR/ABL kinase activity with the Abl tyrosine kinase inhibitor STI571 rapidly increases p27Kip1 levels. The PI3K inhibitor LY-294002 blocks the ability of BCR/ABL to induce p27Kip1down-regulation and inhibits BCR/ABL-induced entry into S phase. The serine/threonine kinase AKT/protein kinase B is a known
downstream target of PI3K. Transient expression of an activated mutant of AKT was found to decrease expression of p27Kip1, even when PI3K was inhibited by LY-294002. The mechanism of p27Kip1 regulation is primarily related to protein stability, since inhibition of proteasome activity increased p27Kip1 levels in BCR/ABL-transformed cells, whereas very little change in p27 transcription was found. Overall, these data are consistent
with a model in which BCR/ABL suppresses p27Kip1protein levels through PI3K/AKT, leading to accelerated entry into S phase. This activity is likely to explain in part previous
studies showing that activation of PI3K was required for optimum transformation of hematopoietic cells by BCR/ABL in vitro and in vivo.
In Philadelphia chromosome-positive human leukemias, the c-abl proto-oncogene on chromosome 9 becomes fused to the bcr gene on chromosome 22, and chimeric Bcr-Abl proteins are produced. The fused Bcr sequences activate the tyrosine kinase, actin-binding, and transforming functions of Abl. Activation of the Abl transforming function has been shown to require two distinct domains of Bcr: domain 1 (Bcr amino acids 1 to 63) and domain 2 (Bcr amino acids 176 to 242). The amino acid sequence of domain 1 indicates that it may be a coiled-coil oligomerization domain. We show here that domain 1 of Bcr forms a homotetramer. Tetramerization of Bcr-Abl through Bcr domain 1 correlates with activation of the tyrosine kinase and F-actin-binding functions of Abl. Disruption of the coiled coil by insertional mutagenesis inactivates the oligomerization function as well as the ability of Bcr-Abl to transform Rat-1 fibroblasts or to abrogate interleukin-3 dependence in lymphoid cells. These results strongly suggest that Bcr-Abl oligomers are the active entities in transformation.
STI 571 (formerly known as CGP 57148B) is a known inhibitor of the c-abl, bcr-abl, and platelet-derived growth-factor receptor (PDGFR) tyrosine kinases. This compound is being evaluated in clinical trials for the treatment of chronic myelogenous leukemia. We sought to extend the activity profile of STI 571 by testing its ability to inhibit the tyrosine kinase activity of c-kit, a receptor structurally similar to PDGFR. We treated a c-kit expressing a human myeloid leukemia cell line, M-07e, with STI 571 before stimulation with Steel factor (SLF). STI 571 inhibited c-kit autophosphorylation, activation of mitogen-activated protein (MAP) kinase, and activation of Akt without altering total protein levels of c-kit, MAP kinase, or Akt. The concentration that produced 50% inhibition for these effects was approximately 100 nmol/L. STI 571 also significantly decreased SLF-dependent growth of M-07e cells in a dose-dependent manner and blocked the antiapoptotic activity of SLF. In contrast, the compound had no effect on MAP kinase activation or cellular proliferation in response to granulocyte-macrophage colony-stimulating factor. We also tested the activity of STI 571 in a human mast cell leukemia cell line (HMC-1), which has an activated mutant form of c-kit. STI 571 had a more potent inhibitory effect on the kinase activity of this mutant receptor than it did on ligand-dependent activation of the wild-type receptor. These findings show that STI 571 selectively inhibits c-kit tyrosine kinase activity and downstream activation of target proteins involved in cellular proliferation and survival. This compound may be useful in treating cancers associated with increased c-kit kinase activity.
Each day, approximately 50 to 70 billion cells perish in the average adult because of programmed cell death (PCD). Cell death in self-renewing tissues, such as the skin, gut, and bone marrow, is necessary to make room for the billions of new cells produced daily. So massive is the flux of cells through our bodies that, in a typical year, each of us will produce and, in parallel, eradicate a mass of cells equal to almost our entire body weight. The morphologic ritual cells go through when experiencing PCD has been termed apoptosis and is executed by a family of intracellular proteases, called caspases. Unlike accidental cell deaths caused by infarction and trauma, these physiologic deaths culminate in fragmentation of cells into membrane-encased bodies which are cleared through phagocytosis by neighboring cells without inciting inflammatory reactions or tissue scarring. Defects in the processes controlling PCD can extend cell life span, contributing to neoplastic cell expansion independently of cell division. Moreover, failures in normal apoptosis pathways contribute to carcinogenesis by creating a permissive environment for genetic instability and accumulation of gene mutations, promoting resistance to immune-based destruction, allowing disobeyance of cell cycle checkpoints that would normally induce apoptosis, facilitating growth factor/hormone–independent cell survival, supporting anchorage-independent survival during metastasis, reducing dependence on oxygen and nutrients, and conferring resistance to cytotoxic anticancer drugs and radiation. Elucidation of the genes that constitute the core machinery of the cell death pathway has provided new insights into tumor biology, revealing novel strategies for combating cancer.
C-Kit is a receptor tyrosine kinase that binds stem cell factor. Substitution of valine for aspartic acid 816 (V816) constitutively activates human c-Kit and this mutation is found in patients with mastocytosis, leukemia and germ cells tumors. Transduction of immortalized murine progenitor cells with wild-type c-Kit (MIHC-Kit) results in stem cell factor-induced growth (SCF), while cells expressing V816 c-Kit (MIHC-V816) are factor-independent and tumorigenic. The mechanisms mediating transformation by V816 c-Kit are unknown. SCF activates Erk 1, Erk2 and P13 kinase in MIHC-Kit cells, and P13 kinase contributes to activation of Akt and Jnks. In MIHC-V816 cells, P13 kinase, Jnk 1 and Jnk 2 were activated, but Akt, Erk 1 and Erk 2 were not. Thus, V816 c-Kit constitutively activates P13 kinase, but not all signaling pathways activated by wild-type c-Kit. Further, pathways downstream of P13 kinase are altered in MIHC-V816 cells. Studies with a P13 kinase inhibitor and V816/F721 c-Kit, a mutant incapable of recruiting P13 kinase, indicate that constitutive activation of P13 kinase plays a role in factor-independent growth mediated by V816 c-Kit and is critical for tumorigenicity of MIHC. These data are the first to demonstrate the role of P13 kinase in transformation of hematopoietic cells by this oncogenic c-Kit mutant.