Cellular functions regulated by Src family kinases

A FRET-Based Biosensor for the Src N-Terminal Regulatory Element

In signaling proteins, intrinsically disordered regions often represent regulatory elements, which are sensitive to environmental effects, ligand binding, and post-translational modifications. The conformational space sampled by disordered regions can be affected by environmental stimuli and these changes trigger, vis a vis effector domain, downstream processes. The disordered nature of these regulatory elements enables signal integration and graded responses but prevents the application of classical approaches for drug screening based on the existence of a fixed three-dimensional structure. We have designed a genetically encodable biosensor for the N-terminal regulatory element of the c-Src kinase, the first discovered protooncogene and lead representative of the Src family of kinases. The biosensor is formed by two fluorescent proteins forming a FRET pair fused at the two extremes of a construct including the SH4, unique and SH3 domains of Src. An internal control is provided by an engineered proteolytic site allowing the generation of an identical mixture of the disconnected fluorophores. We show FRET variations induced by ligand binding. The biosensor has been used for a high-throughput screening of a library of 1669 compounds with seven hits confirmed by NMR.

Mechanoregulation of Vascular Endothelial Growth Factor Receptor 2 in Angiogenesis

The endothelial cells that compose the vascular system in the body display a wide range of mechanotransductive behaviors and responses to biomechanical stimuli, which act in concert to control overall blood vessel structure and function. Such mechanosensitive activities allow blood vessels to constrict, dilate, grow, or remodel as needed during development as well as normal physiological functions, and the same processes can be dysregulated in various disease states. Mechanotransduction represents cellular responses to mechanical forces, translating such factors into chemical or electrical signals which alter the activation of various cell signaling pathways. Understanding how biomechanical forces drive vascular growth in healthy and diseased tissues could create new therapeutic strategies that would either enhance or halt these processes to assist with treatments of different diseases. In the cardiovascular system, new blood vessel formation from preexisting vasculature, in a process known as angiogenesis, is driven by vascular endothelial growth factor (VEGF) binding to VEGF receptor 2 (VEGFR-2) which promotes blood vessel development. However, physical forces such as shear stress, matrix stiffness, and interstitial flow are also major drivers and effectors of angiogenesis, and new research suggests that mechanical forces may regulate VEGFR-2 phosphorylation. In fact, VEGFR-2 activation has been linked to known mechanobiological agents including ERK/MAPK, c-Src, Rho/ROCK, and YAP/TAZ. In vascular disease states, endothelial cells can be subjected to altered mechanical stimuli which affect the pathways that control angiogenesis. Both normalizing and arresting angiogenesis associated with tumor growth have been strategies for anti-cancer treatments. In the field of regenerative medicine, harnessing biomechanical regulation of angiogenesis could enhance vascularization strategies for treating a variety of cardiovascular diseases, including ischemia or permit development of novel tissue engineering scaffolds. This review will focus on the impact of VEGFR-2 mechanosignaling in endothelial cells (ECs) and its interaction with other mechanotransductive pathways, as well as presenting a discussion on the relationship between VEGFR-2 activation and biomechanical forces in the extracellular matrix (ECM) that can help treat diseases with dysfunctional vascular growth.

The inhibition of Panc1 cancer cells invasion by hAMSCs secretome through suppression of tyrosine phosphorylation of SGK223 (at Y411 site), c-Src (at Y416, Y530 sites), AKT activity, and JAK1/Stat3 signaling

SGK223 is a scaffolding protein involving in the oncogenic tyrosine kinase signaling. SGK223 was phosphorylated at Y411 by c-Src and in response to the Epidermal growth factor receptor (EGFR). Tyrosine phosphorylated SGK223 at Y411 enables to interact with CSK resulting up regulation of c-Src activity and promotion of the cell migration. Human amniotic mesenchymal stromal cells (hAMSCs) are a population of multipotent cells that it was considered to be as a potential platform in cancer therapy. Herein, we employed a co-culture system to clarify the effects of hAMSCs secretome through tyrosine phosphorylation of c-Src, SGK223, AKT activity, and JAK1/Stat3 signaling in Panc1 pancreatic cancer cells. By using the 0.4 μm pore sized transwell membranes, both cell lines were firstly co-cultured for 72 h. Next, c-Src activity (tyrosine phosphorylation levels at Y530 and Y416), tyrosine phosphorylation level of SGK223 (at Y411), AKT activity, and JAK1/Stat3 signaling in Panc1 cells after treatment with hAMSCs were evaluated. Our results showed that hAMSCs have the inhibitory effects on Panc1 pancreatic cancer cells invasion and it suggests that the suppression of c-Src activity, SGK223 expression, AKT activity, and JAK1/Stat3 signaling may be as critical targets in pancreatic cancer therapy.

To Stick or Not to Stick: Adhesions in Orofacial Clefts

Morphogenesis requires a tight coordination between mechanical forces and biochemical signals to inform individual cellular behavior. For these developmental processes to happen correctly the organism requires precise spatial and temporal coordination of the adhesion, migration, growth, differentiation, and apoptosis of cells originating from the three key embryonic layers, namely the ectoderm, mesoderm, and endoderm. The cytoskeleton and its remodeling are essential to organize and amplify many of the signaling pathways required for proper morphogenesis. In particular, the interaction of the cell junctions with the cytoskeleton functions to amplify the behavior of individual cells into collective events that are critical for development. In this review we summarize the key morphogenic events that occur during the formation of the face and the palate, as well as the protein complexes required for cell-to-cell adhesions. We then integrate the current knowledge into a comprehensive review of how mutations in cell-to-cell adhesion genes lead to abnormal craniofacial development, with a particular focus on cleft lip with or without cleft palate.

Signaling by the tyrosine kinase Yes promotes liver cancer development

Most patients with hepatocellular carcinoma (HCC) are diagnosed at a late stage and have few therapeutic options and a poor prognosis. This is due to the lack of clearly defined underlying mechanisms or a dominant oncogene that can be targeted pharmacologically, unlike in other cancer types. Here, we report the identification of a previously uncharacterized oncogenic signaling pathway in HCC that is mediated by the tyrosine kinase Yes. Using genetic and pharmacological interventions in cellular and mouse models of HCC, we showed that Yes activity was necessary for HCC cell proliferation. Transgenic expression of activated Yes in mouse hepatocytes was sufficient to induce liver tumorigenesis. Yes phosphorylated the transcriptional coactivators YAP and TAZ (YAP/TAZ), promoting their nuclear accumulation and transcriptional activity in HCC cells and liver tumors. We also showed that YAP/TAZ were effectors of the Yes-dependent oncogenic transformation of hepatocytes. Src family kinase activation correlated with the tyrosine phosphorylation and nuclear localization of YAP in human HCC and was associated with increased tumor burden in mice. Specifically, high Yes activity predicted shorter overall survival in patients with HCC. Thus, our findings identify Yes as a potential therapeutic target in HCC.

The Rho guanine nucleotide exchange factor PLEKHG1 is activated by interaction with and phosphorylation by Src family kinase member FYN

Rho family small GTPases (Rho) regulate various cell motility processes by spatiotemporally controlling the actin cytoskeleton. Some Rho-specific guanine nucleotide exchange factors (RhoGEFs) are regulated via tyrosine phosphorylation by Src family tyrosine kinase (SFK). We also previously reported that PLEKHG2, a RhoGEF for the GTPases Rac1 and Cdc42, is tyrosine-phosphorylated by SRC. However, the details of the mechanisms by which SFK regulates RhoGEFs are not well understood. In this study, we found for the first time that PLEKHG1, which has very high homology to the Dbl and pleckstrin homology domains of PLEKHG2, activates Cdc42 following activation by FYN, a member of the SFK family. We also show that this activation of PLEKHG1 by FYN requires interaction between these two proteins and FYN-induced tyrosine phosphorylation of PLEKHG1. We also found that the region containing the Src homology 3 and Src homology 2 domains of FYN is required for this interaction. Finally, we demonstrated that tyrosine phosphorylation of Tyr-720 and Tyr-801 in PLEKHG1 is important for the activation of PLEKHG1. These results suggest that FYN is a regulator of PLEKHG1 and may regulate cell morphology through Rho signaling via the interaction with and tyrosine phosphorylation of PLEKHG1.

Roles of matrix metalloproteinases in development, immunology, and ovulation in fruit Fly (Drosophila)

Matrix metalloproteinase (MMP), a protease enzyme, participates in proteolytic cleavage of extracellular matrix proteins from Drosophila and mammals. But, recent studies have revealed other physiologically important roles of MMP in Drosophila. MMP contributes to cardioblast movement and distribution of collagen proteins during cardiogenesis in developing Drosophila. Tissue remodeling, especially tracheal development is also maintained by MMP. MMP regulates certain immunological functions in Drosophila such as wound repairing, plasmatocyte assemblage at the injured site of the basement membrane and glial response to axon degeneration in Drosophila nervous system. But, the contribution of MMP to tumor formation and metastasis in Drosophila has made it an interesting topic among researchers. Ovulation and egg laying are also found to be affected positively by MMP in Drosophila.

Depletion of Janus kinase-2 promotes neuronal differentiation of mouse embryonic stem cells

Janus kinase 2 (JAK2), a non-receptor tyrosine kinase, is a critical component of cytokine and growth factor signaling pathways regulating hematopoietic cell proliferation. JAK2 mutations are associated with multiple myeloproliferative neoplasms. Although physiological and pathological functions of JAK2 in hematopoietic tissues are well-known, such functions of JAK2 in the nervous system are not well studied yet. The present study demonstrated that JAK2 could negatively regulate neuronal differentiation of mouse embryonic stem cells (ESCs). Depletion of JAK2 stimulated neuronal differentiation of mouse ESCs and activated glycogen synthase kinase 3β, Fyn, and cyclin-dependent kinase 5. Knockdown of JAK2 resulted in accumulation of GTP-bound Rac1, a Rho GTPase implicated in the regulation of cytoskeletal dynamics. These findings suggest that JAK2 might negatively regulate neuronal differentiation by suppressing the GSK-3β/Fyn/CDK5 signaling pathway responsible for morphological maturation.

The Potential Role of Curcumin in Modulating the Master Antioxidant Pathway in Diabetic Hypoxia-Induced Complications

Oxidative stress is the leading player in the onset and development of various diseases. The Keap1-Nrf2 pathway is a pivotal antioxidant system that preserves the cells' redox balance. It decreases inflammation in which the nuclear trans-localization of Nrf2 as a transcription factor promotes various antioxidant responses in cells. Through some other directions and regulatory proteins, this pathway plays a fundamental role in preventing several diseases and reducing their complications. Regulation of the Nrf2 pathway occurs on transcriptional and post-transcriptional levels, and these regulations play a significant role in its activity. There is a subtle correlation between the Nrf2 pathway and the pivotal signaling pathways, including PI3 kinase/AKT/mTOR, NF-κB and HIF-1 factors. This demonstrates its role in the development of various diseases. Curcumin is a yellow polyphenolic compound from Curcuma longa with multiple bioactivities, including antioxidant, anti-inflammatory, anti-tumor, and anti-viral activities. Since hyperglycemia and increased reactive oxygen species (ROS) are the leading causes of common diabetic complications, reducing the generation of ROS can be a fundamental approach to dealing with these complications. Curcumin can be considered a potential treatment option by creating an efficient therapeutic to counteract ROS and reduce its detrimental effects. This review discusses Nrf2 pathway regulation at different levels and its correlation with other important pathways and proteins in the cell involved in the progression of diabetic complications and targeting these pathways by curcumin.

Dasatinib-Induced Nephrotic Syndrome: A Case Report

Second-generation tyrosine kinase inhibitors (TKI), such as nilotinib and dasatinib, are used in the first-line treatment of chronic myeloid leukemia (CML), usually after the failure or resistance to imatinib. Despite a good safety profile, medications in this category have an increased incidence of specific adverse events such as pulmonary hypertension, pleural effusion, and cardiovascular/peripheral arterial events. However, renal complications are rarely reported and observed. We herein report a case of a 46-year-old patient with CML who developed nephrotic syndrome upon switching from imatinib to dasatinib therapy, with the resolution of symptoms upon treatment discontinuation and switching to nilotinib. Limited cases were reported in the literature. It is thought that the inhibition of the vascular endothelial growth factor (VEGF) pathway is the main mechanism leading to proteinuria. Dasatinib-induced nephrotic syndrome should be looked for as it can be resolved by either reducing the dose or stopping it altogether and switching to another TKI.

T cell receptor (TCR) signaling in health and disease

Interaction of the T cell receptor (TCR) with an MHC-antigenic peptide complex results in changes at the molecular and cellular levels in T cells. The outside environmental cues are translated into various signal transduction pathways within the cell, which mediate the activation of various genes with the help of specific transcription factors. These signaling networks propagate with the help of various effector enzymes, such as kinases, phosphatases, and phospholipases. Integration of these disparate signal transduction pathways is done with the help of adaptor proteins that are non-enzymatic in function and that serve as a scaffold for various protein-protein interactions. This process aids in connecting the proximal to distal signaling pathways, thereby contributing to the full activation of T cells. This review provides a comprehensive snapshot of the various molecules involved in regulating T cell receptor signaling, covering both enzymes and adaptors, and will discuss their role in human disease.

Src activates retrograde membrane traffic through phosphorylation of GBF1

The Src tyrosine kinase controls cancer-critical protein glycosylation through Golgi to ER relocation of GALNTs enzymes. How Src induces this trafficking event is unknown. Golgi to ER transport depends on the GTP exchange factor (GEF) GBF1 and small GTPase Arf1. Here, we show that Src induces the formation of tubular transport carriers containing GALNTs. The kinase phosphorylates GBF1 on 10 tyrosine residues; two of them, Y876 and Y898, are located near the C-terminus of the Sec7 GEF domain. Their phosphorylation promotes GBF1 binding to the GTPase; molecular modeling suggests partial melting of the Sec7 domain and intramolecular rearrangement. GBF1 mutants defective for these rearrangements prevent binding, carrier formation, and GALNTs relocation, while phosphomimetic GBF1 mutants induce tubules. In sum, Src promotes GALNTs relocation by promoting GBF1 binding to Arf1. Based on residue conservation, similar regulation of GEF-Arf complexes by tyrosine phosphorylation could be a conserved and widespread mechanism.

Src family kinases inhibit differentiation of intestinal epithelial cells through the Hippo effector YAP1

Intestinal cell lineage differentiation is a tightly regulated mechanism that involves several intracellular signaling pathways affecting the expression of a variety of transcription factors, which ultimately regulate cell specific gene expression. Absorptive and goblet cells are the two main epithelial cell types of the intestine. Previous studies from our group using an shRNA knockdown approach have shown that YAP1, one of the main Hippo pathway effectors, inhibits the differentiation of these two cell types. In the present study, we show that YAP1 activity is regulated by Src family kinases (SFKs) in these cells. Inhibition of SFKs led to a sharp reduction in YAP1 expression at the protein level, an increase in CDX2 and the P1 forms of HNF4α and of absorptive and goblet cell differentiation specific markers. Interestingly, in Caco-2/15 cells which express both YAP1 and its paralog TAZ, TAZ was not reduced by the inhibition of SFKs and its specific knockdown rather impaired absorptive cell differentiation indicating that YAP1 and TAZ are not always interchangeable for regulating cell functions. This article has an associated First Person interview with the first author of the paper.

Colchicine protects against cartilage degeneration by inhibiting MMP13 expression via PLC-γ1 phosphorylation

OBJECTIVE

Low molecular weight compounds that reduce the expression of MMP13 at the mRNA level might serve as disease-modifying osteoarthritis (OA) drugs (DMOADs). The objective of this study was to identify a candidate DMOAD that targets MMP13 expression.

DESIGN

High-throughput screening was performed to identify compounds that suppress inflammatory cytokine-induced MMP13 expression. Ingenuity pathway analysis (IPA) using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomic analysis was conducted to identify signaling pathways related to cytokines. MMP13 expression in chondrocytes was evaluated through RT-qPCR and western blotting analyses. Additionally, 10-week-old mice were subjected to destabilization of the medial meniscus (DMM) surgery to induce OA and were sacrificed 12 weeks post-surgery for pathological examination. OA was evaluated using the OARSI scoring system.

RESULTS

Colchicine was identified as a DMOAD candidate as it inhibited inflammatory cytokine-induced MMP13 expression in vitro, and the colchicine-administered mice with DMM presented significantly lower OARSI scores (adjusted P: 0.0242, mean difference: 1.6, 95% confidence interval (CI) of difference: 0.1651-3.035) and significantly lower synovial membrane inflammation scores (adjusted P: 0.0243, mean difference: 0.6, 95% CI of difference: 0.06158-1.138) than mice with DMM. IPA further revealed that components of the Rho signaling pathways are regulated by cytokines and colchicine. IL-1β and TNF-α activate RAC1 and SRC signals, respectively, leading to the phosphorylation of PLC-γ1 and synergistic induction of MMP13 expression. Most notably, colchicine abrogates inflammatory cytokine-induced phosphorylation of PLC-γ1, leading to the induction of MMP13 expression.

CONCLUSIONS

Colchicine is a potential DMOAD candidate that inhibits MMP13 expression and consequent cartilage degradation by disrupting the SRC/RAC1-phospho-PLCγ1-Ca2+ signaling pathway.

Dynamics of Post-Translational Modification Inspires Drug Design in the Kinase Family

Post-translational modification (PTM) on protein plays important roles in the regulation of cellular function and disease pathogenesis. The systematic analysis of PTM dynamics presents great opportunities to enlarge the target space by PTM allosteric regulation. Here, we presented a framework by integrating the sequence, structural topology, and particular dynamics features to characterize the functional context and druggabilities of PTMs in the well-known kinase family. The machine learning models with these biophysical features could successfully predict PTMs. On the other hand, PTMs were identified to be significantly enriched in the reported allosteric pockets and the allosteric potential of PTM pockets were thus proposed through these biophysical features. In the end, the covalent inhibitor DC-Srci-6668 targeting the PTM pocket in c-Src kinase was identified, which inhibited the phosphorylation and locked c-Src in the inactive state. Our findings represent a crucial step toward PTM-inspired drug design in the kinase family.

Biosensors based on peptide exposure show single molecule conformations in live cells

We describe an approach to study the conformation of individual proteins during single particle tracking (SPT) in living cells. "Binder/tag" is based on incorporation of a 7-mer peptide (the tag) into a protein where its solvent exposure is controlled by protein conformation. Only upon exposure can the peptide specifically interact with a reporter protein (the binder). Thus, simple fluorescence localization reflects protein conformation. Through direct excitation of bright dyes, the trajectory and conformation of individual proteins can be followed. Simple protein engineering provides highly specific biosensors suitable for SPT and FRET. We describe tagSrc, tagFyn, tagSyk, tagFAK, and an orthogonal binder/tag pair. SPT showed slowly diffusing islands of activated Src within Src clusters and dynamics of activation in adhesions. Quantitative analysis and stochastic modeling revealed in vivo Src kinetics. The simplicity of binder/tag can provide access to diverse proteins.

Characterization of Phosphorylation Status and Kinase Activity of Src Family Kinases Expressed in Cell-Based and Cell-Free Protein Expression Systems

The production of heterologous proteins is an important procedure for biologists in basic and applied sciences. A variety of cell-based and cell-free protein expression systems are available to achieve this. The expression system must be selected carefully, especially for target proteins that require post-translational modifications. In this study, human Src family kinases were prepared using six different protein expression systems: 293 human embryonic kidney cells, Escherichia coli, and cell-free expression systems derived from rabbit reticulocytes, wheat germ, insect cells, or Escherichia coli. The phosphorylation status of each kinase was analyzed by Phos-tag SDS-PAGE. The kinase activities were also investigated. In the eukaryotic systems, multiple phosphorylated forms of the expressed kinases were observed. In the rabbit reticulocyte lysate system and 293 cells, differences in phosphorylation status between the wild-type and kinase-dead mutants were observed. Whether the expressed kinase was active depended on the properties of both the kinase and each expression system. In the prokaryotic systems, Src and Hck were expressed in autophosphorylated active forms. Clear differences in post-translational phosphorylation among the protein expression systems were revealed. These results provide useful information for preparing functional proteins regulated by phosphorylation.

Plasminogen activator receptor assemblies in cell signaling, innate immunity, and inflammation

Tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) are serine proteases and major activators of fibrinolysis in mammalian systems. Because fibrinolysis is an essential component of the response to tissue injury, diverse cells, including cells that participate in the response to injury, have evolved receptor systems to detect tPA and uPA and initiate appropriate cell-signaling responses. Formation of functional receptor systems for the plasminogen activators requires assembly of diverse plasma membrane proteins, including but not limited to: the urokinase receptor (uPAR); integrins; N-formyl peptide receptor-2 (FPR2), receptor tyrosine kinases (RTKs), the N-methyl-d-aspartate receptor (NMDA-R), and low-density lipoprotein receptor-related protein-1 (LRP1). The cell-signaling responses elicited by tPA and uPA impact diverse aspects of cell physiology. This review describes rapidly evolving knowledge regarding the structure and function of plasminogen activator receptor assemblies. How these receptor assemblies regulate innate immunity and inflammation is then considered.

Investigation of inhibition effect of daidzein on osteosarcoma cells based on experimental validation and systematic pharmacology analysis

Objective

This study aims to explore the effect of daidzein, which is a natural isoflavone compound mainly extracted from soybeans, on osteosarcoma and the potential molecular mechanism.

Material and Methods

143B and U2OS osteosarcoma cells were treated with gradient concentrations of daidzein, and MTT assay was used to determine the cell proliferation capacity and IC₅₀. Hoechst 33342 staining and Annexin V-FITC/PI detection were used to determine apoptosis. Cell cycle was analyzed by flow cytometry, and migration ability were detected by transwell assays and scratch wound assay. An osteosarcoma xenograft mice model was applied to investigate the effect of daidzein on osteosarcoma in vivo. Systematic pharmacology and molecular modeling analysis were applied to predict the target of daidzein to osteosarcoma, and the target Src was verified by western blotting. We also observed the effect of daidzein on cell proliferation and apoptosis of Src-overexpressing osteosarcoma cells.

Results

In vitro, daidzein significantly inhibited 143B and U2OS osteosarcoma cell proliferation and migration, and induced cell cycle arrest. In vivo, daidzein exerts antitumor effects in osteosarcoma xenograft mice. After systematic screening and analysis, Src-MAPK signaling pathway was predicted as the highest-ranked pathway. Western blot demonstrated that daidzein inhibited phosphorylation of the Src-ERK pathway in osteosarcoma cells. Also, overexpression of Src could partially reverse the inhibitory effects of daidzein on osteosarcoma cell proliferation.

Conclusion

Daidzein exerts an antitumor effect on osteosarcoma, and the mechanism may be through the Src-ERK pathway.

Anesthesia can alter the levels of corticosterone and the phosphorylation of signaling molecules

Objective

Neuroscience research using laboratory animals has increased over the years for a number of reasons. Some of these studies require the use of anesthetics for surgical procedures. However, the use of anesthetics promotes several physiological changes that may interfere with experimental results. Although the anesthetics and methods of delivery used to vary, one of the most common is ketamine associated with another compound such as xylazine. We aimed to evaluate the effect of ketamine and xylazine (KX) on corticosterone levels and on the degree of phosphorylation of p44/42 (ERK1/2), Src kinases and calcium/calmodulin-dependent kinase II (CAMKII). We also compared the effects of KX on sleep deprivation, which is known to affect the hormonal profile including corticosterone.

Results

We found that the use of KX can increase corticosterone levels and alter the degree of phosphorylation of signaling proteins.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05763-w.

Focal segmental glomerulosclerosis and concurrent glomerular microangiopathy after long-term imatinib administration

A 79-year-old Japanese man was admitted to our hospital because of proteinuria and kidney dysfunction. He was diagnosed with chronic myeloid leukemia 13 years before and was treated with imatinib. Deep molecular response was achieved but he developed 1+ proteinuria in the first year, which gradually worsened thereafter. Imatinib was discontinued 12 years later but proteinuria and kidney dysfunction were progressive. Percutaneous kidney biopsy revealed mild mesangial hyper-cellularity and matrix increase, swelling of endothelial cells, and partial double contours of glomerular tufts. Subendothelial edema in the interlobular artery was also noted. Immunofluorescence was not remarkable. Electron microscopy revealed endothelial injury with severe sub-endothelial edema. Since imatinib had already been discontinued, conservative therapy with maximal dose of azilsartan was administered. A second biopsy was performed 1 year later because of further deterioration of kidney function, which revealed markedly increased global glomerulosclerosis and severe interstitial fibrosis and tubular atrophy. Segmental glomerulosclerosis with podocyte hyperplasia was also observed. Electron microscopy revealed glomerulosclerotic changes and partially attenuated endothelial injury. Two and a half years later, proteinuria reduced, progression of kidney dysfunction slowed, and he was independent on dialysis therapy. Molecular response of chronic myeloid leukemia was also maintained. The clinical course suggested that endothelial and podocyte injuries were induced by imatinib, and that the nephrotoxic effects lasted for a few years after discontinuation.

The Radiosensitizing Effect of AZD0530 in Glioblastoma and Glioblastoma Stem-Like Cells

AZD0530, a potent small-molecule inhibitor of the Src kinase family, is an anticancer drug used in the treatment of various cancers. In the case of glioblastoma (GBM), where resistance to radiotherapy frequently occurs, Src kinase is known as one of the molecules responsible for imparting radioresistance to GBM. Thus, we evaluated the effect of AZD0530 on the radiosensitivity of human GBM cells and human glioblastoma stem-like cells (GSCs). We show that Src activity of GBM and GSC is increased by radiation and inhibited by AZD0530, and using clonogenic assays, AZD0530 enhances the radiosensitivity of GBM and GSCs. Also, AZD0530 induced a prolongation of radiation-induced γH2AX without specific cell cycle and mitotic index changes, suggesting that AZD0530-induced radiosensitization in GBM cells and GSCs results from the inhibition of DNA repair. In addition, AZD0530 was shown to inhibit the radiation-induced EGFR/PI3K/AKT pathway, which is known to promote and regulate radioresistance and survival of GBM cells by radiation. Finally, mice bearing orthotopic xenografts initiated from GBM cells were then used to evaluate the in vivo response to AZD0530 and radiation. The combination of AZD0530 and radiation showed the longest median survival compared with any single modality. Thus, these results show that AZD0530 enhances the radiosensitivity of GBM cells and GSCs and suggest the possibility of AZD0530 as a clinical radiosensitizer for treatment of GBM.

Co-receptor signaling in the pathogenesis of neuroHIV

The HIV co-receptors, CCR5 and CXCR4, are necessary for HIV entry into target cells, interacting with the HIV envelope protein, gp120, to initiate several signaling cascades thought to be important to the entry process. Co-receptor signaling may also promote the development of neuroHIV by contributing to both persistent neuroinflammation and indirect neurotoxicity. But despite the critical importance of CXCR4 and CCR5 signaling to HIV pathogenesis, there is only one therapeutic (the CCR5 inhibitor Maraviroc) that targets these receptors. Moreover, our understanding of co-receptor signaling in the specific context of neuroHIV is relatively poor. Research into co-receptor signaling has largely stalled in the past decade, possibly owing to the complexity of the signaling cascades and functions mediated by these receptors. Examining the many signaling pathways triggered by co-receptor activation has been challenging due to the lack of specific molecular tools targeting many of the proteins involved in these pathways and the wide array of model systems used across these experiments. Studies examining the impact of co-receptor signaling on HIV neuropathogenesis often show activation of multiple overlapping pathways by similar stimuli, leading to contradictory data on the effects of co-receptor activation. To address this, we will broadly review HIV infection and neuropathogenesis, examine different co-receptor mediated signaling pathways and functions, then discuss the HIV mediated signaling and the differences between activation induced by HIV and cognate ligands. We will assess the specific effects of co-receptor activation on neuropathogenesis, focusing on neuroinflammation. We will also explore how the use of substances of abuse, which are highly prevalent in people living with HIV, can exacerbate the neuropathogenic effects of co-receptor signaling. Finally, we will discuss the current state of therapeutics targeting co-receptors, highlighting challenges the field has faced and areas in which research into co-receptor signaling would yield the most therapeutic benefit in the context of HIV infection. This discussion will provide a comprehensive overview of what is known and what remains to be explored in regard to co-receptor signaling and HIV infection, and will emphasize the potential value of HIV co-receptors as a target for future therapeutic development.

GSK-3β, FYN, and DYRK1A: Master Regulators in Neurodegenerative Pathways

Protein kinases (PKs) have been recognized as central nervous system (CNS)-disease-relevant targets due to their master regulatory role in different signal transduction cascades in the neuroscience space. Among them, GSK-3β, FYN, and DYRK1A play a crucial role in the neurodegeneration context, and the deregulation of all three PKs has been linked to different CNS disorders with unmet medical needs, including Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal lobar degeneration (FTLD), and several neuromuscular disorders. The multifactorial nature of these diseases, along with the failure of many advanced CNS clinical trials, and the lengthy approval process of a novel CNS drug have strongly limited the CNS drug discovery. However, in the near-decade from 2010 to 2020, several computer-assisted drug design strategies have been combined with synthetic efforts to develop potent and selective GSK-3β, FYN, and DYRK1A inhibitors as disease-modifying agents. In this review, we described both structural and functional aspects of GSK-3β, FYN, and DYRK1A and their involvement and crosstalk in different CNS pathological signaling pathways. Moreover, we outlined attractive medicinal chemistry approaches including multi-target drug design strategies applied to overcome some limitations of known PKs inhibitors and discover improved modulators with suitable blood-brain barrier (BBB) permeability and drug-like properties.

Src family kinases involved in the differentiation of human preadipocytes

BACKGROUND

Obesity is characterized by the excess accumulation of white adipose tissue (WAT). Src family kinases (SFKs) are non-receptor tyrosine kinases consisting of eight members (SRC, FYN, YES1, HCK, LCK, LYN, FGR and BLK) that have been studied extensively in mammalian cells. Although individual members in murine cells provide some clues that are associated with the regulation of adipogenesis, the specific role of this family in adipocyte differentiation has rarely been assessed, especially in human adipocytes.

METHODS

Herein, we first explored the expression profiles of SFKs during human preadipocyte differentiation. Then, we used the pyrazolo-pyrimidinyl-amine compound PP1, a potent SFK inhibitor, to evaluate the function of SFKs during adipocyte differentiation. Furthermore, we adopted a loss-of-function strategy with siRNAs to determine the role of FGR in adipocyte differentiation.

RESULTS

Here, we found that SRC, FYN, YES1, LYN and FGR were expressed in human preadipocytes and induced after the initiation of differentiation. Furthermore, the SFK inhibitor PP1 suppressed adipocyte differentiation. We also found that PP1 significantly suppressed the SFK activity in preadipocytes and decreased the expression of adipogenic genes in early and late differentiation. Given that FGR exhibited the most expression enhancement in mature adipocytes, we focused on FGR and found that its knockdown reduced lipid accumulation and adipogenic gene expression.

CONCLUSIONS

Collectively, these findings suggest that SFKs, especially FGR, are involved in the differentiation of human preadipocytes. Our results lay a foundation for further understanding the role of SFKs in adipocyte differentiation and provide new clues for anti-obesity therapies.

Dasatinib‐induced chylothorax: An unusual presentation of a common adverse event—A case report with literature review

Tyrosine kinase inhibitors (TKIs) are the key agents for treating CML and BCR–ABL⁺ B‐ALL. Dasatinib is a potent second‐generation TKI. Here, we have discussed the case of a 51‐year‐old gentleman diagnosed with B‐myeloid mixed‐phenotype acute leukemia with t(9;22)(q34.1;q11.2); BCR–ABL1p210, in complete hematological, cytogenetic, and molecular remission, who developed chylothorax. Though pleural effusion is a commonly observed adverse effect of dasatinib therapy, chylothorax is rare. The ability of Dasatinib to inhibit multiple families of tyrosine kinases could be considered the etiology. Discontinuation of the drug resolved the symptom, but pleural effusion recurred once Dasatinib was resumed. Chylothorax induced by Dasatinib is a differential to be kept in mind, owing to the limited number of cases being reported.

Implications of a 'Third Signal' in NK Cells

Innate and adaptive immune systems are evolutionarily divergent. Primary signaling in T and B cells depends on somatically rearranged clonotypic receptors. In contrast, NK cells use germline-encoded non-clonotypic receptors such as NCRs, NKG2D, and Ly49H. Proliferation and effector functions of T and B cells are dictated by unique peptide epitopes presented on MHC or soluble humoral antigens. However, in NK cells, the primary signals are mediated by self or viral proteins. Secondary signaling mediated by various cytokines is involved in metabolic reprogramming, proliferation, terminal maturation, or memory formation in both innate and adaptive lymphocytes. The family of common gamma (γc) cytokine receptors, including IL-2Rα/β/γ, IL-7Rα/γ, IL-15Rα/β/γ, and IL-21Rα/γ are the prime examples of these secondary signals. A distinct set of cytokine receptors mediate a ‘third’ set of signaling. These include IL-12Rβ1/β2, IL-18Rα/β, IL-23R, IL-27R (WSX-1/gp130), IL-35R (IL-12Rβ2/gp130), and IL-39R (IL-23Rα/gp130) that can prime, activate, and mediate effector functions in lymphocytes. The existence of the ‘third’ signal is known in both innate and adaptive lymphocytes. However, the necessity, context, and functional relevance of this ‘third signal’ in NK cells are elusive. Here, we define the current paradigm of the ‘third’ signal in NK cells and enumerate its clinical implications.

Purification of a Src family tyrosine protein kinase from bovine retinas

Since tyrosine phosphorylation appears to play important functions in photoreceptor cells, we searched here for retinal nonreceptor tyrosine kinases of the Src family. We demonstrated that Src family tyrosine kinases were present in the cytosolic fraction of extracted bovine retinas. A Src family tyrosine kinase with an apparent molecular mass of about 62 kDa was purified to homogeneity from the soluble fraction of dark-adapted bovine retinas after three consecutive purification steps: ω-aminooctyl-agarose hydrophobic chromatography, Cibacron blue 3GA-agarose pseudo-affinity chromatography, and α-casein-agarose affinity chromatography. The purified protein was subjected to N-terminal amino acid sequencing and the sequence Gly-Ile-Ile-Lys-Ser-Glu-Glu was obtained, which displayed homology with the first seven residues of the Src family tyrosine kinase c-Yes from Bos taurus (Gly-Cys-Ile-Lys-Ser-Lys-Glu). Although the cytosolic fraction from dark-adapted retinas contained tyrosine kinases of the Src family capable of phosphorylating the α-subunit of transducin, which is the heterotrimeric G protein involved in phototransduction, the purified tyrosine kinase was not capable of using transducin as a substrate. The cellular role of this retinal Src family member remains to be found.

Sublethal doxorubicin promotes migration and invasion of breast cancer cells: role of Src Family non-receptor tyrosine kinases

BACKGROUND

Doxorubicin (Dox) is a widely used chemotherapy, but its effectiveness is limited by dose-dependent side effects. Although lower Dox doses reduce this risk, studies have reported higher recurrence of local disease with no improvement in survival rate in patients receiving low doses of Dox. To effectively mitigate this, a better understanding of the adverse effects of suboptimal Dox doses is needed.

METHODS

Effects of sublethal dose of Dox on phenotypic changes were assessed with light and confocal microscopy. Migratory and invasive behavior were assessed by wound healing and transwell migration assays. MTT and LDH release assays were used to analyze cell growth and cytotoxicity. Flow cytometry was employed to detect cell surface markers of cancer stem cell population. Expression and activity of matrix metalloproteinases were probed with qRT-PCR and zymogen assay. To identify pathways affected by sublethal dose of Dox, exploratory RNAseq was performed and results were verified by qRT-PCR in multiple cell lines (MCF7, ZR75-1 and U-2OS). Regulation of Src Family kinases (SFK) by key players in DNA damage response was assessed by siRNA knockdown along with western blot and qRT-PCR. Dasatinib and siRNA for Fyn and Yes was employed to inhibit SFKs and verify their role in increased migration and invasion in MCF7 cells treated with sublethal doses of Dox.

RESULTS

The results show that sublethal Dox treatment leads to increased migration and invasion in otherwise non-invasive MCF7 breast cancer cells. Mechanistically, these effects were independent of the epithelial mesenchymal transition, were not due to increased cancer stem cell population, and were not observed with other chemotherapies. Instead, sublethal Dox induces expression of multiple SFK-including Fyn, Yes, and Src-partly in a p53 and ATR-dependent manner. These effects were validated in multiple cell lines. Functionally, inhibiting SFKs with Dasatinib and specific downregulation of Fyn suppressed Dox-induced migration and invasion of MCF7 cells.

CONCLUSIONS

Overall, this study demonstrates that sublethal doses of Dox activate a pro-invasive, pro-migration program in cancer cells. Furthermore, by identifying SFKs as key mediators of these effects, our results define a potential therapeutic strategy to mitigate local invasion through co-treatment with Dasatinib.

Reduced efficacy of a Src kinase inhibitor in crowded protein solution

The inside of a cell is highly crowded with proteins and other biomolecules. How proteins express their specific functions together with many off-target proteins in crowded cellular environments is largely unknown. Here, we investigate an inhibitor binding with c-Src kinase using atomistic molecular dynamics (MD) simulations in dilute as well as crowded protein solution. The populations of the inhibitor, 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP1), in bulk solution and on the surface of c-Src kinase are reduced as the concentration of crowder bovine serum albumins (BSAs) increases. This observation is consistent with the reduced PP1 inhibitor efficacy in experimental c-Src kinase assays in addition with BSAs. The crowded environment changes the major binding pathway of PP1 toward c-Src kinase compared to that in dilute solution. This change is explained based on the population shift mechanism of local conformations near the inhibitor binding site in c-Src kinase.

[Novel Tyrosine Phosphorylation Signals in the Nucleus and on Mitotic Spindle Fibers and Lysosomes Revealed by Strong Inhibition of Tyrosine Dephosphorylation]

Protein-tyrosine phosphorylation is one of the posttranslational modifications and plays critical roles in regulating a wide variety of cellular processes, such as cell proliferation, differentiation, adhesion, migration, survival, and apoptosis. Protein-tyrosine phosphorylation is reversibly regulated by protein-tyrosine kinases and protein-tyrosine phosphatases. Strong inhibition of protein-tyrosine phosphatase activities is required to undoubtedly detect tyrosine phosphorylation. Our extremely careful usage of Na₃VO₄, a potent protein-tyrosine phosphatase inhibitor, has revealed not only the different intracellular trafficking pathways of Src-family tyrosine kinase members but also novel tyrosine phosphorylation signals in the nucleus and on mitotic spindle fibers and lysosomes. Furthermore, despite that the first identified oncogene product v-Src is generally believed to induce transformation through continuous stimulation of proliferation signaling by its strong tyrosine kinase activity, v-Src-driven transformation was found to be caused not by continuous proliferation signaling but by v-Src tyrosine kinase activity-dependent stochastic genome alterations. Here, I summarize our findings regarding novel tyrosine phosphorylation signaling in a spatiotemporal sense and highlight the significance of the roles of tyrosine phosphorylation in transcriptional regulation inside the nucleus and chromosome dynamics.

Self-assembly of an anion receptor with metal-dependent kinase inhibition and potent in vitro anti-cancer properties

One topical area of supramolecular chemistry is the binding of anionic species but despite the importance of anions in diverse cellular processes and for cancer development, anion receptors or 'binders' have received little attention as potential anti-cancer therapeutics. Here we report self-assembling trimetallic cryptands (e.g. [L₂(Metal)₃]⁶⁺ where Metal = Cu²⁺, Zn²⁺ or Mn²⁺) which can encapsulate a range of anions and which show metal-dependent differences in chemical and biological reactivities. In cell studies, both [L₂Cu₃]⁶⁺ and [L₂Zn₃]⁶⁺ complexes are highly toxic to a range of human cancer cell lines and they show significant metal-dependent selective activity towards cancer cells compared to healthy, non-cancerous cells (by up to 2000-fold). The addition of different anions to the complexes (e.g. PO₄³-, SO₄²- or PhOPO₃²-) further alters activity and selectivity allowing the activity to be modulated via a self-assembly process. The activity is attributed to the ability to either bind or hydrolyse phosphate esters and mechanistic studies show differential and selective inhibition of multiple kinases by both [L₂Cu₃]⁶⁺ and [L₂Zn₃]⁶⁺ complexes but via different mechanisms.

The mechanisms of colorectal cancer cell mesenchymal-epithelial transition induced by hepatocyte exosome-derived miR-203a-3p

Background

Liver metastasis is the most common cause of death in patients with colorectal cancer (CRC). Phosphatase of regenerating liver-3 induces CRC metastasis by epithelial-to-mesenchymal transition, which promotes CRC cell liver metastasis. Mesenchymal-to-epithelial transition (MET), the opposite of epithelial-to-mesenchymal transition, has been proposed as a mechanism for the establishment of metastatic neoplasms. However, the molecular mechanism of MET remains unclear.

Methods

Using Immunohistochemistry, western blotting, invasion assays, real-time quantitative PCR, chromatin immunoprecipitation, luciferase reporter assays, human miRNA arrays, and xenograft mouse model, we determined the role of hepatocyte exosome-derived miR-203a-3p in CRC MET.

Results

In our study, we found that miR-203a-3p derived from hepatocyte exosomes increased colorectal cancer cells E-cadherin expression, inhibited Src expression, and reduced activity. In this way miR-203a-3p induced the decreased invasion rate of CRC cells.

Coclusion

MiR-203a-3p derived from hepatocyte exosomes plays an important role of CRC cells to colonize in liver.

The nonreceptor protein tyrosine kinase Src participates in every step of cancer-induced bone pain

Cancer-induced bone pain (CIBP) is a refractory form of pain that has a high incidence in advanced tumors. Src protein tyrosine kinase is mainly composed of six domains, with two states of automatic inhibition and activation. The modular domain allows Src to conveniently regulate by and communicate with a variety of proteins, directly or indirectly participate in each step of the CIBP process. Src is beneficial to the growth and proliferation of tumor cells, and it can promote the metastases of primary tumors to bone. In the microenvironment of bone metastasis, it mainly mediates bone resorption, activates related peripheral receptors to participate in the formation of pain signals, and may promote the generation of pathological sensory nerve fibers. In the process of pain signal transmission, it mainly mediates NMDAR and central glial cells to regulate pain signal intensity and central sensitization, but it is not limited to these two aspects. Both basic experimentation and clinical research have shown encouraging potential, providing new ideas and inspiration for the prevention and treatment of CIBP.

The tumor suppressor LATS2 reduces v-Src-induced membrane blebs in a kinase activity-independent manner

When cells with excess DNA, such as tetraploid cells, undergo cell division, it can contribute to cellular transformation via asymmetrical chromosome segregation-generated genetic diversity. Cell cycle progression of tetraploid cells is suppressed by large tumor suppressor 2 (LATS2) kinase-induced inhibitory phosphorylation of the transcriptional coactivator Yes-associated protein (YAP). We recently reported that the oncogene v-Src induces tetraploidy and promotes cell cycle progression of tetraploid cells by suppressing LATS2 activity. We explore here the mechanism by which v-Src suppresses LATS2 activity and the role of LATS2 in v-Src-expressing cells. LATS2 was directly phosphorylated by v-Src and the proto-oncogene c-Src, resulting in decreased LATS2 kinase activity. This kinase-deficient LATS2 accumulated in a YAP transcriptional activity-dependent manner, and knockdown of either LATS2 or the LATS2-binding partner moesin-ezrin-radixin-like protein (Merlin) accelerated v-Src-induced membrane bleb formation. Upon v-Src expression, the interaction of Merlin with LATS2 was increased possibly due to a decrease in Merlin phosphorylation at Ser518, the dephosphorylation of which is required for the open conformation of Merlin and interaction with LATS2. LATS2 was colocalized with Merlin at the plasma membrane in a manner that depends on the Merlin-binding region of LATS2. The bleb formation in v-Src-expressing and LATS2-knockdown cells was rescued by the reexpression of wild-type or kinase-dead LATS2 but not the LATS2 mutant lacking the Merlin-binding region. These results suggest that the kinase-deficient LATS2 plays a role with Merlin at the plasma membrane in the maintenance of cortical rigidity in v-Src-expressing cells, which may cause tumor suppression.

TRP Channels Interactome as a Novel Therapeutic Target in Breast Cancer

Breast cancer is one of the most frequent cancer types worldwide and the first cause of cancer-related deaths in women. Although significant therapeutic advances have been achieved with drugs such as tamoxifen and trastuzumab, breast cancer still caused 627,000 deaths in 2018. Since cancer is a multifactorial disease, it has become necessary to develop new molecular therapies that can target several relevant cellular processes at once. Ion channels are versatile regulators of several physiological- and pathophysiological-related mechanisms, including cancer-relevant processes such as tumor progression, apoptosis inhibition, proliferation, migration, invasion, and chemoresistance. Ion channels are the main regulators of cellular functions, conducting ions selectively through a pore-forming structure located in the plasma membrane, protein–protein interactions one of their main regulatory mechanisms. Among the different ion channel families, the Transient Receptor Potential (TRP) family stands out in the context of breast cancer since several members have been proposed as prognostic markers in this pathology. However, only a few approaches exist to block their specific activity during tumoral progress. In this article, we describe several TRP channels that have been involved in breast cancer progress with a particular focus on their binding partners that have also been described as drivers of breast cancer progression. Here, we propose disrupting these interactions as attractive and potential new therapeutic targets for treating this neoplastic disease.

Cell Plasticity and Prostate Cancer: The Role of Epithelial-Mesenchymal Transition in Tumor Progression, Invasion, Metastasis and Cancer Therapy Resistance

Simple Summary

Although epithelial-to-mesenchymal transition (EMT) is a well-known cellular process involved during normal embryogenesis and wound healing, it also has a dark side; it is a complex process that provides tumor cells with a more aggressive phenotype, facilitating tumor metastasis and even resistance to therapy. This review focuses on the key pathways of EMT in the pathogenesis of prostate cancer and the development of metastases and evasion of currently available treatments.

Abstract

Prostate cancer, the second most common malignancy in men, is characterized by high heterogeneity that poses several therapeutic challenges. Epithelial–mesenchymal transition (EMT) is a dynamic, reversible cellular process which is essential in normal embryonic morphogenesis and wound healing. However, the cellular changes that are induced by EMT suggest that it may also play a central role in tumor progression, invasion, metastasis, and resistance to current therapeutic options. These changes include enhanced motility and loss of cell–cell adhesion that form a more aggressive cellular phenotype. Moreover, the reverse process (MET) is a necessary element of the metastatic tumor process. It is highly probable that this cell plasticity reflects a hybrid state between epithelial and mesenchymal status. In this review, we describe the underlying key mechanisms of the EMT-induced phenotype modulation that contribute to prostate tumor aggressiveness and cancer therapy resistance, in an effort to provide a framework of this complex cellular process.

Pharmacological targeting of TNS3 with histone deacetylase inhibitor as a therapeutic strategy in esophageal squamous cell carcinoma

Histone acetylation which regulates about 2-10% of genes has been demonstrated to be involved in tumorigenesis of esophageal squamous cell carcinoma (ESCC). In this study, we investigated the treatment response of ESCC to selective histone deacetylase inhibitor (HDACi) LMK-235 and potential biomarker predicting the treatment sensitivity. We identified tensin-3 (TNS3) which was highly over-expressed in ESCC as one of the down-regulated genes in response to LMK-235 treatment. TNS3 was found positively correlated with the tumor malignancy and poor prognosis in the patients. Silencing TNS3 significantly inhibited ESCC cell proliferation both in vitro and in vivo, sensitizing the treatment response to LMK-235. Our findings provide an insight into understanding the oncogenic role of TNS3 in ESCC and its clinical application for HDAC targeted therapy of ESCC.

Characterization of unique functionalities in c-Src domains required for osteoclast podosome belt formation

Deletion of c-Src, a ubiquitously expressed tyrosine kinase, results in osteoclast dysfunction and osteopetrosis, in which bones harden into "stone." In contrast, deletion of the genes encoding other members of the Src family kinase (SFK) fails to produce an osteopetrotic phenotype. This suggests that c-Src performs a unique function in the osteoclast that cannot be compensated for by other SFKs. We aimed to identify the molecular basis of this unique role in osteoclasts and bone resorption. We found that c-Src, Lyn, and Fyn were the most highly expressed SFKs in WT osteoclasts, whereas Hck, Lck, Blk, and Fgr displayed low levels of expression. Formation of the podosome belt, clusters of unique actin assemblies, was disrupted in src^-/- osteoclasts; introduction of constitutively activated SFKs revealed that only c-Src and Fyn could restore this process. To identify the key structural domains responsible, we constructed chimeric Src-Hck and Src-Lyn constructs in which the unique, SH3, SH2, or catalytic domains had been swapped. We found that the Src unique, SH3, and kinase domains were each crucial to establish Src functionality. The SH2 domain could however be substituted with Lyn or Hck SH2 domains. Furthermore, we demonstrate that c-Src's functionality is, in part, derived from an SH3-proximal proline-rich domain interaction with c-Cbl, leading to phosphorylation of c-Cbl Tyr700. These data help clarify Src's unique functionality in the organization of the cytoskeleton in osteoclasts, required for efficient bone resorption and explain why c-Src cannot be replaced, in osteoclasts, by other SFKs.

Cyclic Peptides as Protein Kinase Inhibitors: Structure-Activity Relationship and Molecular Modeling

Under-expression or overexpression of protein kinases has been shown to be associated with unregulated cell signal transduction in cancer cells. Therefore, there is major interest in designing protein kinase inhibitors as anticancer agents. We have previously reported [WR]₅, a peptide containing alternative arginine (R) and tryptophan (W) residues as a non-competitive c-Src tyrosine kinase inhibitor. A number of larger cyclic peptides containing alternative hydrophobic and positively charged residues [WR]_x (x = 6-9) and hybrid cyclic-linear peptides, [R₆K]W₆ and [R₅K]W₇, containing R and W residues were evaluated for their protein kinase inhibitory potency. Among all the peptides, cyclic peptide [WR]₉ was found to be the most potent tyrosine kinase inhibitor. [WR]₉ showed higher inhibitory activity (IC₅₀ = 0.21 μM) than [WR]₅, [WR]₆, [WR]₇, and [WR]₈ with IC₅₀ values of 0.81, 0.57, 0.35, and 0.33 μM, respectively, against c-Src kinase as determined by a radioactive assay using [γ-³³P]ATP. Consistent with the result above, [WR]₉ inhibited other protein kinases such as Abl kinase activity with an IC₅₀ value of 0.35 μM, showing 2.2-fold higher inhibition than [WR]₅ (IC₅₀ = 0.79 μM). [WR]₉ also inhibited PKCa kinase activity with an IC₅₀ value of 2.86 μM, approximately threefold higher inhibition than [WR]₅ (IC₅₀ = 8.52 μM). A similar pattern was observed against Braf, c-Src, Cdk2/cyclin A1, and Lck. [WR]₉ exhibited IC₅₀ values of <0.25 μM against Akt1, Alk, and Btk. These data suggest that [WR]₉ is consistently more potent than other cyclic peptides with a smaller ring size and hybrid cyclic-linear peptides [R₆K]W₆ and [R₅K]W₇ against selected protein kinases. Thus, the presence of R and W residues in the ring, ring size, and the number of amino acids in the structure of the cyclic peptide were found to be critical in protein kinase inhibitory potency. We identified three putative binding pockets through automated blind docking of cyclic peptides [WR]_(5-9). The most populated pocket is located between the SH2, SH3, and N-lobe domains on the opposite side of the ATP binding site. The second putative pocket is formed by the same domains and located on the ATP binding site side of the protein. Finally, a third pocket was identified between the SH2 and SH3 domains. These results are consistent with the non-competitive nature of the inhibition displayed by these molecules. Molecular dynamics simulations of the protein-peptide complexes indicate that the presence of either [WR]₅ or [WR]₉ affects the plasticity of the protein and in particular the volume of the ATP binding site pocket in different ways. These results suggest that the second pocket is most likely the site where these peptides bind and offer a plausible rationale for the increased affinity of [WR]₉.

Structure-Activity Study of Nitazoxanide Derivatives as Novel STAT3 Pathway Inhibitors

We identified nitazoxanide (NTZ) as a moderate STAT3 pathway inhibitor through immunoblot analysis and a cell-based IL-6/JAK/STAT3 pathway activation assay. A series of thiazolide derivatives were designed and synthesized to further validate the thiazolide scaffold as STAT3 inhibitors. Eight out of 25 derivatives displayed potencies greater than that of NTZ, and their STAT3 pathway inhibitory activities were found to be significantly correlated with their antiproliferative activities in HeLa cells. Derivatives 15 and 24 were observed to be more potent than the positive control WP1066, which is under phase I clinical trials. Compared with NTZ, 15 also exhibited much improved in vivo pharmacokinetic parameters in rats and efficacies against proliferations in multiple cancer cell lines, indicating a broad-spectrum effect of these thiazolides as antitumor agents targeted on STAT3.

Current Views on the Interplay between Tyrosine Kinases and Phosphatases in Chronic Myeloid Leukemia

Simple Summary

The chromosomal alteration t(9;22) generating the BCR-ABL1 fusion protein represents the principal feature that distinguishes some types of leukemia. An increasing number of articles have focused the attention on the relevance of protein phosphatases and their potential role in the control of BCR-ABL1-dependent or -independent signaling in different areas related to the biology of chronic myeloid leukemia. Herein, we discuss how tyrosine and serine/threonine protein phosphatases may interact with protein kinases, in order to regulate proliferative signal cascades, quiescence and self-renewals on leukemic stem cells, and drug-resistance, indicating how BCR-ABL1 can (directly or indirectly) affect these critical cells behaviors. We provide an updated review of the literature on the function of protein phosphatases and their regulation mechanism in chronic myeloid leukemia.

Abstract

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by BCR-ABL1 oncogene expression. This dysregulated protein-tyrosine kinase (PTK) is known as the principal driver of the disease and is targeted by tyrosine kinase inhibitors (TKIs). Extensive documentation has elucidated how the transformation of malignant cells is characterized by multiple genetic/epigenetic changes leading to the loss of tumor-suppressor genes function or proto-oncogenes expression. The impairment of adequate levels of substrates phosphorylation, thus affecting the balance PTKs and protein phosphatases (PPs), represents a well-established cellular mechanism to escape from self-limiting signals. In this review, we focus our attention on the characterization of and interactions between PTKs and PPs, emphasizing their biological roles in disease expansion, the regulation of LSCs and TKI resistance. We decided to separate those PPs that have been validated in primary cell models or leukemia mouse models from those whose studies have been performed only in cell lines (and, thus, require validation), as there may be differences in the manner that the associated pathways are modified under these two conditions. This review summarizes the roles of diverse PPs, with hope that better knowledge of the interplay among phosphatases and kinases will eventually result in a better understanding of this disease and contribute to its eradication.

Can Src protein tyrosine kinase inhibitors be combined with opioid analgesics? Src and opioid-induced tolerance, hyperalgesia and addiction

The clinical application of opioids may be accompanied by a series of adverse consequences, such as opioid tolerance, opioid-induced hyperalgesia, opioid dependence or addiction. In view of this issue, clinicians are faced with the dilemma of treating various types of pain with or without opioids. In this review, we discuss that Src protein tyrosine kinase plays an important role in these adverse consequences, and Src inhibitors can solve these problems well. Therefore, Src inhibitors have the potential to be used in combination with opioids to achieve synergy. How to combine them together to maximize the analgesic effect while avoiding unnecessary trouble provides a topic for follow-up research.

Novel Majeed Syndrome-Causing LPIN2 Mutations Link Bone Inflammation to Inflammatory M2 Macrophages and Accelerated Osteoclastogenesis

Objective

To identify novel heterozygous LPIN2 mutations in a patient with Majeed syndrome and characterize the pathomechanisms that lead to the development of sterile osteomyelitis.

Methods

Targeted genetic analysis and functional studies assessing monocyte responses, macrophage differentiation, and osteoclastogenesis were conducted to compare the pathogenesis of Majeed syndrome to interleukin‐1 (IL‐1)–mediated diseases including neonatal‐onset multisystem inflammatory disease (NOMID) and deficiency of the IL‐1 receptor antagonist (DIRA).

Results

A 4‐year‐old girl of mixed ethnic background presented with sterile osteomyelitis and elevated acute‐phase reactants. She had a 17.8‐kb deletion on the maternal LPIN2 allele and a splice site mutation, p.R517H, that variably spliced out exons 10 and 11 on the paternal LPIN2 allele. The patient achieved long‐lasting remission receiving IL‐1 blockade with canakinumab. Compared to controls, monocytes and monocyte‐derived M1‐like macrophages from the patient with Majeed syndrome and those with NOMID or DIRA had elevated caspase 1 activity and IL‐1β secretion. In contrast, lipopolysaccharide‐stimulated, monocyte‐derived, M2‐like macrophages from the patient with Majeed syndrome released higher levels of osteoclastogenic mediators (IL‐8, IL‐6, tumor necrosis factor, CCL2, macrophage inflammatory protein 1α/β, CXCL8, and CXCL1) compared to NOMID patients and healthy controls. Accelerated osteoclastogenesis in the patient with Majeed syndrome was associated with higher NFATc1 levels, enhanced JNK/MAPK, and reduced Src kinase activation, and partially responded to JNK inhibition and IL‐1 (but not IL‐6) blockade.

Conclusion

We report 2 novel compound heterozygous disease‐causing mutations in LPIN2 in an American patient with Majeed syndrome. LPIN2 deficiency drives differentiation of proinflammatory M2‐like macrophages and enhances intrinsic osteoclastogenesis. This provides a model for the pathogenesis of sterile osteomyelitis which differentiates Majeed syndrome from other IL‐1–mediated autoinflammatory diseases.

Toll receptors remodel epithelia by directing planar-polarized Src and PI3K activity

Toll-like receptors are essential for animal development and survival, with conserved roles in innate immunity, tissue patterning, and cell behavior. The mechanisms by which Toll receptors signal to the nucleus are well characterized, but how Toll receptors generate rapid, localized signals at the cell membrane to produce acute changes in cell polarity and behavior is not known. We show that Drosophila Toll receptors direct epithelial convergent extension by inducing planar-polarized patterns of Src and PI3-kinase (PI3K) activity. Toll receptors target Src activity to specific sites at the membrane, and Src recruits PI3K to the Toll-2 complex through tyrosine phosphorylation of the Toll-2 cytoplasmic domain. Reducing Src or PI3K activity disrupts planar-polarized myosin assembly, cell intercalation, and convergent extension, whereas constitutive Src activity promotes ectopic PI3K and myosin cortical localization. These results demonstrate that Toll receptors direct cell polarity and behavior by locally mobilizing Src and PI3K activity.

Connexin43 peptide, TAT-Cx43266-283, selectively targets glioma cells, impairs malignant growth, and enhances survival in mouse models in vivo

Background

Malignant gliomas are the most frequent primary brain tumors and remain among the most incurable cancers. Although the role of the gap junction protein, connexin43 (Cx43), has been deeply investigated in malignant gliomas, no compounds have been reported with the ability to recapitulate the tumor suppressor properties of this protein in in vivo glioma models.

Methods

TAT-Cx43_266–283 a cell-penetrating peptide which mimics the effect of Cx43 on c-Src inhibition, was studied in orthotopic immunocompetent and immunosuppressed models of glioma. The effects of this peptide in brain cells were also analyzed.

Results

While glioma stem cell malignant features were strongly affected by TAT-Cx43_266–283, these properties were not significantly modified in neurons and astrocytes. Intraperitoneally administered TAT-Cx43_266–283 decreased the invasion of intracranial tumors generated by GL261 mouse glioma cells in immunocompetent mice. When human glioma stem cells were intracranially injected with TAT-Cx43_266–283 into immunodeficient mice, there was reduced expression of the stemness markers nestin and Sox2 in human glioma cells at 7 days post-implantation. Consistent with the role of Sox2 as a transcription factor required for tumorigenicity, TAT-Cx43_266–283 reduced the number and stemness of human glioma cells at 30 days post-implantation. Furthermore, TAT-Cx43_266–283 enhanced the survival of immunocompetent mice bearing gliomas derived from murine glioma stem cells.

Conclusion

TAT-Cx43_266–283 reduces the growth, invasion, and progression of malignant gliomas and enhances the survival of glioma-bearing mice without exerting toxicity in endogenous brain cells, which suggests that this peptide could be considered as a new clinical therapy for high-grade gliomas.

EGFR-dependent tyrosine phosphorylation of integrin β4 is not required for downstream signaling events in cancer cell lines

In epithelial cancers, the epidermal growth factor receptor (EGFR) and integrin α6β4 are frequently overexpressed and found to synergistically activate intracellular signaling pathways that promote cell proliferation and migration. In cancer cells, the β4 subunit is phosphorylated at tyrosine residues not normally recognized as kinase substrates; however, the function of these phosphotyrosine residues in cancer cells is a subject of much debate. In EGFR-overexpressing carcinoma cells, we found that the Src family kinase (SFK) inhibitor PP2 reduces β4 tyrosine phosphorylation following the activation of EGFR. However, siRNA mediated knockdown of the SFKs Src, Fyn, Yes and Lyn, individually or in combination, did not affect the EGF-induced phosphorylation of β4. Using phospho-peptide affinity chromatography and mass spectrometry, we found that PLCγ1 binds β4 at the phosphorylated residues Y1422/Y1440, but were unable to verify this interaction in A431 carcinoma cells that overexpress the EGFR. Furthermore, using A431 cells devoid of β4 or reconstituted with phenylalanine specific mutants of β4, the activation of several downstream signaling pathways, including PLCγ/PKC, MAPK and PI3K/Akt, were not substantially affected. We conclude that tyrosine-phosphorylated β4 does not enhance EGFR-mediated signaling in EGFR-overexpressing cells, despite the fact that this integrin subunit is highly tyrosine phosphorylated in these cells.

c-Src Promotes Tumorigenesis and Tumor Progression by Activating PFKFB3

Reprogramming of glucose metabolism is a key event in tumorigenesis and progression. Here, we show that active c-Src stimulates glycolysis by phosphorylating (Tyr194) and activating PFKFB3, a key enzyme that boosts glycolysis by producing fructose-2,6-bisphosphate and activating PFK1. Increased glycolysis intermediates replenish non-oxidative pentose phosphate pathway (PPP) and serine pathway for biosynthesis of cancer cells. PFKFB3 knockout (KO) cells and their counterpart reconstituted with PFKFB3-Y194F show comparably impaired abilities for proliferation, migration, and xenograft formation. Furthermore, PFKFB3-Y194F knockin mice show impaired glycolysis and, mating of these mice with APC^min/+ mice attenuates spontaneous colon cancer formation in APC^min/+ mice. In summary, we identify a specific mechanism by which c-Src mediates glucose metabolism to meet cancer cells' requirements for maximal biosynthesis and proliferation. The PFKFB3-Tyr194 phosphorylation level highly correlates with c-Src activity in clinical tumor samples, indicating its potential as an evaluation for tumor prognosis.

Recent Progress in the Development of Quinoline Derivatives for the Exploitation of Anti-Cancer Agents

BACKGROUND

Along with the progress in medicine and therapies, the exploitation of anti-cancer agents focused more on the vital signaling pathways and key biological macromolecules. With rational design and advanced synthesis, quinoline derivatives have been utilized frequently in medicinal chemistry, especially in developing anti-cancer drugs or candidates.

METHODS

Using DOI searching, articles published before 2020 all over the world have been reviewed as comprehensively as possible.

RESULTS

In this review, we selected the representative quinoline derivate drugs in market or clinical trials, classified them into five major categories with detailed targets according to their main mechanisms, discussed the relationship within the same mechanism, and generated a summative discussion with prospective expectations. For each mechanism, the introduction of the target was presented, with the typical examples of quinoline derivate drugs.

CONCLUSION

This review has highlighted the quinoline drugs or candidates, suited them into corresponding targets in their pathways, summarized and discussed. We hope that this review may help the researchers who are interested in discovering quinoline derivate anti-cancer agents obtain considerable understanding of this specific topic. Through the flourishing period and the vigorous strategies in clinical trials, quinoline drugs would be potential but facing new challenges in the future.

Translocation of HSP47 and generation of mitochondrial reactive oxygen species in human neuroblastoma SK-N-SH cells following electron and X-ray irradiation

Generation of mitochondrial reactive oxygen species (ROS), lipid peroxidation, 4-hydroxy-2-nonenal, and heat-shock protein (HSP) 47 after electron and X-ray irradiations were detected in the human neuroblastoma cell line SK-N-SH. After 10 Gy electron irradiation and 15 Gy X-ray irradiation, mitochondrial ROS production and lipid peroxidation were significantly increased. Additionally, we observed a significant increase in the levels of HSP47 after 3 and 10 Gy electron irradiation as well as 15 Gy X-ray irradiation. Furthermore, myristoylation and farnesylation were increased after 10 Gy electron and 15 Gy X-ray irradiations. We found that the level of HSP47 increased in the mitochondria after 10 Gy electron and 15 Gy X-ray irradiations. HSP47 coexisted with myristoylation and farnesylation. Furthermore, HSP47 overexpression increased mitochondrial ROS production. These results suggest that HSP47 plays an important role in mitochondria and induces mitochondrial ROS production in SK-N-SH cells.