Non-receptor protein tyrosine kinases signaling pathways in normal and cancer cells

A reanalysis and integration of transcriptomics and proteomics datasets unveil novel drug targets for Mekong schistosomiasis

Schistosomiasis, caused by Schistosoma trematodes, is a significant global health concern, particularly affecting millions in Africa and Southeast Asia. Despite efforts to combat it, the rise of praziquantel (PZQ) resistance underscores the need for new treatment options. Protein kinases (PKs) are vital in cellular signaling and offer potential as drug targets. This study focused on focal adhesion kinase (FAK) as a candidate for anti-schistosomal therapy. Transcriptomic and proteomic analyses of adult S. mekongi worms identified FAK as a promising target due to its upregulation and essential role in cellular processes. Molecular docking simulations assessed the binding energy of FAK inhibitors to Schistosoma FAK versus human FAK. FAK inhibitor 14 and PF-03814735 exhibited strong binding to Schistosoma FAK with minimal binding for human FAK. In vitro assays confirmed significant anti-parasitic activity against S. mekongi, S. mansoni, and S. japonicum, comparable to PZQ, with low toxicity in human cells, indicating potential safety. These findings highlight FAK as a promising target for novel anti-schistosomal therapies. However, further research, including in vivo studies, is necessary to validate efficacy and safety before clinical use. This study offers a hopeful strategy to combat schistosomiasis and reduce its global impact.

phuEGO: A Network-Based Method to Reconstruct Active Signaling Pathways From Phosphoproteomics Datasets

Signaling networks are critical for virtually all cell functions. Our current knowledge of cell signaling has been summarized in signaling pathway databases, which, while useful, are highly biased toward well-studied processes, and do not capture context specific network wiring or pathway cross-talk. Mass spectrometry-based phosphoproteomics data can provide a more unbiased view of active cell signaling processes in a given context, however, it suffers from low signal-to-noise ratio and poor reproducibility across experiments. While progress in methods to extract active signaling signatures from such data has been made, there are still limitations with respect to balancing bias and interpretability. Here we present phuEGO, which combines up-to-three-layer network propagation with ego network decomposition to provide small networks comprising active functional signaling modules. PhuEGO boosts the signal-to-noise ratio from global phosphoproteomics datasets, enriches the resulting networks for functional phosphosites and allows the improved comparison and integration across datasets. We applied phuEGO to five phosphoproteomics data sets from cell lines collected upon infection with SARS CoV2. PhuEGO was better able to identify common active functions across datasets and to point to a subnetwork enriched for known COVID-19 targets. Overall, phuEGO provides a flexible tool to the community for the improved functional interpretation of global phosphoproteomics datasets.

Taking Me away: the function of phosphorylation on histone lysine demethylases

Histone lysine demethylases (KDMs) regulate eukaryotic gene transcription by catalysing the removal of methyl groups from histone proteins. These enzymes are intricately regulated by the kinase signalling system in response to internal and external stimuli. Here, we review the mechanisms by which kinase-mediated phosphorylation influence human histone KDM function. These include the changing of histone KDM subcellular localisation or chromatin binding, the altering of protein half-life, changes to histone KDM complex formation that result in histone demethylation, non-histone demethylation or demethylase-independent effects, and effects on histone KDM complex dissociation. We also explore the structural context of phospho-sites on histone KDMs and evaluate how this relates to function.

Integrating network pharmacology, molecular docking and simulation approaches with machine learning reveals the multi-target pharmacological mechanism of Berberis integerrima against diabetic nephropathy

Diabetic nephropathy (DN) is one of the most feared complications of diabetes and key cause of end-stage renal disease (ESRD). Berberis integerrima has been widely used to treat diabetic complications, but exact molecular mechanism is yet to be discovered. Data on active ingredients of B. integerrima and target genes of both diabetic nephropathy and B.integerrima were obtained from public databases. Common results between B. integerrima and DN targets were used to create protein-protein interaction (PPI) network using STRING database and exported to Cytoscape software for the selection of hub genes based on degree of connectivity. Future, PPI network between constituents and overlapping targets was created using Cytoscape to investigate the network pharmacological effects of B. integerrima on DN. KEGG pathway analysis of core genes exposed their involvement in excess glucose-activated signaling pathway. Then, expression of core genes was validated through machine learning classifiers. Finally, PyRx and AMBER18 software was used for molecular docking and simulation. We found that Armepavine, Berberine, Glaucine, Magnoflorine, Reticuline, Quercetin inhibits the growth of diabetic nephropathy by affecting ICAM1, PRKCB, IKBKB, KDR, ALOX5, VCAM1, SYK, TBXA2R, LCK, and F3 genes. Machine learning revealed SYK and PRKCB as potential genes that could use as diagnostic biomarkers against DN. Furthermore, docking and simulation analysis showed the binding affinity and stability of the active compound with target genes. Our study revealed that B. integerrima has preventive effect on DN by acting on glucose-activated signaling pathways. However, experimental studies are needed to reveal biosafety profiles of B. integerrima in DN.Communicated by Ramaswamy H. Sarma.

Integrating Clinical Cancer and PTM Proteomics Data Identifies a Mechanism of ACK1 Kinase Activation

Beyond the most common oncogenes activated by mutation (mut-drivers), there likely exists a variety of low-frequency mut-drivers, each of which is a possible frontier for targeted therapy. To identify new and understudied mut-drivers, we developed a machine learning (ML) model that integrates curated clinical cancer data and posttranslational modification (PTM) proteomics databases. We applied the approach to 62,746 patient cancers spanning 84 cancer types and predicted 3,964 oncogenic mutations across 1,148 genes, many of which disrupt PTMs of known and unknown function. The list of putative mut-drivers includes established drivers and others with poorly understood roles in cancer. This ML model is available as a web application. As a case study, we focused the approach on nonreceptor tyrosine kinases (NRTK) and found a recurrent mutation in activated CDC42 kinase-1 (ACK1) that disrupts the Mig6 homology region (MHR) and ubiquitin-association (UBA) domains on the ACK1 C-terminus. By studying these domains in cultured cells, we found that disruption of the MHR domain helps activate the kinase while disruption of the UBA increases kinase stability by blocking its lysosomal degradation. This ACK1 mutation is analogous to lymphoma-associated mutations in its sister kinase, TNK1, which also disrupt a C-terminal inhibitory motif and UBA domain. This study establishes a mut-driver discovery tool for the research community and identifies a mechanism of ACK1 hyperactivation shared among ACK family kinases.

IMPLICATIONS

This research identifies a potentially targetable activating mutation in ACK1 and other possible oncogenic mutations, including PTM-disrupting mutations, for further study.

CD133-Dependent Activation of Phosphoinositide 3-Kinase /AKT/Mammalian Target of Rapamycin Signaling in Melanoma Progression and Drug Resistance

Melanoma frequently harbors genetic alterations in key molecules leading to the aberrant activation of PI3K and its downstream pathways. Although the role of PI3K/AKT/mTOR in melanoma progression and drug resistance is well documented, targeting the PI3K/AKT/mTOR pathway showed less efficiency in clinical trials than might have been expected, since the suppression of the PI3K/mTOR signaling pathway-induced feedback loops is mostly associated with the activation of compensatory pathways such as MAPK/MEK/ERK. Consequently, the development of intrinsic and acquired resistance can occur. As a solid tumor, melanoma is notorious for its heterogeneity. This can be expressed in the form of genetically divergent subpopulations including a small fraction of cancer stem-like cells (CSCs) and non-cancer stem cells (non-CSCs) that make the most of the tumor mass. Like other CSCs, melanoma stem-like cells (MSCs) are characterized by their unique cell surface proteins/stemness markers and aberrant signaling pathways. In addition to its function as a robust marker for stemness properties, CD133 is crucial for the maintenance of stemness properties and drug resistance. Herein, the role of CD133-dependent activation of PI3K/mTOR in the regulation of melanoma progression, drug resistance, and recurrence is reviewed.

Oxidative versus Reductive Stress in Breast Cancer Development and Cellular Mechanism of Alleviation: A Current Perspective with Anti-breast Cancer Drug Resistance

Redox homeostasis is essential for keeping our bodies healthy, but it also helps breast cancer cells grow, stay alive, and resist treatment. Changes in the redox balance and problems with redox signaling can make breast cancer cells grow and spread and make them resistant to chemotherapy and radiation therapy. Reactive oxygen species/reactive nitrogen species (ROS/RNS) generation and the oxidant defense system are out of equilibrium, which causes oxidative stress. Many studies have shown that oxidative stress can affect the start and spread of cancer by interfering with redox (reduction-oxidation) signaling and damaging molecules. The oxidation of invariant cysteine residues in FNIP1 is reversed by reductive stress, which is brought on by protracted antioxidant signaling or mitochondrial inactivity. This permits CUL2FEM1B to recognize its intended target. After the proteasome breaks down FNIP1, mitochondrial function is restored to keep redox balance and cell integrity. Reductive stress is caused by unchecked amplification of antioxidant signaling, and changes in metabolic pathways are a big part of breast tumors' growth. Also, redox reactions make pathways like PI3K, PKC, and protein kinases of the MAPK cascade work better. Kinases and phosphatases control the phosphorylation status of transcription factors like APE1/Ref-1, HIF-1, AP-1, Nrf2, NF-B, p53, FOXO, STAT, and - catenin. Also, how well anti-breast cancer drugs, especially those that cause cytotoxicity by making ROS, treat patients depends on how well the elements that support a cell's redox environment work together. Even though chemotherapy aims to kill cancer cells, which it does by making ROS, this can lead to drug resistance in the long run. The development of novel therapeutic approaches for treating breast cancer will be facilitated by a better understanding of the reductive stress and metabolic pathways in tumor microenvironments.

Abnormal phosphorylation of protein tyrosine in neurodegenerative diseases

Neurodegenerative diseases, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and multiple sclerosis, are chronic disorders of the CNS that are characterized by progressive neuronal dysfunction. These diseases have diverse clinical and pathological features and their pathogenetic mechanisms are not yet fully understood. Currently, widely accepted hypotheses include the accumulation of misfolded proteins, oxidative stress from reactive oxygen species, mitochondrial dysfunction, DNA damage, neurotrophin dysfunction, and neuroinflammatory processes. In the CNS of patients with neurodegenerative diseases, a variety of abnormally phosphorylated proteins play important roles in pathological processes such as neuroinflammation and intracellular accumulation of β-amyloid plaques and tau. In recent years, the roles of abnormal tyrosine phosphorylation of intracellular signaling molecules regulated by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) in neurodegenerative diseases have attracted increasing attention. Here, we summarize the roles of signaling pathways related to protein tyrosine phosphorylation in the pathogenesis of neurodegenerative diseases and the progress of therapeutic studies targeting PTKs and PTPs that provide theoretical support for future studies on therapeutic strategies for these devastating and important neurodegenerative diseases.

Design and synthesis of novel hexahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivatives as potential anticancer agents with antiangiogenic activity via VEGFR-2 inhibition, and down-regulation of PI3K/AKT/mTOR signaling pathway

New thieno[2,3-d]pyrimidine derivatives were designed and synthesized. The National Cancer Institute (NCI) evaluated the synthesized novel compounds against a panel of 60 tumor cell lines for their antiproliferative activity. Compounds 6b, 6f, and 6g showed potent anticancer activity at 10 µM dose, with mean GI of 20.86%, 76.41%, and 31.49%, respectively. Compound 6f was selected for five-dose concentrations evaluation. Compound 6f scored a submicromolar range of GI50 values against 10 cancer cell lines, indicating broad-spectrum and potent antiproliferative activity. Compound 6f TGI values were recorded in the cytostatic range of 4.02-95.1 µM. In comparison to sorafenib, the tested compounds 6b, 6f, and 6g inhibited VEGFR-2 with IC50 values of 0.290 ± 0.032, 0.066 ± 0.004, and 0.16 ± 0.006 µM, correspondingly. Compound 6f significantly reduced the total VEGFR-2 expression and its phosphorylation. Additionally, 6f reduced the phosphorylation of PI3K, Akt, and mTOR pathway proteins. Moreover, the migratory potential of HUVECs was significantly reduced, after 72 h of treatment with compound 6f, resulting in disrupted wound healing patterns which verified the angiogenesis suppression properties of compound 6f. Compound 6f increased the total apoptosis percentage by 21.27-fold compared to sorafenib, which caused a 24.11-fold increase in the total apoptosis percentage. This apoptotic activity was accompanied by a 7.81-fold increase in the level of apoptotic caspase-3. Furthermore, the cell cycle analysis revealed that the target derivative 6f reduced cellular proliferation and induced an arrest in HCT-15 colon cancer cell cycle at the S phase. Molecular modeling was used to determine the binding profile and affinity of derivative 6f toward the VEGFR-2 active site.

Therapeutic Potential of Protein Tyrosine Kinase 6 in Colorectal Cancer

PTK6, a non-receptor tyrosine kinase, modulates the pathogenesis of breast and prostate cancers and is recognized as a biomarker of breast cancer prognosis. There are over 30 known substrates of PTK6, including signal transducers, transcription factors, and RNA-binding proteins. Many of these substrates are known drivers of other cancer types, such as colorectal cancer. Colon and rectal tumors also express higher levels of PTK6 than the normal intestine suggesting a potential role in tumorigenesis. However, the importance of PTK6 in colorectal cancer remains unclear. PTK6 inhibitors such as XMU-MP-2 and Tilfrinib have demonstrated potency and selectivity in breast cancer cells when used in combination with chemotherapy, indicating the potential for PTK6 targeted therapy in cancer. However, most of these inhibitors are yet to be tested in other cancer types. Here, we discuss the current understanding of the function of PTK6 in normal intestinal cells compared with colorectal cancer cells. We review existing PTK6 targeting therapeutics and explore the possibility of PTK6 inhibitory therapy for colorectal cancer.

Tyrosine kinase inhibitors and atherosclerosis: A close but complicated relationship

Targeted cancer therapies have revolutionized the treatment of the disease in the past decade. The tyrosine kinase inhibitor (TKI) class of drugs is a widely used option for treating various cancers. Despite numerous advances, clinical and experimental studies have demonstrated the atherosclerosis-inducing properties of these drugs that can cause adverse cardiovascular events. TKIs also have an atherosclerosis-preventing role in patients with cancer through different mechanisms under various conditions, suggesting that specific drugs play different roles in atherosclerosis regulation. Given these contradictory properties, this review summarizes the outcomes of previously performed clinical and basic experiments and shows how the targeted effects of novel TKIs affect atherosclerosis. Future collaborative efforts are warranted to enhance our understanding of the association between TKIs and atherosclerosis.

Design, Synthesis and Antitumor Activity of FAK/PLK1 Dual Inhibitors with Quinazolinone as the Skeleton

Febrifugine is a kind of quinazolinone compound with high biological activity from a Chinese herb called Chang Shan (Dichroa febrifuga). Febrifugine and its derivatives possess extensive biological activities, some of which exhibited anti-tumor activities as FAK inhibitors. However, they are not very effective at inhibiting tumor metastasis, perhaps because tumors gain energy through compensatory activation of other signaling pathways that promote cell migration and invasion. Therefore, seventeen novel febrifugine derivatives with quinazolinone skeleton were designed, synthesized and acted as potential FAK/PLK1 dual inhibitors. These compounds were determined by ¹ H-NMR, ¹³ C-NMR and MS. Most of the compounds exhibited good inhibitory activity against cancer cell lines by computer-assisted screening, antitumor activity test and FAK/PLK1 inhibitory activity test, wherein compound 3b was screened as a high-efficiency lead compound.

Insights into Lipid-Based Delivery Nanosystems of Protein-Tyrosine Kinase Inhibitors for Cancer Therapy

According to the WHO, cancer caused almost 10 million deaths worldwide in 2020, i.e., almost one in six deaths. Among the most common are breast, lung, colon and rectal and prostate cancers. Although the diagnosis is more perfect and spectrum of available drugs is large, there is a clear trend of an increase in cancer that ends fatally. A major advance in treatment was the introduction of gentler antineoplastics for targeted therapy-tyrosine kinase inhibitors (TKIs). Although they have undoubtedly revolutionized oncology and hematology, they have significant side effects and limited efficacy. In addition to the design of new TKIs with improved pharmacokinetic and safety profiles, and being more resistant to the development of drug resistance, high expectations are placed on the reformulation of TKIs into various drug delivery lipid-based nanosystems. This review provides an insight into the history of chemotherapy, a brief overview of the development of TKIs for the treatment of cancer and their mechanism of action and summarizes the results of the applications of self-nanoemulsifying drug delivery systems, nanoemulsions, liposomes, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles and nanostructured lipid carriers used as drug delivery systems of TKIs obtained in vitro and in vivo.

Trial Watch: combination of tyrosine kinase inhibitors (TKIs) and immunotherapy

The past decades witnessed the clinical employment of targeted therapies including but not limited to tyrosine kinase inhibitors (TKIs) that restrain a broad variety of pro-tumorigenic signals. TKIs can be categorized into (i) agents that directly target cancer cells, (ii) normalize angiogenesis or (iii) affect cells of the hematologic lineage. However, a clear distinction of TKIs based on this definition is limited by the fact that many TKIs designed to inhibit cancer cells have also effects on immune cells that are being discovered. Additionally, TKIs originally designed to target hematological cancers exhibit bioactivities on healthy cells of the same hematological lineage. TKIs have been described to improve immune recognition and cancer immunosurveillance, providing the scientific basis to combine TKIs with immunotherapy. Indeed, combination of TKIs with immunotherapy showed synergistic effects in preclinical models and clinical trials and some combinations of TKIs normalizing angiogenesis with immune checkpoint blocking antibodies have already been approved by the FDA for cancer therapy. However, the identification of appropriate drug combinations as well as optimal dosing and scheduling needs to be improved in order to obtain tangible progress in cancer care. This Trial Watch summarizes active clinical trials combining TKIs with various immunotherapeutic strategies to treat cancer patients.

Investigation of molecular mechanism leading to gefitinib and osimertinib resistance against EGFR tyrosine kinase: molecular dynamics and binding free energy calculation

Tyrosine kinase (TK) is an important protein responsible for phosphorylation of variety of proteins that helps in signal transduction process in transferring signal to regulate various physiological and biochemical processes. Drugs inhibiting signal transduction pathways can be a very rational approach to inhibit cellular physiological and biochemical process. Tyrosine kinase inhibitors are a wide family of drugs that have been used successfully in cancer chemotherapy. Certain mutations around the catalytic cleft may cause conformational changes at binding site and leads to decrease in inhibitor sensitivity to TK mutants. EGFR^T790M mutation is the first recognized acquired resistance after tyrosine kinase inhibitor therapy that leads to resistant to first generation TKI in about 50% of non-small cell lung carcinoma patients. Third generation EGFR-TKIs bind irreversibly to the C797, which is present in the ATP-binding pocket. The present work provides a molecular mechanism for understanding the Gefitinib and Osimertinib sensitivities with the EGFR^WILD, EGFR^L858R, EGFR^T790M, EGFR^T790M+C797S mutants using molecular modelling techniques. Changes in response against Gefitinib and Osimertinib were observed with the change of amino acids at the tyrosine kinase domain of EGFR^WILD and its mutants (EGFR^L858R, EGFR^T790M, EGFR^T790M+C797S). RMSD, RMSF and binding energies calculation well correlates with the change in clinical observation.Communicated by Ramaswamy H. Sarma.

ZAP70 Activation Compensates for Loss of Class IA PI3K Isoforms Through Activation of the JAK-STAT3 Pathway

BACKGROUND/AIM

Tyrosine kinases have crucial functions in cell signaling and proliferation. The phosphatidylinositol 3-kinase (PI3K) pathway is frequently deregulated in human cancer and is an essential regulator of cellular proliferation. We aimed to determine which tyrosine kinases contribute to resistance elicited by PI3K silencing and inhibition.

MATERIALS AND METHODS

To mimic catalytic inactivation of p110α/β, specific p110α (BYL719) and p110β (KIN193) inhibitors were used in addition to genetic knock-out in in vitro assays. Cell viability was assessed using crystal violet staining, whereas cellular transformation ability was analyzed by soft-agar growth assays.

RESULTS

Activated zeta chain of T-cell receptor-associated protein kinase 70 (ZAP70) generated resistance to PI3K inhibition. This resistance was via activation of the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) axis. We demonstrated that activated ZAP70 has a high transforming capability associated with the formation of malignant phenotype in untransformed cells and has the potential to be a tumor-initiating factor in cancer cells.

CONCLUSION

ZAP70 may be a potent driver of proliferation and transformation in untransformed cells and is implicated in resistance to PI3K inhibitors in cancer cells.

A concise review on tyrosine kinase targeted cancer therapy

Abstract:

The tyrosine kinase (TK) family is considered one of the important family members of the kinase family due to its important role in various cellular processes like cell growth, cell differentiation, apoptosis, etc. Mutation, overexpression, and dysfunction of tyrosine kinase receptors lead to the development of malignancy; thus, they are considered as one of the important targets for the development of anti-cancer molecules. The tyrosine kinase family is majorly divided into two classes; receptor and non-receptor tyrosine kinase. Both of the classes have an important role in the development of tumour cells. Currently, there are more than 40 FDA-approved tyrosine kinase inhibitors, which are used in the treatment of various types of cancers. Tyrosine kinase inhibitors mainly block the phosphorylation of tyrosine residue of the corresponding kinase substrate and so activation of downstream signalling pathways can be inhibited. The promising results of tyrosine kinase inhibitors in solid tumours provide a revolution in oncology research. In this article, we had summarized the role of some important members of the tyrosine kinase family in the development and progression of tumour cells and the significance of tyrosine kinase inhibitors in the treatment of various types of cancer.

Natural Kinase Inhibitors for the Treatment and Management of Endometrial/Uterine Cancer: Preclinical to Clinical Studies

Endometrial cancer (EC) is the sixth most prevalent type of cancer among women. Kinases, enzymes mediating the transfer of adenosine triphosphate (ATP) in several signaling pathways, play a significant role in carcinogenesis and cancer cells’ survival and proliferation. Cyclin-dependent kinases (CDKs) are involved in EC pathogenesis; therefore, CDK inhibitors (CDKin) have a noteworthy therapeutic potential in this type of cancer, particularly in EC type 1. Natural compounds have been used for decades in the treatment of cancer serving as a source of anticancer bioactive molecules. Many phenolic and non-phenolic natural compounds covering flavonoids, stilbenoids, coumarins, biphenyl compounds, alkaloids, glycosides, terpenes, and terpenoids have shown moderate to high effectiveness against CDKin-mediated carcinogenic signaling pathways (PI3K, ERK1/2, Akt, ATM, mTOR, TP53). Pharmaceutical regimens based on two natural compounds, trabectedin and ixabepilone, have been investigated in humans showing short and midterm efficacy as second-line treatments in phase II clinical trials. The purpose of this review is twofold: the authors first provide an overview of the involvement of kinases and kinase inhibitors in the pathogenesis and treatment of EC and then discuss the existing evidence about natural products’ derived kinase inhibitors in the management of the disease and outline relevant future research.

MicroRNAs as the critical regulators of tyrosine kinase inhibitors resistance in lung tumor cells

Lung cancer is the second most common and the leading cause of cancer related deaths globally. Tyrosine Kinase Inhibitors (TKIs) are among the common therapeutic strategies in lung cancer patients, however the treatment process fails in a wide range of patients due to TKIs resistance. Given that the use of anti-cancer drugs can always have side effects on normal tissues, predicting the TKI responses can provide an efficient therapeutic strategy. Therefore, it is required to clarify the molecular mechanisms of TKIs resistance in lung cancer patients. MicroRNAs (miRNAs) are involved in regulation of various pathophysiological cellular processes. In the present review, we discussed the miRNAs that have been associated with TKIs responses in lung cancer. MiRNAs mainly exert their role on TKIs response through regulation of Tyrosine Kinase Receptors (TKRs) and down-stream signaling pathways. This review paves the way for introducing a panel of miRNAs for the prediction of TKIs responses in lung cancer patients.

Fluorescence Lifetime Imaging Probes for Cell-Based Measurements of Enzyme Activity

Posttranslational modification (PTM) enzymes are important modulators of protein structure and function. They typically act by chemically modifying amino acids, often on side chain functional groups, to change the physiochemical landscape of the protein and thus its biophysical behavior. In particular, protein kinases are enzymes that transfer phosphate from ATP to serine, threonine, or tyrosine in protein substrates. They are key regulators of vital cellular pathways such as survival, proliferation, and apoptosis, and their dysregulation in the context of cancer has been widely investigated for the purpose of development of anticancer drugs. However, several critical questions pertaining to their physiology, such as heterogeneity of kinase signaling within and between cells, and other factors that may play into the mechanisms of drug resistance, remain unanswered. Many of the current strategies to measure kinase activity lack the scope, subcellular resolution, and real-time monitoring ability needed to obtain the type of information needed about their dynamics and localization in cells. While FRET-based biosensors are capable of dynamic single cell imaging, their applications can be limited by difficulties in multiplexing and the inherent inadequacies of steady state measurements. In this chapter, we describe our fluorescence lifetime imaging microscopy (FLIM) probe technology in which peptide kinase substrates, linked to cell-penetrating peptides and labeled with small molecule fluorophores, are used to report kinase activity through time-resolved fluorescence imaging to visualize and quantify changes to the probe's fluorescence lifetime. These can be multiplexed for more than one kinase at a time, and interpretation is not affected by differences in local intensity due to probe uptake and distribution or photobleaching. With careful choice of peptide substrate(s), fluorophore label, and imaging set-up, high specificity and spatiotemporal resolution can be achieved. Due to the mechanism by which the lifetime change occurs, this approach is compatible with other PTMs (such as acetylation, methylation), and so the considerations for kinase FLIM probe design described in this chapter should be broadly applicable for other PTMs as well.

The possible role of SRMS in colorectal cancer by bioinformatics analysis

BACKGROUND

Src-related kinase lacking C-terminal regulatory tyrosine and N-terminal myristoylation sites (SRMS) is a non-receptor tyrosine kinase that has been found to be overexpressed in various tumors. However, the role of SRMS in colorectal cancer (CRC) has not been well established.

METHODS

We evaluated the expression levels of SRMS in CRC using GEPIA, Oncomine, and HPA datasets. Survival information and gene expression data of CRC were obtained from The Cancer Genome Atlas (TCGA). Then, the association between SRMS and clinicopathological features was analyzed using UALCAN dataset. LinkedOmics was used to determine co-expression and functional networks associated with SRMS. Besides, we used TISIDB to assess the correlation between SRMS and immune signatures, including tumor-infiltrating immune cells and immunomodulators. Lastly, protein-protein interaction network (PPI) was established and the function enrichment analysis of the SRMS-associated immunomodulators and immune cell marker genes were performed using the STRING portal.

RESULTS

Compared to normal colorectal tissues, SRMS was found to be overexpressed in CRC tissues, which was correlated with a poor prognosis. In colon adenocarcinoma (COAD), the expression levels of SRMS are significantly correlated with pathological stages and nodal metastasis status. Functional network analysis suggested that SRMS regulates intermediate filament-based processes, protein autophosphorylation, translational initiation, and elongation signaling through pathways involving ribosomes, proteasomes, oxidative phosphorylation, and DNA replication. In addition, SRMS expression was correlated with infiltrating levels of CD4+ T cells, CD56dim, MEM B, Neutrophils, Th2, Th17, and Act DC. The gene ontology (GO) analysis of SRMS-associated immunomodulators and immune cell marker genes showed that they were mainly enriched in the immune microenvironment molecule-related signals. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of these genes indicated that they are involved in multiple cancer-related pathways.

CONCLUSIONS

SRMS is a promising prognostic biomarker and potential therapeutic target for CRC patients. In particular, SRMS regulates CRC progression by modulating cytokine-cytokine receptor interaction, chemokines, IL-17, and intestinal immune networks for IgA production signaling pathways among others. However, more studies are needed to validate these findings.

Tyrosine kinases regulate chondrocyte hypertrophy: promising drug targets for Osteoarthritis

Osteoarthritis (OA) is a major health problem worldwide that affects the joints and causes severe disability. It is characterized by pain and low-grade inflammation. However, the exact pathogenesis remains unknown and the therapeutic options are limited. In OA articular chondrocytes undergo a phenotypic transition becoming hypertrophic, which leads to cartilage damage, aggravating the disease. Therefore, a therapeutic agent inhibiting hypertrophy would be a promising disease-modifying drug. The therapeutic use of tyrosine kinase inhibitors has been mainly focused on oncology, but the Food and Drug Administration (FDA) approval of the Janus kinase inhibitor Tofacitinib in Rheumatoid Arthritis has broadened the applicability of these compounds to other diseases. Interestingly, tyrosine kinases have been associated with chondrocyte hypertrophy. In this review, we discuss the experimental evidence that implicates specific tyrosine kinases in signaling pathways promoting chondrocyte hypertrophy, highlighting their potential as therapeutic targets for OA.

Protein Kinases: Potential Drug Targets Against Schistosoma japonicum

Schistosoma japonicum (S. japonicum) infection can induce serious organ damage and cause schistosomiasis japonica which is mainly prevalent in Asia and currently one of the most seriously neglected tropical diseases. Treatment of schistosomiasis largely depends on the drug praziquantel (PZQ). However, PZQ exhibits low killing efficacy on juvenile worms and the potential emergence of its drug resistance is a continual concern. Protein kinases (PKs) are enzymes that catalyze the phosphorylation of proteins and can participate in many signaling pathways in vivo. Recent studies confirmed the essential roles of PKs in the growth and development of S. japonicum, as well as in schistosome-host interactions, and researches have screened drug targets about PKs from S. japonicum (SjPKs), which provide new opportunities of developing new treatments on schistosomiasis. The aim of this review is to present the current progress on SjPKs from classification, different functions and their potential to become drug targets compared with other schistosomes. The efficiency of related protein kinase inhibitors on schistosomes is highlighted. Finally, the current challenges and problems in the study of SjPKs are proposed, which can provide future guidance for developing anti-schistosomiasis drugs and vaccines.

Tyrosine kinases in the pathogenesis of tissue fibrosis in systemic sclerosis and potential therapeutic role of their inhibition

Systemic sclerosis (SSc) is an idiopathic autoimmune disease with a heterogeneous clinical phenotype ranging from limited cutaneous involvement to rapidly progressive diffuse SSc. The most severe SSc clinical and pathologic manifestations result from an uncontrolled fibrotic process involving the skin and various internal organs. The molecular mechanisms responsible for the initiation and progression of the SSc fibrotic process have not been fully elucidated. Recently it has been suggested that tyrosine protein kinases play a role. The implicated kinases include receptor-activated tyrosine kinases and nonreceptor tyrosine kinases. The receptor kinases are activated following specific binding of growth factors (platelet-derived growth factor, fibroblast growth factor, or vascular endothelial growth factor). Other receptor kinases are the discoidin domain receptors activated by binding of various collagens, the ephrin receptors that are activated by ephrins and the angiopoetin-Tie-2s receptors. The nonreceptor tyrosine kinases c-Abl, Src, Janus, and STATs have also been shown to participate in SSc-associated tissue fibrosis. Currently, there are no effective disease-modifying therapies for SSc-associated tissue fibrosis. Therefore, extensive investigation has been conducted to examine whether tyrosine kinase inhibitors (TKIs) may exert antifibrotic effects. Here, we review the role of receptor and nonreceptor tyrosine kinases in the pathogenesis of the frequently progressive cutaneous and systemic fibrotic alterations in SSc, and the potential of TKIs as SSc disease-modifying antifibrotic therapeutic agents.

Modifications of Plasma Membrane Organization in Cancer Cells for Targeted Therapy

Modifications of the composition or organization of the cancer cell membrane seem to be a promising targeted therapy. This approach can significantly enhance drug uptake or intensify the response of cancer cells to chemotherapeutics. There are several methods enabling lipid bilayer modifications, e.g., pharmacological, physical, and mechanical. It is crucial to keep in mind the significance of drug resistance phenomenon, ion channel and specific receptor impact, and lipid bilayer organization in planning the cell membrane-targeted treatment. In this review, strategies based on cell membrane modulation or reorganization are presented as an alternative tool for future therapeutic protocols.

Pancreatic Cancer: Recent Progress of Drugs in Clinical Trials

Pancreatic cancer is a highly malignant tumor and one of the primary causes of cancer-related death. Because pancreatic cancer is difficult to diagnose in the early course of the disease, most patients present with advanced lesions at the time of diagnosis, and only 20% of patients are eligible for surgery. Consequently, drug treatment has become extremely important. At present, the main treatment regimens for pancreatic cancer are gemcitabine and the FORFIRINOX and MPACT regimens. However, none of these regimens substantially improves the prognosis of patients with pancreatic cancer. Extensive efforts have been dedicated to the study of pancreatic cancer in recent years. With the development and clinical application of biological targeted drugs, the biological targeted treatment of tumors has been widely accepted. Therefore, this article used relevant clinical trial data to summarize the research progress of traditional chemotherapy drugs and biological targeted drugs for the treatment of pancreatic cancer.

The Seminiferous Epithelial Cycle of Spermatogenesis: Role of Non-receptor Tyrosine Kinases

Non-receptor tyrosine kinases (NRTKs) are implicated in various biological processes including cell proliferation, differentiation, survival, and apoptosis, as well as cell adhesion and movement. NRTKs are expressed in all mammals and in different cell types, with extraordinarily high expression in the testis. Their association with the plasma membrane and dynamic subcellular localization are crucial parameters in their activation and function. Many NRTKs are found in endosomal protein trafficking pathways, which suggests a novel mechanism to regulate the timely junction restructuring in the mammalian testis to facilitate spermiation and germ cell transport across the seminiferous epithelium.

Recent Advances in the Discovery of Multitargeted Tyrosine Kinase Inhibitors as Anticancer Agents

The treatment of cancer has been one of the most significant challenges for the medical field. Further research on the signal transduction pathway of tumor cells is driving the rapid development of antitumor agents targeting tyrosine kinases. However, most of the currently approved tyrosine kinase inhibitors based on the "single target/single drug" design are becoming less and less effective in the treatment of complex, heterogeneous, and multigenic cancers; this also results in resistance to chemotherapy. In contrast, multitargeted tyrosine kinase inhibitors (MT-TKIs) can effectively block multiple pathways of intracellular signal transduction. Therefore, they have therapeutic advantages over single-targeted inhibitors and have become a hotspot in antitumor drug research in recent years. This minireview summarizes recent advances in the discovery of MT-TKIs based on their chemical structures. In particular, we describe the kinase inhibitory and antitumor activity of promising compounds, as well as their structure - activity relationships (SARs).

Characterization of the Immunomodulatory Mechanism of a Pleurotus eryngii Protein by Isobaric Tags for Relative and Absolute Quantitation Proteomics

PEP 1b is a novel immunoregulatory protein isolated from Pleurotus eryngii, a popular edible mushroom. In this study, isobaric tags for relative and absolute quantitation (iTRAQ) approach and bioinformatics analysis were used to characterize the PEP-1b-induced proteome alterations in Raw 264.7 macrophage cells, to comprehensively excavate the molecular mechanisms involved in the immunoregulatory effects of PEP 1b. In comparison to the control group, PEP 1b treatment significantly changed the expression of 292 proteins, including 191 upregulated and 101 downregulated proteins. Bioinformatics analysis showed that PEP-1b-regulated proteins were involved in 437 biological process domains, 131 cellular component domains, and 90 molecular function domains. Moreover, PEP 1b played the role of immunomodulator by mainly modulating the Rap1 signaling pathway, Wnt signaling pathway, Ras signaling pathway, and PI3K-Akt signaling pathway. Interestingly, PEP 1b regulated the proteins involved in the immune system, signal transduction, and transport processes, which were related to the immunoregulatory effects of PEP 1b. The western blotting analysis confirmed that the immune-boosting activities of PEP 1b were associated with modulating the expression of Sqstm1, Cox2, Rap1b, and Pyk2. The current research provided a comprehensive understanding of the immunoregulatory effects and molecular mechanisms involved in the PEP 1b supplementation.

Compounds from Natural Sources as Protein Kinase Inhibitors

The advantage of natural compounds is their lower number of side-effects when compared to most synthetic substances. Therefore, over the past several decades, the interest in naturally occurring compounds is increasing in the search for new potent drugs. Natural compounds are playing an important role as a starting point when developing new selective compounds against different diseases. Protein kinases play a huge role in several diseases, like cancers, neurodegenerative diseases, microbial infections, or inflammations. In this review, we give a comprehensive view of natural compounds, which are/were the parent compounds in the development of more potent substances using computational analysis and SAR studies.

Abrocitinib for the treatment of atopic dermatitis

INTRODUCTION

Janus kinase (JAK) inhibitors are emerging treatments in dermatology. Also known as JAKinibs, these agents target JAK-signal transducers and activators of transcription (JAK-STAT) pathway for intracellular signaling. Among the various immune-mediated inflammatory skin diseases that the JAK-STAT pathway plays a role in, atopic dermatitis (AD) is an important one. AD has a complex and multifactorial pathophysiology that is not fully understood. Immune dysregulation can result in epidermal barrier disruption and intensify atopic dermatitis. The newly developed abrocitinib (PF-04965842) selectively inhibits the JAK1 protein, which is believed to modulate cytokines involved in AD pathophysiology.

AREAS COVERED

This work is a review of the current literature related to abrocitinib, including the phase I, II, and III clinical trials, for the treatment of AD. Immunological considerations of abrocitinib and JAK inhibition are also explored.

EXPERT OPINION

Abrocitinib is among the first JAK inhibitors evaluated for the treatment of AD. Similar to other JAKinhibs that mechanistically block the signaling of several cytokines, abrocitinib possesses both positive and negative clinical attributes. Nonetheless, the risk-benefit profile of abrocitinib remains favorable. Up to 61% of AD patients achieve an EASI 75 response while a minority of responding patients experience mild to moderate symptoms related to tolerability.

Epoxyquinophomopsins A and B from endophytic fungus Phomopsis sp. and their activity against tyrosine kinase

Two new quinone derivatives, epoxyquinophomopsins A (1) and B (2), were purified from the EtOAc extract of endophytic fungus Phomopsis sp isolated from Morus cathayana. The structures of both compounds were determined based on 1D and 2D NMR and mass spectral data, as well as by x-ray diffraction analysis for 1. Compounds 1 and 2 were screened against eight receptor- (RTKs) and eight non-receptor tyrosine kinases (nRTKs). Both compounds showed strong inhibitory properties against Bruton's Tyrosine Kinase (nRTK) with their kinase activity were 19% and 20%, respectively. Only compound 1 that showed strong inhibitory properties against RTKs EGFR and HER-4 with its kinase activity were 16 and 15%, respectively. Thus, both compounds have potential as tyrosine kinase inhibitors.

Abrocitinib: a potential treatment for moderate-to-severe atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is a common and debilitating dermatosis that often impacts the physical and psychological quality of life in children and adults. A limited number of treatment options are available for AD, and often these treatments result in an insufficient response or may be contraindicated for some patients. This treatment gap creates an increasing demand for alternative AD therapies. The Janus kinase (JAK)-signal transducers and activators of transcription (STAT) pathway is known to play a critical role in the dysregulation of immune responses in AD. Inhibition of the JAK enzymes in the JAK-STAT pathway has shown potential for the treatment of this chronic skin condition.

AREAS COVERED

We review the evolving efficacy and safety profile of abrocitinib, an oral JAK1 inhibitor, in the treatment of AD based on the data available from phase I, II, and III clinical trials.

EXPERT OPINION

Evidence supports clinical efficacy, improved pruritus and an acceptable safety profile, making abrocitinib a viable alternative to conventional AD therapies. Pivotal phase III trials included subjects aged 12 years and above, providing a new mechanism of action for future treatment of adolescent and adult AD. Further investigations are required to have a thorough understanding of abrocitinib in the treatment of AD.

Anti-tumor Drug Targets Analysis: Current Insight and Future Prospect

The incidence and mortality of malignant tumors are on the rise, which has become the second leading cause of death in the world. At present, anti-tumor drugs are one of the most common methods for treating cancer. In recent years, with the in-depth study of tumor biology and related disciplines, it has been gradually discovered that the essence of cell carcinogenesis is the infinite proliferation of cells caused by the disorder of cell signal transduction pathways, followed by a major shift in the concept of anti-tumor drugs research and development. The focus of research and development is shifting from traditional cytotoxic drugs to a new generation of anti-tumor drugs targeted at abnormal signaling system targets in tumor cells. In this review, we summarize the targets of anti-tumor drugs and analyse the molecular mechanisms of their effects, which lay a foundation for subsequent treatment, research and development.

Cumulative mechanism of several major imatinib-resistant mutations in Abl kinase

Despite the outstanding success of the cancer drug imatinib, one obstacle in prolonged treatment is the emergence of resistance mutations within the kinase domain of its target, Abl. We noticed that many patient-resistance mutations occur in the dynamic hot spots recently identified to be responsible for imatinib's high selectivity toward Abl. In this study, we provide an experimental analysis of the mechanism underlying drug resistance for three major resistance mutations (G250E, Y253F, and F317L). Our data settle controversies, revealing unexpected resistance mechanisms. The mutations alter the energy landscape of Abl in complex ways: increased kinase activity, altered affinity, and cooperativity for the substrates, and, surprisingly, only a modestly decreased imatinib affinity. Only under cellular adenosine triphosphate (ATP) concentrations, these changes cumulate in an order of magnitude increase in imatinib's half-maximal inhibitory concentration (IC50). These results highlight the importance of characterizing energy landscapes of targets and its changes by drug binding and by resistance mutations developed by patients.

p28 Bacterial Peptide, as an Anticancer Agent

Cancer remains a major cause of morbidity and mortality irrespective of the type of conventional chemotherapy. Therefore, there is an urgent need for new and effective anticancer therapeutic agents. Bacterial proteins and their derivative peptides appear as a promising approach for cancer treatment. Several, including an amphipathic, α-helical, 28-amino acid peptide derived from azurin, a 128-amino acid copper-containing redox protein secreted from Pseudomonas aeruginosa, show clinical promise in the treatment of adult and pediatric solid tumors. The peptide, p28, is a post-translational, multi-target anticancer agent that preferentially enters a wide variety of solid tumor cells. Mechanistically, after entry, p28 has two major avenues of action. It binds to both wild-type and mutant p53 protein, inhibiting constitutional morphogenic protein 1 (Cop1)-mediated ubiquitination and proteasomal degradation of p53. This results in increased levels of p53, which induce cell-cycle arrest at G2/M and an eventual apoptosis that results in tumor cell shrinkage and death. In addition, p28 also preferentially enters nascent endothelial cells and decreases the phosphorylation of FAK and Akt inhibiting endothelial cell motility and migration. Here, we review the current basic and clinical evidence suggesting the potential of p28 as a cancer therapeutic peptide.

Metastatic disease in head & neck oncology

The head and neck district represents one of the most frequent sites of cancer, and the percentage of metastases is very high in both loco-regional and distant areas. Prognosis refers to several factors: a) stage of disease; b) loco-regional relapses; c) distant metastasis. At diagnosis, distant metastases of head and neck cancers are present in about 10% of cases with an additional 20-30% developing metastases during the course of their disease. Diagnosis of distant metastases is associated with unfavorable prognosis, with a median survival of about 10 months. The aim of the present review is to provide an update on distant metastasis in head and neck oncology. Recent achievements in molecular profiling, interaction between neoplastic tissue and the tumor microenvironment, oligometastatic disease concepts, and the role of immunotherapy have all deeply changed the therapeutic approach and disease control. Firstly, we approach topics such as natural history, epidemiology of distant metastases and relevant pathological and radiological aspects. Focus is then placed on the most relevant clinical aspects; particular attention is reserved to tumours with distant metastasis and positive for EBV and HPV, and the oligometastatic concept. A substantial part of the review is dedicated to different therapeutic approaches. We highlight the role of immunotherapy and the potential effects of innovative technologies. Lastly, we present ethical and clinical perspectives related to frailty in oncological patients and emerging difficulties in sustainable socio-economical governance.

Etiologic Role of Kinases in the Progression of Human Cancers and Its Targeting Strategies

Cancer is one of the dominant causes of death worldwide while lifelong prognosis is still inauspicious. The maturation of the cancer is seen as a process of transformation of a healthy cell into a tumor-sensitive cell, which is held entirely at the cellular, molecular, and genetic levels of the organism. Tyrosine kinases can play a major, etiologic role in the inception of malignancy and devote to the uncontrolled proliferation of cancerous cells and the progression of a tumor as well as the development of metastatic disease. Angiogenesis and oncogene activation are the major event in cell proliferation. The growth of a tumor and metastasis are fully depending on angiogenesis and lymphangiogenesis triggered by chemical signals from tumor cells in a phase of rapid growth. Tyrosine kinase inhibitors are compounds that inhibit tyrosine kinases and effective in targeting angiogenesis and blocking the signaling pathways of oncogenes. Small molecule tyrosine kinase inhibitors like afatinib, erlotinib, crizotinib, gefitinib, and cetuximab are shown to a selective cut off tactic toward the constitutive activation of an oncogene in tumor cells, and thus contemplated as promising therapeutic approaches for the diagnosis of cancer and malignancies.

Assays for tyrosine phosphorylation in human cells

Tyrosine kinases are important for many cellular processes and disruption of their regulation is a factor in diseases like cancer, therefore they are a major target of anticancer drugs. There are many ways to measure tyrosine kinase activity in cells by monitoring endogenous substrate phosphorylation, or by using peptide substrates and incubating them with cell lysates containing active kinases. However, most of these strategies rely on antibodies and/or are limited in how accurately they model the intracellular environment. In cases in which activity needs to be measured in cells, but endogenous substrates are not known and/or suitable phosphospecific antibodies are not available, cell-deliverable peptide substrates can be an alternative and can provide information on activation and inhibition of kinases in intact, live cells. In this chapter, we review this methodology and provide a protocol for measuring Abl kinase activity in human cells using enzyme-linked immunosorbent assay (ELISA) with a generic antiphosphotyrosine antibody for detection.

Non-receptor tyrosine kinase signaling in autoimmunity and therapeutic implications

Autoimmune diseases are characterized by impaired immune tolerance towards self-antigens, leading to enhanced immunity to self by dysfunctional B cells and/or T cells. The activation of these cells is controlled by non-receptor tyrosine kinases (NRTKs), which are critical mediators of antigen receptor and cytokine receptor signaling pathways. NRTKs transduce, amplify and sustain activating signals that contribute to autoimmunity, and are counter-regulated by protein tyrosine phosphatases (PTPs). The function of and interaction between NRTKs and PTPs during the development of autoimmunity could be key points of therapeutic interference against autoimmune diseases. In this review, we summarize the current state of knowledge of the functions of NRTKs and PTPs involved in B cell receptor (BCR), T cell receptor (TCR), and cytokine receptor signaling pathways that contribute to autoimmunity, and discuss their targeting for therapeutic approaches against autoimmune diseases.

Adding Nanotechnology to the Metastasis Treatment Arsenal

Metastasis is a major cause of cancer-related mortality, accounting for 90% of cancer deaths. The explosive growth of cancer biology research has revealed new mechanistic network information and pathways that promote metastasis. Consequently, a large number of antitumor agents have been developed and tested for their antimetastatic efficacy. Despite their exciting cytotoxic effects on tumor cells in vitro and antitumor activities in preclinical studies in vivo, only a few have shown potent antimetastatic activities in clinical trials. In this review, we provide a brief overview of current antimetastatic strategies that show clinical efficacy and review nanotechnology-based approaches that are currently being incorporated into these therapies to mitigate challenges associated with treating cancer metastasis.

c-Abl regulates YAPY357 phosphorylation to activate endothelial atherogenic responses to disturbed flow

Local flow patterns determine the uneven distribution of atherosclerotic lesions. This research aims to elucidate the mechanism of regulation of nuclear translocation of Yes-associated protein (YAP) under oscillatory shear stress (OSS) in the atheroprone phenotype of endothelial cells (ECs). We report here that OSS led to tyrosine phosphorylation and strong, continuous nuclear translocation of YAP in ECs that is dependent on integrin α5β1 activation. YAP overexpression in ECs blunted the anti-atheroprone effect of an integrin α5β1-blocking peptide (ATN161) in Apoe-/- mice. Activation of integrin α5β1 induced tyrosine, but not serine, phosphorylation of YAP in ECs. Blockage of integrin α5β1 with ATN161 abolished the phosphorylation of YAP at Y357 induced by OSS. Mechanistic studies showed that c-Abl inhibitor attenuated the integrin α5β1-induced YAP tyrosine phosphorylation. Furthermore, the phosphorylation of c-Abl and YAPY357 was significantly increased in ECs in atherosclerotic vessels of mice and in human plaques versus normal vessels. Finally, bosutinib, a tyrosine kinase inhibitor, markedly reduced the level of YAPY357 and the development of atherosclerosis in Apoe-/- mice. The c-Abl/YAPY357 pathway serves as a mechanism for the activation of integrin α5β1 and the atherogenic phenotype of ECs in response to OSS, and provides a potential therapeutic strategy for atherogenesis.

Specific Expression of a New Bruton Tyrosine Kinase Isoform (p65BTK) in the Glioblastoma Gemistocytic Histotype

Bruton's tyrosine-kinase (BTK) is a non-receptor tyrosine kinase recently associated with glioma tumorigenesis and a novel prognostic marker for poor survival in patients with glioma. The p65BTK is a novel BTK isoform involved in different pathways of drug resistance of solid tumors, thus we aimed to investigate the expression and the putative role of p65BTK in tumors of the central nervous system (CNS). We selected a large cohort of patients with glial tumors (n = 71) and analyzed the expression of p65BTK in different histotypes and correlation with clinical parameters. Sections were stained with glial fibrillary acidic protein (GFAP), p53, epidermal growth factor receptor (EGFR), S100, vimentin, and epithelial membrane antigen (EMA) antibodies. Glioma stem cell (GSC) lines, isolated from glioblastoma multiforme (GBM), were treated with different concentrations of ibrutinib, a specific inhibitor of BTK, in order to evaluate their metabolic activity, mitotic index and mortality. Moreover, an orthotopic xenotransplant of GSC from human GBM was used to evaluate the expression of p65BTK in the brain of immunodeficient mice. p65BTK was expressed in GSC and in gemistocytes in human gliomas at different histological grade. We found a significant correlation between BTK expression and low-grade (LG) tumors (p ≤ 0.05) and overall survival (OS) of patients with grade III gliomas (p ≤ 0.05), suggestive of worst prognosis. Interestingly, the expression of p65BTK remained restricted exclusively to gemistocytic cells in the xenograft mouse model. Ibrutinib administration significantly reduced metabolic activity and mitotic index and increased mortality in GSC, highlighting the specific role of p65BTK in cell proliferation and survival. In conclusion, our data demonstrated that p65BTK is expressed in glioma tumors, restricted to gemistocytic cells, has a key role in GSC and has a bad prognostic value, thus highlighting the importance of future research for targeted therapy of human gliomas.

Targeting tyrosine kinases for treatment of ocular tumors

Uveal melanoma is the most common intraocular primary malignant tumor in adults, and retinoblastoma is the one in children. Current mainstay treatment options include chemotherapy using conventional drugs and enucleation, the total removal of the eyeball. Targeted therapies based on profound understanding of molecular mechanisms of ocular tumors may increase the possibility of preserving the eyeball and the vision. Tyrosine kinases, which modulate signaling pathways regarding various cellular functions including proliferation, differentiation, and attachment, are one of the attractive targets for targeted therapies against uveal melanoma and retinoblastoma. In this review, the roles of both types of tyrosine kinases, receptor tyrosine kinases and non-receptor tyrosine kinases, were summarized in relation with ocular tumors. Although the conventional treatment options for uveal melanoma and retinoblastoma are radiotherapy and chemotherapy, respectively, specific tyrosine kinase inhibitors will enhance our armamentarium against them by controlling cancer-associated signaling pathways related to tyrosine kinases. This review can be a stepping stone for widening treatment options and realizing targeted therapies against uveal melanoma and retinoblastoma.