Protein Kinase Inhibitor Research Articles

Recent Advances in Pyrazole-based Protein Kinase Inhibitors as Emerging Therapeutic Targets.

Pyrazole-scaffold protein kinase inhibitors (PKIs) have emerged as promising therapeutic agents for the treatment of various diseases, such as cancer, inflammatory disorders, and neurological diseases. This review article provides an overview of the pharmacological properties of pyrazole-scaffold PKIs, including their mechanism of action, selectivity, potency, and toxicity. The article also summarizes the recent developments in the design and synthesis of pyrazole-scaffold PKIs, highlighting the structural features and modifications that contribute to their pharmacological activity. In addition, the article discusses the preclinical and clinical studies of pyrazole-scaffold PKIs, including their efficacy, safety, and pharmacokinetic properties. A comprehensive search has been conducted on several online patent databases, including the United States Patent and Trademark Office (USPTO), the European Patent Office (EPO), and the World Intellectual Property Organization (WIPO). The search was conducted using pyrazole as the keyword. The search was limited to patents filed between 2015 and 2022. Patents were included if they involved articles in the fields of protein kinase inhibitors, and included literature on some pyrazoles and their pharmacological activities. Data were extracted from each included patent on the following variables: patent title, patent number, inventors, assignee, filing date, publication date, patent type, and field of invention. Data were extracted from each patent using a standardized form to ensure consistency and accuracy. The design and pharmacological evaluation of organic compounds containing pyrazole structure as biologically active substances have been done, and the key structures from the pharmacological data obtained as protein kinase inhibitors have been addressed in detail. The review concludes with a discussion on the current challenges and future directions for the development of pyrazole-scaffold PKIs as therapeutic agents. Overall, this review article provides a comprehensive summary of the pharmacological properties of pyrazole-scaffold PKIs, which will be of interest to researchers and clinicians in the field of drug discovery and development.

Thrombospondin 1 Mediates Autophagy Upon Inhibition of the Rho-Associated Protein Kinase Inhibitor

Age-related macular degeneration (AMD) is a degenerative eye disease leading to central vision loss and is characterized by dysregulated autophagy of the retinal pigment epithelium (RPE) layer. Recent studies have suggested that rho-associated protein kinase (ROCK) inhibitors may enhance autophagy in neurodegenerative diseases and promote the survival of RPE cells. This study investigated the effect of ROCK inhibitors on autophagy gene expression and autophagic vacuole formation in a human RPE (ARPE-19) cell line. The highly selective and potent ROCK inhibitor Y-39983 enhanced the expression of autophagy genes in ARPE-19 cells and increased autophagic vacuole formation. A proteomic analysis using mass spectrometry was performed to further characterize the effects of ROCK inhibition at the protein level. Y-39983 downregulated thrombospondin-1 (THBS1), and suppression of THBS1 in ARPE-19 cells resulted in an increase in autophagic vacuole formation. Our data showed that ROCK inhibitor-induced autophagy was mediated by THBS1 downregulation. We identified ROCK and THBS1 as potential novel therapeutic targets in AMD.

Age differences in the treatment of lung cancer-a cohort study among 42,000 patients from Germany.

We aimed to describe treatment of lung cancer patients in Germany based on health claims data, focusing particularly on differences by age. Using the German Pharmacoepidemiological Research Database (GePaRD, ~ 20% of the German population) we identified lung cancer patients diagnosed in 2015-2018 based on a previously developed algorithm and followed them until death, end of continuous insurance or end of 2020. We described initial treatment patterns after diagnosis and survival, stratified among others by age. We included 42,629 incident lung cancer patients (58% male). Surgery within three months after diagnosis was performed in 36%, 31%, 29% and 18% of patients aged < 50, 50-69, 70-79 and ≥ 80, respectively. Among patients without surgery, systemic therapy was administered in 77%, 72%, 54% and 25% of patients aged < 50, 50-69, 70-79 and ≥ 80, respectively. Monoclonal antibodies were administered in 15-30% of patients across age groups, and 4% to 15% received protein kinase inhibitors. Overall, 21% of patients remained untreated. In the age groups < 50, 50-69, 70-79 and ≥ 80, this proportions was 9%, 12%, 22% and 48%, respectively. In conclusion, our study provides a comprehensive overview of the therapy of lung cancer patients in Germany and quantitatively demonstrates the considerable differences between age groups. In terms of clinical cancer registration, the results are useful to estimate the completeness of data for the different types of treatment.

Inhibition of protein kinase D and its substrate phosphatidylinositol-4 kinase III beta blocks common human coronavirus replication.

Human coronaviruses can lead to a range of clinical symptoms, from asymptomatic infection to severe illness and death, with a limited array of antiviral drugs available. Protein kinase D (PKD) is involved in various cellular processes, such as cell proliferation, apoptosis, and membrane fission of the Golgi apparatus. However, the specific role of PKD in the human coronavirus life cycle remains unclear. In this study, we found that PKD inhibitors effectively attenuated human coronavirus replication at the trans-Golgi network (TGN) stage in the viral life cycle. Furthermore, inhibiting PKD reduced PI4KIIIβ activation, thereby blocking viral replication in the host cells. Importantly, PI4KIIIβ inhibitors also blocked human coronavirus replication. Thus, PKD may represent a promising therapeutic target against both current circulating and future emerging coronaviruses.

Abstract A004: RNA splicing alterations in the development of acquired MAPKi resistance in melanoma

Abstract The standard treatment for melanoma with a BRAF mutation involves Mitogen-Activated Protein Kinase inhibitors (MAPKi), which target the aberrant MAPK signaling pathway. Although patients initially respond well to this therapy, many develop acquired resistance over time. This resistance can be attributed to various altered signaling pathways, including the reactivation of the MAPK pathway, activation of alternative survival pathways like PI3K/PTEN/AKT, engagement of receptor tyrosine kinases (RTKs) such as PDGFRβ and EGFR, and developmental pathways. Despite extensive omics studies aimed at deciphering the mechanisms behind acquired resistance, the specific alterations within these pathways remain poorly understood. To gain further insights into acquired MAPKi resistance in melanoma, we explored the role of RNA splicing events by analyzing publicly available datasets of pre- and post-MAPKi treated melanoma from patient-derived cell lines and in vitro studies using PDX models. We investigated differential transcript usage (DTU) to detect specific splice variants altered during the development of resistance. Our analysis revealed significant transcript alterations during on-treatment that reverted to baseline states once resistance was established, underscoring the dynamic and adaptive nature of these changes. Genes with DTU were enriched in pathways related to MAPKi resistance, such as the MAPKi signaling pathway, PI3K/AKT pathway, and signaling by RTKs. Furthermore, the DTU-centered analysis provided better insights into MAPKi resistance mechanisms compared to standard differential gene expression (DEG) analysis, with DTUs showing higher enrichment scores in MAPKi resistance-related pathways. Further, identifying developmental splicing signatures highlights the complexity of MAPKi resistance, as it reveals significant upregulation of transcripts associated with embryonic melanoblast stem cells (MSCs) among the altered transcripts in on-treatment cell lines. This reprogramming through RNA splicing may confer an adaptive advantage, enabling melanoma cells to revert to a more plastic, stem-like state, with developmental splicing events playing a crucial role in the adaptive response to MAPKi therapy. Next, using a regulatory model based on the expression of splicing factors (SFs), we accurately predicted transcript alterations in on-treatment samples and identified key SFs. Our study highlights the crucial role of RNA splicing in the adaptive response of melanoma cells to MAPKi treatment. These insights pave the way for future research and therapeutic strategies focusing on RNA splicing to combat drug resistance in cancer. Citation Format: Sumit Mukherjee, Arashdeep Singh, Hyunjeong Joo, Sumeet Patiyal, Hyungsoo Kim, Lipika R. Pal, Kun Wang, Chi-Ping Day, Ze’ev A Ronai, Eytan Ruppin, Sridhar Hannenhalli. RNA splicing alterations in the development of acquired MAPKi resistance in melanoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr A004.

Mitogen-activated protein kinase dependent presynaptic potentiation in the lateral habenula mediates depressive-like behaviors in rats.

Emerging evidence suggests that the enhanced activity of lateral habenula (LHb) is involved in depressive disorders. This abnormal potentiation of LHb neurons was shown to originate from presynaptic alterations; however, the mechanisms underlying this presynaptic enhancement and physiological consequences are yet to be elucidated. Previously, we reported that presynaptic transmission in the LHb is temporally rhythmic, showing greater activity in the afternoon than in the morning. Here, we used a learned helpless rodent model of depression to show that exposure to a stressor or incubation with the stress hormone, corticosterone, abolished the presynaptic temporal variation in the LHb. In addition, selective inhibition of mitogen-activated protein kinase (MAPK) kinase (MAPKK, MEK) activity in the LHb restored the presynaptic alteration even after stress exposure. Moreover, we observed a slight increase in phosphorylated synapsin I after stress exposure. Finally, we found that a blockade of MAPK signaling before stress exposure successfully prevented the depression-like behaviors, including behavioral despair and helplessness, in an acute learned helpless animal model of depression. Our study delineates the cellular and molecular mechanisms responsible for the abnormal presynaptic enhancement of the LHb in depression, which may mediate depressive behaviors.

Avenanthramides Ameliorate Insulin Resistance by Modulating Gluconeogenesis and Glycogen Synthesis in HepG2 Cells.

Diabetes mellitus (DM) is a multifaceted metabolic condition, mainly defined by elevated blood glucose levels. A feature of type 2 DM includes insulin resistance (IR), which involves impairments within the insulin signaling pathways. Avenanthramides (AVNs) are phenolic alkaloids found in Avena sativa L. The major AVNs are AVN A, AVN B, and AVN C. They have been reported to offer benefits in preventing inflammation, cancer, and cardiovascular diseases. However, the effects of AVNs on the liver glucose metabolism pathways remain unknown. This study examined the effects and underlying mechanisms through which AVNs alleviate IR induced by free fatty acid (FFA) in HepG2 cells. The results indicated that FFA treatment significantly decreased glucose consumption by 34.54% compared to the control. However, treatments with AVN A, B, and C at 100 μM increased glucose uptake by 57.93%, 58.28%, and 53.10%, respectively, compared to FFA treatment alone. This effect occurs through the increased expression of glucose transporter 4. Furthermore, AVNs significantly enhanced the glycogen content. AVNs induced increased phosphorylation of insulin receptor substrate-1 (IRS-1), phosphatidylinositol-3-kinase (PI3K), and protein kinase B (Akt). AVNs treatment decreased the levels of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase in HepG2 cells. This effect was attributed to AMP-activated protein kinase activation and inhibition of forkhead box protein O1. Collectively, these results suggest that AVNs regulate glucose metabolism by activating the IRS-1/PI3K/Akt pathway, which is related to glycogen synthesis, and by inhibiting key molecules that promote gluconeogenesis.

INNV-12. CUTANEOUS TOXICITIES OF MITOGEN-ACTIVATED PROTEIN KINASE INHIBITORS IN CHILDREN AND YOUNG ADULTS WITH NEUROFIBROMATOSIS-1

Abstract BACKGROUND Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder which commonly causes neoplasms leading to disfigurement or dysfunction. Mitogen-activated protein kinase inhibitors (MEKi) are generally well-tolerated treatments which target neural tumor progression in patients with NF1. Cutaneous adverse events (CAEs) are common and may hinder patients’ abilities to remain on treatment, particularly in children. We aim to characterize CAEs secondary to MEKi treatment in pediatric and young adult patients with NF1. METHODS We reviewed institutional medical records of patients under 30 years with a diagnosis of “NF1,” “NF2,” or “other neurofibromatoses” on MEKi therapy between January 1, 2019 and June 1, 2022. We recorded the time-to-onset, type, and distribution of CAEs, non-cutaneous adverse events (AEs), AE management, and tumor response. RESULTS The median age of 40 patients with NF1 was 14 years old. Tumor types included low-grade gliomas (51%) and plexiform neurofibromas (38%). MEKi used included selumetinib (69%), trametinib (25%), and mirdametinib (6%) (Table 1). A total of 74 CAEs occurred, with 28 cases of acneiform rash (38%) (Figure 1). Twenty-three out of the 28 cases of acneiform eruption were in post-pubertal patients (82.1%). Other common CAEs were paronychia, seborrheic dermatitis, eczema, xerosis, and oral mucositis. The most common treatments included oral antibiotics and topical corticosteroids. Most patients had clinical (stable or improved) tumor response (71%) while 29% had tumor progression while on a MEKi (Table 2). There was no significant association between CAE presence and tumor response (p=0.39). CONCLUSIONS MEK inhibitors have been demonstrated as a valuable treatment, but CAEs complicate the ability to stay on the treatment. Most patients in our cohort developed a CAE, demonstrating its prevalence in this population. Improvement in characterization of MEKi toxicities and their management is important to develop treatment guidelines for pediatric and young adult patients with NF1 on MEKi therapy.

Exploring phytochemical inhibitors of protein kinase C alpha for therapeutic targeting of Alzheimer's disease.

Alzheimer's disease (AD) is characterized by neurodegeneration linked to amyloid-β (Aβ) plaques and tau protein tangles. Protein kinase C alpha (PKCα) plays a crucial role in modulating amyloid-β protein precursor (AβPP) processing, potentially mitigating AD progression. Consequently, PKCα stands out as a promising target for AD therapy. Despite the identification of numerous inhibitors, the pursuit of more effective and precisely targeted PKCα inhibitors remains crucial. In this study, we employed an integrated virtual screening approach of molecular docking and molecular dynamics (MD) simulations to identify phytochemical inhibitors of PKCα from the IMPPAT database. Molecular docking screening via InstaDock identified compounds with strong binding affinities to PKCα. Subsequent ADMET and PASS analyses filtered out compounds with favorable pharmacokinetic profiles. Interaction analysis using Discovery Studio Visualizer and PyMOL further elucidated binding conformations of selected compounds with PKCα. Top hits underwent 200 ns MD simulations using GROMACS to validate stability of the interactions. Finally, we propose two phytochemicals, Kammogenin and Imperialine, with appreciable drug-likeliness and binding potential with PKCα. Taken together, the findings suggest Kammogenin and Imperialine as potential PKCα inhibitors, highlighting their therapeutic promise for AD after further validation.

α-Triazolylboronic Acids: A Novel Scaffold to Target FLT3 in AML.

The treatment of acute myeloid leukemia (AML) presents a challenge to current therapies because of the development of drug resistance. Genetic mutation of FMS-like tyrosine kinase-3 (FLT3) is a target of interest for AML treatment, but the use of FLT3-targeting agents on AML patients has so far resulted in poor overall clinical outcomes.[1] The incorporation of the boronic group in a drug scaffold could enhance the bioavailability and pharmacokinetic profile of conventional anticancer chemotypes. Boronic acids represent an intriguing and unexplored class of compounds in the context of AML, and they are only scantly reported as inhibitors of protein kinases. We identified α-triazolylboronic acids as a novel chemotype for targeting FLT3 by screening a library of structurally heterogeneous in-house boronic acids. Selected compounds show low micromolar activities on enzymatic and cellular assays, selectivity against control cell lines and a recurring binding mode in in-silico studies. Furthermore, control analogues synthesized ad hoc and lacking the boronic acid are inactive, confirming that this group is essential for the activity of the series. All together, these results suggest α-triazolylboronic acids could be a promising novel chemotype for FLT3 inhibition, laying the ground for the design of further compounds.

Thieno[3,2-b]pyridine: Attractive scaffold for highly selective inhibitors of underexplored protein kinases with variable binding mode.

Protein kinases are key regulators of numerous biological processes and aberrant kinase activity can cause various diseases, particularly cancer. Herein, we report the identification of new series of highly selective kinase inhibitors based on the thieno[3,2-b]pyridine scaffold. The weak interaction of the thieno[3,2-b]pyridine core with the kinase hinge region allows for profoundly different binding modes all of which maintain high kinome-wide selectivity, as illustrated by the isomers MU1464 and MU1668. Thus, this core structure provides a template of ATP-competitive but not ATP-mimetic inhibitors that are anchored at the kinase back pocket. Mapping the chemical space around the central thieno[3,2-b]pyridine pharmacophore afforded highly selective inhibitors of the kinase Haspin, exemplified by the compound MU1920 that fulfils criteria for a quality chemical probe and is suitable for use in in vivo applications. However, despite the role of Haspin in mitosis, the inhibition of Haspin alone was not sufficient to elicit cytotoxic effect in cancer cells. The thieno[3,2-b]pyridine scaffold can be used in a broader context, as a basis of inhibitors targeting other underexplored protein kinases, such as CDKLs.

Thieno[3,2‐b]pyridine: Attractive scaffold for highly selective inhibitors of underexplored protein kinases with variable binding mode

Protein kinases are key regulators of numerous biological processes and aberrant kinase activity can cause various diseases, particularly cancer. Herein, we report the identification of new series of highly selective kinase inhibitors based on the thieno[3,2‐b]pyridine scaffold. The weak interaction of the thieno[3,2‐b]pyridine core with the kinase hinge region allows for profoundly different binding modes all of which maintain high kinome‐wide selectivity, as illustrated by the isomers MU1464 and MU1668. Thus, this core structure provides a template of ATP‐competitive but not ATP‐mimetic inhibitors that are anchored at the kinase back pocket. Mapping the chemical space around the central thieno[3,2‐b]pyridine pharmacophore afforded highly selective inhibitors of the kinase Haspin, exemplified by the compound MU1920 that fulfils criteria for a quality chemical probe and is suitable for use in in vivo applications. However, despite the role of Haspin in mitosis, the inhibition of Haspin alone was not sufficient to elicit cytotoxic effect in cancer cells. The thieno[3,2‐b]pyridine scaffold can be used in a broader context, as a basis of inhibitors targeting other underexplored protein kinases, such as CDKLs.

Chemical genetics analysis suggests the involvement of Aurora kinase and MAPKs in aluminum-induced malate secretion in Arabidopsis.

Chemical genetics is a multidisciplinary research method. In this study, it is used to screen compounds that promote aluminum-induced malate secretion in Arabidopsis thaliana. Inhibition of p38 mitogen-activated protein kinase (p38 MAPK; LY2228820) significantly increased the transcription of Arabidopsis thaliana aluminum-activated malate transporter 1 (AtALMT1) and sensitive to proton rhizotoxicity 1 (STOP1)-regulated genes, multidrug and toxic compound extrusion and aluminum sensitive 3, but not AtSTOP1 and the Al-biomarker genes At3g28510, At5g13320, suggesting that LY2228820 increased the early expression of STOP1-regulated genes without affecting AtSTOP1 expression. Inhibition of p38 MAPK (LY2228820) and Aurora A (MLN8237) increased aluminum-activated malate transport via AtALMT1, suggesting that both MLN8237 and LY2228820 interfere with AtALMT1 activity. An increase in root elongation was also observed in Arabidopsis after applying compounds LY2228820 and MLN8237. Thus, both LY2228820 and MLN8237 may play important roles in alleviating the inhibitory effects of aluminum on roots.

Emerging Trends in Quinoxaline‐based Analogs as Protein Kinase Inhibitors: Structural Developments and SAR Insights

Cancer remains a leading cause of mortality and has been recognized as a significant global health concern. Although numerous effective anticancer agents are available; most of the current drugs lack specificity, leading to common side‐effects associated with chemotherapy. Recent research, however, offers promise for developing more targeted and safer anticancer therapies through protein kinase inhibition. Quinoxaline derivatives represent a notable class of heterocyclic compounds. The extensive spectrum of biological activities demonstrated by quinoxalines has garnered substantial research interest. Quinoxaline and its derivatives have emerged as a novel class of chemotherapeutic agents with significant activity against various tumors through protein kinase inhibition. This review aims to elucidate recent advancements in the quinoxaline derivatives targeting protein kinase along with structural developments and structure‐activity relationships associated with these compounds.

Evaluation of drug-drug interactions of a novel potent FLT3 inhibitor SKLB1028 in healthy subjects.

SKLB1028 is a novel multi-target protein kinase inhibitor under investigation for the treatment of FLT3-ITD mutated acute myeloid leukemia. Based on the preclinical characterization of SKLB1028 metabolism, three drug-drug interaction clinical studies were performed to investigate the effects of itraconazole, rifampin (CYP3A4 inhibitor and inducer, respectively), and gemfibrozil (CYP2C8 inhibitor) on the metabolism of SKLB1028. Fourteen healthy Chinese male subjects were enrolled in each study. In Study 1, subjects were administered a single dose of SKLB1028 (100 mg on days 1 and 11) and multiple doses of itraconazole (200 mg twice daily on day 8 and 200 mg once daily from days 9 to 18). Itraconazole was given with a loading dose on Day 8 and the total administration of itraconazole was 11 days. In Study 2, subjects were administered a single dose of SKLB1028 (100 mg on days 1 and 12) and multiple doses of gemfibrozil (600 mg twice daily from days 8 to 19). In Study 3, subjects were administered a single dose of SKLB1028 (150 mg on days 1 and 15) and multiple doses of rifampin (600 mg once daily from day 8 to 22). Itraconazole increased the AUC and Cmax of SKLB1028 by approximately 28% and 41%, respectively. Compared to the single drug, co-administration with gemfibrozil increased the AUC of SKLB1028 by ~26% and the Cmax by ~21%. Co-administration with rifampin reduced the AUC of SKLB1028 by ~30%, while the Cmax did not change significantly. All treatments were well tolerated in all three studies.

Childhood Langerhans cell histiocytosis hematological involvement: severity associated with BRAFV600E loads

Hematological involvement (HI) is one of the life-threatening risk organs (ROs) in Langerhans cell histiocytosis (LCH). Lahey criteria have defined HI since 1975 as hemoglobin <10 g/dL and/or platelets <100 G/L and/or leukopenia (white blood cell count <4 G/L) and/or neutrophils <1.5 G/. Among the 2313 patients <18 years old enrolled in the French National Histiocytosis Registry (1983-2023), 331 developed HI (median age at diagnosis: 1 year); median follow-up lasted 8.1 years. Bone-marrow aspirate smears and biopsies may show reactive histiocytes, hemophagocytosis or myelofibrosis but never confirm the diagnosis. Fifty-eight (17%) patients developed macrophage-activation syndrome, sometimes related to acute Epstein-Barr virus or cytomegalovirus infection, sometimes months before typical LCH manifestations appeared. Hemoglobin and platelet thresholds for initiating transfusion(s) appear to accurately distinguish 2 groups: mild HI (MHI; >7 g/dL and >20 G/L, respectively) and severe HI (SHI; ≤7 g/dL and ≤20 G/L). Each entity has different organ involvements, laboratory parameters, mutational status, blood BRAFV600E loads, drug sensitivities and outcomes (respective MHI and SHI 10-year survival rates: 98% and 73%). Since 1998, mortality first declined with combination Cladribine-cytarabine therapy, and then with mitogen-activated protein-kinase inhibitors since 2014. Forty-one (12%) patients developed neurodegenerative complications that have emerged as a risk for long-term survivors. These results suggest limiting the HI-RO definition to SHI, as it encompasses almost all medical complications of LCH. Future clinical trials might demonstrate that targeted-therapy approaches would be better adapted for these patients, while MHI can be managed with classic therapies.

Galangin Regulates Astrocyte Phenotypes to Ameliorate Cerebral Ischemia-reperfusion Injury by Inhibiting the RhoA/ROCK/LIMK Pathway.

This study aimed to explore whether Galangin (Gal) could improve cerebral Ischemia- reperfusion (I/R) injury by regulating astrocytes, and clarify its potential molecular mechanism. An I/R injury model of rats was established using the Middle Cerebral Artery Occlusion/Reperfusion (MCAO/R) method, followed by the administration of Gal (25, 50, 100 mg/kg) via gavage for 14 consecutive days. Besides, astrocytes were isolated from the rats to construct an Oxygen-Glucose Deprivation/Re-oxygenation (OGD/R) cell model, with treatments of Gal or the Ras homolog gene family member A (RhoA)/Rho-associated Coiled-coil containing protein Kinase (ROCK) inhibitor Y-27632. Subsequently, the severity of nerve injury was assessed using the modified Neurological Severity Score (mNSS) test; behavioral disorders in I/R rats were observed through the open field and ladder-climbing tests. Pathological damages and neuron survival in the peri-infarct zone were examined by hematoxylin and eosin staining and NeuN staining, respectively. Additionally, immunofluorescence staining was employed to determine astrocyte polarization and TUNEL staining was carried out to measure the level of cell apoptosis; also, western blot was performed to detect the expression of proteins related to the RhoA/ROCK/LIM domain Kinase (LIMK) pathway. Gal significantly ameliorated the neurological and motor dysfunctions caused by I/R in rats, reduced pathological damage in the peri-infarct zone, and promoted neuronal survival. Additionally, Gal increased the number of A2 astrocytes, while it decreased the number of A1 astrocytes. In vitro experiments revealed that the effect of Gal was consistent with that of Y-27632. Additionally, Gal significantly enhanced the survival of OGD/R cells, increased the number of A2 astrocytes, and inhibited the expression of proteins associated with the RhoA/ROCK pathway. Gal could reduce the level of apoptosis, promote the polarization of A2 astrocytes, and improve cerebral I/R injury, and its mechanism may be related to the inhibition of the RhoA/ROCK pathway.

Impact of Xerosis in Patients With Cancer Receiving Epidermal Growth Factor Receptor or Mitogen-Activated Protein Kinase Inhibitors: ATIXI, A Non-Interventional, Prospective, Pilot Study

Impact of Xerosis in Patients With Cancer Receiving Epidermal Growth Factor Receptor or Mitogen-Activated Protein Kinase Inhibitors: ATIXI, A Non-Interventional, Prospective, Pilot Study

Platelet Glycoprotein Ibα Cytoplasmic Tail Exacerbates Thrombosis During Bacterial Sepsis.

Septic patients, coupling severe disseminated intravascular coagulation (DIC) and thrombocytopenia, have poor prognoses and higher mortality. The platelet glycoprotein Ibα (GPIbα) is involved in thrombosis, hemostasis, and inflammation response. However, it remains unclear whether the GPIbα cytoplasmic tail regulates sepsis-mediated platelet activation and inflammation, especially in Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) infections. Using a mouse model of S. aureus-induced bacteremia, we found that both 10 amino acids of GPIbα C-terminal sequence deficiency and pharmacologic inhibition of protein kinase C (PKC) alleviated pathogenesis by diminishing platelet activation and aggregate formation. Furthermore, the GPIbα cytoplasmic tail promoted the phagocytosis of platelets by Kupffer cells in vivo. The genetically deficient GPIbα cytoplasmic tail also downregulated inflammatory cytokines and reduced liver damage, ultimately improving the survival rate of the septic mice. Our results illustrate that the platelet GPIbα cytoplasmic domain exacerbates excessive platelet activation and inflammation associated with sepsis through a PKC-dependent pathway. Thus, our findings provide insights for the development of effective therapeutic strategies using PKC inhibitor treatment against bacterial infection.

DNA-PK inhibition shows differential radiosensitization in orthotopic GBM PDX models based on DDR pathway deficits.

Glioblastoma (GBM) remains one of the most therapy-resistant malignancies with frequent local failures despite aggressive surgery, chemotherapy, and ionizing radiation (IR). Small molecule inhibitors of DNA-dependent protein kinase (DNA-PKi's) are potent radiosensitizers currently in clinical trials. Determining which patients may benefit from radiosensitization with DNA-PKi's is critical to avoid unnecessary increased risk of normal tissue toxicity. In this study we used GBM patient derived xenografts (PDXs) in orthotopic murine models to study the relationship between molecular features, pharmacokinetics, and the radiosensitizing potential of the DNA-PKi peposertib. We show that peposertib radiosensitizes established and PDX GBM lines in vitro at 300nM and above, with significant increase in radiosensitization by maintaining post-IR exposure for >12 hours. Radiosensitization by peposertib is mediated by catalytic inhibition of DNA-PK, and knock-down of DNA-PK by short hairpin RNA (shRNA) largely abolished the radiosensitizing effect. Peposertib decreased auto-phosphorylation of DNA-PKcs after IR in a dose-dependent manner with delay in resolution of γH2AX foci at 24 hours. The addition of peposertib to IR significantly increased survival in GBM120 orthotopic xenografts, but not in GBM10. There was no difference in plasma or average tumor concentrations of peposertib in the two cohorts. While the mechanism underpinning this discordant effect in vitro vs. in vivo is not clear, there was an association for greater sensitization in TP53 mutant lines. Transfection of a dominant-negative TP53 mutant in baseline TP53 wildtype GBM lines significantly delayed growth and decreased NHEJ efficiency (but not Homologous Recombination), after peposertib exposure.