Displaying publications 1 - 20 of 116 in total

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  1. Baharuddin FF, Mad Nasir N, Tejo BA, Koh SP, Ramakrishnan S, Nordin NQAA, et al.
    J Asian Nat Prod Res, 2024 May;26(5):575-582.
    PMID: 37796247 DOI: 10.1080/10286020.2023.2264784
    Tyrosinase inhibitors can reduce melanin production for skin whitening, but some existing products may harm the skin. This study discovered six compounds that inhibit tyrosinase in the mushroom Agaricus bisporus by over 50%. Compound 11 displayed strong inhibition (92.2% and 86.7%) for L-tyrosine and L-DOPA substrates, while compound 13 showed high inhibition (96.0% and 62.0%) for both substrates. Molecular docking simulations revealed compounds 11 and 13 bind at the allosteric site of the enzyme. Xanthone derivatives, based on these findings, hold potential as safe skin whitening agents and for pigmentation-related diseases in the cosmetic industry.
    Matched MeSH terms: Tyrosine/pharmacology; Tyrosine/chemistry
  2. Tablit S, Krache R, Amroune S, Jawaid M, Hachaichi A, Ismail AS, et al.
    J Mech Behav Biomed Mater, 2024 Apr;152:106438.
    PMID: 38359736 DOI: 10.1016/j.jmbbm.2024.106438
    Arundo donax L. is investigated in this study as a suitable reinforcing agent for PLA/PP waste blend 3D printing filament. To improve the compatibility of the fibre and polymer, the Arundo fibre was chemically modified using alkali and silane treatment. Untreated and treated fibres were extruded with Polymer blends before being 3D printed. Effect of chemical treatment on thermal, mechanical, and morphological properties of the composites was investigated. The tensile, Izod impact, and water absorption of the 3D printed specimens were also tested. The Alkali treated (ALK) and combination of alkali and silane treatment (SLN) composites displayed good results. Tensile strength and modulus of the materials increased, as well as their maintained stability in the Izod impact test, demonstrating that the incorporation of ArF did not result in a loss in performance. SEM examination supported these findings by confirming the creation of beneficial interfacial contacts between the matrix and fibre components, as demonstrated by the lack of void between the matrix and the fibre surface. Furthermore, the alkali treatment of the ArF resulted in a considerable reduction in water absorption inside the biocomposite, with a 64% reduction seen in ALK composite comparison to the untreated composite (Un). After the 43-day assessment period.
    Matched MeSH terms: Receptor Protein-Tyrosine Kinases
  3. Lai SK, Bakrin IH, Abd Rauf N, Abdul Raub SH
    Malays J Pathol, 2024 Apr;46(1):103-108.
    PMID: 38682850
    Spitz tumour with ALK rearrangement is a recently described entity and a rare tumour. The incidence of Spitz tumour was estimated at 3.63 per 100,000 persons in American paediatric population; while there is no data in Asian population. Here we reported a case of an eleven-year-old Asian boy who presented with a left shin nodule of two months' duration. The skin biopsy revealed a Spitz tumour with predominantly spindle cell morphology arranged in fascicles, vertically orientated nests and radial growth pattern. Junctional component, melanin pigment or Kamino bodies were not identified. Immunohistochemical study displayed homogenous cytoplasmic staining for ALK. Fluorescence in-situ hybridisation (FISH) analysis confirmed ALK rearrangement. Review of the literatures demonstrated that positive ALK immunohistochemistry may not correlate with ALK rearrangement. ALK-rearranged Spitz tumour confirmed with FISH analysis favour clinically benign behaviour despite atypical histomorphology or positive sentinel lymph node. Therefore, correlation of histomorphology, immunohistochemical stain and molecular study are important for the definitive diagnosis of this entity.
    Matched MeSH terms: Receptor Protein-Tyrosine Kinases/genetics
  4. Wan Mohamad Darani WNS, Mat Ruzlin AN, Azhar ZI, Chen XW
    Sci Rep, 2024 Mar 22;14(1):6890.
    PMID: 38519534 DOI: 10.1038/s41598-024-57593-y
    The growing Human Immunodeficiency Virus (HIV) incidences and insufficient HIV knowledge among Malaysian late adolescents necessitate immediate attention to HIV prevention via education. This study aims to develop and validate an Information-Motivation-Behavioural skills (IMB) model-based education kit for adolescents, PREM-Kit, to educate on HIV prevention among Malaysian late adolescents. Utilizing the Analysis, Design, Development, Implementation, and Evaluation model, we conducted the study in three phases: needs assessment, development of PREM-Kit, and validation of PREM-Kit by applying the IMB model to map the PREM-Kit's contents. PREM-Kit, developed in Malay language, consisted of an infographic flip chart and videos. Five multi-disciplinary experts validated the PREM-Kit using the content validity index (CVI), and 13 end-users validated the PREM-Kit using the Malay version of the Patient Education Materials Assessment Tool for Printable and Audiovisual Materials. The infographic flip chart comprised three modules covering 15 topics, and an animated video accompanied each module. PREM-Kit achieved CVI scores of 1.0 and median scores of over 80% for understandability and actionability. Overall, the newly developed IMB model-based HIV education kit has good content validity, is simple to comprehend and apply, and is ready for testing its effectiveness in improving adolescents' knowledge, attitudes, and practices for HIV prevention.
    Matched MeSH terms: Receptor Protein-Tyrosine Kinases
  5. Yahya TSANT, Azmi NC, Yee FS, Chyang PJ, Ting NS, Seng TC
    Int J Med Mushrooms, 2024;26(3):55-66.
    PMID: 38505903 DOI: 10.1615/IntJMedMushrooms.2024052325
    Leukemia can be a result of genetic changes associated with protein tyrosine kinase activity such as in MPL W515L and BCR/ABL genes. However, the current conventional treatment of leukemia produces severe side effects that urge the approach to use natural products. A medicinal mushroom, Lignosus rhinocerus shows potential as an anti-cancer treatment. To investigate the efficacy and mechanism of action of the L. rhinocerus cultivar (TM02®) extract on leukemogenic tyrosine kinase cell lines, a cold-water extract (CWE) was produced by using TM02® sclerotia powder at 4°C. The carbohydrate and protein contents were found to be 77.24% and 1.75% respectively. In comparison to the normal Ba/F3 cell, the CWE TM02® shows significant effects on exhibiting proliferation of Ba/F3 expressed MPL W515L and BCR/ABL, possibly due to the presence of phenolic compounds and antioxidant properties of TM02®, which contribute to act on various signaling pathways, and the reported apoptotic activity of CWE TM02®. In contrast, CWE TM02® significantly exhibited high scavenging activity of both Ba/F3 expressed MPL W515L and BCR/ABL. At concentrations of 125 μg/mL and 500 μg/mL of CWE TM02® decreased 49.5% and 67.5% of cell migration activity of Ba/F3 expressed MPL W515L and BCR/ABL respectively. Therefore, we postulate that CWE TM02® has the capability to mediate the migration route of the leukemogenic tyrosine kinase cell lines.
    Matched MeSH terms: Protein-Tyrosine Kinases
  6. Faiz M, Rashid F
    Malays J Pathol, 2023 Aug;45(2):205-214.
    PMID: 37658530
    INTRODUCTION: Mutations in FLT3 are the most commonly reported genetic changes in AML patients. These mutations are normally identified in approximately one third of newly diagnosed patients and are reported to have prognostic significance.

    MATERIALS AND METHODS: Peripheral blood samples was collected from 63 AML patients to study their morphological, cytogenetic and molecular features. PCR was used to determine the prevalence of FLT3 mutations; internal tandem duplication (ITD) and tyrosine kinase domain (TKD) in AML patients.

    RESULTS: Among 63 AML patients, 42 were males and 21 were females with male to female ratio 2:1 with median age of 32 years. AML-M2 was the predominant French-American-British (FAB) subtype (42%) followed by M4 (27%), M3 (8%), M1 (8%), M0 (8%) and M5 (7%) respectively. Cytogenetic analysis of 60 patients showed 58% as cytogenetically normal (CN) whereas 42% had aberrant karyotype.The most frequent aberrations were trisomy8, t(8;21), t(15;17) (8.3%) each, inversion16 (5%), and different deletions (12%) respectively. FAB-M4 subtype showed most of the chromosomal anomalies. Among 63 AML patients, 22% showed FLT3/ITD while 6.4% had D835 mutation after molecular analysis. FLT3 mutations were found in most of the FAB subtypes and cytogenetic groups. FLT3/ITD mutations were more common in patients with normal karyotype (26%) and usually present with hyperleukocytosis but association between two was not significant.

    CONCLUSION: The cytogenetic data of adult AML from Pakistan showed presence of favourable prognostic karyotype with comparable prevalence as reported in international data. Moreover, FLT3/ITD mutations are commonly found in our patients as determined by molecular analysis. Therefore, inclusion of this unfavourable prognostic marker should be routine in molecular diagnostic testing of AML.

    Matched MeSH terms: fms-Like Tyrosine Kinase 3/genetics
  7. Azlan A, Khor KZ, Rajasegaran Y, Rosli AA, Said MSM, Yusoff NM, et al.
    Med Oncol, 2023 Jun 21;40(7):208.
    PMID: 37341821 DOI: 10.1007/s12032-023-02075-w
    Reactive oxygen species (ROS) homeostasis is crucial for leukaemogenesisand deregulation would hamper leukaemic progression. Although the regulatory effects of RUNX1/ETO has been extensively studied, its underlying molecular mechanims in ROS production in t(8,21) AML is yet to be fully elucidated. Here, we report that RUNX1/ETO could directly control FLT3 by occupying several DNA elements on FLT3 locus. The possible hijacking mechanism by RUNX1/ETO over FLT3 mediated ROS modulation in AML t(8;21) was made apparent when suppression of RUNX1/ETO led to decrement in ROS levels and the direct oxidative marker FOXO3 but not in FLT3 and RAC1 suppressed t(8,21) AML cell line Furthermore, nuclear import of RUNX1/ETO was aberrated following RUNX1/ETO and RAC1 suppression suggesting association in ROS control. A different picture was depicted in non t(8;21) cells where suppression of RAC1 and FLT3 led to decreased levels of FOXO3a and ROS. Results alltogether indicate a possible dysregulation of ROS levels by RUNX1/ETO in t(8,21) AML.
    Matched MeSH terms: fms-Like Tyrosine Kinase 3/genetics; fms-Like Tyrosine Kinase 3/metabolism
  8. Filippova TA, Masamrekh RA, Shumyantseva VV, Latsis IA, Farafonova TE, Ilina IY, et al.
    Talanta, 2023 May 15;257:124341.
    PMID: 36821964 DOI: 10.1016/j.talanta.2023.124341
    In this work, we proposed a biosensor for trypsin proteolytic activity assay using immobilization of model peptides on screen-printed electrodes (SPE) modified with gold nanoparticles (AuNPs) prepared by electrosynthetic method. Sensing of proteolytic activity was based on electrochemical oxidation of tyrosine residues of peptides. We designed peptides containing N-terminal cysteine residue for immobilization on an SPE, modified with gold nanoparticles, trypsin-specific cleavage site and tyrosine residue as a redox label. The peptides were immobilized on SPE by formation of chemical bonds between mercapto groups of the N-terminal cysteine residues and AuNPs. After the incubation with trypsin, time-dependent cleavage of the immobilized peptides was observed by decline in tyrosine electrochemical oxidation signal. The kinetic parameters of trypsin, such as the catalytic constant (kcat), the Michaelis constant (KM) and the catalytic efficiency (kcat/KM), toward the CGGGRYR peptide were determined as 0.33 ± 0.01 min-1, 198 ± 24 nM and 0.0016 min-1 nM-1, respectively. Using the developed biosensor, we demonstrated the possibility of analysis of trypsin specificity toward the peptides with amino acid residues disrupting proteolysis. Further, we designed the peptides with proline or glutamic acid residues after the cleavage site (CGGRPYR and CGGREYR), and trypsin had reduced activity toward both of them according to the existing knowledge of the enzyme specificity. The developed biosensor system allows one to perform a comparative analysis of the protease steady-state kinetic parameters and specificity toward model peptides with different amino acid sequences.
    Matched MeSH terms: Tyrosine
  9. Cho BC, Kim DW, Batra U, Park K, Kim SW, Yang CT, et al.
    Cancer Res Treat, 2023 Jan;55(1):83-93.
    PMID: 35344649 DOI: 10.4143/crt.2021.1571
    PURPOSE: Previous report from the ASCEND-8 trial showed consistent efficacy with less gastrointestinal (GI) toxicity in patients with anaplastic lymphoma kinase-rearranged (ALK+) advanced/metastatic non-small cell lung cancer (NSCLC) treated with ceritinib 450-mg with food compared with 750-mg fasted. In this subgroup analysis, we report outcomes in Asian patients of the ASCEND-8 trial.

    MATERIALS AND METHODS: Key efficacy endpoints were blinded independent review committee (BIRC)-assessed overall response rate (ORR) and duration of response (DOR) evaluated per Response Evaluation Criteria in Solid Tumors v1.1. Other efficacy endpoints were investigator-assessed ORR and DOR; BIRC- and investigator-assessed progression-free survival (PFS) and disease control rate; overall survival (OS). Safety was evaluated by frequency and severity of adverse events.

    RESULTS: At final data cutoff (6 March 2020), 198 treatment-naïve patients were included in efficacy analysis, of which 74 (37%) comprised the Asian subset; 450-mg fed (n=29), 600-mg fed (n=19), and 750-mg fasted (n=26). Baseline characteristics were mostly comparable across study arms. At baseline, more patients in 450-mg fed arm (44.8%) had brain metastases than in 750-mg fasted arm (26.9%). Per BIRC, patients in the 450-mg fed arm had a numerically higher ORR, 24-month DOR rate and 24-month PFS rate than the 750-mg fasted arm. The 36-month OS rate was 93.1% in 450-mg fed arm and 70.9% in 750-mg fasted arm. Any-grade GI toxicity occurred in 82.8% and 96.2% of patients in the 450-mg fed and 750-mg fasted arms, respectively.

    CONCLUSION: Asian patients with ALK+ advanced/metastatic NSCLC treated with ceritinib 450-mg fed showed numerically higher efficacy and lower GI toxicity than 750-mg fasted patients.

    Matched MeSH terms: Receptor Protein-Tyrosine Kinases
  10. Prasher P, Sharma M, Chan Y, Singh SK, Anand K, Dureja H, et al.
    Curr Med Chem, 2023;30(13):1529-1567.
    PMID: 34766883 DOI: 10.2174/0929867328666211111161811
    Protein kinases modulate the structure and function of proteins by adding phosphate groups to threonine, tyrosine, and serine residues. The phosphorylation process mediated by the kinases regulates several physiological processes, while their overexpression results in the development of chronic diseases, including cancer. Targeting of receptor tyrosine kinase pathways results in the inhibition of angiogenesis and cell proliferation that validates kinases as a key target in the management of aggressive cancers. As such, the identification of protein kinase inhibitors revolutionized the contemporary anticancer therapy by inducing a paradigm shift in the management of disease pathogenesis. Contemporary drug design programs focus on a broad range of kinase targets for the development of novel pharmacophores to manage the overexpression of kinases and their pathophysiology in cancer pathogenesis. In this review, we present the emerging trends in the development of rationally designed molecular inhibitors of kinases over the last five years (2016-2021) and their incipient role in the development of impending anticancer pharmaceuticals.
    Matched MeSH terms: Receptor Protein-Tyrosine Kinases
  11. Chear CT, Ismail IH, Chan KC, Noh LM, Kassim A, Latiff AHA, et al.
    Front Immunol, 2023;14:1252765.
    PMID: 37809070 DOI: 10.3389/fimmu.2023.1252765
    BACKGROUND: Bruton's tyrosine kinase (BTK) is a cytoplasmic protein involved in the B cell development. X-linked agammaglobulinemia (XLA) is caused by mutation in the BTK gene, which results in very low or absent B cells. Affected males have markedly reduced immunoglobulin levels, which render them susceptible to recurrent and severe bacterial infections. Methods: Patients suspected with X-linked agammaglobulinemia were enrolled during the period of 2010-2018. Clinical summary, and immunological profiles of these patients were recorded. Peripheral blood samples were collected for monocyte BTK protein expression detection and BTK genetic analysis. The medical records between January 2020 and June 2023 were reviewed to investigate COVID-19 in XLA.

    RESULTS: Twenty-two patients (from 16 unrelated families) were molecularly diagnosed as XLA. Genetic testing revealed fifteen distinct mutations, including four splicing mutations, four missense mutations, three nonsense mutations, three short deletions, and one large indel mutation. These mutations scattered throughout the BTK gene and mostly affected the kinase domain. All mutations including five novel mutations were predicted to be pathogenic or deleterious by in silico prediction tools. Genetic testing confirmed that eleven mothers and seven sisters were carriers for the disease, while three mutations were de novo. Flow cytometric analysis showed that thirteen patients had minimal BTK expression (0-15%) while eight patients had reduced BTK expression (16-64%). One patient was not tested for monocyte BTK expression due to insufficient sample. Pneumonia (n=13) was the most common manifestation, while Pseudomonas aeruginosa was the most frequently isolated pathogen from the patients (n=4). Mild or asymptomatic COVID-19 was reported in four patients.

    CONCLUSION: This report provides the first overview of demographic, clinical, immunological and genetic data of XLA in Malaysia. The combination of flow cytometric assessment and BTK genetic analysis provides a definitive diagnosis for XLA patients, especially with atypical clinical presentation. In addition, it may also allow carrier detection and assist in genetic counselling and prenatal diagnosis.

    Matched MeSH terms: Protein-Tyrosine Kinases/genetics
  12. Abdullah MN, Ali Y, Abd Hamid S
    Chem Biol Drug Des, 2022 Dec;100(6):921-934.
    PMID: 34651438 DOI: 10.1111/cbdd.13974
    Tyrosine kinase overexpression could result in an unfavourable consequence of cancer progression in the body. A number of kinase inhibitor drugs targeting various cancer-related protein kinases have been developed and proven successful in clinical therapy. Benzimidazole is one of the most studied scaffolds in the search for effective anticancer drugs. The association of various functional groups and the structural design of the compounds may influence the binding towards the receptor. Despite numerous publications on the design, synthesis and biological assays of benzimidazole derivatives, their inhibitory activities against epidermal growth factor receptor (EGFR), a receptor tyrosine kinase (RTK), have not been specifically analysed. This review covers recent research reports on the anticancer activity of benzimidazole derivatives focusing on EGFR expression cell lines, based on their structure-activity relationship study. We believe it would aid researchers to envision the challenges and explore benzimidazole's potentials as tyrosine kinase inhibitors.
    Matched MeSH terms: Protein-Tyrosine Kinases
  13. Vijayanathan Y, Hamzah NM, Lim SM, Lim FT, Tan MP, Majeed ABA, et al.
    Brain Res Bull, 2022 Nov;190:218-233.
    PMID: 36228872 DOI: 10.1016/j.brainresbull.2022.10.001
    In order to understand the biological processes underlying dopaminergic neurons (DpN) regeneration in a 6-hydroxydopamine(6-OHDA)-induced adult zebrafish-based Parkinson's disease model, this study investigated the specific phases of neuroregeneration in a time-based manner. Bromodeoxyuridine (BrdU) was administered 24 h before the harvest of brain tissues at day three, five, seven, nine, 12 and 14 postlesion. Potential migration of proliferative cells was tracked over 14 days postlesion through double-pulse tracking [BrdU and 5-ethynyl-2'-deoxyuridine (EdU)] of cells and immunohistostaining of astrocytes [glial fibrillary acidic protein (GFAP)]. Gene expression of foxa2 and nurr1 (nr4a2a) at day three, nine, 14, 18, 22 and 30 postlesion was quantified using qPCR. Protein expression of foxa2 at day three, seven, 14 and 22 postlesion was validated using the western blot technique. Double labelling [EdU and tyrosine hydroxylase (TH)] of proliferative cells was performed to ascertain their fate after the neuroregeneration processes. It was found that whilst cell proliferation remained unchanged in the area of substantial DpN loss, the ventral diencephalon (vDn), there was a transient increase of cell proliferation in the olfactory bulb (OB) and telencephalon (Tel) seven days postlesion. BrdU-immunoreactive (ir)/ EdU-ir cells and activated astrocytes were later found to be significantly increased in the vDn and its nearby area (Tel) 14 days postlesion. There was a significant but transient downregulation of foxa2 at day three and nine postlesion, and nr4a2a at day three, nine and 14 postlesion. The expression of both genes remained unchanged in the OB and Tel. There was a transient downregulation of foxa2 protein expression at day three and seven postlesion. The significant increase of EdU-ir/ TH-ir cells in the vDn 30 days postlesion indicates maturation of proliferative cells (formed between day five-seven postlesion) into DpN. The present findings warrant future investigation of critical factors that govern the distinctive phases of DpN regeneration.
    Matched MeSH terms: Tyrosine 3-Monooxygenase/metabolism
  14. Edwards MJ, Wilson GC, Keitsch S, Soddemann M, Wilker B, Müller CP, et al.
    J Neurochem, 2022 Nov;163(4):357-369.
    PMID: 36227646 DOI: 10.1111/jnc.15708
    Major depressive disorder (MDD) is a severe disease of unknown pathogenesis with a lifetime prevalence of ~10%. Therapy requires prolonged treatment that often fails. We have previously demonstrated that ceramide levels in the blood plasma of patients and in mice with experimental MDD are increased. Neutralization of blood plasma ceramide prevented experimental MDD in mice. Mechanistically, we demonstrated that blood plasma ceramide accumulated in endothelial cells of the hippocampus, inhibited phospholipase D (PLD) and thereby decreased phosphatidic acid in the hippocampus. Here, we demonstrate that phosphatidic acid binds to and controls the activity of phosphotyrosine phosphatase (PTP1B) in the hippocampus and thus determines tyrosine phosphorylation of a variety of cellular proteins including TrkB. Injection of PLD, phosphatidic acid, or inhibition of PTP1B abrogated MDD and normalized cellular tyrosine phosphorylation, including phosphorylation of TrkB and neurogenesis in the hippocampus. Most importantly, these treatments also rapidly normalized behavior of mice with experimental MDD. Since phosphatidic acid binds to and inhibits PTP1B, the lack of phosphatidic acid results in increased activity of PTP1B and thereby in reduced tyrosine phosphorylation of TrkB and other cellular proteins. Thus, our data indicate a novel pathogenetic mechanism of and a rapidly acting targeted treatment for MDD.
    Matched MeSH terms: Tyrosine/metabolism
  15. Soo R, Mery L, Bardot A, Kanesvaran R, Keong TC, Pongnikorn D, et al.
    ESMO Open, 2022 Oct;7(5):100560.
    PMID: 35988454 DOI: 10.1016/j.esmoop.2022.100560
    BACKGROUND: Lung cancer is the second most common cancer and leading cause of cancer mortality worldwide. Recent advances in molecular testing and targeted therapy have improved survival among patients with metastatic non-small-cell lung cancer (NSCLC). We sought to quantify and describe molecular testing among metastatic non-squamous NSCLC cases in selected Southeast Asian countries and describe first-line therapy chosen.

    PATIENTS AND METHODS: A retrospective study was conducted based on incident lung cancer cases diagnosed between 2017 and 2019 in Lampang (Thailand), Penang (Malaysia), Singapore and Yogyakarta (Indonesia). Cases (n = 3413) were defined using the International Classification of Diseases for Oncology third edition. In Singapore, a clinical series obtained from the National Cancer Centre was used to identify patients, while corresponding population-based cancer registries were used elsewhere. Tumor and clinical information were abstracted by chart review according to a predefined study protocol. Molecular testing of epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) gene rearrangement, ROS1 gene rearrangement and BRAF V600 mutation was recorded.

    RESULTS: Among 2962 cases with a specified pathological diagnosis (86.8%), most patients had non-squamous NSCLC (75.8%). For cases with staging information (92.1%), the majority presented with metastatic disease (71.3%). Overall, molecular testing rates in the 1528 patients with stage IV non-squamous NSCLC were 67.0% for EGFR, 42.3% for ALK, 39.1% for ROS1, 7.8% for BRAF and 36.1% for PD-L1. Among these patients, first-line systemic treatment included chemotherapy (25.9%), targeted therapy (35.6%) and immunotherapy (5.9%), with 31% of patients having no record of antitumor treatment. Molecular testing and the proportion of patients receiving treatment were highly heterogenous between the regions.

    CONCLUSIONS: This first analysis of data from a clinically annotated registry for lung cancer from four settings in Southeast Asia has demonstrated the feasibility of integrating clinical data within population-based cancer registries. Our study results identify areas where further development could improve patient access to optimal treatment.

    Matched MeSH terms: Protein-Tyrosine Kinases/genetics; Protein-Tyrosine Kinases/therapeutic use
  16. Kollu U, Avula VKR, Vallela S, Pasupuleti VR, Zyryanov GV, Neelam YS, et al.
    Bioorg Chem, 2021 06;111:104837.
    PMID: 33812281 DOI: 10.1016/j.bioorg.2021.104837
    A new series of urea/thiourea derivatives have been efficiently synthesized from the reaction of L-3-hydroxytyrosine with selective isocyanates/isothiocyanates and characterized by Infra-red, proton & carbon-13 nuclear magnetic resonance spectral and mass spectrometry studies. All the synthesized compounds have been screened for their antioxidant activity by 1,1-diphenyl1-2-picrylhydrazyl radical assay, ferric reducing antioxidant power assay and also studied their molecular docking interaction profiles against 1N8Q and 3NRZ enzymatic proteins. The in vitro antioxidant activity has further supported by quantitative structure activity relationship, absorption, distribution, metabolism, and excretion & toxicity studies, bioactivity studies & enzyme inhibition assay and identified that they were potentially bound to ASP490 & ASP361 aminoacid residue in chain A of 1N8Q protein and GLN1194 aminoacid residue in chain L of 3NRZ protein and are responsible for potential antioxidant activity. It is proved that urea derivatives linked with 4-fluoro & 4-nitro and thiourea derivatives linked with 3-chloro & 4-fluoro have exhibited promising antioxidant activity. In eventual synthesized compounds have been identified as potential blood-brain barrier penetrable compounds and proficient central nervous system active neuro-protective antioxidant agents as they have envisaged as easily penetrable to blood-brain barrier thresholds, a neuroprotective property.
    Matched MeSH terms: Tyrosine/chemical synthesis; Tyrosine/pharmacology*; Tyrosine/chemistry
  17. Liew K, Yu GQS, Wei Pua LJ, Wong LZ, Tham SY, Hii LW, et al.
    Cancer Lett, 2021 Apr 28;504:81-90.
    PMID: 33587980 DOI: 10.1016/j.canlet.2021.02.006
    Despite recent in advances in the management of nasopharyngeal carcinoma (NPC), development of targeted therapy remains challenging particularly in patients with recurrent or metastatic disease. To search for clinically relevant targets for the treatment of NPC, we carried out parallel genome-wide functional screens to identified essential genes that are required for NPC cells proliferation and cisplatin resistance. We identified lymphocyte-specific protein tyrosine kinase (LCK) as a key vulnerability of both proliferation and cisplatin resistance. Depletion of endogenous LCK or treatment of cells with LCK inhibitor induced tumor-specific cell death and synergized cisplatin sensitivity in EBV-positive C666-1 and EBV-negative SUNE1 cells. Further analyses demonstrated that LCK is regulating the proliferation and cisplatin resistance through activation of signal transducer and activator of transcription 5 (STAT5). Taken together, our study provides a molecular basis for targeting LCK and STAT5 signaling as potential druggable targets for the management of NPC.
    Matched MeSH terms: Protein-Tyrosine Kinases/genetics*
  18. Angelopoulou E, Paudel YN, Julian T, Shaikh MF, Piperi C
    Mol Neurobiol, 2021 Apr;58(4):1372-1391.
    PMID: 33175322 DOI: 10.1007/s12035-020-02201-z
    The exact etiology of Parkinson's disease (PD) remains obscure, although many cellular mechanisms including α-synuclein aggregation, oxidative damage, excessive neuroinflammation, and dopaminergic neuronal apoptosis are implicated in its pathogenesis. There is still no disease-modifying treatment for PD and the gold standard therapy, chronic use of levodopa is usually accompanied by severe side effects, mainly levodopa-induced dyskinesia (LID). Hence, the elucidation of the precise underlying molecular mechanisms is of paramount importance. Fyn is a tyrosine phospho-transferase of the Src family nonreceptor kinases that is highly implicated in immune regulation, cell proliferation and normal brain development. Accumulating preclinical evidence highlights the emerging role of Fyn in key aspects of PD and LID pathogenesis: it may regulate α-synuclein phosphorylation, oxidative stress-induced dopaminergic neuronal death, enhanced neuroinflammation and glutamate excitotoxicity by mediating key signaling pathways, such as BDNF/TrkB, PKCδ, MAPK, AMPK, NF-κB, Nrf2, and NMDAR axes. These findings suggest that therapeutic targeting of Fyn or Fyn-related pathways may represent a novel approach in PD treatment. Saracatinib, a nonselective Fyn inhibitor, has already been tested in clinical trials for Alzheimer's disease, and novel selective Fyn inhibitors are under investigation. In this comprehensive review, we discuss recent evidence on the role of Fyn in the pathogenesis of PD and LID and provide insights on additional Fyn-related molecular mechanisms to be explored in PD and LID pathology that could aid in the development of future Fyn-targeted therapeutic approaches.
    Matched MeSH terms: Tyrosine
  19. Yap PG, Gan CY
    Foods, 2021 Mar 22;10(3).
    PMID: 33810046 DOI: 10.3390/foods10030675
    Nature-derived tyrosinase inhibitors are of great industrial interest. Three monophenolase inhibitor peptides (MIPs) and three diphenolase inhibitor peptides (DIPs) from a previous study were investigated for their in vitro tyrosinase inhibitory effects, mode of inhibition, copper-chelating activity, sun protection factor (SPF) and antioxidant activities. DIP1 was found to be the most potent tyrosinase inhibitor (IC50 = 3.04 ± 0.39 mM), which could be due to the binding interactions between its aromatic amino acid residues (Y2 and D7) with tyrosinase hotspots (H85, V248, H258, H263, F264, R268, V283 and E322) and its ability to chelate copper ion within the substrate-binding pocket. The conjugated planar rings of tyrosine and tryptophan may interact with histidine within the active site to provide stability upon enzyme-peptide binding. This postulation was later confirmed as the Lineweaver-Burk analysis had identified DIP1 as a competitive inhibitor and DIP1 also showed 36.27 ± 1.17% of copper chelating activity. In addition, DIP1 provided the highest SPF value (11.9 ± 0.04) as well as ferric reducing antioxidant power (FRAP) (5.09 ± 0.13 mM FeSO4), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) (11.34 ± 0.90%) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (29.14 ± 1.36%) free radical scavenging activities compared to other peptides. These results demonstrated that DIP1 could be a multifunctional anti-tyrosinase agent with pharmaceutical and cosmeceutical applications.
    Matched MeSH terms: Tyrosine
  20. Almajali B, Al-Jamal HAN, Wan Taib WR, Ismail I, Johan MF, Doolaanea AA, et al.
    Asian Pac J Cancer Prev, 2021 Mar 01;22(3):879-885.
    PMID: 33773553 DOI: 10.31557/APJCP.2021.22.3.879
    OBJECTIVE: The natural compound, thymoquinone (TQ) has demonstrated potential anticancer properties in inhibiting cell proliferation and promoting apoptosis in myeloid leukemia cells, breast cancer cells, and others. However, the effect mechanism of TQ on AML cells still not fully understood. In this study, the authors examined the effects of TQ on the expression of JAK/STAT-negative regulator genes SOCS-1, SOCS-3, and SHP-1, and their consequences on cell proliferation and apoptosis in HL60 leukemia cells.

    METHODS: MTT and trypan blue exclusion tests were conducted to determine the 50% inhibitory concentration (IC50) and cell proliferation. FITC Annexin and Guava® reagent were used to study the cell apoptosis and examine the cell cycle phases, respectively. The expression of JAK/STAT-negative regulator genes, SOCS-1, SOCS-3, and SHP-1, was investigated using reverse transcriptase- quantitative PCR (RT-qPCR).

    RESULTS: TQ demonstrated a potential inhibition of HL60 cell proliferation and a significant increase in apoptotic cells in dose and time-dependent manner. TQ significantly induced cycle arrest at G0-G1 phase (P < 0.001) and enhanced the re-expression of JAK/STAT-negative regulator genes.

    CONCLUSION: TQ potentially inhibited HL60 cell proliferation and significantly increased apoptosis with re-expression of JAK/STAT-negative regulator genes suggesting that TQ could be a new therapeutic candidate for leukemia therapy.
    .

    Matched MeSH terms: Protein Tyrosine Phosphatase, Non-Receptor Type 6/drug effects*; Protein Tyrosine Phosphatase, Non-Receptor Type 6/genetics
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