ABNORMAL PROTEIN TYROSINE KINASES ASSOCIATED WITH HUMAN HAEMATOLOGICAL MALIGNANCIES

Objective: To survey the role of protein tyrosine kinases (PTKs) in the pathogenesis of several hematopoietic malignancies. Methods: By reviewing the published laboratory and clinical studies on PTK-related oncoproteins and their causative role in some leukemias and lymphomas. Results: Protein tyrosine kinases are key participants in signal transduction pathways that regulate cellular growth, activation and differentiations. Aberrant PTK activity resulting from gene mutation (often accompanying chromosome translocation) plays an etiologic role in several clonal hematopoietic malignancies. For example, the PTK product of the BCR-ABL fusion gene resulting from the t (9; 22) translocation exhibits several fold higher tyrosine kinase activity than the product of the ABL gene. Evidence suggests that the BCR-ABL oncoprotein alone is sufficient to case chronic myelogenous leukemia (CML) and other Ph positive acute leukemia. PTK over-activity resulting from chromosomal translocations creating TEL-ABL, TEL-JAK2 and TEL-PDGFRβ fusion proteins plays an important role in the pathogenesis of other types of leukemia. Another example occurs in anaplastic large cell lymphoma (ALCL). Experimental and clinical evidences indicate that translocations involving ALK gene on chromosome 2p23, most commonly resulting in an NPM-ALK fusion oncogene, result in constitutive activation of ALK and cause ALCL. This group of lymphomas is now named ALK positive lymphoma or ALKoma. Conclusion: Genetic lesions creating aberrant fusion proteins that result in excessive PTK activity are increasingly being recognized as central to the pathogenesis of hemotopoietic malignancies. These chimeric PTK molecules represent attractive disease-specific targets against which new classes therapeutic agents are being developed.

Modulatory Effect of Rg_1 on the Activity of ProteinTyrosine Kinase of Lymphocytes in the Elderly

The effect of Rg1,a saponin extracted froin Panax ginseng, on the phenotype,receptor and the activity of protein tyrosine kinase (PTK) of lymphocytes isolated from 7 healthy oldpersons were studied. The CD25, CD45RA and CD45RO phenotypes of lymphocytes were 4eter-mined by indirect immunofluorescence technique. The percentage of CD25, CD45RA and CD45ROpositive lymphocytes was 38.3%±17.3%, 46.0% 15.1%, and 52.6%±14.1% respectively after incu-bation with PHA (5 μ±/ml) for 72 hours. However, there were 58.0%±12.5%, CD25, 64.1% ± 12.4%,CD45RA, and 74.0%±8.0%, CD45RO positive cells in the presence of Rg, ( 1μg/ml) along with PHA(5 μg/ml) over the sanie period of incubation. A significant increase was induced by Rgi (P<0.05).The activities of PTK in the cytoplasm and membrane of lymphocytes were measured by ELISAmcthod after incubation with PHA or PHA+Rg1. The absorbance value of PTK activity in cytoplasmafter 72 hr incubation was 0. 120±0.020 in PHA group, but 0. 1 38±0.015 in PHA+Rg1 group. In thelymphocyte membrane, it was 0.374± 0.060 in PHA group and 0.403 ± 0.008 in PHA+Rg1 group(P<0.001). These results showed that Rgi significantly arid simultaneously increased both the PT Kactivity and the expression of phenotype of lymphocytes.

Role of protein tyrosine kinase in IL-1β induced activation of mitogen- activated protein kinase in fibroblast-like synoviocytes of rheumatoid arthritis

Obejctives To study mitogen activated protein kinase (MAPKs) activation in fibroblast like synoviocytes (FLS) of rheumatoid arthritis (RA) under the stimulation of IL 1β, and to elucidate the role of protein tyrosine kinase (PTK) in the activation of MAPKs Methods Primary cultures of RA FLS were used Western blot was applied to examine transient changes in protein tyrosine phosphorylation status and MAPKs activation in RA FLS stimulated with IL 1β at various doses, and over different periods Genistein, the specific PTK inhibitor, was used to evaluate the inhibitory role in activation of MAPKs by IL 1β Results IL 1β transiently increased protein tyrosine phosphorylation, and activated the MAPKs cascades (mainly ERK 2, JNK 2 and P 38 ) in RA FLS There was no obvious difference in MAPKs activation among different doses of IL 1β (1?IU/ml,10?IU/ml, 100?IU/ml), but the peak activation of ERK 2, JNK 2 and P 38 took place at 5?min, 15?min and 1?min, respectively, after stimulation with IL 1β The activation of ERK 2 was inhibited by genistein, but the inhibitory role on that of JNK and P 38 was relatively weak Conclusions During signal transduction of IL 1β in RA FLS, tyrosine phosphorylation was increased transiently, the MAPKs cascade was activated in a few minutes, and there was heterogenicity in the activation among three subfamily members PTK had a role in the activation of ERK, but had weak effects on that of JNK and P 38

EFFECT OF ACTIVE COMPOUNDS ISOLATED FROM PTERIS SEMIPINNATA L ON DNA TOPOISOMERASES AND TYROSINE PROTEIN KINASE AND EXPRESSION OF C-MYC IN LUNG ADENOCARCINOMA CELLS

Objective: To study the effect of active compound 6F and A from Pteris semipinnata L.(PsL) on the activities of DNA topoisomerase (TOPO) I and II, activities of cytosolic and membrane TPK, and expression of oncogene c-myc in lung adenocarcinoma cells. Methods: The effect of compound 6F and A on activities of cytosolic and membrane TPK was measured by scintillation counting; the effect of compound A on expression of oncogene c-myc was determined by flow cytometry indirect fluorimetry. Results: compound 6F and A could inhibit the activities of TOPO I, and they strongly inhibited the TOPO II in 0.01 mg/L and 10.0 mg/L respectively. Compound A slightly inhibited the activities of membrane TPK, but not the cytosolic one. Compound A could inhibit the expression of oncogene c-myc. Conclusion: Topoisomerases are target of compound 6F and A. Compound A could slightly inhibit the activities of TPK, and showed an inhibitory effect on the expression of oncogene c-myc.

Sunitinib-induced hyperammonemic encephalopathy in metastatic gastrointestinal stromal tumors:A case report

BACKGROUND Sunitinib,a multi-targeted tyrosine kinase inhibitor(TKI),has been approved for the salvage treatment of gastrointestinal stromal tumors(GIST).Hyperammonemic encephalopathy is a rare but severe complication of sunitinib use.Here,we present the case of a 66-year-old male with metastatic GIST without underlying liver cirrhosis who developed sunitinib-induced hyperammonemic encephalopathy.CASE SUMMARY A 66-year-old male with metastatic GIST was admitted because of reduced consciousness.Imatinib was administered as the first-line systemic therapy.He experienced repeated episodes of peritonitis due to tumor perforation,and surgery was performed.Progressive disease was confirmed based on increased liver metastasis,and sunitinib was initiated as a salvage treatment.However,23 d after the third course of sunitinib,he presented to the emergency room with an episode of altered consciousness and behavioral changes.Based on the patient clinical history and examination findings,sunitinib-induced encephalopathy was suspected.Sunitinib was discontinued,and the patient was treated for hyperammonemia.The patient had a normal level of consciousness four days later,and the serum ammonia level gradually decreased.No further neurological symptoms were reported in subsequent follow-ups.CONCLUSION TKI-induced hyperammonemic encephalopathy is potentially life-threatening.Patients receiving TKIs experiencing adverse reactions should undergo systemic evaluation and prompt treatment.

Effects of laser photocoagulation on serum angiopoietin-1, angiopoietin-2, angiopoietin-1/angiopoietin-2 ratio, and soluble angiopoietin receptor Tie-2 levels in type 2 diabetic patients with proliferative diabetic retinopathy

·AIM: To determine the effects of laser photocoagulation on serum levels of angiopoietin-1(Ang-1),angiopoietin-2(Ang-2), soluble angiopoietin receptor Tie-2(Tie-2), Ang-1/Ang-2 ratio and vascular endothelial growth factor(VEGF) in patients with type 2diabetes mellitus(T2DM) and proliferative diabetic retinopathy(PDR). We also explored the role of the Ang/Tie system in PDR.·METHODS:Totally 160patientswithT2 DM, including50 patients with non-diabetic retinopathy(NDR), 58 patients with non-proliferative diabetic retinopathy(NPDR), and52 patients with PDR were enrolled in this study. Serum Ang-1, Ang-2, Tie-2 receptor and VEGF levels were measured using enzyme-linked immunosorbent assays for all patients and were repeated in 26 patients who underwent laser photocoagulation two months after the procedure.·RESULTS:ThemedianlevelsofAng-2andVEGFinserum were significantly higher in the NPDR group(4.23 ng/mL and 303.2 pg/mL, respectively) compared to the NDR group(2.67 ng/mL and 159.8 pg/mL, respectively, P 【0.01), with the highest level in the PDR group(6.26 ng/mL and531.2 pg/mL, respectively, P 【0.01). The median level of Ang-1 was significantly higher in the NPDR group(10.77ng/mL) compared to the NDR group(9.31 ng/mL) and the PDR groups(9.54 ng/mL)(P 【0.05), while no difference was observed between the PDR and NDR groups. Ang-1/Ang-2 ratio of PDR group was lowest in three groups(1.49 vs 2.69 and 2.90, both P 【0.01). The median level of Tie-2was not significantly different among three groups(P 】0.05).Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups(both P 【0.05). Among the 26 patients who underwent laser photocoagulation, serum Ang-2 and VEGF levels significantly decreased(both P 【0.05), whereas serum Ang-1 level and Ang-1/Ang-2ratio were weakly increased(P 】0.05). The median levels of Ang-2 and VEGF in serum were highest in PDR group,however, Ang-1/Ang-2 ratio of PDR group was lowest in three groups.·CONCLUSION: Laser photocoagulation can reduce serum Ang-2 and VEGF levels. The Ang/Tie system and VEGF play an important role in the development and progression of T2 DM patients with PDR.

STAT3 Inhibition by Centipede Scolopendra Extract in Liver Cancer HepG2 Cells and Orthotopic Mouse Models of Hepatocellular Carcinoma

Objective To observe the effects of Centipede Scolopendra extraction(CSE)on human liver cancer HepG2 cells and the nude mouse tumor model of liver orthotopic transplantation,and to explore the anti-liver cancer mechanism of the extract.Methods HepG2 cells were respectively treated with CSE250(250μg/mL),CSE500(500μg/mL)and 5-FU,and control group was established.An enzymatic hydrolysis and acetone precipitation method was used to separate and purify CSE,which was then used to treat HepG2 cells.The CCK8 assay was used to detect the inhibition of cell proliferation and the half maximal inhibitory concentration(IC50)was calculated.Flow cytometry was used to analyze the cell cycle,and western blot was used to detect the expression of signal transduction and activator of transcription 3(STAT3)pathway-related proteins in HepG2 cells treated with CSE.A nude mouse model with an orthotopic liver tumor was prepared.The mice were randomly divided into four groups,each containing 12 animals:the model group,the 5-FU group,the CSE10 group[10 mg/(kg·d)]and the CSE50 group[50 mg/(kg·d)].The volume and mass changes in the nude mice with orthotopic transplanted tumors were observed.Western blot method was used to test the protein expression levels of p-STAT3 and p38 mitogen-activated protein kinase(p38MAPK).Tissues from the liver of mice in the model group and the CSE50 group were analyzed by using a protein tyrosine kinase(PTK)chip,and the Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)function enrichment analysis of the differentially expressed proteins was performed.Results This study showed that CSE significantly inhibited the proliferation of HepG2 cells(P<0.05).After 48 h of CSE treatment,the cell cycle of HepG2 cells manifested as S phase and G2/M phase;p-STAT3 protein levels in the CSE groups were significantly lower than that in the control group(P<0.05).Analysis of the tumor inhibition in the mice showed that the tumor masses and volume in CSE groups were lower(P<0.05).The protein levels of p-STAT3 and p38MAPK in CSE50 group and 5-FU group decreased significantly(P<0.05).PTK antibody chip screening results showed that CSE groups had a bidirectional regulation trend,and there were 23 up-regulated PTKs and six down-regulated PTKs.The GO and KEGG analyses showed that CSE exerted its anticancer effects through regulation of biological processes,including mitogen-activated protein kinase(MAPK)cascade,chemotaxis,cell invasion,cell adhesion,angiogenesis and other biological processes,and through signaling pathways,including the MAPK,phosphatidylinositol-3-kinase/serine threonine protein kinase(PI3K/AKT),and RAS signaling pathways.Conclusions CSE can effectively inhibite the proliferation of HepG2 cells and effectively inhibite the growth of liver cancer orthotopic transplantation tumor.Its mechanism may be closely related to the regulation of STAT3,MAPK and PI3K/AKT signaling pathways.

NEW DRUG TARGETING TREATMENT-GLIVEC

This review evaluates the role of Glivec in the treatment of chronic myelogenous leukemia and other malignant tumors. Preclinical and clinical evidence showed that Glivec demonstrated a potent and specific inhibition on BCR-ABL positive leukemias and other malignant tumors in which overexpression of c-kit and PDGFR-b played a major role in their pathogenesis. Glivec has induced complete hematologic responses in up to 98% of patients evaluated in clinical trials. It's a very successful drug that supported the idea of targeted therapy through inhibition of tyrosine kinases. Although it's still in the early stages of clinical development and the resistance to Glivec remains to be a problem needed further study, a great deal has been learned from these research and observation. And with the increasing data, molecular targeting therapy will play much more important role in the treatment of malignant tumors. With the better understanding of the pathogenesis of malignant tumors, well-designed drugs targeting the specific molecular abnormalities with higher efficacy and lower side effect will benefit numerous patients with malignant tumors.

Signal transduction of bombesin-induced circular smooth muscle cell contraction in cat esophagus

AIM： To investigate the mechanism of bombesin-induced circular smooth muscle cell contraction in cat esophagus. METHODS： Specific G protein or phospholipase C involved in cat esophagus contraction was identified, muscle cells were permeabilized with saponin. After per- meabilization of muscle cells, the Gi3 antibody inhibited bombesin-induced smooth muscle cell contraction. RESULTS： Incubation of permeabilized circular muscle cells with PLC-β3 antibody could inhibit bombesin-induced contraction. H-7, chelerythrine （PKC inhibitor） and genistein （protein tyrosine kinase inhibitor） inhibited bombesin-induced contraction, but DAG kinase inhibitor, R59949, could not inhibit it. To examine which mitogen-activated protein kinase （MAPK） was involved in bombesin-induced contTaction, the specific MAPK inhibitors （MEK inhibitor, PD98059 and p38 MAPK inhibitor, SB202190） were used. Preincubation of PD98059 blocked the contraction induced by bombesin in a concentration-dependent manner. However, SB202190 had no effects on contraction. CONCLUSION： Bombesin-induced circular muscle cell contraction in cat esophagus is mediated via a PKC or a PTK-dependent pathway or p44/p42 HAPK pathway.

Effect of genistein on voltage-gated potassium channels in guinea pig proximal colon smooth muscle cells

AIM： To investigate the action of genistein （GST）, a broad spectrum tyrosine kinase inhibitor, on voltagegated potassium channels in guinea pig proximal colon smooth muscle cells. METHODS： Smooth muscle cells in guinea pig proximal colon were enzymatically isolated. Nystatin-perforated whole cell patch clamp technique was used to record potassium currents including fast transient outward current （Ikto） and delayed rectifier current （Ikdr）, tWO of which were isolated pharmacologically with 10 mmol/L tetraethylammonium or 5 mmol/L 4-aminopyridine. Contamination of calcium-dependent potassium currents was minimized with no caldum and 0.2 mmol/L CdCl2 in an external solution. RESULTS： GST （10-100 μmol/L） reversibly and dosedependently reduced the peak amplitude of Ikto with an IC50 value of 22.0±6.9 μmol/L. To a lesser extent, Ikdr, was also inhibited in both peak current and sustained current. GST could not totally block the outward potassium current as a fraction of the outWard potassium current, which was insensitive to GST. GST had no effect on the steady-state activation （n =6） and inactivation kinetics （n =6） of Ikto. Sodium orthovanadate （1 retool/L）, a potent inhibitor of tyrosine phosphatase, significantly inhibited GST-induced inhibition （P〈 0.05）. CONCLUSION： GST can dose-dependently and reversibly block voltage-gated potassium channels in guinea pig proximal colon smooth muscle cells.

Expression, purification, and bioactivity of GST-fused v-Src from a bacterial expression system

v-Src is a non-receptor protein tyrosine kinase involved in many signal transduction pathways and closely related to the activation and development of cancers. We present here the expression, purification, and bioactivity of a GST (glutathione S-transferase)-fused v-Src from a bacterial expression system. Different culture conditions were examined in an isopropyl β-D-thiogalactopyranoside (IPTG)-regulated expression, and the fused protein was purified using GSH (glutathione) affinity chromatography. ELISA (enzyme-linked immunosorbent assay) was employed to determine the phosphorylation kinase activity of the GST-fused v-Src. This strategy seems to be more promising than the insect cell system or other eukaryotic systems em- ployed in earlier Src expression.

Isolation and Characterization of GmSTY1,a Novel Gene Encoding a Dual-Specificity Protein Kinase in Soybean（ Glycme max L.）

Phosphorylation of protein klnases has profound effects on their activity and interaction with other proteins. Tyroslne phosphorylation was reported to be involved in various physiological processes in plants; however, no typical receptor tyrosine kinase has been isolated from plants thus far. Dual-specificity kinases are potentially responsible for the phosphorylation of both tyrosine and serine/threonine of target proteins. A cDNA clone encoding a putative dual-specificity protein kinase was isolated by screening the cDNA GAL4 activation domain （AD） fusion library of soybean （Glycine max L.）, and its entire length was obtained using 5＇-rapid ampUflcatlon of cDNA ends. The predicted polypeptide of 330 amino acid residues, designated as GmSTY1, contains all 11 conserved subdomains, which share common characteristics with both the serine/ threonine and tyroslne protein klnases reported thus far. In addition, three potential N-linked glycosylation sites （NXS/T）, as well as phosphorylation motifs （SXXXS/T）, were observed, suggesting that GmSTY1 may be post-translationally modified. Furthermore, a potential N-myristoylation motif （MGARCSK） was found, suggesting that the GmSTY1 protein could associate with membranes in vivo. Southern blotting analysis revealed a single-copy of GmSTY1 in the genome. Northern blotting analysis showed that this gene was upregulated by drought and salt treatment in a time-dependent manner; however, exogenous abscisic acid （ABA） could not significantly affect the mRNA accumulation of GmSTY1. Interestingly, the transcript of this gene was remarkably downregulated by cold treatment during the early stages of the response, but upregulated later. These results Indicate that the protein kinase was possibly regulated by abiotic stresses in an ABA-independent pathway.

Hyperglycemia activates FGFR1 via TLR4/c-Src pathway to induce inflammatory cardiomyopathy in diabetes

Protein tyrosine kinases (RTKs) modulate a wide range of pathophysiological events in several non-malignant disorders, including diabetic complications. To find new targets driving the development of diabetic cardiomyopathy (DCM), we profiled an RTKs phosphorylation array in diabetic mouse hearts and identified increased phosphorylated fibroblast growth factor receptor 1 (p-FGFR1) levels in cardiomyocytes, indicating that FGFR1 may contribute to the pathogenesis of DCM. Using primary cardiomyocytes and H9C2 cell lines, we discovered that high-concentration glucose (HG) transactivates FGFR1 kinase domain through toll-like receptor 4 (TLR4) and c-Src, independent of FGF ligands. Knocking down the levels of either TLR4 or c-Src prevents HG-activated FGFR1 in cardiomyocytes. RNA-sequencing analysis indicates that the elevated FGFR1 activity induces pro-inflammatory responses via MAPKs–NFκB signaling pathway in HG-challenged cardiomyocytes, which further results in fibrosis and hypertrophy. We then generated cardiomyocyte-specific FGFR1 knockout mice and showed that a lack of FGFR1 in cardiomyocytes prevents diabetes-induced cardiac inflammation and preserves cardiac function in mice. Pharmacological inhibition of FGFR1 by a selective inhibitor, AZD4547, also prevents cardiac inflammation, fibrosis, and dysfunction in both type 1 and type 2 diabetic mice. These studies have identified FGFR1 as a new player in driving DCM and support further testing of FGFR1 inhibitors for possible cardioprotective benefits.

Csk-homologous kinase （Chk/Matk）： a molecular policeman suppressing cancer formation and progression

Aberrant activation of Src-family tyrosine kinases （SFKs） directs initiation of metastasis and development of drug resistance in multiple solid tumors and hematological cancers. Since oncogenic mutations of SFKs are rare events, aberrant activation of SFKs in cancer is likely due to dysregulation of the two major upstream inhibitors： C-terminal Src kinase （Csk） and its homolog Csk-homologous kinase （Chk/Matk）. Csk and Chk/Matk inhibit SFKs by selectively phosphorylating the inhibitory tyrosine residue at their C-terminal tail. Additionally, Chk/Matk can also employ a non- catalytic inhibitory mechanism to inhibit multiple active forms of SFKs, suggesting that Chk/Matk is a versatile inhibitor capable of constraining the activity of multiple active forms of SFKs. Mounting evidence suggests that Chk/ Mark is a potential tumor suppressor downregulated by epigenetic silencing and/or missense mutations in several cancers such as colorectal and lung carcinoma. In spite of the potential significance of Chk/Matk in cancer, little is known about its structure and regulation. This review focuses on the mechanisms by which Chk/Matk expression and activity is downregulated in cancers. Specifically, we assessed the evidence demonstrating downregulation of Chk/Matk by epigenetic silencing and missense mutations in cancers. The other focus is the tumor suppressive mechanism of Chk/ Matk. The final focus of the review is on the clinical applications of the investigations into the mechanism of epigenetic silencing of Chk/Matk expression and the tumor suppressive mechanism of Chk/Matk; specifically we discussed how they can benefit the development of biomarkers for early diagnosis of cancers and specific SFK inhibitors for use as cancer therapeutics.

New First-line Immunotherapy-based Therapies for Unresectable Hepatocellular Carcinoma: A Living Network Meta-analysis

Background and Aims:Several first-line immune checkpoint inhibitor(ICI)-based combination therapies have been identified for unresectable hepatocellular carcinoma(uHCC).This network meta-analysis(NMA)aimed to provide the most updated evidence about the preferred first-line ICI-based regimens for uHCC.Methods:A comprehensive literature search was performed in various databases from database inception to May 2022.The phase 3 trials evaluating first-line single-agent ICIs,molecular-target agents(MTAs),or their combinations in uHCC were included.The main endpoints were overall survival(OS)and progression-free survival(PFS).Pooled effect estimates were calculated using a random effects model within the frequentist framework.Subgroup analyses based on etiology were also conducted.Results:Twelve trials at low risk of bias with 8,275 patients comparing 13 treatments were included.OS with atezolizumab plus bevacizumab was comparable to sintilimab plus IBI305[hazard ratio(HR):1.16;95%confidence interval(CI):0.80–1.68]and camrelizumab plus apatinib(HR:1.06;95%CI:0.75–1.51).The combination therapies,apart from atezolizumab plus cabozantinib in OS and durvalumab plus tremelimumab in PFS,had higher P-score than single-agent MTAs or ICIs.The survival benefits were associated with a high risk of adverse events leading to treatment discontinuation.The proportion of patients with hepatitis B virus-related HCC receiving ICIs combinations might positively correlate with survival advantages(R2=0.8039,p=0.0155).Conclusion:This NMA demonstrated that atezolizumab plus bevacizumab remains the stand of care and confers comparable survival benefits to sintilimab plus IBI305 and camrelizumab plus apatinib in first-line therapy for uHCC.The optimal treatment algorithms should consider efficacy,safety,and etiology.

RET kinase alterations in targeted cancer therapy

The rearranged during transfection(RET)gene encodes a protein tyrosine kinase.RET alterations by point mutations and gene fusions were found in diverse cancers.RET fusions allow abnormal expression and activation of the oncogenic kinase,whereas only a few of RET point mutations found in human cancers are known oncogenic drivers.Earlier studies of RET-targeted therapy utilized multi-targeted protein tyrosine kinase inhibitors(TKIs)with RET inhibitor activity.These multi-targeted TKIs often led to high-grade adverse events and were subject to resistance caused by the gatekeeper mutations.Recently,two potent and selective RET TKIs,pralsetinib(BLU-667)and selpercatinib(LOXO-292),were developed.High response rates to these selective RET inhibitors across multiple forms of RET alterations in different types of cancers were observed in clinical trials,demonstrating the RET dependence in human cancers harboring these RET lesions.Pralsetinib and selpercatinib were effective in inhibiting RETV804L/M gatekeeper mutants.However,adaptive mutations that cause resistance to pralsetinib or selpercatinib at the solvent front RETG810 residue have been found,pointing to the need for the development of the next-generation of RET TKIs.

Kinases and glutathione transferases:selective and sensitive targeting

Kinases,representing almost 500 proteins in the human genome,are responsible for catalyzing the phosphorylation reaction of amino acid residues at their targets.As the largest family of kinases,the protein tyrosine kinases(PTKs)have roles in controlling the essential cellular activities,and their deregulation is generally related to pathologic conditions.The recent efforts on identifying their signal transducer or mediator role in cellular signaling revealed the interaction of PTKs with numerous enzymes of different classes,such as Ser/Thr kinases(STKs),glutathione transferases(GSTs),and receptor tyrosine kinases(RTKs).In either regulation or enhancing the signaling,PTKs are determined in close interaction with these enzymes,under specific cellular conditions,such as oxidative stress and inflammation.In this concept,intensive research on thiol metabolizing enzymes recently showed their involvement in the physiologic functions in cellular signaling besides their well known traditional role in antioxidant defense.The shared signaling components between PTK and GST family enzymes will be discussed in depth in this research review to evaluate the results of recent studies important in drug targeting for therapeutic intervention,such as cell viability,migration,differentiation and proliferation.

Ginseng-Derived Panaxadiol Saponins Promote Hematopoiesis Recovery in Cyclophosphamide-Induced Myelosuppressive Mice:Potential Novel Treatment of Chemotherapy-Induced Cytopenias

Objective：To investigate the potential efficacy of panaxadiol saponins component（PDS-C）,a biologically active fraction isolated from total ginsenosides,to reverse chemotherapy-induced myelosuppression and pancytopenia caused by cyclophamide（CTX）.Methods：Mice with myelosuppression induced by CTX were treated with PDS-C at a low-（20 mg/kg）,moderate-（40 mg/kg）,or high-dose（80 mg/kg） for 7 consecutive days.The level of peripheral white blood cell（WBC）,neutrophil（NEU） and platelet（PLT） were measured,the histopathology and colony formation were observed,the protein kinase and transcription factors in hematopoietic cells were determined by immunohistochemical staining and Western blot.Results：In response to PDS-C therapy,the peripheral WBC,NEU and PLT counts of CTX-induced myelosuppressed mice were significantly increased in a dose-dependent manner.Similarly,bone marrow histopathology examination showed reversal of CTX-induced myelosuppression with increase in overall bone marrow cellularity and the number of hematopoietic cells（P〈0.01）.PDS-C also promoted proliferation of granulocytic and megakaryocyte progenitor cells in CTX-treated mice,as evidenced by significantly increase in colony formation units-granulocytes/monocytes and-megakaryocytes（P〈0.01）.The enhancement of hematopoiesis by PDS-C appears to be mediated by an intracellular signaling pathway,this was evidenced by the up-regulation of phosphorylated mitogen-activated protein kinase（p-MEK） and extracellular signal-regulated kinases（p-ERK）,and receptor tyrosine kinase（C-kit） and globin transcription factor 1（GATA-1） in hematopoietic cells of CTX-treated mice（P〈0.05）.Conclusions：PDS-C possesses hematopoietic growth factor-like activities that promote proliferation and also possibly differentiation of hematopoietic progenitor cells in myelosuppressed mice,probably mediated by a mechanism involving MEK and ERK protein kinases,and C-kit and GATA-1 transcription factors.PDS-C may potentially be a novel treatment of myelosuppression and pancytopenia caused by chemotherapy.