Checkpoint kinase 1 in colorectal cancer:Upregulation of expression and promotion of cell proliferation

BACKGROUND Colorectal cancer(CRC)is a prevalent malignant tumor characterized by a high mortality rate,with significant challenges persisting in the identification and management of its metastatic stage.The role of checkpoint kinase 1(CHEK1),a cell cycle checkpoint kinase,in CRC has not been fully clarified.We hypothesize that the upregulation of CHEK1 may enhance the proliferation of CRC cells,indicating its potential as a novel therapeutic target for CRC therapy.AIM To investigate the expression and function of CHEK1 in CRC,this study utilizes single-cell RNA sequencing and tissue microarray data.METHODS Single-cell RNA sequencing technology was employed to analyze CRC cells from the GSE144735 dataset,and immunohistochemistry was conducted to confirm the expression of CHEK1 in CRC and adjacent tissues.We also integrated mRNA expression data from multiple public databases to assess global CHEK1 expre-ssion in CRC.Molecular docking experiments were performed to explore the in-teraction between CHEK1 and the potential drug nitidine chloride(NC),as well as to investigate the influence of CHEK1 on CRC cell proliferation.RESULTS We found comparatively elevated CHEK1 expression in the malignant epithelial cells of CRC,with marked upregulation of its mRNA levels in CRC tissues.Immunohistochemical analysis further confirmed the high expression of CHEK1 in CRC tissues,and the receiver operating characteristic curve demonstrated high accuracy(area under the curve=0.964)for CHEK1 as a biomarker.Analysis of global datasets indicated a statistically significant overexpression of CHEK1 in CRC(standard mean difference=1.81,P<0.01),with summary receiver operating characteristic analysis yielding sensitivity and specificity values of 0.83 and 0.88,respectively.Molecular docking studies indicated that NC specifically targeted CHEK1,while clustered regularly interspaced short palindromic repeats knockout experiments demonstrated that CHEK1 promoted CRC cell proliferation.CONCLUSION Upregulation of CHEK1 promotes CRC cell proliferation.However,the dataset's diversity is limited,requiring further investigation into its specific mechanisms.

Polo-like kinase 1 as a biomarker predicts the prognosis and immunotherapy of breast invasive carcinoma patients

Invasive breast carcinoma(BRCA)is associated with poor prognosis and high risk of mortality.Therefore,it is critical to identify novel biomarkers for the prognostic assessment of BRCA.Methods:The expression data of polo-like kinase 1(PLK1)in BRCA and the corresponding clinical information were extracted from TCGA and GEO databases.PLK1 expression was validated in diverse breast cancer cell lines by quantitative real-time polymerase chain reaction(qRT-PCR)and western blotting.Single sample gene set enrichment analysis(ssGSEA)was performed to evaluate immune infiltration in the BRCA microenvironment,and the random forest(RF)and support vector machine(SVM)algorithms were used to screen for the hub infiltrating cells and calculate the immunophenoscore(IPS).The RF algorithm and COX regression model were applied to calculate survival risk scores based on the PLK1 expression and immune cell infiltration.Finally,a prognostic nomogram was constructed with the risk score and pathological stage,and its clinical potential was evaluated by plotting calibration charts and DCA curves.The application of the nomogram was further validated in an immunotherapy cohort.Results:PLK1 expression was significantly higher in the tumor samples in TCGA-BRCA cohort.Furthermore,PLK1 expression level,age and stage were identified as independent prognostic factors of BRCA.While the IPS was unaffected by PLK1 expression,the TMB and MATH scores were higher in the PLK1-high group,and the TIDE scores were higher for the PLK1-low patients.We also identified 6 immune cell types with high infiltration,along with 11 immune cell types with low infiltration in the PLK1-high tumors.A risk score was devised using PLK1 expression and hub immune cells,which predicted the prognosis of BRCA patients.In addition,a nomogram was constructed based on the risk score and pathological staging,and showed good predictive performance.Conclusions:PLK1 expression and immune cell infiltration can predict post-immunotherapy prognosis of BRCA patients.

三氧化二砷对结肠癌SW-480细胞凋亡及polo-like kinase-1基因表达的影响

目的观察三氧化二砷对人结肠癌细胞SW-480并探讨其作用机理。方法采用不同浓度的三氧化二砷作用结肠癌SW-480细胞后,采用MTT法检测细胞的恶性增殖,采用琼脂糖凝胶电泳和流式细胞仪检测凋亡及细胞周期情况,采用定量PCR检测polo-likekinase-1(PLK1)mRNA水平。结果三氧化二砷能抑制结肠癌细胞的恶性增殖,且与浓度相关。三氧化二砷能诱导结肠癌细胞凋亡,且呈浓度依赖性。流式细胞仪检测发现,三氧化二砷将细胞阻滞在G2/M期。三氧化二砷能下调结肠癌PLK1mRNA水平,且呈药物浓度和作用时间依赖性。结论三氧化二砷有效地抑制结肠癌SW-480细胞增殖,其机制可能与其下调PLK1表达,从而诱导凋亡有关。

Present and prospect of transarterial chemoembolization combined with tyrosine kinase inhibitor and PD-1 inhibitor for unresectable hepatocellular carcinoma

In this editorial,we comment on the article(World J Gastrointest Oncol 2024;16:1236-1247),which is a retrospective study of transarterial chemoembolization(TACE)combined with multi-targeted tyrosine kinase inhibitor(TKI)and programmed cell death protein-1(PD-1)inhibitor for the treatment of unresectable hepatocellular carcinoma(HCC).Herein,we focus specifically on the mechanisms of this triple therapy,administration sequence and selection of each medication,and implications for future clinical trials.Based on the interaction mechanisms between medications,the triple therapy of TACE+TKI+PD-1 is proposed to complement the deficiency of each monotherapy,and achieve synergistic antitumor effects.Although this triple therapy has been evaluated by several retrospective trials,it is still controversial whether the triple therapy achieves better clinical benefits,due to the flawed study design and heterogeneity in medications.In addition,the administration sequence,which may greatly affect the clinical benefit,needs to be fully considered at clinical decision-making for obtaining better prognosis.We hope that this editorial could contribute to the design and optimization of future trials.

RNAi沉默Polo-like kinase-1基因表达对胰腺癌细胞增殖的影响

目的:探讨polo-like kinase-1(PLK1)基因在胰腺癌细胞中的作用.方法:采用PLK1小干扰核糖核酸分子(small interfering RNA,siRNA)转染人胰腺癌Mi- aPaCa-2细胞后,分别采用实时定量PCR和Western blot检测PLK1基因mRNA和蛋白表达水平,观察PLK1 siRNA转染对胰腺癌细胞体内外增殖的影响.于转染不同时间后收集细胞,分别采用琼脂糖凝胶电泳和TUNEL方法检测胰腺癌细胞凋亡情况.结果:胰腺癌MiaPaCa-2细胞经siRNA转染处理后,PLK1 mRNA和蛋白表达水平明显下降(P<0.05).PLK1基因siRNA可明显抑制癌细胞体外生长(P<0.05)和体内裸鼠模型增殖(P<0.05).细胞凋亡检测发现,DNA电泳出现明显的梯度图谱,且与浓度相关(r=0.836,P<0.05).TUNEL结果显示,转染组癌细胞凋亡指数明显增加,且呈时间和浓度依赖性(r= 0.875,P<0.05).结论:PLK1 siRNA转染可明显抑制胰腺癌细胞增殖,其机制可能与诱导细胞凋亡有关.

The dual role of casein kinase 1,DTG1,in regulating tillering and grain size in rice

Tiller number and grain size are important agronomic traits that determine grain yield in rice.Here,we demonstrate that DEFECTIVE TILLER GROWTH 1(DTG1),a member of the casein kinase 1 protein family,exerts a co-regulatory effect on tiller number and grain size.We identified a single amino acid substitution in DTG1(I357K)that caused a decrease in tiller number and an increase in grain size in NIL-dtg1.Genetic analyses revealed that DTG1 plays a pivotal role in regulation of tillering and grain size.The DTG1^(I357K) allelic variant exhibited robust functionality in suppressing tillering.We show that DTG1 is preferentially expressed in tiller buds and young panicles,and negatively regulates grain size by restricting cell proliferation in spikelet hulls.We further confirm that DTG1 functioned in grain size regulation by directly interacting with Grain Width 2(GW2),a critical grain size regulator in rice.The CRISPR/Cas9-mediated elimination of DTG1 significantly enhanced tiller number and grain size,thereby increasing rice grain yield under field conditions,thus highlighting potential value of DTG1 in rice breeding.

Interleukin-1 receptor associated kinase 2 is a functional downstream regulator of complement factor D that controls mitochondrial fitness in diabetic cardiomyopathy

Diabetic cardiomyopathy is a disorder of the cardiac muscle that affects patients with diabetes.The exact mechanisms underlying diabetic cardiomyopathy are mostly unknown,but several factors have been implicated in the pathogenesis of the disease and its progression towards heart failure,including endothelial dysfunction,autonomic neuropathy,metabolic alterations,oxidative stress,and alterations in ion homeostasis,especially calcium transients[1].In Military Medical Research,Jiang et al.[2]sought to determine the functional role of complement factor D(Adipsin)in the pathophysiology of diabetic cardiomyopathy.

Diabetes and high-glucose could upregulate the expression of receptor for activated C kinase 1 in retina

BACKGROUND Diabetic retinopathy(DR)is a major ocular complication of diabetes mellitus,leading to visual impairment.Retinal pigment epithelium(RPE)injury is a key component of the outer blood retinal barrier,and its damage is an important indicator of DR.Receptor for activated C kinase 1(RACK1)activates protein kinase C-ε(PKC-ε)to promote the generation of reactive oxygen species(ROS)in RPE cells,leading to apoptosis.Therefore,we hypothesize that the activation of RACK1 under hypoxic/high-glucose conditions may promote RPE cell apoptosis by modulating PKC-ε/ROS,thereby disrupting the barrier effect of the outer blood retinal barrier and contributing to the progression of DR.AIM To investigate the role and associated underlying mechanisms of RACK1 in the development of early DR.METHODS In this study,Sprague-Dawley rats and adult RPE cell line-19(ARPE-19)cells were used as in vivo and in vitro models,respectively,to explore the role of RACK1 in mediating PKC-εin early DR.Furthermore,the impact of RACK1 on apoptosis and barrier function of RPE cells was also investigated in the former model.RESULTS Streptozotocin-induced diabetic rats showed increased apoptosis and upregulated expression of RACK1 and PKC-εproteins in RPE cells following a prolonged modeling.Similarly,ARPE-19 cells exposed to high glucose and hypoxia displayed elevated mRNA and protein levels of RACK1 and PKC-ε,accompanied by an increases in ROS production,apoptosis rate,and monolayer permeability.However,silencing RACK1 significantly downregulated the expression of PKC-εand ROS,reduced cell apoptosis and permeability,and protected barrier function.CONCLUSION RACK1 plays a significant role in the development of early DR and might serve as a potential therapeutic target for DR by regulating RPE apoptosis and barrier function.

Potential of ginsenoside Rg1 to treat aplastic anemia via mitogen activated protein kinase pathway in cyclophosphamide-induced myelosuppression mouse model

Aplastic anemia(AA)is a rare but serious condition in which the bone marrow fails to produce sufficient new blood cells,leading to fatigue,increased susceptibility to infection,and uncontrolled bleeding.In this editorial,we review and comment on an article by Wang et al published in 2024.This study aimed to evaluate the potential therapeutic benefits of ginsenoside Rg1 in AA,focusing on its protective effects and uncovering the underlying mechanisms.Cyclophosphamide(CTX)administration caused substantial damage to the structural integrity of the bone marrow and decreased the number of hematopoietic stem cells,thereby establishing an AA model.Compared with the AA group,ginsenoside Rg1 alleviated the effects of CTX by reducing apoptosis and inflammatory factors.Mechanistically,treatment with ginsenoside Rg1 significantly mitigated myelosuppression in mice by inhibiting the mitogen activated protein kinase signaling pathway.Thus,this study indicates that ginsenoside Rg1 could be effective in treating AA by reducing myelosuppression,primarily through its influence on the mitogen activated protein kinase signaling pathway.We expect that our review and comments will provide valuable insights for the scientific community related to this research and enhance the overall clarity of this article.

MicroRNA-298 determines the radio-resistance of colorectal cancer cells by directly targeting human dual-specificity tyrosine(Y)-regulated kinase 1A

BACKGROUND Radiotherapy stands as a promising therapeutic modality for colorectal cancer(CRC);yet,the formidable challenge posed by radio-resistance significantly undermines its efficacy in achieving CRC remission.AIM To elucidate the role played by microRNA-298(miR-298)in CRC radio-resistance.METHODS To establish a radio-resistant CRC cell line,HT-29 cells underwent exposure to 5 gray ionizing radiation that was followed by a 7-d recovery period.The quantification of miR-298 levels within CRC cells was conducted through quantitative RT-PCR,and protein expression determination was realized through Western blotting.Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and proliferation by clonogenic assay.Radio-induced apoptosis was discerned through flow cytometry analysis.RESULTS We observed a marked upregulation of miR-298 in radio-resistant CRC cells.MiR-298 emerged as a key determinant of cell survival following radiation exposure,as its overexpression led to a notable reduction in radiation-induced apoptosis.Intriguingly,miR-298 expression exhibited a strong correlation with CRC cell viability.Further investigation unveiled human dual-specificity tyrosine(Y)-regulated kinase 1A(DYRK1A)as miR-298’s direct target.CONCLUSION Taken together,our findings underline the role played by miR-298 in bolstering radio-resistance in CRC cells by means of DYRK1A downregulation,thereby positioning miR-298 as a promising candidate for mitigating radioresistance in CRC.

Crosslink among cyclin-dependent kinase 9,ATP binding cassette transporter G2 and Beclin 1 in colorectal cancer

Colorectal cancer(CRC)ranks third in the number of cancers mainly because of the inability to diagnose it at an early stage.The pathogenesis of CRC is complicated,which is the result of the complex interaction of multiple genetic and environmental factors.Currently,one of the main treatments for CRC is chemotherapy.But the primary cause of CRC treatment failure is drug resistance.The expression of cyclin-dependent kinase 9(CDK9)was correlated with elevated autophagy levels in colon cancer,and high expression of CDK9 indicates a poor prognosis in CRC.The incidence of autophagy and the expressions of Beclin 1 and ATP binding cassette transporter G2 are different in left and right colon cancer,and autophagy may be involved in the occurrence of chemotherapy resistance.In this article,the roles of CDK9,ATP binding cassette transporter G2 and Beclin 1 in CRC were elucidated,emphasizing the linkages among them and providing potential therapeutic targets of CRC.

Bibliometric analysis of phosphoglycerate kinase 1 expression in breast cancer and its distinct upregulation in triple-negative breast cancer

BACKGROUND Phosphoglycerate kinase 1(PGK1)has been identified as a possible biomarker for breast cancer(BC)and may play a role in the development and advancement of triple-negative BC(TNBC).AIM To explore the PGK1 and BC research status and PGK1 expression and mecha-nism differences among TNBC,non-TNBC,and normal breast tissue.METHODS PGK1 and BC related literature was downloaded from Web of Science Core Co-llection Core Collection.Publication counts,key-word frequency,cooperation networks,and theme trends were analyzed.Normal breast,TNBC,and non-TNBC mRNA data were gathered,and differentially expressed genes obtained.Area under the summary receiver operating characteristic curves,sensitivity and specificity of PGK1 expression were determined.Kaplan Meier revealed PGK1’s prognostic implication.PGK1 co-expressed genes were explored,and Gene Onto-logy,Kyoto Encyclopedia of Genes and Genomes,and Disease Ontology applied.Protein-protein interaction networks were constructed.Hub genes identified.RESULTS PGK1 and BC related publications have surged since 2020,with China leading the way.The most frequent keyword was“Expression”.Collaborative networks were found among co-citations,countries,institutions,and authors.PGK1 expression and BC progression were research hotspots,and PGK1 expression and BC survival were research frontiers.In 16 TNBC vs non-cancerous breast and 15 TNBC vs non-TNBC datasets,PGK1 mRNA levels were higher in 1159 TNBC than 1205 non-cancerous breast cases[standardized mean differences(SMD):0.85,95%confidence interval(95%CI):0.54-1.16,I²=86%,P<0.001].PGK1 expression was higher in 1520 TNBC than 7072 non-TNBC cases(SMD:0.25,95%CI:0.03-0.47,I²=91%,P=0.02).Recurrence free survival was lower in PGK1-high-expression than PGK1-low-expression group(hazard ratio:1.282,P=0.023).PGK1 co-expressed genes were concentrated in ATP metabolic process,HIF-1 signaling,and glycolysis/gluconeogenesis pathways.CONCLUSION PGK1 expression is a research hotspot and frontier direction in the BC field.PGK1 may play a strong role in promoting cancer in TNBC by mediating metabolism and HIF-1 signaling pathways.

Overexpression of polo-like kinase1 predicts a poor prognosis in hepatocellular carcinoma patients

AIM： To elucidate the role of overexpressed polo-like kinasel （PLK1）in hepatocellular carcinoma （HCC）. METHODS： We prospectively collected clinicopathological, immunohistochemical and semi-quantitative reverse transcription-polymerase chain reaction （RT-PCR） data from 135 HCC patients undergoing successful hepatectomy. The correlations between PLK1 mRNA expression and clinicopathologic variables were analyzed by Mann-Whitney U test. Prognostic factors were identified by univariate and multivariate analyses. RESULTS： Immunohistochemical results showed overexpression of PLK1 was mainly found in tumor tissues compared with tumor-free tissue. A similar mRNA result was obtained by semi-quantitative RT-PCR. A total of 111 samples were positive for PLK1 mRNA expression. The positive expression was correlated with venous invasion, tumor nodules and Edmondson grade. Furthermore, 1, 3, 5-year survival rates in the positive expression group were significantly lower than the negative control group. Multivariate analysis showed that positive PLK1 expression was an independent risk factor for HCC. CONCLUSION： PLK1 could be a potential biomarker for diagnosis and therapy for HCC.

Polo-like kinase 1,a new therapeutic target in hepatocellular carcinoma

AIM： To investigate the role of polo-like kinase 1 （PLK1） as a therapeutic target for hepatocellular carcinoma （HCC）. METHODS： PLK1 gene expression was evaluated in HCC tissue and HCC cell lines. Gene knockdown with short-interfering RNA （siRNA） was used to study PLK1 gene and protein expression using real-time reverse transcription polymerase chain reaction （RT-PCR） and Western blotting, and cell proliferation using 3-（4,5-dim ethylthiazol-2-yl）-5-（3-carboxymethoxyphenyl）-2（4-sulf ophenyl）-2H-tetrazolium （MTS） and bromodeoxyuridine （BrdU） assays. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase dUTP nick end label- ing （TUNEL） assay, and caspase-inhibition assay. Huh-7 cells were transplanted into nude mice and co-cultured with PLK1 siRNA or control siRNA, and tumor progres- sion was compared with controls. RESULTS： RT-PCR showed that PLK1 was overexpre- ssed 12-fold in tumor samples compared with controls, and also was overexpressed in Huh-7 cells, siRNA against PLK1 showed a reduction in PLK1 gene and protein expression of up to 96% in Huh-7 cells, and a reduction in cell proliferation by 68% and 92% in MTS and BrdU cell proliferation assays, respectively. There was a 3-fold increase in apoptosis events, and TUNEL staining and caspase-3 assays suggested that this was caspase-independent. The pan-caspase inhibitor Z-VAD-FMK was unable to rescue the apoptotic cells. Immnofluorescence co-localized endonuclease-G to fragmented chromosomes, implicating it in apoptosis. Huh-7 cells transplanted subcutaneously into nude mice showed tumor regression in siPLKl-treated mice, but not in controls. CONCLUSION： Knockdown of PLK1 overexpression in HCC was shown to be a potential therapeutic target, leading to apoptosis through the endonuclease-G path- way.

Dual targeting of Polo-like kinase 1 and baculoviral inhibitor of apoptosis repeat-containing 5 in TP53-mutated hepatocellular carcinoma

BACKGROUND Hepatocellular carcinoma(HCC),often diagnosed at advanced stages without curative therapies,is the fifth most common malignant cancer and the second leading cause of cancer-related mortality.Polo-like kinase 1(PLK1)is activated in the late G2 phase of the cell cycle and is required for entry to mitosis.Interestingly,PLK1 is overexpressed in many HCC patients and is highly associated with poor clinical outcome.Baculoviral inhibitor of apoptosis repeatcontaining 5(BIRC5)is also highly overexpressed in HCC and plays key roles in this malignancy.AIM To determine the expression patterns of PLK1 and BIRC5,as well as their correlation with p53 mutation status and patient clinical outcome.METHODS The expression patterns of PLK1 and BIRC5,and their correlation with p53 mutation status or patient clinical outcome were analyzed using a TCGA HCC dataset.Cell viability,cell apoptosis,and cell cycle arrest assays were conducted to investigate the efficacy of the PLK1 inhibitors volasertib and GSK461364 and the BIRC5 inhibitor YM155,alone or in combination.The in vivo efficacy of volasertib and YM155,alone or in combination,was assessed in p53-mutated Huh7-derived xenograft models in immune-deficient NSIG mice.RESULTS Our bioinformatics analysis using a TCGA HCC dataset revealed that PLK1 and BIRC5 were overexpressed in the same patient subset and their expression was highly correlated.The overexpression of both PLK1 and BIRC5 was more frequently detected in HCC with p53 mutations.High PLK1 or BIRC5 expression significantly correlated with poor clinical outcome.PLK1 inhibitors(volasertib and GSK461364)or a BIRC5 inhibitor(YM155)selectively targeted Huh7 cells with mutated p53,but not HepG2 cells with wild-type p53.The combination treatment of volasertib and YM155 synergistically inhibited the viability of Huh7 cells via apoptotic pathway.The efficacy of volasertib and YM155,alone or in combination,was validated in vivo in a Huh7-derived xenograft model.CONCLUSION PLK1 and BIRC5 are highly co-expressed in p53-mutated HCC and inhibition of both PLK1 and BIRC5 synergistically compromises the viability of p53-mutated HCC cells in vitro and in vivo.

Effect of Antisense RNA Targeting Polo-like Kinase 1 on Cell Growth in A549 Lung Cancer Cells

In order to investigate the effect of Polo-like kinase-1 （Plk1） depletion on cell cycle progression and cell growth in lung cancer cells, a recombinant plasmid containing antisense RNA targeting Plk1 （pcDNA3-Plk1） was transfected into A549 cells by lipofectine. RT-PCR and Western-blot were used to detect the Plk1 gene expression. Cell proliferation was evaluated by direct cell counting and bromodeoxyuridine （BrdU） labeling. Cell cycle distribution and apoptosis were examined by flow cytometry, and the inhibition rate （IR） by vinorebline （NVB） was determined by MTF assay. The results showed that after transfection of pcDNA3-Plk1 into A549 cells, the expression levels of Plk1 mRNA and protein were greatly decreased. In pcDNA3-Plk1 transfected groups, abnormal morphological changes of cells and growth inhibition were observed, and the BrdU labeling index was significantly lower than in the control groups （P〈0.05）. Cells in pcDNA3-Plk1 transfected groups were arresed in G2/M phase and apoptosis was detectable 72 h post transfection. IR induced by vinorebline in pcDNA3-Plk1 transfected groups was significantly higher than in other groups. These data suggested that antisense RNA targeting Plk1 could suppress the Plk1 expression, and therefore, significantly inhibit cell proliferation and induce cell cycle arrest and apoptosis. Moreover, it sensitized lung cancer cells to chemotherapy.

Doublecortin-like kinase 1在消化系统肿瘤中的表达及意义

随着人们对于消化道肿瘤的研究逐渐深入,诊断方法和治疗手段需要更加直接和准确。寻找可靠的肿瘤干细胞标志物一直是肿瘤研究中的重点。Doublecortin-like kinase 1(DCLK1)是近些年发现的可能的癌干细胞标志物之一,在多种恶性肿瘤组织中表达,如结直肠癌、胰腺肿瘤、前列腺癌、肝细胞癌等,并且在肿瘤的发展过程中起到功能性作用。本文综述DCLK1的结构及其在消化系统肿瘤中表达意义的相关文献,为DCLK1的有关研究和新型抗癌靶向药物研制提供参考。

血管生成素-1激活tyrosine kinase／PI3K增加血管内皮细胞[Mg^2＋]i

目的:探讨血管生成素-1(Ang-1)对人脐静脉内皮细胞(HUVECs)内游离镁离子浓度([Mg2+]i)的调节机制。方法:我们采用荧光指示剂mag-fura-2,运用PTi阳离子测定系统动态测HUVECs的[Mg2+]i。结果:Ang-1诱导的[Mg2+]i增加与细胞外Mg2+浓度无关。Ang-1诱导的[Mg2+]i增加与细胞内Ca2+浓度无关。经酪氨酸激酶阻断剂(tyrphostin A23和genistein),磷脂酰3激酶阻断剂(wortmannin和LY294002)预处理,均显著阻断Ang-1诱导的[Mg2+]i增加。但经活化丝裂原激活激酶阻断剂(SB202190和PD98059)预处理,不能阻断Ang-1诱导的[Mg2+]i增加。结论:Ang-1通过酪氨酸激酶/磷脂酰3激酶信号传递途径使细胞内的Mg2+库释放Mg2+,从而增加HUVECs的[Mg2+]i。

Involvement of MAPK/ERK kinase-ERK pathway in exogenous bFGF-induced Egr-1 binding activity enhancement in anoxia-reoxygenation injured astrocytes

Objective Intravenous administration of basic fibroblast growth factor （bFGF） is effective to reduce the volume of cerebral infract due to ischemia. This study was designed to investigate the molecular mechanism, especially the signal transduction pathways, involved in this protective role of bFGF. Methods Anoxia-reoxygenation treated atrocytes were used to study the role of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase （MAPK/ERK kinase, MEK）-ERK signaling pathway after exogenous bFGF administration by Western blot. Electrophoretic mobile shift assay was used to detect the binding activity of early growth response factor-1 （Egr-1）, an important transcription factor for endogenous bFGF. Results bFGF could protect some signal transduction proteins from the oxygen-derived free radicals induced degradation. ERK1/2 was activated and involved in Egr-1 binding activity enhancement induced by exogenous bFGF. Conclusion MEK-ERK MAPK cascade may be an important signal transduction pathway contributed to bFGF induced enhancement of Egr-1 binding activity in anoxia-reoxygenation injured astrocytes.

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.