p21WAF1抑制K562细胞生长并降低其对足叶乙甙的敏感性

目的探讨p21WAF1对白血病细胞系K562增殖及其对化疗药物足叶乙甙(Vp16)敏感性的影响.方法构建p21WAF1逆转录病毒表达载体pLXSN-p21WAF1,将pLXSN-p21WAF1和空载体pLXSN-neo通过FuGENETM6介导体外转染p21WAF1表达缺如的K562细胞,经筛选得到G418抗性K562细胞株,用RT-PCR和Western blot证明该基因在转染后的K562细胞中有表达,用锥虫蓝染色法和流式细胞术检测p21WAF1对K562细胞增殖和细胞周期的影响,用活细胞计数法和MTT法检测转染p21WAF1的K562细胞对Vp16敏感性变化.结果表达外源性p21WAF1的K562细胞生长明显慢于对照组细胞,流式细胞术检测显示G0/G1期细胞增多,活细胞计数法和MTT法显示K562-p21WAF1细胞对化疗药物Vp16的药物敏感性明显降低,Vp16对K562-neo细胞的IC50值为(56.4±6.5)μg/ml, 而对K562-p21WAF1细胞的IC50值为(131.0±8.7)μg/ml,两者相比差异有显著性(P<0.01).结论 p21WAF1能抑制K562细胞增殖,但同时降低了K562细胞对Vp16的敏感性.     

丙戊酸钠对Kasumi-1细胞细胞周期的阻滞作用及其机制探讨

目的 研究组蛋白脱乙酰化酶(HDAC)抑制剂丙戊酸钠(VPA)对白血病细胞系Kasnmi-1细胞周期的影响并探讨其分子机制.方法 不同浓度VPA处理Kasumi-1细胞不同时间,碘化丙锭染色流式细胞术分析细胞周期的变化.RT-PCR及Western blot方法 分析细胞周期蛋白D1(cyclin D1)及周期蛋白依赖性激酶抑制因子p21 WAF1/CIP mRNA或蛋白水平变化.结果 ①VPA抑制Kasumi-1细胞的细胞周期,使其阻滞于G0/G1期.3 mmol/L VPA处理3 d,G0/G1期细胞由(50.7±2.8)%上升至(80.7±1.7)%.②以3 mmol/LVPA处理Kasumi-1细胞不同时间,与对照组比较,3 mmol/L VPA组cyclin D1 mRNA表达水平下调;以不同浓度VPA处理Kasumi-1细胞3 d,结果 发现随着VPA药物浓度增加cyclin D1 mRNA表达水平降低,呈现剂量依赖性.③VPA诱导p21WAF1/CIP mRNA表达明显增加,呈现时间及剂量依赖性.不同浓度VPA处理细胞3 d时,随着用药浓度的增加,p21WF1/CIP蛋白相对表达水平增加,3 mmol/L VPA处理细胞2 d与0 d比较,p21 WAF1/CIP蛋白相对表达水平明显增加(2.498±0.240对0).结论 VPA可以通过对cyclin D1及周期蛋白依赖性激酶抑制因子p21WAF1/CIP调节使Kasumi-1细胞周期阻滞于G0/G1期.     

SHIP基因突变对白血病细胞系K562细胞迁移及侵袭的影响

目的 研究含SH2结构域的肌醇磷酸酶(SHIP)基因碳末端PxxP结构域点突变对细胞体外迁移及侵袭能力的影响及其机制.方法 采用基因转染技术将携带野生型(wt)和突变型(mu)SHIP基因的慢病毒载体感染人白血病细胞系K562细胞;采用实时荧光定量PCR(FQ-PCR)和Western blot法分别在mRNA和蛋白水平检测转染后各组SHIP基因表达水平;采用Transwell小室比较K562/wtSHIP、K562/muSHIP转染后K562细胞跨膜及侵袭能力有无差别;Westem blot法比较各组细胞基质金属蛋白酶( MMP)-2、MMP-9和磷酸化灶性黏着斑激酶(p-FAK)的表达情况,并检测各组细胞NF-KB活性改变.结果 感染慢病毒48 h后FQ-PCR和Westemblot法检测结果显示SHIP基因在K562细胞中表达明显升高;K562/wtSHIP组细胞迁移指数为(15.8±1.4)％,明显低于K562/muSHIP组[(54.3±2.4)％]和转染空载体的细胞对照组[K562/猫免疫缺陷病(pFIV)组,(50.3±3.8)％](P＜0.01);K562/muSHIP组与K562/pFIV组差异无统计学意义(P＞0.05);侵袭实验显示K562/wtSHIP组迁移到碳酸脂膜的细胞[(32±6)/视野]较K562/pFIV细胞[(78±13)/视野]和K562/muSHIP细胞[(83±16)/视野]明显减低.而K562/pFIV细胞与K562/muSHIP细胞比较,在侵袭能力上差异无统计学意义(P＞0.05).K562/muSHIP细胞p-FAK和NF-KB表达明显高于K562/wtSHIP细胞.结论 SHIP基因碳末端PxxP结构域对于SHIP基因负调节功能有重要作用.此位点发生突变通过影响FAK蛋白磷酸化、NF-KB活化以及MMP-9的表达影响K562细胞的体外迁移和侵袭能力;SH IP基因碳末端PxxP结构域点突变可能为致病性突变,可能是白血病细胞中SHIP功能异常的原因之一.     

转染p21WAF1基因对K562白血病细胞系增殖的抑制作用

为了探讨p21WAF1基因对白血病细胞增殖的影响,构建了p21WAF1的逆转录病毒表达载体,通过FuGENETM6介导体外转染p21WAF1表达缺如的K562细胞。经筛选得到G418抗性K562细胞系,用RT-PCR和Western印迹检测到外源p21WAF1的表达,用活细胞计数观察细胞增殖情况,同时进行流式细胞术和软琼脂集落形成实验,结果表明,K562-p21WAF1的表达,用活细胞计数观察细胞增殖情况,同时进行流式细胞术和软琼脂集落形成实验,结果表明,K562-p21WAF1中可检测到P21WAF1蛋白及mRNA表达,细胞增殖明显减慢,G0G1期细胞数增多,细胞在软琼脂中的集落形成能力下降,以上结果表明,p21WAF1基因可抑制p21WAF1表达阴性的白血病细胞增殖,可能成为白血病基因治疗的靶基因。     

ERK和P38信号转导途径对慢性髓系白血病细胞周期的调控作用

本研究探讨ERK和P38信号转导途径对慢性髓系白血病（CML）细胞周期的调控作用。以RT-PCR、Western blot和FCM方法分别检测CML患者白血病细胞和K562细胞中ERK、p38、cyclin D2、cyclin E、p27的mRNA表达及蛋白表达（其中ERK和P38为磷酸化ERK和磷酸化P38）及细胞周期分布,并分析其相关关系。结果表明：CML患者白血病细胞和K562细胞中ERK、P38、cyclin D2、cyclin E的mRNA表达和蛋白表达增高,P27的表达降低,且cyclin D2蛋白表达与cyclin E、ERK和P38蛋白表达呈正相关（P〈0.01）,与P27蛋白表达呈负相关（P〈0.01）。G0/G1期细胞减少,S期细胞增多,与对照组相比有显著性差异。结论：CML中P38、ERK mRNA表达和活性增加,激活下游的cyclin D2、cyclin E和P27等细胞周期调控因子,致使G0/G1期缩短,细胞快速通过G1/S转换点进入S期,加速细胞周期进程和细胞增殖,导致CML的发生。     

靶向沉默Gli1基因表达对K562细胞增殖的影响及其机制探讨

目的 探讨靶向沉默Sonic hedgehog(Shh)信号通路的转录因子Gli1基因表达对K562细胞增殖的影响及其机制.方法 将针对Gli1的小干扰RNA(small interfering RNA,siRNA)通过脂质体(LipofectamineTM 2000)导入K562细胞作为实验组,并以非特异性siRNA为对照组.实时定量PCR和Western blot法检测Gli1 mRNA和蛋白表达,MTT检测细胞增殖,碘化丙锭(PI)检测细胞周期,实时定量PCR检测c-myc、p21基因的表达变化.结果 转染后24 h实验组Gli1 mRNA表达水平为对照组的(52.60±3.57)%(P<0.01),转染后48 h实验组Gli1的蛋白表达水平为对照组的 (79.31±5.58)% (P<0.01).转染后24 h实验组细胞增殖率为对照组的 (94.41±3.58)% (P<0.05),48 h为对照组的(90.22 ±3.34)% (P<0.01).转染后24、48 h 实验组细胞出现G2/M期阻滞且c-myc的表达水平下降,而p21的表达水平升高 (P值均<0.05).结论 靶向沉默Gli1基因表达抑制了K562细胞的增殖,该抑制作用是通过下调c-myc基因、上调p21基因的表达实现的.     

RNA特异性干扰bcr-abl融合基因联合p27基因克隆对K562细胞的影响

本研究旨在探讨RNA干扰抑制慢性髓系白血病bcr-abl融合基因表达,以及RNAi和p27基因克隆联合作用对K562细胞的细胞增殖、细胞周期及凋亡等的调控作用。以细胞系K562为研究对象,合成并转染针对K562细胞bcr-abl融合基因融合位点的21nt siRNA,应用Northern blot法检测bcr-abl融合基因的表达,Western blot法检测BCR-ABL蛋白及凋亡相关蛋白BCL-xL的表达;同时应用RT-PCR扩增p27基因,构建P27-pcDNA3.1载体,转染p27基因入缺失p27基因的K562细胞,经筛选得到G418抗性的K562细胞株;经Western blot证实有P27蛋白表达后,联合应用RNA干扰及p27基因克隆,通过MTT法及流式细胞仪等检测联合作用后对K562细胞的细胞增殖、细胞周期及凋亡等的调控作用。结果表明,RNA干扰组K562细胞bcr-abl融合基因的表达水平明显下降,转染24小时时有18.4%的K562细胞发生凋亡,细胞凋亡相关蛋白BCL-xL的表达水平下调,出现明显的G1期阻滞;表达外源性P27蛋白的P27-pcDNA3.1-K562细胞株生长速度明显慢于对照K562细胞株。流式细胞仪检测显示,G0/G1期细胞增多,S期细胞明显减少;RNA干扰与p27基因克隆联合作用于K562细胞后,凋亡细胞比例明显上升(33.4%)。MTT法显示,细胞存活率较单纯p27-K562细胞组及RNA干扰-K562细胞组均明显下降(p0.01和p0.05)。结论:特异性siRNA分子可以抑制bcr-abl融合基因的表达,诱导K562细胞分化或凋亡。RNA干扰联合p27基因克隆对抑制K562细胞增殖及促凋亡方面具有协同作用。     

KLF4过表达对白血病K562细胞增殖、凋亡的影响

目的:建立稳定过表达人锌指转录因子Krüppel样因子4(Krüppe-like factor 4,KLF4)基因的K562细胞株,研究KLF4过表达对白血病K562细胞增殖、凋亡的影响。方法:将过表达KLF4的重组质粒p EGFP-KLF4电穿孔转染白血病K562细胞,G418压力筛选出稳定转染细胞克隆并扩大培养(K562/p EGFP-KLF4组),设p EGFP-C1空质粒转染K562细胞(K562/p EGFP-C1组)及空白K562细胞对照组。应用荧光显微镜观察EGFP-KLF4融合蛋白的表达,Western blot法检测各组细胞中KLF4蛋白表达水平,MTT比色法检测各组细胞的增殖能力,流式细胞术检测各组细胞的凋亡情况。结果:p EGFP-KLF4重组质粒转染K562细胞后,经G418压力筛选,获得了表达绿色荧光蛋白的稳定细胞株;与对照组相比,K562/p EGFP-KLF4组细胞KLF4的蛋白表达水平明显升高,其过表达率为74.07%(P0.05);过表达KLF4的K562细胞增殖活力被显著抑制(P0.05);过表达KLF4的K562细胞凋亡显著增加(P0.05)。结论:KLF4过表达可抑制K562细胞的增殖,促进其凋亡。     

p16基因克隆联合伊马替尼对慢性粒细胞白血病K562细胞作用的研究

目的：探讨p16基因克隆联合伊马替尼对慢性粒细胞白血病细胞株K562细胞的增殖、周期及凋亡等的调控作用。方法：RT-PCR扩增p16基因，胶纯化回收后连接到T载体测序，序列正确后构建p16-pcDNA3．1载体．将p16-pcDNA3、1与空载体分别以脂质体转染入p16基因缺失的K562细胞。经筛选得到G418抗性的K562细胞株．Westernblot证实转染后有p16蛋白表达。MTT法检测细胞存活率，流式细胞仪检测细胞周期和凋亡。结果：反复测序发现，从K562细胞中扩增的DNA片段属于非特异性扩增。证实K562细胞中p16基因缺失。转染p16基因后表达外源性p16蛋白的p16-pcDNA3、1-K562细胞株生长速度明显减慢；伊马替尼作用于已转染p16-pcDNA3、1的K562细胞．其细胞存活率与伊马替尼作用未转染K562细胞及单纯转染p16-pcDNA3．1的K562细胞相比均明显降低。转染p16基因后G0／G1期细胞增多，S期细胞明显减少，p16．pcDNA3．1-K562细胞与伊马替尼联合应用后凋亡细胞比例明显上升。结论：p16基因抑制K562细胞增殖并调节其周期，外源p16联合应用伊马替尼对抑制K562细胞增殖及促凋亡方面具有协同作用。     

高三尖杉酯碱联合伊马替尼对K562/G01细胞的作用及机制研究

目的:探索高三尖杉酯碱(Homoharringtonine,HHT)联合伊马替尼(Imatinib,IM)对K562/G01细胞增殖、凋亡的影响及其可能的作用机制。方法:应用CCK-8法检测HHT联合IM对K562/G01细胞增殖的影响,流式细胞术检测细胞的凋亡率及磷酸化酪氨酸水平,Western blot检测P210及PI3K/Akt信号通路相关蛋白的表达水平。结果:HHT联合IM与单药相比,对K562/G01细胞的增殖活性具有明显抑制作用(P0.05),细胞的凋亡率显著增加(P0.05);HHT与IM联合可显著抑制K562/G01细胞内的p-Tyr及p-Crkl的表达水平,并能使p210蛋白及其下游通路蛋白P13K和p-Akt的表达水平明显降低。结论:HHT联合IM可协同抑制K562/G01细胞增殖并诱导其凋亡,其机制可能与抑制p210蛋白表达及其激酶活性有关。     

酪氨酸激酶抑制剂STI571与P21WAF基因克隆治疗慢性粒细胞白血病的实验研究

本研究探讨酪氨酸激酶抑制剂ST1571和P21^WAF基因克隆对慢性粒细胞白血病急变K562细胞株的细胞增殖、细胞周期及凋亡等的治疗作用。RT—PCR扩增P21^WAF基因，胶纯化回收后连接到T载体测序，序列正确后构建P21—pcDNA3．1栽体，将P21—pcDNA3．1与空载体分别以脂质体转染入P21蛋白表达缺如的K562细胞，经筛选得到G418抗性的K562细胞株，Westernblot证实转染后有P21蛋白表达，MTT法检测细胞存活率，流式细胞仪检测细胞周期和凋亡。结果表明：表达外源性P21蛋白的P21—pcDNA3．1-K562细胞株生长速度明显慢于对照K562细胞株，流式细胞仪显示G0／G1期细胞增多，MTT法显示P21—pcDNA3．1-K562细胞与ST1571联合应用后，与单用ST1571作用的K562细胞相比，凋亡细胞比例轻度减少，细胞存活率下降较慢。结论：表达外源P21蛋白能抑制K562细胞增殖，同时对ST1571的促凋亡作用有轻度抑制，并降低K562细胞对ST1571的敏感性。     

Molecular targets for apigenin-induced cell cycle arrest and apoptosis in prostate cancer cell xenograft

Apigenin (4',5,7-trihydroxyflavone) is a promising chemopreventive agent abundantly present in fruits and vegetables that has been shown to promote cell cycle arrest and apoptosis in various malignant cell lines. To determine whether pharmacologic intervention with apigenin has a direct growth inhibitory effect on human prostate tumors implanted in athymic nude mice, we examined cell cycle regulatory molecules as precise molecular targets of apigenin action. Apigenin feeding by gavage to these mice at doses of 20 and 50 microg/mouse/d in 0.2 mL of a vehicle containing 0.5% methyl cellulose and 0.025% Tween 20 resulted in significant decreases in tumor volume and mass of androgen-sensitive 22Rv1 and androgen-insensitive PC-3-implanted cells. Oral intake of apigenin resulted in dose-dependent (a) increase in the protein expression of WAF1/p21, KIP1/p27, INK4a/p16, and INK4c/p18; (b) down-modulation of the protein expression of cyclins D1, D2, and E; and cyclin-dependent kinases (cdk), cdk2, cdk4, and cdk6; (c) decrease in retinoblastoma phosphorylation at serine 780; (d) increase in the binding of cyclin D1 toward WAF1/p21 and KIP1/p27; and (e) decrease in the binding of cyclin E toward cdk2 in both types of tumors. In addition, apigenin feeding resulted in stabilization of p53 by phosphorylation at serine 15 in 22Rv1 tumors, which seems to exhibit p53-dependent growth inhibitory responses. Apigenin intake by these mice also resulted in induction of apoptosis, which positively correlated with serum and tumor apigenin levels. Taken together, this is the first systematic in vivo study showing the involvement of cell cycle regulatory proteins as potential molecular targets of apigenin.     

转染p21WAF1基因降低K562细胞对VP-16的敏感性

为探讨p21^WAF1对K562细胞药物敏感性的谳节作用及其对VP－16诱导的K562细胞凋亡的影响，构建了p21^WAF1逆转录病毒表达载体，体外转染白血病细胞系K562。经RT－PCR和Western印亦检测得到稳定表达p21^WAF1的K562－p21^WAF1细胞克隆后，用MTT法和存活细胞计数法检测转染p21^WAF1的K562细胞对VP－16在剂量和作用时间上的敏感性变化，用DNA凋亡片段分析和流式细胞术检测其对VP－16诱导的K562细胞凋亡的影响。实验结果显示，外源性p21^WAF1的表达明显降低了VP－16诱导的K562细胞凋亡，降低了K562细胞对VP－16的敏感性。以上结果表明，p21^WAF1能通过抑制K562细胞的凋亡来降低其对VP－16的敏感性。     

YC-1 [3-(5'-Hydroxymethyl-2'-furyl)-1-benzyl Indazole] exhibits a novel antiproliferative effect and arrests the cell cycle in G0-G1 in human hepatocellular carcinoma cells

This study delineates the antiproliferative activities and in vivo efficacy of YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole] in human hepatocellular carcinoma cells. YC-1 inhibited the growth of HA22T and Hep3B cells in a concentration-dependent manner without significant cytotoxicity. YC-1 induced G(1) phase arrest in the cell cycle, as detected by an increase in the proportion of cells in the G(1) phase using FAC-Scan flow cytometric analysis. It was further shown that cGMP, p42/p44 mitogen-activated protein kinase, or AKT kinase-mediated signaling pathways did not contribute to the YC-1-induced effect. Of note, YC-1 induced a dramatic increase in the expression of cyclin-dependent kinase (CDK)-inhibitory protein, p21(CIP1/WAP1), and a modest increase in p27(KIP1). The association of p21(CIP1/WAP1) with CDK2 was markedly increased in cells responsive to YC-1. YC-1 did not modify the expression of cyclin D1, cyclin E, CDK2, or CDK4. In a corollary in vivo study, YC-1 induced dose-dependent inhibition of tumor growth in mice inoculated with HA22T cells. Immunohistochemical analysis revealed an inverse relationship between the staining of p21(CIP1/WAF) and the staining of Ki-67, a cell proliferation marker. Based on the results reported herein, we suggest that YC-1 induces cell cycle arrest and inhibits tumor growth both in vitro and in vivo via the up-regulation of p21(CIP1/WAP1) expression in HA22T cells. Because of this, YC-1 is a potential antitumor agent worthy of further investigation.     

Perifosine, a novel alkylphospholipid, inhibits protein kinase B activation

Perifosine is a novel p.o. bioavailable alkylphospholipid. Perifosine has displayed significant antiproliferative activity in vitro and in vivo in several human tumor model systems and has recently entered phase I clinical trials. Recent studies have identified that perifosine could cause cell cycle arrest with induction of p21(WAF1/CIP1) in a p53-independent fashion; however, the basis for that effect is not known. Structurally, perifosine resembles naturally occurring phospholipids. Therefore, we hypothesized that perifosine might perturb pathways related to phospholipids modulated by growth factor action. We demonstrate here that perifosine causes dose-dependent inhibition of protein kinase B/Akt phosphorylation and thus activation at concentrations causing growth inhibition of PC-3 prostate carcinoma cells. Only the myristoylated form of Akt (MYR-Akt), which bypasses the requirement for pleckstrin homology (PH) domain-mediated membrane recruitment, abrogated perifosine-mediated decrease of Akt phosphorylation and cell growth inhibition by perifosine. We demonstrate further that perifosine decreases the plasma membrane localization of Akt, and this is substantially relieved by MYR-Akt along with relief of downstream drug effect on induction of p21(WAF1/CIP1). Perifosine does not directly affect phosphoinositide 3-kinase (PI3K), phosphoinositide-dependent kinase 1, or Akt activity at concentrations inhibiting Akt phosphorylation and membrane localization. Our results demonstrate that Akt is an important cellular target of perifosine action. In addition, these studies show that the membrane translocation of certain PH domain-containing molecules can be greatly perturbed by the alkylphospholipid class of drugs and imply further that the PI3K/Akt pathway contributes to regulation of p21(WAF1/CIP1) expression.