PAI-1过表达促进食管鳞癌细胞的侵袭和迁移

食管癌是常见的恶性肿瘤之一。由SERPINE1基因编码的纤溶酶原激活物抑制因子1(plasminogen activator inhibitor-1,PAI-1)已被报道在多种类型癌症患者的肿瘤组织中存在高表达并参与癌症进展。为探讨PAI-1蛋白在食管鳞癌中的作用及其分子机制,本研究首先利用Westernblot实验和酶联免疫吸附实验(enzyme linked immunosorbent assay, ELISA)检测各食管鳞癌细胞系中PAI-1的表达和分泌水平,结果显示,PAI-1高表达的食管鳞癌细胞系分泌至细胞外的PAI-1水平相对较高。进一步选取PAI-1表达及分泌水平均较高的KYSE150和KYSE450细胞系作为研究模型,通过si RNA(小干扰RNA)瞬时转染和Transwell实验证实敲降SERPINE1可显著抑制食管鳞癌KYSE150和KYSE450细胞的侵袭和迁移。同时,构建了慢病毒介导的SERPINE1稳定敲降细胞株KYSE150和KYSE450,将SERPINE1稳定敲降的细胞培养基中外源加入PAI-1蛋白进行Transwell回复实验,结果表明PAI-1过表达可增强食管鳞癌细胞的侵袭和迁移能力。体内实验结果显示,降低PAI-1表达可显著抑制食管鳞癌细胞的成瘤和肺转移能力。分子水平检测表明PAI-1过表达可激活AKT和ERK信号通路,免疫共沉淀(co-immunoprecipitation,Co-IP)实验结果进一步显示PAI-1可能与膜受体LRP1(LDLreceptor related protein1)存在相互作用。上述研究结果表明,PAI-1可能通过与LRP1相互作用进而促进食管鳞癌细胞的侵袭和迁移。     

microRNA-21在食管癌细胞增殖、迁移和凋亡中的作用

本研究检测了40例食管癌组织和40例癌旁组织中的miR-21、PTEN、PI3K和AKT表达,并通过转染miR-21抑制剂来敲低人食管癌细胞系EC9706的miR-21表达,考察了miR-21对食管癌细胞生长的影响。研究发现,食管癌组织中PTEN蛋白的阳性染色评分低于癌旁组织(p<0.05),而PI3K和AKT蛋白的阳性染色评分高于癌旁组织(p<0.05)。miR-21在人食管癌组织中被上调(3.56 vs 1.21,p<0.05)。转染miR-21抑制剂导致PTEN蛋白表达升高,而PI3K和AKT蛋白表达降低(p<0.05)。转染miR-21抑制剂抑制了EC9706细胞的增殖和迁移,但促进了细胞凋亡(p<0.05)。miR-21的上调可通过激活PTEN/PI3K/AKT信号通路来促进食道癌细胞的增殖和迁移,并抑制细胞凋亡。     

血清应答因子在食管鳞癌细胞侵袭转移中的作用

目的:研究血清应答因子(serum response factor,SRF)在人食管鳞癌细胞体外侵袭转移中的意义。方法:选用EC9706-H、EC9706-L和EC109-H、EC109-L两对高低转移细胞系,采用细胞划痕实验验证食管鳞癌高低转移细胞系体外侵袭转移能力的差异;Western blot检测SRF在两对食管鳞癌高低转移细胞系中的差异表达;在EC9706-H、EC109-H细胞中加入CCG(SRF抑制剂)抑制SRF的表达后,检测其侵袭转移能力的变化。结果:细胞划痕实验验证了两对食管鳞癌高低转移细胞系侵袭转移能力的差异;Western blot结果提示SRF在EC9706-H、EC109-H细胞中的表达水平显著高于EC9706-L、EC109-L细胞;在EC9706-H、EC109-H细胞中加入CCG抑制SRF的表达后,其侵袭转移能力明显减退。结论:SRF在高转移性食管鳞癌细胞系中呈现高表达,在低转移性食管鳞癌细胞系中呈现低表达,抑制高转移性食管鳞癌细胞系中SRF的表达后,其侵袭转移能力下降,提示SRF和食管鳞癌的侵袭转移能力呈正相关。     

Rho GTPases对肿瘤血管生成相关分子的作用

探讨RhoGTPases的 3个主要分子RhoA、Rac1和Cdc4 2对肿瘤血管生成相关分子的作用 .构建负显性RhoA、Rac1和Cdc4 2的真核表达质粒 ,在Lipofectamine2 0 0 0 介导下转染胃癌细胞AGS ,应用ELISA检测细胞培养上清中VEGF的含量 ,应用Western印迹检测肿瘤血管生成相关分子HIF 1α、P5 3和PTEN的表达水平 .成功地构建了负显性RhoA、Rac1和Cdc4 2的真核表达质粒 ,转染胃癌细胞AGS并经G4 18筛选出单克隆 .ELISA表明转染细胞培养上清中VEGF的含量可被明显抑制 ;Western印迹表明 ,负显性RhoGTPases在蛋白水平上可下调HIF 1α表达水平 ,上调P5 3的表达水平 .结果表明 ,Rho家族的 3个主要分子可能通过调节血管生成相关分子的表达来促进肿瘤血管生成 .     

PI3K/AKT 通路参与调控乳腺癌多药耐药和侵袭转移的研究

目的:探讨磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(phosphatidylinositol 3 kinase/serine-threonine kinase,PI3K/AKT)信号通路与乳腺癌多药耐药和侵袭转移的相关性。方法:以乳腺癌细胞系MCF-7为母本,持续低浓度加药诱导建立阿霉素(Adriamycin,ADR)耐药系MCF-7/ADR’。细胞免疫荧光检测两细胞系中磷酸化AKT(phosphorylated AKT,P-AKT)、P-糖蛋白(P-Glycoprotein,P-gp)、基质金属蛋白酶2(matrix metalloproteinase-2,MMP-2)的表达。PI3K抑制剂LY294002作用两系前后,Western Blot检测P-AKT、MMP-2、P-gp的表达改变及qRT-PCR检测MMP-2、MDR1的表达改变。结果:P-AKT、P-gp(MDR1)、MMP-2在MCF-7中为低表达或不表达,MCF-7/ADR’中为高表达。LY294002作用两系后,P-AKT、P-gp(MDR1)、MMP-2在MCF-7/ADR’中的表达明显减低(P<0.05),MCF-7无明显改变。结论:抑制PI3K/AKT信号通路可有效降低MCF-7/ADR’耐药和侵袭转移能力,PI3K/AKT通路是调控乳腺癌多药耐药和侵袭转移的重要信号通路之一。     

RhoGDI2与PI3K/Akt/mTOR信号通路在肺癌细胞中的相关性研究

目的探讨肿瘤转移相关因子RhoGDI2与PI3K/Akt/mTOR信号通路在肺癌侵袭转移过程中的作用及相关机制。方法利用PI3K/Akt/mTOR信号通路上特异性的抑制剂,采用MTT法,伤口愈合实验及侵袭实验观察不同浓度药物对肺癌95D细胞生长侵袭转移能力的影响,通过Western Blot方法观察RhoGDI2蛋白水平的变化。结果PI3K抑制剂LY294002及mTOR抑制剂Rapamycin都能抑制肺癌细胞95D的侵袭转移能力,联合应用抑制作用更强。PI3K抑制剂LY294002处理组RhoGDI2蛋白的表达量增加,且随浓度增加RhoGDI2蛋白表达也增加。mTOR抑制剂Rapamycin组,在低浓度时增加RhoGDI2蛋白的表达,但增大Rapamycin的浓度,RhoGDI2蛋白的表达反而降低。低浓度LY294002组和Rapa-mycin组联合应用可以明显增加RhoGDI2蛋白的表达。结论PI3K/Akt/mTOR信号通路中Akt的活化与RhoGDI2密切相关,RhoGDI2可能直接或间接通过与Akt的相互作用参与调节肺癌的侵袭转移的过程。     

SKA1通过Cdc42介导高尔基体堆叠调控胰腺癌细胞侵袭与转移

目的：探讨SKA1调控胰腺导管腺癌（PDAC）侵袭与转移的分子机制。方法：利用免疫组化染色法检测胰腺导管腺癌组织样本及癌旁组织中SKA1与下游分子Cdc42的表达水平、用免疫印迹方法在不同胰腺癌细胞系及正常胰腺导管上皮细胞中进行验证;利用慢病毒转染技术构建SKA1稳定敲减和过表达的胰腺癌细胞株;利用免疫荧光方法检测PDAC细胞内SKA1敲低或过表达对高尔基体结构的影响,及Cdc42抑制剂ZCL278对高尔基体结构变化的调控;并利用Transwell实验及细胞划痕实验检测ZCL278对SKA1促癌作用的影响;应用免疫印迹方法检测SKA1及Cdc42表达对自噬标志物的影响。结果：在胰腺导管腺癌组织与细胞中SKA1与Cdc42表达均显著高于正常组织或细胞,且二者表达呈显著正相关;并且发现SKA1低表达的患者具有更长的总体生存期,而Cdc42表达高低与总体生存期无关。接着我们发现SKA1可促进PDAC细胞内高尔基体堆叠,并且在SKA1过表达的细胞中Cdc42抑制剂ZCL278可以抑制这种堆叠现象。进一步我们发现抑制Cdc42可逆转SKA1过表达对胰腺癌侵袭与转移的促进效应,具有统计学差异,而在...     

TPST1表达在CXCR4诱导的乳腺癌细胞侵袭中的作用研究

C-X-C趋化因子受体4(CXCR4)是乳腺癌细胞运动的关键调节因子。CXCR4的功能性表达与乳腺癌的恶性进展密切相关。酪氨酸硫酸化转移酶1(tyrosylprotein sulfotransferase 1,TPST1)是CXCR4蛋白翻译后酪氨酸硫酸化修饰的一个关键酶。本研究将探索TPST1在CXCR4调节乳腺癌细胞侵袭过程中的作用机制。利用定量PCR,免疫组织化学和蛋白质免疫印迹等试验技术检测乳腺癌组织和细胞系中CXCR4和TPST1的mRNA和蛋白表达水平。RNA干扰,趋化试验和侵袭试验用于检测TPST1对于CXCR4诱导的乳腺癌细胞侵袭的影响。研究发现CXCR4蛋白在乳腺癌转移淋巴结组织中呈高表达(P=0. 0016)。CXCR4在乳腺癌转移淋巴结组织中的高表达与肿瘤浸润深度密切相关(P=0. 026)。TPST1与CXCR4蛋白表达在乳腺癌原发组织和配对转移淋巴结组织中均呈显著正相关(P=0. 009; P=0. 006)。TPST1在高度恶性乳腺癌MDA-MB-231细胞中呈高表达,在低度恶性乳腺癌MCF-7细胞中弱表达,而两者CXCR4表达基本相同。小RNA干扰降低TPST1的表达后,下调了乳腺癌MDA-MB-231细胞对于CXCR4配体即基质细胞衍生因子1α(stromal cell-derived factor 1 alpha,SDF-1α)的运动反应性,进而降低CXCR4诱导的MDA-MB-231细胞迁移和侵袭能力。综上,在CXCR4诱导的乳腺癌细胞侵袭过程中,TPST1表达对于CXCR4功能性活化至关重要,TPST1可能作为潜在的抗CXCR4药物治疗乳腺癌恶性进展的联合靶点。     

紫杉醇促进食管癌细胞焦亡的机制

[目的]探讨紫杉醇促进食管癌细胞焦亡的潜在机制。[方法]用紫杉醇处理后,检测食管癌细胞CaES-17、TE-1、TE-10、TE-11、NEC的凋亡水平和坏死水平,检测食管癌细胞中Casp1+/SYTOX+细胞比例、LDH释放水平、IL-18和IL-1β分泌水平,检测食管癌细胞Pro-Casp4、Casp4、Pro-Casp5、Casp5、GSDMD-FL、GSDMD、Pro-Casp1、Casp1-p20、NALP1、NLRP3、AIM2、NLRC4和ASC的表达水平。通过分子对接模拟紫杉醇与NLRP3的泛素E3酶TRIM31的相互作用。[结果]紫杉醇处理后,食管癌细胞的凋亡水平和坏死水平上升,Casp1+/SYTOX+细胞比例上升,LDH释放增多,IL-18和IL-1β分泌增多。紫杉醇处理后,Pro-Casp1、Casp1-p20、NLRP3的表达水平显著上升,AIM2、NLRC4和ASC的表达水平显著下降。敲低TRIM31并用紫杉醇处理后,食管癌细胞的焦亡水平显著降低。通过分子对接发现紫杉醇与TRIM31存在潜在的结合,结合位点为Y375、S417、N443。[结论]紫杉醇通过结合NLRP3的泛素E3连接酶TRIM31抑制了NLRP3的降解,激活了Caspase1/GSDMD,促就了食管癌细胞发生焦亡。     

Rho GTPases与肿瘤

Rho GTPases参与调控细胞的多种关键生物学行为,特别是细胞的生长、细胞骨架的形成、转录调节等生物学过程. 在肿瘤的发生发展中Rho GTPases也扮演了重要的角色．本文将回顾Rho GTPases的调控（包括经典及非经典调控方式）及其关键成员（RhoA、Cdc42及Rac1）与临床肿瘤的研究进展,特别是它们参与调控肿瘤的增殖、迁移、侵袭、凋亡等恶性生物学行为,从而为研发靶向Rho GTPases的小分子/基因药物了奠定基础．     

RhoA/ROCK-mediated switching between Cdc42- and Rac1-dependent protrusion in MTLn3 carcinoma cells

Rho GTPases are versatile regulators of cell shape that act on the actin cytoskeleton. Studies using Rho GTPase mutants have shown that, in some cells, Rac1 and Cdc42 regulate the formation of lamellipodia and filopodia, respectively at the leading edge, whereas RhoA mediates contraction at the rear of moving cells. However, recent reports have described a zone of RhoA/ROCK activation at the front of cells undergoing motility. In this study, we use a FRET-based RhoA biosensor to show that RhoA activation localizes to the leading edge of EGF-stimulated cells. Inhibition of Rho or ROCK enhanced protrusion, yet markedly inhibited cell motility; these changes correlated with a marked activation of Rac-1 at the cell edge. Surprisingly, whereas EGF-stimulated protrusion in control MTLn3 cells is Rac-independent and Cdc42-dependent, the opposite pattern is observed in MTLn3 cells after inhibition of ROCK. Thus, Rho and ROCK suppress Rac-1 activation at the leading edge, and inhibition of ROCK causes a switch between Cdc42 and Rac-1 as the dominant Rho GTPase driving protrusion in carcinoma cells. These data describe a novel role for Rho in coordinating signaling by Rac and Cdc42.     

HGF-induced PKCζ activation increases functional CXCR4 expression in human breast cancer cells

The chemokine receptor CXCR4 and its ligand CXCL12 have been shown to mediate the metastasis of many malignant tumors including breast carcinoma. Interaction between hepatocyte growth factor (HGF) and the Met receptor tyrosine kinase mediates development and progression of cancers. HGF is able to induce CXCR4 expression and contributes to tumor cell invasiveness in breast carcinoma. However, the mechanism of the CXCR4 expression modulated by c-Met-HGF axis to enhance the metastatic behavior of breast cancer cells is still unclear. In this study, we found that HGF induced functional CXCR4 receptor expression in breast cancer cells. The effect of HGF was specifically mediated by PKCζ activity. After transfection with PKCζ-siRNA, the phosphorylation of PKCζ and CXCR4 was abrogated in breast cancer cells. Interference with the activation of Rac1, a downstream target of HGF, prevented the HGF-induced increase in PKCζ activity and CXCR4 levels. The HGF-induced, LY294002-sensitive translocation of PKCζ from cytosol to plasma membrane indicated that HGF was capable of activating PKCζ, probably via phosphoinositide (PI) 3-kinases. HGF treatment also increased MT1-MMP secretion. Inhibition of PKCζ, Rac-1 and phosphatidylinositol 3-kinase may attenuate MT1-MMP expression in cells exposed to HGF. Functional manifestation of the effects of HGF revealed an increased ability for migration, chemotaxis and metastasis in MDA-MB-436 cells in vitro and in vivo. Our findings thus provided evidence that the process of HGF-induced functional CXCR4 expression may involve PI 3-kinase and atypical PKCζ. Moreover, HGF may promote the invasiveness and metastasis of breast tumor xenografts in BALB/c-nu mice via the PKCζ-mediated pathway, while suppression of PKCζ by RNA interference may abrogate cancer cell spreading.     

Small GTPase protein Rac-1 is activated with maturation and regulates cell morphology and function in chondrocytes

During maturation, chondrocytes undergo changes in morphology, matrix production, and gene expression; however, it remains unclear whether these are interrelated. In this study, we examined whether Rho GTPases were involved in these regulatory interplays. Levels of active Rho GTPases were assayed in immature and mature primary chondrocytes. We found that activation of Rac-1 and Cdc42 increased with maturation, whereas RhoA levels remained unchanged. GFP-tagged Rho GTPases tracked cellular localization. Rac-1 was enriched at the cell membrane where it co-localized with cortical actin, while RhoA and Cdc42 were cytoplasmic. To test the roles of Rac-1 in chondrocyte maturation, we force-expressed constitutively active or dominant negative forms of Rac-1 and assessed phenotypic consequences in primary chondrocytes. Activated Rac-1 expression induced chondrocyte enlargement and increased matrix metalloproteinase expression, which are characteristic of mature chondrocytes. Conversely, Rac-1 inactivation diminished adhesion, decreased alkaline phosphatase activity, and stimulated functions typical of immature chondrocytes. Exposure to a pro-maturation factor, Wnt3A, induced a flattened and enlarged morphology accompanied by peripheral Rac-1 re-arrangement. Wnt3A stimulated Tiam1 expression and Rac-1 activation, while DN-Rac-1 inhibited Wnt3A-induced cell spreading. Our data provide strong evidence that Rac-1 coordinates changes in chondrocyte phenotype and function and stimulates the maturation process essential for skeletal development.     

Activated Rac1 selectively up-regulates the expression of integrin alpha6beta4 and induces cell adhesion and membrane ruffles of nonadherent colon cancer Colo201 cells

Functions of small GTPases in integrin expression were investigated when the interaction of nonadherent human colon carcinoma 201 cells with the extracellular matrix (ECM) was examined. By transfection of the constitutively active form of a small GTPase Rac1, Rac V12, adhesion of cells to the ECM increased with concomitant cell spreading and formation of membrane ruffles. Activated Cdc42 and Cdc42 V12, but not wild-type Rac1, Cdc42, or RhoA, also induced the adhesion and spreading of Colo201 cells. This adhesion is integrin beta4 dependent since an antibody for integrin beta4 inhibited the RacV12-dependent cell adhesion and numbers of adhesive cells on laminin-coated plates exceeded those on collagen- and fibronectin-coated plates. By immunofluorescence, in addition to clustering of integrin molecules, expression of integrin alpha6beta4 on the cell surface of Rac V12- and Cdc42 V12-expressing cells was selectively up-regulated without an increase in biosynthesis of alpha6beta4 integrin. Treatment of Rac V12-expressing cells with wortmannin or LY294002, specific inhibitors of phosphoinositide 3-OH kinase, decreased the up-regulated alpha6beta4 and cell adhesion. In light of this evidence, we propose that the regulation of integrin alpha6beta4 expression induced by Rac1 and Cdc42 may play an important role in cell adhesion and tumorigenesis of colon carcinoma cells.     

Id-1 induces cell invasiveness in immortalized epithelial cells by regulating cadherin switching and Rho GTPases

Epithelial-mesenchymal transition (EMT), characterized by cadherin switching, contributes to cancer metastasis. Our recent study showed that Id-1 (inhibitor of differentiation-1) promotes metastasis in esophageal cancer cells, but whether the invasive and metastatic dynamics can be induced early in the carcinogenesis process is still unclear. Immortalization is regarded as the initial stage in the malignant transformation of normal cells. In this study, we investigated the role and mechanisms of Id-1 in inducing EMT and cell invasiveness in immortalized esophageal epithelial cells. We found that immortalized epithelial cells expressed higher endogenous levels of Id-1 compared with normal cells. Ectopic Id-1 expression inhibited the differentiation of immortalized esophageal epithelial cells and promoted cadherin switching, which was accompanied by increased adhesiveness to extracellular matrix, cell motility, migratory potential and matrix metalloproteinase-dependent invasiveness. GTPase activity assays showed that over-expression or short-hairpin RNA knockdown of Id-1 led to corresponding changes in Rac1 activity, whereas RhoA activity was significantly decreased with Id-1 depletion. Inhibitors targeting Rac1, RhoA, and Rho kinase suppressed the invasiveness of Id-1-expressing NE2-hTERT cells. Knockdown of N-cadherin in Id-1-over-expressing cells inhibited cell invasiveness and down-regulated RhoA activity. These data suggest that the Id-1-induced invasive potential may be regulated through the N-cadherin-RhoA axis and Rac1 activation.     

Simvastatin improves the homing of BMSCs via the PI3K/AKT/miR‐9 pathway

Bone marrow‐derived mesenchymal stem cells (BMSCs) have great therapeutic potential for many diseases. However, the homing of BMSCs to injury sites remains a difficult problem. Recent evidence indicates that simvastatin stimulates AKT phosphorylation, and p‐AKT affects the expression of chemokine (CXC motif) receptor‐4 (CXCR4). Therefore, simvastatin may improve the expression of CXCR4 in BMSCs, and microRNAs (miRs) may participate in this process. In this study, we demonstrated that simvastatin increased both the total and the surface expression of CXCR4 in BMSCs. Stromal cell‐derived factor‐1α (SDF?1α)‐induced migration of BMSCs was also enhanced by simvastatin, and this action was inhibited by AMD 3100(a chemokine receptor antagonist for CXCR4). The PI3K/AKT pathway was activated by simvastatin in this process, and LY294002 reversed the overexpression of CXCR4 caused by simvastatin. MiR‐9 directly targeted CXCR4 in rat BMSCs, and simvastatin decreased miR‐9 expression. P‐AKT affected the expression of miR‐9; as the phosphorylation of AKT increased, miR‐9 expression decreased. In addition, LY294002 increased miR‐9 expression. Taken together, our results indicated that simvastatin improved the migration of BMSCs via the PI3K/AKT pathway. MiR‐9 also participated in this process, and the phosphorylation of AKT affected miR‐9 expression, suggesting that simvastatin might have beneficial effects in stem cell therapy.     

Inhibition of chemokine (CXC motif) ligand 12/chemokine (CXC motif) receptor 4 axis (CXCL12/CXCR4)-mediated cell migration by targeting mammalian target of rapamycin (mTOR) pathway in human gastric carcinoma cells

CXCL12/CXCR4 plays an important role in metastasis of gastric carcinoma. Rapamycin has been reported to inhibit migration of gastric cancer cells. However, the role of mTOR pathway in CXCL12/CXCR4-mediated cell migration and the potential of drugs targeting PI3K/mTOR pathway remains unelucidated. We found that CXCL12 activated PI3K/Akt/mTOR pathway in MKN-45 cells. Stimulating CHO-K1 cells expressing pEGFP-C1-Grp1-PH fusion protein with CXCL12 resulted in generation of phosphatidylinositol (3,4,5)-triphosphate, which provided direct evidence of activating PI3K by CXCL12. Down-regulation of p110β by siRNA but not p110α blocked phosphorylation of Akt and S6K1 induced by CXCL12. Consistently, p110β-specific inhibitor blocked the CXCL12-activated PI3K/Akt/mTOR pathway. Moreover, CXCR4 immunoprecipitated by anti-p110β antibody increased after CXCL12 stimulation and G(i) protein inhibitor pertussis toxin abrogated CXCL12-induced activation of PI3K. Further studies demonstrated that inhibitors targeting the PI3K/mTOR pathway significantly blocked the chemotactic responses of MKN-45 cells triggered by CXCL12, which might be attributed primarily to inhibition of mTORC1 and related to prevention of F-actin reorganization as well as down-regulation of active RhoA, Rac1, and Cdc42. Furthermore, rapamycin inhibited the secretion of CXCL12 and the expression of CXCR4, which might form a positive feedback loop to further abolish upstream signaling leading to cell migration. Finally, we found cells expressing high levels of cxcl12 were sensitive to rapamycin in its activity inhibiting migration as well as proliferation. In summary, we found that the mTOR pathway played an important role in CXCL12/CXCR4-mediated cell migration and proposed that drugs targeting the mTOR pathway may be used for the therapy of metastatic gastric cancer expressing high levels of cxcl12.