RhoB对胃癌细胞SGC7901的负性调控作用

目的研究RhoB对胃癌细胞SGC7901增殖调控作用。方法用PCR扩增出RhoB的全长cDNA，构建RhoB可诱导表达载体pGene／V5-His-RhoB；脂质体介导法将调控载体pSwitch及诱导表达载体pGene／V5-His-RhoB先后转入人胃癌细胞SGC7901中，筛选出稳定抗性克隆；Western blot检测米非斯酮诱导后转染细胞中RhoB蛋白的表达。用MTT assay检测RhoB转染细胞株的生长速度、双苯并咪唑染料(Hoechst 33258)活细胞吸收分析法、流式细胞仪(FCM)检测RhoB对胃癌细胞凋亡指数作用。结果成功构建RhoB可诱导真核表达载体pGene／V5-His-RhoB，并经酶切和测序鉴定；转染后经潮霉素B和Zeocin筛选出稳定抗性克隆SGC7901／RhoB；米非斯酮诱导出RhoB蛋白表达，在诱导24小时后蛋白表达最高；细胞增殖试验结果显示，RhoB表达上调后胃癌细胞增殖受到抑制；细胞凋亡检测提示高表达RhoB可明显诱导胃癌细胞凋亡。结论RhoB对胃癌细胞增殖具有负性调控作用，可诱导胃癌细胞出现凋亡。     

RhoC小干扰RNA抑制胃癌细胞的迁移和侵袭

目的：研究Ras homologyC（RhoC）在胃癌转移中的作用。方法：利用Vector NTI软件设计并构建RhoC的小干扰RNA（siRNA）载体，利用脂质体介导法将一组RhoCsiRNA分别转染胃癌SGC7901细胞。筛选出稳定抗性克隆；Westernblot检测RhoCsiRNA转染后的抑制效应，Cell Counting Kit-8检测RhoC siRNA转染细胞株的生长速度；MTT法检测转染细胞株对化疗药物的敏感性；损伤刮擦实验和TRANSWELL小室实验分别检测转染细胞株的迁移与侵袭能力。结果：在计算机辅助下成功地设计并构建了5个RhoC的小干扰RNA载体，Western blot显示其中一个RhoC的小干扰RNA RhloC-s362对RhoC的表达有明显的抑制作用；尽管下调RhoC的表达对胃癌细胞的生长和药物敏感性元明显影响，但可显著抑制肿瘤细胞的迁移与侵袭。结论：RhoC siRNARhoC-s362能够明显抑制胃癌SGC7901细胞中RhoC的表达，并进而抑制胃癌细胞的迁移与侵袭，提示RhoC可能在胃癌转移中发挥重要作用。     

RhoA小干扰RNA对胃癌AGS细胞基因表达谱的影响

目的:应用RhoA小干扰RNA(small interfering RNA,siRNA)转染胃癌细胞系AGS细胞,采用高通量基因芯片技术,筛选基因表达谱的变化,为进一步研究RhoA信号转导通路奠定基础.方法:用pSilencer3.1载体构建RhoA/siRNA重组质粒.Effectene转染试剂转染AGS细胞,空载体pSilencer3.1转染对照组.应用G418筛选转染细胞系,获得稳定转染细胞;美国Agilent基因芯片检测细胞基因表达谱变化.结果:基因芯片检测全基因组,发现表达上调的有1151个基因,表达下调的有1079个基因,涉及信号转导、细胞周期、细胞凋亡等相关信号分子.生物信息学分析显示,与细胞凋亡有关的caspase家族,以及细胞周期调控基因存在明显的差异表达.结论:基因芯片结果提示干扰RhoA表达后,与凋亡和增殖有关的分子在RhoA介导的肿瘤细胞异常增殖信号转导中起着重要的调控作用,为下一步研究其信号调控网络机制提供重要的信息.     

层黏连蛋白受体参与缺氧诱导胃癌多药耐药的机制研究

目的:研究缺氧对胃癌细胞对于化疗药物敏感性的影响以及层黏连蛋白受体在缺氧诱导的胃癌MDR中的作用和分子机制。方法:MTT比色法、Annexin V/PI染色法和阿霉素的蓄积和潴留实验检测胃癌细胞在缺氧和常氧状态下对化疗药物敏感性的差异;Western blot和半定量RT-PCR检测缺氧条件下胃癌细胞中67Kda层黏连蛋白受体(67Kda laminin receptor,67LR)的表达;Western blot、半定量RT-PCR方法检测缺氧条件下胃癌细胞系SGC7901中67LR的表达和活性;利用siRNA干涉67LR的表达,MTT比色法、AnnexinV/PI染色法检测缺氧条件下调下胃癌细胞系67LR的表达对化疗药物敏感性的影响。结果:缺氧能够显著降低胃癌细胞对化疗药物的敏感性,以及化疗药物诱导的凋亡和药物在细胞内的潴留和蓄积;缺氧能够显著上调67LR的表达和转录活性;67LR siRNA能够抑制LR的表达;抑制67LR的表达能够显著逆转缺氧诱导的胃癌的MDR表型。结论:缺氧能够增加胃癌细胞对于化疗药物的抵抗,通过上调67LR表达,加剧了缺氧诱导的胃癌多药耐药表型,抑制67LR的表达能够逆转缺氧诱导的胃癌多药耐药的发生。     

靶向抑制COX-2基因对胃癌细胞BGC823凋亡及药物敏感性的影响

目的:研究siRNA靶向抑制环氧合酶-2(COX-2)基因后对胃癌细胞BGC823增殖、凋亡及药物敏感性的影响.方法:将COX-2 siRNA(siRNA-COX-2组)及negative control siRNA(siRNA-control组)序列转入细胞BGC823中,检测细胞增殖能力,观察多西紫杉醇(docetaxel艾素)、奥沙利铂(L-OHP)、5-氟尿嘧啶(5-FU)的药物敏感性变化,及转染前后BGC823细胞COX-2、β-catenin、Bcl-2 mRNA基因和蛋白的表达.结果:siRNA-COX-2组细胞在转染后第四天开始增殖能力下降,与siRNA-control组差异存在明显统计学意义(P＜0.05),而siRNA-control组细胞于BGC823组增殖能力差异无明显统计学意义(P＞0.05).MTT法检测转染后胃癌细胞对艾素、奥沙利铂、5-氟尿嘧啶的IC50较转染前药物敏感性明显增加.流式细胞术检测转染前后胃癌细胞凋亡率为(3.08％±0.27％vs 16.14％ ±1.89％,P＜0.05),转染后凋亡明显增加(P＜0.05).qRT-PCR法检测发现转染后COX-2、β-catenin、Bcl-2 mRNA基因的表达明显下降,Westernblot检测发现,转染后48小时COX-2蛋白表达达到最低,转染后48小时β-catenin、Bcl-2蛋白表达明显下降(P＜0.05).结论:通过下调COX-2基因的表达,可有效抑制WNT信号通路的激活,同时有效降低Bcl-2基因的表达.抑制COX-2基因后可有效降低胃癌细胞BGC823的细胞增殖能力,可有效提高对艾素、奥沙利铂、5-氟尿嘧啶的药物敏感性,有效促进细胞凋亡.     

RhoA小干扰RNA对胃癌AGS细胞基因表达谱的影响

目的：应用RhoA小干扰RNA（small interfering RNA，siRNA）转染胃癌细胞系AGS细胞，采用高通量基因芯片技术，筛选基因表达谱的变化，为进一步研究RhoA信号转导通路奠定基础。方法：用pSilencer3．1载体构建RhoA／siRNA重组质粒。Effectene转染试剂转染AGS细胞，空载体pSilencer3．1转染对照组。应用G418筛选转染细胞系，获得稳定转染细胞；美国Agilent基因芯片检测细胞基因表达谱变化。结果：基因芯片检测全基因组，发现表达上调的有1151个基因，表达下调的有1079个基因，涉及信号转导、细胞周期、细胞凋亡等相关信号分子。生物信息学分析显示，与细胞凋亡有关的caspase家族，以及细胞周期调控基因存在明显的差异表达。结论：基因芯片结果提示干扰RhoA表达后，与凋亡和增殖有关的分子在RhoA介导的肿瘤细胞异常增殖信号转导中起着重要的调控作用，为下一步研究其信号调控网络机制提供重要的信息。     

层黏连蛋白受体参与缺氧诱导胃癌多药耐药的机制研究

目的：研究缺氧对胃癌细胞对于化疗药物敏感性的影响以及层黏连蛋白受体在缺氧诱导的胃癌MDR中的作用和分子机制。方法：MTT比色法、Annexin V/PI染色法和阿霉素的蓄积和潴留实验检测胃癌细胞在缺氧和常氧状态下对化疗药物敏感性的差异;Western blot和半定量RT-PCR检测缺氧条件下胃癌细胞中67Kda层黏连蛋白受体（67Kda laminin receptor,67LR）的表达;Western blot、半定量RT-PCR方法检测缺氧条件下胃癌细胞系SGC7901中67LR的表达和活性;利用siRNA干涉67LR的表达,MTT比色法、AnnexinV/PI染色法检测缺氧条件下调下胃癌细胞系67LR的表达对化疗药物敏感性的影响。结果：缺氧能够显著降低胃癌细胞对化疗药物的敏感性,以及化疗药物诱导的凋亡和药物在细胞内的潴留和蓄积;缺氧能够显著上调67LR的表达和转录活性;67LR siRNA能够抑制LR的表达;抑制67LR的表达能够显著逆转缺氧诱导的胃癌的MDR表型。结论：缺氧能够增加胃癌细胞对于化疗药物的抵抗,通过上调67LR表达,加剧了缺氧诱导的胃癌多药耐药表型,抑制67LR的表达能够逆转缺氧诱导的胃癌多药耐药的发生。     

EPHA2通过增强Akt/mTOR信号通路促进SGC-7901细胞的增殖

背景与目的：EPHA2能够促进胃癌细胞中Cyclin D1的表达及胃癌细胞的细胞周期进程,从而增强胃癌细胞的增殖能力,但EPHA2调控胃癌细胞中Cyclin D1的表达及胃癌细胞的细胞周期进程的分子机制依然不明确。Akt/mTOR信号通路能够通过促进胃癌细胞中Cyclin D1的表达及胃癌细胞的细胞周期进程增强胃癌细胞的增殖能力,且有研究表明EPHA2能够激活Akt/mTOR信号通路。基于此,该研究探讨了Akt/mTOR信号通路在EPHA2促胃癌细胞增殖中的作用。方法：采用蛋白[质]印迹法(Western blot)检测过表达EPHA2和敲低EPHA2表达对SGC-7901细胞中Akt、mTOR和4EBP1磷酸化的影响。使用Akt抑制剂MK2206和mTOR抑制剂RAD001分别处理转染空载体病毒的SGC-7901-NC细胞和过表达EPHA2的SGC-7901-EPHA2细胞,分别通过CCK8、流式细胞术和Western blot检测细胞增殖、细胞周期及周期相关蛋白Cyclin D1的表达。结果：过表达EPHA2增强SGC-7901细胞中Akt、mTOR和4EBP1的磷酸化,敲低EPHA2的表达抑制SGC-7901细胞中Akt、mTOR和4EBP1的磷酸化。MK2206和RAD001处理细胞时,EPHA2过表达对SGC-7901细胞增殖、细胞S期和Cyclin D1表达的促进作用被显著抑制。结论：EPHA2通过增强Akt/mTOR信号通路促进胃癌细胞SGC-7901的增殖能力,提示我们将来针对EPHA2高表达的胃癌患者或许可以采用Akt抑制剂和mTOR抑制剂予以个体化治疗。     

RhoA、RhoC及其效应分子ROCK-1的表达与卵巢癌细胞系恶性行为相关性的体外研究

目的　研究RhoA、RhoC及其效应分子ROCK 1在卵巢癌细胞中的表达水平 ,探讨其与卵巢癌转移的相关性。方法　逆转录聚合酶链反应 (RT PCR)检测RhoA、RhoC及ROCK 1在SW6 2 6、Skov 3、A2 780和Caov 34种卵巢癌细胞中mRNA的表达水平 ;Westernblot法检测RhoA和ROCK 1蛋白质的表达情况 ;Boyden小室体外侵袭试验测定 4种卵巢癌细胞的体外迁移与侵袭能力。结果　RhoA、RhoC和ROCK 1在 4种卵巢癌细胞中呈不同程度表达 ,其中仅RhoC的表达水平与癌细胞侵袭力和迁移能力呈正相关 (r=0 .95 ,P <0 .0 1)。RhoA在转录水平和蛋白水平中呈不同步变化 ,且RhoA和RhoC的表达与ROCK 1的表达无相关性。 4种卵巢癌细胞的体外侵袭和迁移能力相一致 ,其中SW6 2 6最强 ,Caov 3最弱 ,Skov 3和A2 780居中。结论　RhoC的表达与卵巢癌细胞的体外侵袭和迁移能力相关 ,可能作为一个独立因素在卵巢癌的转移过程中起作用 ,有望成为阻断卵巢癌转移的新靶点。     

TUG1通过调控EZH2促进胃癌细胞侵袭转移的机制研究

目的:探讨牛磺酸上调基因1(TUG1)在胃癌细胞侵袭转移中的作用及其调控机制。方法:TCGA数据库分析TUG1在胃癌组织中的表达且与患者预后的关系;qRT-PCR检测胃癌组织和细胞中TUG1表达;细胞转染构建TUG1过表达后敲减细胞系;Transwell实验观察TUG1过表达和敲减对胃癌SGC-7901细胞迁移和侵袭能力的影响;Western Blot检测TUG1过表达和敲减对胃癌SGC-7901细胞中EZH2/STAT3信号通路活性的影响。结果:TUG1在胃癌组织和细胞中表达上调(P<0.01),与患者的预后呈负相关(P<0.01),而与其病理分期和淋巴转移呈正相关(P<0.05)。Transwell实验结果显示,上调TUG1表达促进胃癌细胞的迁移和侵袭(P<0.01)。Western Blot结果显示,上调TUG1表达可促进EZH2表达,并激活STAT3信号通路(P<0.01)。结论:TUG1通过激活EZH2/STAT3信号通路促进胃癌细胞的侵袭转移。     

A distinct role of RhoB in gastric cancer suppression

Although Rho family GTPases RhoA, RhoB and RhoC share more than 85% amino acid sequence identity, they may play distinct roles in tumor progression. RhoA and RhoC have been suggested to have positive effects on tumor progression, but the role of RhoB in cancer, particularly in gastric cancer, remains unclear. In our study, we have examined the expression levels of these three Rho GTPases in a large panel of specimens from gastric cancer patients by immunohistochemistry. We found that RhoA and RhoC expression were significantly elevated, while RhoB was reduced or absent, in surgically removed gastric cancer tissues when compared to normal gastric tissues. The significant reduction of RhoB expression was confirmed in another group of gastric cancer samples in comparison to the adjacent non‐neoplastic tissues. Then we transfected the plasmids containing RhoA, RhoB or RhoC cDNA into two gastric cancer cell lines, SGC7901 and AGS cells, respectively. By overexpression experiments, we found that RhoA promoted the gastric cancer cell proliferation and RhoC stimulated migration and invasion of the cancer cell. RhoB expression, however, significantly inhibited the proliferation, migration and invasion of the gastric cancer cells and also enhanced the chemosensitivity of these cells to anticancer drugs. It appears that RhoB plays an opposing role from that of RhoA and/or RhoC in gastric cancer cells. Our work suggests that RhoB may play a tumor suppressor role and subsequently may have potential implications in future targeted therapy.     

RhoA and RhoC proteins promote both cell proliferation and cell invasion of human oesophageal squamous cell carcinoma cell lines in vitro and in vivo

There is growing evidence that Rho proteins are deregulated by overexpression in tumours; and according to some reports, this correlates with disease progression. Our previous clinical study had demonstrated a correlation between RhoA expression and tumour progression in oesophageal squamous cell carcinoma (ESCC). These findings prompted us to study, using nude mice, pathological roles of Rho proteins in human ESCC cells. Western blot analysis in ESCC cell lines, in addition to cell proliferation and in vitro migration assays, were performed to observe the malignant potential of RhoA and RhoC in untransfected and transfected cells. Constitutively active RhoA, RhoC and dominant negative RhoA (dnRhoA) proteins were transfected to ESCC (TE-1 and TE-2) cells. The stably transfected cells were injected into nude mice, and the growth and metastasis of these cells to the lungs were analysed. Tumour tissues were then examined using immunohistochemical methods for proteins Ki-67 (MIB-1), FAK, MMP-1, MMP-9 and TIMP-3. Protein levels of RhoA and RhoC in ESCC cell lines were visualised by Western blotting, and showed highest expression in TE-2 cells. Results from the migration assay illustrated that both RhoA and RhoC play a role in migration of ESCC cells. In TE-2 transfected cells, RhoC showed greater migration compared to RhoA. By using an experimental metastasis model in nude mice, RhoA was found to promote more tumour growth than RhoC, whereas RhoC induced lung metastasis in comparison to RhoA. Ki-67 labelling index was used to evaluate the proliferation potential of tumour tissue inoculated from nude mice. In TE-2 cells RhoA gave a proliferation capacity of 24.8+/-0.5, which was significantly higher than those of TE-2 RhoC 10+/-0.4 (P<0.01). Strong immunoreactivity for FAK, MMP-1 and MMP-9 proteins was present in all tumour cells. By contrast, loss of TIMP-3 expression was observed in all tumour cells. In conclusion, our results indicate that pro-oncogenic Rho proteins are involved in promoting tumour growth, cell migration and metastasis in human ESCC cells in nude mice. The results from this study suggest that active Rho proteins may induce a transforming effect that leads to a malignant phenotype.     

Inactivation of Rho GTPases by p190 RhoGAP reduces human pancreatic cancer cell invasion and metastasis

A number of small GTPases are involved in cancer cell proliferation, migration and invasion, acting as molecular switches that cycle between GTP- and GDP-bound states. GTPase-activating proteins (GAPs) have been established as a major class of negative regulators of Rho GTPase signaling. To investigate the biological function of p190 RhoGAP toward RhoA in cancer cell invasion and metastasis, we generated a chimera made of the RhoGAP domain of p190 and the C-terminus of RhoA (p190-RhoA chimera), and transfected it into human pancreatic cancer cells, AsPC-1. Epidermal growth factor (EGF)-induced activation of RhoA, as well as RhoB and RhoC, to a lesser extent, was significantly inhibited in p190-RhoA chimera-transfected AsPC-1 cells compared with that of control cells (mock-infected), when assessed by pull-down assay for GTP-bound RhoA, RhoB, and RhoC, respectively. EGF-induced invasion of p190-RhoA chimera transfectants was significantly inhibited compared with that of mock-infected cells in a modified Boyden chamber assay. Furthermore, the mice injected intrasplenically with AsPC-1 cells that overexpressed the p190-RhoA chimera had a marked reduction in the number and size of metastatic nodules in the liver. These data suggest that the inhibitory action of p190 RhoGAP toward RhoA offers a novel approach to the treatment of invasion and metastasis of cancer cells.     

Clinical significance of Rho GDP dissociation inhibitor 2 in colorectal carcinoma

Background  

Small GTPase proteins, including RhoA, RhoB, RhoC, Rac1, and cdc42, are important molecules for linking cell shape and cell-cycle progression because of their role in both cytoskeletal arrangements and mitogenic signaling. Over-expression of wild-type or constitutively active forms of RhoA has been shown to induce invasive behavior in non-invasive rat hepatoma cells in vitro. In addition, over-expression of RhoC has been found in melanoma cells with increasing metastatic activity as well as inflammatory breast cancer. These results indicate that overexpression of Rho proteins contributes to cancer cell invasion and metastasis. Rho GDP dissociation inhibitor 2 (RhoGDI2) was recently shown to act as a metastasis suppressor gene in bladder cancer. The purpose of this study was to clarify the clinical significance of this gene expression in patients with colorectal carcinoma.     

RhoA在胃癌细胞中的表达及其作用

目的 探讨RhoA在胃癌细胞系中的表达及其作用。方法 Westem blot方法检测RhoA在多株人消化道肿瘤细胞系中的表达;构建RhoA反义核酸真核表达载体,脂质体法转染至高表达RhoA的人胃癌细胞系AGS,MTT比色法观察细胞生长,流式细胞仪检测细胞周期分布。结果 10株肿瘤细胞系中RhoA蛋白表达均显著高于永生化正常人肠黏膜细胞系HIEC。转染RhoA反义核酸真核载体后,AGS细胞中RhoA蛋白表达降低,细胞生长受到抑制,细胞周期分析显示聚集在S期的细胞明显增多。结论 RhoA蛋白在消化道肿瘤细胞系中表达明显增高,降低RhoA表达能部分逆转胃癌细胞的恶性表型。     

Critical functions of RhoB in support of glioblastoma tumorigenesis

Background

RhoB is a member of the Rho small GTPase family that regulates cytoskeletal dynamics and vesicle trafficking. The RhoB homologs, RhoA and RhoC, have been shown to promote cancer progression and metastasis. In contrast, the functions of RhoB in human cancers are context dependent. Although expression of RhoB inversely correlates with disease progression in several epithelial cancers, recent data suggest that RhoB may support malignant phenotypes in certain cancer types.

Methods

We assessed RhoB protein levels in glioma surgical specimens and patient-derived xenografts. The roles of RhoB in glioblastoma were determined by loss-of-function and gain-of-function assays in vitro and in vivo. The impact on p53 and STAT3 signaling was investigated.

Results

RhoB expression was similar in tumor specimens compared with normal neural tissues obtained from epilepsy surgery. RhoB was expressed in the vast majority of xenograft tumors and spheroid cultures. Knockdown of RhoB induced cell-cycle arrest and apoptosis and compromised in vivo tumorigenic potential. However, overexpression of wild-type RhoB or a constitutively active mutant (RhoB-V14) did not significantly affect cell growth, which suggests that RhoB is not a rate-limiting oncogenic factor and is consistent with the scarcity of RhoB mutations in human cancer. Knockdown of RhoB reduced basal STAT3 activity and impaired cytokine-induced STAT3 activation. In glioblastoma tumors retaining wild-type p53, depletion of RhoB also activated p53 and induced expression of p21^CIP1/WAF1.

Conclusions

Our data suggest that RhoB belongs to an emerging class of “nononcogene addiction” factors that are essential for maintenance of malignant phenotypes in human cancers.