CIAPIN1 confers multidrug resistance by upregulating the expression of MDR-1 and MRP-1 in gastric cancer cells

In a previous study, we observed that cytokine-induced apoptosis inhibitor 1 (CIAPIN1), a newly identified apoptosis inhibitor, was upregulated at the mRNA level in a multidrug-resistant gastric cancer cell line SGC7901/VCR. The aim of this study was to explore the role of CIAPIN1 in the development of multidrug resistance (MDR) in gastric cancer cells. Upregulation of CIAPIN1 in MDR gastric cancer cells was confirmed by semiquantitative RT-PCR and Western blotting. Using cDNA transfection and RNA interference, we successfully established stable transfectants with upregulation (i.e., SGC7901-pCIAPIN1) or downregulation (i.e., SGC7901-pSiCIAPIN1 and SGC7901/ADR-pSiCIAPIN1) of CIAPIN1 expression, respectively. In vitro drug sensitivity assay demonstrated that overexpression of CIAPIN1 conferred MDR in SGC7901 cells whereas downregulation of CIAPIN1 sensitized SGC7901 and SGC7901/ADR cells to anticancer drugs. CIAPIN1 protected both SGC7901 and SGC7901/ADR cells from ADR-induced apoptosis and reduced intracellular accumulation and retention of adriamycin. Moreover, expression of P-glycoprotein (P-gp or MDR-1, a product of MDR-1 gene) and MDR-related protein-1 (MRP-1) was upregulated by CIAPIN1. In addition, Western blotting revealed that CIAPIN1 decreased the expression of Bcl-2, Bax and p53. Therefore, it is concluded that CIAPIN1 confers MDR in gastric cancer cells, likely by upregulating MDR-1 and MRP-1.     

锌带基因ZNRD1在胃癌耐药细胞中的表达和功能

目的 探讨锌带基因ZNRD1在多药耐药胃癌细胞中的表达和作用。方法 应用Northern blot和半定量RT—PCR,观察锌带基因ZNRD1在胃癌细胞SGC7901及其长春新碱(VCR)诱导的耐药细胞SGC7901／VCR中的表达;将反义核酸转染SGC7901／VCR细胞,通过免疫组化检测转导细胞与非转导细胞ZNRD1蛋白的表达;以流式细胞仪检测细胞周期的变化,以MTT实验检测细胞生长曲线和对VCR、阿霉素(ADM)的药敏性。结果 胃癌耐药细胞SGC7901／VCR与非耐药细胞相比,ZNBDl基因的表达明显增高。转导株antiZNRDl—SGC7901／VCR细胞的ZNRD1蛋白水平明显低于非转导株,C1期细胞比例增加而S期比例减少,生长受到抑制,且对VCR、ADM的敏感性明显增高。结论 胃癌耐药细胞与非耐药细胞相比,ZNRDl基因处于高表达状态。反义核酸转染可有效阻断ZNRDl蛋白的表达,在一定程度上逆转人胃癌耐药细胞SGC7901／VCR的多药耐药性。     

lncRNA MALAT1/miR-141-3p/ZEB1 分子轴调控胃癌SGC7901 细胞的侵袭、迁移及上皮间质转化

[摘要] 目的：探究lncRNA MALAT1/miR-141-3p/ZEB1 分子轴对胃癌（GC）SGC7901 细胞侵袭、迁移及上皮间质转化（EMT）的调控作用。方法：收集2014 年4 月至2017 年5 月武汉商职医院普外科手术切除的GC组织（非坏死部分）和配对癌旁组织（距肿瘤组织>5 cm）标本38 例,同时选取正常胃上皮细胞GES1 及GC细胞系SGC7901、HGC27、BGC823、MKN45 和MKN28。qPCR实验检测MALAT1、miR-141-3p 在GC组织和细胞系中的表达水平,CCK-8 和Transwell 实验检测敲降MALAT1 对SGC7901 细胞增殖、迁移和侵袭的影响,WB 实验检测ZEB1、E-cadherin、N-cadherin 和Vimentin 的表达情况。双荧光酶素报告基因验证MALAT1、miR-141-3p 和ZEB1 的靶向关系,CCK-8 和Transwell 实验检测MALAT1/miR-141-3p/ZEB1 分子轴对SGC7901 细胞生物学行为的影响。结果：MALAT1 在GC组织和细胞系中高表达（P<0.05 或P<0.01）。敲降MALAT1 显著抑制了SGC7901 细胞增殖、迁移、侵袭及EMT（P<0.05 或P<0.01）;MALAT1 与miR-141-3p、miR-141-3p 与ZEB1 均具有直接靶向关系;进一步研究表明,同时过表达miR-141-3p 和MALAT1 或ZEB1 能够逆转miR-141-3p 对SGC7901 细胞生物学行为的抑制作用。结论：MALAT1通过靶向下调miR-141-3p 对ZEB1 的抑制作用,进而促进SGC7901 细胞侵袭、迁移及EMT。     

MGr1-Ag is associated with multidrug-resistant phenotype of gastric cancer cells

BACKGROUND: MGr1-antigen (Ag) was previously reported as an upregulated protein in multidrug-resistant (MDR) gastric cancer cells. The aim of this study was to characterize the role of MGr1-Ag in the multidrug resistance of gastric cancer cells. METHODS: Laser scanning confocal microscopy (LSCM), two-dimensional electrophoresis, and Western blot were used to detect MGr1-Ag in gastric cancer cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to determine the sensitivity of the MDR gastric cancer cells, SGC7901/VCR, to chemotherapeutic drugs. Adriamycin accumulation and retention in SGC7901/VCR cells were analyzed using flow cytometry. RESULTS: LSCM showed that MGr1-Ag localized mainly on the membrane and partly in the cytoplasm of SGC7901/VCR cells. Western blot showed that the expression level of MGr1-Ag in SGC7901/VCR cells was higher than that in its parental cells, SGC7901, and that the apparent molecular weight and isoelectric point of MGr1-Ag were 42 kDa and pH 4.8, respectively. After incubation with MGr1 antibody, SGC7901/VCR cells showed significantly decreased IC(50) values for adriamycin (from 0.887 +/- 0.081 mg/l to 0.607 +/- 0.084 mg/l; P, 0.05), vincristine (from 0.707 +/- 0.055 mg/l to 0.557 +/- 0.042 mg/l; P, 0.05), and 5-fluorouracil (from 4.367 +/- 0.407 mg/l to 2.630 +/- 0.644 mg/l; P, 0.05), as well as slightly increased IC(50) values for mitomycin (from 0.183 +/- 0.045 mg/l to 0.198 +/- 0.048 mg/l; P. 0.05). In addition, incubation with MGr1 significantly enhanced adriamycin accumulation and retention in SGC7901/VCR cells. CONCLUSION: Overexpression of MGr1-Ag is associated with the MDR phenotype of gastric cancer cells.     

MicroRNA-200c Regulates the Sensitivity of Chemotherapy of Gastric Cancer SGC7901/DDP Cells by Directly Targeting RhoE

Gastric cancer remains a worldwide burden as the second leading cause of cancer-related death. Drug resistance of chemotherapy looms as a major clinical obstacle to successful treatment. Recent evidence indicated that miRNA-200c can restore the sensitivity of NSCLC cells to cisplatin and cetuximab. The expression of miRNA-200c and RhoE were investigated in gastric cancer tissues and cells (SGC7901 and SGC7901/DDP) by qRT-PCR. A luciferase reporter assay was done to understand the potential correlation between miRNA-200c and RhoE. Pre-miR-200c was transfected in SGC7901/DDP cells to confirm whether miRNA-200c could regulate RhoE expression. RhoE was knocked down to explore the role of RhoE on sensitivity of chemotherapy in gastric cancer by MTT. Western blot analysis was performed to further explore the mechanism of RhoE in regulating drug resistance. The results showed that miRNA-200c was significantly lower in cancerous tissues than those in the paired normal tissues, whereas the expression of RhoE was just the opposite. The significant difference of miRNA-200c and RhoE were observed between SGC7901 cells and SGC7901/DDP cells. miRNA-200c has target sites in the 3’-UTR of RhoE mRNA by luciferase reporter assay. Transfection of pre-miR-200c reduces RhoE expression. Meanwhile, the knockdown of RhoE enhanced the sensitivity of SGC7901/DDP cells and changed expression of some genes. These suggested that miRNA-200c regulated the sensitivity of chemotherapy to cisplatin (DDP) in gastric cancer by possibly targeting RhoE.     

Reversal of multidrug resistance of gastric cancer cells by downregulation of TSG101 with TSG101siRNA

We have previously identified tumor susceptibility gene101 (TSG101), overexpressed in vincristine-resistant human gastric adenocarcinoma cell line SGC7901/VCR using a modified subtractive hybridization method and Western blot. In the present study, we constructed two siRNA eukaryotic expression vectors of TSG101 and transfected them into SGC7901/VCR cells to examine whether the down-regulation of TSG101 increased cell sensitivity towards chemotherapeutic drugs. After transfection, the expression of TSG101 was dramatically decreased in TSG101 siRNA transfectants compared with that in parental cells and empty vector control cells. The down-regulation of TSG101 could significantly enhance the sensitivity of SGC7901/VCR cells to vincristine and adriamycin. The capacity of cells to efflux adriamycin markedly decreased in TSG101 siRNA transfectants. These observations suggested that the siRNA constructs of TSG101 we made could effectively down-regulate the expression of TSG101 and reverse the resistant phenotype of gastric cancer cells. The preliminary study suggested that TSG101 might play an important role in multidrug resistance of gastric carcinoma.     

Regulation of multidrug resistance by ribosomal protein l6 in gastric cancer cells

Ribosomal proteins (RP) L6 was previously identified as an up-regulated gene in multidrug-resistant gastric cancer cells SGC7901/ADR comparing to its parental cells SGC7901 by subtractive hybridization. The aim of this study was to explore the roles of RPL6 in multidrug resistance (MDR) in gastric cancer cells. Northern and Western blot analysis confirmed that RPL6 was overexpressed in SGC7901/ADR cells. By gene transfection, RPL6 was genetically upregulated in SGC7901 or down-regulated in SGC7901/ ADR cells. Upregulation of RPL6 was associated with enhanced resistance to multiple anticancer drugs (adriamycin, vincristine, etoposide, 5-fluorouracil and cisplatin) and to adriamycin-induced apoptosis. Downregulation of RPL6 reversed MDR and sensitized cells to adriamycin-induced apoptosis. Alteration of RPL6 showed no obvious influence on intracellular adriamycin accumulation, glutathione content and expression of glutathione S-transferase. RPL6 could upregulate Bcl-2 and downregulate Bax in cells. Together, this work demonstrates that RPL6 could regulate MDR in gastric cancer cells by suppressing drug-induced apoptosis.     

Overexpression of ZNRD1 promotes multidrug-resistant phenotype of gastric cancer cells through upregulation of P-glycoprotein

ZNRD1, a new zinc ribbon gene, has been previously identified as an upregulated gene in a multidrug-resistant gastric cancer cell line SGC7901/VCR comparing to its parental cell SGC7901 by subtractive hybridization and RT-PCR. The antisense nucleic acid for ZNRD1 could enhance adriamycin accumulation in SGC7901/VCR cells and sensitize SGC7901/VCR cells to vincristine. The present study aims to explore the role of ZNRD1 in multidrug resistance in gastric cancer cells. Upregulation of ZNRD1 protein in SGC7901/VCR cells was confirmed by Western blot and immunocytochmical staining. ZNRD1 was genetically overexpressed in SGC7901 cells by gene transfection. It was found that overexpression of ZNRD1 could sensitize SGC7901 cells to P-glycoprotein (P-gp)-related anticancer drugs (vincristine, adriamycin, etoposide) but not to P-gp-nonrelated drugs (5-fluorouracil and cisplatin), which was accompanied with significantly decreased adriamycin accumulation and retention and increased adriamycin releasing in SGC7901 cells. Verapamil, an inhibitor for P-gp, could reverse the effects of ZNRD1 on drug sensitivity and drug accumulation in SGC7901 cells to a great extent. Western blot and Northern blot revealed that overexpression of ZNRD1 could upregulate P-gp at both protein and mRNA levels. Together, these results suggest that overexpression of ZNRD1 could promote multidrug-resistant phenotype of gastric cancer cells through upregulation of P-gp.     

Shugoshin1 enhances multidrug resistance of gastric cancer cells by regulating MRP1, Bcl-2, and Bax genes

Multidrug resistance (MDR) is a major clinical obstacle in treatment of gastric cancer (GC) and it accounts for the majority of cancer-related mortalities. Shugoshin1 (SGO1) is an important player in appropriate chromosome segregation and is involved in tumorigenesis. In this study, we found endogenous SGO1 overexpression in the multidrug-resistant GC cell lines SGC7901/VCR and SGC7901/ADR compared with their parental cell line SGC7901. By enhancing expression of SGO1, sensitivity of SGC7901 cells to vincristine (VCR), adriamycin, 5-fluorouracil (5-FU), and cisplatin (CDDP) was significantly diminished. Silencing its expression resulted in enhanced sensitivity of SGC7901/VCR and SGC7901/ADR cells to these antitumor drugs. Additionally, we confirmed that SGO1 increased capacity of cells to enable adriamycin (ADR) efflux and inhibit drug-induced apoptosis by regulating MRP 1, Bcl-2, and Bax genes so as to confer a MDR phenotype to GC cells. In brief, these findings suggest that SGO1 promotes MDR of GC cells and may be useful as a novel therapeutic target for preventing or reversing MDR.     

甲基莲心碱对耐长春新碱人胃癌细胞多药耐药性逆转机制的初步研究

目的探讨新的钙阻断剂甲基莲心碱(Nef)对耐长春新碱人胃癌细胞多药耐药性(MDR)的逆转作用及其机制。方法采用MTT比色法,检测药物的细胞毒作用;应用免疫细胞化学SP法及流式细胞术,检测Nef对人胃癌细胞Bcl-2蛋白表达的影响。结果 10μmol/L Nef对SGC7901及SGC7901/VCR无显著细胞毒作用;2.5、5、10μmol/L Nef能使VCR对SGC7901/VCR细胞的IC50从2.32μg/ml依次下降至0.340、0.128、0.053μg/ml,逆转倍数分别为6.8、18.1、43.8。当Nef浓度为10μmol/L时,逆转SGC7901/VCR多药耐药活性较VRP高(P<0.01);SGC7901/VCR细胞中Bcl-2蛋白表达水平较SGC7901细胞高,经Nef处理后,SGC7901/VCR细胞中Bcl-2蛋白表达水平明显下降,表明Nef能下调SGC7901/VCR细胞中Bcl-2蛋白表达水平。结论甲基莲心碱在体外能逆转耐长春新碱人胃癌细胞(SGC7901/VCR)的多药耐药性,其机制可能与下调Bcl-2蛋白表达水平有关。     

人核糖体蛋白S13(RPS13)编码基因的克隆及其正反义核酸转染胃癌细胞的初步研究

目的：扩增人核糖体蛋白S13（RPS13）编码基因序列，构建其正，反义真核表达载体，分别转染胃癌细胞SGC7901及胃癌耐药细胞SGC7901/VCR，以进一步研究RPS13基因与胃癌多药耐药的关系。方法：采用RT-PCR法扩增RPS13cDNA片段编码区全长序列，利用DNA重组技术的建正，反义真核表达载体，经脂质体介导转染胃癌细胞SGC7901及胃癌耐药细胞SGC7901/VCR，筛选正，反义基因稳定转染细胞，RNA斑点杂交法检测正，反义稳定转染细胞mRNA水平的变化。结果：从高表达RPS13的SGC7901/VCR耐药细胞中提取细胞总RNA，RT-PCR法成功扩增了RPS13cDNA片段编码区全长序列，并经测序证实；目的基因因按正，反两个方向亚克隆至真核表达载体pcDNA3.1( ),并经酶切鉴定证实；经脂质体介导将正义真核表达载体转染SGC7901细胞，反义真核表达载体转染SGC7901/VCR细胞，G418筛选获得稳定转染细胞；RNA斑点杂交试验证实；正义稳定转染细胞RPS13mRNA水平上调，反义稳定转染细胞RPS13mRNA水平下调。结论：成功克隆了人RPS13编码基因序列，并构建了其正，反义真核表达载体，在胃癌细胞系SGC7901及长春新碱耐药细胞SGC7901/VCR中得到稳定转染细胞，正义转染细胞中RPS13mRNA表达明显增加，反义转染细胞中表达明显受抑。     

反义核酸抑制胃癌细胞Bcl-2表达

本文采用分子克隆技术成功地构建了反义核酸表达载体pDOR-Bcl-2 cDNA.以脂质体介导法将重组反义核酸表达载体转染受体细胞SGC7901,并经C418筛选,从2×10~5细胞中筛选出大约150个抗性克隆,转导率大于1‰,随机挑选2个克隆继续筛选与扩增培养,获得了1株稳定的抗性细胞,从而建立了Bcl-2表达阻断的胃癌细胞株,我们命名为7901anBcl-2 cells.通过Southern印迹法、Northern印迹法、Western印迹法检测显示,转导株与非转导株均有Bcl-2 cDNA的表达,但转导株Bcl-2 mRNA及蛋白的表达明显低于非转导株.说明在胃癌细胞中Bcl-2基因处于高表达状态,通过真核表达载体介导的转染,反义Bcl-2可成功地导入胃癌细胞,并有效地阻断Bcl-2表达.     

A Sphingosine Kinase-1 Inhibitor,SKI-II,Induces Growth Inhibition and Apoptosis in Human Gastric Cancer Cells

SKI-II has been reported as an inhibitor of sphingosine kinase 1 and has been extensively used to prove theinvolvement of sphingosine kinase and sphingosine-1-phosphate (Sphk1) in cellular processes. In the currentstudy, we investigated the effects of SKI-II and its potential mechanisms in human gastric cancer SGC7901cells. After treatment with SKI-II, cell growth, cell cycle distribution, apoptosis, expression of Sphk1, NF-κB,Bcl-2, Bax and p27 were assessed by MTT assay, flow cytometry, electron microscopy, immunocytochemistryand Western-blot assay, respectively. Our results showed that SKI-II markedly inhibited SGC7901 cell survivalin a dose-dependent manner, reduced cell proliferation with accumulation of cells in the G0/G1 phase andinduced apoptosis in the tumor cells. Furthermore, Western blotting and immunocytochemistry showed that theexpression of p27 and Bax was increased significantly, but the expression of NF-κB, Bcl-2 and Sphk1 decreasedby different degrees. These results indicate that SKI-II induced cell growth arrest and apoptosis. The increasedapoptotic sensitivity of SGC7901 was correlated with NF-κB or Bcl-2/Bax activation.     

Af116609基因对胃癌细胞系SGC7901/VCR耐药性的影响

目的 研究Af116609基因转染胃癌耐药细胞系SGC7901／VCR后,对胃癌细胞耐药性的影响。方法 采用RT-PCR法克隆Af116609基因,用Northern blot检测其差异表达,以基因转染技术调节其表达,通过体外药敏实验观察其对胃癌耐药表型的影响。结果 从胃癌耐药细胞SGC7901／VCR中克隆到Af116609基因的CDS序列327bp,该序列与GenBank登录的一致。Northern blot结果显示,该基因在耐药细胞高表达。体外药敏实验发现,转染正义真核表达载体的药敏细胞中该基因上调,对长春新碱、5-氟脲嘧啶和阿糖胞苷的耐药性增加,而对阿霉素的抗性有损害,对氨甲喋呤的抗性无明显影响;转染反义真核表达载体的耐药细胞中该基因下调,对上述5种药物的抗性均减弱。结论 Af116609基因与胃癌MDR表型相关,可作为逆转胃癌MDR的候选靶分子。     

慢病毒介导5HRE-CEAp调控RASSF1A表达对胃癌细胞SGC7901抑制的研究

目的:探讨5拷贝低氧反应元件（5HRE）联合癌胚抗原启动子(CEAp)调控抑癌基因RAS相关域家族1A(RASSF1A)的慢病毒载体(LV-5HRE-CEAp-RASSF1A)对胃癌细胞SGC7901的体外抑制作用。方法:采用qRT-PCR方法检测空白对照组细胞SGC7901、阴性对照组细胞SGC7901/NC及慢病毒载体感染的实验组细胞SGC7901/5HRE-CEAp-RASSF1A中RASSF1A mRNA 表达水平;通过CCK-8实验检测各组细胞的生长曲线;通过流式细胞技术检测各细胞的凋亡及细胞周期。结果:qRT-PCR结果显示,与其他组比较,实验组细胞的RASSF1A mRNA水平在低氧条件下明显升高（P<0.01）;CCK-8实验结果显示从第3天开始,低氧条件下实验组细胞的OD值开始低于其它各组细胞（P<0.05）;流式细胞检测结果显示与其它各组细胞比较,低氧条件下实验组细胞凋亡比例明显增加（P<0.01）,并且其细胞周期G1期的细胞百分比明显增加（P<0.05）。结论:慢病毒载体LV-5HRE-CEAp-RASSF1A具有在低氧诱导下显著抑制胃癌细胞株SGC7901增殖的作用。