miR-215对胃癌细胞侵袭转移能力的影响及机制

目的探讨miR-215对胃癌细胞侵袭转移能力的影响及作用机制。方法通过RT-PCR检测miR-215在高转移胃癌细胞株NCIN87,BGC-823,RF-48及低转移细胞株HGC-27及MKN-28中的表达;Transwell迁移及侵袭实验检测miR-215抑制剂对胃癌细胞迁移及侵袭能力的影响;Western印迹检测miR-215抑制剂对胃癌细胞活化白细胞黏附分子(ALCAM),基质金属蛋白酶(MMP)-2,MMP-9,上皮细胞-间充质转化(EMT)相关蛋白E-钙黏附素(E-cadherin),波形蛋白(Vimentin)表达量的影响。结果 RT-PCR结果证实miR-215在高转移胃癌细胞株中的表达高于低转移胃癌细胞中的表达,且miR-215在BGC-823细胞中的表达最高,因此选用BGC-823作为后续实验细胞株。miR-215抑制剂转染BGC-823细胞48 h后,发现下调miR-215表达能显著抑制BGC-823细胞迁移及侵袭能力,并能下调ALCAM,MMP-2,MMP-9及Vimentin表达,上调E-cadherin表达。结论miR-215低表达能显著抑制胃癌细胞BGC-823侵袭及转移能力,与下调MMPs及抑制EMT生成有关。     

β-arrestin1在胃癌细胞BGC-823中的生物学功能

目的 探讨β-arrestin1对胃癌细胞BGC-823增殖、迁移、侵袭及凋亡能力的影响.方法 用实时定量PCR技术及Western印迹法检测人胃黏膜上皮细胞GES和人胃癌细胞株BGC-823、MKN-28、SGC-7901中β-arrestin1的表达水平.应用RNA干扰技术构建稳定干扰β-arrestin1和阴性对照组(pU6空载体)的BGC-823细胞株.进一步应用细胞计数法、划痕实验、Transwell小室实验及流式细胞术分析干扰β-arrestin1和阴性对照组的BGC-823细胞株的增殖、迁移、侵袭能力及凋亡水平的变化.统计学处理采用t检验.结果 β-arrestin1在GES表达量为0.001±0.001,MKN-28表达量为0.002±0.000,SGC-7901表达量为0.003±0.002,BGC-823中表达量为0.005±0.000.干扰β-arrestin1和阴性对照的BGC-823细胞增殖抑制率分别为-30.2％和100.0％.迁移能力受到抑制,穿过基质膜细胞数分别为126.25±3.24和213.50±6.27(t=0.000,P＜0.01),凋亡率为(41.350±1.053)％和(11.497±0.589)％(t=0.015,P＜0.05).结论 β-arrestin1在胃癌细胞中高水平表达,并且随着胃癌细胞恶性度增高而表达量增加,在BGC-823细胞中干扰β-arrestin1后能抑制细胞的生长、迁移、侵袭,并提高凋亡水平.     

MiR-9对人胃癌细胞增殖和迁移的影响

背景:MicroRNA-9(miR-9)参与调控生长、发育、细胞自我更新和多向分化等多种生理过程,而且其表达异常与多种恶性肿瘤密切相关。目的:探讨miR-9对人胃癌细胞生物学行为的影响。方法:以real-time PCR检测人正常胃黏膜上皮细胞株GES-1和人胃癌细胞株BGC-823、SGC-7901中的miR-9表达。采用瞬时转染法将miR-9类似物、miR-9抑制物和空载体分别转染BGC-823、SGC-7901细胞,并以real-time PCR验证转染效率。CCK-8实验检测细胞增殖能力,Transwell细胞迁移实验和划痕实验检测细胞迁移能力。结果:与正常胃黏膜上皮细胞相比,胃癌细胞miR-9表达显著升高(P0.05)。与空载体对照组相比,miR-9类似物组BGC-823、SGC-7901细胞miR-9表达上调,细胞增殖和迁移能力明显增强(P0.05),miR-9抑制物则可显著抑制胃癌细胞的增殖和迁移能力(P0.05)。结论:上调miR-9表达可促进胃癌细胞增殖和迁移,提示miR-9过表达可能与胃癌进展有关。     

miR-135b-5p靶向KLF4基因调控胃癌SGC-7901细胞生物学行为的研究

目的 研究miR-135b-5p通过靶向KLF4基因对人胃癌SGC-7901细胞生物学行为的影响。方法 通过RT-PCR检测人正常胃黏膜上皮细胞株GES-1及胃癌细胞株SGC-7901、MKN-45、BGC-823、AGS中miR-135b-5p表达水平,将miR-135b-5p inhibitor转染至胃癌SGC-7901细胞中,RT-PCR和Western blotting分别检测转染后细胞中miR-135b-5p和KLF4蛋白表达水平,MTT法、流式细胞术、Transwell实验分别检测转染对细胞增殖、凋亡、侵袭和迁移能力的影响。生物信息学软件预测及双荧光素酶报告基因实验验证KLF4是否为miR-135b-5p的靶基因。结果 胃癌细胞SGC-7901、MKN-45、BGC-823、AGS中miR-135b-5p表达水平显著高于人正常胃黏膜上皮细胞GES-1,且胃癌SGC-7901细胞中miR-135b-5p表达水平最高。在SGC-7901细胞中转染miR-135b-5p inhibitor 48 h后,miR-135b-5p的表达水平显著降低,KLF4 mRNA和蛋白表达水平明显升高。下调miR-135b-5p后SGC-7901细胞增殖能力下降,凋亡率升高,侵袭和迁移能力减弱。双荧光素酶报告基因实验结果显示,KLF4是miR-135b-5p靶基因。结论 miR-135b-5p能够通过靶向KLF4抑制胃癌SGC-7901细胞增殖、侵袭和迁移,诱导细胞凋亡。     

侧群细胞在胃癌细胞株中的分布及其致瘤特性

目的 研究侧群细胞的致瘤特性及其在胃癌细胞株和胃癌组织中的分布.方法 用荧光激活细胞分选法分析SGC-7901、MKN28和BGC-823三种胃癌细胞株中的侧群细胞.取36只裸鼠,分为6组,将SOC-7901分离出的侧群细胞和非侧群细胞分别以每只500、5000、50 000的数量接种到裸鼠皮下,8周后观察成瘤情况.实时定量PCR检测胃癌组织和胃癌细胞株中三磷酸腺苷结合转运蛋白超家族成员G2(ABCG2)mRNA的表达,免疫组化法检测胃癌组织中ABCG2蛋白的表达.结果 SGC-7901细胞株中侧群细胞比例为1.0%,BGC-823为1.3%,MKN28则为阴性.从SGC-7901中分离的侧群细胞最少可成瘤细胞数是500/只,非侧群细胞为50000/只.胃癌细胞株SGC-7901和BGC-823的ABCG2 mRNA相对量高于MKN28(分别为0.162、0.096和0.005).ABCG2 mRNA和蛋白在胃癌和胃炎组织中有不同程度的表达.结论 胃癌细胞株侧群细胞的致瘤能力明显强于非侧群细胞.在胃癌组织和部分胃炎组织中检测到ABCG2的表达,在胃癌细胞株中侧群细胞比例高的细胞株ABCG2表达高.     

内质网应激对胃癌细胞迁移与侵袭的影响

目的:探讨内质网应激(endoplasmic reticulum stress,ERS)对胃癌细胞迁移及侵袭能力的影响及其机制.方法:5μg/mL衣霉素处理胃癌细胞系SGC7901或BGC823 0、12、24及36 h,Western blot检测各时间点葡萄糖调节蛋白78(glucoseregulated protein 78,GRP78)、金属基质蛋白酶9(matrix metalloproteinase 9,MMP9)及血管内皮细胞生长因子(vascular endothelial growth factor,VEGF)的表达;划痕实验检测衣霉素处理不同时间后对胃癌细胞迁移能力的影响,各时间点均设未加药对照组;Transwell侵袭实验检测衣霉素处理不同时间后对胃癌细胞侵袭能力的影响,各时间点均设未加药对照组.结果:与相应的0 h组相比,衣霉素处理胃癌细胞系SGC7901或BGC823 12、24及36 h后,GRP78、MMP9及VEGF的蛋白表达量均明显增加(P0.05);衣霉素处理12、24及36 h后,胃癌细胞的划痕愈合度及胃癌细胞侵袭到Transwell下室的细胞数均明显高于0 h组(P0.05).结论:ERS可上调MMP9及VEGF,促进胃癌细胞的迁移与侵袭.     

PTEN基因表达与胃癌细胞侵袭力的相关性研究

目的探讨PTEN基因mRNA表达与胃癌细胞体外侵袭力的关系。方法采用Boyden小室法测定四种胃癌细胞(SGC-7901、BGC-823、M GC-803、HGC-27)的体外侵袭力、运动力,RT-PCR法检测四种胃癌细胞的PTEN基因mRNA表达水平。结果胃癌细胞体外侵袭力为HGC-27(48±2)、M GC-803(28±2)、BGC-823(30±3)、SGC-7901(13±2);PTEN基因mRNA表达水平为SGC-7901(0.336±0.079)、BGC-823(0.232±0.063)、M GC-803(0.228±0.056)、HGC-27(0.113±0.047);两两比较,P<0.01,>0.05,<0.05。相关分析显示,胃癌细胞体外侵袭力随PTEN基因mRNA表达增高而降低,PTEN基因mRNA表达及胃癌细胞体外侵袭力与细胞分化程度相关。结论PTEN基因参与胃癌的发展过程,并与胃癌的部分生物学行为有关,PTEN基因mRNA表达水平对评价胃癌细胞体外运动侵袭力具有重要价值。     

SiRNA干扰LOX基因对胃癌BGC-823细胞增殖、迁移和侵袭的影响

目的探讨siRNA靶向干扰赖氨酰氧化酶(LOX)基因对胃癌BGC-823细胞增殖、迁移及侵袭能力的影响。方法采用脂质体转染法建立LOX-siRNA的BGC-823细胞株和阴性对照BGC-823细胞株。应用RT-PCR法检测胃癌细胞转染前后LOX mRNA水平,应用Western blotting法检测胃癌细胞转染前后的LOX蛋白表达水平。MTS法检测BGC-823细胞的增殖情况;Transwell迁移和侵袭实验检测干扰LOX基因对BGC-823细胞迁移及侵袭能力的影响。结果与NC-siRNA组及空白组比较,LOX-siRNA转染组LOX mRNA和蛋白表达明显下降(P0.05),细胞增殖、迁移、侵袭能力明显下降(P0.05)。结论 LOX基因对胃癌BGC-823细胞增殖、侵袭及迁移有一定的促进作用。     

ABCG2、MDR1基因表达水平与5-氟尿嘧啶耐药的CD44+SGC-7901/5-Fu多药耐药关系

目的探讨乳腺癌耐药蛋白(ABCG2)、P-糖蛋白(MDR1)基因表达水平与5-氟尿嘧啶(5-Fu)耐药的CD44+SGC-7901/5-Fu多药耐药关系。方法采用反复短期暴露并逐步递增药物浓度法建立5-Fu耐药胃癌细胞株SGC7901/5-Fu,鼠抗人CD44抗体,流式细胞术(FACS)检测分选CD44+SGC-7901/5-Fu。四甲基偶氮唑蓝(MTT)比色法测定SGC-7901/5-Fu、CD44+SGC-7901/5-Fu、CD44-SGC-7901/5-Fu细胞5-Fu耐药指数及交叉耐药性。RT-PCR方法分别检测对数期生长的SGC-7901、SGC-7901/5-Fu、CD44+SGC-7901/5-Fu、CD44-SGC-7901/5-Fu细胞ABCG2、MDR1 mRNA表达。结果 CD44+SGC-7901/5-Fu相对于SGC-7901细胞的耐药指数为12.5(P<0.05),但CD44-SGC-7901/5-Fu相对于SGC-7901细胞的耐药指数为1.2(P>0.05)。CD44+SGC-7901/5-Fu对ADM、MMC和DDP也有交叉耐药性,CD44-SGC-7901/5-Fu对ADM、MMC和DDP无交叉耐药性。与对照组(正常SGC-790)细胞比较,ABCG2、MDR1在5-Fu耐药的SGC-7901细胞株中表达明显增强(P<0.05)。与5-Fu耐药的SGC-7901细胞株比较,CD44+SGC-7901/5-Fu细胞株ABCG2、MDR1表达继续增加(P<0.05);。与5-Fu耐药的SGC-7901细胞株比较,CD44-SGC-7901/5-Fu细胞ABCG2、MDR1表达差别无统计学意义(P>0.05)。结论 CD44+SGC-7901/5-Fu细胞株对5-Fu耐药性明显增强,其多药耐药机制可能与ABCG2、MDR1mRNA表达增加相关。     

长链非编码RNA核仁小分子RNA宿主基因1对胃癌细胞增殖和侵袭的影响

目的探讨长链非编码(lnc)RNA核仁小分子RNA宿主基因(SNHG)1在胃癌中的表达水平及其对胃癌细胞增殖和侵袭过程的影响。方法实时荧光定量-聚合酶链反应(qRT-PCR)检测SNHG1在胃癌细胞SGC7901、BGC823和正常胃上皮细胞NGEC中的表达水平及采用SUHG1的小干扰RNA(si-SNHG1)干扰后SNHG1的表达水平;噻唑蓝(MTT)法检测沉默SNHG1对SGC7901、BGC823细胞增殖的影响,Transwell小室检测沉默SNHG1对SGC7901、BGC823细胞侵袭能力的影响。Western印迹法检测沉默SNHG1前后增殖标志物Ki67和侵袭相关蛋白基质金属蛋白酶(MMP)-2、MMP-9在SGC7901、BGC823中的表达变化。结果 SNHG1在胃癌细胞株中的表达显著高于正常胃上皮细胞株(P0.05);沉默SNHG1能显著抑制Ki67、MMP-2、MMP-9的表达。结论 lncRNA SNHG1在胃癌细胞中高表达,沉默SNHG1对胃癌细胞的增殖、侵袭起抑制作用,SNHG1可能成为治疗胃癌的一个有效靶点。     

Gastric cancer cell lines induced by trichostatin A

AIM： To explore the effect of trichostatin A （TSA） on apoptosis and acetylated histone H3 levels in gastric cancer cell lines BGC-823 and SGC-7901. METHODS： The effect of TSA on growth inhibition and apoptosis was examined by MTT, fluorescence microscopy and PI single-labeled flow cytometry. The acetylated histone H3 level was detected by Western blot. RESULTS： TSA induced apoptosis in gastric cancer cell lines BGC-823 and SGC-7901 was in a dose and time-dependent manner. Apoptotic cells varied significantly between TSA treated groups （37.5 ng/mL 72 h for BGC-823 cell line and 75 ng/mL 72 h for SGC-7901 cell line） and control group （0.85 ± 0.14 vs 1.14 ± 0.07, P = 0.02; 0.94 ± 0.07 vs 1.15 ± 0.06, P = 0.02）. Morphologic changes of apoptosis, including nuclear chromatin condensation and fluorescence strength, were observed under fluorescence microscopy. TSA treatment in BGC-823 and SGC-7901 cell lines obviously induced cell apoptosis, which was demonstrated by the increased percentage of sub-G1 phase cells, the reduction of Gl-phase cells and the increase of apoptosis rates in flow cytometric analysis. The result of Western blot showed that the expression of acetylated histone H3 increased in BGC-823 and SGC-7901 TSA treatment groups as compared with the control group.CONCLUSION： TSA can induce cell apoptosis in BGC-823 and SGC-7901 cell lines. The expression of acetylated histone H3 might be correlated with apoptosis.     

槲皮素对胃癌细胞SGC-7901和BGG-823生长的影响

目的 观察槲皮素对胃癌细胞SGC-7901和BGC-823生长和增殖的影响。方法 以台盼蓝拒染法计数胃癌细胞的生长抑制率，荧光显微镜了解凋亡的发生，流式细胞术检测细胞周期变化。结果 台盼蓝拒染法计数显示槲皮素抑制SGC-7901和BGC-823细胞增殖的作用明显，呈浓度和时问依赖性，槲皮素处理48h后的Ic50为14．12μm(SGC-7901)和28．13μm(BGC-823)。形态学检测显示出细胞凋亡的特征变化，流式细胞仪检测表明经10～20μm／L的槲皮素处理，SGC-7901细胞周期阻滞于G0／G1期，BGC-823细胞周期阻滞于S期。结论 槲皮素能抑制胃癌细胞的生长并诱导其发生凋亡，是有效的抗癌药。     

Characterization of gastric cancer models from different cell lines orthotopically constructed using improved implantation techniques

AIM: To develop orthotopic gastric cancer mouse models from different cell lines and characterize the tumor features to assist further in preclinical trials and clinical treatment strategies.METHODS: Human gastric cancer SGC-7901 and BGC-823 cell suspensions were injected subcutaneously into nude mice to develop solid tumors, and tumor tissue pieces were then implanted under the serous coat of the stomach. An autopsy was performed on all animals of the SGC-7901 and BGC-823 models to observe the primary tumor growth and metastases using pathological and immunohistochemical methods.RESULTS: Both models showed large tumors in situ resulting in pressure and infiltration of the adjacent organs. The gastric cavity became smaller, along with stenosis of the cardia or pylorus. There were biological and statistical differences between the two models. The metastasis rate in involved organs (lymph nodes, kidney, spleen, testis) was significantly higher in the BGC-823 model compared to the SGC-7901 model (P < 0.05 or P < 0.01). The median survival of the BGC-823 model was shorter than that of SGC-7901 (23 d vs 84 d, P < 0.05). Histopathologically, the primary tumor and metastatic lesions of the two models showed obvious atypia and mucus in the cytoplasm. Compared with the SGC-7901 model, BGC-823 appeared more poorly differentiated (absence of adenoid structure), had a smaller volume, and richer capillary structure. Immunohistochemical staining revealed cytokeratin 20 and epithelial membrane antigen expression was positive in the SGC-7901 tumors, while negative in BGC-823 ones.CONCLUSION: Models using the SGC-7901 and BGC-823 cell lines were established which could function in gastric cancer research on carcinogenesis mechanism and drug discovery. The two models showed different tumor behavior and the latter was more malignant than the former.     

hnRNPA1在人胃癌细胞株BGC-823中的生物学功能

核不均一核糖核蛋白A1（hnRNPAl）是体内重要的RNA结合蛋白,通过调节pre-mRNA和mRNA参与转录和转录后调控过程,与肿瘤发生、发展密切相关。目前对hnRNPAl与胃癌的关系尚不十分清楚。目的：探讨hnRNPAl在人胃癌细胞中的生物学功能,明确其与胃癌的关系。方法：以蛋白质印迹法检测正常人胃黏膜上皮细胞株GES一1和人胃癌细胞株MKN-28、SGC-7901、BGC-823中的hnRNPAl表达。构建靶向hnRNPAl基因的siRNA重组质粒并稳定转染BGC一823细胞,以稳转空质粒pU6的细胞株作为对照,蛋白质印迹法验证干扰效果。分别以CCK一8实验、细胞划痕实验、Transwell侵袭实验和流式细胞术分析各组BGC-823细胞的增殖、迁移、侵袭能力和细胞凋亡情况。结果：hnRNPA1在3株人胃癌细胞株中均呈高表达,BGC-823细胞表达水平最高。与pU6稳转组相比,siRNAhnRNPAl稳转组BGC．823细胞增殖抑制率为36．3％,细胞迁移[（5．44±0．25）斗In／h对（9．37±0．49）μm／h,P〈0．01]和侵袭（穿膜细胞数146．30±12．56对312．51±9．62,P〈0．01）受抑,细胞凋亡率降低（3．6％±0．3％对12．7％±0．2％,P〈0．01）。结论：hnRNPAl在人胃癌细胞中呈高表达,其可能通过促进肿瘤细胞增殖、迁移、侵袭,在胃癌侵袭和转移过程中发挥作用。     

Xiaotan Sanjie decoction inhibits interleukin-8-induced metastatic potency in gastric cancer

AIM:To investigate the interaction between Xiaotan Sanjie(XTSJ) decoction and interleukin-8(IL-8) and its effect on adhesion,migration and invasion of SGC-7901 gastric cancer cells.METHODS:SGC-7901 gastric cancer cells were exposed to serum containing XTSJ decoction and/orIL-8(1 ng/m L).SGC-7901 cell adhesion to fibronectin,an extracellular matrix component,was detected using the Cell Counting Kit-8.Migration and invasion abilities of SGC-7901 cells were detected by scratch wound and Transwell chamber assays.Then,protein(immunofluorescence and Western blot) and m RNA levels(quantitative polymerase chain reaction) of cluster of differentiation 44(CD44),a cell adhesion molecule,were measured in 72-h-cultured SGC-7901 cells.RESULTS:Cell adhesion was promoted by IL-8(P = 0.001),but was inhibited by XTSJ decoction(P = 0.0001).Similarly,IL-8 promoted SGC-7901 cell invasion(P = 0.003),and XTSJ decoction inhibited cell invasion(P = 0.001).IL-8 induced SGC-7901 cell migration,but this was inhibited by XTSJ decoction.IL-8 up-regulated CD44 protein(P = 0.028) and m RNA expression(P = 0.002),whereas XTSJ decoction inhibited CD44 protein expression(P = 0.0001),but not m RNA expression(P = 0.275).An interaction between XTSJ decoction and IL-8 was confirmed in the invasion(P = 0.001) and CD44 m RNA expression of SGC-7901 cells(P = 0.010),but not in cell adhesion(P = 0.051).CONCLUSION:XTSJ decoction may inhibit adhesion,migration and invasion of gastric cancer cells,which is partly associated with down-regulation of IL-8.     

Cullin1蛋白在胃癌中的表达及临床意义

目的:研究Cullin1在胃癌细胞及胃癌组织中的表达,并分析Cullin1、临床分期与患者生存率之间的相关性.方法:采用Western blot法检测SGC-7901、BGC-823胃癌细胞与正常胃黏膜上皮细胞GES-1中、胃癌组织与癌旁组织中Cullin1蛋白表达差异.我们利用已经构建的胃癌数据库,采用免疫组织化学法检测792例胃癌组织中Cullin1表达.结果:我们研究发现,SGC-7901、BGC-823胃癌细胞中Cullin1表达水平均高于胃上皮细胞株GES-1(P<0.01).胃癌组织中Cullin1蛋白表达水平均高于癌旁组织(P<0.01).Cullin1过表达与胃癌TNM分期(P=0.011)、浸润深度(P=0.035,T1-T3与T4)及淋巴结转移(P=0.036)显著相关.此外,我们发现Cullin1的高表达与胃癌患者较差的总生存时间及3年生存率明显相关(P=0.042,0.026).Cox回归分析显示,Cullin1表达是胃癌患者3年生存率的一个独立的预后因子(P=0.028).结论:我们的数据表明,Cullin1可作为胃癌淋巴结转移、预后以及潜在治疗的一个重要标志和研究目标.     

Hypermethylation and aberrant expression of Wnt antagonist secreted frizzled-related protein 1 in gastric cancer

AIM： To identify the methylation of secreted frizzled-related protein 1 （SFRP1） in gastric cancer and to investigate the aberrant expression of SFRP1 and its correlation with the clinical pathological features of patients.
METHODS： We determined SFRP1 methylation and SFRP1 mRNA expression in 3 gastric cancer cell lines SGC-7901, BGC-823, HGC-27, from 52 primary gastric cancer specimens and matched tumor adjacent tissue specimens by methylation-specific （MSP） PCR and RT-PCR respectively. Fisher＇s exact test was used to analyze the statistical association between clinical pathological data and aberrant expression of SFRP1.
RESULTS： In 3 cancer cell lines, BGC-823 and HGC-27 had methylated SFRP1 and lost SFRP1 mRNA expression. After treatment of BGC-823 and HGC-27 with the demethylating agent, 5-aza-2′-deoxycytidine, SFRP1 was re-expressed. In 52 primary gastric cancer specimens and matched tumor adjacent tissue specimens, hypermethylation of SFRP1 was detected in 23 （44%） and 8 （15%） specimens respectively （x^2= 10.34, P 〈 0.01）. Loss of SFRP1 expression was detected in 17（33%） and 6 （12%） specimens respectively （x^2= 6.75, P 〈 0.01）. There was a significant correlation between SFRP1 hypermethylation and SFRP1 expression loss. SFRP1 expression was also correlated significantly with tumor stage and lymph node status, but not with patient sex, age and histological type.
CONCLUSION： SFRP1 inactivation is a common and early event caused mainly by hypermethylation in gastric cancer. SFRP1 expression loss may be correlated with tumor metastasis in primary gastric cancer.     

RNAi knockdown of PIK3CA preferentially inhibits invasion of mutant PIK3CA cells

AIM: To explore the effects of siRNA silencing of PIK3CA on proliferation, migration and invasion of gastric cancer cells and to investigate the underlying mechanisms. METHODS: The mutation of PIK3CA in exons 9 and 20 of gastric cancer cell lines HGC-27, SGC-7901, BGC-823, MGC-803 and MKN-45 was screened by polymerase chain reaction (PCR) followed by sequencing. BGC-823 cells harboring no mutations in either of the exons, and HGC-27 cells containing PIK3CA mutations were employed in the current study. siRNA...