Knockdown of lncRNAXLOC＿001659 inhibits proliferation and invasion of esophageal squamous cell carcinoma cells

BACKGROUND Studies have shown that long non-coding RNAs(lnc RNAs) play a key role in almost all key physiological and pathological processes, including different types of malignant tumors. Our previous lnc RNA microarray results have shown that lnc RNA XLOC_001659 is upregulated in esophageal cancer(EC) tissues, with a fold change of 20.9 relative to normal esophageal tissues. But its effect and the molecular biological mechanisms on proliferation and invasion of EC cells remain unclear.AIM To investigate the effect of lnc RNA XLOC_001659 on esophageal squamous cell carcinoma(ESCC) cells and explore the molecular biological mechanisms involved.METHODS RT-q PCR assay was used to quantify the expression levels of lnc RNAXLOC-001659 and mi R-490-5 p. The proliferative capacity of the cells was determined using CCK8 and colony formation assays, and the effect of lnc RNAXLOC-001659 on the invasion of ESCC cells was determined by Transwell assay. Dualluciferase reporter assay was used to detect the target genes of lnc RNAXLOC-001659 and mi R-490-5 p.RESULTS The results of RT-q PCR showed that the expression of lnc RNAXLOC_001659 was upregulated in ESCC cells. CCK-8 assay showed that knockdown of lnc RNAXLOC_001659 significantly inhibited ESCC cell proliferation. Colony formation and Transwell invasion assays showed that knockdown of lnc RNAXLOC_001659 or overexpression of mi R-490-5 p significantly inhibited ESCC cell growth and invasion. Furthermore, lnc RNAXLOC_001659 acts as an endogenous sponge by competitively binding to mi R-490-5 p to downregulate mi R-490-5 p. Further results confirmed that mi R-490-5 p targeted PIK3 CA, and therecovery of PIK3 CA rescued lnc RNAXLOC_001659 knockdown or mi R-490-5 p overexpression-mediated inhibition of cell proliferation and invasion, which suggested the presence of an lnc RNAXLOC_001659/mi R-490-5 p/PIK3 CA regulatory axis.CONCLUSION Knockdown of lnc RNA XLOC_001659 inhibits proliferation and invasion of ESCC cells via regulation of mi R-490-5 p/PIK3 CA, suggesting that it may play a role in ESCC tumorigenesis and progression.     

槲皮素对食管癌Eca109细胞迁移侵袭及血管生成的影响

目的研究槲皮素(Que)对人食管癌Eca109细胞迁移侵袭及血管生成的影响。方法分别用5μg/mL、10μg/mL Que处理Eca109细胞,通过平板克隆形成实验、创伤愈合实验及Transwell实验观察其克隆形成能力以及迁移和侵袭能力的改变。制备Eca109肿瘤条件培养基,诱导人脐静脉内皮细胞CRL-1730迁移及成管,观察Que对其的影响。采用蛋白质免疫印迹法(Western blot)测定Que对Eca109细胞的血管内皮生长因子-A(VEGF-A)、基质金属蛋白酶2(MMP2)、MMP9蛋白表达的影响。结果 10μg/mL Que可显著抑制Eca109细胞的单细胞克隆形成能力(P0.05),而5μg/mL Que则不影响Eca109细胞的单细胞克隆形成能力(P0.05)。10μg/mL Que可抑制Eca109细胞的迁移和侵袭(P0.05),5μg/mL Que仅抑制Eca109细胞的侵袭(P0.05),但并不明显影响其迁移(P0.05)。5μg/mL、10μg/mL Que均可抑制Eca109肿瘤条件培养基诱导的CRL-1730细胞迁移和管腔形成(P均0.05),且10μg/mL Que的效果更明显。10μg/mL Que可明显降低VEGF-A、MMP2和MMP9的表达(P均0.05),5μg/mL Que仅降低MMP2的表达(P0.05)。结论 Que可以抑制Eca109细胞的迁移、侵袭及血管新生,并呈剂量依赖性。     

Angiopoietin-1 targeted RNA interference suppresses angiogenesis and tumor growth of esophageal cancer

AIM： To determine the inhibitory effect of the adenovirusbased angiopoietin-1 （Ang-1） targeted small interfering RNA expression system （Ad/Ang-1si） on the expression of the Ang-1 gene, cell growth and apoptosis in human esophageal cancer cell line Eca109. METHODS： siRNA-expressing adenovirus targeting Ang-1 gene was constructed using the Ad Easy System. Cultured Eca109 cells were transfected with Ad/Ang-1si （Eca109/Ang-1si）, and Ad/si was used to infect Eca109 cells as control （Eca109/si）. Ang-1 gene expression and concentration was determined with RT-PCR and ELISA, respectively. Human umbilical vein endothelial cell （HUVEC） migration and proliferation were analyzed. After s.c. injection into athymic nu/nu mice, the tumor growth, vessel density and apoptosis of each group was also determined. RESULTS： HUVEC migration induced by conditioned medium from Ang-1si-transfected Eca109 cells was significantly less than that induced by conditioned medium from Eca109 cells and control adenovirustransfected Eca109 cells. Furthermore, after s.c. injection into athymic nu/nu mice, the tumor growth and cell apoptosis of Ad/Ang-1si -expressing Eca109 cells was significantly lower than that of parental or control adenovirus-transfected cells. Vessel density assessed by CD31 immunohistochemical analysis and Ang-1 expression by RT-PCR were also decreased. CONCLUSION： The targeting Ang-1 may provide a therapeutic option for esophageal cancer.     

食管鳞癌中微小核糖核酸let-7的表达及病理生物学意义

目的 探讨微小RNA(miRNA)1et-7对食管鳞癌细胞增殖的影响及食管鳞癌组织中let-7表达水平与临床病理特征间的关系.方法 利用RNA干扰(RNAi)和细胞转染技术将食管鳞癌细胞Eca109分别转染入let-7、let-7抑制剂及随机序列.以正常培养的Eca109细胞为阴性对照组.噻唑蓝(MTT)比色法检测各组Eca109细胞的增殖情况.实时荧光定量聚合酶链反应(qRTPCR)检测各组细胞、45例食管鳞癌组织及其癌旁组织中let-7的表达水平,并分析其与食管鳞癌临床病理特征间的关系.结果 转染后72 h,转染let-7组吸光度(A)值较阴性对照组明显降低(P=0.005),转染let-7抑制剂组A值较阴性对照组明显升高(P=0.029).与阴性对照组let-7表达量比较,转染let-7组表达增加33%(1.33比1.00,P=0.039),转染let-7抑制剂组表达降低50%(0.50比1.00,P=0.014).食管鳞癌组织和癌旁组织中let-7相对表达量的比值为0.66±0.47,差异有统计学意义(P=0.001).汉族患者食管鳞癌组织中let-7相对表达量(0.48±0.43)低于哈萨克族(0.88±0.51,P=0.019).低分化食管鳞癌组织中let-7相对表达量(0.42±0.30)低于高分化食管鳞癌组织(0.84±0.38,P=0.015).有淋巴结转移者食管鳞癌组织中let-7相对表达量(0.50±0.35)低于无淋巴结转移者(0.80±0.52,P=0.032).结论 let-7对食管鳞癌的发生、发展起抑制作用,其表达水平与组织分化程度、淋巴结转移及民族相关.

Abstract：

Objective To estimate the effect of microRNA (miRNA) let-7 expression on human esophageal squamous cell carcinoma(ESCC) and the relationship between let-7 level and clinicopathological parameters. Methods ESCC cell line (Eca109) was transfected with let-7 or its inhibitor by RNAi and cell transfection techniques. Normal cultured Eca109 cell was served as negative control. The proliferation of Eca109 cell was detected by MTT. The expression of let-7 in Eca109 cells and 45 paired ESCC tissues and corresponding para-cancerous tissues were measured using real-time quantitative polymerase chain reaction (qRT-PCR). The relationship between let-7 level and clinicopathological parameters in patients with ESCC was analyzed. Results The A value of let-7 in Eca109 cells transfected with let-7 was lower than negative control (P=0.005), while it was higher in Eca109 cells transfected inhibitor than that in negative control 72 hours after transfection. In comparison with negative control, the expression of let-7 in Eca109 cells transfected with let-7 was increased 33% (1.33 vs 1.00,P=0. 039) and it was decreased 50% in Eca109 cells transfected with inhibitor (0.50 vs 1.00,P=0. 014). The ratio of let-7 expression in ESCC tissue and para-cancerous tissue was 0.66 ± 0.47 with significant differece (P= 0.001). Moreover, The level of let-7 expression in Han patients with ESCC was lower than Kazakh patients with ESCC (0.48±0.43 vs 0. 88±0.51,P=0. 019). The level of let-7 expression in poorly differentiated ESCC tissue was lower than well differentiated ESCC tissue (0.42±0.30 vs 0.84±0.38,P=0. 015). The level of let-7 expression in patients with lymph node metastasis was lower than those without lymph node metastasis (0.50±0.35vs 0. 80±0.52,P=0. 032) . Conclusion It is demonstrated that let-7 can inhibit the carcinogenesis and development of ESCC. The level of let-7 expression is associated with cell differentiation,lymph node metastasis and nationalities.     

Down-regulation of mi R-30a-3p/5p promotes esophageal squamous cell carcinoma cell proliferation by activating the Wnt signaling pathway

AIM To investigate the potential role of micro RNA-30 a(mi R-30 a) in esophageal squamous cell carcinoma(ESCC).METHODS Expression of mi R-30 a-3 p/5 p was analyzed using microarray data and fresh ESCC tissue samples. Both in vitro and in vivo assays were used to investigate the effects of mi R-30 a-3 p/5 p on ESCC cell proliferation. Furthermore,Kyoto Encyclopedia of Genes and Genomes analysis was performed to explore underlying mechanisms involved in ESCC,and then,assays were carried out to verify the potential molecular mechanism of mi R-30 a in ESCC.RESULTS Low expression of mi R-30 a-3 p/5 p was closely associated with advanced ESCC progression and poor prognosis of patients with ESCC. Knock-down of mi R-30 a-3 p/5 p promoted ESCC cell proliferation. Increased mi R-30 a-3 p/5 p expression inhibited the Wnt signaling pathway by targeting Wnt2 and Fzd2.CONCLUSION Down-regulation of mi R-30 a-3 p/5 p promotes ESCC cell proliferation by activating the Wnt signaling pathway through inhibition of Wnt2 and Fzd2.     

HIF-1α induces VE-cadherin expression and modulates vasculogenic mimicry in esophageal carcinoma cells

AIM: To investigate whether hypoxia inducible factor (HIF)-1α modulates vasculogenic mimicry (VM) by upregulating VE-cadherin expression in esophageal squamous cell carcinoma (ESCC).METHODS: Esophageal squamous cancer cell lines Eca109 and TE13 were transfected with plasmids harboring small interfering RNAs targeting HIF-1α or VE-cadherin. The proliferation and invasion of esophageal carcinoma cells were detected by MTT and Transwell migration assays. The formation of tubular networks of cells was analyzed by 3D culture in vitro. BALB/c nude mice were used to observe xenograft tumor formation. The relationship between the expression of HIF-1α and VE-cadherin, ephrinA2 (EphA2) and laminin5γ2 (LN5γ2) was measured by Western blot and real-time polymerase chain reaction.RESULTS: Knockdown of HIF-1α inhibited cell proliferation (32.3% ± 6.1% for Eca109 cells and 38.6% ± 6.8% for TE13 cells, P < 0.05). Both Eca109 and TE13 cells formed typical tubular networks. The number of tubular networks markedly decreased when HIF-1α or VE-cadherin was knocked down. Expression of VE-cadherin, EphA2 and LN5γ2 was dramatically inhibited, but the expression of matrix metalloproteinase 2 had no obvious change in HIF-1α-silenced cells. Knockdown of VE-cadherin significantly decreased expression of both EphA2 and LN5γ2 (P < 0.05), while HIF-1α expression was unchanged. The time for xenograft tumor formation was 6 ± 1.2 d for Eca109 cells and Eca109 cells transfected with HIF-1α Neo control short hairpin RNA (shRNA) vector, and 8.4 ± 2.1 d for Eca109 cells transfected with an shRNA against HIF-1α. Knockdown of HIF-1α inhibited vasculogenic mimicry (VM) and tumorigenicity in vivo.CONCLUSION: HIF-1α may modulate VM in ESCC by regulating VE-cadherin expression, which affects VM formation through EphA2 and LN5γ2.     

RNA干扰Akt对食管癌细胞株Eca109生物学特性的影响

目的:探讨RNA干扰沉默Akt对人食管鳞癌细胞体外增殖、迁移及血管生成拟态(VM)形成的影响.方法:应用倒置荧光显微镜观察Akt的干扰质粒转染食管癌细胞Eca109后绿色荧光蛋白的表达;采用Western blot方法检测Akt蛋白的表达;四甲基偶氮唑蓝(MTT)法检测转染前后细胞增殖能力的变化;Transwell方法...     

Effect of S1P5 on proliferation and migration of human esophageal cancer cells

AIM:To investigate the sphingosine 1phosphate (S1P) receptor expression profile in human esophageal cancer cells and the effects of S1P5 on proliferation and migration of human esophageal cancer cells. METHODS: S1P receptor expression profile in human esophageal squamous cell carcinoma cell line Eca109 was detected by semiquantitative reverse trans cription polymerase chain reaction. Eca109 cells were stably transfected with S1P5EGFP or controlEGFP constructs. The relation between the responses of cell prol...     

血管内皮钙黏附素下调对食管鳞癌细胞血管生成拟态、增殖和凋亡的影响

背景：血管内皮钙黏附素（VE-cad）作为血管生成拟态的重要调控分子在多种高侵袭性肿瘤中均存在表达,参与肿瘤的发生、发展过程。前期研究发现食管鳞癌细胞中亦存在VE—cad表达。目的：探讨微小RNA（miRNA）干扰技术下调VE-cad对食管鳞癌细胞血管生成拟态形成、细胞增殖和凋亡的影响及其可能机制。方法：将已成功构建的VE—cadmiRNA干扰质粒稳定转染Eca109、TE13细胞,同时设置阴性对照组（转染空质粒）和空白对照组（未转染）。荧光显微镜观察单克隆转染效率,三维培养观察细胞管腔样结构形成的能力,RT—PCR和蛋白质印迹法分别检测VE-cad、EphA2、LN5γ2 mRNA和蛋白表达,MTT法和流式细胞术分别检测细胞增殖和凋亡。结果：荧光显微镜显示Eca109、TE13细胞稳定转染效率均达90％以上。与阴性对照组和空白对照组相比,干扰组细胞管腔样结构数目明显减少（P〈0．01）,VE—cad、EphA2、LN5γ2mRNA和蛋白表达明显受抑（P〈0．01）,细胞增殖能力明显下降（P〈0．05）,凋亡率明显增高（P〈0．05）。结论：miRNA干扰技术能有效抑制食管鳞癌细胞Eca109、TE13的VE-cad表达。VE—cad通过下调EphA2和LN5γ2表达抑制血管生成拟态的体外形成,并影响细胞增殖和凋亡。VE—cad可能成为食管鳞癌分子靶向治疗的新靶点。     

RNA干扰HIF-1α对食管鳞癌血管生成拟态的影响

背景:研究表明大量高度恶性肿瘤组织中存在血管生成拟态(VM),其分子机制已形成相关假说,但确切机制和关键信号通路尚未明确。目的:探讨缺氧诱导因子(HIF)-1α在食管鳞癌VM形成中的作用。方法:设计合成3种HIF-1α-siRNA质粒,测序后瞬时转染293T细胞,蛋白质印迹法鉴定质粒的干扰效果。将筛选出的pGCsi-HIF3质粒稳定转染食管鳞癌细胞株Eca109和TE13,以蛋白质印迹法检测干扰效果,三维培养法观察VM形成情况,蛋白质印迹法检测VE-cadherin、EphA2、LN5γ2和MMP2蛋白表达。结果:成功构建了3个靶位的质粒,其中pGCsiHIF3的干扰效果最好。pGCsi-HIF3稳定转染食管鳞癌细胞株Eca109和TE13后,与对照组相比,HIF-1α表达明显降低,细胞体外管道形成能力被明显抑制(P0.05)。常氧下转染组细胞中VE-cadherin、EphA2、LN5γ2均显著下调(P0.05),MMP2表达无明显差异,且缺氧条件下上述指标蛋白表达无明显增加。结论:Eca109和TE13细胞能形成管状结构,HIF-1α可能通过调节VE-cadherin、EphA2、LN5γ2等的表达而调节食管鳞癌VM的形成。     

Role of stress-activated MAP kinase P38 in cisplatin- and DTT-induced apoptosis of the esophageal carcinoma cell line Eca109

AIM: To study the role of P38 kinase in esophageal cancer cell apoptosis induced by genotoxin, cisplatin and the unfolded protein response (UPR) inducer, dithiothreitol (DTT). METHODS: Esophageal carcinoma cell line Eca109 was cultured in RPMI 1640 medium to 70% confluency and treated with either cisplatin, DTT, or cisplatin plus DTT in the presence or absence of P38 inhibitor, SB203580. The untreated cells served as the control. The esophageal carcinoma cell apoptosis was detected by agarose gel DNA ladder analysis and quantified by flow cytometry. The P38 phosphorylation was detected by immunohis-tochemistry using antibodies specific to phosphorylated P38 protein. RESULTS: (1) Both cisplatin and DTT induced apoptosis in the esophageal cancer cell line Eca109 as shown by DNA ladder formation; (2) As detected by antibodies specific for the phosphorylated P38 protein (p-P38), both cisplatin and DTT treatments activated the stress-activated enzyme, MAP kinase P38. The number of positive cells was about 50% for the treatment groups, comparing to that of 10% for untreated group. DTT treatment, but not cisplatin treatment, induces nuclear localization of p-P38; (3) As measured by flow cytometry, inhibition of P38 activity by SB203580 blocks DTT- and cisplatin-induced apoptosis. The rates for DTT, cisplatin, and DTT plus cisplatin-induced apoptosis were 16.8%, 17.1%, and 21.4%, respectively. Addition of the SB compound during the incubation reduced the apoptotic rate to about 7.6% for all the treatment groups, suggesting that P38 activation is essential for cisplatin- and DTT-induced apoptosis in Eca109 cells. CONCLUSION: (1) Both DTT and cisplatin were able to induce apoptosis in esophageal cancer cell line Eca109; (2) P38 MAP kinase is essential for DTT- and cisplatin- induced apoptosis in Eca109 cells; (3) P38 activation may be the common signaling component relaying the multiple upstream signaling events to the downstream cell death program.     

新疆哈萨克族食管鳞癌中微小RNA let-7的表达及病理生物学意义

目的探讨微小RNA（miRNA）let-7在食管鳞癌细胞及组织中的表达,及let-7与食管鳞癌临床病理的关系。方法在细胞水平,运用实时荧光定量聚合酶链反应（real-time quantitative PCR,qRT-PCR）检测let-7在正常食管鳞状上皮细胞Heepic及食管鳞癌细胞CaES-17、Eca109和KYSE-150中的表达差异;在组织水平,采用qRT-PCR技术检测let-7在15对哈萨克族食管鳞癌组织和癌旁正常组织中的表达,并分析其与食管鳞癌浸润、转移等临床病理的关系。结果 qRT-PCR结果显示,let-7在3个食管鳞癌细胞系中的表达明显低于在正常食管鳞状上皮细胞Heepic中的表达,let-7在食管鳞癌组织中的表达明显低于其在癌旁正常组织中的表达,其相对表达量比值为0.79±0.56,差异有统计学意义（P〈0.05）;let-7在不同性别、分化程度、大体分型、浸润深度及淋巴结转移之间的相对表达量比值均无统计学差异（P〉0.05）。结论 Let-7在正常食管鳞状上皮细胞和食管鳞癌细胞中均有表达,但在食管鳞癌细胞中呈低表达;let-7在食管鳞癌组织和正常食管鳞状上皮组织中均有表达,但在癌组织中呈显著低表达;哈萨克族食管鳞癌患者let-7低表达与其临床病理参数之间无显著相关性;let-7对哈萨克族食管鳞癌的发生起抑制作用,是食管鳞癌的潜在分子标记物。     

High Expression of BCCIP β Can Promote Proliferation of Esophageal Squamous Cell Carcinoma

Background

BCCIP was originally identified as a BRCA2 interacting protein in humans and Ustilago maydis. It had low expression in some human cancer tissues. However, recent research indicated that many caretaker genes are also necessary for cell viability and their expression could contribute to tumor progression.

Aim

To characterize whether BCCIP is a caretaker gene in esophageal squamous cell carcinoma (ESCC).

Methods

Western blotting and immunohistochemistry were used to measure the expression of BCCIP β. In vitro studies were used to verify the effects of BCCIP β in Eca109 cells.

Results

Expression of BCCIP β was notably higher in tumor tissues of ESCC and Eca 109 cells. Meanwhile, the immunohistochemistry stain revealed that BCCIP β was positively correlated with clinical pathologic variables such as tumor size and tumor grade, as well as Ki-67, and prompted poor prognosis. In vitro studies such as starvation and refeeding assay along with BCCIP β-shRNA transfection assay demonstrated that BCCIP β expression promoted proliferation of ESCC cells. In addition, BCCIP β downregulation by silencing RNA significantly decreased the rate of colony formation, alleviated cellular apoptosis and increased the chemosensitivity of cisplatin.

Conclusions

This research first put forward that BCCIP β is an oncogene in human ESCC and contributes to the poor outcome of the deadly disease.

     

Exosomal mi R-182 regulates the effect of RECK on gallbladder cancer

BACKGROUND As the most common biliary malignancy,gallbladder cancer(GC)is an elderlybiased disease.Although extensive studies have elucidated the molecular mechanism of microRNA 182(miR-182)and reversion-inducing-cysteine-rich protein with kazal motifs(RECK)in various cancers,the specific role of exosomal miR-182 and RECK in GC remains poorly understood.AIM To explore the relationship between exosomal miR-182/RECK and metastasis of GC.METHODS Paired GC and adjacent normal tissues were collected from 78 patients.Quantitative polymerase chain reaction was employed to detect miR-182 and exosomal miR-182 expression,and Western blotting was conducted to determine RECK expression.In addition,the effects of exosomal miR-182/RECK on the biological function of human GC cells were observed.Moreover,the double luciferase reporter gene assay was applied to validate the targeting relationship between miR-182 and RECK.RESULTS Compared with normal gallbladder epithelial cells,miR-182 was highly expressed in GC cells,while RECK had low expression.Exosomal miR-182 could be absorbed and transferred by cells.Exosomal miR-182 inhibited RECK expression and promoted the migration and invasion of GC cells.CONCLUSION Exosomal miR-182 can significantly promote the migration and invasion of GC cells by inhibiting RECK;thus miR-182 can be used as a therapeutic target for GC.     

磁性纳米控释紫杉醇对食管癌Eca109细胞株生长的影响

目的:观察不同浓度磁性纳米控释紫杉醇对食管癌细胞Eca109的影响及与不同化疗药物的对比.方法:取对数生长期的食管癌Eca109细胞作细胞增殖抑制实验,实验组分别给予不同浓度的磁性纳米控释紫杉醇和5-氟尿嘧啶、泰素,同时设立二甲基亚砜(DMSO)和RPMI1640液对照,测定24,48,72h三个时间段的吸光度值,计算抑制率.经不同浓度的磁性纳米控释紫杉醇作用72h后,用电镜观察细胞超微结构,同时用流式细胞仪测定细胞周期和细胞凋亡.结果:MTT实验显示磁性纳米控释紫杉醇可抑制食管癌细胞增殖,与5-氟尿嘧啶,泰素相比,具有缓释性(P<0.01);电镜可发现药物作用组细胞核固缩、解聚以及凋亡小体;流式细胞仪检测显示G1峰前有明显的凋亡峰;细胞周期分析提示磁性纳米控释紫杉醇可将Eca109细胞阻滞于G2-M期,且与浓度相关.结论:磁性纳米控释紫杉醇对人食管癌细胞Eca109的生长有明显的抑制作用,使细胞分裂阻滞于G2-M期,并诱导细胞凋亡,且具有缓释效果.     

Bile salts inhibit growth and induce apoptosis of human esophageal cancer cell line

AIM: To explore the effect of six bile salts, including glycoc holate (GC), glycochenodeoxycholate (GCDC), glycodeoxy cholate (GDC), taurocholate (TC), taurochenodeoxycholate (TCDC), taurodeoxycholate (TDC), and two bile acids including cholic acid (CA) and deoxycholic acid (DCA) on esophageal cancer Ecal09 cell line. METHODS: Eca109 cells were exposed to six bile salts, two bile acids and the mixed bile salts at different concentrations for 24-72 h. 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to detect the cell proliferation. Apoptotic morphology was observed by phase-contrast video microscopy and deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Sub-G1 DNA fragmentations and early apoptosis cells were assayed by flow cytometry (FCM) with propidium iodide (PI) staining and annexin V-FITC conjugated with PI staining. Apoptosis DNA ladders on agarose were observed. Activation of caspase-3 was assayed by FCM with FlTC-conjugated monoclonal rabbit anti-active caspase-3 antibody and expressions of Bcl-2 and Bax proteins were examined immunocytochemically in 500 μmol/L-TC-induced apoptosis cells. RESULTS: Five bile salts except for GC, and two bile acids and the mixed bile salts could initiate growth inhibition of Ecal09 cells in a dose- and time-dependent manner. TUNEL, FCM, and DNA ladder assays all demonstrated apoptosis induced by bile salts and bile acids at 500 μmol/L, except for GC. Early apoptosis cell percentages in Eca109 cells treated with GCDC, GDC, TC, TCDC, TDC, CA at 500 μmol/L for 12 h, DCA at 500 μmol/L for 6 h, and mixed bile salts at 1 000 μmol/L for 12 h were 7.5%, 8.7%, 14.8%, 8.9%, 7.8%, 9.3%, 22.6% and 12.5%, respectively, all were significantly higher than that in control (1.9%). About 22% of the cell population treated with TC at 500 μmol/L for 24 h had detectable active caspase-3, and were higher than that in the control (1%). Immunocytochemical assay suggested that TC down-regulated Bcl-2 protein level and up-regulated Bax protein level. CONCLUSION: GCDC, GDC, TC, TCDC, TDC, CA and DCA, except for GC, can inhibit growth and induce apoptosis of esophageal cancer Ecal09 cells. Activation of caspase-3, decreased Bcl-2 protein and increased Bax protein are involved in TC-induced apoptosis of Ecal09 cells.     

Experimental and clinicopathologic study on the relationship between transcription factor Egr-1 and esophageal carcinoma

AIM: To observe the growth suppression effect of exogenous introduction of early growth response gene-1 (Egr-1 gene) on esophageal carcinoma tissue as well as on esophageal carcinoma cell line Eca109 and to explore the potential application of Egr-1 gene in gene therapy of tumor. METHODS: Eukaryotic expression vector of PCMV-Egr-1 plasmid was introduced into Eca109 cell line which expressed no Egr-1 protein originally with lipofectamine transfection method. The introduction and expression of PCMV-Egr-1 plasmid into Eca109 cell line was confirmed by G418 selection culture, PCR amplification of neogene contained in the vector, Western blot analysis and immunocytochemical analysis. The cell growth curve, soft agar colony formation rate and tumorigenicity in SCID mice were examined to demonstrate the growth suppression effect of exogenous Egr-1 gene on Eca109 cell line. The Egr-1 mRNA and Egr-1 protein were also detected in 50 surgical specimens of esophageal carcinoma by in situ hybridization and immunohistochemistry. RESULTS: Exogenous Egr-1 gene was introduced successfully into Eca109 cell line and expressed Egr-1 protein stably. The transfected Eca109 cell line grew more slowly than control Eca109 as shown by cell growth curves, the soft agar colony formation rate (4.0% vs 6.9%, P < 0.01) and the average growth rate of tumor in SCID mice (35.5 +/- 7.6 vs 65.8 +/- 7.6, P < 0.05). The expression level of Egr-1 mRNA and protein significantly increased in dysplastic epithelia adjacent to cancer rather than in cancer tissues (65.8% vs 20.0% by ISH and 57.9% vs 0.01). CONCLUSION: Exogenous Egr-1 gene shows the strong effect of growth inhibition in Eca109 cell line. Egr-1 in the cancer tissue shows down-regulated expression that supports the inhibited function of Egr-1 in cancer growth and suggests Egr-1 may have an important role in gene therapy of esophageal carcinoma.