Staufen基因在结直肠癌组织中的表达

为研究甲基化差异相关基因Staufen在结直肠癌不同组织中的表达情况,采用RT-PCR和免疫组织化学等方法在结直肠癌病人中检测Staufen基因在腺癌、癌旁粘膜和相应远端切缘正常组织中的表达。研究发现,在mRNA水平上,远端切缘正常组织中Staufen基因的表达水平显著高于癌旁粘膜和腺癌（P<0.05）;从正常组织、癌旁粘膜到腺癌,Staufen基因的表达有降低的趋势;未发现性别、年龄、肿瘤部位（结肠/直肠）、分化程度、淋巴结转移等临床病理因素与Staufen基因的表达有关（P均>0.05）。正常组织与腺癌组织的Staufen蛋白的表达水平显著高于癌旁粘膜（P<0.05）,而正常组织与腺癌组织之间未发现有统计学差别（P>0.05）。结果表明,Staufen基因在癌旁粘膜和肿瘤中有低表达的趋势,该基因可能在结直肠癌的发生、发展中起作用。     

Increased expression of one of two adenosine deaminase alleles in a human choriocarcinoma cell line following selection with adenine nucleosides

JEG-3 is a human choriocarcinoma cell line characterized by low levels of adenosine deaminase expression. For the purpose of studying adenosine deaminase gene regulation in the JEG-3 cells, we attempted to select variant cells having increased adenosine deaminase expression. This was accomplished by selecting cells for resistance to the cytotoxic adenosine analogs 9-beta-D-arabinofuranosyl adenine (ara-A) or 9-beta-D-xylofuranosyl adenine (xyl-A), both of which could presumably be detoxified by the action of adenosine deaminase. Single step high dose selection was ineffective in obtaining cells with increased adenosine deaminase. However, multistep selection using either ara-A or xyl-A resulted in cell populations with increased adenosine deaminase activity. Removal of selective pressure resulted in decreased adenosine deaminase levels. Subclones of xyl-A-resistant cells belonged to one of three phenotypic classes characterized by either elevated adenosine deaminase levels, decreased adenosine kinase levels, or both of these features. One subclone (A3-1A7) with unaltered adenosine kinase expression showed a 20-fold increase in adenosine deaminase expression. Further selection of this subclone for increasing xyl-A resistance resulted in an additional 2-fold increase in adenosine deaminase expression, followed by loss of adenosine kinase expression. These adenosine kinase-deficient cells showed no subsequent increase in adenosine deaminase expression in response to further xyl-A selection pressure. These results confirmed that xyl-A toxicity was mediated through its phosphorylated form and indicated that resistance may result from increased adenosine deaminase levels and/or adenosine kinase deficiency. The increased adenosine deaminase expression of the A3-1A7 subclone was exclusively in the ADA 2 allelic form. However, cell fusion experiments between A3-1A7 cells and mouse C1-1D cells established the existence of functional copies of both ADA 1 and ADA 2 allelic genes in the A3-1A7 cells. The increased expression of only one of the two functional ADA alleles, the requirement for a stepwise selection protocol to obtain cells with increased adenosine deaminase, and the instability of the adenosine deaminase phenotype in the absence of selective pressure suggest that the alteration of adenosine deaminase phenotype in the drug-resistant cells was the result of adenosine deaminase gene amplification.     

Effect of RSK4 on biological characteristics of colorectal cancer

Background

This study aimed to investigate the expression of P90 Ribosomal Protein S6 kinase 4 (RSK4) in colorectal cancer cells and its biological function.

Methods

We selected early SW480 and HCT116 colorectal cancer cell lines, using Lipofectamine? 2000 transfection reagent carrying RSK4 gene transfected into cells to establish the colorectal cancer cell lines with high expression of RSK4. RT-PCR and western blot (WB) analysis confirmed RSK4 expression in SW480 and HCT116 cancer cell lines. We used methylthiazoltetrazolium (MTT) assay and flow cytometry to detect the proliferation of colorectal cancer cells. After transfection of RSK4, the effect of RSK4 on the RNA levels associated with epithelial–mesenchymal transition (EMT) of colorectal cancer cells was analyzed by real-time fluorescence quantitative PCR and the expression of EMT-related protein was detected by WB analysis.

Results

After transfection of RSK4 overexpression, the MTT assay detected that RSK4 could significantly inhibit the growth of colorectal cancer cells in vitro; flow cytometry detected that S-phase cells decreased significantly, and G0/1 cells increased significantly (P?<?0.05). The invasion ability of SW480 and HCT116 cells transfected with RSK4 was markedly lower than that in the control group, and the difference was statistically significant (P?<?0.05). Fluorescent quantitative PCR and WB analysis showed that the expression of EMT-associated molecular E-cadherin was remarkably increased and the expression of Snail was significantly decreased (P?<?0.01).

Conclusion

RSK4 gene in colorectal cancer cell lines with low expression of RSK4 after transfection can inhibit the growth and invasion of tumor cells. RSK4 gene may inhibit EMT and inhibit metastasis of colorectal cancer cells, may be a potential tumor suppressor gene and inhibit tumor distant metastasis, and may provide the biological basis for new therapeutic targets.

     

结直肠癌患者血浆甲基化Sept9基因的表达及临床意义

目的:探讨甲基化Sept9基因在结直肠癌患者血浆中的表达及临床意义。方法:选择2015年1月~2017年3月经陕西省人民医院病理证实的结直肠癌患者87例(结直肠癌组)、结直肠息肉患者79例(结直肠息肉组)、健康体检者93例(健康对照组)作为研究对象,采用实时荧光定量聚合酶链式反应(PCR)技术检测其外周血血浆Sept9基因甲基化情况,比较三组甲基化Sept9基因阳性表达率,分析甲基化Sept9基因阳性表达与结直肠癌病理特征的关系。结果:血浆甲基化Sept9基因在结直肠癌组、结直肠息肉组、健康对照组的阳性表达率分别为71.26%(62/87)、5.06%(4/79)、3.23%(3/93),差异有统计学意义(P0.05);血浆甲基化Sept9基因阳性表达与结直肠癌患者的性别、年龄、肿瘤部位、病理分型、血管侵犯、神经侵犯无关(P0.05),与肿瘤最大径、浸润深度、分化程度、淋巴结转移、TNM分期有关(P0.05);结直肠癌患者血浆甲基化Sept9基因阳性表达率为71.26%(62/87),高于血清CEA的54.02%(47/87)、CA199的35.63%(31/87)、CA724的33.33%(29/87)、CA125的21.84%(19/87),差异有统计学意义(P0.05)。结论:结直肠癌患者外周血血浆甲基化Sept9基因呈高表达状态,早期检测甲基化Sept9基因表达水平在结直肠癌的诊断及病情评估中有重要意义。     

抑癌基因DLC-1在结肠癌细胞sw480中表达的研究

目的:初步探讨DLC-1基因在结肠癌细胞sw480中的表达改变及其可能机制;方法:采用RT-PCR和Western blot分析结肠癌细胞CaCo2、sw480的DLC-1表达情况;应用去甲基化药物5—氮杂胞苷处理DLC-1基因阴性表达的细胞株,观察用药前后该细胞DLC-1基因的表达水平、细胞周期、细胞增殖力和侵袭力的影响。结果:CaCo2细胞高表达DLC-1 mRNA,而sw480则呈现表达缺失。经去甲基化药物5—氮杂胞苷处理sw480后,DLC-1 mRNA恢复表达,比较用药前后sw480细胞增殖力下降、细胞周期被阻滞在G2期、细胞侵袭力减弱。结论:DLC-1基因可影响结肠癌细胞sw480的增殖能力和侵袭力,并使结肠癌细胞sw480细胞周期阻滞于G2期,DNA甲基化可能是导致DLC-1在sw480细胞中的失活的一个重要原因。     

ATM-Deficient Colorectal Cancer Cells Are Sensitive to the PARP Inhibitor Olaparib

The ataxia telangiectasia mutated (ATM) protein kinase plays a central role in the cellular response to DNA damage. Loss or inactivation of both copies of the ATM gene (ATM) leads to ataxia telangiectasia, a devastating childhood condition characterized by neurodegeneration, immune deficiencies, and cancer predisposition. ATM is also absent in approximately 40% of mantle cell lymphomas (MCLs), and we previously showed that MCL cell lines with loss of ATM are sensitive to poly-ADP ribose polymerase (PARP) inhibitors. Next-generation sequencing of patient tumors has revealed that ATM is altered in many human cancers including colorectal, lung, prostate, and breast. Here, we show that the colorectal cancer cell line SK-CO-1 lacks detectable ATM protein expression and is sensitive to the PARP inhibitor olaparib. Similarly, HCT116 colorectal cancer cells with shRNA depletion of ATM are sensitive to olaparib, and depletion of p53 enhances this sensitivity. Moreover, HCT116 cells are sensitive to olaparib in combination with the ATM inhibitor KU55933, and sensitivity is enhanced by deletion of p53. Together our studies suggest that PARP inhibitors may have potential for treating colorectal cancer with ATM dysfunction and/or colorectal cancer with mutation of p53 when combined with an ATM kinase inhibitor.     

DLC-1基因表达对结肠癌细胞侵袭转移能力的影响

目的:研究DLC-1基因对结肠癌细胞侵袭迁移能力的影响.方法:将DLC-1 shRNA(短发夹状RNA,short hairpin RNA)序列克隆到质粒pGCsi-U6/Neo载体,采用脂质体介导的转染方法将构建的DLC-1 shRNA表达质粒转入结肠癌细胞系LoVo细胞.采用RT-PCR技术和Western Blot技术分别检测LoVo细胞中DLC-1mRNA和蛋白表达水平的变化.Transwell小室人工重组基底膜侵袭转移实验观察LoVo细胞侵袭迁移能力的改变.结果:结肠癌细胞系LoVo细胞表达DLC-1分子.所构建质粒表达载体能有效地干扰LoVo细胞DLC-1 mRNA和蛋白质表达水平;Transwell小室人工重组基底膜侵袭转移实验结果显示,转染后LoVo细胞侵袭转移能力明显增强(p＜0.05).结论:结肠癌细胞系LoVo细胞表达DLC-1基因,应用RNAi技术可特异性降低其表达.DLC-1的表达水平与结肠癌细胞侵袭转移相关.     

结直肠癌组织RSK4、p53蛋白的表达及临床病理意义

目的:探讨结直肠癌组织中P90核糖体S6激酶4(RSK4)蛋白、p53蛋白的表达及其临床病理意义。方法:选取我院病理科2014年1月~2016年5月既往收集的结直肠癌手术后标本70例及同期结直肠癌癌旁组织30例,采用免疫组化染色检测两组标本中RSK4蛋白、p53蛋白的表达情况,并分析其与结肠癌患者临床病理特征的相关性。结果:结直肠癌组织中RSK4蛋白、p53蛋白的阳性表达率分别为20.00%、55.71%,而癌旁组织中RSK4蛋白、p53蛋白阳性表达率分别为53.33%、10.00%,两组比较差异均具有统计学意义(P0.05)。Ⅰ期+Ⅱ期、高分化和中分化结直肠癌组织RSK4蛋白的阳性表达率显著高于Ⅲ期、低分化结直肠癌(P0.05);Ⅰ期+Ⅱ期、浸润深度(T1、T2)、未发生淋巴结转移的结直肠癌组织中p53蛋白阳性表达率显著的低于Ⅲ期、浸润深度(T3、T4)、发生淋巴结转移的结肠癌组织(P0.05)。结论:结直肠癌组织中RSK4蛋白表达下调、p53蛋白表达上调,二者可能与结直肠癌的发生和发展有关,并可能作为结肠癌诊断和预后评估的参考指标。     

Large-scale profiling and identification of potential regulatory mechanisms for allelic gene expression in colorectal cancer cells

Allelic variation in gene expression is common in humans and this variation is associated with phenotypic variation. In this study, we employed high-density single nucleotide polymorphism (SNP) chips containing 13,900 exonic SNPs to identify genes with allelic gene expression in cells from colorectal cancer cell lines. We found 2 monoallelically expressed genes (ERAP2 and MYLK4), 32 genes with an allelic imbalance in their expression, and 13 genes showing allele substitution by RNA editing. Among a total of 34 allelically expressed genes in colorectal cancer cells, 15 genes (44.1%) were associated with cis-acting eQTL, indicating that large portions of allelically expressed genes are regulated by cis-acting mechanisms of gene expression. In addition, potential regulatory variants present in the proximal promoter regions of genes showing either monoallelic expression or allelic imbalance were not tightly linked with coding SNPs, which were detected with allelic gene expression. These results suggest that multiple rare variants could be involved in the cis-acting regulatory mechanism of allelic gene expression. In the comparison with allelic gene expression data from Centre d'Etude du Polymorphisme Humain (CEPH) family B cells, 12 genes showed B-cell specific allelic imbalance and 1 noncoding SNP showed colorectal cancer cell-specific allelic imbalance. In addition, different patterns of allele substitution were observed between B cells and colorectal cancer cells. Overall, our study not only indicates that allelic gene expression is common in colorectal cancer cells, but our study also provides a better understanding of allele-specific gene expression in colorectal cancer cells.     

大肠癌转移相关分子标签的筛选

目的:筛选与转移相关的大肠癌分子标签.方法:本文通过对大肠癌表达谱数据进行分析,按照表达谱中大肠癌转移情况,组织学分化程度以及患者生存时间进行显著性分析,将与大肠癌转移相关的具有显著性意义的基因群进行聚类,通过主成分分析以及自组织映射的方法计算出差异表达基因中,起着主体分类作用的基因群.结果:筛选出与肿瘤组织分化程度以及患者生存时间相关的差异表达基因,进行功能富集,并筛选出了一批与大肠癌转移密切相关的重要基因,这些基因对大肠癌早期诊断,及时治疗,预后评估有着重要意义.结论:细胞代谢,趋化因子信号通路和细胞因子受体等分子事件与大肠癌分化程度密切相关,是否发生转移与大肠癌的预后生存期密切相关.     

Tazarotene-induced gene 1 inhibits prostaglandin E2-stimulated HCT116 colon cancer cell growth

Background  

The tazarotene-induced gene 1 (TIG1) is a putative tumor suppressor gene. We have recently demonstrated both TIG1A and TIG1B isoforms inhibited cell growth and induced the expression of G protein-coupled receptor kinase 5 (GRK5) in colon cancer cells. Because elevated prostaglandin E2 (PGE2) signaling plays a significant role in colorectal carcinogenesis, the objective of this study was to explore the effect of TIG1 on PGE2-induced cellular proliferation and signaling in colon cancer cells.     

The deoxycholic acid targets miRNA-dependent CAC1 gene expression in multidrug resistance of human colorectal cancer

There is evidence indicating that bile acid is a promoter of colorectal cancer. Deoxycholic acid modifies apoptosis and proliferation by affecting intracellular signaling and gene expression. We are interested in revealing the relationship between deregulated miRNAs and deoxycholic acid in colorectal cancer development. We found that miR-199a-5p was expressed at a low level in human primary colonic epithelial cells treated with deoxycholic acid compared with control, and miR-199a-5p was significantly down-regulated in colorectal cancer tissues. The miR-199a-5p expression in colorectal cancer cells led to the suppression of tumor cell growth, migration and invasion. We further identified CAC1, a cell cycle-related protein expressed in colorectal cancer, as a miR-199a-5p target. We demonstrated that CAC1 is over-expressed in malignant tumors, and cellular CAC1 depletion resulted in cancer growth suppression. HCT-8 cells transfected with a miR-199a-5p mimic or inhibitor had a decrease or increase in CAC1 protein levels, respectively. The results of the luciferase reporter gene analysis demonstrated that CAC1 was a direct miR-199a-5p target. The high miR-199a-5p expression and low CAC1 protein expression reverse the tumor cell drug resistance. We conclude that miR-199a-5p can regulate CAC1 and function as a tumor suppressor in colorectal cancer. Therefore, the potential roles of deoxycholic acid in carcinogenesis are to decrease miR-199a-5p expression and/or increase the expression of CAC1, which contributes to tumorigenesis in patients with CRC. These findings suggest that miR-199a-5p is a useful therapeutic target for colorectal cancer.     

MicroRNA‐1271 suppresses the proliferation and invasion of colorectal cancer cells by regulating metadherin/Wnt signaling

Recent studies have reported an important role for microRNA‐1271 (miR‐1271) in tumorigenesis. However, the role of miR‐1271 in colorectal cancer remains unknown. Here, we found that miR‐1271 was significantly decreased in colorectal cancer tissues and cell lines. Overexpression of miR‐1271 inhibited cell proliferation, colony formation, cell invasion, and induced cell cycle arrest in colorectal cancer cells. Metadherin (MTDH) was identified as a target gene of miR‐1271. Moreover, miR‐1271 negatively regulated MTDH expression in colorectal cancer cells and reversely correlated with MTDH expression in colorectal cancer specimens. Additionally, miR‐1271 also regulated the activation of Wnt signaling in colorectal cancer cells. The restoration of MTDH expression significantly reversed the antitumor effect of miR‐1271 in colorectal cancer cells. These findings indicate an important role for miR‐1271/MTDH in the tumorigenesis of colorectal cancer, and suggest that miR‐1271 may be a novel therapeutic target for colorectal cancer.     

Neuropilin-2 expression promotes TGF-β1-mediated epithelial to mesenchymal transition in colorectal cancer cells

Neuropilins, initially characterized as neuronal receptors, act as co-receptors for cancer related growth factors and were recently involved in several signaling pathways leading to cytoskeletal organization, angiogenesis and cancer progression. Then, we sought to investigate the ability of neuropilin-2 to orchestrate epithelial-mesenchymal transition in colorectal cancer cells. Using specific siRNA to target neuropilin-2 expression, or gene transfer, we first observed that neuropilin-2 expression endows HT29 and Colo320 for xenograft formation. Moreover, neuropilin-2 conferred a fibroblastic-like shape to cancer cells, suggesting an involvement of neuropilin-2 in epithelial-mesenchymal transition. Indeed, the presence of neuropilin-2 in colorectal carcinoma cell lines was correlated with loss of epithelial markers such as cytokeratin-20 and E-cadherin and with acquisition of mesenchymal molecules such as vimentin. Furthermore, we showed by surface plasmon resonance experiments that neuropilin-2 is a receptor for transforming-growth factor-β1. The expression of neuropilin-2 on colon cancer cell lines was indeed shown to promote transforming-growth factor-β1 signaling, leading to a constitutive phosphorylation of the Smad2/3 complex. Treatment with specific TGFβ-type1 receptor kinase inhibitors restored E-cadherin levels and inhibited in part neuropilin-2-induced vimentin expression, suggesting that neuropilin-2 cooperates with TGFβ-type1 receptor to promote epithelial-mesenchymal transition in colorectal cancer cells. Our results suggest a direct role of NRP2 in epithelial-mesenchymal transition and highlight a cross-talk between neuropilin-2 and TGF-β1 signaling to promote cancer progression. These results suggest that neuropilin-2 fulfills all the criteria of a therapeutic target to disrupt multiple oncogenic functions in solid tumors.     

DNA methylation down-regulates CDX1 gene expression in colorectal cancer cell lines

CDX1 is a homeobox protein that inhibits proliferation of intestinal epithelial cells and regulates intestine-specific genes involved in differentiation. CDX1 expression is developmentally and spatially regulated, and its expression is aberrantly down-regulated in colorectal cancers and colon cancer-derived cell lines. However, very little is known about the molecular mechanism underlying the regulation of CDX1 gene expression. In this study, we characterized the CDX1 gene structure and identified that its gene promoter contained a typical CpG island with a CpG observed/expected ratio of 0.80, suggesting that the CDX1 gene is a target of aberrant methylation. Alterations of DNA methylation in the CDX1 gene promoter were investigated in a series of colorectal cancer cell lines. Combined Bisulfite Restriction Analysis (COBRA) and bisulfite sequencing analysis revealed that the CDX1 promoter is methylated in CDX1 non-expressing colorectal cancer cell lines but not in human normal colon tissue and T84 cells, which express CDX1. Treatment with 5'-aza-2'-deoxycytidine (5-azaC), a DNA methyltransferase inhibitor, induced CDX1 expression in the colorectal cancer cell lines. Furthermore, de novo methylation was determined by establishing stably transfected clones of the CDX1 promoter in SW480 cells and demethylation by 5-azaC-activated reporter gene expression. These results indicate that aberrant methylation of the CpG island in the CDX1 promoter is one of the mechanisms that mediate CDX1 down-regulation in colorectal cancer cell lines.