JIB-04通过调控细胞周期蛋白抑制结肠癌细胞增殖

已有报道显示,组蛋白去甲基化酶抑制剂JIB-04(Jumonji histone demethylase inihibitor,JIB-04)抑制肿瘤的发生发展,但其具体作用机制仍不清楚。本研究以结肠癌细胞HCT116和HT29为对象,探讨组蛋白去甲基化酶抑制剂JIB-04对结肠癌细胞增殖的影响,并阐述其作用机制。MTT和平板克隆形成实验显示,JIB-04以浓度和时间依赖的方式降低HCT116和HT29细胞的增殖能力,半数抑制浓度分别为661.7 nmol/L及226.1 nmol/L,细胞克隆数也明显减少。qRT-PCR和Western印迹结果证明,与未经JIB-04处理的HCT116和HT29细胞比较,细胞周期蛋白D1(cyclinD1)、细胞周期蛋白E1(cyclinE1)的mRNA水平和CDK4、CDK6及细胞周期蛋白D1的蛋白质水平有不同程度的降低,同时CDK抑制剂p21的蛋白质水平分别上调约1.99倍和2.37倍。检测凋亡相关因子发现,在HCT116和HT29细胞中,p53、胱天蛋白酶3、胱天蛋白酶9、Bax、JNK及PUMA的mRNA及蛋白质水平均降低。机制研究显示,JIB-04使组蛋白赖氨酸特异性去甲基化酶1(LSD1)的mRNA水平分别下调约56.8%和75.5%,其蛋白质水平下调约27.12%和15.32%。本研究结果表明,JIB-04可改变组蛋白赖氨酸特异性去甲基化酶LSD1的活性,调控细胞周期蛋白及相关因子在mRNA和蛋白质水平的表达,同时诱导凋亡蛋白质发生改变,从而抑制结肠癌细胞增殖和凋亡。     

新的蒽醌类衍生物1-硝基-2-酰基蒽醌-苯丙氨酸通过抑制NF-κB/p65信号通路降低乳腺癌MCF-7细胞的迁移能力

肿瘤细胞的侵袭和转移与大多数癌症患者的死亡率密切相关。了解肿瘤细胞的迁移机制可为阻断肿瘤细胞的转移提供一个关键的策略。蒽醌衍生物具有一定的抗肿瘤作用,我们结合抗肿瘤药物的作用机制以及蒽醌类衍生物的构效关系,设计合成了一类新的酰胺蒽醌衍生物1-硝基-2-酰基蒽醌-苯丙氨酸(简称C7),发现其具有很好的抗肿瘤活性。为了探究蒽醌类衍生物C7对人乳腺癌MCF-7细胞迁移的作用及其机制,本文首先采用MTT比色法检测蒽醌类衍生物C7对人乳腺癌细胞MCF-7生长活力的影响,结果证明较高浓度(60~100μg/m L)的蒽醌类衍生物C7对乳腺癌MCF-7细胞的增殖具有明显的抑制作用。其次,采用细胞划痕实验检测C7对MCF-7细胞迁移的影响,发现较低浓度(20~40μg/m L)的蒽醌类衍生物C7可以显著降低MCF-7细胞的迁移率。为进一步探究C7抑制MCF-7细胞迁移的分子机制,通过免疫荧光技术检测NF-κB/p65蛋白的核转位情况;同时利用qRT-PCR及Western印迹实验检测C7对MCF-7细胞中NF-κB/p65通路及迁移相关基因和蛋白质表达的影响。结果表明C7可以下调细胞质中IκBα的磷酸化,降低NF-κB/p65蛋白的核转位,减小MMP-2和MMP-9蛋白的表达。因此,C7可能是通过抑制NF-κB/p65信号通路的活化,抑制MMP-2和MMP-9蛋白的表达,进而抑制MCF-7细胞的迁移。     

新的蒽醌类衍生物1-硝基-2-酰基蒽醌-苯丙氨酸通过抑制NF-κB/p65信号通路降低乳腺癌MCF-7细胞的迁移能力北大核心CSCD

肿瘤细胞的侵袭和转移与大多数癌症患者的死亡率密切相关。了解肿瘤细胞的迁移机制可为阻断肿瘤细胞的转移提供一个关键的策略。蒽醌衍生物具有一定的抗肿瘤作用,我们结合抗肿瘤药物的作用机制以及蒽醌类衍生物的构效关系,设计合成了一类新的酰胺蒽醌衍生物1-硝基-2-酰基蒽醌-苯丙氨酸(简称C7),发现其具有很好的抗肿瘤活性。为了探究蒽醌类衍生物C7对人乳腺癌MCF-7细胞迁移的作用及其机制,本文首先采用MTT比色法检测蒽醌类衍生物C7对人乳腺癌细胞MCF-7生长活力的影响,结果证明较高浓度(60~100μg/m L)的蒽醌类衍生物C7对乳腺癌MCF-7细胞的增殖具有明显的抑制作用。其次,采用细胞划痕实验检测C7对MCF-7细胞迁移的影响,发现较低浓度(20~40μg/m L)的蒽醌类衍生物C7可以显著降低MCF-7细胞的迁移率。为进一步探究C7抑制MCF-7细胞迁移的分子机制,通过免疫荧光技术检测NF-κB/p65蛋白的核转位情况;同时利用qRT-PCR及Western印迹实验检测C7对MCF-7细胞中NF-κB/p65通路及迁移相关基因和蛋白质表达的影响。结果表明C7可以下调细胞质中IκBα的磷酸化,降低NF-κB/p65蛋白的核转位,减小MMP-2和MMP-9蛋白的表达。因此,C7可能是通过抑制NF-κB/p65信号通路的活化,抑制MMP-2和MMP-9蛋白的表达,进而抑制MCF-7细胞的迁移。     

LncRNA RP1通过调控细胞周期蛋白质促进结肠癌细胞增殖

长链非编码RNAs(long non-coding RNAs, lncRNAs)是一类无蛋白质编码功能,长度大于200 nt的RNAs。qRT-PCR实验证实,lncRNA RP1-506.5(命名为RP1)在人结肠癌细胞株中的表达量明显高于人正常结肠上皮细胞。RP1在结肠癌组织中的表达量为癌旁组织表达量的8.5倍。在HCT116细胞中,上调RP1的表达,同时在HCT8细胞中沉默RP1的表达,探讨RP1对结肠癌细胞生物学特性的影响。MTS检验、活细胞工作站增殖实验,结合平板克隆检测发现,过表达RP1能明显促进结肠癌细胞HCT116的增殖能力。而在HCT8细胞中沉默RP1表达后,该细胞的增殖能力明显减弱。流式细胞周期分析的结果表明,RP1能促进细胞周期快速通过G_1/S检测点,并能加速S期进程。荧光定量PCR、Western印迹检测发现,在HCT116细胞中上调RP1的表达,P21的表达水平下调,细胞周期蛋白D1(cyclinD1)、依赖细胞周期蛋白激酶6(CDK6)表达水平上调;当沉默LncRNA RP1的表达时,能上调P21的表达水平,下调cyclinD1、CDK6的表达水平。上述结果表明,LncRNA RP1可通过调控周期相关蛋白质的表达促进结肠癌细胞增殖。     

ASPP2增强结肠癌HCT116细胞对奥沙利铂的化疗敏感性

为研究ASPP2对奥沙利铂诱导的结肠癌细胞系HCT116 p53+/+(野生型)凋亡及周期的影响.利用ASPP2（rAd-ASPP2）及p53腺病毒（rAd-p53）感染HCT116 p53+/+细胞,经奥沙利铂50 μmol/L诱导细胞凋亡及周期改变.Western印迹检测ASPP2及p53的表达水平;MTT法检测ASPP2腺病毒对奥沙利铂诱导的HCT116细胞活性的影响;Calcein/PI吸收试验检测细胞凋亡情况;流式细胞术分析细胞周期分布. 结果显示,ASPP2、p53共同过表达,或者ASPP2单独过表达均能增强奥沙利铂诱导的HCT116 p53+/+细胞增殖抑制,以及S期抑制并伴有细胞凋亡水平的升高;而无奥沙利铂诱导时,ASPP2对HCT116 p53+/+细胞的活性、细胞周期及细胞凋亡水平的影响无统计学意义. 上述结果表明,ASPP2能够增强奥沙利铂诱导HCT116 p53+/+细胞的增殖抑制、细胞周期抑制和细胞凋亡.     

LncRNA RP1调控周期蛋白质促进结肠癌细胞增殖

长链非编码RNAs（long non-coding RNAs, lncRNAs）是一类无蛋白质编码功能,长度大于 200 nt的RNAs。qRT-PCR实验证实,lncRNA RP1-506.5（命名为RP1）在人结肠癌细胞株中的表达量明显高于人正常结肠上皮细胞（P<0.01）。RP1在结肠癌组织中的表达量为癌旁组织中表达量的8.5倍。在HCT116中,上调RP1的表达,同时在HCT8中沉默RP1的表达,探讨RP1对结肠癌细胞生物学特性的影响。MTS实验、活细胞工作站增殖实验,结合平板克隆实验发现,过表达RP1能明显促进结肠癌细胞HCT116的增殖能力。而在HCT8细胞中沉默RP1表达后,该细胞的增殖能力明显减弱。流式细胞周期实验结果表明,RP1能促进细胞周期快速通过G1/S检测点,并能加速S期进程。荧光定量PCR、Western印迹实验发现,在HCT116中细胞中,上调RP1的表达后,P21的表达水平下调,细胞周期蛋白D1（cyclinD1）、依赖细胞周期蛋白激酶6(CDK6)表达水平上调;当沉默LncRNA RP1的表达后,能上调P21的表达水平,下调cyclinD1、CDK6的表达水平。这些结果表明,LncRNA RP1可通过调控周期相关蛋白质的表达促进结肠癌细胞增殖。     

BET抑制剂JQ1通过调控GSK3对结肠癌细胞HCT116增殖及凋亡的影响

摘要 目的：探讨BET抑制剂JQ1通过调控GSK3对结肠癌细胞HCT116增殖及凋亡的影响。方法：将HCT116细胞进行培养,按处理方式的不同分为对照组（NC组）、给药组（JQ1组）、给药+沉默组（JQ1+siRNA-GSK3组）与给药+过表达组（JQ1+OE-GSK3组）。分别通过细胞增殖-毒性检测（CCK-8）实验检测细胞增殖情况;原位末端标记（TUNEL）染色观察细胞凋亡水平;流式细胞术检测细胞凋亡数量;逆转录-聚合酶链反应（RT-PCR）检测相关mRNA含量水平表达变化;蛋白质印迹法（Western Blot）检测增殖与凋亡相关蛋白表达情况。结果：与NC组表现出的高增殖活性相比,给予JQ1后能够明显抑制HCT116细胞的增殖活性（P<0.05）;与JQ1组相比,沉默GSK3后其增殖活性则进一步下降,过表达GSK3后其增殖活性明显上升（P<0.05）。TUNEL染色结果显示,对NC组相比,JQ1组及JQ1+siRNA-GSK3组细胞凋亡水平显著上升;与JQ1组相比,过表达GSK3后其凋亡水平明显降低（P<0.05）。流式细胞术结果显示,NC组细胞凋亡数量最少,而给予JQ1后凋亡细胞数量显著增加,同时沉默GSK3后其细胞凋亡数量进一步上升,过表达GSK3后细胞凋亡数量明显下降（P<0.05）。Western Blot与RT-PCR显示;与NC组相比,给予JQ1及siRNA-GSK3处理后Caspase-3及BAX表达显著增加,GSK3与PCNA表达显著降低（P<0.05）;与JQ1组相比,过表达GSK3后Caspase-3及BAX表达明显降低,GSK3与PCNA表达明显上调（P<0.05）。结论：JQ1能够抑制HCT116细胞的增殖水平并促进其凋亡,从而发挥抗肿瘤作用,这一过程可能与JQ1能够抑制GSK3的表达有关。     

双(3-吗啉丙氧基)姜黄素抗肿瘤活性研究

合成双(3-吗啉丙氧基)姜黄素(PR1),研究PR1体内外抗肿瘤活性。姜黄素与N-(3-氯丙基)吗啉反应制备PR1,MTT法评价PR1体外对人肾癌细胞OS-RC-2、786-O和人慢性粒细胞白血病耐药细胞KA的抑制增殖活性,考察PR1体内抑制人结肠癌HT29裸鼠移植性肿瘤活性。PR1体外对肾癌细胞OS-RC-2和786-O抑制活性比姜黄素强,而对白血病耐药细胞KA抑制活性比姜黄素差。PR1体内对BALB/C-nu小鼠HT29皮下移植瘤的抑制作用明显,100 mg/kg·d灌胃的抑制率为55.7%,差别具有显著性(P0.01),对裸鼠的体重无明显影响。PR1在体内外均有较强抗肿瘤活性。     

核受体PXR对人结肠癌细胞增殖和化疗敏感性的影响

目的:探讨核受体PXR在结肠癌细胞增殖和化疗敏感性中的作用.方法:分别用RT-PCR和westernblot方法检测PXR在人结肠癌细胞株LS174T、LOVO、HT29、HCT116中的表达情况.通过质粒稳定转染方法建立PXR敲低的细胞株.用MTT方法分析利福平活化PXR或稳定转染敲低PXR后,细胞增殖和化疗敏感性的改变.结果:在结肠癌细胞株LS174T、LOVO、HT29、HCT116中,LS174T细胞的PXR表达水平最高.利福平处理后,LS174T细胞中PXR表达增强.利福平活化PXR或稳定转染敲低PXR后,相应地促进或抑制细胞增殖,降低或提高细胞对化疗药物的敏感性.结论:PXR能促进结肠癌细胞增殖,提高细胞对化疗药物的敏感性,可能在结肠癌多药耐药机制中具有重要作用.     

TET1 suppresses colon cancer proliferation by impairing β-catenin signal pathway

The function of ten-eleven translocation methylcytosine dioxygenase 1 (TET1) in cancer is background dependent and may be involved in the initial step of active DNA demethylation, while there is little research to decipher the role of TET1 in DNA methylation-sensitive colon cancer. Downregulated TET1 expression assayed by quantitative real-time PCR (qRT-PCR) was observed in both colon cancer samples and cancer cell lines of HT29, HCT116, and SW48. Such downregulation could promote colon cancer cells proliferation as indicated by the fact that shTET1 could increase the viability of HT29 and HCT116 cells determined by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide and cell count assay accompanied with upregulation of β-catenin (CTNNB1) and WNT luciferase activity, which was further confirmed as shTET1 could increase the tumor volume and tumor weight, and decrease the body weight in HT29 cells inoculated BALB/C nude mice. The CTNNB1 transfection could rescue the cell growth diminished by normal expression of TET1. shTET1 could promote axis inhibition protein1 (AXIN1) expression and the cell proliferation effect induced by TET1 short hairpin RNA was attenuated by co-inhibition of AXIN1. All of these indicate that TET1 can suppress colon cancer proliferation and the inhibition of the β-catenin pathway is AXIN1 dependent.     

Cox-2 is needed but not sufficient for apoptosis induced by Cox-2 selective inhibitors in colon cancer cells

The role of Cox-2 in NSAID-induced apoptosis is debated. We studied the role of Cox-2 inhibition in apoptosis induced by a selective Cox-2 inhibitor, SC236 (a structural analogue of celecoxib) in two colon cancer cell lines, HT29 (expressing Cox-2 protein) and HCT116 (not expressing Cox-2 protein). Apoptosis was quantified by flow cytometry. SC236 0–75 M decreased cell numbers and induced apoptosis to identical levels in HT29 and HCT116 cells. However, SC236, concentrations >75 M reduced Cox-2 protein expression in HT29 cells and induced greater levels of apoptosis in HT29 than in HCT116 cells. In contrast, sulindac sulfide (SSD) (which inhibits Cox-1 and Cox-2) 0–200 M or sulindac sulfone (SSN) 0–500 M (without significant activity against Cox-1 or Cox-2) caused identical decreases in cell number and increases in apoptosis in HT29 and HCT116 cells. Neither SSD nor SSN altered the expression of Cox-2 in HT29 cells. To determine that the higher levels of apoptosis in HT29 cells with SC236 >75 M were related to decreased Cox-2 protein levels, we decreased Cox-2 protein expression in HT29 cells with curcumin (diferuloylmethane) and studied its effect on SC236-induced apoptosis. Curcumin augmented apoptosis induced by SC236 in HT29 cells but not in Cox-2 lacking HCT116 cells. In conclusion, selective Cox-2 inhibitors can induce apoptosis independent of Cox-2 expression. However they may selectively target cells that express Cox-2 by decreasing their Cox-2 protein expression.     

UDP-Glucuronosyltransferase 1A Compromises Intracellular Accumulation and Anti-Cancer Effect of Tanshinone IIA in Human Colon Cancer Cells

Background and Purpose

NAD(P)H: quinone oxidoreductase 1 (NQO1) mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation is the dominant metabolic pathway of tanshinone IIA (TSA), a promising anti-cancer agent. UGTs are positively expressed in various tumor tissues and play an important role in the metabolic elimination of TSA. This study aims to explore the role of UGT1A in determining the intracellular accumulation and the resultant apoptotic effect of TSA.

Experimental Approach

We examined TSA intracellular accumulation and glucuronidation in HT29 (UGT1A positive) and HCT116 (UGT1A negative) human colon cancer cell lines. We also examined TSA-mediated reactive oxygen species (ROS) production, cytotoxicity and apoptotic effect in HT29 and HCT116 cells to investigate whether UGT1A levels are directly associated with TSA anti-cancer effect. UGT1A siRNA or propofol, a UGT1A9 competitive inhibitor, was used to inhibit UGT1A expression or UGT1A9 activity.

Key Results

Multiple UGT1A isoforms are positively expressed in HT29 but not in HCT116 cells. Cellular S9 fractions prepared from HT29 cells exhibit strong glucuronidation activity towards TSA, which can be inhibited by propofol or UGT1A siRNA interference. TSA intracellular accumulation in HT29 cells is much lower than that in HCT116 cells, which correlates with high expression levels of UGT1A in HT29 cells. Consistently, TSA induces less intracellular ROS, cytotoxicity, and apoptotic effect in HT29 cells than those in HCT116 cells. Pretreatment of HT29 cells with UGT1A siRNA or propofol can decrease TSA glucuronidation and simultaneously improve its intracellular accumulation, as well as enhance TSA anti-cancer effect.

Conclusions and Implications

UGT1A can compromise TSA cytotoxicity via reducing its intracellular exposure and switching the NQO1-triggered redox cycle to metabolic elimination. Our study may shed a light in understanding the cellular pharmacokinetic and molecular mechanism by which UGTs determine the chemotherapy effects of drugs that are UGTs’ substrates.     

PXR基因外显子3甲基化与肠癌细胞对5氟尿嘧啶的耐药性相关

孕烷X受体（pregnane X receptor, PXR）可通过调节细胞色素P450同工酶3A4 -CYP3A4的表达而影响肿瘤细胞对化疗的敏感性,而其表达水平则会受到自身基因 甲基化的影响.本文研究了结肠癌组织中pxr基因甲基化的分布情况及其对pxr, cyp3a4表达的影响,并在多种结肠癌细胞系中分析了pxr基因甲基化是否与5-氟尿嘧 啶 (5-FU)耐药性相关.收集结肠癌病灶区、癌旁区及正常结肠组织样本,分别提取基因组DNA及RNA.PCR限制性酶切分析检测pxr基因外显子3甲基化;real-time PCR检测pxr及cyp3a4基因的表达.鉴定LOVO、LS180、LS174T、HT29、HCT116等5种结 肠癌细胞中pxr外显子3甲基化与pxr, cyp3a4表达的相关性并分别筛选出PXR高/低表达的细胞株进行5-FU耐药性分析.结果显示,结肠癌病灶组织中pxr外显子3甲基化频率显著增加,伴有pxr,cyp3a4表达的增强.在结肠组织及结肠癌细胞系中,pxr与cyp3a4的表达均密切相关,且均与pxr甲基化程度相关.PXR高表达细胞株LS180对5-FU的耐药性显著升高,以siRNA分别下调pxr及cyp3a4的表达,均可增加LS180对5 -FU的敏感性.结果提示,pxr基因外显子3区甲基化与PXR及CYP3A4的高表达密切相关,并与结肠癌细胞对5-FU的抗药性相关.     

GPC1 exosome and its regulatory miRNAs are specific markers for the detection and target therapy of colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer‐related deaths worldwide. However, a biomarker for a sensitive and simple diagnostic test and highly effective target therapy of CRC is still clinically unavailable. This study is to investigate the evidence and significance of plasma GPC1 positive exosomes as a biomarker of CRC. Results showed that GPC1⁺ exosomes were successfully isolated from tissues and plasma. The percentage of GPC1⁺ exosomes and the GPC1 protein expression in exosomes from tumour tissues and plasma of CRC patients before surgical treatment was significantly elevated compared to that in the peritumoural tissues and the plasma of healthy controls. miR‐96‐5p and miR‐149 expression in tumour tissues and plasma of CRC patients as well as in the GPC1⁺ exosomes from CRC patients were significantly decreased compared to that in the peritumoural tissues and the plasma of healthy controls. Two months after surgical treatment, levels of all tested markers significantly normalized. Overexpression of miR‐96‐5p and miR‐149 significantly decreased GPC1 expression in HT‐29 and HCT‐116 cells, xenograft tumours, plasma in mice bearing HT‐29 and HCT‐116 tumours, and the secretion of GPC1⁺ exosomes from the HT‐29 and HCT‐116 cells and xenograft tumours. Overexpression of miR‐96‐5p and miR‐149 significantly decreased cell viability and increased cell apoptosis in HT‐29 and HCT‐116 cells, and inhibited the growth of xenograft HT‐29 and HCT‐116 tumours. In conclusion, the increased plasma GPC1⁺ exosomes and reduced plasma miR‐96‐5p and miR‐149 expression are specific markers for the diagnosis of CRC and targets for the therapy of CRC.     

Protein kinase CbetaII regulates its own expression in rat intestinal epithelial cells and the colonic epithelium in vivo

Protein kinase C betaII (PKCbetaII) is induced early during colon carcinogenesis. Transgenic mice expressing elevated PKCbetaII in the colonic epithelium (transgenic PKCbetaII mice) exhibit hyperproliferation and enhanced colon carcinogenesis. Here we demonstrate that nullizygous PKCbeta (PKCbetaKO) mice are highly resistant to azoxymethane (AOM)-induced preneoplastic lesions, aberrant crypt foci. However, reexpression of PKCbetaII in the colon of PKCbetaKO mice by transgenesis restores susceptibility to AOM-induced colon carcinogenesis. Expression of human PKCbetaII in rat intestinal epithelial (RIE) cells induces expression of endogenous rat PKCbetaII mRNA and protein. Induction of PKCbetaII is dependent upon catalytically active PKCbetaII and does not appear to involve changes in alternative splicing of the PKCbeta gene. Two human PKCbeta promoter constructs are activated by expression of PKCbetaII in RIE cells. Both PKCbeta promoter activity and PKCbetaII mRNA levels are inhibited by the MEK1 and -2 inhibitor U0126, but not the Cox-2 inhibitor celecoxib in RIE/PKCbetaII cells. PKCbeta promoter activity correlates directly with expression of endogenous PKCbetaII mRNA and protein in HT29 and HCT116 human colon cancer cell lines. PKCbeta promoter activity and PKCbetaII mRNA expression in HCT116 cells are inhibited by the selective PKCbeta inhibitor LY317615 and by U0126, demonstrating autoregulation of PKCbetaII expression. Transgenic PKCbetaII mice exhibit specific induction of endogenous PKCbetaII, but not its splice variant PKCbetaI, in the colonic epithelium in vivo. Taken together, our results demonstrate that 1) expression of PKCbetaII in the colonic epithelium is both necessary and sufficient to confer susceptibility to AOM-induced colon carcinogenesis in transgenic mice, 2) PKCbetaII regulates its own expression in RIE and human colon cancer cells in vitro and in the colonic epithelium in vivo, and 3) PKCbetaII autoregulation is mediated through a MEK-dependent signaling pathway in RIE/PKCbetaII and HCT116 colon cancer cells.     

Expression of Nucleophosmin/NPM1 correlates with migration and invasiveness of colon cancer cells

Background

We aimed to examine the expression level of Nucleophosmin (NPM1) protein in colon cancer tissues and to investigate the potential role of NPM1 in the regulation of cell migration and invasiveness.

Methods

Immunohistochemical assay was performed to examine the expression pattern of NPM1 in 31 groups of colonic carcinoma samples, including colon tumors, adjacent normal tissues, and matched metastatic lymph nodes from the same patients. Small interfering RNA technique and exogenous expression of wild type NPM1 methods were used to further verify the function of NPM1.

Results

High-expression of NPM1 correlates with lymph node metastasis (P = 0.0003) and poor survival rate of human colon cancer patients (P = 0.017). SiRNA-mediated reduction of NPM1 was also shown to inhibit the migration and invasiveness of metastatic colon cancer HCT116 cell line. In addition, the exogenous expression of NPM1 in HT29 cells, a NPM1 low expression and low invasive colon cancer cell line, enhanced cell migration and invasiveness along with increased cell proliferation.

Conclusions

The current study uncovered the critical role of NPM1 in the regulation of colon cancer cells migration and invasion, and NPM1 may serve as a potential marker for the prognosis of colon cancer patients.     

UDP-Glucuronosyltransferase 1A Determinates Intracellular Accumulation and Anti-Cancer Effect of β-Lapachone in Human Colon Cancer Cells

β-lapachone (β-lap), an NAD(P)H:quinone oxidoreductase 1 (NQO1) targeting antitumor drug candidate in phase II clinical trials, is metabolically eliminated via NQO1 mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation. This study intends to explore the inner link between the cellular glucuronidation and pharmacokinetics of β-lap and its apoptotic effect in human colon cancer cells. HT29 cells S9 fractions exhibited high glucuronidation activity towards β-lap, which can be inhibited by UGT1A9 competitive inhibitor propofol. UGT1A siRNA treated HT29 cells S9 fractions displayed an apparent low glucuronidation activity. Intracellular accumulation of β-lap in HCT116 cells was much higher than that in HT29 cells, correlated with the absence of UGT1A in HCT116 cells. The cytotoxic and apoptotic effect of β-lap in HT29 cells were much lower than that in HCT116 cells; moreover, β-lap triggered activation of SIRT1-FOXO1 apoptotic pathway was observed in HCT116 cells but not in HT29 cells. Pretreatment of HT29 cells with UGT1A siRNA or propofol significantly decreased β-lap’s cytotoxic and apoptotic effects, due to the repression of glucuronidation and the resultant intracellular accumulation. In conclusion, UGT1A is an important determinant, via switching NQO1-triggered redox cycle to metabolic elimination, in the intracellular accumulation of β-lap and thereafter its cytotoxicity in human colon cancer cells. Together with our previous works, we propose that UGTs determined cellular pharmacokinetics is an important determinant in the apoptotic effects of NQO1 targeting substrates serving as chemotherapeutic drugs.     

MicroRNA-218 Inhibits Cell Cycle Progression and Promotes Apoptosis in Colon Cancer by Downregulating BMI1 Polycomb Ring Finger Oncogene

Deregulated miRNAs participate in colorectal carcinogenesis. In this study, miR-218 was found to be downregulated in human colorectal cancer (CRC) by miRNA profile assay. miR-218 was silenced or downregulated in all five colon cancer cells (Caco2, HT29, SW620, HCT116 and LoVo) relative to normal colon tissues. miR-218 expression was significantly lower in 46 CRC tumor tissues compared with their adjacent normal tissues (P < 0.001). Potential target genes of miR-218 were predicted and BMI1 polycomb ring finger oncogene (BMI-1), a polycomb ring finger oncogene, was identified as one of the potential targets. Upregulation of BMI-1 was detected in CRC tumors compared with adjacent normal tissues (P < 0.001) and in all five colon cancer cell lines. Transfection of miR-218 in colon cancer cell lines (HCT116, HT29) significantly reduced luciferase activity of the wild-type construct of BMI-1 3′ untranslated region (3′UTR) (P < 0.001), whereas this effect was not seen in the construct with mutant BMI-1 3′UTR, indicating a direct and specific interaction of miR-218 with BMI-1. Ectopic expression of miR-218 in HCT116 and HT29 cells suppressed BMI-1 mRNA and protein expression. In addition, miR-218 suppressed protein expression of BMI-1 downstream targets of cyclin-dependent kinase 4, a cell cycle regulator, while upregulating protein expression of p53. We further revealed that miR-218 induced apoptosis (P < 0.01), inhibited cell proliferation (P < 0.05) and promoted cell cycle arrest in the G2 phase (P < 0.01). In conclusion, miR-218 plays a pivotal role in CRC development through inhibiting cell proliferation and cycle progression and promoting apoptosis by downregulating BMI-1.