和厚朴酚及厚朴酚抗结直肠癌和胃癌药理作用及其机制的研究进展

和厚朴酚及厚朴酚是疏水性联苯酚类结构的同分异构体。和厚朴酚能防治结直肠癌CT26细胞或RKO细胞移植瘤在小鼠体内生长,并延长荷瘤小鼠的生存时间。体外实验发现和厚朴酚及厚朴酚能浓度相关地抑制结直肠癌SW480细胞、SW620细胞、LoVo细胞、LS180细胞、CT26细胞、RKO细胞、Caco-2细胞、COLO-205细胞、HCT-8细胞、HCT15细胞、HCT116细胞增殖,并诱导细胞凋亡。在HCT116细胞中,hMLH1错配修复缺失型细胞对和厚朴酚的敏感性高于完整型细胞。和厚朴酚是通过调控JNK/Nur77/AMPK、TGF-β1/p38MAPK/Hippo、BMP7/TGF-β1/p53和BMP7/PTEN/AKT 4条信号转导通路诱导结直肠癌细胞凋亡,还通过抑制血管内皮生长因子的表达,阻滞肿瘤内新生血管形成,抑制结直肠癌生长。和厚朴酚及厚朴酚还能抑制胃癌MGC-803细胞和SGC-7901细胞的增殖。     

5-氟脲嘧啶诱导人结直肠癌Lovo细胞凋亡的分子机制

目的：研究5-氟脲嘧啶（5-FTU）对体外培养人结直肠癌Lovo细胞增殖的抑制作用及诱导凋亡的分子机制。方法：分别采用MTT法检测细胞活力．用光镜、电镜观察凋亡细胞的组织形态学和超微结构变化，流式细胞术（FCM）分析诱导细胞凋亡的细胞周期阻滞点，免疫组化SP法检测对Lovo细胞增殖核抗原（PCNA）及凋亡相关基因蛋白P53、Bax表达的影响。结果：5-FU能抑制Lovo细胞生长，光镜与电镜结果均显示凋亡细胞明显增多。FCM分析Lovo细胞经5-FU诱导后凋亡百分率显著增加，并具有剂量和时间的效应。免疫组化显示5-FU组细胞PCNA表达明显低于对照组、Bax表达明显升高（P〈0．01），而P53在诱导前后均无表达。结论：5-FU能抑制Lovo细胞增殖并通过诱导该细胞系凋亡发挥抗肿瘤效应，激活bax基因和G2／M期阻滞是其诱导Lovo细胞凋亡的重要机制。     

反义DLC-1基因对结直肠癌LoVo细胞增殖和细胞周期的影响

目的 应用核糖核酸干扰(RNAi)技术,通过对大肠癌细胞株LoVo中DLC-1基因mRNA表达的抑制,初步探讨DLC-1基因对大肠癌细胞株的生物学行为影响.方法 构建DCL-1的RNAi重组体pGCsiDLC,转染大肠癌LoVo细胞株.采用RT-PCR观察转染前后细胞株中DLC-1 mRNA以及 Bax、Bcl-2基因表达的改变,MTT比色法检测转染前后细胞增殖,流式细胞仪检测细胞周期.结果 成功构建发卡siRNA真核表达载体pGCsiDLC;pGCsiDLC转染LoVo细胞后,电泳显示DLC-1 mRNA表达水平明显下降;LoVo细胞生长曲线增长幅度亦随时间的增加而逐渐增高,在48h最为明显,RNAi组细胞比脂质体组及空白对照组细胞增殖明显增高(P＜0.05);干扰后的LoVo细胞株G0/G1期发生阻滞,而G2/M 期细胞数量分布减少.而Bax和bcl-2基因表达在干扰前后未见明显改变.结论 成功构建载体介导的DLC-1靶向RNAi重组体可有效抑制LoVo细胞DLC-1 mRNA表达;DLC-1基因可抑制结直肠癌细胞增殖并且对细胞周期重新分布,其可能与结直肠癌的发生发展有一定关系,可能是一个新的抑癌基因.     

Reg Ⅳ基因对5-FU干预结直肠癌LoVo细胞增殖、凋亡的影响

目的 观察Reg Ⅳ基因对5-FU干预结直肠癌LoVo细胞增殖、凋亡的影响.方法 构建重组质粒pcDNA3.1-RegⅣ并转染LoVo细胞,RT-PCR和细胞免疫组化检测转染前后细胞中Reg Ⅳ基因的mRNA和蛋白表达.终浓度80 μmol/L的5-FU干预细胞48 h后,MTT检测细胞的增殖活性.平板克隆实验观察细胞的克隆形成能力.FCM检测细胞凋亡.结果 LoVo细胞不表达Reg Ⅳ基因,转染后的LoVo/RegⅣ细胞高表达RegⅣ.5-FU干预后,未转染组(LoVo)和空转质粒组(LoVo/空载)细胞增殖活性、克隆形成能力较RegⅣ转染组(LoVo/RegⅣ)明显降低(P<0.05),细胞凋亡率较RegⅣ转染组明显升高(P<0.05).结论 RegⅣ基因表达可能降低5-FU抑制LoVo细胞的增殖活性及克隆形成能力,并能抑制5-FU诱导LoVo细胞凋亡的作用.Reg Ⅳ基因可能是患者对5-FU化疗产生抗药性的标志及导致临床化疗失败的原因之一.     

半边旗提取物5F诱发结直肠癌细胞生长抑制及细胞凋亡

目的：检测半边旗（PsL）提取物5F（ent -11α- hydroxy -15- oxo - kaur -16- en -19- oic - acid）对HCT -116结直肠癌（CRC）细胞的抗增殖及促细胞凋亡效果。方法采用噻唑蓝（MTT）法检测细胞毒性。通过有代表性的细胞凋亡相关蛋白表达及 Annexin V/ PI 染色确定细胞凋亡。采用标准实验方案测量活性氧（ROS）水平。结果5F 以剂量依赖及时间依赖方式抑制 HCT -116细胞增殖。免疫印迹分析表明5F 提高了 HCT -116细胞中的 Bax/ Bcl -2比值。5F 能既够增强顺铂（cisplatin）对 HCT -116细胞生长的抑制效果又能够提高顺铂诱导的 HCT-116细胞凋亡水平。5F 不仅没有提高活性氧水平,反而降低了顺铂诱导的活性氧生成。结论5F 能够诱导结直肠癌细胞凋亡并因此表现出癌症治疗潜力。     

基于PI3K/Akt/mTOR信号通路探讨黄芪多糖对结直肠癌自噬的影响

目的 探讨黄芪多糖（APS）对结直肠癌自噬的影响及其机制。方法 采用CCK-8法检测APS各剂量（0.25 g/L、0.5 g/L、0.75 g/L、1 g/L）组对人结直肠癌HCT-116细胞增殖的影响，通过细胞划痕实验检测APS对HCT-116细胞迁移的影响，通过单丹磺酰尸胺染色检测APS对结直肠癌细胞自噬的影响，采用Western blot法检测APS对HCT-116细胞和结直肠癌荷瘤裸鼠肿瘤中自噬及PI3K/Akt/mTOR信号通路相关蛋白LC3B、p62、p-PI3K、p-Akt、p-mTOR、PI3K、Akt及m TOR表达的影响；通过免疫组化染色检测APS对结直肠癌肿瘤中自噬相关蛋白p62表达的影响。结果APS可抑制HCT-116细胞增殖，且呈剂量依赖性（P<0.05）;APS可通过诱导细胞自噬抑制HCT-116细胞增殖和迁移，而自噬抑制剂3-MA(2 mmol/L)不仅可减弱APS对HCT-116细胞自噬的诱导作用，也可减弱APS对HCT-116细胞增殖和迁移的抑制作用（P<0.05）;APS可上调HCT-116细胞及结直肠癌小鼠肿瘤中自噬相关蛋白LC3BⅡ...     

大黄蛰虫丸对AOM/DSS诱导结肠炎相关 结直肠癌小鼠的抑制作用

摘 要 目的：研究大黄蛰虫丸（DZP）对结肠炎相关结直肠癌（CAC）的影响及其可能机制。方法：以C57BL/6小鼠为研究对象,随机分为对照组、模型组,DZP低（2 g·kg-1）、高剂量组（4 g·kg-1）。除对照组外,其余各组采用AOM/DSS诱导小鼠CAC模型,并于造模中各组给予相应的药物灌胃干预。实验结束,比较各组小鼠死亡率,并以ELISA检测小鼠血清IL-1β和IL-18水平;苏木素-伊红（HE）染色观察结肠组织损伤情况;免疫荧光染色分析小鼠结肠Occludin和ZO-1的表达;免疫组化染色分析小鼠结肠ATG5、IL-1β和IL-18的表达水平;蛋白印迹检测小鼠结肠中LC3BⅠ/Ⅱ、SQSTM1及ATG5的蛋白表达水平。结果：经8周灌胃给药,对照组、模型组,DZP低、高剂量组的死亡率分别为0%、40.00%、20.00%、6.67%。与模型组相比,DZP能显著降低血清IL-1β和IL-18水平,提高小鼠肠道组织中Occludin和ZO-1的表达水平。同时,DZP能显著降低模型小鼠结肠组织中IL-1β、IL-18及SQSTM1的表达水平,提高模型小鼠肠道组织中的LC3BⅠ/Ⅱ和ATG5的蛋白表达水平。结论：DZP能显著降低CAC模型小鼠的炎症和死亡率;其作用机制可能与促进CAC模型小鼠肠道自噬改善肠道紧密连接相关。     

IL-22BP对肠炎相关性结直肠癌小鼠脾单核细胞和结肠组织炎症因子表达的影响

目的 探讨IL-22BP对肠炎相关性结直肠癌（colitis-associated colorectal cancer, CAC）小鼠脾单核细胞和结肠组织炎症因子表达的影响。方法 建立AOM/DSS诱导的CAC小鼠模型,观察给予IL-22BP后小鼠成瘤情况、结肠病理学改变、脾脏和结肠脏器指数,检测脾脏和结肠组织炎症因子IFN-γ、IL-17A、IL-22、IL-6和TNF-α的变化。结果 与模型组相比,IL-22BP组小鼠肿瘤数量明显减少,病理检测显示肿瘤评分和HAI评分均显著降低,脾脏指数和结肠指数显著下降,脾单核细胞和结肠组织 IFN-γ、IL-6和TNF-α水平增高,IL-17A水平降低,IL-22水平无明显改变。结论 IL-22BP可以调节CAC小鼠脾脏和结肠组织炎症因子IFN-γ、IL-17A、IL-6和TNF-α的水平。     

结直肠癌中Kiss-1基因启动子甲基化与Kiss-1基因表达的关系

目的：研究结直肠癌中Kiss-1基因启动子甲基化状态对Kiss-1基因表达的影响。方法：应用甲基化特异性PCR （MSP）方法检测73例结直肠癌、正常结直肠组织和人结直肠癌细胞HCT116、SW480、W1116、LoVo中Kiss-1基因启动子甲基化状态,应用realtime-PCR、Western-blot技术检测相应组织和细胞中Kiss-1基因mRNA和蛋白质（Metastine）的表达量。结果：结直肠癌中Kiss-1基因甲基化阳性率（82.19%）高于正常组织（6.31%）（PSW480〉SW1116〉HCT116,差异有统计学意义（p〈0.05）。结论：结直肠癌中Kiss-1基因启动子甲基化可能引起Kiss-1基因表达下调。     

辛伐他汀抑制过表达HER2型结直肠癌的肿瘤血管生成

目的探讨辛伐他汀在结直肠癌(CRC)血管生成调控中的作用及分子机制。方法 Western blot法检测HER2和VEGF蛋白表达。采用Matrigel小管形成、MTT、伤口愈合试验和Transwell检测辛伐他汀对CRC小管形成、增殖、迁移和侵袭能力的影响。另外,采用HTC-116和LoVo细胞构建裸鼠移植瘤模型,模型小鼠分成2组,对照组每日注射0.1 ml磷酸盐缓冲盐水,治疗组小鼠每天注射50 mg/kg辛伐他汀。免疫组化方法检测肿瘤CD31表达情况,计算肿瘤微血管密度(MVD)。观察辛伐他汀对裸鼠肿瘤生长及肿瘤血管形成的影响。结果 VEGF和HER2在CRC细胞中表达上调,而辛伐他汀明显降低其表达。辛伐他汀预处理可减少体外内皮细胞小管形成和体内微血管密度。辛伐他汀明显抑制HRG-β1诱导的血管形成。机制研究显示,辛伐他汀通过抑制VEGF分泌而显著抑制HER2诱导引起的肿瘤血管生成。结论辛伐他汀通过对HER2/VEGF轴的调控抑制肿瘤血管生成,为辛伐他汀抑制过表达HER2型CRC提供了一种新的机制。     

5’-氮杂-2’-脱氧胞苷对结直肠癌细胞株HT-29和LoVo中MGMT基因甲基化状态、mRNA表达及蛋白表达的影响

目的探讨甲基化酶抑制剂5’-氮杂-2’-脱氧胞苷（5’-Aza-CdR）对结直肠癌（colorectal cancer,CRC）细胞株HT-29和LoVo中MGMT基因甲基化水平、mRNA及蛋白表达的影响。方法用0.5、1.0、1.5μmol/L浓度的5’-Aza-CdR处理CRC细胞株HT-29和LoVo。应用MethyLight方法、实时荧光定量PCR方法及蛋白印迹试验（Westernblot）检测药物处理前后HT-29和LoVo细胞中MGMT基因的甲基化状态、mRNA和蛋白表达情况。结果 MethyLight检测HT-29和LoVo细胞中MGMT蛋白在药物作用后异常甲基化得到逆转。实时荧光定量PCR检测5’-Aza-CdR浓度为0.5、1.0、1.5μmol/L组HT-29细胞株和LoVo细胞株MGMT基因mRNA表达水平均较对照组上调,Western blot检测5’-Aza-CdR浓度为0.5、1.0、1.5μmol/L组MGMT蛋白表达水平均较对照组上调,且均具有药物剂量依赖性（P〈0.05,P〈0.01）。结论 CRC细胞株HT-29和LoVo中MGMT基因启动子甲基化可能是导致该基因表达下调甚至失活的主要原因。5’-Aza-CdR能够逆转CRC细胞株HT-29和LoVo中MGMT基因的甲基化状态,并能恢复mRNA及蛋白重新表达。     

Isoliquiritigenin,a flavonoid from licorice,blocks M2 macrophage polarization in colitis-associated tumorigenesis through downregulating PGE2 and IL-6

M2 macrophage polarization is implicated in colorectal cancer development. Isoliquiritigenin (ISL), a flavonoid from licorice, has been reported to prevent azoxymethane (AOM) induced colon carcinogenesis in animal models. Here, in a mouse model of colitis-associated tumorigenesis induced by AOM/dextran sodium sulfate (DSS), we investigated the chemopreventive effects of ISL and its mechanisms of action. Mice were treated with AOM/DSS and randomized to receive either vehicle or ISL (3, 15 and 75 mg/kg). Tumor load, histology, immunohistochemistry, and gene and protein expressions were determined. Intragastric administration of ISL for 12 weeks significantly decreased colon cancer incidence, multiplicity and tumor size by 60%, 55.4% and 42.6%, respectively. Moreover, ISL inhibited M2 macrophage polarization. Such changes were accompanied by downregulation of PGE₂ and IL-6 signaling. Importantly, depletion of macrophages by clodronate (Clod) or zoledronic acid (ZA) reversed the effects of ISL. In parallel, in vitro studies also demonstrated that ISL limited the M2 polarization of RAW264.7 cells and mouse peritoneal macrophages with concomitant inactivation of PGE₂/PPARδ and IL-6/STAT3 signaling. Conversely, exogenous addition of PGE₂ or IL-6, or overexpression of constitutively active STAT3 reversed ISL-mediated inhibition of M2 macrophage polarization. In summary, dietary flavonoid ISL effectively inhibits colitis-associated tumorigenesis through hampering M2 macrophage polarization mediated by the interplay between PGE₂ and IL-6. Thus, inhibition of M2 macrophage polarization is likely to represent a promising strategy for chemoprevention of colorectal cancer.     

Dextran sulfate sodium-induced colitis-associated neoplasia： a promising model for the development of chemopreventive interventions

Individuals diagnosed with ulcerative colitis face a significantly increased risk of developing colorectal dysplasia and cancer during their lifetime. To date, little attention has been given to the development of a chemopreventive intervention for this high-risk population. The mouse model of dextran sulfate sodium （DSS） - induced colitis represents an excellent preclinical system in which to both charac- terize the molecular events required for tumor formation in the presence of inflam- mation and assess the ability of select agents to inhibit this process. Cyclic admin- istration of DSS in drinking water results in the establishment of chronic colitis and the development of colorectal dysplasias and cancers with pathological fea- tures that resemble those of human colitis-associated neoplasia. The incidence and multiplicity of lesions observed varies depending on the mouse strain used （ie, Swiss Webster, C57BL/6J, CBA, ICR） and the dose （0.7%-5.0%） and schedule （1-15 cycles with or without a subsequent recovery period） of DSS. The incidence of neoplasia can be increased and its progression to invasive cancer accelerated significantly by administering DSS in combination with a known colon carcinogen （azoxymethane （AOM）, 2-amino-3-methylimidazo[4,5-f]quinoline （IQ）, 2-amino-1- methyl-6-phenylimidazo[4,5-b]pyridine （PhIP）） or iron. More recent induction of colitis-associated neoplasia in genetically defined mouse strains has provided new insight into the role of specific genes （ie, adenomatous polyposis coli （Apc）, p53, inducible nitric oxide synthase （iNOS）, Msh2） in the development of colitis- associated neoplasias. Emerging data from chemopreventive intervention studies document the efficacy of several agents in inhibiting DSS-induced neoplasia and provide great promise that colitis-associated colorectal neoplasia is a preventable disease.     

罗格列酮对实验性大鼠结肠癌的化学预防作用

目的:观察罗格列酮对实验性结肠癌的化学预防作用及其与环氧化酶-2(COX-2)表达的关系。方法:以二甲肼(1-2 dimethylhydrazine,DMH)40mg/kg皮下注射+1%葡聚糖硫酸钠(dextran sodium sulfate,DSS)水溶液饮用诱导形成大鼠结肠癌模型,观察罗格列酮(0.75mg.kg-1.d-1,1周5d)和美洛昔康(1.35mg.kg-1.d-1,1周5d)灌服、连续16周对大鼠体重、异常隐窝灶(ACF)和结肠癌发生率的影响。采用四甲基谷氮蓝法(MTT)研究罗格列酮和美洛昔康抑制培养的人结肠癌Lovo细胞增殖的量-效和时-效关系;用Western Blot法检测罗格列酮组细胞COX-2蛋白表达水平。结果:与模型组相比,罗格列酮明显改善DMH+DSS诱癌过程中大鼠的恶液质状态并阻遏体重减轻,显著减少实验第10周大鼠结肠ACF数和明显降低结肠癌的发生率;其作用与美洛昔康组相似。罗格列酮呈浓度和时间依赖性明显抑制Lovo细胞增殖,其作用6h、12h和24h的IC50均显著小于美洛昔康。罗格列酮呈浓度依赖性降低Lo-vo细胞中COX-2蛋白表达。结论:罗格列酮能抑制DMH和DSS联合使用诱导大鼠早期ACF的形成和结肠癌发生,其作用途径可能与抑制COX-2表达有关。     

槲皮素对结直肠癌细胞SW480增殖与Bcl-2、C-myc表达的影响

目的:研究槲皮素对结直肠癌细胞SW480增殖与B细胞淋巴瘤/白血病-2(Bcl-2)、癌基因C-myc表达的影响。方法:5、10、20、40、80、160μmol/L槲皮素处理SW480细胞后,采用MTT法检测SW480细胞增殖情况,计算细胞增殖抑制率;实时荧光定量反相聚合酶链反应(qRT-PCR)和Western blot法检测Bcl-2、C-myc mRNA和蛋白表达水平。结果:槲皮素对SW480细胞有明显抑制作用,能够诱导SW480细胞凋亡,且与剂量、时间呈正相关;40μmol/L槲皮素可明显抑制Bcl-2、C-myc mRNA的表达;处理48、72 h时40μmol/L槲皮素明显抑制Bcl-2、C-myc蛋白的表达(P<0.05)。结论:槲皮素能够抑制SW480细胞增殖,且呈时间-剂量依赖性,槲皮素可能通过下调Bcl-2、C-myc的表达水平而发挥抗结直肠癌作用。     

2,3��,4,4��,5��-Pentamethoxy-trans-stilbene, a resveratrol derivative, inhibits colitis-associated colorectal carcinogenesis in mice

Background and purpose:

Resveratrol, a naturally occurring polyphenolic antioxidant, has been shown to exhibit chemoprophylactic effects on cancer development. Previously, we reported that 2,3′,4,4′,5′-pentamethoxy-trans-stilbene (PMS), a methoxylated resveratrol derivative, exerted a highly potent anti-proliferative effect on human colon cancer cells as compared with its parent compound. In the present study, the chemopreventive effect of PMS was evaluated in a mouse model of colitis-associated colon carcinogenesis.

Experimental approach:

Seven-week-old Balb/c mice were injected i.p. with 10 mg·kg⁻¹ azoxymethane (AOM). After 1 week, 3% dextran sodium sulphate (DSS) was administered in the drinking water for 7 days followed by 14 days of tap water for recovery, and this cycle was repeated twice.

Key results:

Intragastric administration of PMS (25, 50 mg·kg⁻¹ body weight) for 16 weeks significantly reduced the multiplicity of colonic neoplasms by 15% and 35% (P < 0.01) respectively. Moreover, PMS at 50 mg·kg⁻¹ inhibited colon cancer cell proliferation and promoted apoptosis. Such changes were accompanied by reduction of Akt (protein kinase B) phosphorylation, inactivation of β-catenin and down-regulation of inducible nitric oxide synthase. In parallel, in vitro studies also demonstrated that PMS inhibited proliferation and induced apoptosis in the murine colon adenocarcinoma cell line Colon26 with concomitant inhibition of Akt phosphorylation and inactivation of β-catenin.

Conclusions and implications:

PMS effectively suppressed colon carcinogenesis in an AOM/DSS animal model and may merit further clinical investigation as a chemoprophylactic agent against colitis-associated colon cancer in humans.     

基于胆汁酸稳态调控的维生素D对结直肠癌的抑制作用及机制研究

目的考察维生素D(vitamin D,VD)是否可以通过调控胆汁酸内稳态,进而抑制AOM+DSS诱导的小鼠结直肠癌(colorectal cancer,CRC)的发生发展,并探讨其可能机制。方法将小鼠随机分为Control组、CRC组、CRC+VD组,采用AOM+DSS诱导建立CRC小鼠模型。HE染色检测组织病理情况;LC-MS/MS检测血清和结肠中各类型的胆汁酸含量;qPCR检测FXR、CYP7A1 mRNA的表达。结果CRC组小鼠结肠组织呈浸润性生长、病理性核分裂像可见;与CRC组相比,CRC+VD组小鼠结直肠长度增加,HE染色显示结肠各层结构相对清晰。CRC组小鼠血清中11种胆汁酸含量降低,而结肠组织中疏水性胆汁酸含量明显升高;而CRC+VD组T-LCA,LCA,T-CA,T-DCA,T-HDCA水平升高,结肠部位疏水性胆汁酸水平趋于正常。CRC组FXR、CYP7A1mRNA表达明显升高,而CRC+VD组CYP7A1 mR-NA表达较CRC组降低。结论CRC小鼠体内胆汁酸内稳态失衡,维生素D可调控CRC状态下循环及结肠部位胆汁酸稳态水平,调节疏水性胆汁酸比例,进而影响CRC的发生发展。     

5′-氮杂-2′-脱氧胞苷对 HT-29和 LoVo结直肠癌细胞株中 p16基因甲基化状态、mRNA表达及蛋白表达的影响

目的：探讨甲基化酶抑制剂5′-氮杂-2′-脱氧胞苷（5′-Aza-2′-deoxycytidine,5′-Aza-CdR）对结直肠癌细胞株HT-29和Lo-Vo中p16基因甲基化状态、mRNA及蛋白表达的影响。方法应用TaqMan探针为基础的实时定量PCR法、SYBR Green PCR法及蛋白印迹实验（ Western blot ）检测不同浓度5′-Aza-CdR处理前后HT-29和LoVo细胞中p16基因的甲基化状态、mRNA和蛋白表达。结果 TaqMan 探针为基础的实时定量PCR法检测HT-29和LoVo细胞中p16蛋白在药物作用后异常甲基化得到逆转;实时荧光定量PCR和Western Blot检测到0．5、1．0、1．5μM 5′-Aza-CdR处理后p16基因mRNA和蛋白均重新表达,具有统计学意义（P均＜0．05）。结论结直肠癌细胞株HT-29和LoVo中p16启动子甲基化可能是导致该基因表达下调甚至失活的主要原因。5′-Aza-CdR能够较成功的逆转结直肠癌细胞株HT-29和LoVo中p16基因的甲基化状态,并能恢复mRNA及蛋白重新表达。     

Arsenic and chromium in drinking water promote tumorigenesis in a mouse colitis-associated colorectal cancer model and the potential mechanism is ROS-mediated Wnt/β-catenin signaling pathway

Exposure to carcinogenic metals, such as trivalent arsenic [As(III)] and hexavalent chromium [Cr(VI)], through drinking water is a major global public health problem and is associated with various cancers. However, the mechanism of their carcinogenicity remains unclear. In this study, we used azoxymethane/dextran sodium sulfate (AOM/DSS)-induced mouse colitis-associated colorectal cancer model to investigate their tumorigenesis. Our results demonstrate that exposure to As(III) or Cr(VI), alone or in combination, together with AOM/DSS pretreatment has a promotion effect, increasing the colorectal tumor incidence, multiplicity, size, and grade, as well as cell inflammatory response. Two-dimensional differential gel electrophoresis coupled with mass spectrometry revealed that As(III) or Cr(VI) treatment alone significantly changed the density of proteins. The expression of β-catenin and phospho-GSK was increased by treatment of carcinogenic metals alone. Concomitantly, the expression of NADPH oxidase1 (NOX1) and the level of 8-OHdG were also increased by treatment of carcinogenic metals alone. Antioxidant enzymes, such as superoxide dismutase (SOD) and catalase, were decreased. Similarly, in an in vitro system, exposure of CRL-1807 to carcinogenic metals increased reactive oxygen species (ROS) generation, the expression of β-catenin, phospho-GSK, and NOX1. Inhibition of ROS generation by addition of SOD or catalase inhibited β-catenin expression and activity. Our study provides a new animal model to study the carcinogenicity of As(III) and Cr(VI) and suggests that As(III) and Cr(VI) promote colorectal cancer tumorigenesis, at least partly, through ROS-mediated Wnt/β-catenin signaling pathway.