具核梭杆菌通过调节肠道代谢产物丁酸钠上调Cdk1促进结直肠癌发展

该文探讨了肠道微生物具核梭杆菌(Fusobacterium nucleatum,Fn)通过调节代谢产物丁酸钠(NaB)对结直肠癌(CRC)发生发展的影响及其分子机制.提取临床组织RNA和蛋白,RT-qPCR和Western blot检测肿瘤组织与正常/癌旁组织Cdk1的mRNA及蛋白表达,同时检测具核梭杆菌的mRNA的...     

具核梭杆菌与结直肠癌关系的研究进展

结直肠癌(Colorectal cancer,CRC)是世界第三大癌症,涉及因素众多,而肠道菌群失调、菌群致病性与结直肠癌的发生、发展有着密不可分的关系。近期的研究发现具核梭杆菌(Fusobacterium nucleatum,F.nucleatum)与结直肠癌的发生存在显著的相关性。具核梭杆菌为革兰阴性厌氧菌,广泛存在于人体肠道中。分子机制研究发现,其能影响宿主细胞因子水平,促进血管生成、巨噬细胞M2极化和抑制机体免疫调节能力,进而增强肿瘤细胞增殖、侵袭及转移。本文就具核梭杆菌与结直肠癌相关机制研究进展作一综述。     

具核梭杆菌促进结直肠癌发生发展机制的研究进展

结直肠癌（colorectal cancer,CRC）是一种全球高发的恶性肿瘤,肠道菌群失调作为潜在致病因素逐渐受到关注。大量的研究发现具核梭杆菌（Fusobacterium nucleatum,F. nucleatum）在CRC组织中丰度显著升高,与CRC的发生有关,目前其具体的作用机制尚不明确。分子及细胞学研究表明F. nucleatum能够破坏肠道上皮屏障、损伤细胞DNA、影响肿瘤相关microRNAs的表达和促进肿瘤细胞转移。本文就F. nucleatum促进CRC发生发展的机制及相关研究进展作一综述。

     

具核梭杆菌对结直肠癌诊疗作用的研究进展

口腔菌群作为人体的第二大微生物群,对人体健康具有非常重要的作用。具核梭杆菌是口腔中的常驻菌之一,与其他菌共同维持机体的稳态,现已被证实是结直肠癌最相关的菌属之一,参与结直肠癌的发生、发展以及预后。很多学者根据具核梭杆菌在结直肠癌中的致病机制,寻找以具核梭杆菌为靶点的对结直肠癌进行早期诊断和治疗的新方法。本文阐述了具核梭杆菌在结直肠癌中的致病机制,着重探讨其在结直肠癌的诊断和治疗中的潜在作用,以期为临床诊疗提供参考。

     

纳米材料治疗具核梭杆菌促进的结直肠癌研究进展

具核梭杆菌(Fusobacterium nucleatum,Fn)是一种口腔厌氧菌,最近被发现在人类结直肠癌(colorectal cancer,CRC)细胞表面聚集,其富集程度与癌症治疗预后呈高度负相关。大量研究表明,Fn参与CRC的发生与发展过程,Fn与肿瘤微环境中多种组分相互作用从而增强肿瘤的耐药性。近年来,开始有研究利用纳米材料抑制Fn在肿瘤部位的增殖或通过直接靶向Fn治疗CRC。因此,本综述一方面将对近年来Fn在CRC中促肿瘤的机制进行梳理总结,另一方面将归纳整理不同纳米材料应用于Fn相关CRC治疗的最新研究进展,最后对纳米材料在Fn介导的CRC治疗中的应用前景进行了展望。     

具核梭杆菌促进结直肠癌发生发展机制研究进展

具核梭杆菌(Fusobacterium nucleatum)是一种人体共生菌,尤其富集于口腔,在特定情况下可导致机会感染.近年来,随着微生物群与健康或疾病相关性研究的深入,具核梭杆菌与结直肠癌(colorectal cancer,CRC)之间的关联性研究备受关注.大量临床研究表明,具核梭杆菌在CRC中更为富集,且进一步...     

具核梭杆菌对结直肠癌小鼠化疗敏感性的影响

目的研究具核梭杆菌对结直肠癌小鼠化疗敏感性的影响。方法建立结直肠癌荷瘤小鼠,分为空白对照组、5-氟尿嘧啶对照组和实验组、奥沙利铂实验组和对照组、伊立替康实验组和对照组、阿霉素实验组和对照组、丝裂霉素实验组和对照组,每组5只;各实验组荷瘤鼠灌胃给予具核梭杆菌菌液(10~9CFU),0.2 mL/d,1次/周。连续灌胃4周后,5-氟尿嘧啶实验组、阿霉素实验组、丝裂霉素实验组荷瘤鼠分别腹腔注射给予30.00 mg/(kg·d)、1.75 mg/(kg·d)、2.00 mg/(kg·d)对应药物,1次/d,连用7 d;奥沙利铂实验组、伊立替康实验组荷瘤鼠分别第1天腹腔注射给予29 mg/kg、66 mg/kg对应药物,其余6 d用生理盐水0.1 mL代替。各对照组荷瘤鼠除不灌胃具核梭杆菌菌液外,其余操作均与实验组相同。对比各实验组和对照组的瘤重和抑瘤率(IR%)。结果各组成瘤裸鼠一般情况均正常,肿瘤呈膨胀性生长,未见明显浸润或转移发生。各实验组荷瘤鼠的瘤重(g)均显著大于对照组荷瘤鼠[(1.42±0.15)vs(0.97±0.12),(1.76±0.16)vs(1.45±0.13),(1.50±0.09)vs(1.03±0.08),(1.38±0.07)vs(0.87±0.05),(1.26±0.08)vs(0.79±0.05);均P<0.05],IR%显著小于对照组荷瘤鼠[(27.55±2.83)vs(50.51±5.02),(10.20±1.78)vs(26.02±2.36),(23.47±2.76)vs(47.45±4.86),(29.59±3.02)vs(55.61±5.35),(35.71±3.47)vs(59.69±5.45);均P<0.05]。结论具核梭杆菌降低抗结直肠癌药物的敏感性。     

具核梭杆菌对结直肠癌细胞增殖、迁移及上皮间质转化作用的影响

【目的】评估具核梭杆菌对人结直肠癌细胞HCT116和人正常结肠上皮细胞HCoEpiC的增殖、黏附、凋亡、迁移、侵袭和上皮间质转化的影响。【方法】本研究用不同感染复数(MOI)Fusobacterium nucleatum ATCC 23726感染人结直肠癌细胞HCT116和人正常结肠上皮细胞HCoEpiC,建立感染模型;用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide,MTT]、平板克隆、细胞划痕及侵袭(transwell)实验检测两组细胞的增殖、迁移和侵袭的变化;用流式细胞仪检测两组细胞凋亡情况;通过Western blotting检测两组细胞上皮标记物上皮细胞钙黏蛋白(E-cadherin)、Catenin δ-1蛋白、间充质标记物N-钙粘蛋白(N-cadherin)和波形蛋白(vimentin)表达水平的变化。【结果】F.nucleatum可促进HCT116细胞增殖,诱导HCT116细胞的迁移和侵袭,但不能引起细胞凋亡;可抑制HCoEpiC细胞的增殖、迁移和侵袭,并加速其凋亡;对HCT116和HCoEpiC细胞表现出很强的粘附能力,致细胞分散和拉长,细胞间粘附减少;使HCT116和HCoEpiC细胞上皮标记物E-cadherin与Catenin δ-1的表达量减少,间充质标记物N-cadherin与vimentin的表达量上升,E-cadherin由细胞膜向细胞质转移。【结论】F.nucleatum可诱导结直肠癌细胞和人正常结肠上皮细胞发生上皮间质转化,但抑制人正常结肠细胞的增殖、迁移和侵袭,表现出与结直肠癌细胞相反的作用。     

肠道具核梭杆菌与结直肠癌的关系及其致病机制的研究进展

结直肠癌(colorectal cancer, CRC)为全球第三大常见癌症,死亡率位居第二。随着微生物组学技术的发展,近年来,研究发现,具核梭杆菌(Fusobacterium nucleatum,Fn)不仅参与口腔疾病和脑膜炎、心内膜炎、化脓性关节炎等口腔外感染性疾病的发生、发展,还可能通过促进结直肠上皮细胞增殖、促进机体炎症微环境、免疫调节等多种机制参与CRC的发生、发展,但具体致病机制还亟待阐明。基于此,现就Fn与CRC的关系和相关致病机制作一概述,为未来深入探究CRC生物预防及治疗提供理论依据。     

ω-3多不饱和脂肪酸抗肿瘤新途径——抑制具核梭杆菌黏附宿主细胞

【背景】大量文献报道ω-3多不饱和脂肪酸尤其是二十二碳六烯酸(Docosahexaenoic Acid,DHA)与二十碳五烯酸(Eicosapentaenoic Acid,EPA)具有抗肿瘤作用,但是其抗肿瘤机制还不够完善。【目的】探究ω-3多不饱和脂肪酸、具核梭杆菌以及结直肠癌三者之间的关联。【方法】在检测二十二碳六烯酸、二十碳五烯酸、α-亚麻酸(α-Linolenic Acid,ALA)等ω-3多不饱和脂肪酸对人结直肠腺癌细胞Caco-2、正常结肠上皮细胞NCM460生长影响的基础上,检测DHA等3种多不饱和脂肪酸对具核梭杆菌黏附人体细胞以及Fap2、FadA、RadD等具核梭杆菌毒力关键基因表达的影响。【结果】30μg/mL的DHA、EPA、ALA对Caco-2生长抑制分别为9.09%、4.95%、7.52%,而对NCM460生长抑制达31.15%、25.48%、29.11%,而且相关抑制作用仅具有浓度依赖性而无时间依赖性。经30μg/mL的DHA、EPA、ALA预处理的具核梭杆菌黏附Caco-2细胞的能力分别下降81.04%(P=0)、93.63%(P=0)和68.63%(P=0);而共培养时加入DHA、EPA、ALA对具核梭杆菌黏附Caco-2细胞的能力没有显著影响。同时,30μg/mLDHA处理导致F.nucleatum的Fap2基因显著下降10.22%(P=0.027);30μg/mL EPA处理导致FadA、Fap2基因分别显著下降23.49%(P=0)、15.09%(P=0.003);30μg/mL ALA处理导致FadA基因显著下降26.75%(P=0.012)。【结论】综合上述实验结果以及DHA、EPA、ALA仅能短时间抑制具核梭杆菌生长等文献报道,我们认为,DHA、EPA等ω-3多不饱和脂肪酸并非简单地直接杀伤或抑制肿瘤细胞和F.nucleatum;抑制FadA、Fap2等黏附相关基因表达,降低F.nucleatum黏附宿主细胞能力是其抗肿瘤作用的关键组成部分。ω-3多不饱和脂肪酸等活性物质对F.nucleatum等在结直肠肿瘤发生、发展中发挥重要作用的肠道细菌的影响与机制应深入开展研究。     

Fusobacterium nucleatum and colorectal cancer: A mechanistic overview

Colorectal cancer (CRC) is the third most prevalent cancer in the world. There are many risk factors involved in CRC. According to recent findings, the tumor microenvironment and feces samples of patients with CRC are enriched by Fusobacterium nucleatum. Thus, F. nucleatum is proposed as one of the risk factors in the initiation and progression of CRC. The most important mechanisms of Fusobacterium nucleatum involved in CRC carcinogenesis are immune modulation (such as increasing myeloid-derived suppressor cells and inhibitory receptors of natural killer cells), virulence factors (such as FadA and Fap2), microRNAs (such as miR-21), and bacteria metabolism. The aim of this review was to evaluate the mechanisms underlying the action of F. nucleatum in CRC.     

Outer membrane proteins as major antigens of Fusobacterium nucleatum

Abstract The immunochemical reactions of rabbit polyclonal antibodies directed to different preparations of Fusobacterium nucleatum i.e, whole cells, peptidoglycan associated proteins, a peptidoglycan-protein complex and a purified 40 kiloDalton (kDa) protein, were investigated on outer membrane preparations of Fusobacterium species and a restricted number of Leptotrichia buccalis after their separation on sodium dodecyl sulphate polyacrylamide gels and electrotransfer to nitrocellulose. All F. nucleatum strains had identical reaction patterns with the immune sera tested. Surface exposed parts of a restricted number of proteins with apparent molecular weights at 70 kDa (a doublet band), 60 kDa, 55 kDa and 40 kDa seemed to be major immunogens. Antigenic related proteins either of identical or slightly deviating electrophoretic mobilities to the 40-kDa protein were observed with the other members of Bacteroidaceae tested. The characteristic 70-kDa protein doublet seemed to be restricted to F. nucleatum although single protein bands of near identical molecular weights belonging to the other species tested also reacted. The data also indicate that the 60-kDa and 55-kDa polypeptides might be present in other species of Fusobacterium .     

A newly developed PCR-based method revealed distinct Fusobacterium nucleatum subspecies infection patterns in colorectal cancer

Fusobacterium nucleatum, which has four subspecies (nucleatum, animalis, vincentii and polymorphum), plays an important role in promoting colorectal cancer (CRC). However, as there is no efficient method of differentiating these subspecies in the context of a rich gut microbiota, the compositions in CRC remain largely unknown. In this study, a PCR-based differentiation method enabling profiling of F. nucleatum infection in CRC at the subspecies level was developed. Based on the analysis of 53 F. nucleatum genomes, we identified genetic markers specific to each subspecies and designed primers for the conserved sequences of those markers. The PCR performance of the primers was tested with F. nucleatum and non-nucleatum Fusobacterium strains, and complete consistence with taxonomy was achieved. Additionally, no non-specific amplification occurred when using human DNA. The method was then applied to faecal (n = 58) and fresh-frozen tumour tissue (n = 100) samples from CRC patients, and wide heterogeneity in F. nucleatum subspecies compositions in the gut microbiota among CRC patients was observed. Single-subspecies colonization was common, whereas coexistence of four subspecies was rare. Subspecies animalis was most prevalent, while nucleatum was not frequently detected. The results of this study contribute to our understanding of the pathogenicity of F. nucleatum at the subspecies level and the method developed has potential for clinical and epidemiological use.     

Isolation, purification and characterisation of 2-oxoglutarate reductase from Fusobacterium nucleatum

2-Oxoglutarate reductase from Fusobacterium nucleatum was isolated by thiol-disulphide interchange covalent chromatography. The enzyme was purified approximately 4000-fold and had a molecular mass of 68 kDa. The Michaelis constants for 2-oxoglutarate and NADH were 6.4 x 10(-5) and 0.4 x 10(-5), respectively. The involvement of sulphahydryl groups in catalysis was shown from the inhibition of 2-oxoglutarate reduction in the presence of 2,2'-dipyridyl disulphide and reactivation with 2-mercaptoethanol. Allosteric effectors did not alter the rate of the reaction, or the enzyme stability. With the exception of 2-oxoglutarate, none of the other oxo-acids such as oxaloacetate, pyruvate, 2-oxobutyrate and glyoxylate were reduced. Although 2-oxoglutarate oxidised NADPH to a limited extent (3%), the enzyme was almost entirely specific towards NADH. 2-Oxoglutarate reductase was stable at 45 degrees C for 10 min, while incubation at 60 degrees C abolished all activity.     

Fluorescence based measurements of Fusobacterium nucleatum coaggregation and of fusobacterial attachment to mammalian cells

Fusobacterium nucleatum is a common oral anaerobe associated with gingivitis, periodontal disease and preterm deliveries. Coaggregation among oral bacteria is considered to be a significant factor in dental plaque development. Adhesion to host cells was suggested to be important for the F. nucleatum virulence associated with oral inflammation and with preterm births. An uncharacterized fusobacterial galactose inhibitible adhesin mediates coaggregation of F. nucleatum 12230 and F. nucleatum PK1594 with the periodontal pathogen Porphyromonas gingivalis. This adhesin is also involved with the attachment of both fusobacterial strains to host cells. However, it has been suggested that additional unidentified fusobacterial adhesins are involved in F. nucleatum virulence associated with preterm births. In this study, a fluorescence-based high throughput sensitive and reproducible method was developed for measuring bacterial coaggregation and bacterial attachment to mammalian cells. Using this method we found that coaggregation of F. nucleatum 4H with P. gingivalis and its attachment to murine macrophages is less inhibitible by galactose than that of F. nucleatum PK1594. These findings suggest that F. nucleatum 4H can serve as a model organism for identifying nongalactose inhibitible F. nucleatum adhesins considered to be involved in fusobacterial attachment to mammalian cells.