Summary

遗传工程小鼠模型的散发性结肠直肠癌

Published: July 06, 2017
doi:

Summary

提出了通过节段性腺病毒感染建立结肠直肠癌基因工程小鼠模型的方法及其通过高分辨率结肠镜检查进行的监测。

Abstract

尽管具有易于适用性和成本效益的优点,但是基于肿瘤细胞注射的结直肠癌小鼠模型具有严重的局限性,并且不能准确模拟肿瘤生物学和肿瘤细胞传播。引入基因工程小鼠模型来克服这些局限性;然而,这种模型在技术上是苛刻的,特别是在大器官如结肠中仅需要单个肿瘤。

结果,开发了免疫活性的基因工程的结肠直肠癌小鼠模型,其发展高度均匀的肿瘤,并且可以用于肿瘤生物学研究以及治疗试验。肿瘤发展是通过复合条件突变小鼠中腺瘤病毒的远端结肠的手术,节段性感染开始的。可以通过结肠镜检查容易地检测和监测肿瘤。我们这里描述了节段性腺病毒感染的外科技术结肠, 通过高分辨率结肠镜检查监测肿瘤并呈现所得的结肠直肠肿瘤。

Introduction

结肠直肠癌(CRC)仍然是西方国家与癌症相关死亡的主要原因之一。 1尽管早期疾病患者的预后良好,但是在后期阶段诊断出许多肿瘤,尽管有许多治疗方案,预后有限。 2,3,4,5

目前大多数CRC的小鼠模型都是基于将衍生自细胞系或患者肿瘤的肿瘤细胞植入免疫缺陷小鼠。 6,7,8这导致局部,并且取决于注射部位和用于注射的肿瘤细胞,有时是转移性肿瘤。 9,10然而,所得到的异种移植模型具有巨大的作用r限制。它们必须建立在免疫缺陷小鼠中,从而消除肿瘤与宿主免疫系统之间的复杂相互作用。另外,由于肿瘤基质来自宿主细胞,所以人类肿瘤实质与鼠基质之间的相互作用是有缺陷的,因此不能代表疾病。这些缺陷可以通过使用注射用鼠细胞系来避免。然而,只有少数鼠CRC细胞系可用,并且与大多数可用的人类CRC细胞系相似,是单克隆和高度间变性的。总之,目前大多数目前可用的CRC小鼠模型是高度人为的,并不完全代表人类疾病。

CRC的遗传工程小鼠模型(GEMM)可以避免这些缺点,因为它们具有通过诱导结肠中CRC的关键突变而产生的真正的小鼠肿瘤。 12,13 这可以通过在结肠直肠粘膜中通过cre重组酶激活条件(floxed)种系突变来实现。在许多其他肿瘤实体的GEMM中,使用由组织特异性启动子驱动的种系(诱导型)cre表达,种系cre不能用于结肠,因为这导致整个结肠中的大量腺瘤通过良性肿瘤负荷导致死亡很年轻因此,在这里描述的模型中,使用表达cre的腺病毒载体来感染短的结肠段。这导致在研究者定义的时间点诱导该粘膜部分的肿瘤发生,导致腺瘤最终进展到侵袭性和转移性癌。肿瘤是真正的小鼠肿瘤,在完整的微环境中生长,因此能够模拟包括肿瘤 – 宿主相互作用和转移性级联在内的整体结直肠癌发生。这个模型是因此是癌症生物学和临床前治疗试验研究的有吸引力的平台。

CRC遗传工程小鼠模型的一个主要缺点是其技术复杂性。以前已经描述了使用直肠腺苷灌注剂的小鼠携带Floced Apc等位基因的局部妊娠然而,这种技术,肠肿瘤的发生率,多样性和位置可能是高度可变的。因此,开发了通过手术夹紧待诱导的片段限制腺病毒感染的技术。 13我们修改了这一程序,以改善动物福利,并减少死亡率和肿瘤数量。有了这个协议,所有具有小型啮齿动物手术经验的实验室都应该能够复制模型并产生高度可重复性且容易接近结肠镜检查的肿瘤。取决于条件m用于肿瘤发生的术语,腺瘤的全谱,侵袭性癌和转移灶可以观察到。由于肿瘤位于远端结肠,因此在该模型中可以很容易进行连续内镜评估。

Protocol

这里提出的动物实验由机构和政府动物护理和使用委员会进行独立审查和批准,并根据实验动物科学协会联合会(FELASA)指导进行。采取一切可能的措施,尽量减少包括麻醉和镇痛在内的痛苦,或必要时提早安乐死。 局部肿瘤感染通过外科手术感染 手术动物的准备 注意:几乎任何条件(“floxed”)突变可以通过这里描述的方法诱导。推荐在大…

Representative Results

如果充分进行,> 85%的动物会发展成肿瘤。这里介绍的外科手术的死亡率<5%,结肠镜检查的死亡率几乎不存在。在大多数小鼠中,检测到单个病变;在大约30%的2〜3个小腺瘤中,可以检测到肿瘤诱导后2-3周内通常融合到单个肿瘤。 所得肿瘤的表型和生物学行为高度依赖于动物的条件突变。 Apc的局部cre介导的敲除足以诱?…

Discussion

虽然它们通常易于产生和维持,但基于细胞系注射的经典CRC小鼠模型是人为的,并且不能完全重现人类疾病。因此,GEMM已经开发。第一个CRC GEMM是Apc Min小鼠,其在Apc基因中携带杂合的无效突变,因此模拟人类遗传性家族性腺瘤性息肉病(FAP)。然而,Apc Min小鼠总是发展出不限于结肠的多个肠腺瘤;此外,腺瘤形成的时间和确切位置是随机的,并且当腺瘤可以进展之前,随着小鼠死…

Divulgaciones

The authors have nothing to disclose.

Acknowledgements

这项工作致力于莫里茨·科赫教授的记忆。

Materials

Reagents / consumables
Dulbecco's Phosphate Buffered Saline Life Technologies GmbH 14190169
Trypsin-EDTA (0.25%, Phenol-Red) Life Technologies GmbH 25200072
Normal saline 0.9% (E154) Serumwerk Bernburg AG 10013
Aqua ad injectabilia B. Braun Melsungen AG 235144
Ad5CMV-Cre (adenovirus, c = 2E+11 PFU/mL) Gene Transfer Vector Core
University of Iowa
15 mL, 50 mL centrifuge tubes Greiner Bio-One GmbH 188271/227270
Eppendorf tubes 1.5 mL/ 2 mL Sarstedt AG & Co. 72,695,400
Petri dish PS 100/15 mm (sterile, Nuclon) Fisher Scientific GmbH 10508921/ NUNC150350
1 mL Syringe (without dead volume) – Injekt-F SOLO Braun/neoLab 194291661
30G injection needle BECTON DICKINSON 304000
Name Company Catalog Number Comments
Analgesia / anesthesia
Sevoflurane (Sevoflurane AbbVie) AbbVie Germany GmbH & Co. KG
Medical oxygen Air Liquide Medical GmbH
Buprenorphine (Temgesic) Indivior Eu Ltd.
Bepanthen – ophthalmic ointment Bayer Vital GmbH 10047757
Table Top Research Anesthesia Machine x/O2 Flush w/ Sevoflurane Vaporizer Parkland Scientific V3000PS/PK
Name Company Catalog Number Comments
Surgical Equipment
Cellulose swabs Lohmann & Rauscher Deutschland 13356
Insulin syringe EMG 1 mL (with 30G cannula) B. Braun Melsungen AG 9161627S
Fine Bore Tubing (bore: 0.28 mm/ diameter: 0.61mm) Smiths Medical Deutschland 800/100/100
Micro-Adson Forceps Fine Science Tools 11018-12
Iris Scissor – ToughCut Fine Science Tools 14058-11
Olsen-Hegar Needle Holder Fine Science Tools 12002-12
AutoClip Kit Fine Science Tools 12020-00
PDS Z1012H 6/0 C1 (surgical suture) Johnson & Johnson Medical GmbH Z1012H
Curved Micro Serrefine Vascular Clamp Fine Science Tools 18055-05
Fogarty Spring Clips Edwards CDSAFE 6
Hot Plate 062 Labotect 13854
Isis – Hair shaver Aesculap – Braun
Name Company Catalog Number Comments
Colonoscopy
Cold Light Fountain XENON 175 SCB Karl Storz 20132101-1 Karl Storz Coloview System Mainz
Fiber Optic Light Cable Karl Storz 69495NL Karl Storz Coloview System Mainz
TRICAM Three-Chip Camera Head Karl Storz 20221030 Karl Storz Coloview System Mainz
TRICAM SLII Camera Control Unit Karl Storz 20223011-1 Karl Storz Coloview System Mainz
15" Flat Screen Monitor EndoVue Karl Storz 9415NN Karl Storz Coloview System Mainz
HOPKINS Straight Forward Telescope
diameter 1.9 mm; length 10 cm
autoclavable
fiber optic light transmission incorporated
Karl Storz 64301AA
Protection and Examination Sheath Karl Storz 61029C

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Betzler, A. M., Kochall, S., Blickensdörfer, L., Garcia, S. A., Thepkaysone, M., Nanduri, L. K., Muders, M. H., Weitz, J., Reissfelder, C., Schölch, S. A Genetically Engineered Mouse Model of Sporadic Colorectal Cancer. J. Vis. Exp. (125), e55952, doi:10.3791/55952 (2017).

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