Name: utilizing high resolution ultrasound to monitor tumor onset and growth in genetically engineered pancreatic cancer models
Uploaded: 2018-04-07T13:00:00
Description: Watch this Scientific Journal Video about Utilizing High Resolution Ultrasound to Monitor Tumor Onset and Growth in Genetically Engineered Pancreatic Cancer Models at JoVE.com

This research was supported by the Deutsche Krebshilfe (Max Eder Group to AN: 110972), a DGVS doctoral thesis scholarship (to SMB), and an Else-Kr&#246;ner-Fresenius-Foundation scholarship (to RGG) at the University Medical Center Goettingen. We thank Jutta Blumberg and Ulrike Wegner for expert technical assistance. We also thank all animal technicians at the animal facility of the University Medical Center Goettingen for mouse keeping. All experiments were performed according to German animal welfare regulations.

This protocol is in accordance with the animal care guidelines at the University Medical Centre Goettingen, Germany (33.9-42502-04-15/2056). Depending on specific requirements of individual animal review boards, some of the protocol steps could be modified accordingly.
1. Abdominal Palpation of KPC Mice
<ol>
	<li>To avoid unnecessary ultrasound scans, palpate the mouse abdomen to identify mice which might possibly bear an intraabdominal lesion and should subsequently undergo abdominal ultras...

<ol>
	<li>Kersten, K., de Visser, K. E., van Miltenburg, M. H., Jonkers, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+engineered+mouse+models+in+oncology+research+and+cancer+medicine.">Genetically engineered mouse models in oncology research and cancer medicine.</a> EMBO Molecular Medicine. 9 (2), 137-153 (2017).</li><li>Olive, K. P., Politi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Translational therapeutics in genetically engineered mouse models of cancer. (2), 131-143 (2014).</li><li>Westphalen, C. B., Olive, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+engineered+mouse+models+of+pancreatic+cancer.">Genetically engineered mouse models of pancreatic cancer.</a> The Cancer Journal. 18 (6), 502-510 (2012).</li><li>Hingorani, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trp53R172H+and+KrasG12D+cooperate+to+promote+chromosomal+instability+and+widely+metastatic+pancreatic+ductal+adenocarcinoma+in+mice.">Trp53R172H and KrasG12D cooperate to promote chromosomal instability and widely metastatic pancreatic ductal adenocarcinoma in mice.</a> Cancer Cell. 7 (5), 469-483 (2005).</li><li>Frese, K. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=nab-Paclitaxel+potentiates+gemcitabine+activity+by+reducing+cytidine+deaminase+levels+in+a+mouse+model+of+pancreatic+cancer.">nab-Paclitaxel potentiates gemcitabine activity by reducing cytidine deaminase levels in a mouse model of pancreatic cancer.</a> Cancer Discovery. 2 (3), 260-269 (2012).</li><li>Paredes, J. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+non-invasive+method+of+quantifying+pancreatic+volume+in+mice+using+micro-MRI.">A non-invasive method of quantifying pancreatic volume in mice using micro-MRI.</a> PLoS One. 9 (3), e92263 (2014).</li><li>Boj, S. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organoid+models+of+human+and+mouse+ductal+pancreatic+cancer.">Organoid models of human and mouse ductal pancreatic cancer.</a> Cell. 160 (1-2), 324-338 (2015).</li><li>Aung, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunotargeting+of+Integrin+alpha6beta4+for+Single-Photon+Emission+Computed+Tomography+and+Near-Infrared+Fluorescence+Imaging+in+a+Pancreatic+Cancer+Model.">Immunotargeting of Integrin alpha6beta4 for Single-Photon Emission Computed Tomography and Near-Infrared Fluorescence Imaging in a Pancreatic Cancer Model.</a> Molecular Imaging. 15, (2016).</li><li>Akladios, C. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+microCT+structural+imaging+to+preclinical+evaluation+of+hepatocellular+carcinoma+chemotherapeutics+on+orthotopic+graft+in+ACI+rats.">Contribution of microCT structural imaging to preclinical evaluation of hepatocellular carcinoma chemotherapeutics on orthotopic graft in ACI rats.</a> Bulletin du Cancer. 98 (2), 120-132 (2011).</li><li>Neesse, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CTGF+antagonism+with+mAb+FG-3019+enhances+chemotherapy+response+without+increasing+drug+delivery+in+murine+ductal+pancreas+cancer.">CTGF antagonism with mAb FG-3019 enhances chemotherapy response without increasing drug delivery in murine ductal pancreas cancer.</a> Proceedings of the National Academy of Science USA. 110 (30), 12325-12330 (2013).</li><li>Sastra, S. A., Olive, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+murine+pancreatic+tumors+by+high-resolution+ultrasound.">Quantification of murine pancreatic tumors by high-resolution ultrasound.</a> Methods in Molecular Biology. 980, 249-266 (2013).</li></ol>

With this protocol, a detailed description for quantifying pancreatic tumors using high-resolution abdominal ultrasound imaging in genetically engineered mouse models is provided. Recently, Sastra et al. published a detailed description how to quantify pancreatic tumors in mouse models, but no visualized instructions about the preparation and handling as prerequisite for all further steps were shown11. The overall goal of this manuscript is to provide a comprehensive visual guide for high...

Genetically engineered mouse models have gained an increasing importance in cancer research due to their ability to closely recapitulate the complex nature of human carcinogenesis1,2,3. One of the most frequently used models to study pancreatic cancer development, progression and therapeutic response is characterized by an activating mutation in the Kras oncogene combined with an inactivation of the tumor suppressor p534. This LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mouse model mimics the step-wise progression from pre-invasive pancreatic intraepithelial neoplasia (PanIN) lesions to invasive carcinoma. Phenotypically, nearly all mice develop PDAC within the first six months after birth. However, compared to transplanted models, the KPC model reveals a highly variable tumor onset from 8 weeks to several months4. Once pancreatic tumors reach a certain size (5-9 mm in diameter), tumor growth accelerates rapidly and mice will have to be enrolled in preclinical trials5. Therefore, the exact detection of tumor onset and tumor size is an essential prerequisite for preclinical study logistics and therapy monitoring. In general, several approaches like magnetic resonance imaging (MRI)6, computed tomography scanning7,8,9 or high resolution ultrasound can be employed to conduct tumor screening and therapy10. Each technique has its advantages and drawbacks. Although MRI-or computed tomography (CT) -imaging allows high resolution data acquisition as well as accurate volume calculation, prolonged examination time under general sedation, and very expensive equipment is required, and does not permit frequent scanning over a long period of time. In contrast, small animal ultrasonography is an established method that can be employed to screen for abdominal pathologies in mice11. Advantages of this imaging method are short scanning times, high resolution, and the possibility to use doppler ultrasound or contrast enhanced ultrasound (CEUS) to visualize perfusion of organs in parallel. However, anatomical knowledge, 3D imagination and thorough practical training are required for correct image interpretation.
In the following article, a detailed protocol for utilizing high resolution ultrasound in the KPC model is provided. Furthermore, standard ultrasound images are depicted and labelled with organ structures to facilitate orientation for the investigator.

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			<td>Visual Sonics Vevo2100 High Resolution Ultrasound System, including imaging stage and anesthesia line</td>
			<td>FUJIFILM VisualSonics Inc, Canada</td>
			<td>VS-11945</td>
			<td></td>
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			<td>Vevo 2100 MicroScan Transducer MS-550-D (22-55MHz)</td>
			<td>FUJIFILM VisualSonics Inc, Canada</td>
			<td>VS-11874</td>
			<td></td>
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			<td>Vevo Anesthesia System (anesthesia induction chamber with fresh and waste gas inlet)</td>
			<td>FUJIFILM VisualSonics Inc, Canada</td>
			<td>SA-12055</td>
			<td></td>
		</tr>
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			<td>Vevo Imaging Station (working stage with nose cone for anesthesia supply)</td>
			<td>FUJIFILM VisualSonics Inc, Canada</td>
			<td>SA-11982</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;electronic pet clippers</td>
			<td>Panasonic Marketing Europe, Germany</td>
			<td>5025232484324</td>
			<td>Panasonic ER-PA10-s</td>
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			<td>Labotect Hot plate</td>
			<td>Labor tech G&#246;ttingen, Germany</td>
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			<td>veterinary isoflurane</td>
			<td>Abbvie, Germany</td>
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			<td>depilatory cream</td>
			<td>RB healthcare UK, United Kingdom</td>
			<td>8218535</td>
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			<td>70% ethanol (v/v) in distilled water</td>
			<td>TH. Geyer, Germany</td>
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			<td>ultrasound gel</td>
			<td>Asmuth, Germany</td>
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			<td>tissue wipes</td>
			<td>Kimberly-Clark Germany, Germany</td>
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			<td>cotton tips</td>
			<td>Meditrade, Germany</td>
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			<td>glass bowl for ultrasound gel</td>
			<td>ARC France, France</td>
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			<td>water bowl</td>
			<td>W &#38; P Trading Co., USA</td>
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			<td>gauze sponges</td>
			<td>Fuhrmann, Germany</td>
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utilizing high resolution ultrasound to monitor tumor onset and growth in genetically engineered pancreatic cancer models

The LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mouse model represents an established and frequently used transgenic model to evaluate novel therapies in pancreatic cancer. Tumor onset is variable in the KPC model between 8 weeks and several months. Therefore, non-invasive imaging tools are required to screen for tumor onset and monitor for response to treatment. To address this issue, different approaches have emerged over the last years. High resolution ultrasound has major advantages such as non-invasiveness, fast session times and a high image resolution without radiation exposure. However, ultrasound in mice is not trivial and sufficient anatomical knowledge and practical skills are required to successfully perform high resolution ultrasound in preclinical pancreatic cancer models. With the following article, a detailed hands-on guide for abdominal ultrasound in murine models with a particular focus on endogenous pancreatic cancer models is presented. Furthermore, a summary of common mistakes and how to avoid them is provided.

Ultrasound imaging is a versatile and non-invasive technique that is used to address several issues in murine models of human diseases. Compared to all other imaging approaches major advantages are high-throughput, cost efficiency, short acquisition time and real-time imaging. However, this tool needs expertise to generate accurate, high quality images. Particularly in the case of unwanted artefacts at least some experience with ultrasound imaging in general is very helpful. In relation t...

Watch this Scientific Journal Video about Utilizing High Resolution Ultrasound to Monitor Tumor Onset and Growth in Genetically Engineered Pancreatic Cancer Models at JoVE.com

Utilizing High Resolution Ultrasound to Monitor Tumor Onset and Growth in Genetically Engineered Pancreatic Cancer Models

This article describes the utilization of high-resolution ultrasound in genetically engineered pancreatic cancer mice. The primary aim is to provide a detailed instruction for detection and evaluation of endogenous pancreatic tumors.

The LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mouse model represents an established and frequently used transgenic model to evaluate novel ...

There are various genetically engineered mouse models to study pancreatic cancer. The most commonly used model is the Kras, p53 mouse model that harbors an activating mutation in the Kras oncogene, and an inactivating mutation in the p53 tumor suppressor gene. Both mutations are conditionally activated by the Pdx-Cre promoter.This Kras, p53, Pdx-Cre mouse model, in short KPC model, develops endogenous pancreatic tumors between the age of two to six month. In preparation of your ultrasound procedure, the following equipment should be prepared and ready to use. For high resolution ultrasound, a stationary ultrasound device is used.The ultrasound procedure is conducted in general anesthesia using isoflurane evaporation. Once the mouse is under deep sedation, it is transferred to the green working stage. After the ultrasound procedure, the mouse should be placed in a pre-heated cage to accelerate recovery.Tumor development is highly variable in the KPC mouse model. To avoid unnecessary ultrasound screening procedures, we usually perform abdominal palpation weekly starting from the age of two months. Gently, palpate the mouse abdomen up and down to detect any pancreatic tumors.Keep in mind that hard feces may mimic abdominal tumor masses. After initiation of general anesthesia, in a separate induction chamber, the mouse is carefully placed onto the green and pre-heated working stage. During the ultrasound procedure, isoflurane is continuously supplied via the nose cone.Fix the trandsucer head at the top of your working stage by using the mounting system. Perform the foot-pinch test to make sure the mouse is under deep anesthesia. Afterwards, the mouse is fixed onto the working platform using medical strips.It is crucial to completely remove the abdominal fur prior to the ultrasound procedure, to avoid any artifacts. First, carefully shave off the mouse fur. Great care should be taken to avoid any superficial skin lacerations using the pet clipper.Second, apply a thin layer of the depilatory cream onto the shaved area. Completely remove the cream using moist tissues. Apply abundant ultrasound gel onto the mouse abdomen, and a thin layer of gel directly onto the ultrasound probe.Adjust the transducer onto the abdomen using soft pressure. Heavy compression of the mouse abdomen may lead to respiratory or circulatory impairment, and should be avoided. Scan up and down and adjust the frame of the working platform and the wheels for the x and y axis.Some tumors may only be visible by changing the initial position of the mouse. To correctly interpret B-mode ultrasound images, basic anatomical knowledge is required. In the KPC mouse model, pancreatic tumors can be detected in the head, body, or tail of the pancreas.The tumors usually demarcate as hypoechoic masses. Due to their desmoplastic features, these tumors are usually hard to compress by the ultrasound probe. Following the ultrasound, completely remove the ultrasound gel and gently place the mouse in the pre-heated recovery cage.Once you identified a tumor, scan up and down to get an impression of the total size, and measure the largest diameter by using the ultrasound caliper. For the exact volume calculation, we use the formula of an ellipsoid. After finishing the measurement of the first plane, either rotate the scan-head by 90 degree, in a longitudinal position, or turn the mouse to its side, to detect the tumor's longitudinal expansion.For the evaluation of novel therapeutic approaches, it is important to determine the initial tumor volume and the tumor growth kinetics during treatment. During pre-clinical trials, abdominal ultrasound can be repeated every three to four days to monitor tumor growth.

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Research

JoVE Journal

Cancer Research

A Genetically Engineered Mouse Model of Sporadic Colorectal Cancer

Despite the advantages of easy applicability and cost-effectiveness, colorectal cancer mouse models based on tumor cell injection have severe limitations and do not accurately simulate tumor biology and tumor cell dissemination. Genetically engineered mouse models have been introduced to overcome these limitations; however, such models are technically demanding, especially in large organs such as the colon in which only a single tumor is desired.
As a result, an immunocompetent, genetically engineered mouse model of colorectal cancer was developed which develops highly uniform tumors and can be used for tumor biology studies as well as therapeutic trials. Tumor development is initiated by surgical, segmental infection of the distal colon with adeno-cre virus in compound conditionally mutant mice. The tumors can be easily detected and monitored via colonoscopy. We here describe the surgical technique of segmental adeno-cre infection of the colon, the surveillance of the tumor via high-resolution colonoscopy and present the resulting colorectal tumors.

A protocol for the establishment of a genetically engineered mouse model of colorectal cancer by segmental adeno-cre infection and its surveillance via high-resolution colonoscopy is presented.

Despite the advantages of easy applicability and cost-effectiveness, colorectal cancer mouse models based on tumor cell injection have severe limitations ...

Radionuclide-fluorescence Reporter Gene Imaging to Track Tumor Progression in Rodent Tumor Models

Metastasis is responsible for most cancer deaths. Despite extensive research, the mechanistic understanding of the complex processes governing metastasis remains incomplete. In vivo models are paramount for metastasis research, but require refinement. Tracking spontaneous metastasis by non-invasive in vivo imaging is now possible, but remains challenging as it requires long-time observation and high sensitivity. We describe a longitudinal combined radionuclide and fluorescence whole-body in vivo imaging approach for tracking tumor progression and spontaneous metastasis. This reporter gene methodology employs the sodium iodide symporter (NIS) fused to a fluorescent protein (FP). Cancer cells are engineered to stably express NIS-FP followed by selection based on fluorescence-activated cell sorting. Corresponding tumor models are established in mice. NIS-FP expressing cancer cells are tracked non-invasively in vivo at the whole-body level by positron emission tomography (PET) using the NIS radiotracer [18F]BF4-. PET is currently the most sensitive in vivo imaging technology available at this scale and enables reliable and absolute quantification. Current methods either rely on large cohorts of animals that are euthanized for metastasis assessment at varying time points, or rely on barely quantifiable 2D imaging. The advantages of the described method are: (i) highly sensitive non-invasive in vivo 3D PET imaging and quantification, (ii) automated PET tracer production, (iii) a significant reduction in required animal numbers due to repeat imaging options, (iv) the acquisition of paired data from subsequent imaging sessions providing better statistical data, and (v) the intrinsic option for ex vivo confirmation of cancer cells in tissues by fluorescence microscopy or cytometry. In this protocol, we describe all steps required for routine NIS-FP-afforded non-invasive in vivo cancer cell tracking using PET/CT and ex vivo confirmation of in vivo results. This protocol has applications beyond cancer research whenever in vivo localization, expansion and long-time monitoring of a cell population is of interest.

We describe a protocol for preclinical in vivo tracking of cancer metastasis. It is based on a radionuclide-fluorescence reporter combining the sodium iodide symporter, detected by non-invasive [18F]tetrafluoroborate-PET, and a fluorescent protein for streamlined ex vivo confirmation. The method is applicable for preclinical in vivo cell tracking beyond tumor biology.

Metastasis is responsible for most cancer deaths. Despite extensive research, the mechanistic understanding of the complex processes governing metastasis ...

In Vivo Inhibition of MicroRNA to Decrease Tumor Growth in Mice

MicroRNAs (miRNAs) are important regulators of gene expression through their ability to destabilize mRNA and inhibit translation of target mRNAs. An ever-increasing number of studies have identified miRNAs as potential biomarkers for cancer diagnosis and prognosis, and also as therapeutic targets, adding an extra dimension to cancer evaluation and treatment. In the context of thyroid cancer, tumorigenesis results not only from mutations in important genes, but also from the overexpression of many miRNAs. Accordingly, the role of miRNAs in the control of thyroid gene expression is evolving as an important mechanism in cancer. Herein, we present a protocol to examine the effects of miRNA-inhibitor delivery as a therapeutic modality in thyroid cancer using human tumor xenograft and orthotopic mouse models. After engineering stable thyroid tumoral cells expressing GFP and luciferase, cells are injected into nude mice to develop tumors, which can be followed by bioluminescence. The in vivo inhibition of a miRNA can reduce tumor growth and upregulate miRNA gene targets. This method can be used to assess the importance of a determined miRNA in vivo, in addition to identifying new therapeutic targets.

This protocol describes xenograft and orthotopic mouse models of human thyroid tumorigenesis as a platform to test microRNA-based inhibitor treatments. This approach is ideal to study the function of non-coding RNAs and their potential as new therapeutic targets.

MicroRNAs (miRNAs) are important regulators of gene expression through their ability to destabilize mRNA and inhibit translation of target mRNAs. An ...

Ultrasound-Guided Orthotopic Implantation of Murine Pancreatic Ductal Adenocarcinoma

The recent success of immune checkpoint blockade in melanoma and lung adenocarcinoma has galvanized the field of immuno-oncology as well as revealed the limitations of current treatments, as the majority of patients do not respond to immunotherapy. Development of accurate preclinical models to quickly identify novel and effective therapeutic combinations are critical to address this unmet clinical need. Pancreatic ductal adenocarcinoma (PDA) is a canonical example of an immune checkpoint blockade resistant tumor with only 2% of patients responding to immunotherapy. The genetically engineered KrasG12D+/-;Trp53R172H+/-;Pdx-1 Cre (KPC) mouse model of PDA recapitulates human disease and is a valuable tool for assessing therapies for immunotherapy resistant in the preclinical setting, but time to tumor onset is highly variable. Surgical orthotopic tumor implantation models of PDA maintain the immunobiological hallmarks of the KPC tissue-specific tumor microenvironment (TME) but require a time-intensive procedure and introduce aberrant inflammation. Here, we use an ultrasound-guided orthotopic tumor implantation model (UG-OTIM) to non-invasively inject KPC-derived PDA cell lines directly into the mouse pancreas. UG-OTIM tumors grow in the endogenous tissue site, faithfully recapitulate histological features of the PDA TME, and reach enrollment-sized tumors for preclinical studies by four weeks after injection with minimal seeding on the peritoneal wall. The UG-OTIM system described here is a rapid and reproducible tumor model that may allow for high throughput analysis of novel therapeutic combinations in the murine PDA TME.

We describe a protocol for the ultrasound guided implantation of murine-derived pancreatic ductal adenocarcinoma cell lines directly into the native tumor site. This approach resulted in pancreatic tumors detectable by ultrasound scanning within 2-4 weeks of injection, and significantly reduced the proportion tumor cell seeding on the peritoneal wall as compared to surgical orthotopic implantation.

The recent success of immune checkpoint blockade in melanoma and lung adenocarcinoma has galvanized the field of immuno-oncology as well as revealed the ...

Isolation of Proximal Fluids to Investigate the Tumor Microenvironment of Pancreatic Adenocarcinoma

Pancreatic adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death, and soon to become the second. There is an urgent need of variables associated to specific pancreatic pathologies to help preoperative differential diagnosis and patient profiling. Pancreatic juice is a relatively unexplored body fluid, which, due to its close proximity to the tumor site, reflects changes in the surrounding tissue. Here we describe in detail the intraoperative collection procedure. Unfortunately, translating pancreatic juice collection to murine models of PDAC, to perform mechanistic studies, is technically very challenging. Tumor interstitial fluid (TIF) is the extracellular fluid, outside blood and plasma, which bathes tumor and stromal cells. Similarly to pancreatic juice, for its property to collect and concentrate molecules that are found diluted in plasma, TIF can be exploited as an indicator of microenvironmental alterations and as a valuable source of disease-associated biomarkers. Since TIF is not readily accessible, various techniques have been proposed for its isolation. We describe here two simple and technically undemanding methods for its isolation: tissue centrifugation and tissue elution.

Pancreatic juice is a precious source of biomarkers for human pancreatic cancer. We describe here a method for intraoperative collection procedure. To overcome the challenge of adopting this procedure in murine models, we suggest an alternative sample, tumor interstitial fluid, and describe here two protocols for its isolation.

Pancreatic adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death, and soon to become the second. There is an urgent need of variables ...

Analysis of Lymph Node Volume by Ultra-High-Frequency Ultrasound Imaging in the Braf/Pten Genetically Engineered Mouse Model of Melanoma

Tyr::CreER+,BrafCA/+,Ptenlox/lox&#160;genetically engineered mice (Braf/Pten mice) are widely used as an in vivo model of metastatic melanoma. Once a primary tumor has been induced by tamoxifen treatment, an increase in metastatic burden is observed within 4-6 weeks after induction. This paper shows how Ultra-High-Frequency UltraSound (UHFUS) imaging can be exploited to monitor the increase in metastatic involvement of the inguinal lymph nodes by measuring the increase in their volume.
The UHFUS system is used to scan anesthetized mice with a UHFUS linear probe (22-55 MHz, axial resolution 40 &#181;m). B-mode images from the inguinal lymph nodes (both left and right sides) are acquired in a short-axis view, positioning the animals in dorsal recumbency. Ultrasound records are acquired using a 44 &#181;m step size on a motorized mechanical arm. Afterward, two-dimensional (2D) B-mode acquisitions are imported into the software platform for ultrasound image post-processing, and inguinal lymph nodes are identified and segmented semi-automatically in the acquired cross-sectional 2D images. Finally, a total reconstruction of the three-dimensional (3D) volume is automatically obtained along with the rendering of the lymph node volume, which is also expressed as an absolute measurement.
This non-invasive in vivo technique is very well tolerated and allows the scheduling of multiple imaging sessions on the same experimental animal over 2 weeks. It is, therefore, ideal to assess the impact of pharmacological treatment on metastatic disease.

Melanoma is a very aggressive disease that quickly spreads to other organs. This protocol describes the application of ultra-high-frequency ultrasound imaging, coupled with 3D rendering, to monitor the volume of the inguinal lymph nodes in the Braf/Pten mouse model of metastatic melanoma.

Tyr::CreER+,BrafCA/+,Ptenlox/lox&#160;genetically engineered mice (Braf/Pten mice) are widely used as an in vivo model of metastatic melanoma. Once a ...

Molecular and Immunologic Techniques in a Genetically Engineered Mouse Model of Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and is typically driven by a single mutation in the KIT receptor. Across tumor types, numerous mouse models have been developed in order to investigate the next generation of cancer therapies. However, in GIST, most in vivo studies use xenograft mouse models which have inherent limitations. Here, we describe an immunocompetent, genetically engineered mouse model of gastrointestinal stromal tumor harboring a KitV558&#916;/+ mutation. In this model, mutant KIT, the oncogene responsible for most GISTs, is driven by its endogenous promoter leading to a GIST which mimics the histological appearance and immune infiltrate seen in human GISTs. Furthermore, this model has been used successfully to investigate both targeted molecular and immune therapies. Here, we describe the breeding and maintenance of a KitV558&#916;/+ mouse colony. Additionally, this paper details the treatment and procurement of GIST, draining mesenteric lymph node, and adjacent cecum in KitV558&#916;/+ mice, as well as sample preparation for molecular and immunologic analyses.

The goal of this manuscript is to describe the KitV558&#916;/+&#160;mouse model and techniques for successful dissection and processing of mouse specimens.

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and is typically driven by a single mutation in the KIT receptor. Across tumor ...

Zebrafish Larvae as a Model to Evaluate Potential Radiosensitizers or Protectors

Zebrafish are extensively used in several kinds of research because they are one of the easily maintained vertebrate models and exhibit several features of a unique and convenient model system. As highly proliferative cells are more susceptible to radiation-induced DNA damage, zebrafish embryos are a front-line in vivo model in radiation research. In addition, this model projects the effect of radiation and different drugs within a short time, along with major biological events and associated responses. Several cancer studies have used zebrafish, and this protocol is based on the use of radiation modifiers in the context of radiotherapy and cancer. This method can be readily used to validate the effects of different drugs on irradiated and control (non-irradiated) embryos, thus identifying drugs as radio sensitizing or protective drugs. Although this methodology is used in most drug screening experiments, the details of the experiment and the toxicity assessment with the background of X-ray radiation exposure are limited or only briefly addressed, making it difficult to perform. This protocol addresses this issue and discusses the procedure and toxicity evaluation with a detailed illustration. The procedure describes a simple approach for using zebrafish embryos for radiation studies and radiation-based drug screening with much reliability and reproducibility.

The zebrafish has recently been exploited as a model to validate potential radiation modifiers. The present protocol describes the detailed steps to use zebrafish embryos for radiation-based screening experiments and some observational approaches to evaluate the effect of different treatments and radiation.

Zebrafish are extensively used in several kinds of research because they are one of the easily maintained vertebrate models and exhibit several features ...

High-Resolution Ultrasonography for the Analysis of Orthotopic ATC Tumors in a Genetically Engineered Mouse Model

Anaplastic thyroid carcinoma (ATC) is associated with a poor prognosis and short median survival time, but no effective treatment improves the outcomes significantly. Genetically engineered murine models that mimic ATC&#39;s progression may help researchers to study treatments for this disease. Crossing three different genotypes of mice, a TPO-cre/ERT2; BrafCA/wt; Trp53&#916;ex2-10/&#916;ex2-10&#160;transgenic ATC model was developed. The ATC murine model was induced by an intraperitoneal injection of tamoxifen with overexpression of BrafV600E and deletion of Trp53, and the tumors were generated within about 1 month. High-resolution ultrasound was applied to investigate the tumor initiation and progression, and the dynamic growth curve was obtained by measuring the tumor sizes. Compared to magnetic resonance imaging (MRI) and computed tomography scanning, ultrasound has advantages in observing the ATC murine model, such as being noninvasive, portable, in real-time, and without radiation exposure. High-resolution ultrasound is suitable for dynamic and multiple measurements. However, ultrasonographic examination of the thyroid in mice requires relevant anatomical knowledge and experience. This article provides a detailed procedure for utilizing high-resolution ultrasound to scan tumors in the transgenic ATC model. Meanwhile, ultrasonic parameter adjustment, ultrasound scanning skills, anesthesia and recovery of the animals, and other elements that need attention during the process are listed.

The present protocol describes high-frequency ultrasonography for visualizing the entire mouse thyroid gland and monitoring the growth of anaplastic thyroid carcinoma.

Anaplastic thyroid carcinoma (ATC) is associated with a poor prognosis and short median survival time, but no effective treatment improves the outcomes ...

Somatic Genome-Engineered Mouse Models Using In Vivo Microinjection and Electroporation

Germline genetically engineered mouse models (G-GEMMs) have provided valuable insight into in vivo gene function in development, homeostasis, and disease. However, the time and cost associated with colony creation and maintenance are high. Recent advances in CRISPR-mediated genome editing have allowed the generation of somatic GEMMs (S-GEMMs) by directly targeting the cell/tissue/organ of interest.
The oviduct, or fallopian tube in humans, is considered the tissue-of-origin of the most common ovarian cancer, high-grade serous ovarian carcinomas (HGSCs). HGSCs initiate in the region of the fallopian tube distal to the uterus, located adjacent to the ovary, but not the proximal fallopian tube. However, traditional mouse models of HGSC target the entire oviduct, and thus do not recapitulate the human condition. We present a method of DNA, RNA, or ribonucleoprotein (RNP) solution microinjection into the oviduct lumen and in vivo electroporation to target mucosal epithelial cells in restricted regions along the oviduct. There are several advantages of this method for cancer modeling, such as 1) high adaptability in targeting the area/tissue/organ and region of electroporation, 2) high flexibility in targeted cell types (cellular pliancy) when used in combination with specific promoters for Cas9 expression, 3) high flexibility in the number of electroporated cells (relatively low frequency), 4) no specific mouse line is required (immunocompetent disease modeling), 5) high flexibility in gene mutation combination, and 6) possibility of tracking electroporated cells when used in combination with a Cre reporter line. Thus, this cost-effective method recapitulates human cancer initiation.

Somatic Genome-Engineered Mouse Models Using In Vivo Microinjection and Electroporation

This protocol describes microinjection and in vivo electroporation for regionally restricted CRISPR-mediated genome editing in the mouse oviduct.

Germline genetically engineered mouse models (G-GEMMs) have provided valuable insight into in vivo gene function in development, homeostasis, and disease. ...