We thank Harold Varmus, Brian C. Lewis, Douglas Hanahan, Danny Huang, Sharon Pang, Megan Wong, and Manasi M. Godbole. Y.C.N.D. is supported by DOD grant W81XWH-16-1-0619 and NIH grant 1R01CA204916.

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S., Varmus, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Receptor+for+hyaluronan-mediated+motility+isoform+B+promotes+liver+metastasis+in+a+mouse+model+of+multistep+tumorigenesis+and+a+tail+vein+assay+for+metastasis.">Receptor for hyaluronan-mediated motility isoform B promotes liver metastasis in a mouse model of multistep tumorigenesis and a tail vein assay for metastasis.</a> Proc Natl Acad Sci USA. 108 (40), 16753-16758 (2011).</li><li>Guernet, A., Grumolato, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR/Cas9+editing+of+the+genome+for+cancer+modeling.">CRISPR/Cas9 editing of the genome for cancer modeling.</a> Methods. , (2017).</li></ol>

The authors have nothing to disclose.

In this study, we described a powerful mouse model, RIP-Tag; RIP-tva, to achieve somatic gene delivery via avian retroviruses for the identification and characterization of metastatic factors. Although RIP-Tag; RIP-tva mice develop pancreatic neuroendocrine tumors, metastatic factors identified in this mouse model may also promote metastasis of other cancer types.
Our approach has the advantage of introducing somatic genetic changes specifically into premalignant lesions of pancreatic &#946; cells in a time-control manner, thus more faithfully mimicking sporadic human tumor development. This approach avoids any potential perturbation of normal tissue formation, which is often observed in conventional transgenic models due to the ectopic expression of the gene of interest during development. Furthermore, it is much faster to generate avian retroviral vectors carrying genes of interest than to generate transgenic mice. RCASBP-derived avian retroviral vector can deliver cDNAs (&#8804;2.5 kb), shRNAs, miRNAs, and other noncoding RNAs to tva-expressing cells in vitro and in vivo. The efficiency of infection (and multiple infection) is dependent on the proliferation rate of target cells and the accessibility of the cells. A titer of &#62;1 x 108 infectious units per ml is required for in vivo infection. More efficient viral delivery can be achieved in vitro due to induced cell proliferation and the possibility of repetitive exposure of all cells to viruses.
Precise intracardiac injection technique is critical for the viability of mice. First, a 50 &#181;l of air space in an insulin syringe before drawing up viral suspension is crucial for seeing cardiac pulse. Second, it is important to fix the position of syringe once a red pulse of blood appears, and to slowly deliver 10-20 &#181;l viral suspension whenever seeing a bright red pulse of blood appear in the syringe. If bright red pulses of blood stop after the delivery of 10-20 &#181;l viral suspension, slightly repositioning the needle will help. Third, after the last push of the plunger to deliver viral suspension and before seeing the blood pulse, the needle needs to be quickly retracted out of the chest cavity and a gentle pressure applied over the injection site will help to reduce internal bleeding. Last but not least, do not re-use the insulin syringe on another mouse.
For future applications, this RIP-Tag; RIP-tva mouse model can be combined with other transgenic, knock-in, and knockout mouse models. Moreover, we envision combining this RIP-Tag; RIP-tva mouse model with CRISPR-Cas9 genome-editing tool to generate single point mutations, deletion, genomic rearrangements such as inversions and translocations 22.

Most cancers arise from somatic mutations 1. Conventional genetically engineered mouse models (GEMM) have provided significant insights into the contribution of specific genetic alterations to tumorigenesis 2. However, they have several limitations. The major drawback of these models is that they do not replicate the sporadic nature of tumor formation in humans, in which only some cells within a tissue acquire genetic alterations. The mutations in transgenic and knockout mice are also germline with potential to affect development. Moreover, generating these mouse models is expensive and time-consuming.
Metastasis is a significant issue in the field of cancer. Modeling metastasis has been difficult in GEMM. Spontaneous metastasis is rare in the mouse. Penetrance is variable and latency is long in GEMM of metastasis 3. Experimental metastasis models employ direct injection of cells into the circulation of mice, so the early steps in the metastatic cascade are eliminated.
To overcome some of the above limitations in studying metastatic factors in mouse models, we have developed a bitransgenic mouse model, RIP-Tag; RIP-tva4. The strategy is based on combining the use of a highly-synchronized tumor progression mouse model, RIP-Tag 5, and the receptor for subgroup-A avian leukosis virus, tva 6,7. This RIP-Tag; RIP-tvamouse model allows genes to be introduced somatically into a single bitransgenic mouse strain. With the SV40 T antigen suppressing the tumor suppressive functions of Rb and p53, mice develop pancreatic neuroendocrine tumors in a similar fashion to human tumorigenesis, with stages including hyperplasia, angiogenesis, adenoma, and invasive carcinoma.This RIP-Tag model has been very instructive for our understanding of hallmarks of cancer, not limited to pancreatic neuroendocrine tumors. It has also been used in preclinical trials 8.
We present a protocol for somatic gene transfer through injection of avian retroviruses intracardiacally into RIP-Tag; RIP-tva mice. Successful infection with RCASBP-derived avian retroviruses requires actively proliferating target cells. Therefore, we chose RIP-Tag; RIP-tva mice at 7 weeks of age, when hyperplasia develops in about 50% of the pancreatic islets. Left ventricular intracardiac injection of high titer viruses is required to achieve an infection efficiency of 10-20% 4. This delivery method reduces the significant dilution of viral particles within circulation before viruses reach pancreatic islets.
Using this approach, we have previously demonstrated that Bcl-xL promotes cancer metastasis independent of its anti-apoptotic function 4,9. This anti-apoptotic-independent metastatic function was not observed when Bcl-xL was expressed via a transgene in all pancreatic &#946; cells throughout tumorigenic ontogeny in the RIP-Tag; RIP-Bcl-xL mouse model 10. Therefore, our mouse model offers a unique opportunity to identify and characterize genes&#39; functions when expressed at a later stage of tumorigenesis. Because 2-4% of islets develop into tumors in the RIP-Tag; RIP-tva bitransgenic mice without viral infection and not all the premalignant lesions are infected with the RCASBP-derived avian retroviruses, only the factors that confer a selective advantage over the natural course of tumorigenesis can be identified. In particular, metastatic factors will be most easily recognized by this method, because metastasis to pancreatic lymph nodes or other organs does not normally occur in RIP-Tag; RIP-tva mice.

<table border="0" cellpadding="0" cellspacing="0" width="747">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:339px;">RCASBP-Y DV plasmid</td>
			<td style="width:123px;">Addgene</td>
			<td style="width:119px;">11478</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RCAS-RNAi plasmid</td>
			<td style="width:123px;">Addgene</td>
			<td style="width:119px;">15182</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM</td>
			<td style="width:123px;">Corning</td>
			<td>10-013-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">fetal bovine serum</td>
			<td>Atlanta Biologicals</td>
			<td>25-005-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">L-glutamine, 100x</td>
			<td style="width:123px;">Corning</td>
			<td>25-005-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin-Streptomycin solution, 100x</td>
			<td style="width:123px;">Corning</td>
			<td>30-002-CI</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">PBS-/-, 1X</td>
			<td style="width:123px;">Corning</td>
			<td>21-040-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Superfect</td>
			<td>Qiagen</td>
			<td>301305</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Polyallomer centrifuge tube</td>
			<td>Beckman Coulter</td>
			<td>326823</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:339px;">0.45 mm Nalgene 
			Syringe Filters with PES Membrane</td>
			<td style="width:123px;">Thermo Scientific</td>
			<td style="width:119px;">194-2545</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:339px;">Insulin Syringes&#160;</td>
			<td style="width:123px;">BD</td>
			<td>329461</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">synaptophysin</td>
			<td style="width:123px;">Vector Laboratories</td>
			<td>VP-S284</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">VECTASTAIN Elite ABC HRP Kit (Peroxidase, Rabbit IgG)&#160;</td>
			<td style="width:123px;">Vector Laboratories</td>
			<td>PK-6101</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">AmpliTaq DNA Polymerase with Buffer II</td>
			<td>Life Technologies</td>
			<td>N8080153</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MyTaq DNA Polymerase</td>
			<td>Bioline</td>
			<td>BIO-21106</td>
			<td></td>
		</tr>
	</tbody>
</table>

identification and characterization of metastatic factors by gene transfer into the novel rip-tag; rip-tva murine model

Metastatic cancer accounts for 90% of deaths in patients with solid tumors. There is an urgent need to better understand the drivers of cancer metastasis and to identify novel therapeutic targets. To investigate molecular events that drive the progression from primary cancer to metastasis, we have developed a bitransgenic mouse model, RIP-Tag; RIP-tva. In this mouse model, the rat insulin promoter (RIP) drives the expression of the SV40 T antigen (Tag) and the receptor for subgroup A avian leukosis virus (tva) in pancreatic &#946; cells. The mice develop pancreatic neuroendocrine tumors with 100% penetrance through well-defined stages that are similar to human tumorigenesis, with stages including hyperplasia, angiogenesis, adenoma, and invasive carcinoma. Because RIP-Tag; RIP-tva mice do not develop metastatic disease, genetic alterations that promote metastasis can be identified easily. Somatic gene transfer into tva-expressing, proliferating pancreatic &#946; premalignant lesions is achieved through intracardiac injection of avian retroviruses harboring the desired genetic alteration. A titer of &#62;1 x 108 infectious units per ml is considered appropriate for in vivo infection. In addition, avian retroviruses can infect cell lines derived from tumors in RIP-Tag; RIP-tva mice with high efficiency. The cell lines can also be used to characterize the metastatic factors. Here we demonstrate how to utilize this mouse model and cell lines to assess the functions of candidate genes in tumor metastasis.

The in vivo and in vitro infection rate of RIP-Tag; RIP-tva tumor cells by RCASBP-based viruses are ~20% and ~80% respectively 20. In the RIP-Tag; RIP-tva mouse model, approximately 4% of the 400 pancreatic islets in each mouse will naturally develop into tumors 20; therefore there is sufficient amount of tumor cells in each mouse for histological and phenotypic analysis of the potential effect of the genes delivered by the viruses. Using this system, a novel nuclear function of Bcl-xL in metastasis was identified 9. RIP-Tag; RIP-tva mice infected with RCASBP-Bcl-xL exhibited a higher incidence of invasive carcinomas than mice infected with control viruses, RCASBP-ALPP (96% vs. 74%). Furthermore, 47% of RCASBP-Bcl-xL-infected RIP-Tag; RIP-tva mice developed metastases in pancreatic lymph nodes when euthanized at 16 weeks of age (Figure 3A), while no metastasis was found in control mice 20.
Moreover, we screened a library of cancer genes in RIP-Tag; RIP-tva mice, and identified the first gene that promotes metastasis to pancreatic lymph nodes and the liver 21 (Figure 3B and 3C). This gene encodes the Receptor for hyaluronan-mediated motility isoform B (RHAMMB) protein and activates EGFR signaling 21. We demonstrated that liver-specific metastasis can be recapitulated in a tail vein assay of experimental metastasis in which N134 tumor cells initially circulated through the lung capillary beds of the recipient immunodeficient mice 21.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55890/55890fig1.jpg" /> 
Figure 1: Schematic of RCASBP(A), RCAS-X, and RCAS-Y constructs. Cloning sites are indicated in blue, bold font. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55890/55890fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/55890/55890fig2.jpg" /> 
Figure 2: Placement of intracardiac injection. Anatomical landmarks are shown with horizontal dashed lines on the sternum (outlined in white). On the mouse&#39;s skin, the sternal notch and xyphoid process serve as landmarks, and the needle is inserted 1 mm away from the mid-sternum and slightly left (anatomical) of the sternum. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55890/55890fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/55890/55890fig3.jpg" /> 
Figure 3: Detection of metastatic pancreatic &#946; cells by immunostaining. Photographs show representative synaptophysin staining of metastatic pancreatic neuroendocrine tumors in pancreatic lymph nodes (A, B) or in the liver (C). RIP-Tag; RIP-tva mice were infected with the indicated RCASBP retroviruses at 7 weeks of age and euthanized at 16 weeks of age. Scale bar = 50 &#181;m. Original magnification = 20X. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55890/55890fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Identification and Characterization of Metastatic Factors by Gene Transfer into the Novel RIP-Tag; RIP-tva Murine Model at JoVE.com

Identification and Characterization of Metastatic Factors by Gene Transfer into the Novel RIP-Tag; RIP-tva Murine Model

We present a protocol to demonstrate a novel somatic gene transfer system utilizing RIP-Tag; RIP-tva mouse model to study the function of genes in metastasis. The avian retroviruses are delivered intracardiacally to ensure gene transfer into pre-malignant, noninvasive lesions of pancreatic &#946; cells in adult mice.

Identification and Characterization of Metastatic Factors by Gene Transfer into the Novel RIP-Tag; RIP-tva Murine Model

Metastatic cancer accounts for 90% of deaths in patients with solid tumors. There is an urgent need to better understand the drivers of cancer metastasis ...

identification-characterization-metastatic-factors-gene-transfer-into

Nanyang Technological University

Research

JoVE Journal

Cancer Research

8.7K Views.  Weill Cornell Medicine. We present a protocol to demonstrate a novel somatic gene transfer system utilizing RIP-Tag; RIP-tva mouse model to study the function of genes in metastasis. The avian retroviruses are delivered intracardiacally to ensure gene transfer into pre-malignant, noninvasive lesions of pancreatic β cells in adult mice.

Video: Identification and Characterization of Metastatic Factors by Gene Transfer into the Novel RIP-Tag; RIP-tva Murine Model

Advanced Animal Model of Colorectal Metastasis in Liver: Imaging Techniques and Properties of Metastatic Clones

Patients with a limited number of hepatic metastases and slow rates of progression can be successfully treated with local treatment approaches1,2. However, little is known about the heterogeneity of liver metastases, and animal models capable of evaluating the development of individual metastatic colonies are needed. Here, we present an advanced model of hepatic metastases that provides the ability to quantitatively visualize the development of individual tumor clones in the liver and estimate their growth kinetics and colonization efficiency. We generated a panel of monoclonal derivatives of HCT116 human colorectal cancer cells stably labeled with luciferase and tdTomato and possessing different growth properties. With a splenic injection followed by a splenectomy, the majority of these clones are able to generate hepatic metastases, but with different frequencies of colonization and varying growth rates. Using the In Vivo&#160;Imaging System (IVIS), it is possible to visualize and quantify metastasis development with in vivo luminescent and ex vivo fluorescent imaging. In addition, Diffuse Luminescent Imaging Tomography (DLIT) provides a 3D distribution of liver metastases in vivo. Ex vivo fluorescent imaging of harvested livers provides quantitative measurements of individual hepatic metastatic colonies, allowing for the evaluation of the frequency of liver colonization and the growth kinetics of metastases. Since the model is similar to clinically observed liver metastases, it can serve as a modality for detecting genes associated with liver metastasis and for testing potential ablative or adjuvant treatments for liver metastatic disease.

The ability of metastatic clones to colonize distant sites depends on their proliferation capacity and/or their ability to survive in the host microenvironment without significant proliferation. Here, we present an animal model that allows quantitative visualization of both types of liver colonization by metastatic clones.

Patients with a limited number of hepatic metastases and slow rates of progression can be successfully treated with local treatment approaches1,2. ...

A Syngeneic Mouse Model of Metastatic Renal Cell Carcinoma for Quantitative and Longitudinal Assessment of Preclinical Therapies

Renal cell carcinoma (RCC) affects &#62; 60,000 people in the United States annually, and ~ 30% of RCC patients have multiple metastases at the time of diagnosis. Metastatic RCC (mRCC) is incurable, with a median survival time of only 18 months. Immune-based interventions (e.g., interferon (IFN) and interleukin (IL)-2) induce durable responses in a fraction of mRCC patients, and multikinase inhibitors (e.g., sunitinib or sorafenib) or anti-VEGF receptor monoclonal antibodies (mAb) are largely palliative, as complete remissions are rare. Such shortcomings in current therapies for mRCC patients provide the rationale for the development of novel treatment protocols. A key component in the preclinical testing of new therapies for mRCC is a suitable animal model. Beneficial features that recapitulate the human condition include a primary renal tumor, renal tumor metastases, and an intact immune system to investigate any therapy-driven immune effector responses and the formation of tumor-induced immunosuppressive factors. This report describes an orthotopic mRCC mouse model that has all of these features. We describe an intrarenal implantation technique using the mouse renal adenocarcinoma cell line Renca, followed by the assessment of tumor growth in the kidney (primary site) and lungs (metastatic site).

Implementation of an orthotopic model of renal cell carcinoma in immunocompetent mice affords the investigator a clinically-relevant system defined by the presence of a primary renal tumor and lung metastases in the same animal. This system can be used to preclinically test a variety of treatments in vivo.

Renal cell carcinoma (RCC) affects &#62; 60,000 people in the United States annually, and ~ 30% of RCC patients have multiple metastases at the time of ...

A Mouse Model of Fatigue Induced by Peripheral Irradiation

Cancer-related fatigue (CRF) is a distressing and costly condition that often affects patients receiving cancer treatments, including radiation therapy. Here we describe a method using targeted peripheral irradiation to induce fatigue-like behavior in mice. With appropriate shielding, the irradiation targets the lower abdominal/pelvic region of the mouse, sparing the brain, in an effort to model radiation treatment received by individuals with pelvic cancers. We deliver an irradiation dose that is sufficient to induce fatigue-like behavior in mice, measured by voluntary wheel-running activity (VWRA), without causing obvious morbidity. Since wheel running is a normal, voluntary behavior in mice, its use should have little confounding effect on other behavioral tests or biological measures. Hence, wheel running can be used as a feasible outcome measure in understanding the behavioral and biological correlates of fatigue. CRF is a complex condition with frequent comorbidities, and likely has causes related both to cancer and its various treatments. The methods described in this paper are useful for investigating radiation-induced changes that contribute to the development of CRF and, more generally, to explore the biological networks that can explain the development and persistence of a peripherally-triggered but centrally-driven behavior like fatigue.

We describe a method using targeted peripheral irradiation to induce fatigue-like behavior in mice. The selected non-lethal irradiation dose leads to a week-long reduction in voluntary wheel-running activity.

Cancer-related fatigue (CRF) is a distressing and costly condition that often affects patients receiving cancer treatments, including radiation therapy. ...

Fabrication of Tongue Extracellular Matrix and Reconstitution of Tongue Squamous Cell Carcinoma In Vitro

In order to construct an effective and realistic model for tongue squamous cell carcinoma (TSCC) in vitro, the methods were created to produce decellularized tongue extracellular matrix (TEM) which provides functional scaffolds for TSCC construction. TEM provides an in vitro niche for cell growth, differentiation, and cell migration. The microstructures of native extracellular matrix (ECM) and biochemical compositions retained in the decellularized matrix provide tissue-specific niches for anchoring cells. The fabrication of TEM can be realized by deoxyribonuclease (DNase) digestion accompanied with a serious of organic or inorganic pretreatment. This protocol is easy to operate and ensures high efficiency for the decellularization. The TEM showed favorable cytocompatibility for TSCC cells under static or stirred culture conditions, which enables the construction of the TSCC model. A self-made bioreactor was also used for the persistent stirred condition for cell culture. Reconstructed TSCC using TEM showed the characteristics and properties resembling clinical TSCC histopathology, suggesting the potential in TSCC research.

Fabrication of Tongue Extracellular Matrix and Reconstitution of Tongue Squamous Cell Carcinoma In Vitro

A method is shown here for the preparation of the tongue extracellular matrix (TEM) with efficient decellularization. The TEM can be used as functional scaffolds for the reconstruction of a tongue squamous cell carcinoma (TSCC) model under static or stirred culture conditions.

In order to construct an effective and realistic model for tongue squamous cell carcinoma (TSCC) in vitro, the methods were created to produce ...

A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer

Orthotopic tumor modeling is a valuable tool for pre-clinical prostate cancer research, as it has multiple advantages over both subcutaneous and transgenic genetically engineered mouse models. Unlike subcutaneous tumors, orthotopic tumors contain more clinically accurate vasculature, tumor microenvironment, and responses to multiple therapies. In contrast to genetically engineered mouse models, orthotopic models can be performed with lower cost and in less time, involve the use of highly complex and heterogeneous mouse or human cancer cell lines, rather that single genetic alterations, and these cell lines can be genetically modified, such as to express imaging agents. Here, we present a protocol to surgically injecting a luciferase- and mCherry-expressing murine prostate cancer cell line into the anterior prostate lobe of mice. These mice developed orthotopic tumors that were non-invasively monitored in vivo and further analyzed for tumor volume, weight, mouse survival, and immune infiltration. Further, orthotopic tumor-bearing mice were surgically castrated, leading to immediate tumor regression and subsequent recurrence, representing castration-resistant prostate cancer. Although technical skill is required to carry out this procedure, this syngeneic orthotopic model of both androgen-dependent and castration-resistant prostate cancer is of great use to all investigators in the field.

The goal of this protocol is to demonstrate the intra-prostatic injection of prostate cancer cells, with subsequent castration. Orthotopic pre-clinical models of androgen-dependent and castration-resistant prostate cancer are critical to study the disease in the context of a clinically relevant tumor microenvironment and an immunocompetent host.

Orthotopic tumor modeling is a valuable tool for pre-clinical prostate cancer research, as it has multiple advantages over both subcutaneous and ...

Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration

With an increasing incidence of prostate cancer, identification of new tumor drivers or modulators is crucial. Genetically engineered mouse models (GEMM) for prostate cancer are hampered by tumor heterogeneity and its complex microevolution dynamics. Traditional prostate cancer mouse models include, amongst others, germline and conditional knockouts, transgenic expression of oncogenes, and xenograft models. Generation of de novo mutations in these models is complex, time-consuming, and costly. In addition, most of traditional models target the majority of the prostate epithelium, whereas human prostate cancer is well known to evolve as an isolated event in only a small subset of cells. Valuable models need to simulate not only prostate cancer initiation, but also progression to advanced disease.
Here we describe a method to target a few cells in the prostate epithelium by transducing cells by viral particles. The delivery of an engineered virus to the murine prostate allows alteration of gene expression in the prostate epithelia. Virus type and quantity will hereby define the number of targeted cells for gene alteration by transducing a few cells for cancer initiation and many cells for gene therapy. Through surgery-based injection in the anterior lobe, distal from the urinary track, the tumor in this model can expand without impairing the urinary function of the animal. Furthermore, by targeting only a subset of prostate epithelial cells the technique enables clonal expansion of the tumor, and therefore mimics human tumor initiation, progression, as well as invasion through the basal membrane.
This novel technique provides a powerful prostate cancer model with improved physiological relevance. Animal suffering is limited, and since no additional breeding is required, overall animal count is reduced. At the same time, analysis of new candidate genes and pathways is accelerated, which in turn is more cost efficient.

This protocol describes a newly established method for virus delivery to the murine prostate. Using either CRISPR/Cas9 technology, gene overexpression, or Cre recombinase delivery, the technique allows orthotopic alteration of gene expression and implements a novel mouse model for prostate cancer.

With an increasing incidence of prostate cancer, identification of new tumor drivers or modulators is crucial. Genetically engineered mouse models (GEMM) ...

Enrichment and Characterization of the Tumor Immune and Non-immune Microenvironments in Established Subcutaneous Murine Tumors

The tumor immune microenvironment (TIME) has recently been recognized as a critical mediator of treatment response in solid tumors, especially for immunotherapies. Recent clinical advances in immunotherapy highlight the need for reproducible methods to accurately and thoroughly characterize the tumor and its associated immune infiltrate. Tumor enzymatic digestion and flow cytometric analysis allow broad characterization of numerous immune cell subsets and phenotypes; however, depth of analysis is often limited by fluorophore restrictions on panel design and the need to acquire large tumor samples to observe rare immune populations of interest. Thus, we have developed an effective and high throughput method for separating and enriching the tumor immune infiltrate from the non-immune tumor components. The described tumor digestion and centrifugal density-based separation technique allows separate characterization of tumor and tumor immune infiltrate fractions and preserves cellular viability, and thus, provides a broad characterization of the tumor immunologic state. This method was used to characterize the extensive spatial immune heterogeneity in solid tumors, which further demonstrates the need for consistent whole tumor immunologic profiling techniques. Overall, this method provides an effective and adaptable technique for the immunologic characterization of subcutaneous solid murine tumors; as such, this tool can be used to better characterize the tumoral immunologic features and in the preclinical evaluation of novel immunotherapeutic strategies.

Here we describe a method to separate and enrich components of the tumor immune and non-immune microenvironment in established subcutaneous tumors. This technique allows for the separate analysis of tumor immune infiltrate and non-immune tumor fractions which can permit comprehensive characterization of the tumor immune microenvironment.

The tumor immune microenvironment (TIME) has recently been recognized as a critical mediator of treatment response in solid tumors, especially for ...

Identification, Histological Characterization, and Dissection of Mouse Prostate Lobes for In Vitro 3D Spheroid Culture Models

Genetically engineered mouse models (GEMMs) serve as effective pre-clinical models for investigating most types of human cancers, including prostate cancer (PCa). Understanding the anatomy and histology of the mouse prostate is important for the efficient use and proper characterization of such animal models. The mouse prostate has four distinct pairs of lobes, each with their own characteristics. This article demonstrates the proper method of dissection and identification of mouse prostate lobes for disease analysis. Post-dissection, the prostate cells can be further cultured in vitro for mechanistic understanding. Since mouse prostate primary cells tend to lose their normal characteristics when cultured in vitro, we outline here a method for isolating the cells and growing them as 3D spheroid cultures, which is effective for preserving the physiological characteristics of the cells. These 3D cultures can be used for analyzing cell morphology and behavior in near-physiological conditions, investigating altered levels and localizations of key proteins and pathways involved in the development and progression of a disease, and looking at responses to drug treatments.

Genetically engineered mice are useful models for investigating prostate cancer mechanisms. Here we present a protocol to identify and dissect prostate lobes from a mouse urogenital system, differentiate them based on histology, and isolate and culture the primary prostate cells in vitro as spheroids for downstream analyses.

Genetically engineered mouse models (GEMMs) serve as effective pre-clinical models for investigating most types of human cancers, including prostate ...

Three-Dimensional Bone Extracellular Matrix Model for Osteosarcoma

Osteosarcoma (OS) is the most common and a highly aggressive primary bone tumor. It is characterized with anatomic and histologic variations along with diagnostic or prognostic difficulties. OS comprises genotypically and phenotypically heterogeneous cancer cells. Bone microenvironment elements are proved to account for tumor heterogeneity and disease progression. Bone extracellular matrix (BEM) retains the microstructural matrices and biochemical components of native extracellular matrix. This tissue-specific niche provides a favorable and long-term scaffold for OS cell seeding and proliferation. This article provides a protocol for the preparation of BEM model and its further experimental application. OS cells can grow and differentiate into multiple phenotypes consistent with the histopathological complexity of OS clinical specimens. The model also allows visualization of diverse morphologies and their association with genetic alterations and underlying regulatory mechanisms. As homologous to human OS, this BEM-OS model can be developed and applied to the pathology and clinical research of OS.

The bone extracellular matrix (BEM) model for osteosarcoma (OS) is well established and shown here. It can be used as a suitable scaffold for mimicking primary tumor growth in vitro and providing an ideal model for studying the histologic and cytogenic heterogeneity of OS.

Osteosarcoma (OS) is the most common and a highly aggressive primary bone tumor. It is characterized with anatomic and histologic variations along with ...

Murine Model of Metastatic Liver Tumors in the Setting of Ischemia Reperfusion Injury

Liver ischemia and reperfusion (I/R) injury, a common clinical challenge, remains an inevitable pathophysiological process that has been shown to induce multiple tissue and organ damage. Despite recent advances and therapeutic approaches, the overall morbidity has remained unsatisfactory especially in patients with underlying parenchymal abnormalities. In the context of aggressive cancer growth and metastasis, surgical I/R is suspected to be the promoter regulating tumor recurrence. This article aims to describe a clinically relevant murine model of liver I/R and colorectal liver metastasis. In doing so, we aim to assist other investigators in establishing and perfecting this model for their routine research practice to better understand the effects of liver I/R on promoting liver metastases.

We describe in detail a clinically relevant colorectal cancer liver metastases (CRLM) tumor model and the influence of liver ischemia reperfusion (I/R) in tumor growth and metastasis. This model can help to better understand the mechanisms underlying surgery-induced promotion of liver metastatic growth.

Liver ischemia and reperfusion (I/R) injury, a common clinical challenge, remains an inevitable pathophysiological process that has been shown to induce ...