Name: modeling breast cancer via an intraductal injection of cre-expressing adenovirus into the mouse mammary gland
Uploaded: 2019-06-07T13:30:00
Description: Watch this Scientific Journal Video about Modeling Breast Cancer via an Intraductal Injection of Cre-expressing Adenovirus into the Mouse Mammary Gland at JoVE.com

This work was supported by National Institutes of Health (NIH) grant R01 CA222560 and by Department of Defense Breakthrough Award W81XWH-18-1-0037.

All methods described here have been approved by the Institutional Animal Care and Use Committee (IACUC) of Brigham and Women&#8217;s Hospital.
1. Generation and maintenance of floxed mice
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	<li>Obtain breast cancer-relevant floxed conditional knockout (e.g., Trp53tm1Brn [referred to as Trp53L/L], Brca1tm1Aash [Brca1L/L]) or conditional knock-in mouse lines (e.g., Gt(ROSA)26Sortm1(Pik3ca*H1047R)Egan<...

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P., Li, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Long-Lived+Luminal+Subpopulation+Enriched+with+Alveolar+Progenitors+Serves+as+Cellular+Origin+of+Heterogeneous+Mammary+Tumors.">A Long-Lived Luminal Subpopulation Enriched with Alveolar Progenitors Serves as Cellular Origin of Heterogeneous Mammary Tumors.</a> Stem Cell Reports. 5 (1), 60-74 (2015).</li><li>Xu, X., 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=Conditional+mutation+of+Brca1+in+mammary+epithelial+cells+results+in+blunted+ductal+morphogenesis+and+tumour+formation.">Conditional mutation of Brca1 in mammary epithelial cells results in blunted ductal morphogenesis and tumour formation.</a> Nature Genetics. 22 (1), 37-43 (1999).</li><li>Li, Z., 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=ETV6-NTRK3+fusion+oncogene+initiates+breast+cancer+from+committed+mammary+progenitors+via+activation+of+AP1+complex.">ETV6-NTRK3 fusion oncogene initiates breast cancer from committed mammary progenitors via activation of AP1 complex.</a> Cancer Cell. 12 (6), 542-558 (2007).</li><li>Liu, X., 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=Somatic+loss+of+BRCA1+and+p53+in+mice+induces+mammary+tumors+with+features+of+human+BRCA1-mutated+basal-like+breast+cancer.">Somatic loss of BRCA1 and p53 in mice induces mammary tumors with features of human BRCA1-mutated basal-like breast cancer.</a> Proceedings of the National Academy of Sciences of the United States of America. 104 (29), 12111-12116 (2007).</li><li>Molyneux, G., 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=BRCA1+basal-like+breast+cancers+originate+from+luminal+epithelial+progenitors+and+not+from+basal+stem+cells.">BRCA1 basal-like breast cancers originate from luminal epithelial progenitors and not from basal stem cells.</a> Cell Stem Cell. 7 (3), 403-417 (2010).</li><li>Koren, S., 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=PIK3CA+induces+multipotency+and+multi-lineage+mammary+tumours.">PIK3CA induces multipotency and multi-lineage mammary tumours.</a> Nature. 525 (7567), 114-118 (2015).</li><li>Van Keymeulen, 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=Reactivation+of+multipotency+by+oncogenic+PIK3CA+induces+breast+tumour+heterogeneity.">Reactivation of multipotency by oncogenic PIK3CA induces breast tumour heterogeneity.</a> Nature. 525 (7567), 119-123 (2015).</li><li>Tao, L., Xiang, D., Xie, Y., Bronson, R. T., Li, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induced+p53+loss+in+mouse+luminal+cells+causes+clonal+expansion+and+development+of+mammary+tumours.">Induced p53 loss in mouse luminal cells causes clonal expansion and development of mammary tumours.</a> Nature Communications. 8, 14431 (2017).</li><li>Tao, L., van Bragt, M. P. A., Laudadio, E., Li, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lineage+Tracing+of+Mammary+Epithelial+Cells+Using+Cell-Type-Specific+Cre-Expressing+Adenoviruses.">Lineage Tracing of Mammary Epithelial Cells Using Cell-Type-Specific Cre-Expressing Adenoviruses.</a> Stem Cell Reports. 2 (6), 770-779 (2014).</li><li>Sutherland, K. D., 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=Cell+of+origin+of+small+cell+lung+cancer:+inactivation+of+Trp53+and+Rb1+in+distinct+cell+types+of+adult+mouse+lung.">Cell of origin of small cell lung cancer: inactivation of Trp53 and Rb1 in distinct cell types of adult mouse lung.</a> Cancer Cell. 19 (6), 754-764 (2011).</li><li>Shackleton, M., 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=Generation+of+a+functional+mammary+gland+from+a+single+stem+cell.">Generation of a functional mammary gland from a single stem cell.</a> Nature. 439 (7072), 84-88 (2006).</li><li>The Cancer Genome Atlas Network. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comprehensive+molecular+portraits+of+human+breast+tumours.">Comprehensive molecular portraits of human breast tumours.</a> Nature. 490 (7418), 61-70 (2012).</li><li>Nik-Zainal, S., 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=The+life+history+of+21+breast+cancers.">The life history of 21 breast cancers.</a> Cell. 149 (5), 994-1007 (2012).</li><li>Abba, M. C., 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+Molecular+Portrait+of+High-Grade+Ductal+Carcinoma+In+Situ.">A Molecular Portrait of High-Grade Ductal Carcinoma In Situ.</a> Cancer Research. 75 (18), 3980-3990 (2015).</li></ol>

The success of this approach for inducing mammary tumors from different subpopulations of MECs relies not only on choosing appropriate cell-type-specific promoters (to drive Cre expression) but also on the intraductal injection procedure itself. The idea behind this approach is that the injected Ad-Cre viruses are retained in the ductal tree, which is a concealed structure with lumen, and therefore, only MECs are exposed to the viruses and are infected by Ad-Cre. Due to the limited lumen space within the mammary ducts, i...

The overall goal of this method is to develop a new breast cancer modeling approach based on an intraductal injection of Ad-Cre into the mouse MG. The Cre/loxP recombination-based genetic approach has been widely used to model human breast cancer in mice. The first generation of Cre/loxP-based breast cancer mouse models are generated by using Cre-expressing transgenic mice under the control of MEC-specific promoters (e.g., MMTV-Cre for luminal MECs and a portion of basal MECs, Wap-Cre and Blg-Cre for luminal progenitors and alveolar luminal MECs, K14-Cre for basal and a portion of luminal MECs1,2,3,4,5)6,7,8,9. However, while these Cre transgenic lines enable spatial control of Cre expression (i.e., in different subsets of MECs), they do not allow temporal control of Cre expression and Cre/loxP-mediated genetic manipulation. The second generation of Cre/loxP-based breast cancer mouse models utilize inducible Cre activity/expression approaches (e.g., use of Cre-estrogen receptor fusion [CreER], which can only induce Cre/loxP recombination upon administration of tamoxifen), and as a result, these genetic tools permit both spatial and temporal controls of the activation of oncogenic events in MECs (e.g., K8-CreER- and K5-CreER-based models)10,11,12. In both generations of breast cancer mouse models, as promoters used to drive Cre or CreER expression (e.g., Krt8, Krt5) may also be active in epithelial cells of other organs (i.e., they are cell-type-specific but not organ-specific) or have a leaky expression in cell types other than epithelial cells (e.g., MMTV, which has leaky activity in bone marrow hematopoietic cells), these approaches may lead to the development of unwanted cancer(s) in other organ(s). If these unexpected cancers cause lethality in the affected mice, the original purpose of modeling breast cancer in these mice may be prohibited (e.g., MMTV-Cre-driven oncogenic events may lead to hematopoietic malignancies and early death of the mice, due to leakiness of the MMTV promoter in hematopoietic cells)4.
Here we report a breast cancer modeling approach in mice that allows both cell-type- and organ-specific manipulation of oncogenic events in a temporally controlled manner. This approach is based on an intraductal injection of Ad-Cre into mouse MGs (and is, thus, organ-specific). Cre expression can be controlled by using different MEC subpopulation-specific promoters embedded in the adenoviral vector (e.g., Krt8 for luminal MECs, Krt5 for basal MECs, thus achieving cell-type specificity). Cancer induction in MGs can be temporally controlled by an injection of Ad-Cre into mice at different ages, starting from 3-4 weeks of age (pubertal) to the adult stage.

<table>
	<tbody>
		<tr>
			<td>33-gauge needle</td>
			<td>Hamilton</td>
			<td>7803-05</td>
			<td>point style 3 blunt</td>
		</tr>
		<tr>
			<td>7mm Reflex Clip</td>
			<td>Braintree Scientific</td>
			<td>RF7 CS</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenovirus, Ad-K5-Cre</td>
			<td>University of Iowa Viral Vector Core</td>
			<td>Ad5-bk5-Cre (VVC-Berns-1547)</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenovirus, Ad-K8-Cre</td>
			<td>University of Iowa Viral Vector Core</td>
			<td>Ad5mK8-nlsCre</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol</td>
			<td>Fisher</td>
			<td>HC800-1GAL</td>
			<td>Prepare to 70% in use</td>
		</tr>
		<tr>
			<td>biotinylated CD31</td>
			<td>eBiosciences</td>
			<td>13-0311-85</td>
			<td></td>
		</tr>
		<tr>
			<td>biotinylated CD45</td>
			<td>eBiosciences</td>
			<td>13-0451-85</td>
			<td></td>
		</tr>
		<tr>
			<td>biotinylated TER119</td>
			<td>eBiosciences</td>
			<td>13-5921-85</td>
			<td></td>
		</tr>
		<tr>
			<td>Bromophenol Blue</td>
			<td>Sigma-Aldrich</td>
			<td>B0126-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>CD24-AF-700</td>
			<td>BD Pharmingen</td>
			<td>564237</td>
			<td></td>
		</tr>
		<tr>
			<td>CD24-PE</td>
			<td>eBiosciences</td>
			<td>12-0242-83</td>
			<td></td>
		</tr>
		<tr>
			<td>CD29-APC</td>
			<td>eBiosciences</td>
			<td>17-0291-82</td>
			<td></td>
		</tr>
		<tr>
			<td>CD29-PE</td>
			<td>eBiosciences</td>
			<td>12-0291-82</td>
			<td></td>
		</tr>
		<tr>
			<td>Hair Remover Lotion</td>
			<td>Nair</td>
			<td></td>
			<td>9 Oz</td>
		</tr>
		<tr>
			<td>Hamilton syringe</td>
			<td>Hamilton</td>
			<td>7636-01</td>
			<td>0.025 mL</td>
		</tr>
		<tr>
			<td>Iodophors</td>
			<td>Betadine</td>
			<td></td>
			<td>10% Povidone-iodine</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Baxter</td>
			<td>NDC 10019-360-40</td>
			<td>1-2.5%</td>
		</tr>
		<tr>
			<td>Loxicam</td>
			<td>Norbrook</td>
			<td>NDC 55529-040-10</td>
			<td>5 mg/ml</td>
		</tr>
		<tr>
			<td>Lubricant Eye Ointment</td>
			<td>Akorn</td>
			<td colspan="2">NDC 17478-062-35</td>
		</tr>
		<tr>
			<td>Micro-dissecting scissors</td>
			<td>Pentair</td>
			<td>9M</td>
			<td>Watchmaker&#39;s Forceps</td>
		</tr>
		<tr>
			<td>Micro-dissecting tweezers</td>
			<td>Dumont</td>
			<td>M5</td>
			<td></td>
		</tr>
		<tr>
			<td>Taq 5X Master Mix</td>
			<td>New England Biolabs</td>
			<td>M0285L</td>
			<td></td>
		</tr>
	</tbody>
</table>

modeling breast cancer via an intraductal injection of cre-expressing adenovirus into the mouse mammary gland

Breast cancer is a heterogeneous disease, possibly due to complex interactions between different cells of origins and oncogenic events. Mouse models are instrumental in gaining insights into these complex processes. Although many mouse models have been developed to study contributions of various oncogenic events and cells of origin to breast tumorigenesis, these models are often not cell-type or organ specific or cannot induce the initiation of mammary tumorigenesis in a temporally controlled manner. Here we describe a protocol to generate a new type of breast cancer mouse models based on the intraductal injection of Cre-expressing adenovirus (Ad-Cre) into mouse mammary glands (MGs). Due to the direct injection of Ad-Cre into mammary ducts, this approach is MG specific, without any unwanted cancer induction in other organs. The intraductal injection procedure can be performed in mice at different stages of their MG development (thus, it permits temporal control of cancer induction, starting from ~3-4 weeks of age). The cell-type specificity can be achieved by using different cell-type-specific promoters to drive Cre expression in the adenoviral vector. We show that luminal and basal mammary epithelial cells (MECs) can be tightly targeted for Cre/loxP-based genetic manipulation via an intraductal injection of Ad-Cre under the control of the Keratin 8 or Keratin 5 promoter, respectively. By incorporating a conditional Cre reporter (e.g., Cre/loxP-inducible Rosa26-YFP reporter), we show that MECs targeted by Ad-Cre, and tumor cells derived from them, can be traced by following the reporter-positive cells after intraductal injection.

Representative PCR genotyping results for the R26Y and Trp53L alleles are shown in Figure 1.
Although, in principle, all 10 MGs can be subjected to the intraductal injection procedure, practically, the two fourth inguinal MGs are typically selected for injection, due to their easier accessibility and larger MG sizes (Figure 2). During the su...

Watch this Scientific Journal Video about Modeling Breast Cancer via an Intraductal Injection of Cre-expressing Adenovirus into the Mouse Mammary Gland at JoVE.com

Modeling Breast Cancer via an Intraductal Injection of Cre-expressing Adenovirus into the Mouse Mammary Gland

The goal of this protocol is to describe a new breast cancer modeling approach based on the intraductal injection of Cre-expressing adenovirus into mouse mammary glands. This approach allows both cell-type- and organ-specific manipulation of oncogenic events in a temporally controlled manner.

Breast cancer is a heterogeneous disease, possibly due to complex interactions between different cells of origins and oncogenic events. Mouse models are ...

This protocol will help researchers generate a new type of mouse model to recapitulate human breast cancer development from different subsets of mammary epithelial cells. This technique allows researchers to generate breast cancer mouse models in developmental stage tissue on a cell type specific manner and without a need for extensive mouse breeding. To begin this procedure, generate, maintain, and anesthetize floxed mice as described in the text protocol.Bring the mouse to an area separate from where the surgery is to be performed. After confirming anesthesia by performing a toe pinch, inject Meloxicam as analgesia subcutaneously at a dose of five milligrams per kilogram to prepare for the surgical procedure. Expose the nipple surgical site by applying several drops of hair removal cream.Remove excessive cream and loose hair using soft paper towels. Shaving is not recommended to avoid damage to the nipples. Disinfect the surgical site with iodophors first followed by 70%alcohol and end with a final application of scrub iodophors.Do this in a circular motion from the center of the work area toward the periphery using a gauze sponge or a cotton-tipped applicator. Repeat the cycle three to four times. Use aseptic techniques throughout the surgical procedure.Make an incision site on the skin at a length of approximately one centimeter between the two fourth inguinal mammary glands. Carefully separate the skin flap from the parietal peritoneum so as to visual the mammary ductal tree. Carefully hold the nipple with watchmakers'forceps to remove the exterior nipple without cutting any nearby skin using a microdissection scissor.Load approximately three to five microliters of Cre-adenovirus injection mixture into a 25 microliter Hamilton syringe with a 33 gauge metal hub needle affixed. Estimate the volume of the injection mixture in the syringe based on the blue dye included in the mixture. Gently hold the edge of the skin flap with a fine curved tweezer and inject the Cre-adenovirus injection mixture slowly into the nipple while monitoring the spreading of blue dye into the mammary ductal tree.Maintain the injection rate at slow as possible to avoid damage to the ductal lumen. A successful intraductal injection is indicated by injected fluids spreading throughout the entire ductal tree without leaking into the stroma compartment. Gently withdraw the needle from the nipple to avoid any leakage of the injected fluid.Examine the distal side of the mammary gland or the surrounding area of the injected nipple. Dye diffusing into the nearby stroma as shown here indicates a mammary fat pad injection rather than a successful intraductal injection. Close the surgical wounds in the skin with wound clips.Remove the mouse from the anesthesia and place it on a heating pad inside a clean cage for recovery. Monitor the development of the mammary tumor as described in the text protocol. The youngest female mice for which intraductal injection can be successfully performed are those at approximately three weeks of age.Although for most mammary tumor induction experiments, young adult female mice are used. Intraductal injection with a larger volume of the injection mixture can be performed in female mice during early to mid gestation to target alveolar cells. To target different mammary epithelial cell subpopulations for mammary tumor induction, Cre-adenoviruses under the control of different mammary epithelial cell subset specific promoters were used for injection.For example Cre-adenovirus under the control of keratin 8 promoter was used to target luminal mammary epithelial cells. Cre-adenovirus under the control of keratin 5 promoter targeted the basal lineage leading to genetic marking of only basal mammary epithelial cells. For a female P53 floxed homozygous mice with a ROSA26-YFP reporter, the intraductal injection of keratin 8 Cre-adenovirus led to the development of mammary tumors several months after the injection.Due to the inclusion of the conditional R26-Y reporter, tumor epithelial cells were typically marked by YFP and could be detected by flow cytometry. The cells can be enriched by the flow sorting of YFP positive cells for further analysis. The most important things to remember when attempting this procedure are to use a small injection volume, inject slowly, and also withdraw the needle slowly.Following this procedure, one can monitor progression of the targeted YFP positive mammary epithelial cells to pre-malignant and cancer stages by flow cytometry or co-immunofluorescence staining of the injected gland. This technique will pave the way for researchers to study cells of origin of breast cancer, how they respond to different autogenic events and how they progress to cancer cells. Both adenovirus and the needle for injection are potentially hazardous.Therefore, one should always wear gloves and use safety needles and syringes when performing intraductal injection.

modeling-breast-cancer-via-an-intraductal-injection-cre-expressing

Research

JoVE Journal

Cancer Research

Intra-iliac Artery Injection for Efficient and Selective Modeling of Microscopic Bone Metastasis

Intra-iliac artery (IIA) injection is an efficient approach to introduce metastatic lesions of various cancer cells in animals. Compared to the widely used intra-cardiac and intra-tibial injections, IIA injection brings several advantages. First, it can deliver a large quantity of cancer cells specifically to hind limb bones, thereby providing spatiotemporally synchronized early-stage colonization events and allowing robust quantification and swift detection of disseminated tumor cells. Second, it injects cancer cells into the circulation without damaging the local tissues, thereby avoiding inflammatory and wound-healing processes that confound the bone colonization process. Third, IIA injection causes very little metastatic growth in non-bone organs, thereby preventing animals from succumbing to other vital metastases, and allowing continuous monitoring of indolent bone lesions. These advantages are especially useful for the inspection of progression from single cancer cells to multi-cell micrometastases, which has largely been elusive in the past. When combined with cutting-edge approaches of biological imaging and bone histology, IIA injection can be applied to various research purposes related to bone metastases.

This manuscript provides the detailed procedure of intra-iliac artery (IIA) injection, a technique to deliver cancer cells specifically to hind limb tissues including bones to establish experimental bone metastases. Although initially established with breast tumor models, this protocol can be easily extended to other cancer types.

Intra-iliac artery (IIA) injection is an efficient approach to introduce metastatic lesions of various cancer cells in animals. Compared to the widely ...

Utilizing Functional Genomics Screening to Identify Potentially Novel Drug Targets in Cancer Cell Spheroid Cultures

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery of the next generation of novel drug targets. It is becoming apparent that more complex models of cancer are required to fully appreciate the contributing factors that drive tumorigenesis in vivo and increase the efficacy of novel therapies that make the transition from pre-clinical models to clinical trials.
Here we present a methodology for generating uniform and reproducible tumor spheroids that can be subjected to siRNA functional screening. These spheroids display many characteristics that are found in solid tumors that are not present in traditional two-dimension culture. We show that several commonly used breast cancer cell lines are amenable to this protocol. Furthermore, we provide proof-of-principle data utilizing the breast cancer cell line BT474, confirming their dependency on amplification of the epidermal growth factor receptor HER2 and mutation of phosphatidylinositol-4,5-biphosphate 3-kinase (PIK3CA) when grown as tumor spheroids. Finally, we are able to further investigate and confirm the spatial impact of these dependencies using immunohistochemistry.

Identifying novel drug targets that transition from pre-clinical testing to human trials is a scientific priority. To that end, here we describe a functional genomics approach for examining the impact of gene depletion on cancer cell line spheroids, which more appropriately model human cancers in vivo.

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery ...

Intracarotid Cancer Cell Injection to Produce Mouse Models of Brain Metastasis

Metastasis, the spread and growth of malignant cells at secondary sites within a patient&#39;s body, accounts for &#62; 90% of cancer-related mortality. Recently, impressive advances in novel therapies have dramatically prolonged survival and improved quality of life for many cancer patients. Sadly, incidence of brain metastatic recurrences is fast rising, and all current therapies are merely palliative. Hence, good experimental animal models are urgently needed to facilitate in-depth studies of the disease biology and to assess novel therapeutic regimens for preclinical evaluation. However, the standard in vivo metastasis assay via tail vein injection of cancer cells produces predominantly lung metastatic lesions; animals usually succumb to the lung tumor burden before any meaningful outgrowth of brain metastasis. Intracardiac injection of tumor cells produces metastatic lesions to multiple organ sites including the brain; however, the variability of tumor growth produced with this model is large, dampening its utility in evaluating therapeutic efficacy. To generate reliable and consistent animal models for brain metastasis study, here we describe a procedure for producing experimental brain metastasis in the house mouse (Mus musculus) via intracarotid injection of tumor cells. This approach allows one to produce large number of brain metastasis-bearing mice with similar growth and mortality characteristics, thus facilitating research efforts to study basic biological mechanisms and to assess novel therapeutic agents.

Brain metastasis has become an urgent unmet medical need as its incidence has increased while therapeutic options have remained palliative. Creating experimental animal models of brain metastasis via intracarotid arterial injection of cancer cells facilitates mechanistic studies of the disease biology and evaluation of novel intervention regimens.

Metastasis, the spread and growth of malignant cells at secondary sites within a patient&#39;s body, accounts for &#62; 90% of cancer-related mortality. ...

Sectioning Mammary Gland Whole Mounts for Lesion Identification

Normal mammary gland development may be altered by exposure to environmental toxicants and pharmaceutical products, excessive exposure to hormones, and genetic alterations. Mammary gland whole mounts are an inexpensive method to capture the progression of morphological changes that may arise after exposure. However, in later life, when abnormalities are more prone to develop, sole reliance on this one method may not always provide enough information to make a proper diagnosis of the abnormality. Historically, in chemical test guideline studies, a single mammary gland is removed at necropsy and prepared as a hematoxylin and eosin (H&#38;E)-stained section. The incorporation of contralateral mammary whole-mount collection and analysis decreases the likelihood of a false-negative assessment. Evaluation of the whole mount is limited by the presence of one or two entire mammary glands on a slide, and in some cases, the abnormalities observed in the whole mount are not uniformly represented in the H&#38;E section.&#160; The goal of this study was to develop a protocol for converting coverslipped mammary whole mounts to H&#38;E-stained sections so that lesions that would otherwise have been missed or that are difficult to diagnose can be identified. Here, we detail a method to produce a high-quality, paraffin-embedded H&#38;E section from a mammary gland that was initially prepared as a whole mount. In comparison to a tissue that was intentionally prepared for H&#38;E sectioning, the whole mount requires additional preparation for tissue removal and processing. However, this method is considered inexpensive, as it requires common lab reagents and little additional time. As a result, this method can provide invaluable information on how chemical and environmental exposures alter normal mammary development, as well as display changes that occur because of genetic modifications.

We developed a method to successfully remove, process, section, and stain, for histopathological evaluation, mammary tissue that had originally been fixed on slides as whole mounts. This method may promote the collection and evaluation of mammary gland whole mounts in reproductive and developmental test guideline studies.

Normal mammary gland development may be altered by exposure to environmental toxicants and pharmaceutical products, excessive exposure to hormones, and ...

Orthotopic Injection of Breast Cancer Cells into the Mice Mammary Fat Pad

A proper animal model is crucial for a better understanding of diseases. Animal models established by different methods (subcutaneous injections, xenografts, genetic manipulation, chemical reagents induction, etc.) have various pathological characters and play important roles in investigating certain aspects of diseases. Although no single model can totally mimic the whole human disease progression, orthotopic organs disease models with a proper stromal environment play an irreplaceable role in understanding diseases and screening for potential drugs. In this article, we describe how to implant breast cancer cells into the mammary fat pad in a simple, less invasive, and easy-to-handle way, and follow the metastasis to distant organs. With the proper features of primary tumor growth, breast and nipple pathological changes, and a high occurrence of other organs&#39; metastasis, this model maximumly mimics human breast cancer progression. Primary tumor growth in situ, long-distant metastasis, and the tumor microenvironment of breast cancer can be investigated by using this model.

Here, we present a protocol to implant breast cancer cells into the mammary fat pad in a simple, less invasive, and easy-to-handle way, and this mouse orthotopic breast cancer model with a proper mammary fat pad environment can be used to investigate various aspects of cancer.

A proper animal model is crucial for a better understanding of diseases. Animal models established by different methods (subcutaneous injections, ...

Rat Mammary Epithelial Cell Transplantation into the Interscapular White Fat Pad

As early as the 1970s, researchers have successfully transplanted mammary epithelial cells into the interscapular white fat pad of rats. Grafting mammary epithelium using transplantation techniques takes advantage of the hormonal environment provided by the adolescent rodent host. These studies are ideally suited to explore the impact of various biological manipulations on mammary gland development and dissect many aspects of mammary gland biology. A common, but limiting, feature is that transplanted epithelial cells are strongly influenced by the surrounding stroma and outcompeted by endogenous epithelium; to utilize native mammary tissue, the abdominal-inguinal white fat pad must be cleared to remove host mammary epithelium prior to the transplantation. A major obstacle when using the rat model organism is that clearing the developing mammary tree in post-weaned rats is not efficient. When transplanted into gland-free fat pads, donor epithelial cells can repopulate the cleared host fat pad and form a functional mammary gland. The interscapular fat pad is an alternative location for these grafts. A major advantage is that it lacks ductal structures yet provides the normal stroma that is necessary to promote epithelial outgrowth and is easily accessible in the rat. Another major advantage of this technique is that it is minimally invasive, because it eliminates the need to cauterize and remove the growing endogenous mammary tree. Additionally, the interscapular fat pad contains a medial blood vessel that can be used to separate sites for grafting. Because the endogenous glands remain intact, this technique can also be used for studies comparing the endogenous mammary gland to the transplanted gland. This paper describes the method of mammary epithelial cell transplantation into the interscapular white fat pad of rats.

This article describes a transplantation method to graft donor rat mammary epithelial cells into the interscapular white fat pad of recipient animals. This method can be used to examine host and/or donor effects on mammary epithelium development and eliminates the need for pre-clearing, thereby extending the usefulness of this technique.

As early as the 1970s, researchers have successfully transplanted mammary epithelial cells into the interscapular white fat pad of rats. Grafting mammary ...

Modeling Brain Metastases Through Intracranial Injection and Magnetic Resonance Imaging

Metastatic spread of cancer is an unfortunate consequence of disease progression, aggressive cancer subtypes, and/or late diagnosis. Brain metastases are particularly devastating, difficult to treat, and confer a poor prognosis. While the precise incidence of brain metastases in the United States remains hard to estimate, it is likely to increase as extracranial therapies continue to become more efficacious in treating cancer. Thus, it is necessary to identify and develop novel therapeutic approaches to treat metastasis at this site. To this end, intracranial injection of cancer cells has become a well-established method in which to model brain metastasis. Previously, the inability to directly measure tumor growth has been a technical hindrance to this model; however, increasing availability and quality of small animal imaging modalities, such as magnetic resonance imaging (MRI), are vastly improving the ability to monitor tumor growth over time and infer changes within the brain during the experimental period. Herein, intracranial injection of murine mammary tumor cells into immunocompetent mice followed by MRI is demonstrated. The presented injection approach utilizes isoflurane anesthesia and a stereotactic setup with a digitally controlled, automated drill and needle injection to enhance precision, and reduce technical error. MRI is measured over time using a 9.4 Tesla instrument in The Ohio State University James Comprehensive Cancer Center Small Animal Imaging Shared Resource. Tumor volume measurements are demonstrated at each time point through use of ImageJ. Overall, this intracranial injection approach allows for precise injection, day-to-day monitoring, and accurate tumor volume measurements, which combined greatly enhance the utility of this model system to test novel hypotheses on the drivers of brain metastases.

Intracranial brain metastasis modeling is complicated by an inability to monitor tumor size and response to treatment with precise and timely methods. The presented methodology couples intracranial tumor injection with magnetic resonance imaging analysis, which when combined, cultivates precise and consistent injections, enhanced animal monitoring, and accurate tumor volume measurements.

Metastatic spread of cancer is an unfortunate consequence of disease progression, aggressive cancer subtypes, and/or late diagnosis. Brain metastases are ...

Modeling Breast Cancer in Human Breast Tissue using a Microphysiological System

Breast cancer (BC) remains a leading cause of death for women. Despite more than $700 million invested in BC research annually, 97% of candidate BC drugs fail clinical trials. Therefore, new models are needed to improve our understanding of the disease. The NIH Microphysiological Systems (MPS) program was developed to improve the clinical translation of basic science discoveries and promising new therapeutic strategies. Here we present a method for generating MPS for breast cancers (BC-MPS). This model adapts a previously described approach of culturing primary human white adipose tissue (WAT) by sandwiching WAT between adipose-derived stem cell sheets (ASC)s. Novel aspects of our BC-MPS include seeding BC cells into non-diseased human breast tissue (HBT) containing native extracellular matrix, mature adipocytes, resident fibroblasts, and immune cells; and sandwiching the BC-HBT admixture between HBT-derived ASC sheets. The resulting BC-MPS is stable in culture ex vivo for at least 14 days. This model system contains multiple elements of the microenvironment that influence BC including adipocytes, stromal cells, immune cells, and the extracellular matrix. Thus BC-MPS can be used to study the interactions between BC and its microenvironment. 
We demonstrate the advantages of our BC-MPS by studying two BC behaviors known to influence cancer progression and metastasis: 1) BC motility and 2) BC-HBT metabolic crosstalk. While BC motility has previously been demonstrated using intravital imaging, BC-MPS allows for high-resolution time-lapse imaging using fluorescence microscopy over several days. Furthermore, while metabolic crosstalk was previously demonstrated using BC cells and murine pre-adipocytes differentiated into immature adipocytes, our BC-MPS model is the first system to demonstrate this crosstalk between primary human mammary adipocytes and BC cells in vitro.

This protocol describes the construction of an in vitro microphysiological system for studying breast cancer using primary human breast tissue with off the shelf materials.

Breast cancer (BC) remains a leading cause of death for women. Despite more than $700 million invested in BC research annually, 97% of candidate BC drugs ...

Modeling Brain Metastasis Via Tail-Vein Injection of Inflammatory Breast Cancer Cells

Metastatic spread to the brain is a common and devastating manifestation of many types of cancer. In the United States alone, about 200,000 patients are diagnosed with brain metastases each year. Significant progress has been made in improving survival outcomes for patients with primary breast cancer and systemic malignancies; however, the dismal prognosis for patients with clinical brain metastases highlights the urgent need to develop novel therapeutic agents and strategies against this deadly disease. The lack of suitable experimental models has been one of the major hurdles impeding advancement of our understanding of brain metastasis biology and treatment. Herein, we describe a xenograft mouse model of brain metastasis generated via tail-vein injection of an endogenously HER2-amplified cell line derived from inflammatory breast cancer (IBC), a rare and aggressive form of breast cancer. Cells were labeled with firefly luciferase and green fluorescence protein to monitor brain metastasis, and quantified metastatic burden by bioluminescence imaging, fluorescent stereomicroscopy, and histologic evaluation. Mice robustly and consistently develop brain metastases, allowing investigation of key mediators in the metastatic process and the development of preclinical testing of new treatment strategies.

We describe a xenograft mouse model of breast cancer brain metastasis generated via tail-vein injection of an endogenously HER2-amplified inflammatory breast cancer cell line.

Metastatic spread to the brain is a common and devastating manifestation of many types of cancer. In the United States alone, about 200,000 patients are ...

Mammary Epithelial and Endothelial Cell Spheroids as a Potential Functional In vitro Model for Breast Cancer Research

Breast cancer is the leading cause of mortality in women. The growth of breast cancer cells and their subsequent metastasis is a key factor for its progression. Although the mechanisms involved in promoting breast cancer growth have been intensively studied using monocultures of breast cancer cells such as MCF-7 cells, the contribution of other cell types, such as vascular and lymphatic endothelial cells that are intimately involved in tumor growth, has not been investigated in depth. Cell-cell interaction plays a key role in tumor growth and progression. Neoangiogenesis, or the development of vessels, is essential for tumor growth, whereas the lymphatic system serves as a portal for cancer cell migration and subsequent metastasis. Recent studies provide evidence that vascular and lymphatic endothelial cells can significantly influence cancer cell growth. These observations imply a need for developing in vitro models that would more realistically reflect breast cancer growth processes in vivo. Moreover, restrictions in animal research require the development of ex vivo models to elucidate better the mechanisms involved.
This article describes the development of breast cancer spheroids composed of both breast cancer cells (estrogen receptor-positive MCF-7 cells) and vascular and/or lymphatic endothelial cells. The protocol describes a detailed step-by-step approach in creating dual-cell spheroids using two different approaches, hanging drop (gold standard and cheap) and 96-well U-bottom plates (expensive). In-depth instructions are provided for how to delicately pick up the formed spheroids to monitor growth by microscopic sizing and assessing viability using dead and live cell staining. Moreover, procedures to fix the spheroids for sectioning and staining with growth-specific antibodies to differentiate growth patterns in spheroids are delineated. Additionally, details for preparing spheroids with transfected cells and methods to extract RNA for molecular analysis are provided. In conclusion, this article provides in-depth instructions for preparing multi-cell spheroids for breast cancer research.

Mammary Epithelial and Endothelial Cell Spheroids as a Potential Functional In vitro Model for Breast Cancer Research

Crosstalk between mammary epithelial cells and endothelial cells importantly contributes to breast cancer progression, tumor growth, and metastasis. In this study, spheroids have been made from breast cancer cells together with vascular and/or lymphatic endothelial cells and demonstrate their applicability as an in vitro system for breast cancer research.

Breast cancer is the leading cause of mortality in women. The growth of breast cancer cells and their subsequent metastasis is a key factor for its ...