Supported by grants from the National Institute of Health grants CA133085, CA182518 and CA185909 (to KL) and VA Merit Review Award BX001962 (to KL).

All procedures follow guidelines and approved protocols by Georgia Regents University Animal Use and Care Committee.
1. Establishment of Orthotopic Breast Cancer Tumor
<ol>
	<li>One day before the experiment, culture approximately 2 x 106 4T1-Luc tumor cells in a 10-cm culture dish in 10 ml RPMI medium containing 10% FBS. Incubate the culture dish in a CO2 incubator at 37 &#176;C and 5% CO2.</li>
	<li>On the day of tumor cell injection, remove culture medium from the culture dish with vacuum, add 5 ml sterile phosphate buffered saline (PBS), pH 7.4 to the culture dish, and gently shake the dish to wash the culture surface, remove the PBS by vacuum.</li>
	<li>Add 2 ml trypsin-EDTA (0.05% Trypsin and 0.53 mM EDTA) to the culture dish, incubate it in the CO2 incubator at 37 &#176;C for about 5 min. Check cells on an inverted microscope to make sure that all cells are detached from the bottom of the culture dish.</li>
	<li>Quench the trypsin by adding 8 ml serum-containing medium, transfer cells to a 15-ml conical tube and centrifuge the cells at approximately 450 x g for 3 min at RT.</li>
	<li>Remove the supernatant by vacuum and resuspend cells in 10 ml PBS. Centrifuge cells at approximately 450 x g for 3 min. Remove the supernatant by vacuum, and resuspend cells in 10 ml PBS.</li>
	<li>Pipette 10 &#956;l of the cell suspension onto a hemocytometer under the cover glass. Count the cells to determine the cell concentration. Resuspend cells in PBS at a density of 2 x 105 cells/ml HBSS. Transfer cells to a 1.5 ml sterile microfuge tube and keep cells on ice until use.</li>
	<li>Use female BALB/c mice of 6 - 8 week for tumor cell injection.
	<ol>
		<li>Shave hair near surrounding nipple # 3 using an electronic hair trimmer. Injection of 4T1 cell into the mammary gland 3 fat pad reproducibly generates lung metastasis. Clean the shaved area by using the cotton swab dipped into 70% ethanol. Resuspend cells by inverting the microcentrifuge tube 2 - 3 times. Gently aspirate 50 &#181;l of cell suspension into a &#189; CC 27 G 1/2 tuberculin syringe.</li>
		<li>Inject the tumor cells into the mammary fat pad under #3 mammary gland of a BALB/c mouse. Place the mouse in a clean cage and return the cage to animal housing facility. Wait approximately 21 - 30 days for tumor development.&#160;Tumor growth should be monitored on a regular basis as per institution&#8217;s policies for tumor studies.</li>
	</ol>
	</li>
</ol>
2. Live Mouse Bioluminescence Imaging of Tumor Growth
<ol>
	<li>Image mice every 3 days after tumor injection Transfer mice to the imaging facility. Inject 100 &#956;l luciferin (30 mg/ml in PBS) intraperitoneally (i.p.) to mice prior to imaging. After approximately 10 min, anesthetize mice in an induction chamber with 2% isoflurane/O2 flow. Use the forceps to touch the leg of the mouse. No response to the touch confirms that the mouse is fully unconscious.
	<ol>
		<li>Place the mice in the imaging chamber with continuous 2% isoflurane and O2&#160;at a flow rate of 2 L/min.&#160;&#160;Place the mouse such that the area of interest (i.e., the mammary pad of the initial tumor injection) faces the camera of the imaging system. Ensure the nose and mouth of the mouse are firmly set within the anesthetic tubing.&#160;Animals should be anesthetized per veterinary standards at the institution.</li>
	</ol>
	</li>
	<li>Acquire bioluminescence imaging with an array of various exposure time. For instance, set exposure to 30, field of view (FOV) to 25, object height to 1.5 cm, and obtain luminescent photographic images with low power X-ray. Set the units of measurement to &#34;radiance.&#34;
	<ol>
		<li>Use an automatic linear color range with a maximum of approximately 2.4 x 107 radiance units. After acquiring initial images, adjust settings and obtain an optimized-image (Figures 3 &#38; 4).</li>
	</ol>
	</li>
	<li>Return mice to clean cages and ensure mice regain consciousness with ambulation before returning the animals to the housing facility.</li>
	<li>Analyze data with the living imaging software associated with the imaging instrument. Using an imaging program, draw an enclosed line around the region of interest (ROI). Use the imaging software to determine the radiance intensity of the ROI. Record the relative intensities of each ROI for each mouse. 
	NOTE: Higher radiance intensities indicate greater levels of luminescent cells, and thus greater tumor growth.</li>
	<li>Visually examine the mouse every 3 days for adverse effects. 
	NOTE: Mice will be weighed once a week. A weight loss of 15% body weight will be considered adverse effect and the tumor-bearing mice will be euthanized as described in step 5. Mice with ulcerated tumors will also be euthanized.</li>
</ol>
3. Surgical Removal of Primary Tumors
NOTE: Autoclave scissors, forceps and the wound clips and wound clip applier (Figure 1).
<ol>
	<li>Perform the surgery in a sterile hood to maintain a sterile condition to reduce risk of infection. One day before surgery, shave the area surrounding the tumors of the tumor-bearing mice with an electric hair trimmer.</li>
	<li>Approximately 2 - 4 hr before surgery, feed the mice chewable carprofen tablets formulated for mice at a dose of 5 mg/kg body weight.</li>
	<li>Put the mice in a chamber containing 2% isoflurane in oxygen for approximately 30 sec. Continuously anesthetize the mouse using an anesthesia apparatus during the entire surgical period.</li>
	<li>Use a sterile cotton stick to apply vet ointment to the eyes of the mouse to prevent dryness while under anesthesia. Use the forceps to touch the leg of the mouse. No response to the touch confirms that the mouse is fully unconscious.</li>
	<li>Disinfect the skin area around the tumor site with three alternating wipes of a soap disinfectant scrub. Wipe the surgical area with a 70% alcohol wipe.</li>
	<li>Use a sterilized scalpel (Figure 1) to cut a small incision near the tumor.</li>
	<li>Insert the tip of a pair of sterilized scissors to the incision to cut the skin around the tumor to expose the tumor nodule (Figure 2A). Hold the tumor with sterile forceps and use the scissors to separate the tumor from the skin (Figure 2B). Save the tumor sample by freezing in a -80 &#176;C freezer or by fixing in 10% formalin solution for future use.</li>
	<li>Close the surgical site with 9 mm wound clips using the auto-clip applier (Figure 1). Return the mouse to a clean cage with autoclaved bedding.&#160;The animals should be monitored per institutional guidelines. 
	NOTE: The mouse usually regains sufficient consciousness and starts to move in the cage approximately 10 - 30 min after the surgery.</li>
	<li>Administer carprofen to mice again 24 hr after surgery. Carprofen is for post-surgery analgesia and prescribing of post-surgery analgesia should be verified by direct consultation with the institution&#8217;s veterinary staff.&#160;&#160;Remove wound clips after the wound heals (usually within 5 - 7 days after surgery). Remove wound clips using the auto-clip remover.</li>
</ol>
4. Live Mouse Bioluminescence Imaging of Tumor Metastasis
<ol>
	<li>Image mice every 3 days after surgery as described in step 2.</li>
</ol>
5. Validation of Lung Metastases Using India Ink Inflation of Tumor-bearing Lungs
NOTE: To validate the luciferase live tumor imaging results, perform India ink inflation of tumor-bearing mouse lungs to quantify tumor nodules. 4T1 cells also metastasize to other organs and tissues (Figure 5) and therefore, histological examination of these organs to validate tumor metastasis should be performed if needed. This protocol use lung metastasis as a example.
<ol>
	<li>Keep mice in their existing home cage for euthanasia. When housed with other animals, relocate those mice not being euthanized to a different cage.</li>
	<li>Remove the cage filter top and replace with the CO2 filter top. Turn on the compressed CO2 gas cylinder (100%) that is connected to the CO2 filter top. Set the flow rate at 2 L/min and keep CO2 on for at least 10 min. If the mice are still breathing at the end of 10 min, leave the CO2 on until at least 1 min after mice stop breathing. Turn off CO2 cylinder control and the flow meter. Wait for 3 more minutes and remove the filter top.</li>
	<li>Place the sacrificed-mouse on its back on a polystyrene board. Pin the legs to ensure unobstructed access to the trachea. Spray the mice with 70% ethanol.</li>
	<li>Using a pair of scissors, cut along the midline of the mid-abdomen of the mouse through the ribcage and up toward the salivary glands. Observe the trachea. Use forceps to remove tissues surrounding the trachea to expose the trachea.</li>
	<li>Thread a pipette tip underneath the trachea. Holding the tip with one hand, gently lift the trachea up and away from the body.</li>
	<li>Rotate the platform holding the mouse 180&#176;. Use a &#189; CC 27 G 1/2 tuberculin syringe to inject India Ink (10% India ink and 0.1% Ammonium Hydroxide) into the lungs via the trachea. Completely inflate the lungs with ink until a strong resistance is felt.</li>
	<li>Use a pair of scissors to cut the trachea. Use forceps to hold the mouse and insert another set of forceps under the lungs and pull the lung lobes out of the mouse. Rinse the lungs briefly in a beaker containing water.</li>
	<li>In a chemical fume hood, transfer the lungs to a glass scintillation vial containing 3 ml of Fekete&#39;s solution (50% Ethanol, 6% Formaldehyde, and 3% glacial acetic acid). Cap the vial to prevent the solution from evaporating. 
	NOTE: The tissues can be stored in Fekete&#39;s solution indefinitely.</li>
	<li>After a few minutes, observe tumor nodules as white dots on the black lungs (Figure 5). The white tumor nodule is visible by eyes. Transfer the lungs to a dish in a fume hood and count the number of white spots. Each white spot represents a single metastatic tumor nodule.</li>
</ol>

<ol>
	<li>Fantozzi, A., Christofori, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+of+breast+cancer+metastasis.">Mouse models of breast cancer metastasis.</a> Breast Cancer Res. 8, 212 (2006).</li><li>Weigelt, B., Peterse, J. L., van 't Veer, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breast+cancer+metastasis:+markers+and+models.">Breast cancer metastasis: markers and models.</a> Nat Rev Cancer. 5, 591-602 (2005).</li><li>Kocaturk, B., Versteeg, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Orthotopic+injection+of+breast+cancer+cells+into+the+mammary+fat+pad+of+mice+to+study+tumor+growth.">Orthotopic injection of breast cancer cells into the mammary fat pad of mice to study tumor growth.</a> J Vis Exp. , (2015).</li><li>Stewart, T. J., Abrams, S. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+tumours+escape+mass+destruction.">How tumours escape mass destruction.</a> Oncogene. 27, 5894-5903 (2008).</li><li>Lopez, J. I., 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=CD44+attenuates+metastatic+invasion+during+breast+cancer+progression.">CD44 attenuates metastatic invasion during breast cancer progression.</a> Cancer Res. 65, 6755-6763 (2005).</li><li>Khanna, C., Hunter, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+metastasis+in+vivo.">Modeling metastasis in vivo.</a> Carcinogenesis. 26, 513-523 (2005).</li><li>Cuevas, B. D., Winter-Vann, A. M., Johnson, N. L., Johnson, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MEKK1+controls+matrix+degradation+and+tumor+cell+dissemination+during+metastasis+of+polyoma+middle-T+driven+mammary+cancer.">MEKK1 controls matrix degradation and tumor cell dissemination during metastasis of polyoma middle-T driven mammary cancer.</a> Oncogene. 25, 4998-5010 (2006).</li><li>Danna, E. 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=Surgical+removal+of+primary+tumor+reverses+tumor-induced+immunosuppression+despite+the+presence+of+metastatic+disease.">Surgical removal of primary tumor reverses tumor-induced immunosuppression despite the presence of metastatic disease.</a> Cancer Res. 64, 2205-2211 (2004).</li><li>Tao, K., Fang, M., Alroy, J., Sahagian, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imagable+4T1+model+for+the+study+of+late+stage+breast+cancer.">Imagable 4T1 model for the study of late stage breast cancer.</a> BMC Cancer. 8, 228 (2008).</li><li>Hu, 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=Deregulation+of+apoptotic+factors+Bcl-xL+and+Bax+confers+apoptotic+resistance+to+myeloid-derived+suppressor+cells+and+contributes+to+their+persistence+in+cancer.">Deregulation of apoptotic factors Bcl-xL and Bax confers apoptotic resistance to myeloid-derived suppressor cells and contributes to their persistence in cancer.</a> J Biol Chem. 288, 19103-19115 (2013).</li><li>Kwan, H., 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=Transgenes+expressing+the+Wnt-1+and+int-2+proto-oncogenes+cooperate+during+mammary+carcinogenesis+in+doubly+transgenic+mice.">Transgenes expressing the Wnt-1 and int-2 proto-oncogenes cooperate during mammary carcinogenesis in doubly transgenic mice.</a> Mol Cell Biol. 12, 147-154 (1992).</li><li>Guy, C. T., Cardiff, R. D., Muller, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+mammary+tumors+by+expression+of+polyomavirus+middle+T+oncogene:+a+transgenic+mouse+model+for+metastatic+disease.">Induction of mammary tumors by expression of polyomavirus middle T oncogene: a transgenic mouse model for metastatic disease.</a> Mol Cell Biol. 12, 954-961 (1992).</li><li>Almholt, 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=Reduced+metastasis+of+transgenic+mammary+cancer+in+urokinase-deficient+mice.">Reduced metastasis of transgenic mammary cancer in urokinase-deficient mice.</a> Int J Cancer. 113, 525-532 (2005).</li><li>Gallego, M. I., Bierie, B., Hennighausen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeted+expression+of+HGF/SF+in+mouse+mammary+epithelium+leads+to+metastatic+adenosquamous+carcinomas+through+the+activation+of+multiple+signal+transduction+pathways.">Targeted expression of HGF/SF in mouse mammary epithelium leads to metastatic adenosquamous carcinomas through the activation of multiple signal transduction pathways.</a> Oncogene. 22, 8498-8508 (2003).</li><li>Lin, S. 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=Somatic+mutation+of+p53+leads+to+estrogen+receptor+alpha-positive+and+-negative+mouse+mammary+tumors+with+high+frequency+of+metastasis.">Somatic mutation of p53 leads to estrogen receptor alpha-positive and -negative mouse mammary tumors with high frequency of metastasis.</a> Cancer Res. 64, 3525-3532 (2004).</li><li>Ridgeway, A. G., McMenamin, J., Leder, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=P53+levels+determine+outcome+during+beta-catenin+tumor+initiation+and+metastasis+in+the+mammary+gland+and+male+germ+cells.">P53 levels determine outcome during beta-catenin tumor initiation and metastasis in the mammary gland and male germ cells.</a> Oncogene. 25, 3518-3527 (2006).</li><li>Zimmerman, M., Hu, X., Liu, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+metastasis+and+CTL+adoptive+transfer+immunotherapy+mouse+model.">Experimental metastasis and CTL adoptive transfer immunotherapy mouse model.</a> J Vis Exp. , (2010).</li></ol>

Mice were purchased from the Jackson Laboratory and housed in the Georgia Regents University animal facility. Experiments and care/welfare were in agreement with federal regulations and an approved protocol by the Georgia Regents University IACUC committee. The authors have nothing to disclose.

Many types of transgenic mouse models of breast cancer metastasis have been developed.1 These transgenic mice have high tumor incidence ranging from 60 to 100%. However, the metastasis incidence of these transgenic mice is much lower than the tumor incidence (14 - 100%). Tumor cells metastasize to LN and lungs in the majority of these transgenic mouse models of breast cancer metastasis. The metastasis latency varies from model to model and ranges from 2 to 8 months.6,11-16 These transgenic mouse mod...

According to the American Cancer Society, breast cancer is the most frequently diagnosed form of cancer in women in the United States. Early detection in combination with recently developed targeted therapies has significantly reduced the mortality of breast cancer in the last two decades. However, breast cancer is still the second leading cause of cancer-related death in women in the United States1. The majority of deaths of breast cancer patients are due to tumor cell metastasis. Unfortunately, most breast cancer is invasive and frequently metastasizes to the lymph node and subsequently to distant organs, including bone, lung, liver and brain.1,2 There is currently no effective therapy for metastatic breast cancer. Therefore, development of chemotherapeutic and immunotherapeutic agents to suppress metastatic breast cancer is of great significance.
Various breast cancer spontaneous metastasis mouse models have been developed to study the molecular mechanisms underlying breast tumor cell progression and metastasis and to be used as models for the development of therapeutic agents.1,3-5 However, most of these mouse models are genetic tumor models that, while excellent models for mechanistic studies, are not suitable for testing therapeutic agents since the metastasis takes months to develop in these genetic models, thereby requiring costly long-term administration of the anti-cancer agents.6,7 Monitoring tumor progression in live mice is also technically challenging. In contrast, a transplanted breast cancer metastasis model has the advantages of short term tumor progression and easy tracking of tumor progression in live mice. The 4T1 orthotopic breast cancer spontaneous metastasis mouse model is such a transplanted tumor model.8 In this model, the breast tumor cells are transplanted into the mammary fat pad to establish primary tumor nodules. The primary tumor can then be surgically removed as in human breast cancer patients. 4T1 tumor cells are highly invasive.8,9,3,10 Almost all tumor-bearing mice develop metastasis in 30 days after tumor transplant into the mammary fat pad. However, 4T1 tumors grow aggressively in the primary sites and the tumor sizes often exceed the limits that are allowed in most animal protocols. At this stage, the metastases are often micrometastases. Therefore, it is essential to remove primary tumors to allow metastasis progress for testing therapeutic agents. Here, we report the establishment of a simple and yet sensitive procedure of primary tumor transplant, surgical removal of primary tumor and bioluminescence imaging-based quantification of the 4T1 tumor growth and progression in vivo.

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			<td height="21" style="height:21px;width:251px;">Ami-X Imaging System&#160;</td>
			<td style="width:437px;">Spectral Instruments Imaging Inc. Tucson, AZ</td>
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			<td style="width:437px;">Anesthesia Service &#38; Equipment , Inc., Atlanta, GA</td>
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			<td height="21" style="height:21px;width:251px;">AutoClip Physicians Kit</td>
			<td style="width:437px;">Becton Dickinson Primary Care Diagnostics. Sparks, MD</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:251px;">9 MM AutoClip Applier&#160;</td>
			<td style="width:437px;">Becton Dickinson Primary Care Diagnostics. Sparks, MD</td>
			<td style="width:119px;">427630</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:251px;">9 MM AutoClip Remover</td>
			<td style="width:437px;">Becton Dickinson Primary Care Diagnostics. Sparks, MD</td>
			<td style="width:119px;">427637</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:251px;">9 MM AutoClip Wound Clip</td>
			<td style="width:437px;">Becton Dickinson Primary Care Diagnostics. Sparks, MD</td>
			<td style="width:119px;">427631</td>
			<td></td>
		</tr>
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			<td height="21" style="height:21px;width:251px;">Sharp-Pointed Dissecting Scissors</td>
			<td style="width:437px;">Fisher</td>
			<td style="width:119px;">8940</td>
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			<td height="21" style="height:21px;">Dissecting Fine-Pointed Forceps</td>
			<td style="width:437px;">Fisher</td>
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			<td height="21" style="height:21px;">1/2 CC 27G1/2 tuberculin syringe&#160;</td>
			<td style="width:437px;">Becton Dickinson and Co. NJ&#160;</td>
			<td style="width:119px;">305620</td>
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			<td height="21" style="height:21px;width:251px;">PBS</td>
			<td style="width:437px;">Mediatech Inc</td>
			<td style="width:119px;">21-040-CV</td>
			<td></td>
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			<td height="21" style="height:21px;width:251px;">70% Ethanol</td>
			<td style="width:437px;">Ultrapure-usa.com</td>
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			<td height="21" style="height:21px;width:251px;">Trypsin-EDTA</td>
			<td style="width:437px;">Mediatech Inc</td>
			<td style="width:119px;">25-040-CI</td>
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an orthotopic mouse model of spontaneous breast cancer metastasis

Metastasis is the primary cause of mortality of breast cancer patients. The mechanism underlying cancer cell metastasis, including breast cancer metastasis, is largely unknown and is a focus in cancer research. Various breast cancer spontaneous metastasis mouse models have been established. Here, we report a simplified procedure to establish orthotopic transplanted breast cancer primary tumor and resultant spontaneous metastasis that mimic human breast cancer metastasis. Combined with the bioluminescence live tumor imaging, this mouse model allows tumor growth and progression kinetics to be monitored and quantified. In this model, a low dose (1 x 104 cells) of 4T1-Luc breast cancer cells was injected into BALB/c mouse mammary fat pad using a tuberculin syringe. Mice were injected with luciferin and imaged at various time points using a bioluminescent imaging system. When the primary tumors grew to the size limit as in the IACUC-approved protocol (approximately 30 days), mice were anesthetized under constant flow of 2% isoflurane and oxygen. The tumor area was sterilized with 70% ethanol. The mouse skin around the tumor was excised to expose the tumor which was removed with a pair of sterile scissors. Removal of the primary tumor extends the survival of the 4T-1 tumor-bearing mice for one month. The mice were then repeatedly imaged for metastatic tumor spreading to distant organs. Therapeutic agents can be administered to suppress tumor metastasis at this point. This model is simple and yet sensitive in quantifying breast cancer cell growth in the primary site and progression kinetics to distant organs, and thus is an excellent model for studying breast cancer growth and progression, and for testing anti-metastasis therapeutic and immunotherapeutic agents in vivo.

Establishment of Orthotopic Breast Cancer Mouse Model 
4T1 is an aggressive mammary carcinoma cell line. Injection of as little as 1 x 104 cells into the mammary fat pad can lead to establishment of a single tumor nodule in the site of injection (Figure 2A). Therefore, the tumor mimics human primary mammary carcinoma. Almost 100% mice develop the orthotopic tumor. The tumor size can be quantified using a digital caliper or by live tumor im...

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An Orthotopic Mouse Model of Spontaneous Breast Cancer Metastasis

An orthotopic breast cancer primary tumor model and surgical removal of primary tumor to extend mouse life to generate spontaneous metastasis are described. The tumor growth and progression are monitored and quantified by luciferase fluorescence imaging.

Metastasis is the primary cause of mortality of breast cancer patients. The mechanism underlying cancer cell metastasis, including breast cancer ...

The overall goal of this procedure is to establish a mouse spontaneous metastasis breast cancer model that allows the quantification of primary tumor breast cancer growth as well as the visualization and measurement of the breast cancer metastasis kinetics.This method can help answer key questions in the field of spontaneous cancer metastasis, such as how can altering tumor-associated genes affect cancer growth and metastasis?The main advantage of this technique is that this model mimics human breast cancer development, making it ideal for testing the efficacy of therapeutic agents.On the day of the experiment, harvest an overnight culture of 4T1 luciferase tumor cells, and pellet the cells by centrifugation.Remove the supernatant by vacuum, then wash the cells in 10ml of PBS, and re-suspend the pellet in 10ml of fresh PBS for counting.Next, dilute the cells to 2x10^5 cells/ml concentration in HBSS, and output the suspension into 1.5ml sterile microcentrifuge tubes on ice.Then, restraining the mouse by hand, label the mammary glands of a 6-8 week-old female BALB/c mouse with a black marker, and use an electronic hair trimmer to shave the hairs surrounding the number 3 nipple.Proceed to re-suspend the cells by 2-3 inversions of the microfuge tube, then carefully aspirate 50

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30.5K Views.  Augusta University. The overall goal of this procedure is to establish a mouse spontaneous metastasis breast cancer model that allows the quantification of primary tumor breast cancer growth as well as the visualization and measurement of the breast cancer metastasis kinetics.This method can help answer key questions in the field of spontaneous cancer metastasis, such as how can altering tumor-associated genes affect cancer growth and metastasis?The main advantage of this technique is that this model mimics huma...

Video: An Orthotopic Mouse Model of Spontaneous Breast Cancer Metastasis

An Orthotopic Model of Murine Bladder Cancer

In this straightforward procedure, bladder tumors are established in female C57 mice through the use of catheterization, local cauterization, and subsequent cell adhesion. After their bladders are transurethrally catheterized and drained, animals are again catheterized to permit insertion of a platinum wire into bladders without damaging the urethra or bladder. The catheters are made of Teflon to serve as an insulator for the wire, which will conduct electrical current into the bladder to create a burn injury. An electrocautery unit is used to deliver 2.5W to the exposed end of the wire, burning away extracellular layers and providing attachment sites for carcinoma cells that are delivered in suspension to the bladder through a subsequent catheterization. Cells remain in the bladder for 90 minutes, after which the catheters are removed and the bladders allowed to drain naturally. The development of tumor is monitored via ultrasound. Specific attention is paid to the catheterization technique in the accompanying video.

Bladder tumors are established in female mice in a minimally invasive fashion through catheterization, local cauterization, and subsequent adhesion of carcinoma cells to the burn sites.

In this straightforward procedure, bladder tumors are established in female C57 mice through the use of catheterization, local cauterization, and ...

Quantitative Analysis of Cancer Metastasis using an Avian Embryo Model

During metastasis cancer cells disseminate from the primary tumor, invade into surrounding tissues, and spread to distant organs. Metastasis is a complex process that can involve many tissue types, span variable time periods, and often occur deep within organs, making it difficult to investigate and quantify. In addition, the efficacy of the metastatic process is influenced by multiple steps in the metastatic cascade making it difficult to evaluate the contribution of a single aspect of tumor cell behavior. As a consequence, metastasis assays are frequently performed in experimental animals to provide a necessarily realistic context in which to study metastasis. Unfortunately, these models are further complicated by their complex physiology. The chick embryo is a unique in vivo model that overcomes many limitations to studying metastasis, due to the accessibility of the chorioallantoic membrane (CAM), a well-vascularized extra-embryonic tissue located underneath the eggshell that is receptive to the xenografting of tumor cells (figure 1). Moreover, since the chick embryo is naturally immunodeficient, the CAM readily supports the engraftment of both normal and tumor tissues. Most importantly, the avian CAM successfully supports most cancer cell characteristics including growth, invasion, angiogenesis, and remodeling of the microenvironment. This makes the model exceptionally useful for the investigation of the pathways that lead to cancer metastasis and to predict the response of metastatic cancer to new potential therapeutics. The detection of disseminated cells by species-specific Alu PCR makes it possible to quantitatively assess metastasis in organs that are colonized by as few as 25 cells. Using the Human Epidermoid Carcinoma cell line (HEp3) we use this model to analyze spontaneous metastasis of cancer cells to distant organs, including the chick liver and lung. Furthermore, using the Alu-PCR protocol we demonstrate the sensitivity and reproducibility of the assay as a tool to analyze and quantitate intravasation, arrest, extravasation, and colonization as individual elements of metastasis.

Using quantitative PCR, we demonstrate how the well-established chick CAM model can be used to quantitatively analyze the metastasis of human tumor cells to distant organs.

During metastasis cancer cells disseminate from the primary tumor, invade into surrounding tissues, and spread to distant organs. Metastasis is a complex ...

Multi-photon Imaging of Tumor Cell Invasion in an Orthotopic Mouse Model of Oral Squamous Cell Carcinoma

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient management strategies. Orthotopic mouse models of oral cancer have been developed to facilitate the study of factors that impact invasion and serve as model system for evaluating anti-tumor therapeutics. In these systems, visualization of disseminated tumor cells within oral cavity tissues has typically been conducted by either conventional histology or with in vivo bioluminescent methods. A primary drawback of these techniques is the inherent inability to accurately visualize and quantify early tumor cell invasion arising from the primary site in three dimensions. Here we describe a protocol that combines an established model for squamous cell carcinoma of the tongue (SCOT) with two-photon imaging to allow multi-vectorial visualization of lingual tumor spread. The OSC-19 head and neck tumor cell line was stably engineered to express the F-actin binding peptide LifeAct fused to the mCherry fluorescent protein (LifeAct-mCherry). Fox1nu/nu mice injected with these cells reliably form tumors that allow the tongue to be visualized by ex-vivo application of two-photon microscopy. This technique allows for the orthotopic visualization of the tumor mass and locally invading cells in excised tongues without disruption of the regional tumor microenvironment. In addition, this system allows for the quantification of tumor cell invasion by calculating distances that invaded cells move from the primary tumor site. Overall this procedure provides an enhanced model system for analyzing factors that contribute to SCOT invasion and therapeutic treatments tailored to prevent local invasion and distant metastatic spread. This method also has the potential to be ultimately combined with other imaging modalities in an in vivo setting.

A comprehensive overview of the techniques involved in generating a mouse model of oral cancer and quantitative monitoring of tumor invasion within the tongue through multi-photon microscopy of labeled cells is presented. This system can serve as a useful platform for the molecular assessment and drug efficacy of anti-invasive compounds.

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient ...

In vivo Bioluminescence Imaging of Tumor Hypoxia Dynamics of Breast Cancer Brain Metastasis in a Mouse Model

It is well recognized that tumor hypoxia plays an important role in promoting malignant progression and affecting therapeutic response negatively. There is little knowledge about in situ, in vivo, tumor hypoxia during intracranial development of malignant brain tumors because of lack of efficient means to monitor it in these deep-seated orthotopic tumors. Bioluminescence imaging (BLI), based on the detection of light emitted by living cells expressing a luciferase gene, has been rapidly adopted for cancer research, in particular, to evaluate tumor growth or tumor size changes in response to treatment in preclinical animal studies. Moreover, by expressing a reporter gene under the control of a promoter sequence, the specific gene expression can be monitored non-invasively by BLI. Under hypoxic stress, signaling responses are mediated mainly via the hypoxia inducible factor-1&alpha; (HIF-1&alpha;) to drive transcription of various genes. Therefore, we have used a HIF-1&alpha; reporter construct, 5HRE-ODD-luc, stably transfected into human breast cancer MDA-MB231 cells (MDA-MB231/5HRE-ODD-luc). In vitro HIF-1&alpha; bioluminescence assay is performed by incubating the transfected cells in a hypoxic chamber (0.1% O2) for 24 hr before BLI, while the cells in normoxia (21% O2) serve as a control. Significantly higher photon flux observed for the cells under hypoxia suggests an increased HIF-1&alpha; binding to its promoter (HRE elements), as compared to those in normoxia. Cells are injected directly into the mouse brain to establish a breast cancer brain metastasis model. In vivo bioluminescence imaging of tumor hypoxia dynamics is initiated 2 wks after implantation and repeated once a week. BLI reveals increasing light signals from the brain as the tumor progresses, indicating increased intracranial tumor hypoxia. Histological and immunohistochemical studies are used to confirm the in vivo imaging results. Here, we will introduce approaches of in vitro HIF-1&alpha; bioluminescence assay, surgical establishment of a breast cancer brain metastasis in a nude mouse and application of in vivo bioluminescence imaging to monitor intracranial tumor hypoxia.

In vivo Bioluminescence Imaging of Tumor Hypoxia Dynamics of Breast Cancer Brain Metastasis in a Mouse Model

Bioluminescence imaging of hypoxia inducible factor-1&alpha; activity is applied to monitor intracranial tumor hypoxia development in a breast cancer brain metastasis mouse model.

It is well recognized that tumor hypoxia plays an important role in promoting malignant progression and affecting therapeutic response negatively. There ...

Combination Radiotherapy in an Orthotopic Mouse Brain Tumor Model

Glioblastoma multiforme (GBM) are the most common and aggressive adult primary brain tumors1. In recent years there has been substantial progress in the understanding of the mechanics of tumor invasion, and direct intracerebral inoculation of tumor provides the opportunity of observing the invasive process in a physiologically appropriate environment2. As far as human brain tumors are concerned, the orthotopic models currently available are established either by stereotaxic injection of cell suspensions or implantation of a solid piece of tumor through a complicated craniotomy procedure3. In our technique we harvest cells from tissue culture to create a cell suspension used to implant directly into the brain. The duration of the surgery is approximately 30 minutes, and as the mouse needs to be in a constant surgical plane, an injectable anesthetic is used. The mouse is placed in a stereotaxic jig made by Stoetling (figure 1). After the surgical area is cleaned and prepared, an incision is made; and the bregma is located to determine the location of the craniotomy. The location of the craniotomy is 2 mm to the right and 1 mm rostral to the bregma. The depth is 3 mm from the surface of the skull, and cells are injected at a rate of 2 &mu;l every 2 minutes. The skin is sutured with 5-0 PDS, and the mouse is allowed to wake up on a heating pad. From our experience, depending on the cell line, treatment can take place from 7-10 days after surgery. Drug delivery is dependent on the drug composition. For radiation treatment the mice are anesthetized, and put into a custom made jig. Lead covers the mouse's body and exposes only the brain of the mouse. The study of tumorigenesis and the evaluation of new therapies for GBM require accurate and reproducible brain tumor animal models. Thus we use this orthotopic brain model to study the interaction of the microenvironment of the brain and the tumor, to test the effectiveness of different therapeutic agents with and without radiation.

The purpose of this article is to describe the use of an orthotopic glioblastoma model for chemoradiation studies. This article will go though cell processing, implanting, and radiotherapy of the mouse using an intracranial model.

Glioblastoma multiforme (GBM) are the most common and aggressive adult primary brain tumors1. In recent years there has been substantial progress in the ...

Multi-modal Imaging of Angiogenesis in a Nude Rat Model of Breast Cancer Bone Metastasis Using Magnetic Resonance Imaging, Volumetric Computed Tomography and Ultrasound

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell proliferation in the bone marrow cavity as well as for interaction of tumor and bone cells resulting in local bone destruction. Our aim was to develop a model of experimental bone metastasis that allows in vivo assessment of angiogenesis in skeletal lesions using non-invasive imaging techniques.
For this purpose, we injected 105 MDA-MB-231 human breast cancer cells into the superficial epigastric artery, which precludes the growth of metastases in body areas other than the respective hind leg1. Following 25-30 days after tumor cell inoculation, site-specific bone metastases develop, restricted to the distal femur, proximal tibia and proximal fibula1. Morphological and functional aspects of angiogenesis can be investigated longitudinally in bone metastases using magnetic resonance imaging (MRI), volumetric computed tomography (VCT) and ultrasound (US).
MRI displays morphologic information on the soft tissue part of bone metastases that is initially confined to the bone marrow cavity and subsequently exceeds cortical bone while progressing. Using dynamic contrast-enhanced MRI (DCE-MRI) functional data including regional blood volume, perfusion and vessel permeability can be obtained and quantified2-4. Bone destruction is captured in high resolution using morphological VCT imaging. Complementary to MRI findings, osteolytic lesions can be located adjacent to sites of intramedullary tumor growth. After contrast agent application, VCT angiography reveals the macrovessel architecture in bone metastases in high resolution, and DCE-VCT enables insight in the microcirculation of these lesions5,6. US is applicable to assess morphological and functional features from skeletal lesions due to local osteolysis of cortical bone. Using B-mode and Doppler techniques, structure and perfusion of the soft tissue metastases can be evaluated, respectively. DCE-US allows for real-time imaging of vascularization in bone metastases after injection of microbubbles7.
In conclusion, in a model of site-specific breast cancer bone metastases multi-modal imaging techniques including MRI, VCT and US offer complementary information on morphology and functional parameters of angiogenesis in these skeletal lesions.

In the pathogenesis of bone metastasis, angiogenesis is a crucial process and therefore represents a target for imaging and therapy. Here, we present a rat model of site-specific breast cancer bone metastasis and describe strategies to non-invasively image angiogenesis in vivo using magnetic resonance imaging, volumetric computed tomography and ultrasound.

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell ...

An Orthotopic Mouse Model of Anaplastic Thyroid Carcinoma

Several types of animal models of human thyroid carcinomas have been established, including subcutaneous xenograft and orthotopic implantation of cancer cells into immunodeficient mice. Subcutaneous xenograft models have been valuable for preclinical screening and evaluation of new therapeutic treatments. There are a number of advantages to using a subcutaneous model; 1) rapid, 2) reproducible, and 3) tumor establishment, growth, and response to therapeutic agents may be monitored by visual inspection. However, substantial evidence has shed light on the short-comings of subcutaneous xenograft models1-3. For instance, medicinal treatments demonstrating curative properties in subcutaneous xenograft models often have no notable impact on the human disease. The microenvironment of the site of xenographic transplantation or injection lies at the heart of this dissimilarity.
Orthotopic tumor xenograft models provide a more biologically relevant context in which to study the disease. The advantages of implanting diseased cells or tissue into their anatomical origin equivalent within a host animal includes a suitable site for tumor-host interactions, development of disease-related metastases and the ability to examine site-specific influence on investigational therapeutic remedies. Therefore, orthotopic xenograft models harbor far more clinical value because they closely reproduce human disease. For these reasons, a number of groups have taken advantage of an orthotopic thyroid cancer model as a research tool4-7.
Here, we describe an approach that establishes an orthotopic model for the study of anaplastic thyroid carcinoma (ATC), which is highly invasive, resists treatment, and is virtually fatal in all diagnosed patients. Cultured ATC cells are prepared as a dissociated cellular suspension in a solution containing a basement membrane matrix. A small volume is slowly injected into the right thyroid gland. Overall appearance and health of the mice are monitored to ensure minimal post-operative complications and to gauge pathological penetrance of the cancer. Mice are sacrificed at 4 weeks, and tissue is collected for histological analysis. Animals may be taken at later time-points to examine more advance progression of the disease. Production of this orthotopic mouse model establishes a platform that accomplishes two objectives: 1) further our understanding of ATC pathology, and 2) screen current and future therapeutic agents for efficacy in combating ATC.

Generation of an orthotopic mouse model of anaplastic thyroid carcinoma is described here. This technique employs surgical placement of human anaplastic thyroid cancer cells into the thyroid of immunodeficient mice, thus creating a more clinically relevant setting to study disease progression as well as screen innovative therapeutic interventions.

Several types of animal models of human thyroid carcinomas have been established, including subcutaneous xenograft and orthotopic implantation of cancer ...

An Orthotopic Bladder Cancer Model for Gene Delivery Studies

Bladder cancer is the second most common cancer of the urogenital tract and novel therapeutic approaches that can reduce recurrence and progression are needed. The tumor microenvironment can significantly influence tumor development and therapy response. It is therefore often desirable to grow tumor cells in the organ from which they originated. This protocol describes an orthotopic model of bladder cancer, in which MB49 murine bladder carcinoma cells are instilled into the bladder via catheterization. Successful tumor cell implantation in this model requires disruption of the protective glycosaminoglycan layer, which can be accomplished by physical or chemical means. In our protocol the bladder is treated with trypsin prior to cell instillation. Catheterization of the bladder can also be used to deliver therapeutics once the tumors are established. This protocol describes the delivery of an adenoviral construct that expresses a luciferase reporter gene. While our protocol has been optimized for short-term studies and focuses on gene delivery, the methodology of mouse bladder catheterization has broad applications.

Implantation of cancer cells into the organ of origin can serve as a useful preclinical model to evaluate novel therapies. MB49 bladder carcinoma cells can be grown within the bladder following intravesical instillation. This protocol demonstrates catheterization of the mouse bladder for the purpose of tumor implantation and adenoviral delivery.

Bladder cancer is the second most common cancer of the urogenital tract and novel therapeutic approaches that can reduce recurrence and progression are ...

Bioluminescent Orthotopic Model of Pancreatic Cancer Progression

Pancreatic cancer has an extremely poor five-year survival rate of 4-6%. New therapeutic options are critically needed and depend on improved understanding of pancreatic cancer biology. To better understand the interaction of cancer cells with the pancreatic microenvironment, we demonstrate an orthotopic model of pancreatic cancer that permits non-invasive monitoring of cancer progression. Luciferase-tagged pancreatic cancer cells are resuspended in Matrigel and delivered into the pancreatic tail during laparotomy. Matrigel solidifies at body temperature to prevent leakage of cancer cells during injection. Primary tumor growth and metastasis to distant organs are monitored following injection of the luciferase substrate luciferin, using in vivo imaging of bioluminescence emission from the cancer cells. In vivo imaging also may be used to track primary tumor recurrence after resection. This orthotopic model is suited to both syngeneic and xenograft models and may be used in pre-clinical trials to investigate the impact of novel anti-cancer therapeutics on the growth of the primary pancreatic tumor and metastasis.

Improved understanding of pancreatic cancer biology is critically needed to enable the development of better therapeutic options to treat pancreatic cancer. To address this need, we demonstrate an orthotopic model of pancreatic cancer that permits non-invasive monitoring of cancer progression using in vivo bioluminescence imaging.

Pancreatic cancer has an extremely poor five-year survival rate of 4-6%.  New therapeutic options are critically needed and depend on improved ...

An Orthotopic Murine Model of Human Prostate Cancer Metastasis

Our laboratory has developed a novel orthotopic implantation model of human prostate cancer (PCa). As PCa death is not due to the primary tumor, but rather the formation of distinct metastasis, the ability to effectively model this progression pre-clinically is of high value. In this model, cells are directly implanted into the ventral lobe of the prostate in Balb/c athymic mice, and allowed to progress for 4-6 weeks. At experiment termination, several distinct endpoints can be measured, such as size and molecular characterization of the primary tumor, the presence and quantification of circulating tumor cells in the blood and bone marrow, and formation of metastasis to the lung. In addition to a variety of endpoints, this model provides a picture of a cells ability to invade and escape the primary organ, enter and survive in the circulatory system, and implant and grow in a secondary site. This model has been used effectively to measure metastatic response to both changes in protein expression as well as to response to small molecule therapeutics, in a short turnaround time.

This orthotopic model of human prostate cancer allows for quantification of tumor size, circulating tumor cells, and formation of distinct metastasis to the lung. As cells must escape the primary organ, enter the blood stream, and implant into a secondary site, this model effectively recapitulates the scenario in humans.

Our laboratory has developed a novel orthotopic implantation model of  human prostate cancer (PCa). As PCa death is not due to the primary tumor, but  ...