We would like to thank NIH, LACaTS and Ochsner clinic foundation for the financial support.

All mouse experiments were done in accordance with protocols approved by the Institutional Animal Care and Use Committees (IACUC) of LSU School of Medicine. All instruments must be autoclaved prior to dissection.
1. Preparation of Primary Cells from Mouse Breast Tumors
<ol>
	<li>Use a mouse model that was genetically engineered with the Mouse Mammary Tumor Virus Polyoma Middle T-Antigen (MMTV-PyMT-transgenic mouse), which spontaneously develop tumors as previously described 6.</li>
	<li>Sacrifice mice with Isoflurane (99.9%) and spray 75% ethanol to ensure a sterile environment (Figure 1A).</li>
	<li>Open the skin from the area of the urethral orifice to the neck with scissors. Pin the skin down to allow easy access to organs (Figure 1B).</li>
	<li>Isolate the mammary breast tumor and wash with cold sterile phosphate buffered saline (PBS) (pH 7.4) (Figure 1C).</li>
	<li>Transfer the tumor to a sterile 10cm tissue culture plate and chop it with a sterile razor blade and scissors to approximately 1 mm3 pieces. Subsequent steps should be performed in a sterile laminar flow hood.</li>
	<li>Incubate the chopped tumor tissue with Collagenase dissolved in serum free DMEM media at a final concentration of 1mg/ml on a rocker for 2 hr at 37 &#176;C. Centrifuge the tumor tissue suspension for 3 min&#160;at 200 x g. 
	NOTE: The Collagenase incubation is essential for enzymatic dissociation of the tissue.</li>
	<li>Discard the supernatant and wash the precipitate 3 times with PBS (pH 7.4) by centrifuging for 3 min&#160;at 200 x g. After the final wash, decant the supernatant.</li>
	<li>Resuspend the tissue with 2 ml&#160;of trypsin EDTA for 5 min&#160;at 37 &#176;C while nutating. Centrifuge the suspension for 3 min&#160;at 200 x g and repeat the washes.</li>
	<li>Resuspend the tissue pellet in normal growth medium (DMEM, 10% FBS, 2X pen/strep) onto a 10cm plate. Change the media every day for the next 3 days. Culture cells until desired cell number is obtained. 
	NOTE: Approximately 1x107 cells will be isolated from this procedure. Other mouse mammary tumorigenesis models, such as MMTV-Neu, give lower yield of cells when compared to MMTV-PyMT. When using models that produce a lower yield, it is beneficial to begin with a larger tumor and culture cells longer.</li>
</ol>
2. Mouse Lung Extraction to Visualize Lung Metastasis
<ol>
	<li>Prior to lung extraction, remove the liver and the diaphragm. Dislodge the ribs without disturbing the lungs.</li>
	<li>With a fine pair of scissors, open the upper part of the trachea which is closer to the jugular vein.</li>
	<li>Using a catheter, inject an agent such as 1 ml of Z-fix or India ink through the trachea to fill the lungs (Figure 2A). Embed the Z-fix Lungs in paraffin.</li>
	<li>De-stain the lungs injected with India ink in Fekete&#8217;s solution (100 ml&#160;70% alcohol, 10 ml&#160;of 10% buffered formalin, and 5 ml&#160;of glacial acetic acid) for 5 min. Define tumor nodules at secondary sites with a &#8805; 0.5 mm in diameter, determine the nodules as metastasis. 
	NOTE: Due to bronchi and bronchiole blockage by the tumor, tumor nodules cannot absorb 15% India ink, and thus normal lung tissue will be in black, and tumor nodules will be in white color 7. This will allow visualization of individual tumor nodules (Figure 2B).</li>
</ol>
3. Preparing Mouse Embryonic Fibroblasts (MEFs) from Mouse Embryos
<ol>
	<li>Sacrifice pregnant mice with Isoflurane (99.9%) and spray 75% ethanol to ensure a sterile environment.</li>
	<li>Open the skin from the area of the urethral orifice to the neck with scissors and isolate the embryos from the uterus.</li>
	<li>Be careful not to disturb the embryos when opening the skin.</li>
	<li>Remove the uterine horns and rinse them in cold sterile PBS (pH 7.4).</li>
	<li>Separate the embryo from its placenta very carefully and place embryos in a 10cm plate containing ice cold PBS (pH 7.4).</li>
	<li>Remove the head, liver and gut from the embryo and place the remaining portion in a 12 well tissue culture plate containing PBS (pH 7.4).</li>
	<li>Transfer the embryo body to another 12 well plate containing trypsin EDTA and cut into small pieces (~ 1 mm3) using a sterile razor blade and scissors. Incubate the chopped material with 5 ml of trypsin EDTA for 5 min&#160;at 37 &#176;C.</li>
	<li>Inactivate trypsin by adding 1 ml Fetal Bovine Serum (FBS) to the chopped embryos. Centrifuge the suspension at 200 x g speed for 10 min, carefully remove the supernatant, resuspend the pellet with 1 ml of warm DMEM medium and transfer all the contents to a 10cm dish containing 10 ml&#160;of DMEM (with 20% FBS and 2X Penicillin/Streptomycin).</li>
	<li>Change the medium every day for two days. Culture the cells until desired cell number is attained.</li>
</ol>

<ol>
	<li>Minn, A. J., 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=Genes+that+mediate+breast+cancer+metastasis+to+lung.">Genes that mediate breast cancer metastasis to lung.</a> Natur. 436 (7050), 518-524 (2005).</li><li>Poste, G., Fidler, I. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pathogenesis+of+cancer+metastasis.">The pathogenesis of cancer metastasis.</a> Natur. 283 (5743), 139-146 (1980).</li><li>Wan, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+Metastasis+Moving+New+Biological+Insights+into+the+Clinic.">Tumor Metastasis Moving New Biological Insights into the Clinic.</a> Nat Med. 19 (11), 1450-1464 (2013).</li><li>Bergers, G., Benjamin, L. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumorigenesis+and+the+angiogenic+switch.">Tumorigenesis and the angiogenic switch.</a> Nat Rev Cancer. 3 (6), 401-410 (2003).</li><li>Frese, K. K., Tuveson, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maximizing+mouse+cancer+models.">Maximizing mouse cancer models.</a> Nat Rev Cancer. 7 (9), 654-658 (2007).</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 (3), 954-961 (1992).</li><li>Wexler, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accurate+Identification+of+Experimental+Pulmonary+Metastases.">Accurate Identification of Experimental Pulmonary Metastases.</a> J Natl Cancer Inst. 36 (4), 641-645 (1966).</li><li>Boczkowski, D., Nair, S. K., Nam, J. H., Lyerly, H. K., Gilboa, E. <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+tumor+immunity+and+cytotoxic+T+lymphocyte+responses+using+dendritic+cells+transfected+with+messenger+RNA+amplified+from+tumor+cells.">Induction of tumor immunity and cytotoxic T lymphocyte responses using dendritic cells transfected with messenger RNA amplified from tumor cells.</a> Cancer Res. 60 (4), 1028-1034 (2000).</li><li>Vargo-Gogola, T., Rosen, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modelling+breast+cancer:+one+size+does+not+fit+all.">Modelling breast cancer: one size does not fit all.</a> Nat Rev Cancer. 7 (9), 659-672 (2007).</li><li>Watts, A. M., Kennedy, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitation+of+Tumor+Foci+in+an+Experimental+Murine+Tumor+Model+Using+Computer-Assisted+Video+Imaging.">Quantitation of Tumor Foci in an Experimental Murine Tumor Model Using Computer-Assisted Video Imaging.</a> Anal Bioche. 256 (2), 217-219 (1998).</li><li>Rosenberg, S. 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=Regression+of+Established+Pulmonary+Metastases+and+Subcutaneous+Tumor+Mediated+by+the+Systemic+Administration+of+High-Dose+Recombinant+Interleukin+2.">Regression of Established Pulmonary Metastases and Subcutaneous Tumor Mediated by the Systemic Administration of High-Dose Recombinant Interleukin 2.</a> J Exp Me. 161 (5), 1169-1188 (1985).</li><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 Re. 8 (4), 212 (2006).</li><li>Veer, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+expression+profiling+predicts+clinical+outcome+of+breast+cancer.">Gene expression profiling predicts clinical outcome of breast cancer.</a> Nature. 415 (6871), 530-536 (2002).</li></ol>

The authors have no disclosures.

This protocol is for isolating primary cells from a fresh mouse tumor. Lysates prepared from this method are useful for protein, DNA and RNA analysis. Cancerous cells from the primary breast tumor often metastasize to the brain, lung and bone 1. Included is a technique to extract the lung for detection of metastasis. Staining the lung with an ink stain will allow for the visualization of tumor nodules as seen in Figure 2B. Fixing the lungs in Z-fix solution will allow us to make sections of lungs, and stain with antibodies that are appropriate to study metastatic mechanisms. Also included is a protocol for the isolation of mouse embryonic fibroblasts. This is useful for comparing the gene expression of the primary tumor cells with the embryonic fibroblast in the same animal type.
In the preparation of primary cells and MEFs, the most critical step is the mincing of the material. Without proper breakdown, low cell number will be achieved. If a low cell count is achieved, protocol can still be followed, but the cells will need to be cultured for a longer period of time.. In the lung extraction, proper staining and destaining is essential to allow for tumor nodule visualization. To extract RNA/protein from lungs, it will be good to use lungs that are unstained and unfixed. However, RNA can be extracted from fixed tissues as well 8.
Since the metastatic stage of breast cancer poses the greatest threat to the affected individual 2, it is important to visualize all components of breast tumorigenesis. A major challenge in understanding mechanisms of breast cancer progression is the availability of models that recapitulate the progression of the disease 9. Elucidation of the molecular mechanisms of breast tumorigenesis and metastasis are achieved by using animal models, such as mice 9, 10. The most common ways to induce mouse mammary tumors are genetically engineer the mice with pre-disposing mutations of oncogenes or tumor suppressors, introducing carcinogens, and injecting highly invasive cancer cells 10-12. Obtained tumors can then be further analyzed for gene expression. For breast cancer research, gene expression profiling is important since it predicts the clinical outcome of the patient 13.
Some limitations exist with the mouse model of studying mammary tumorigenesis. Although mice share molecular and physiological similarities with humans, they do not always recapitulate all aspects of human diseases5. This should be taken into consideration when using certain genetically engineered mice. Overall, mouse models provide a more realistic way to analyze mouse mammary tumorigenesis over other present models such as tissue culture and isolated human tumors. Taken together, this protocol allows for the further investigation of different aspects of breast tumorigenesis.

Metastasis is the final step in the progression of breast cancer 1. It involves a series of steps in which malignant cells are released from the primary tumor and disseminated to other organs 2. The cells must be able to intravasate, survive in circulation, extravasate to distant organs, and survive in that new organ system 3. Each step in tumorigenesis is tightly controlled by cells through various genetic and epigenetic changes 4. To study the mechanisms of breast cancer tumorigenesis, mouse model systems have been utilized due to their short lifespan, small size and fast breeding time. Some major advantages of using mouse models in cancer research are the molecular and physiological similarities they share with humans 5. 
Established mouse and human cell lines have been used extensively in breast cancer research. Although we can obtain some information about the steps in metastasis using these cells, genetically manipulated animal models with tumor suppressors/oncogenes will give far more information about tumor development and metastasis starting from the embryonic stage. Thus, with these mouse models, we can obtain genetic and developmental regulation of tumor growth. Furthermore, the tumor microenvironment also plays an important role in tumor cell gene expression and it can be difficult to mimic the same scenario with studies using established cell lines. Primary human mammary tumors can also be used to study mouse mammary tumorigenesis. The main disadvantage of using isolated breast tumors is that this newly implanted tumor does not have the mouse&#8217;s vasculature and lymphatic tissue. Whereas the genetic mouse model systems for studying mammary tumorigenesis will allow us to monitor the steps of metastasis, analyze the tumor microenvironment, and access to the entire body 5.
The overall goal of this protocol is to study breast tumorigenesis in mice. It is known that breast cancers typically metastasize to the brain, lung and bone. This protocol allows for the isolation of primary mammary tumor cells, as well as, studying breast cancer metastasis to the lung. Furthermore, another protocol for analyzing mouse embryonic fibroblasts (MEFs) from the mouse embryo is included. Together, these techniques are useful in studying mouse mammary tumorigenesis.

<table><tbody><tr><td>DMEM</td><td>HyClone</td><td>SH30243.01</td><td>Store at 4 &amp;deg;C</td></tr><tr><td>0.05% Trypsin-EDTA</td><td>Life&amp;nbsp; technologies</td><td>25300-062</td><td>Store at &amp;ndash; 20 &amp;deg;C</td></tr><tr><td>Collagenase Type IV</td><td>Sigma-Aldrich</td><td>C5138</td><td>Store at &amp;ndash; 20 &amp;deg;C</td></tr><tr><td>Hyaluronidase</td><td>Sigma-Aldrich</td><td>H3506</td><td>Store at &amp;ndash; 20 &amp;deg;C</td></tr><tr><td>Pen Strep</td><td>Life&amp;nbsp; technologies</td><td>15140-122</td><td>Store at 4 &amp;deg;C</td></tr><tr><td>Fetal Bovine Serum (FBS)</td><td>Gemini Bio-Products</td><td>100-106</td><td>Store at &amp;ndash; 80 &amp;deg;C</td></tr><tr><td>Z-fix</td><td>ANATECH</td><td>#174</td><td>Store at RT</td></tr><tr><td>India Ink</td><td>Yasutomo</td><td></td><td>Store at RT</td></tr><tr><td>AERRANE (Isoflurane)</td><td>Baxter</td><td>NDC 10019-773-60</td><td>Store at RT</td></tr><tr><td>Ethanol</td><td>EMD</td><td>AX0441-3</td><td>Store at RT</td></tr></tbody></table>

primary tumor and mef cell isolation to study lung metastasis

In breast tumorigenesis, the metastatic stage of the disease poses the greatest threat to the affected individual. Normal breast cells with altered genotypes now possess the ability to invade and survive in other tissues. In this protocol, mouse mammary tumors are removed and primary cells are prepared from tumors. The cells isolated from this procedure are then available for gene profiling experiments. For successful metastasis, these cells must be able to intravasate, survive in circulation, extravasate to distant organs, and survive in that new organ system. The lungs are the typical target of breast cancer metastasis. A set of genes have been discovered that mediates the selectivity of metastasis to the lung. Here we describe a method of studying lung metastasis from a genetically engineered mouse model.. Furthermore, another protocol for analyzing mouse embryonic fibroblasts (MEFs) from the mouse embryo is included. MEF cells from the same animal type provide a clue of non-cancer cell gene expression. Together, these techniques are useful in studying mouse mammary tumorigenesis, its associated signaling mechanisms and pathways of the abnormalities in embryos.

The tumor progression stage at which to sacrifice the animal depends on the particular study and IACUC guidelines. In Figure 1A, a 100 day old C57BL/6 mouse with the Mouse Mammary Tumor Virus Polyoma Middle T-Antigen (MMTV-PyMT) was sacrificed at three months. The skin was opened from the area of the urethral orifice to the neck with the scissors and the skin was pinned down to allow easy access to organs as shown in Figure 1B. This allowed easy access to the tumor that was obtained in Figure 1C. The primary cells obtained from the tumors are visualized in Figure 1D. Since many genes mediate breast cancer metastasis to the lung 1, we extracted the lungs (Figure 2A) to study the metastatic process. The lung was inflated with Z-fix and stained with India ink (Figure 2B) to visualize the tumor nodules. Figure 3 shows mouse embryonic fibroblasts isolated from FVB strain mouse embryos.
<img alt="Figure 1" src="/files/ftp_upload/52609/52609fig1.jpg" /> 
Figure 1.&#160;Preparation of Primary Cells from Breast Tumors.&#160;(A) A 100 day old female mouse with the Polyoma Middle T-Antigen (PyMT) was sacrificed. (B) The skin was pinned down to allow easy access to the mammary tumor. (C) The breast tumor was cut from the animal. (D) The isolated primary cells were cultured in Dulbecco&#8217;s Modified Eagle Medium (DMEM) supplemented with 10% fetal bovine serum and antibiotics (scale bar: 100 &#956;M). The images display the cells at day 3. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52609/52609fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/52609/52609fig2.jpg" /> 
Figure 2.&#160;Mouse lung extraction to visualize lung metastasis.&#160;(A) The lung was inflated with Z-fix and (B) stained with India ink to visualize tumor nodules (scale bar: 500 &#956;M). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52609/52609fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/52609/52609fig3.jpg" /> 
Figure 3. Preparing Mouse Embryonic Fibroblasts (MEFs) from Mouse Embryos.&#160;MEF cells were extracted from a FVB mouse embryo (scale bar: 100 &#956;M). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52609/52609fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Primary Tumor and MEF Cell Isolation to Study Lung Metastasis at JoVE.com

Primary Tumor and MEF Cell Isolation to Study Lung Metastasis

The goal of this protocol is to study breast tumorigenesis. With this technique, mouse mammary tumors are removed and primary cells are prepared from tumors. A lung extraction protocol is included for studying lung metastasis. Furthermore, another protocol for analyzing mouse embryonic fibroblasts from the mouse embryo is included.

In breast tumorigenesis, the metastatic stage of the disease poses the greatest threat to the affected individual. Normal breast cells with altered ...

primary-tumor-and-mef-cell-isolation-to-study-lung-metastasis

Nanyang Technological University

Research

JoVE Journal

Medicine

15.8K Views.  Louisiana State University Health Sciences Center. The goal of this protocol is to study breast tumorigenesis. With this technique, mouse mammary tumors are removed and primary cells are prepared from tumors. A lung extraction protocol is included for studying lung metastasis. Furthermore, another protocol for analyzing mouse embryonic fibroblasts from the mouse embryo is included.

Video: Primary Tumor and MEF Cell Isolation to Study Lung Metastasis

Lung Tumor Cell Recruitment Assay

To investigate the molecular mechanisms governing tumor metastasis, various assays using the mouse as a model animal have been proposed. Here, we demonstrate a simple assay to evaluate tumor cell extravasation or micrometastasis. In this assay, tumor cells were injected through the tail vein, and after a short period, the lungs were dissected and digested to count the accumulated labeled tumor cells. This assay skips the initial step of primary tumor invasion into the blood vessel and facilitates the study of events in the distant organ where tumor metastasis occurs. The number of cells injected into the blood vessel can be optimized to observe a limited number of metastases. It has been reported that stromal cells in the distant organ contribute to metastasis. Thus, this assay could be a useful tool to explore potential therapeutic drugs or devices for prevention of tumor metastasis.

This manuscript describes a method to quantify tumor cell accumulation in the lungs in an animal model of tumor metastasis.

To investigate the molecular mechanisms governing tumor metastasis, various assays using the mouse as a model animal have been proposed. Here, we ...

Cancer Research

Experimental Metastasis Assay

Metastasis is the leading cause of death in cancer patients. To understand the mechanism of metastasis, an experimental metastasis assay was established using immunodeficient mice. This article delineates the procedures involved in this assay, including sample preparation, intravenous injection, and culturing cells from lung metastases. Briefly, a pre-determined number of human cancer cells were prepared in vitro and directly injected into the circulation of immunodeficient mice through their tail veins. A small number of cells survive the turbulence in the circulation and grow as metastases in internal organs, such as lung. The injected mice are dissected after a certain period. The tissue distribution of metastases is determined under a dissecting microscope. The number of metastases in a specific tissue is counted and it directly correlates with the metastatic ability of the injected cancer cells. The arisen metastases are isolated and cultured in vitro as cell lines, which often show enhanced metastatic abilities than the parental line when injected again into immunodeficient mice. These highly metastatic derivatives become useful tools for identifying genes or molecular pathways that regulate metastatic progression.

This article describes the procedures of an experimental metastasis assay that is used to determine the metastatic potential of human cancer cell lines.

Metastasis is the leading cause of death in cancer patients.  To understand the mechanism of metastasis, an experimental metastasis assay was established ...

Practical Considerations in Studying Metastatic Lung Colonization in Osteosarcoma Using the Pulmonary Metastasis Assay

The pulmonary metastasis assay (PuMA) is an ex vivo lung explant and closed cell culture system that permits researchers to study the biology of lung colonization in osteosarcoma (OS) by fluorescence microscopy. This article provides a detailed description of the protocol, and discusses examples of obtaining image data on metastatic growth using widefield or confocal fluorescence microscopy platforms. The flexibility of the PuMA model permits researchers to study not only the growth of OS cells in the lung microenvironment, but also to assess the effects of anti-metastatic therapeutics over time. Confocal microscopy allows for unprecedented, high-resolution imaging of OS cell interactions with the lung parenchyma. Moreover, when the PuMA model is combined with fluorescent dyes or fluorescent protein genetic reporters, researchers can study the lung microenvironment, cellular and subcellular structures, gene function, and promoter activity in metastatic OS cells. The PuMA model provides a new tool for osteosarcoma researchers to discover new metastasis biology and assess the activity of novel anti-metastatic, targeted therapies.

The goal of this article is to provide a detailed description of the protocol for the pulmonary metastasis assay (PuMA). This model permits researchers to study metastatic osteosarcoma (OS) cell growth in lung tissue using a widefield fluorescence or confocal laser-scanning microscope.

The pulmonary metastasis assay (PuMA) is an ex vivo lung explant and closed cell culture system that permits researchers to study the biology of lung ...

The Establishment of a Lung Colonization Assay for Circulating Tumor Cell Visualization in Lung Tissues

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by CTCs critically contributes to early lung metastatic processes, has been vigorously investigated. As such, animal models are the only approach that captures the full systemic process of metastasis. Given that problems occur in previous experimental designs for examining the contributions of CTCs to blood vessel extravasation, we established an in vivo lung colonization assay in which a long-term-fluorescence cell-tracer, carboxyfluorescein succinimidyl ester (CFSE), was used to label suspended tumor cells and lung perfusion was performed to clear non-specifically trapped CTCs prior to lung removal, confocal imaging, and quantification. Polymeric fibronectin (polyFN) assembled on CTC surfaces has been found to mediate lung colonization in the final establishment of metastatic tumor tissues. Here, to specifically test the requirement of polyFN assembly on CTCs for lung colonization and extravasation, we performed short term lung colonization assays in which suspended Lewis lung carcinoma cells (LLCs) stably expressing FN-shRNA (shFN) or scramble-shRNA (shScr) and pre-labeled with 20 &#956;M of CFSE were intravenously inoculated into C57BL/6 mice. We successfully demonstrated that the abilities of shFN LLC cells to colonize the mouse lungs were significantly diminished in comparison to shScr LLC cells. Therefore, this short-term methodology may be widely applied to specifically demonstrate the ability of CTCs within the circulation to colonize the lungs.

An animal model is needed to decipher the role of circulating tumor cells (CTCs) in promoting lung colonization during cancer metastasis. Here, we established and successfully performed an in vivo assay to specifically test the requirement of polymeric fibronectin (polyFN) assembly on CTCs for lung colonization.

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by ...

Acellular and Cellular Lung Model to Study Tumor Metastasis

It is difficult to isolate tumor cells at different points of tumor progression. We created an ex vivo lung model that can show the interaction of tumor cells with a natural matrix and continual flow of nutrients, as well as a model that shows the interaction of tumor cells with normal cellular components and a natural matrix. The acellular ex vivo lung model is created by isolating a rat heart-lung block and removing all the cells using the decellularization process. The right main bronchus is tied off and tumor cells are placed in the trachea by a syringe. The cells move and populate the left lung. The lung is then placed in a bioreactor where the pulmonary artery receives a continual flow of media in a closed circuit. The tumor grown on the left lung is the primary tumor. The tumor cells that are isolated in the circulating media are circulating tumor cells and the tumor cells in the right lung are metastatic lesions. The cellular ex vivo lung model is created by skipping the decellularization process. Each model can be used to answer different research questions.

Here, we present a protocol for an ex vivo lung cancer model that mimics the steps of tumor progression and helps to isolate a primary tumor, circulating tumor cells, and metastatic lesions.

It is difficult to isolate tumor cells at different points of tumor progression. We created an ex vivo lung model that can show the interaction of tumor ...

Generation and Expansion of Primary, Malignant Pleural Mesothelioma Tumor Lines

Current methodologies for the expansion of primary tumor cell lines from rare tumor types are lacking. This protocol describes methods to expand primary tumor cells from surgically resected, malignant pleural mesothelioma (MPM) by providing a complete overview of the process from digestion to enrichment, expansion, cryopreservation, and phenotypic characterization. In addition, this protocol introduces concepts for tumor generation that may be useful for multiple tumor types such as differential trypsinization and the impact of dissociation methods on the detection of cell surface markers for phenotypic characterization. The major limitation of this study is the selection of tumor cells that will expand in a two-dimensional (2D) culture system. Variations to this protocol, including three-dimensional (3D) culture systems, media supplements, plate coating to improve adhesion, and alternate disaggregation methods, could improve this technique and the overall success rate of establishing a tumor line. Overall, this protocol provides a base method for establishing and characterizing tumor cells from this rare tumor.

The goal of this method paper is to demonstrate a robust and reproducible methodology for the enrichment, generation, and expansion of primary tumor cell lines from surgically resected pleural mesothelioma.

Current methodologies for the expansion of primary tumor cell lines from rare tumor types are lacking. This protocol describes methods to expand primary ...

Examining Tumor Cell Dissemination from Lung Metastases

Tracking Tumor Cell Dissemination from Lung Metastases Using Photoconversion

Metastasis - the systemic spread of cancer - is the leading cause of cancer-related deaths. Although metastasis is commonly thought of as a unidirectional process wherein cells from the primary tumor disseminate and seed metastases, tumor cells in existing metastases can also redisseminate and give rise to new lesions in tertiary sites in a process known as &#34;metastasis-from-metastases&#34; or &#34;metastasis-to-metastasis seeding.&#34; Metastasis-to-metastasis seeding may increase the metastatic burden and decrease the patient&#39;s quality of life and survival. Therefore, understanding the processes behind this phenomenon is crucial to refining treatment strategies for patients with metastatic cancer.
Little is known about metastasis-to-metastasis seeding, due in part to logistical and technological limitations. Studies on metastasis-to-metastasis seeding rely primarily on sequencing methods, which may not be practical for researchers studying the exact timing of metastasis-to-metastasis seeding events or what promotes or prevents them. This highlights the lack of methodologies that facilitate the study of metastasis-to-metastasis seeding. To address this, we have developed - and describe herein - a murine surgical protocol for the selective photoconversion of lung metastases, allowing specific marking and fate tracking of tumor cells redisseminating from the lung to tertiary sites. To our knowledge, this is the only method for studying tumor cell redissemination and metastasis-to-metastasis seeding from the lungs that does not require genomic analysis.

Author Spotlight: Decoding Metastasis-to-Metastasis Seeding Using a New In Vivo Technique for Tracking Breast Cancer Spread 

We present a method for studying tumor cell redissemination from lung metastases involving a surgical protocol for the selective photoconversion of lung metastases, followed by the identification of redisseminated tumor cells in tertiary organs.

Metastasis - the systemic spread of cancer - is the leading cause of cancer-related deaths. Although metastasis is commonly thought of as a unidirectional ...

Isolation and Characterization of Neutrophils with Anti-Tumor Properties

Neutrophils, the most abundant of all white blood cells in the human circulation, play an important role in the host defense against invading microorganisms. In addition, neutrophils play a central role in the immune surveillance of tumor cells. They have the ability to recognize tumor cells and induce tumor cell death either through a cell contact-dependent mechanism involving hydrogen peroxide or through antibody-dependent cell-mediated cytotoxicity (ADCC). Neutrophils with anti-tumor activity can be isolated from peripheral blood of cancer patients and of tumor-bearing mice. These neutrophils are termed tumor-entrained neutrophils (TEN) to distinguish them from neutrophils of healthy subjects or na&#239;ve mice that show no significant tumor cytotoxic activity. Compared with other white blood cells, neutrophils show different buoyancy making it feasible to obtain a &#62; 98% pure neutrophil population when subjected to a density gradient. However, in addition to the normal high-density neutrophil population (HDN), in cancer patients, in tumor-bearing mice, as well as under chronic inflammatory conditions, distinct low-density neutrophil populations (LDN) appear in the circulation. LDN co-purify with the mononuclear fraction and can be separated from mononuclear cells using either positive or negative selection strategies. Once the purity of the isolated neutrophils is determined by flow cytometry, they can be used for in vitro and in vivo functional assays. We describe techniques for monitoring the anti-tumor activity of neutrophils, their ability to migrate and to produce reactive oxygen species, as well as monitoring their phagocytic capacity ex vivo. We further describe techniques to label the neutrophils for in vivo tracking, and to determine their anti-metastatic capacity in vivo. All these techniques are essential for understanding how to obtain and characterize neutrophils with anti-tumor function.

Neutrophils play an important role not only in host defense against invading microorganisms, but are also involved in the immune surveillance of tumor cells. Here, we describe techniques related to the isolation of neutrophils with anti-tumor properties and methods for monitoring anti-tumor neutrophil function in vitro and in vivo.

Neutrophils, the most abundant of all white blood cells in the human circulation, play an important role in the host defense against invading ...

Immunology and Infection

Ex vivo Live Imaging of Lung Metastasis and Their Microenvironment

Metastasis is a major cause for cancer-related morbidity and mortality. Metastasis is a multistep process and due to its complexity, the exact cellular and molecular processes that govern metastatic dissemination and growth are still elusive. Live imaging allows visualization of the dynamic and spatial interactions of cells and their microenvironment. Solid tumors commonly metastasize to the lungs. However, the anatomical location of the lungs poses a challenge to intravital imaging. This protocol provides a relatively simple and quick method for ex vivo live imaging of the dynamic interactions between tumor cells and their surrounding stroma within lung metastasis. Using this method, the motility of cancer cells as well as interactions between cancer cells and stromal cells in their microenvironment can be visualized in real time for several hours. By using transgenic fluorescent reporter mice, a fluorescent cell line, injectable fluorescently labeled molecules and/or antibodies, multiple components of the lung microenvironment can be visualized, such as blood vessels and immune cells. To image the different cell types, a spinning disk confocal microscope that allows long-term continuous imaging with rapid, four-color image acquisition has been used. Time-lapse movies compiled from images collected over multiple positions and focal planes show interactions between live metastatic and immune cells for at least 4 hr. This technique can be further used to test chemotherapy or targeted therapy. Moreover, this method could be adapted for the study of other lung-related pathologies that may affect the lung microenvironment.

Ex vivo Live Imaging of Lung Metastasis and Their Microenvironment

We describe a relatively simple method for ex vivo live imaging of the tumor cell-stroma interactions within lung metastasis, utilizing fluorescent reporters in mice. Using spinning-disk confocal microscopy, this technique enables visualization of live cells for at least 4 hr and could be adapted to study other inflammatory lung conditions.

Metastasis is a major cause for cancer-related morbidity and mortality. Metastasis is a multistep process and due to its complexity, the exact cellular ...

Injection of Syngeneic Murine Melanoma Cells to Determine Their Metastatic Potential in the Lungs

Approximately 90% of human cancer deaths are linked to metastasis. Despite the prevalence and relative harm of metastasis, therapeutics for treatment or prevention are lacking. We report a method for the establishment of pulmonary metastases in mice, useful for the study of this phenomenon. Tail vein injection of B57BL/6J mice with B16-BL6 is among the most used models for melanoma metastases. Some of the circulating tumor cells establish themselves in the lungs of the mouse, creating "experimental" metastatic foci. With this model it is possible to measure the relative effects of therapeutic agents on the development of cancer metastasis. The difference in enumerated lung foci between treated and untreated mice indicates the efficacy of metastases neutralization. However, prior to the investigation of a therapeutic agent, it is necessary to determine an optimal number of injected B16-BL6 cells for the quantitative analysis of metastatic foci. Injection of too many cells may result in an overabundance of metastatic foci, impairing proper quantification and overwhelming the effects of anti-cancer therapies, while injection of too few cells will hinder the comparison between treated and controls.

Metastasis plays a profound role in the virulence of cancer, accounting for an estimated 90% of deaths. We report a protocol for a metastatic melanoma model in mice that is useful for determining the efficacy of therapeutic agents against this clinical phenomenon.

Approximately 90% of human cancer deaths are linked to metastasis.  Despite the prevalence and relative harm of metastasis, therapeutics for treatment or ...

Primary Tumor and MEF Cell Isolation to Study Lung Metastasis

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