MB is supported by grant funding from an MRC fellowship. KP and AHM are supported by grant funding from Wessex Medical Research and Cancer Research UK/RCS (England) (C28503/A10013). We are thankful for the support of the University of Southampton Histochemistry Research Unit.

1. Establishment of Primary Fibroblast Cultures from Colonic Explants
<ol>
	<li>Obtain samples of normal human colon mucosa tissue directly from the surgical operating theatre, and suspend in 7-10 ml of PBS supplemented with 100 units/ml penicillin, 100 &#956;g/ml streptomycin, and 0.25 &#956;g/ml Fungizone.</li>
	<li>In the laboratory, place the specimen at the center of a 10-cm tissue culture dish and wash 3 times with PBS/Pen-strep/Fungizone. Do not aspirate after the final wash.</li>
	<li>With sterile forceps and scalpel, cut the tissue into small pieces (approximately 2mm) and place each piece at the center of a cross drawn with the scalpel blade in a 12-well plate. Rock the scalpel gently over the tissue to allow it to adhere.</li>
	<li>Culture the specimens in 750 &#956;l primary fibroblast growth media (DMEM supplemented with 20% fetal calf serum (FCS), 100 U/ml penicillin, 100 &#956;g/ml streptomycin and 292 &#956;g/ml L-Glutamine), which should submerge the tissue without enabling it to float. Avoid disturbing the plate over the next 5 days except to re-feed every 2 days.</li>
	<li>Over the next 5 days fibroblasts will slowly start to grow out from the edge of the tissue. At approximately 7 days, this will be more visible. After approximately 3-4 weeks, and if there are sufficient fibroblasts growing out, add 750 &#956;l trypsin to each well. After cells have detached (which may take 5-10 min), pool and transfer to a T-25 tissue culture flask.</li>
</ol>
2. Organotypic Preparation
Preparation of the fibroblast impregnated organotypic gel:
<ol>
	<li>Prepare a fibroblast cell suspension containing 5 x 105 cells per organotypic in DMEM supplemented with 10% FCS and 292 &#956;g/ml L-Glutamine.</li>
	<li>Make up the organotypic gels on ice, in the following ratios:
	<ul>
		<li>7 volumes of Rat-Tail Collagen: Matrigel mix (1:1)</li>
		<li>1 volume of filtered 10x DMEM</li>
		<li>1 volume of FCS</li>
		<li>1 volume of fibroblast cell suspension containing 5 x 105 fibroblasts 
		For 9 gels (1 ml per gel) prepare 10 ml and mix gently to avoid bubbles.</li>
	</ul>
	</li>
	<li>Add 1 ml to each well of a 24-well plate and incubate for 1 hour at 37 &#176;C in a humidified atmosphere to allow gels to set. After 1 hr add 1 ml DMEM (10% FCS)/Glut on top of the gels and return to the incubator overnight.</li>
	<li>The following day, aspirate medium from the top of the gels and plate 1ml of media containing 5 x 105 CRC epithelial cells.</li>
</ol>
Preparation of gel coated nylon sheets:
<ol start="5">
	<li>Prepare sterile, autoclaved nylon sheets measuring 1.5 cm x 1.5 cm, in advance.</li>
	<li>Using sterile forceps, place the required number of nylon sheets in a 10 cm culture dish (usually 4 nylon sheets can be accommodated per dish).</li>
	<li>Make up gel on ice in the following order (250 &#956;l total volume is required per nylon sheet):
	<ul>
		<li>7 volumes of Rat-Tail Collagen</li>
		<li>1 volume of filtered 10x DMEM</li>
		<li>1 volume of FCS</li>
		<li>1 volume of DMEM 10% FCS/Glut</li>
	</ul>
	</li>
	<li>If the solution is yellow, neutralize by adding 0.1 M NAOH in 50 &#956;l aliquots until the solution turns pink.</li>
	<li>Add 250 &#956;l of this solution to each nylon sheet and incubate at 37 &#176;C in a humidified atmosphere of 5% CO2 for 30 min to allow gel to set.</li>
	<li>Make up 1% glutaraldehyde solution in PBS. Add 10 ml to each 10 cm culture dish once the gel has set and incubate at 4&#160;&#176;C for 1 hr.</li>
	<li>Wash nylon sheets 3x in PBS and 1x in DMEM (10% FCS)/Glu and incubate overnight in DMEM/Glu at 4 &#176;C.</li>
</ol>
Raising organotypic gels onto steel grids for invasion:
<ol start="12">
	<li>Pre-prepare scaffolding grids by folding stainless steel sheets into a tripod formation. Autoclave prior to use.</li>
	<li>Use forceps sterilized in ethanol to place a steel grid into each well of a six well plate.</li>
	<li>Place a gel-coated nylon sheet with the collagen side uppermost, onto each grid.</li>
	<li>Carefully transfer the organotypic gels from the 24-well plate to the raised nylon sheet using a spatula sterilized in ethanol.</li>
	<li>Fill the well with DMEM 10% FCS/Glut supplemented with 10% FCS until the nylon sheet is in contact with the medium but not submerged. Make sure the medium does not touch the organotypic gel.</li>
	<li>Incubate for 14 days at 37 &#176;C in a humidified atmosphere of 5% CO2, replacing media every 2 days.</li>
</ol>
3. Organotypic Fixation
<ol>
	<li>Remove whole organotypic including nylon sheet from well and place on cling film.</li>
	<li>Bisect organotypic and nylon sheet using a clean disposable scalpel and fix both halves in formaldehyde for 24 hr at room temperature.</li>
	<li>Replace formaldehyde with 70% ethanol after 24 hr and leave overnight prior to embedding in paraffin, sectioning, and staining.</li>
</ol>
4. Laser Microdissection of the Invasive Margin
<ol>
	<li>Section to 10 &#956;m-thickness onto membrane mounted slides.</li>
	<li>Deparaffinize sections by applying Xylene for 1 min, then remove Xylene and fix in 75% ethanol for a further 1 min.</li>
	<li>Remove ethanol and stain with 0.125% Cresyl Violet solution for 1 min. Cresyl Violet highlights epithelial cells and permits easy discrimination from the stroma.</li>
	<li>Remove Cresyl Violet and apply 100% ethanol for a further 1 min before rinsing with 100% ethanol. Allow slides to air dry for 30 min.</li>
	<li>Conduct laser microdissection using chosen platform (e.g. the Leica AS system).</li>
	<li>Place the glass slide with the stained section to be microdissected face down on the microscope stage.</li>
	<li>Mount a 0.5 ml microcentrifuge tube into the collection cassette and add 50 &#956;l of cell lysis buffer (e.g.&#160;DNA, RNA or protein lysis buffer) to the cap into which microdissected tissue will collect.</li>
	<li>Under direct vision, use the joystick to identify tissue of interest, and using the software interface, annotate the stained organic section, highlighting cells to be microdissected at the tumor invasion front.</li>
	<li>Instruct the laser to fire, which should both cut out the highlighted section and propel microdissected tissue into the cap of the microcentrifuge tube.</li>
	<li>Once sufficient material has been collected, eject the collection cassette, close the microcentrifuge tube and spin gently to draw the lysis buffer to the bottom of the tube.</li>
	<li>Place samples on ice until microdissection is complete. Process samples by an appropriate method to extract the analyte of interest.</li>
</ol>

<ol>
	<li>Nystrom, M. L., Thomas, G. J., Stone, M., Mackenzie, I. C., Hart, I. R., Marshall, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+quantitative+method+to+analyse+tumour+cell+invasion+in+organotypic+culture.">Development of a quantitative method to analyse tumour cell invasion in organotypic culture.</a> J Pathol. 205 (4), 468-475 (2005).</li><li>Zhang, 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=miR-153+supports+colorectal+cancer+progression+via+pleiotropic+effects+that+enhance+invasion+and+chemotherapeutic+resistance.">miR-153 supports colorectal cancer progression via pleiotropic effects that enhance invasion and chemotherapeutic resistance.</a> Cancer Res. , (2013).</li><li>Bullock, M. 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=Pleiotropic+actions+of+miR-21+highlight+the+critical+role+of+deregulated+stromal+microRNAs+during+colorectal+cancer+progression.">Pleiotropic actions of miR-21 highlight the critical role of deregulated stromal microRNAs during colorectal cancer progression.</a> Cell Death Dis. 20 (4), (2013).</li><li>Jenei, V., Nystrom, M. L., Thomas, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+invasion+in+an+organotypic+model.">Measuring invasion in an organotypic model.</a> Methods Mol Biol. 769, 223-232 (2011).</li><li>De Wever, O., Demetter, P., Mareel, M., Bracke, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stromal+myofibroblasts+are+drivers+of+invasive+cancer+growth.">Stromal myofibroblasts are drivers of invasive cancer growth.</a> Int J Cancer. 123 (10), 2229-2238 (2008).</li><li>Fries, K. 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=Evidence+of+fibroblast+heterogeneity+and+the+role+of+fibroblast+subpopulations+in+fibrosis.">Evidence of fibroblast heterogeneity and the role of fibroblast subpopulations in fibrosis.</a> Clin Immunol Immunopathol. 72 (3), 283-292 (1994).</li><li>Moutasim, K. 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=Betel-derived+alkaloid+up-regulates+keratinocyte+alphavbeta6+integrin+expression+and+promotes+oral+submucous+fibrosis.">Betel-derived alkaloid up-regulates keratinocyte alphavbeta6 integrin expression and promotes oral submucous fibrosis.</a> J Pathol. 223 (3), 366-377 (2011).</li><li>Winter, J., Jung, S., Keller, S., Gregory, R. I., Diederichs, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Many+roads+to+maturity:+microRNA+biogenesis+pathways+and+their+regulation.">Many roads to maturity: microRNA biogenesis pathways and their regulation.</a> Nat Cell Biol. 11 (3), 228-234 (2009).</li><li>Li, 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=Comparison+of+miRNA+expression+patterns+using+total+RNA+extracted+from+matched+samples+of+formalin-fixed+paraffin-embedded+(FFPE)+cells+and+snap+frozen+cells.">Comparison of miRNA expression patterns using total RNA extracted from matched samples of formalin-fixed paraffin-embedded (FFPE) cells and snap frozen cells.</a> BMC Biotechnol. 7 (36), (2007).</li><li>Szafranska, A. E., 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=Accurate+molecular+characterization+of+formalin-fixed,+paraffin-embedded+tissues+by+microRNA+expression+profiling.">Accurate molecular characterization of formalin-fixed, paraffin-embedded tissues by microRNA expression profiling.</a> J Mol Diagn. 10 (5), 415-423 (2008).</li></ol>

The authors disclose no potential conflicts of interest.

Here we describe a method to specifically isolate and characterize tumor cells which have acquired the capacity to invade the cancer associated stroma during the earliest stages of metastatic progression in a 3-dimensional co-culture construct of epithelial and stromal cells.
Co-culture models comprised of CRC epithelial cells juxtaposed with a synthetic stroma containing ex&#160;vivo human colonic fibroblasts were used to study CRC invasion in 3-dimensions. This physiologically relev...

Organotypic co-cultures are tissue-engineered models which aid in reconstructing the in vivo tumor microenvironment in 3-dimensions by juxtaposing malignant epithelial cells and stromal cells in a collagen gel containing essential extracellular matrix components1-3. Principally conceived as a method of measuring tumor invasion, organotypics reduce reliance on in vivo animal models, and avoid the shortcomings of other in vitro techniques such as Transwell assays, in which invading cells are forced artificially into a mono-dispersed state2-4. The inclusion of stromal cells in these models, such as fibroblasts, reflects the essential role of the tumor microenvironment in regulating malignant invasion and metastasis3-4, however the phenotypic heterogeneity of the stroma is such that in order to maximize the physiological relevance of organotypic models, organ specific, anatomically accurate ex vivo fibroblasts should be included wherever possible3,6.
Organotypics are a versatile platform to study interactions between tumor and stromal cells and are increasingly used in novel ways to examine the impact on tumor invasion of chemical inhibitors and targeted gene alterations7,8. Studying the invasive tumor margin is a particularly exciting prospect. In organotypic models, established colorectal cancer (CRC) cell lines typically produce a well stratified epithelial layer, and in cross section, cells that have acquired the capacity to invade the extracellular matrix (ECM) are easily discernible. In light of the established micro-topographic heterogeneity of tumor and tumor associated stromal cells in vivo, extracting these cells using Laser microdissection and studying them in isolation, may reveal important biological insights regarding the origins of colorectal cancer metastasis and how it may be more efficiently targeted. In the following methodology, all patients who donated tissue samples provided written informed consent, and the study was approved by the institutions regional research ethics committee.

<table border="0" cellpadding="0" cellspacing="0" width="634">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Colorectal cancer cell lines - example shown SW480</td>
			<td style="width:132px;">ATCC</td>
			<td style="width:119px;">ATCC CCL-228</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Collagen</td>
			<td style="width:132px;">BD Biosciences</td>
			<td style="width:119px;">354265</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Matrigel</td>
			<td style="width:132px;">BD Biosciences</td>
			<td style="width:119px;">354234</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Nylon membrane</td>
			<td style="width:132px;">Merck Millipore</td>
			<td style="width:119px;">VVLP01300</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Metal grid</td>
			<td style="width:132px;">The Mesh Company</td>
			<td>WSS20-A4</td>
			<td>themeshcompany.com</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Laser microdissection platform</td>
			<td style="width:132px;">Leica Microsystems</td>
			<td style="width:119px;">Leica AS LMD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Membrane mounted slides</td>
			<td style="width:132px;">Molecular devices</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cresyl Violet</td>
			<td style="width:132px;">Merck Millipore</td>
			<td style="width:119px;">1052350025</td>
			<td></td>
		</tr>
	</tbody>
</table>

molecular profiling of the invasive tumor microenvironment in a 3-dimensional model of colorectal cancer cells and ex vivo fibroblasts

Invading colorectal cancer (CRC) cells have acquired the capacity to break free from their sister cells, infiltrate the stroma, and remodel the extracellular matrix (ECM). Characterizing the biology of this phenotypically distinct group of cells could substantially improve our understanding of early events during the metastatic cascade.

Tumor invasion is a dynamic process facilitated by bidirectional interactions between malignant epithelium and the cancer associated stroma. In order to examine cell-specific responses at the tumor stroma-interface we have combined organotypic co-culture and laser micro-dissection techniques.
Organotypic models, in which key stromal constituents such as fibroblasts are 3-dimentioanally co-cultured with cancer epithelial cells, are highly manipulatable experimental tools which enable invasion and cancer-stroma interactions to be studied in near-physiological conditions.

Laser microdissection (LMD) is a technique which entails the surgical dissection and extraction of the various strata within tumor tissue, with micron level precision.
By combining these techniques with genomic, transcriptomic and epigenetic profiling we aim to develop a deeper understanding of the molecular characteristics of invading tumor cells and surrounding stromal tissue, and in doing so potentially reveal novel biomarkers and opportunities for drug development in CRC.&#160;&#160;&#160;

We have applied the above method to multiple combinations of CRC cell lines and stromal cells. One example presented here is SW480 epithelial CRC cell lines with primary human ex&#160;vivo colonic fibroblasts. 3-dimensional co-cultures are constructed (Figure 1), subjected to microscopy and laser capture microdissection (Figure 2), and analyzed by microRNA (miRNA) profiling (Figure 3) for comparison of differentially expressed miRNAs between cells at the invasiv...

Watch this Scientific Journal Video about Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and Ex vivo Fibroblasts at JoVE.com

Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and Ex vivo Fibroblasts

Molecular profiling of laser microdissected cells and stroma from synthetic, tissue-engineered colorectal cancer models represents a novel and manipulatable approach to characterize and dissect the distinctive biology at the interface between tumor cells at the invasive front and cancer associated stromal cells. &#160;

Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and Ex vivo Fibroblasts

Invading colorectal cancer (CRC) cells have acquired the capacity to break free from their sister cells, infiltrate the stroma, and remodel the ...

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11.0K Views.  University of Southampton School of Medicine. Molecular profiling of laser microdissected cells and stroma from synthetic, tissue-engineered colorectal cancer models represents a novel and manipulatable approach to characterize and dissect the distinctive biology at the interface between tumor cells at the invasive front and cancer associated stromal cells.  

Video: Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and Ex vivo Fibroblasts

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 ...

Modeling and Imaging 3-Dimensional Collective Cell Invasion

A defining characteristic of cancer malignancy is invasion and metastasis 1. In some cancers (e.g. glioma 2), local invasion into surrounding healthy tissue is the root cause of disease and death. For other cancers (e.g. breast, lung, etc.), it is the process of metastasis, in which tumor cells move from a primary tumor mass, colonize distal sites and ultimately contribute to organ failure, that eventually leads to morbidity and mortality 3. It has been estimated that invasion and metastasis are responsible for 90&#37; of cancer deaths 4. As a result, there has been intense interest in identifying the molecular processes and critical protein mediators of invasion and metastasis for the purposes of improving diagnosis and treatment 5.
A challenge for cancer scientists is to develop invasion assays that sufficiently resemble the in vivo situation to enable accurate disease modeling 6. Two-dimensional cell motility assays are only informative about one aspect of invasion and do not take into account extracellular matrix (ECM) protein remodeling which is also a critical element. Recently, research has refined our understanding of tumor cell invasion and revealed that individual cells may move by elongated or rounded modes 7. In addition, there has been greater appreciation of the contribution of collective invasion, in which cells invade in strands, sheets and clusters, particularly in highly differentiated tumors that maintain epithelial characteristics, to the spread of cancer 8.
We present a refined method 9 for examining the contributions of candidate proteins to collective invasion 10. In particular, by engineering separate pools of cells to express different fluorescent proteins, it is possible to molecularly dissect the activities and proteins required in leading cells versus those required in following cells. The use of RNAi provides the molecular tool to experimentally disassemble the processes involved in individual cell invasion as well as in different positions of collective invasion. In this procedure, mixtures of fluorescently-labeled cells are plated on the bottom of a Transwell insert previously filled with Matrigel ECM protein, then allowed to invade "upwards" through the filter and into the Matrigel. Reconstruction of z-series image stacks, obtained by confocal imaging, into three-dimensional representations allows for visualization of collectively invading strands and analysis of the representation of fluorescently-labeled cells in leading versus following positions.

Models of tumor cell invasion into three-dimensional extracellular matrix better reflect the in vivo situation than two-dimensional motility assays. Using matrix invasion assays combined with confocal imaging of fluorescently-labeled cells, detailed information on invasion modes and the distinct contributions of leading versus following cells can be obtained.

A defining characteristic of cancer malignancy is invasion and metastasis 1. In some cancers (e.g. glioma 2), local invasion into surrounding healthy ...

Screening for Melanoma Modifiers using a Zebrafish Autochthonous Tumor Model

Genomic studies of human cancers have yielded a wealth of information about genes that are altered in tumors1,2,3. A challenge arising from these studies is that many genes are altered, and it can be difficult to distinguish genetic alterations that drove tumorigenesis from that those arose incidentally during transformation. To draw this distinction it is beneficial to have an assay that can quantitatively measure the effect of an altered gene on tumor initiation and other processes that enable tumors to persist and disseminate. Here we present a rapid means to screen large numbers of candidate melanoma modifiers in zebrafish using an autochthonous tumor model4 that encompasses steps required for melanoma initiation and maintenance. A key reagent in this assay is the miniCoopR vector, which couples a wild-type copy of the mitfa melanocyte specification factor to a Gateway recombination cassette into which candidate melanoma genes can be recombined5. The miniCoopR vector has a mitfa rescuing minigene which contains the promoter, open reading frame and 3'-untranslated region of the wild-type mitfa gene. It allows us to make constructs using full-length open reading frames of candidate melanoma modifiers. These individual clones can then be injected into single cell Tg(mitfa:BRAFV600E);p53(lf);mitfa(lf)zebrafish embryos. The miniCoopR vector gets integrated by Tol2-mediated transgenesis6 and rescues melanocytes. Because they are physically coupled to the mitfa rescuing minigene, candidate genes are expressed in rescued melanocytes, some of which will transform and develop into tumors. The effect of a candidate gene on melanoma initiation and melanoma cell properties can be measured using melanoma-free survival curves, invasion assays, antibody staining and transplantation assays.

A rapid way to screen for melanoma modifiers using a zebrafish autochthonous tumor model is presented. It takes advantage of the miniCoopR vector which allows for expression of candidate melanoma genes in melanocytes. A method to obtain melanoma-free survival curves, an invasion assay, a protocol for antibody staining of scale melanocytes and a melanoma transplantation assay are described.

Genomic studies of  human cancers have yielded a wealth of information about genes that are altered  in tumors1,2,3. A challenge arising from these ...

Live Imaging of Drug Responses in the Tumor Microenvironment in Mouse Models of Breast Cancer

The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional co-culture systems are frequently used to explicate tumor-stroma interactions, including their role in drug responses. However, many of the interactions that occur in vivo in the intact microenvironment cannot be completely replicated in these in vitro settings. Thus, direct visualization of these processes in real-time has become an important tool in understanding tumor responses to therapies and identifying the interactions between cancer cells and the stroma that can influence these responses. Here we provide a method for using spinning disk confocal microscopy of live, anesthetized mice to directly observe drug distribution, cancer cell responses and changes in tumor-stroma interactions following administration of systemic therapy in breast cancer models. We describe procedures for labeling different tumor components, treatment of animals for observing therapeutic responses, and the surgical procedure for exposing tumor tissues for imaging up to 40 hours. The results obtained from this protocol are time-lapse movies, in which such processes as drug infiltration, cancer cell death and stromal cell migration can be evaluated using image analysis software.

We describe a method for imaging response to anti-cancer treatment in vivo and at single cell resolution.

The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional ...

Initiation of Metastatic Breast Carcinoma by Targeting of the Ductal Epithelium with Adenovirus-Cre: A Novel Transgenic Mouse Model of Breast Cancer

Breast cancer is a heterogeneous disease involving complex cellular interactions between the developing tumor and immune system, eventually resulting in exponential tumor growth and metastasis to distal tissues and the collapse of anti-tumor immunity. Many useful animal models exist to study breast cancer, but none completely recapitulate the disease progression that occurs in humans. In order to gain a better understanding of the cellular interactions that result in the formation of latent metastasis and decreased survival, we have generated an inducible transgenic mouse model of YFP-expressing ductal carcinoma that develops after sexual maturity in immune-competent mice and is driven by consistent, endocrine-independent oncogene expression. Activation of YFP, ablation of p53, and expression of an oncogenic form of K-ras was achieved by the delivery of an adenovirus expressing Cre-recombinase into the mammary duct of sexually mature, virgin female mice. Tumors begin to appear 6 weeks after the initiation of oncogenic events. After tumors become apparent, they progress slowly for approximately two weeks before they begin to grow exponentially. After 7-8 weeks post-adenovirus injection, vasculature is observed connecting the tumor mass to distal lymph nodes, with eventual lymphovascular invasion of YFP+ tumor cells to the distal axillary lymph nodes. Infiltrating leukocyte populations are similar to those found in human breast carcinomas, including the presence of &#945;&#946; and &#947;&#948; T cells, macrophages and MDSCs. This unique model will facilitate the study of cellular and immunological mechanisms involved in latent metastasis and dormancy in addition to being useful for designing novel immunotherapeutic interventions to treat invasive breast cancer.

Activation of latent mutations with adenovirus-Cre into the mammary ductal system results in a clinically relevant metastatic breast cancer. Incorporation of a YFP promoter allows tracking of distal metastatic tumor cells. This model is useful to study latent metastasis, anti-tumor immunity, and for designing novel immunotherapies to treat breast cancer.

Breast cancer is a heterogeneous disease involving complex cellular interactions between the developing tumor and immune system, eventually resulting in ...

An Ex vivo Model to Study Hormone Action in the Human Breast

The study of hormone action in the human breast has been hampered by lack of adequate model systems. Upon in vitro culture, primary mammary epithelial cells tend to lose hormone receptor expression. Widely used hormone receptor positive breast cancer cell lines are of limited relevance to the in vivo situation. Here, we describe an ex vivo model to study hormone action in the human breast. Fresh human breast tissue specimens from surgical discard material such as reduction mammoplasties or mammectomies are mechanically and enzymatically digested to obtain tissue fragments containing ducts and lobules and multiple stromal cell types. These tissue microstructures kept in basal medium without growth factors preserve their intercellular contacts, the tissue architecture, and remain hormone responsive for several days. They are readily processed for RNA and protein extraction, histological analysis or stored in freezing medium. Fluorescence activated cell sorting (FACS) can be used to enrich for specific cell populations. This protocol provides a straightforward, standard approach for translational studies with highly complex, varied human specimens.

An Ex vivo Model to Study Hormone Action in the Human Breast

We have developed a novel ex vivo model to study hormone action in the human breast. It is based on tissue microstructures isolated from surgical breast tissue specimens which preserve tissue architecture, intercellular interactions, and paracrine signaling.

The study of hormone action in the human breast has been hampered by lack of adequate model systems. Upon in vitro culture, primary mammary epithelial ...

Three-Dimensional (3D) Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in particular (e.g., brain tumors such as glioblastoma multiforme and squamous cell carcinoma of the head and neck &#8211; SCCHN) it is a cause of severe morbidity and can be life-threatening even in the absence of distant metastases. In addition, cancers which have relapsed following treatment unfortunately often present with a more aggressive phenotype. Therefore, there is an opportunity to target the process of invasion to provide novel therapies that could be complementary to standard anti-proliferative agents. Until now, this strategy has been hampered by the lack of robust, reproducible assays suitable for a detailed analysis of invasion and for drug screening. Here we provide a simple micro-plate method (based on uniform, self-assembling 3D tumor spheroids) which has great potential for such studies. We exemplify the assay platform using a human glioblastoma cell line and also an SCCHN model where the development of resistance against targeted epidermal growth factor receptor (EGFR) inhibitors is associated with enhanced matrix-invasive potential. We also provide two alternative methods of semi-automated quantification: one using an imaging cytometer and a second which simply requires standard microscopy and image capture with digital image analysis.

Three-Dimensional 3D Tumor Spheroid Invasion Assay

Invasion of surrounding normal tissues is a defining characteristic of malignant tumors. We provide here a simple, semi-automated micro-plate assay of invasion into a natural 3D biomatrix that has been exemplified with a number of models of advanced human cancers.

Invasion of surrounding normal tissues is generally considered to be a key hallmark of malignant (as opposed to benign) tumors. For some cancers in ...

Studying Pancreatic Cancer Stem Cell Characteristics for Developing New Treatment Strategies

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor initiation, metastasis and resistance to radio- and chemotherapy. Here we describe a specific methodology for culturing primary human pancreatic CSCs as tumor spheres in anchorage-independent conditions. Cells are grown in serum-free, non-adherent conditions in order to enrich for CSCs while their more differentiated progenies do not survive and proliferate during the initial phase following seeding of single cells. This assay can be used to estimate the percentage of CSCs present in a population of tumor cells. Both size (which can range from 35 to 250 micrometers) and number of tumor spheres formed represents CSC activity harbored in either bulk populations of cultured cancer cells or freshly harvested and digested tumors 1,2. Using this assay, we recently found that metformin selectively ablates pancreatic CSCs; a finding that was subsequently further corroborated by demonstrating diminished expression of pluripotency-associated genes/surface markers and reduced in vivo tumorigenicity of metformin-treated cells. As the final step for preclinical development we treated mice bearing established tumors with metformin and found significantly prolonged survival. Clinical studies testing the use of metformin in patients with PDAC are currently underway (e.g., NCT01210911, NCT01167738, and NCT01488552). Mechanistically, we found that metformin induces a fatal energy crisis in CSCs by enhancing reactive oxygen species (ROS) production and reducing mitochondrial transmembrane potential. In contrast, non-CSCs were not eliminated by metformin treatment, but rather underwent reversible cell cycle arrest. Therefore, our study serves as a successful example for the potential of in vitro sphere formation as a screening tool to identify compounds that potentially target CSCs, but this technique will require further in vitro and in vivo validation to eliminate false discoveries.

Pancreatic cancer stem cells (CSCs) can be expanded in vitro using the anchorage-independent sphere culture technique, which represents a powerful tool to study CSC biology and can serve as the first step to develop novel CSC-targeting therapies. Here the methodology for expanding, analyzing and targeting of pancreatic CSCs is provided.

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor ...

Isolation and Propagation of Circulating Tumor Cells from a Mouse Cancer Model

Cancer metastasis is the foremost cause of cancer-associated deaths. Recent studies have shown that circulating tumor cells (CTCs) are important in cancer metastasis. Indeed, the number of CTCs correlates with tumor size. Here, a detailed description is provided of a methodology for isolation and propagation of CTCs from a syngeneic mouse model of hepatocellular carcinoma (HCC) which allows for downstream analysis of potentially important molecular mechanisms of solid organ tumor metastasis. This method is efficient and reproducible. It is a non-invasive technique and, therefore, has potential to replace the invasive biopsy of tissues from humans which may be associated with complications. Therefore, the method discussed here allows for the isolation and propagation of CTCs from whole blood samples such that they can be examined and characterized. This has potential for future adaptation for clinical applications such as diagnosis, and personalized targeted therapy.

Circulating tumor cells (CTCs) have been shown to play an important role in tumor metastasis. Here, a method for the isolation and propagation of CTCs from the whole blood of a syngeneic mouse tumor model of hepatocellular carcinoma (HCC) metastasis is described.

Cancer metastasis is the foremost cause of cancer-associated deaths. Recent studies have shown that circulating tumor cells (CTCs) are important in cancer ...

A Brain Tumor/Organotypic Slice Co-culture System for Studying Tumor Microenvironment and Targeted Drug Therapies

Brain tumors are a major cause of cancer-related morbidity and mortality. Developing new therapeutics for these cancers is difficult, as many of these tumors are not easily grown in standard culture conditions. Neurosphere cultures under serum-free conditions and orthotopic xenografts have expanded the range of tumors that can be maintained. However, many types of brain tumors remain difficult to propagate or study. This is particularly true for pediatric brain tumors such as pilocytic astrocytomas and medulloblastomas. This protocol describes a system that allows primary human brain tumors to be grown in culture. This quantitative assay can be used to investigate the effect of microenvironment on tumor growth, and to test new drug therapies. This protocol describes a system where fluorescently labeled brain tumor cells are grown on an organotypic brain slice from a juvenile mouse. The response of tumor cells to drug treatments can be studied in this assay, by analyzing changes in the number of cells on the slice over time. In addition, this system can address the nature of the microenvironment that normally fosters growth of brain tumors. This brain tumor organotypic slice co-culture assay provides a propitious system for testing new drugs on human tumor cells within a brain microenvironment.

Many types of human brain tumors are localized to specific regions within the brain and are difficult to grow in culture. This protocol addresses the role of tumor microenvironment and investigates new drug treatments by analyzing fluorescent primary brain tumor cells growing in an organotypic mouse brain slice. &#160;

Brain tumors are a major cause of cancer-related morbidity and mortality. Developing new therapeutics for these cancers is difficult, as many of these ...