Name: using the dot assay to analyze migration of cell sheets
Uploaded: 2017-12-05T13:00:00
Description: Watch this Scientific Journal Video about Using the Dot Assay to Analyze Migration of Cell Sheets at JoVE.com

The author wishes to thank Bhagawat Subramanian, Yi (Jason) Chang, Paul Randazzo, and Carole Parent for reading and commenting on the manuscript. This work was supported by the Intramural Research Program of the National Cancer Institute, National Institutes of Health.

1. Coating of Dishes (Day 1)
NOTE: Make sure not to leave fingerprints or dirt on the bottom of the plate when handling it.
<ol>
	<li>Thaw mouse collagen IV on ice, and dilute it with 50 mM HCl (pH 1.3) to prepare 3 mL of a 10 &#181;g/mL collagen IV solution. 
	NOTE: Collagen will precipitate at 37 &#176;C. It is therefore important to keep the collagen solution at a low temperature while thawing and working with it. Avoid repeated freeze-thaw cycles by preparing appropriately sized aliquots and storing the...

<ol>
	<li>Liang, C. -. C., Park, A. Y., Guan, J. -. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+scratch+assay:+a+convenient+and+inexpensive+method+for+analysis+of+cell+migration+in+vitro.">In vitro scratch assay: a convenient and inexpensive method for analysis of cell migration in vitro.</a> Nat Protoc. 2 (2), 329-333 (2007).</li><li>Peplow, P. V., Chatterjee, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+the+influence+of+growth+factors+and+cytokines+in+in+vitro+human+keratinocyte+migration.">A review of the influence of growth factors and cytokines in in vitro human keratinocyte migration.</a> Cytokine. 62 (1), 1-21 (2013).</li><li>Hulkower, K. I., Herber, R. 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L., HGF, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LPA,+HGF,+and+EGF+utilize+distinct+combinations+of+signaling+pathways+to+promote+migration+and+invasion+of+MDA-MB-231+breast+carcinoma+cells.">LPA, HGF, and EGF utilize distinct combinations of signaling pathways to promote migration and invasion of MDA-MB-231 breast carcinoma cells.</a> BMC Cancer. 13, 501 (2013).</li><li>Santner, S. J., Dawson, P. 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=Malignant+MCF10CA1+cell+lines+derived+from+premalignant+human+breast+epithelial+MCF10AT+cells.">Malignant MCF10CA1 cell lines derived from premalignant human breast epithelial MCF10AT cells.</a> Breast Cancer Research and Treatment. 65 (2), 101-110 (2001).</li><li>Tang, B., Vu, 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=TGF-beta+switches+from+tumor+suppressor+to+prometastatic+factor+in+a+model+of+breast+cancer+progression.">TGF-beta switches from tumor suppressor to prometastatic factor in a model of breast cancer progression.</a> J Clin Invest. 112 (7), 1116-1124 (2003).</li><li>Lee, R. M., Stuelten, C. H., Parent, C. 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During tumor progression cells migrate away from the tissue of origin to invade the surrounding tissue and metastasize to distant sites15. Migration of cells away from a cell colony can be observed in the dot assay. Here, the dot assay is illustrated by analyzing the migratory phenotype of human breast cancer cells in response to EGF.
To obtain accurate and replicable results several steps in the set-up of the dot assays are critical. First, the coating of the plate det...

Migration assays are widely used to evaluate the invasive and metastatic potential of tumor cells in vitro. Most commonly, the wound or scratch assay is used to assess migration of epithelial sheets into a cell cleared area1,2,3. To perform the scratch assay, cells are plated into a monolayer and a &#34;scratch&#34; or cell-free area is created with a pipette tip. The scratch assay is easy to set up with commonly available tissue culture supplies and can be performed in multi-well plates, allowing for processing of multiple samples. However, as the scratch is made, cells are physically removed from the monolayer and often undergo cell death. Furthermore, extracellular matrix attached to the plate is often damaged during the scratching process. Similarly, the use of silicon inserts (such as Ibidi chambers4) or of stencils5,6,7 can lead to mechanical disruption of the cells and the partial removal of matrix proteins used for coating the plates. Another disadvantage of assays monitoring closure of wounds or scratches is their limited time course, as cell migration can only be analyzed until the scratch is closed.
In performing the dot assay, cells are plated as a circular colony onto a coated or uncoated plate8. The rationale for this plating strategy is to obtain cell sheets with defined edges, that can migrate or invade into the surrounding cell-free areas without disturbing the culture by removal of cells or inserts. The overall goal of the dot assay is to observe migration of cell sheets as measured by edge displacement or colony diameter, as well as to perform time-lapse imaging to analyze the migratory phenotype of cells in higher spatio-temporal resolution.
Cell migration can be affected by a variety of microenvironmental cues like chemokines, cytokines, and growth factors such as EGF.&#160;EGF is a growth factor that exerts its biological effects via binding to its receptor, EGF receptor9, and increases invasive and metastatic behavior of tumor cells4,9,10. Here, the dot assay is used to study EGF stimulated cell migration in a human invasive, lung colony forming breast cancer cell line (MCF10CA1a)8,11,12.

<table style="border-collapse:collapse;width:659pt" width="878">
	<colgroup>
		<col style="width:302pt" width="402" />
		<col style="width:160pt" width="213" />
		<col style="width:131pt" width="175" />
		<col style="width:66pt" width="88" />
	</colgroup>
	<tbody>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="width:302pt;height:15.75pt" width="402">MCF10CA1a cells</td>
			<td style="width:160pt" width="213">Karmanos Research Institute</td>
			<td class="xl18" style="width:131pt" width="175">N/A</td>
			<td style="width:66pt" width="88">cells used for asay</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">mouse collagen IV</td>
			<td>BD Biosciences</td>
			<td class="xl18">354233</td>
			<td>used to coat plates</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">trypsin / EDTA</td>
			<td>Thermo Fisher</td>
			<td class="xl19">25300054</td>
			<td>used to remove cells from tissue culture plates</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">DPBS&#160;</td>
			<td>Mediatech</td>
			<td class="xl18">21-031-CV</td>
			<td>used to wash cells</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">DMEM / F12</td>
			<td>Thermo Fisher</td>
			<td class="xl18">11320082</td>
			<td>used as culture medium</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">horse serum</td>
			<td>Thermo Fisher</td>
			<td class="xl18">26050088</td>
			<td>used to supplement culture medium</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">12well glass bottom plate</td>
			<td>MatTek</td>
			<td class="xl18">P12G-1.5-14-F</td>
			<td>used to grow cells for imaging</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">LPA (1-Oleoyl Lysophosphatidic Acid )</td>
			<td>Cayman</td>
			<td class="xl18">10093</td>
			<td>used to stimulate cells</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">EGF (epidermal growth factor, human recombinant)</td>
			<td>Peprotech</td>
			<td class="xl18">AF-100-15</td>
			<td>used to stimulate cells</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">fatty acid free BSA</td>
			<td>Sigma</td>
			<td class="xl18">A8806-1G</td>
			<td>used to make buffer for LPA and EGF</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">hematoxylin</td>
			<td>Sigma</td>
			<td class="xl18">HHS32</td>
			<td>used to stain colonies</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">eosin</td>
			<td>Electron Microscopy Sciences</td>
			<td class="xl18">26051-10</td>
			<td>used to stain colonies</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">37C, 5% CO2 incubator</td>
			<td>Sanyo</td>
			<td class="xl18">model MCO-18AIC (UV)</td>
			<td></td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">Zeiss AxioObserver with incubator chamber and motorized stage</td>
			<td>Zeiss</td>
			<td class="xl18">model Axio Observer.Z1</td>
			<td>used for time lapse imaging</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">ORCA Flash LT sCMOS camera</td>
			<td>BioVision</td>
			<td class="xl21">C11440-42U-KIT</td>
			<td>used for timelapse imaging in combination with Zeiss AxioObserver</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">Metamorph</td>
			<td>BioVision</td>
			<td class="xl18">MMACQMIC</td>
			<td>software used for time lapse imaging</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">inverted microscope</td>
			<td>Olympus</td>
			<td class="xl18">model IX70</td>
			<td>used to count cells and to check colonies in tissue culture</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td height="21" style="height:15.75pt">plastic box</td>
			<td>Lock&#38;Lock</td>
			<td class="xl18">N/A</td>
			<td>used as humid chamber (any tight closing plastic box that fits the plates can be used)</td>
		</tr>
	</tbody>
</table>

using the dot assay to analyze migration of cell sheets

Although complex organisms appear static, their tissues are under a continuous turnover. As cells age, die, and are replaced by new cells, cells move within tissues in a tightly orchestrated manner. During tumor development, this equilibrium is disturbed, and tumor cells leave the epithelium of origin to invade the local microenvironment, to travel to distant sites, and to ultimately form metastatic tumors at distant sites. The dot assay is a simple, two-dimensional unconstrained migration assay, to assess the net movement of cell sheets into a cell-free area, and to analyze parameters of cell migration using time-lapse imaging. Here, the dot assay is demonstrated using a human invasive, lung colony forming breast cancer cell line, MCF10CA1a, to analyze the cells' migratory response to epidermal growth factor (EGF), which is known to increase malignant potential of breast cancer cells and to alter the migratory phenotype of cells.

The dot assay presented here (Figure 1) was performed using invasive, lung colony forming breast cancer cells (MCF10CA1a) as a model system. The dot assay yields highly reproducible cell dots even in the hand of beginners, making it a convenient and easy to execute assay (Figure 1D). The dot assay combined with HE staining, or time-lapse imaging and subsequent particle image velocimetry (PIV) allows the&#160;stud...

Watch this Scientific Journal Video about Using the Dot Assay to Analyze Migration of Cell Sheets at JoVE.com

Using the Dot Assay to Analyze Migration of Cell Sheets

Cell migration is essential for development, tissue maintenance and repair, and tumorigenesis, and is regulated by growth factors, chemokines, and cytokines. This protocol describes the dot assay, a two-dimensional, unconstrained migration assay to assess the migratory phenotype of attached, cohesive cell sheets in response to microenvironmental cues.

Although complex organisms appear static, their tissues are under a continuous turnover. As cells age, die, and are replaced by new cells, cells move ...

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