We are grateful to Ken Iwata (OSI Pharmaceuticals, New York, USA) for reagents and Fred Miller (Barbara Ann Karmanos Cancer Intitute, Detroit, USA) for the cell lines.

1. Preparation of the methocel solution (500 mL)
<ol>
	<li>Autoclave 6 g of methylcellulose in a 500 ml bottle containing a magnetic stirrer.</li>
	<li>Dissolve the methylcellulose in 250 ml of preheated DMEM/F12 without serum (60&deg;C) for 20 min.</li>
	<li>Add 250 ml of DMEM/F12 (RT) containing 10% horse serum. Mix overnight (4&deg;C).</li>
	<li>Clear the solution by centrifugation (5000g, 2h, 4&deg;C).</li>
	<li>Take the clear highly viscous solution to a new tube (about 90-95% of the stock solution).</li>
	<li>Store at 4&deg;C until use.</li>
</ol>
2. Spheroid culture
<ol>
	<li>Prepare a 20% methocel solution (10 ml methocel and 40 ml growth medium).</li>
	<li>Wash cells twice with PBS, add 0.1% trypsin and incubate cells at 37 &deg;C</li>
	<li>Resuspend cells in growth medium and count the cells.</li>
	<li>Prepare a suspension of 10 000 cells per ml in 20% methocel.</li>
	<li>Add the cell suspension to the 96 well round bottom suspension plates (100 &mu;l per well).</li>
	<li>Next day, check the spheroid formation in the suspension plates. Spheroids will be ready for use after 1-3 days.</li>
</ol>
3. Preparation of collagen
<ol>
	<li>Prepare on ice a solution of 8 ml collagen, 1 ml 10x PBS, 1 ml 0.1 N NaOH and 3 drops 0.1 N HCl. Check if pH is 7.4 by spotting some of the solution on pH indicator strips. Adjust pH if out of range.</li>
	<li>Add 50 &mu;l of neutralized collagen solution in the wells of a 96 well plate</li>
	<li>Incubate at 37&deg;C until the collagen is solidified (90 min).</li>
	<li>Prepare methocel-collagen-ligand solutions on ice: for each ligand pipette 1 part of of collagen solution. Add 20 ng per ml of collagen TGF-&beta;. After dilution with methocel and diffusion over the different layers, the final concentration of TGF-&beta; will be 5 ng/ml Mix by vortexing. Add 1 part of methocel- solution. Mix by vortexing.</li>
</ol>
4. Spheroid embedding
<ol>
	<li>Place a 200 &mu;l tip which has approximately 5 mm of the tip cut off, on a 200 &mu;l pipette. Suck up one spheroid with the pipette and carefully dispense the medium into an empty plate. Watch if the spheroid stays inside the tip. The spheroid is visible as a white dot. Without releasing the plunger, suck up 100 &mu;l collagen-methocel mixture and dispense the spheroid in the collagen mixture into a collagen-coated 96 well. Do this for 12 spheroids for each condition.</li>
	<li>Let collagen solidify at least 30 minutes at 37&deg;C</li>
	<li>Remove air bubbles with a 200 &mu;l tip.</li>
	<li>Add 50 &mu;l of medium with 1.6 % serum and inhibitors dissolved in DMSO. For SB-431542 add 4 &mu;l of stock solution (10 mM) to 1 ml of medium. After diffusion, the final concentration of the inhibitor will be 10 &mu;M. TGF-&beta; and inhibitors will stay the course of the experiment. Take pictures of the spheroids under the microscope using 40X magnification.</li>
	<li>After 48h of stimulation with TGF-&beta; and/or inhibitors, take pictures of the spheroids under the microscope using 40X magnification.</li>
	<li>Measure the area of the invading spheroids after 2 days and subtract the starting area. Measuring the area of a spheroid: Open the picture from the spheroid in Adobe Photoshop Extended (figure 2A) and select the Quick Selection tool (figure 2B). The mouse pointer changes into a circle with a 'plus' (+) sign (figure 2C). While dragging the cursor over the spheroid, Photoshop will recognize the borders of the spheroid. If an area outside the spheroid is selected, this region can be excluded from the selection by pressing the Alt key or by using the negative selection tool which is indicated by a (-) sign in the toolbar. The cursor changes into a circle with a 'minus' (-) sign and by dragging the cursor over the wrongly selected area, this area is removed from the selection (figure 2D). If necessary, multiple regions can be selected by pressing the Shift button. To work more accurately, the size of the mouse pointer can be adjusted by changing the brush diameter in the toolbar (figure 2E). When the whole spheroid is selected, the area of the selection is calculated via ANALYSIS-MEASURE in the menu bar or by pressing Ctrl + Shift + M (figure 2F). The measurement recording window will appear showing the file name and the area of the selection in pixels, as well as other data (figure 2G). If multiple selections are measured, the first line shows the sum of all the areas. The measurements of the individual selections are presented in the lines below. The data of all the measurements can be exported into a text file and opened in Excel.</li>
</ol>
5. Representative results:
An example of the spheroid assay with MCF10A1 (M1) normal breast epithelial cells, H-RAS transformed MCF10AneoT (M2) cells and M2-derived MCF10CA1a (M4) is given in Figure 3. M1 cells showed only weak invasion without stimulation, but invaded significantly better upon stimulation by TGF-&beta;. In contrast, the RAS-transformed M1-derivative M2 invaded already efficiently without addition of stimuli, and this was further increased 4-5 fold upon TGF-&beta; treatment. M4 cells showed the strongest invasion, both with and without TGF-&beta; addition.
Next, we examined whether we could interfere with TGF-&beta;-induced invasion in this spheroid model using chemical inhibitors. For this purpose we used SB-431542, an ATP analogue and selective inhibitor of the kinase activity of T&beta;RI, as well as activin type IB receptor (ActRIB) and activin receptor-like kinase (ALK)712. As expected, SB-431542 potently inhibited TGF-&beta;-induced invasion of M1, M2 and M4 cells (Fig 4), indicating that TGF-&beta;-induced invasion is T&beta;RI-kinase dependent. In addition, the basal invasion of the spheroids was also strongly inhibited, suggesting that basal invasion is also dependent on TGF-&beta;.
<img alt="Figure 1" src="/files/ftp_upload/3337/3337fig1.jpg" /> 
Figure 1. Flow chart of the 3D spheroid assay. First, cells are plated under non-adherent conditions in u-shaped suspensions plates. Cells aggregrate into multcellular spheroids and can be embedded into a collagen matrix. Into this collagen matrix, they are able to invade.
<img alt="Figure 2" src="/files/ftp_upload/3337/3337fig2.jpg" /> 
Figure 2. Quantification of the area of the spheroids using Adobe Photoshop Extended. (A) The picture of the spheroid is opened in Adobe Photoshop Extendend (B) Selection of the Quick Selection tool (C) Dragging the cursor over the spheroid to select the area of the spheroid (D) Removal of a wongly included area using the negative Quick Selection tool (E) Adjustment of the brush size of the Quick Selection tool to more accurately select the area (F) Selection of the measurement command to record (G) Example of a measurement record.
<img alt="Figure 3" src="/files/ftp_upload/3337/3337fig3.jpg" /> 
Figure 3. TGF-&beta;-induced invasion of spheroids of spontaneously immortalised MCF10A1 (M1) (A), RAS-transformed MCF10AneoT (M2 (B) and its metastatic derivative MCF10CA1a (M4) (C). M1, M2 and M4 spheroids embedded into collagen were treated with 5ng/ml of TGF-&beta; for 48h as indicated. A-C Representative pictures taken at the day of embedding and two days later. D Relative invasion was quantified as area difference on day 2 minus day 0. The results are expressed as mean &plusmn; s.d. Adapted from13.
<img alt="Figure 4a" src="/files/ftp_upload/3337/3337fig4a.jpg" /> 
<img alt="Figure 4b" src="/files/ftp_upload/3337/3337fig4b.jpg" /> 
Figure 4. Basal and TGF-&beta;-induced spheroid invasion is inhibited by SB-431542. M1, M2 and M4 spheroids were embedded into collagen and treated with 5ng/ml TGF-&beta; and/or 10 &mu;M SB-431542 as indicated. Representative pictures taken after 2 days (A). Relative invasion was quantified as area difference on day 2 minus day 0 (B). The results are expressed as mean &plusmn; s.d. Adapted from13.

<ol>
	<li>Akhurst, R. J., Derynck, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TGF-&#946;+signaling+in+cancer--a+double-edged+sword.">TGF-&#946; signaling in cancer--a double-edged sword.</a> Trends. Cell. Biol. 11, S44-S51 (2001).</li><li>Massagu&#233;, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TGF-&#946;+in+Cancer.">TGF-&#946; in Cancer.</a> Cell. 134, 215-215 (2008).</li><li>Ghellal, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prognostic+significance+of+TGF-&#946;1+and+TGF-&#946;+in+human+breast+carcinoma.">Prognostic significance of TGF-&#946;1 and TGF-&#946; in human breast carcinoma.</a> Anticancer. Res. 20, 4413-4413 (2000).</li><li>Sheen-Chen, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum+levels+of+transforming+growth+factor-&#946;1+in+patients+with+breast+cancer.">Serum levels of transforming growth factor-&#946;1 in patients with breast cancer.</a> Arch. Surg. 136, 937-937 (2001).</li><li>ten Dijke, P., Hill, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+insights+into+TGF-&#946;-Smad+signaling.">New insights into TGF-&#946;-Smad signaling.</a> Trends Biochem. Sci. 29, 265-265 (2004).</li><li>Moustakas, A., Heldin, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-Smad+TGF-&#946;+signals.">Non-Smad TGF-&#946; signals.</a> J. Cell Sci. 118, 3573-3573 (2005).</li><li>Soule, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+characterization+of+a+spontaneously+immortalized+human+breast+epithelial+cell+line,+MCF-10.">Isolation and characterization of a spontaneously immortalized human breast epithelial cell line, MCF-10.</a> Cancer Res. 50, 6075-6075 (1990).</li><li>Strickland, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progression+of+premalignant+MCF10AT+generates+heterogeneous+malignant+variants+with+characteristic+histologic+types+and+immunohistochemical+markers.">Progression of premalignant MCF10AT generates heterogeneous malignant variants with characteristic histologic types and immunohistochemical markers.</a> Breast Cancer Res. Treat. 64, 235-235 (2000).</li><li>Santner, S. J. <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 Res. Treat. 65, 101-101 (2001).</li><li>Smalley, K. S., Lioni, M., Herlyn, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Life+isn't+flat:+taking+cancer+biology+to+the+next+dimension.">Life isn't flat: taking cancer biology to the next dimension.</a> In Vitro Cell Dev. Biol. Anim. 42, 242-242 (2006).</li><li>Kobayashi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acquired+multicellular-mediated+resistance+to+alkylating+agents+in+cancer.">Acquired multicellular-mediated resistance to alkylating agents in cancer.</a> Proc. Natl. Acad. Sci. U. S. A. 90, 3294-3294 (1993).</li><li>Inman, 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=SB-431542+is+a+potent+and+specific+inhibitor+of+transforming+growth+factor-b+superfamily+type+I+activin+receptor-like+kinase+(ALK)+receptors+ALK4,+ALK5,+and+ALK7.">SB-431542 is a potent and specific inhibitor of transforming growth factor-b superfamily type I activin receptor-like kinase (ALK) receptors ALK4, ALK5, and ALK7.</a> Mol. Pharmacol. 62, 65-65 (2002).</li><li>Wiercinska, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+TGF-&#946;/Smad+pathway+induces+breast+cancer+cell+invasion+through+the+up-regulation+of+matrix+metalloproteinase+2+and+9+in+a+spheroid+invasion+model+system.">The TGF-&#946;/Smad pathway induces breast cancer cell invasion through the up-regulation of matrix metalloproteinase 2 and 9 in a spheroid invasion model system.</a> Breast Cancer Res. Treat. 128, 657-657 (2011).</li><li>Tang, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TGF-&#946;+switches+from+tumor+suppressor+to+prometastatic+factor+in+a+model+of+breast+cancer+progression.">TGF-&#946; switches from tumor suppressor to prometastatic factor in a model of breast cancer progression.</a> J. Clin. Invest. 112, 1116-1116 (2003).</li><li>Provenzano, P. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collagen+density+promotes+mammary+tumor+initiation+and+progression.">Collagen density promotes mammary tumor initiation and progression.</a> BMC. Med. 6, 11-11 (2008).</li><li>Ramaswamy, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+molecular+signature+of+metastasis+in+primary+solid+tumors.">A molecular signature of metastasis in primary solid tumors.</a> Nat. Genet. 33, 49-49 (2003).</li><li>Debnath, J., Brugge, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modelling+glandular+epithelial+cancers+in+three-dimensional+cultures.">Modelling glandular epithelial cancers in three-dimensional cultures.</a> Nat. Rev. Cancer. 5, 675-675 (2005).</li><li>Pampaloni, F., Reynaud, E. G., Stelzer, E. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+third+dimension+bridges+the+gap+between+cell+culture+and+live+tissue.">The third dimension bridges the gap between cell culture and live tissue.</a> Nat. Rev. Mol. Cell. Biol. 8, 839-839 (2007).</li><li>Lee, G. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+culture+models+of+normal+and+malignant+breast+epithelial+cells.">Three-dimensional culture models of normal and malignant breast epithelial cells.</a> Nat. Methods. 4, 359-359 (2007).</li><li>Petersen, O. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interaction+with+basement+membrane+serves+to+rapidly+distinguish+growth+and+differentiation+pattern+of+normal+and+malignant+human+breast+epithelial+cells.">Interaction with basement membrane serves to rapidly distinguish growth and differentiation pattern of normal and malignant human breast epithelial cells.</a> Proc. Natl. Acad. Sci. U. S. A. 89, 9064-9064 (1992).</li><li>Debnath, J., Muthuswamy, S. K., Brugge, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphogenesis+and+oncogenesis+of+MCF10A+mammary+epithelial+acini+grown+in+three-dimensional+basement+membrane+cultures.">Morphogenesis and oncogenesis of MCF10A mammary epithelial acini grown in three-dimensional basement membrane cultures.</a> 30, 256-256 (2011).</li><li>Li, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=p21-Activated+kinase+1+coordinates+aberrant+cell+survival+and+pericellular+proteolysis+in+a+three-dimensional+culture+model+for+premalignant+progression+of+human+breast+cancer.">p21-Activated kinase 1 coordinates aberrant cell survival and pericellular proteolysis in a three-dimensional culture model for premalignant progression of human breast cancer.</a> 10, 314-314 (2011).</li><li>Li, Q., Chow, A. B., Mattingly, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+overlay+culture+models+of+human+breast+cancer+reveal+a+critical+sensitivity+to+mitogen-activated+protein+kinase+kinase+inhibitors.">Three-dimensional overlay culture models of human breast cancer reveal a critical sensitivity to mitogen-activated protein kinase kinase inhibitors.</a> J. Pharmacol. Exp. Ther. 332, 821-821 (2010).</li></ol>

No conflicts of interest.

We established a spheroid model in which MCF10A1 cells and its malignant derivatives invade into a collagen matrix in a TGF-&beta;&#45;dependent manner. First, spheroids are formed in 96-wells round bottom suspension plates in the presence of methylcellulose. Of course, also U-shaped poly&#45;HEMA coated plates can be used for this purpose. Methylcellulose is absolutely required in this step, since cells will die in the absence of methylcellulose. TGF&#45;&beta; is added directly to the collagen-methocel mixture since we...

<table border="1">
	<tbody>
 <tr>
	<td>Name of the reagent</td>
	<td>Company</td>
	<td>Catalogue number</td>
	<td>Comments (optional)</td>
 </tr>
 <tr>
	<td>Methyl cellulose</td>
	<td>Sigma-Aldrich</td>
	<td>M0512</td>
	<td>&nbsp;</td>
 </tr>
 <tr>
	<td>PureCol</td>
	<td>Advanced Biomatrix</td>
	<td>5005-B</td>
	<td>&nbsp;</td>
 </tr>
 <tr>
	<td>pH indicator strips</td>
	<td>Merck</td>
	<td>9533</td>
	<td>&nbsp;</td>
 </tr>
 <tr>
	<td>96-well suspension plates</td>
	<td>Greiner Bio-one</td>
	<td>650 185</td>
	<td>&nbsp;</td>
 </tr>
 <tr>
	<td>96-well adhesion TC plates</td>
	<td>Greiner Bio-one</td>
	<td>655 180</td>
	<td>&nbsp;</td>
 </tr>
 </tbody>
</table>

spheroid assay to measure tgf-&#946;-induced invasion

TGF-&beta; has opposing roles in breast cancer progression by acting as a tumor suppressor in the initial phase, but stimulating invasion and metastasis at later stage1,2. Moreover, TGF-&beta; is frequently overexpressed in breast cancer and its expression correlates with poor prognosis and metastasis 3,4. The mechanisms by which TGF-&beta; induces invasion are not well understood.
TGF-&beta; elicits its cellular responses via TGF-&beta; type II (T&beta;RII) and type I (T&beta;RI) receptors. Upon TGF-&beta;-induced heteromeric complex formation, T&beta;RII phosphorylates the T&beta;RI. The activated T&beta;RI initiates its intracellular canonical signaling pathway by phosphorylating receptor Smads (R-Smads), i.e. Smad2 and Smad3. These activated R-Smads form heteromeric complexes with Smad4, which accumulate in the nucleus and regulate the transcription of target genes5. In addition to the previously described Smad pathway, receptor activation results in activation of several other non-Smad signaling pathways, for example Mitogen Activated Protein Kinase (MAPK) pathways6.
To study the role of TGF-&beta; in different stages of breast cancer, we made use of the MCF10A cell system. This system consists of spontaneously immortalized MCF10A1 (M1) breast epithelial cells7, the H-RAS transformed M1-derivative MCF10AneoT (M2), which produces premalignant lesions in mice8, and the M2-derivative MCF10CA1a (M4), which was established from M2 xenografts and forms high grade carcinomas with the ability to metastasize to the lung9. This MCF10A series offers the possibility to study the responses of cells with different grades of malignancy that are not biased by a different genetic background.
For the analysis of TGF-&beta;-induced invasion, we generated homotypic MCF10A spheroid cell cultures embedded in a 3D collagen matrix in vitro (Fig 1). Such models closely resemble human tumors in vivo by establishing a gradient of oxygen and nutrients, resulting in active and invasive cells on the outside and quiescent or even necrotic cells in the inside of the spheroid10. Spheroid based assays have also been shown to better recapitulate drug resistance than monolayer cultures11. This MCF10 3D model system allowed us to investigate the impact of TGF-&beta; signaling on the invasive properties of breast cells in different stages of malignancy.

Watch this Scientific Journal Video about Spheroid Assay to Measure TGF-Î²-induced Invasion at JoVE.com

Spheroid Assay to Measure TGF-&amp;#946;-induced Invasion

An assay to quantitatively measure Transforming Growth Factor (TGF)-&#x03B2;-induced invasion in 3-dimensional collagen gels is described. This assay takes advantage of the MCF10A series of cell lines, which represent different stages of breast cancer development. This method can be adopted to be used with other cell lines and might be used to investigate other potential activators or inhibitors of invasion.

Spheroid Assay to Measure TGF-&#946;-induced Invasion

TGF-&beta; has opposing roles in breast cancer progression by acting as a tumor suppressor in the initial phase, but stimulating invasion and metastasis ...

spheroid-assay-to-measure-tgf-induced-invasion

Research

JoVE Journal

Medicine

21.8K vistas.  Leiden University Medical Centre. Un ensayo para medir cuantitativamente el factor transformador del crecimiento (TGF)-β-inducida por invasión en geles de colágeno en 3 dimensiones se describe. Este ensayo se aprovecha de la serie MCF10A de líneas celulares, que representan diferentes etapas de desarrollo de cáncer de mama. Este método puede ser aprobada para su uso con otras líneas celulares y podrían ser utilizados para investigar otras posibles activadores o inhibidores de la invasión.

Video: Spheroid Assay to Measure TGF-&#946;-induced Invasion

A Real-time Electrical Impedance Based Technique to Measure Invasion of Endothelial Cell Monolayer by Cancer Cells

Metastatic dissemination of malignant cells requires degradation of basement membrane, attachment of tumor cells to vascular endothelium, retraction of endothelial junctions and finally invasion and migration of tumor cells through the endothelial layer to enter the bloodstream as a means of transport to distant sites in the host1-3. Once in the circulatory system, cancer cells adhere to capillary walls and extravasate to the surrounding tissue to form metastatic tumors4,5. The various components of tumor cell-endothelial cell interaction can be replicated in vitro by challenging a monolayer of human umbilical vein endothelial cells (HUVEC) with cancer cells. Studies performed with electron and phase-contrast microscopy suggest that the in vitro sequence of events fairly represent the in vivo metastatic process6. Here, we describe an electrical-impedance based technique that monitors and quantifies in real-time the invasion of endothelial cells by malignant tumor cells.
Giaever and Keese first described a technique for measuring fluctuations in impedance when a population of cells grow on the surface of electrodes7,8. The xCELLigence instrument, manufactured by Roche, utilizes a similar technique to measure changes in electrical impedance as cells attach and spread in a culture dish covered with a gold microelectrode array that covers approximately 80% of the area on the bottom of a well. As cells attach and spread on the electrode surface, it leads to an increase in electrical impedance9-12. The impedance is displayed as a dimensionless parameter termed cell-index, which is directly proportional to the total area of tissue-culture well that is covered by cells. Hence, the cell-index can be used to monitor cell adhesion, spreading, morphology and cell density.
The invasion assay described in this article is based on changes in electrical impedance at the electrode/cell interphase, as a population of malignant cells invade through a HUVEC monolayer (Figure 1). The disruption of endothelial junctions, retraction of endothelial monolayer and replacement by tumor cells lead to large changes in impedance. These changes directly correlate with the invasive capacity of tumor cells, i.e., invasion by highly aggressive cells lead to large changes in cell impedance and vice versa. This technique provides a two-fold advantage over existing methods of measuring invasion, such as boyden chamber and matrigel assays: 1) the endothelial cell-tumor cell interaction more closely mimics the in vivo process, and 2) the data is obtained in real-time and is more easily quantifiable, as opposed to end-point analysis for other methods.

This article describes an in vitro technique for monitoring cancer cells invading through a monolayer of endothelial cells. The data is acquired in real-time as a function of changes in impedance on the surface of electrodes at the well bottom.

Metastatic dissemination of malignant cells requires degradation of basement membrane, attachment of tumor cells to vascular endothelium, retraction of ...

Method to Measure Tone of Axial and Proximal Muscle

The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs1, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention.

We have developed a device (Twister) to study the regulation of tonic muscle activity during active postural maintenance. Twister measures torsional resistance and muscular responses in standing subjects during twisting of the body axis. The device can be flexibly configured to study various aspects of tonic control across the neck, trunk, and/or hips.

The control of tonic muscular activity remains poorly understood.  While abnormal tone is commonly assessed clinically by measuring the passive resistance ...

Accuracy in Dental Medicine, A New Way to Measure Trueness and Precision

Reference scanners are used in dental medicine to verify a lot of procedures. The main interest is to verify impression methods as they serve as a base for dental restorations. The current limitation of many reference scanners is the lack of accuracy scanning large objects like full dental arches, or the limited possibility to assess detailed tooth surfaces. A new reference scanner, based on focus variation scanning technique, was evaluated with regards to highest local and general accuracy. A specific scanning protocol was tested to scan original tooth surface from dental impressions. Also, different model materials were verified. The results showed a high scanning accuracy of the reference scanner with a mean deviation of 5.3 &#177; 1.1 &#181;m for trueness and 1.6 &#177; 0.6 &#181;m for precision in case of full arch scans. Current dental impression methods showed much higher deviations (trueness: 20.4 &#177; 2.2 &#181;m, precision: 12.5 &#177; 2.5 &#181;m) than the internal scanning accuracy of the reference scanner. Smaller objects like single tooth surface can be scanned with an even higher accuracy, enabling the system to assess erosive and abrasive tooth surface loss. The reference scanner can be used to measure differences for a lot of dental research fields. The different magnification levels combined with a high local and general accuracy can be used to assess changes of single teeth or restorations up to full arch changes.

Accuracy is a major demand in dental medicine. To verify accuracy, reference scanners are needed. This article presents a new reference scanner with an adjusted scanning method to acquire a broad variety of dental morphologies with high trueness and precision.

Reference scanners are used in dental medicine to verify a lot of procedures. The main interest is to verify impression methods as they serve as a base ...

A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones, Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion

Blood serum serves as a chemoattractant towards which cancer cells migrate and invade, facilitating their intravasation into microvessels. However, the actual molecules towards which the cells migrate remain elusive. This modified invasion assay has been developed to identify targets which drive cell migration and invasion. This technique compares the invasion index under three conditions to determine whether a specific hormone, growth factor, or cytokine plays a role in mediating the invasive potential of a cancer cell. These conditions include i) normal fetal bovine serum (FBS), ii) charcoal-stripped FBS (CS-FBS), which removes hormones, growth factors, and cytokines and iii) CS-FBS + molecule (denoted &#8220;X&#8221;). A significant change in cell invasion with CS-FBS as compared to FBS, indicates the involvement of hormones, cytokines or growth factors in mediating the change. Individual molecules can then be added back to CS-FBS to assay their ability to reverse or rescue the invasion phenotype. Furthermore, two or more factors can be combined to evaluate the additive or synergistic effects of multiple molecules in driving or inhibiting invasion. Overall, this method enables the investigator to determine whether hormones, cytokines, and/or growth factors play a role in cell invasion by serving as chemoattractants or inhibitors of invasion for a particular type of cancer cell or a specific mutant. By identifying specific chemoattractants and inhibitors, this modified invasion assay may help to elucidate signaling pathways that direct cancer cell invasion.

A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones, Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion

This video article describes a modified in vitro method to examine the role of hormones, cytokines and/or growth factors in driving cancer cell invasion.

Blood serum serves as a chemoattractant towards which cancer cells migrate and invade, facilitating their intravasation into microvessels. However, the ...

Assessment of Ovarian Cancer Spheroid Attachment and Invasion of Mesothelial Cells in Real Time

Ovarian cancers metastasize by shedding into the peritoneal fluid and dispersing to distal sites within the peritoneum. Monolayer cultures do not accurately model the behaviors of cancer cells within a nonadherent environment, as cancer cells inherently aggregate into multicellular structures which contribute to the metastatic process by attaching to and invading the peritoneal lining to form secondary tumors. To model this important stage of ovarian cancer metastasis, multicellular aggregates, or spheroids, can be generated from established ovarian cancer cell lines maintained under nonadherent conditions. To mimic the peritoneal microenvironment encountered by tumor cells in vivo, a spheroid-mesothelial co-culture model was established in which preformed spheroids are plated on top of a human mesothelial cell monolayer, formed over an extracellular matrix barrier. Methods were then developed using a real-time cell analyzer to conduct quantitative real time measurements of the invasive capacity of different ovarian cancer cell lines grown as spheroids. This approach allows for the continuous measurement of invasion over long periods of time, which has several advantages over traditional endpoint assays and more laborious real time microscopy image analyses. In short, this method enables a rapid, determination of factors which regulate the interactions between ovarian cancer spheroid cells invading through mesothelial and matrix barriers over time.

Ovarian cancer cell invasion into the mesothelial lining of the peritoneum is a dynamic process over time. Utilizing a real time analyzer, the invasive capacity of ovarian cancer cells in a spheroid-mesothelial cell co-culture model can be quantified over prolonged time periods, providing insights into factors regulating the metastatic process.

Ovarian cancers metastasize by shedding into the peritoneal fluid and dispersing to distal sites within the peritoneum. Monolayer cultures do not ...

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. Despite the discovery of key regulators of uterine contractility, this process is still not fully understood. Transgenic mice provide an ideal model in which to study parturition. Previously, the only method to study uterine contractility in the mouse was ex vivo isometric tension recordings, which are suboptimal for several reasons. The uterus must be removed from its physiological environment, a limited time course of investigation is possible, and the mice must be sacrificed. The recent development of radiometric telemetry has allowed for longitudinal, real-time measurements of in vivo intrauterine pressure in mice. Here, the implantation of an intrauterine telemeter to measure pressure changes in the mouse uterus from mid-pregnancy until delivery is described. By comparing differences in pressures between wild type and transgenic mice, the physiological impact of a gene of interest can be elucidated. This technique should expedite the development of therapeutics used to treat myometrial disorders during pregnancy, including preterm labor.

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

This manuscript provides a protocol for implanting telemeters in the mouse for the purpose of measuring intrauterine pressures during pregnancy.

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. ...

Establishment of a Human Multiple Myeloma Xenograft Model in the Chicken to Study Tumor Growth, Invasion and Angiogenesis

Multiple myeloma (MM), a malignant plasma cell disease, remains incurable and novel drugs are required to improve the prognosis of patients. Due to the lack of the bone microenvironment and auto/paracrine growth factors human MM cells are difficult to cultivate. Therefore, there is an urgent need to establish proper in vitro and in vivo culture systems to study the action of novel therapeutics on human MM cells. Here we present a model to grow human multiple myeloma cells in a complex 3D environment in vitro and in vivo. MM cell lines OPM-2 and RPMI-8226 were transfected to express the transgene GFP and were cultivated in the presence of human mesenchymal cells and collagen type-I matrix as three-dimensional spheroids. In addition, spheroids were grafted on the chorioallantoic membrane (CAM) of chicken embryos and tumor growth was monitored by stereo fluorescence microscopy. Both models allow the study of novel therapeutic drugs in a complex 3D environment and the quantification of the tumor cell mass after homogenization of grafts in a transgene-specific GFP-ELISA. Moreover, angiogenic responses of the host and invasion of tumor cells into the subjacent host tissue can be monitored daily by a stereo microscope and analyzed by immunohistochemical staining against human tumor cells (Ki-67, CD138, Vimentin) or host mural cells covering blood vessels (desmin/ASMA).
In conclusion, the onplant system allows studying MM cell growth and angiogenesis in a complex 3D environment and enables screening for novel therapeutic compounds targeting survival and proliferation of MM cells.

Human multiple myeloma (MM) cells require the supportive microenvironment of mesenchymal cells and extracellular matrix components for survival and proliferation. We established an in vivo chicken embryo model with engrafted human myeloma and mesenchymal cells to study effects of cancer drugs on tumor growth, invasion and angiogenesis.

Multiple myeloma (MM), a malignant plasma cell disease, remains incurable and novel drugs are required to improve the prognosis of patients. Due to the ...

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 ...

Chick Heart Invasion Assay for Testing the Invasiveness of Cancer Cells and the Activity of Potentially Anti-invasive Compounds

The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish between invasive and non-invasive cells, and enables study of the effects of test compounds on tumor invasion. Cancer cells - either as aggregates or single cells - are confronted with fragments of embryonic chick heart. After organ culture in suspension for a few days or weeks the confronting cultures are fixed and embedded in paraffin for histological analysis. The three-dimensional interaction between the cancer cells and the normal tissue is then reconstructed from serial sections stained with hematoxylin-eosin or after immunohistochemical staining for epitopes in the heart tissue or the confronting cancer cells. The assay is consistent with the recent concept that cancer invasion is the result of molecular interactions between the cancer cells and their neighbouring stromal host elements (myofibroblasts, endothelial cells, extracellular matrix components, etc.). Here, this stromal environment is offered to the cancer cells as a living tissue fragment. Supporting aspects to the relevance of the assay are multiple. Invasion in the assay is in accordance with the criteria of cancer invasion: progressive occupation and replacement in time and space of the host tissue, and invasiveness and non-invasiveness in vivo of the confronting cells generally correlates with the outcome of the assay. Furthermore, the invasion pattern of cells in vivo, as defined by pathologists, is reflected in the histological images in the assay. Quantitative structure-activity relation (QSAR) analysis of the results obtained with numerous potentially anti-invasive organic congener compounds allowed the study of structure-activity relations for flavonoids and chalcones, and known anti-metastatic drugs used in the clinic (e.g., microtubule inhibitors) inhibit invasion in the assay as well. However, the assay does not take into account immunological contributions to cancer invasion.

Here, we present a protocol to study the invasion of tumor cells into living normal tissue fragments in three dimensions. This organ culture technique is mainly applied to test potentially anti-invasive drugs in vitro.

The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish ...

A Cancer Cell Spheroid Assay to Assess Invasion in a 3D Setting

The invasive nature of cancer cell lines is thought to correlate with their metastatic potential. Most traditional assays, however, do not examine these invasive features in a three-dimensional environment and the resulting data suffer from reduced biological applicability. Here an approach is presented to visualize the invasive ability of cell lines in a physiologically relevant setting. The cancer cell spheroid invasion assay first utilizes gravity to generate spheroids within drops of media that hang from the lid of a cell culture dish. Next, these spheroids are embedded in a 3D matrix consisting of a mixture of basement membrane materials and type I collagen. Cancer cell egression from the spheroids into the surrounding matrix is then monitored over time. The method described here can be modified to examine invasion after coculture of different cell types, inclusion of drugs/inhibitors, or alterations in extracellular matrix (ECM) constituents.

This method evaluates cancer cell invasion from spheroids into a surrounding 3D matrix. Spheroids are generated via the hanging drop culture method and then embedded in a matrix comprised of basement membrane materials and type I collagen. Invasion out of the spheroids is subsequently monitored.

The invasive nature of cancer cell lines is thought to correlate with their metastatic potential.  Most traditional assays, however, do not examine these ...