The authors acknowledge funding sources from D&#8217;Youville College School of Pharmacy, Buffalo, NY.

1. Prepare the Different Media and Additional Components
<ol>
	<li>Prior to experiment, prepare media consisting of DMEM or other specified media with the addition of either normal FBS, charcoal stripped FBS, or charcoal stripped FBS plus the component to be tested. Note that multiple components can be tested in each experiment.</li>
	<li>Weigh out and dilute the hormones, growth factors, or cytokines appropriately to be dissolved in the charcoal stripped serum at the physiological concentration.</li>
</ol>
2. Prepare the Collagen Matrix on Ice
<ol>
	<li>Prepare 2 ml collagen I matrix at 2.2 mg/ml by adding the following sterile filtered components on ice: 200 &#956;l 10x PBS (pH 7.4), 5.4 &#956;l 1 N NaOH, 600 &#956;l of double distilled H2O, and 1.2 ml collagen I (at 3.63 mg/ml).</li>
	<li>Keep collagen I solution on ice until ready to plate.</li>
</ol>
3. Prepare Migration/Invasion Plates for Assay
<ol>
	<li>For each cell line to be tested, use one 24-well chamber plate in which 12-wells contain inserts. Use the additional 12 wells that do not contain inserts for adding the chemoattractant media and transferring the inserts for the experimental set up. 
	NOTE: A collagen matrix on plates with a polyethylene teraphthalate (PET) membrane and 8 &#956;m pore size is optimal for the cell lines use here. However, a matrigel matrix in precoated plates can also be substituted with the pore size decreased according to the cell line being investigated.</li>
	<li>Clearly label the plate, using 3 wells per condition being analyzed (FBS migration, CS-FBS migration, FBS invasion, and CS-FBS invasion as well as FBS-migration for a control, noninvasive cell line). Assay migration by movement through pores in a PET membrane, and assay invasion by movement through a collagen or matrigel matrix and then through pores in the membrane. Use different color markers for each cell condition to aid in the plating process.</li>
</ol>
4. Dispense the Invasion Matrix
<ol>
	<li>Carefully pipette 75 &#956;l of the collagen matrix solution into the inserts to be used for invasion assays. Use caution to avoid bubbles. Disperse bubbles by applying an inverted pipette tip to the surface.</li>
	<li>Transfer the plate with the collagen-coated inserts to a 37 &#176;C and 5% CO2 incubator for 30 min to enable the gel to solidify.</li>
</ol>
5. Plate the Cells onto the Membrane or Invasion Matrix
<ol>
	<li>Meanwhile, trypsinize cells and add media with 10% FBS. Spin cells at 200 x g for 5 min on a table top centrifuge and rinse 3x in serum free media.</li>
	<li>Resuspend in serum free media. Count cells with a hemocytometer or automated slide counter. Add serum free media to a final concentration of 5 x 104 cells/ml.</li>
	<li>When the collagen matrix has solidified (after 30 min), add 700 &#956;l of media with either 2% defined FBS or charcoal-stripped FBS to each well. Of the 12 inserts per plate:
	<ul>
		<li>3 inserts have collagen and wells with media + 2% FBS</li>
		<li>3 inserts have collagen and wells with media + 2% CS-FBS</li>
		<li>3 inserts have no collagen and wells with media + 2% FBS</li>
		<li>3 inserts have no collagen and wells with media + 2% CS-FBS</li>
	</ul>
	<ol>
		<li>Use additional plates depending on the number of factors being tested and with a no collagen control corresponding to each condition.</li>
	</ol>
	</li>
	<li>Add cell suspension to the inserts at 5 x 104 cells/ml, plating 500 &#956;l cells per insert in all migration and invasion inserts.</li>
	<li>Incubate the cells for 22 hr at 37 &#176;C.</li>
</ol>
6. Quantify the Number of Migrating and Invading Cells
<ol>
	<li>Set up staining of wells using methanol fixative, eosin, and hemotoxylin, in separate wells.</li>
	<li>Use cotton swabs to remove cells and matrix from each well. Rrepeat with second swab application for each well.</li>
	<li>With forceps, dip each insert 5 times for 1 sec into each of the 3 solutions in succession.</li>
	<li>Allow inserts to dry O/N.</li>
	<li>Either i) remove filters with a scalpel, cutting carefully around the edges and mount on a slide with coverslip and immersion oil, or ii) allow the inserts to dry O/N inverted and use the inserts directly for microscopy.</li>
	<li>The next day, view slides or inserts under a microscope with a 20X objective and take 5 images from different regions of the filter. To improve consistency, take 4 outer fields and one center.</li>
	<li>Count cells for all conditions using the ImageJ software and apply to the formulas below.</li>
	<li>Determine the percent invasion as follows: 
	Mean # of cells invading through collagen I insert = a 
	Mean # of cells migrating through control insert = b 
	% Invasion = (a / b) * 100</li>
	<li>Determine the Invasion Index in 2% FBS as follows: 
	% invasion of cells being assayed (in 2% FBS) = c 
	% invasion of control noninvasive cells in (2% FBS) = d 
	Invasion Index (FBS) = (c / d)</li>
	<li>Determine the Invasion Index in 2% CS-FBS as follows: 
	% invasion of cells being assayed (in 2% CS-FBS) = e 
	% invasion of control noninvasive cells in (2% CS-FBS) = f 
	Invasion Index (CS-FBS) = (e / f)</li>
</ol>
7. Repeat Experimental Protocol Comparing Charcoal-stripped FBS to Charcoal-stripped FBS + Xn with Multiple Factors Combined
<ol>
	<li>Repeat the procedure multiple times as needed using different components for &#8220;X&#8221; or a combination of components.</li>
	<li>Apply the calculations to determine the contribution of each factor &#8220;X&#8221; to the migration and invasion effects.</li>
</ol>

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The authors have nothing to disclose.

Tumor metastasis is a multistep process. The cells must break through the basement membrane, intravasate into either the lymphatic system or blood microvessels, in which they are transported to distant sites. The tumor cells then extravasate and colonize into a macrometastasis12. Progression through the epithelial to mesenchymal transition (EMT), tumor invasion, and metastasis has been enhanced by steroid hormones13,14, growth factors15-18, and cytokines19-21. These molecules a...

A novel invasion assay has been developed with the goal of identifying the involvement of specific hormones, cytokines and/or growth factors as chemoattractants in cancer cell invasion. The ability of tumor cells to invade through the extracellular matrix (ECM) is a hallmark of the metastatic phenotype1-3. Invasion chambers have been extensively used as in vitro tools to study cancer cell invasion and migration and may provide knowledge as to the mechanisms of in vivo tumor invasion and metastasis. The chambers consist of cylindrical cell culture inserts nested within the wells of cell culture plates. The bottoms of the inserts are semi-permeable polycarbonate or polystyrene membranes of defined pore sizes.
In the standard invasion assay, cells are seeded onto the insert membrane with serum free media and placed into cell culture wells that are filled with serum or serum-like chemoattractants to set up a chemoattractive force. This force drives cells to move through the semi-permeable membrane (migration) or alternatively, through a coating of extracellular matrix (invasion), which can then be stained using conventional dyes to detect and quantify the number of cells. The cell number is then normalized according to the extent of migration and invasion in a noninvasive cell line. This method allows an investigator to evaluate the invasive potential of different cell types under a variety of conditions, including genetic manipulations.
Hormones, cytokines and growth factors are critical components of serum and are increasingly being shown to be associated with driving the invasive phenotype4. However, the nature, role, and specificity of these chemoattractive serum molecules in mediating invasion still remain elusive. The challenge remains to determine what specific factors in serum or serum-like chemoattractants are responsible for driving cancer cell invasion as well as what molecules may inhibit the invasion process. In this report, we describe a methodology to evaluate the potential involvement of hormones, cytokines and/or growth factors present in serum, as molecules driving the chemoattraction and invasion of cancer cells.
In this proposed modified protocol, charcoal stripping is used to remove hormones, cytokines and growth factors from 2% fetal bovine serum (FBS) to generate 2% charcoal stripped FBS (CS-FBS). Both 2% FBS and 2% CS-FBS are used as agents to set up the chemoattractive force to drive cancer cell invasion. Using 2% CS-FBS as a chemoattractive agent in comparison to normal 2% FBS affords several benefits including first, and most prominently, the ability to study the cancer invasion phenotype in the reduced/relative absence of hormones, cytokines and growth factors. It also enables the investigator to assess whether the collective removal of hormones, growth factors, and cytokines causes an increase or decrease in the invasive index. The assay is then designed to determine whether the addition of an individual component, designated as &#8220;X&#8221; can inhibit, decrease, increase, or restore the invasive index to its original value (see Figures 2 &#38; 3). Although this methodology is specific for achieving the physiological levels of the component that is removed from the serum during charcoal stripping, it should also be noted that charcoal stripping can also affect signal transduction pathways. For example, it has been reported that charcoal stripping can decrease the alkaline phosphatase activity of osteoprogenitor cells and induce adipogenesis through reduction of MAPK activators5. Charcoal stripped media are commercially available and are based on the protocol outlined that combines charcoal with dextran and incubated with fetal bovine serum O/N6.
This assay was developed in response to a result reported by Zucker et al.7 The authors demonstrated that a mutant phenotype affecting gap junction communication demonstrated an increase in the invasion index when migrating toward media with normal 2% FBS. This increase was eliminated with the substitution of charcoal-stripped serum. From this result, the authors concluded that this mutant affected migration toward a lipophilic molecule (more specifically, a hormone, growth factor, or cytokine)7. It is well known that hormones, growth factors, and cytokines mediate signaling pathways involved in tumor promotion and invasion4. Thus, it is important for scientific investigators to determine what factor(s) are driving the tumor invasion of their particular cancer cells or mutants under study. The assay is designed to address the role of individual components at their physiological concentration as determined according to the difference between the concentration of the component &#8220;X&#8221; in normal FBS and the CS-FBS. Through the development of this assay, investigators can gain more insight into the specific invasive pathway governing their system.
Hormones, growth factors, and cytokines have often been classified as tumor promoters8. Some of these factors such as EGF are used as direct sources for chemoattractants in invasion chambers9. Thus, it seems likely that these represent the major components of the serum that direct tumor invasion. This protocol proposes a simple, yet significant, modification to the conventional in vitro invasion assay which allows an investigator to assess the involvement of hormones, growth factors, and cytokines in mediating the invasive potential of cancer cells. However, the assay is designed to provide the investigator with an answer as to whether the procedure will be effective for their study at an early step in the analysis, so as not to use precious time and resources if deemed unnecessary. This method uses CS-FBS and relies on the investigators discretion as to which molecules to pursue as lead candidates that potentially mediate cancer cell invasion. The results from these analyses should prove to be useful in identifying which serum components serve as chemoattractants or inhibitors for the particular cell line or mutant being studied. In addition, this approach may help the investigator identify key signaling pathways either promoting or inhibiting cancer cell invasion; thus directing future drug design.

<table><tbody><tr><td>BioCoat Control Inserts with 8.0 &amp;micro;m PET membrane</td><td>Corning</td><td>354578</td><td>12 in each of two 24-well plates. PET = polyethylene teraphthalate</td></tr><tr><td>Collagen I, rat tail</td><td>Corning</td><td>354236</td><td>Source = rat tail tendon, purity = 90%</td></tr><tr><td>Fixative; Diff-Quick</td><td>Thermo Fisher Scientific</td><td>NC9844047</td><td>Methanol-based fixative, hematoxylin/eosin</td></tr><tr><td>Fetal bovine serum</td><td>Life Technologies</td><td>16000</td><td>Designated as FBS</td></tr><tr><td>Charcoal stripped fetal bovine serum</td><td>Life Technologies</td><td>12676</td><td>Designated as CS-FBS</td></tr><tr><td>Fetal bovine serum</td><td>Thermo Scientific Hyclone</td><td>SH30070</td><td>Designated as FBS</td></tr><tr><td>Charcoal stripped fetal bovine serum</td><td>Thermo Scientific Hyclone</td><td>SH30068</td><td>Designated as CS-FBS</td></tr></tbody></table>

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.

The invasion index is calculated for each condition according to normalization to a noninvasive cell line. For our experiments, we use the 1205Lu melanoma cell line and established variant stable cell lines as our invasive lines as well as the premalignant noninvasive variant, WM793 from which the 1205Lu cells were derived10 which serves as a logical control. We also utilize collagen I as the invasion matrix because that is the primary component of the dermis. This is in accordance with a previous study whereb...

Watch this Scientific Journal Video about A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones, Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion at JoVE.com

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.

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 ...

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Research

JoVE Journal

Medicine

10.7K Views.  Roswell Park Cancer Institute. 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.

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

Moving Upwards: A Simple and Flexible In Vitro Three-dimensional Invasion Assay Protocol

Although 3D invasion assays have been developed, the challenge remains to study cells without affecting the integrity of their microenvironment. Traditional 3D assays such as the Boyden Chamber require that cells are displaced from the original culture location and moved to a new environment. Not only does this disrupt the cellular processes that are intrinsic to the microenvironment, but it often results in a loss of cells. These problems are especially challenging when dealing with cells that are either rare, or extremely sensitive to their microenvironment. Here, we describe the development of a 3D invasion assay that avoids both concerns. In this assay, cells are plated within a small well and an ECM matrix containing a chemoattractant is laid atop the cells. This requires no cell displacement, and allows the cells to invade upwards into the matrix. In this assay, cell invasion as well as cell morphology can be assessed within the collagen gel. Using this assay, we characterize the invasive capacity of rare and sensitive cells; the hybrid cells resulting from fusion between breast cancer cells MCF7 and mesenchymal/multipotent stem/stroma cells (MSCs).

Moving Upwards: A Simple and Flexible In Vitro Three-dimensional Invasion Assay Protocol

This protocol describes an inverted vertical invasion assay that could be used to quantify the migration and invasion capabilities of cells in a three-dimensional setting while preserving the cell microenvironment. This assay is suitable for rare and/or sensitive cells.

Although 3D invasion assays have been developed, the challenge remains to study cells without affecting the integrity of their microenvironment. ...

Cancer Research

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.

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.

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

The Use of Mouse Mammary Tumor Cells in an In Vitro Invasion Assay as a Measure of Oncogenic Cell Behavior

The in vitro invasion assay uses a protein-rich matrix in a Boyden chamber to measure the ability of cultured cells to pass through the matrix and a porous membrane in a process analogous to the initial steps of cancer cell metastasis. The tested cells can be altered for the gene expression or treated with inhibitors to test for changes in the invasion potential. This experiment tests the aggressive phenotype of the mouse mammary tumor cells to discover and characterize the potential oncogenes that promote cell invasion. This technique, however, can be versatile and adapted to many different applications. The experiment itself can be done in one day and the results are acquired by light microscopy in less than a day. The results include counts of the number of invading cells for comparison and analysis. The in vitro invasion assay is a rapid, inexpensive, and clear-cut method for determining cell behavior in a culture that can be used as an initial assessment before more involved in vivo assays.

The in vitro cell invasion assay is used to measure the potential of cancer metastasis by quantifying the cellular potential for invasion and migration using cell culture inserts containing protein matrix. Cells are challenged to migrate through the protein matrix and a porous membrane, towards a chemoattractant, and then quantified by light microscopy.

The in vitro invasion assay uses a protein-rich matrix in a Boyden chamber to measure the ability of cultured cells to pass through the matrix and a ...

Genetics

Monitoring Cancer Cell Invasion and T-Cell Cytotoxicity in 3D Culture

Significant progress has been made in treating cancer with immunotherapy, although a large number of cancers remain resistant to treatment. A limited number of assays allow for direct monitoring and mechanistic insights into the interactions between tumor and immune cells, amongst which, T-cells play a significant role in executing the cytotoxic response of the adaptive immune system to cancer cells. Most assays are based on two-dimensional (2D) co-culture of cells due to the relative ease of use but with limited representation of the invasive growth phenotype, one of the hallmarks of cancer cells. Current three-dimensional (3D) co-culture systems either require special equipment or separate monitoring for invasion of co-cultured cancer cells and interacting T-cells.
Here we describe an approach to simultaneously monitor the invasive behavior in 3D of cancer cell spheroids and T-cell cytotoxicity in co-culture. Spheroid formation is driven by enhanced cell-cell interactions in scaffold-free agarose microwell casts with U-shaped bottoms. Both T-cell co-culture and cancer cell invasion into type I collagen matrix are performed within the microwells of the agarose casts without the need to transfer the cells, thus maintaining an intact 3D co-culture system throughout the assay. The collagen matrix can be separated from the agarose cast, allowing for immunofluorescence (IF) staining and for confocal imaging of cells. Also, cells can be isolated for further growth or subjected to analyses such as for gene expression or fluorescence activated cell sorting (FACS). Finally, the 3D co-culture can be analyzed by immunohistochemistry (IHC) after embedding and sectioning. Possible modifications of the assay include altered compositions of the extracellular matrix (ECM) as well as the inclusion of different stromal or immune cells with the cancer cells.

The presented approach simultaneously evaluates cancer cell invasion in 3D spheroid assays and T-cell cytotoxicity. Spheroids are generated in a scaffold-free agarose multi-microwell cast. Co-culture and embedding in type I collagen matrix are performed within the same device which allows to monitor cancer cell invasion and T-cell mediated cytotoxicity.

Significant progress has been made in treating cancer with immunotherapy, although a large number of cancers remain resistant to treatment. A limited ...

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 ...

3D Models in Cancer Biology: Invasion Dynamics in Heterospheroids

Alternative Strategy to Analyze In Vitro Cell Invasion of 3D Cultures

Spheroid culture is a 3D model that provides an improved replication of the in vivo microenvironment compared to traditional two-dimensional (2D) cultures. Invasion is a cellular outcome of utmost interest in cancer biology. In this protocol, we have devised an alternative strategy for evaluating cancer cell invasion in vitro, employing heterospheroids comprised of oral squamous cell carcinoma (OSCC), cancer-associated fibroblasts (CAF), and monocytes. These heterospheroids aim to mimic the tumor microenvironment (TME), including two relevant non-neoplastic cell types alongside the cancer cells. Each cell type was labeled with vital fluorescent markers emitting in distinct wavelengths before spheroid formation. Once formed, heterospheroids were seeded onto a layer of human leiomyoma-derived extracellular matrix in the upper compartment of a microporous membrane. Invasion was assessed in the z-axis using confocal microscopy. Digital images were obtained in the corresponding fluorescent channels at 10 &#181;m intervals, covering a depth of 90 &#181;m in the z-axis. Analysis was performed using freeware image software by calculating the integrated fluorescence intensity in each image and fluorescence channel. This approach enables a more dynamic analysis of cell invasion patterns in a multilayered context, as well as the examination of spatial co-localization of different cell types during invasion.

Invasion is a major biological phenomenon in the development and progression of cancer. This process is influenced by non-neoplastic cells and components of the tumor microenvironment. The purpose of this study is to describe an alternative method for analyzing tumor cell invasion in vitro using three-dimensional (3D) cultures.

Spheroid culture is a 3D model that provides an improved replication of the in vivo microenvironment compared to traditional two-dimensional (2D) ...

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 ...

In vitro Cell Migration and Invasion Assays

Migration is a key property of live cells and critical for normal development, immune response, and disease processes such as cancer metastasis and inflammation. Methods to examine cell migration are very useful and important for a wide range of biomedical research such as cancer biology, immunology, vascular biology, cell biology and developmental biology. Here we use tumor cell migration and invasion as an example and describe two related assays to illustrate the commonly used, easily accessible methods to measure these processes. The first method is the cell culture wound closure assay in which a scratch is generated on a confluent cell monolayer. The speed of wound closure and cell migration can be quantified by taking snapshot pictures with a regular inverted microscope at several time intervals. More detailed cell migratory behavior can be documented using the time-lapse microscopy system. The second method described in this paper is the transwell cell migration and invasion assay that measures the capacity of cell motility and invasiveness toward a chemo-attractant gradient. It is our goal to describe these methods in a highly accessible manner so that the procedures can be successfully performed in research laboratories even just with basic cell biology setup.

In vitro Cell Migration and Invasion Assays

Commonly used, highly accessible methods for examining cell migration and invasion in vitro are described. The first method is the cell wound closure assay that measures cell motility. The second method is the transwell migration and invasion assay that assesses the chemotactic and invasive capacity of cells.

Migration is a key property of live cells and critical for normal development, immune response, and disease processes such as cancer metastasis and ...

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

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