We thank Dr. Rosana De Lima Pagano and Ana Carolina Pinheiro Campos for technical assistance. This work was supported by grants from: FAPESP - S&#227;o Paulo Research Foundation (2016/07463-4) and Ludwig Institute for Cancer Research (LICR).

LNs were recovered from fresh carcasses of healthy adult Wistar rats sacrificed by cervical dislocation. We followed the NIH Guidelines for Pain and Distress in Laboratory Animals and all procedures were approved by the Ethics Committee and Animal Research of the Research and Education Institute of the S&#237;rio-Liban&#234;s hospital (CEUA P 2016-04).
NOTE: All fresh frozen tissues are considered biohazardous and should be handled using appropriate biosafety precautions.
1. Lymphadenectomy and Cryosectioning
<ol>
	<li>Place fresh carcasses of adult Wistar rats (180-220 g) lying in dorsal recumbency on a clean dissection board at room temperature. 
	NOTE: LNs must be collected up to 30 min post euthanasia.</li>
	<li>Spray the rat carcass with 70% isopropyl alcohol and use sterilized instruments for LN harvesting.</li>
	<li>Lift the abdominal skin with the aid of tweezers and open a cavity with a medial incision without damaging the underlying tissue, exposing the abdominal viscera. Pull out the intestine and the thoracic and abdominal LNs become visible (Figure 1).</li>
	<li>Carefully excise the LNs from each rat with the use of blunt tip scissors to avoid injuring the superior mesenteric artery lying behind. 
	NOTE: Depending on the location of the resected lymph node, it is necessary to clean other tissues adhered to it, such as mesenteric tissue.</li>
	<li>Harvest LNs into 15 mL conical tubes containing 5 mL of sterile phosphate buffered saline (PBS).</li>
	<li>Properly discard the rat carcasses.</li>
	<li>Remove fresh LNs from the PBS, roll and dry the node on a dry filter paper. Place it in a small Petri dish and add embedding solution for frozen tissue specimens (O.C.T.) for 2 min.</li>
	<li>Transfer and orientate the LN face down in a desired position in the base of a cryomold, with just enough O.C.T to cover it. Avoid bubbles near the tissue. The sectioning surface is the bottom of the cryomold.</li>
	<li>Immediately snap-freeze the cryomold in a Styrofoam cooler with dry ice. When there is still a small part of unfrozen O.C.T. (~20-35 s), transfer the sample to aluminum foil and place it in a cooler with dry ice while continuing to freeze other samples. At the end, store all samples at -80 &#176;C until sectioning.</li>
	<li>Section the LN with a cryostat adjusting section thickness to 5-8 &#181;m. Transfer crysections onto microscope slides. 
	NOTE: Before sectioning, remove the frozen samples from the -80 &#176;C freezer and allow them to equilibrate to the temperature in the cryostat microtome chamber at -22 &#176;C for approximately 30 min. LN-containing slides can be stored at -80 &#176;C for up to one month.</li>
</ol>
2. Cellular Labeling with Fluorescent Dyes
NOTE: Fluorescent dyes are widely used in cell biology. We prefer to use the long-chain dialkylcarbocyanines labeling (DiI(C18), excitation 549 nm, Emission 565 nm) because they are bright, stable and can be added directly to culture media, does not affecting cell viability or cell adhesive properties25,26.
<ol>
	<li>Dissociate cells growing under ideal conditions (i.e., in complete medium) and resuspend in serum-free medium at a density of 106 cells/mL.</li>
	<li>Add 1 mL of cell suspension (106 cells) to a15 mL conical tube and label with Dil(C18) (2 &#181;g/mL) for 10 min at 37 &#176;C. 
	NOTE: After 5 min, gently agitate the tubes to avoid cell sedimentation and understaining of sedimented cells. Larger densities require longer incubation times for uniform staining. An optimal incubation time for cell staining varies with cell line. It can be better quantified using the conventional FL2 flow cytometry detection channel (Figure 2A).</li>
	<li>Centrifuge the labeled suspension tubes at 300 x g for 4 min.</li>
	<li>Remove the supernatant and wash twice in 10 mL of serum-free medium. Recover the cells as red pellets. Resuspend the cells at 106 cells/mL in serum-free medium with 0.1% bovine serum albumin (BSA).</li>
</ol>
3. Precoating Dishes with Poly-L-lysine Solution or BSA as a Seeding Control (Optional)
NOTE: We used cell culture dishes precoated with PLL as positive loading-control surfaces to ensure that different experimental groups of tumor cells were seeded at the same number, as well as BSA-coated surfaces as negative controls.
<ol>
	<li>Under sterile conditions, to prepare PLL- or BSA-coated wells, add 300 &#181;L of PLL (0.1% w/v in H2O) or BSA (diluted at 2.5% w/v in H2O) directly to the 24-well plate and incubate overnight at 4 &#176;C.</li>
	<li>Remove solution by aspiration, gently rinse the surface with sterile PBS and air-dry the plate at room temperature in the tissue-culture hood before cell seeding. 
	NOTE: The final volumes of PLL or BSA must be adjusted according to the area of different well plates.</li>
</ol>
4. Seeding Fluorescent-labeled Tumor Cells on LN Cryosections or PLL/BSA-coated Wells
NOTE: As experimental controls, we used (1) cell culture dishes precoated with PLL or BSA and (2) consecutive sections of the same LN per experiment (see this detail in Figure 2D), where the latter will minimize regional variations in extracellular matrix (ECM) composition of each LN section, which in turn can dictate the cell adhesion rate. For the following tumor cell adhesion assay, select high quality and sequential LN cryosections.
<ol>
	<li>Gently wash the cryosections twice with PBS and rehydrate with PBS for 15 min at room temperature.</li>
	<li>Block unspecific adhesion to cryosections with 2.5% BSA for 30 min at 37 &#176;C. Use immunohistochemistry wash chambers and lamina cradles to ensure that the entire O.C.T was removed during washes and incubations.</li>
	<li>Drain the excess BSA on a dry paper towel, dry the outline of LN sections with a cotton swab and encircle the sections using a PAP pen.</li>
	<li>For the tumor cell adhesion assay, add 100 &#181;L of cell suspension (from step 2.4) to each encircled LN section or well in the 24-well PLL-coated plates and place it in a humidified chamber rack for 1-2 h at 37 &#176;C in the conventional cell culture incubator. 
	NOTE: The final volume of cell suspension needs be adjusted according to the area of different encircled LNs.</li>
	<li>Gently wash off non-adherent cells four times with PBS. Fix the remaining adherent fluorescent cells with 3.7% formaldehyde in PBS for 15 min at room temperature.</li>
</ol>
5. Manual Quantification of the Adhesive Index
NOTE: The adhesive index (i.e., tumor cells/LN mm2) was achieved using a 10X objective and manually counting the number of tumor cells, readily identified by light microscopy and confirmed by a fluorescence microscopy (Figure 2D), per lymph node areas of several independent fields (obtained using National Institute of Health&#39;s ImageJ/FIJI software).
<ol>
	<li>Use a fluorescent microscope with a 10x objective to take separate TIFF images in two channels corresponding to the bright and red-fluorescent fields (Figure 2D). Name and save these images systematically.</li>
	<li>Start ImageJ/FIJI, open the images and set the scale. It is necessary to use a calibration scale (e.g., a micrometric ruler 1 mm) (Figure 2C).</li>
	<li>Open the photo of the micrometric ruler (or a stage micrometer), select the Straight line tool and draw a straight line that defines a known distance.</li>
	<li>In the Analyze menu, select Set Scale. The Distance in pixels will be filled based on the length (in pixels) of the line drawn in step 5.3. The Known distance will be filled with the real distance (in this case, in millimeters) and the unit of length in the Unit of length field (in this case, in millimeters).</li>
	<li>Click on Global (this calibration applies to all images opened in this ImageJ/FIJI session) and press OK.</li>
	<li>Lymph node area quantification: Select the Wand tool and by double clicking, open the Wand tool settings. Set mode to 8-connected. Click in the photo and set the tolerance until select all lymph nodes in the photo and press OK. To measure the area, open Analyze | Measure (CTRL + M). The area is expressed in the units set earlier.</li>
	<li>Tumor cell quantification: Open the light microscopy/fluorescence images in FIJI software. Select Plugins | Analyze | Cell Counter | Cell Counter. Click on the photo to be quantified and press Initialize button in the cell counter window. Select counter type (1-8) and click on the cells in the photo. To initialize the next photo, press the Reset button in the cell counter window, open the new photo and repeat all steps. 
	NOTE: LN adhesion index is expressed as the number of adherent tumor cells per LN covered area (cells/mm2).</li>
</ol>

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The authors have nothing to disclose.

Lymphatic system dissemination of cancer cells requires a variety of complex cell-driven events. They initiate with cell detachment from primary tumor and the remodeling of the extracellular matrix (ECM) architecture, and are supported by persistent chemotaxis and active migration through the afferent lymphatics en route to the sentinel LNs. If cancer cells adhere and survive in LNs, they can easily spread to other secondary organs. Here we describe an easy method for rapid and low-cost functional analysis of specific ad...

Cancer metastasis is the main reason for treatment failure and the dominant life-threatening aspect of cancer. As postulated 130 years ago, the metastatic spread results when an elite of disseminated tumor cells (DTCs, the &#34;seeds&#34;) acquire specific biological abilities that allow them to evade primary sites and establish malignant growth at distant sites (the &#34;soil&#34;)1. Recently, several novel concepts regarding the &#34;seed and soil&#34; relations have emerged, such as the induction of premetastatic niches (conceptualized as a &#34;fertile soil&#34; needed for &#34;seeds&#34; to thrive), self-seeding of primary tumors by DTCs, &#34;seed&#34; dormancy at secondary organs and the parallel progression model of metastasis2.
For most solid malignancies, DTCs can reside and be detected in many mesenchymal organs, such as bone marrow and lymph nodes (LNs) in patients with or without evidence of clinical metastasis. Because tumor-draining LNs are the first location of the regional spread of DTCs, LN status is an important prognostic indicator and is often associated with adjuvant therapy decisions3. For some tumor types, the correlation between LN status and worse outcomes is strong, including head and neck4,5, breast6, prostate7, lung8, gastric9, colorectal10,11 and thyroid cancers12.
LNs are small ovoid organs of the lymphatic system, that are covered with reticular cells and enclosed with lymphatic vessels. These organs are absolutely necessary for the functioning of the immune system13. LNs act as attractant platforms for immune circulating cells, bringing the lymphocytes and antigen-presenting cells together14. However, LNs also attract circulating tumor cells. Over decades, LNs were pictured as passive routes of transportation for metastatic tumor cells. However, recent studies have indicated that tumor cells may also be guided towards LNs by chemotactic (chemokines) and/or haptotactic (extracellular matrix elements) cues secreted by the lymphatic endothelium15. As examples, overexpression of the CCR7 receptor in tumor cells facilitates the guidance of metastatic melanoma cells towards tumor-draining LNs16. In addition, extracellular LN proteins provide an adhesive scaffold for the recruitment and survival of circulating tumor cells17. In fact, tumor-draining LNs provide fertile soil for the seeding of DTCs, which can be maintained in proliferative or dormant states by specific LN microenvironmental signals18. The final fate of these LN-residing DTCs is controversial; some works suggest that these cells are passive indicators of metastatic progression19, while others propose that they are more likely founders of resistance (by self-seeding primary sites) and/or act as cellular reservoirs for metastases (spreading &#34;seeds&#34; for tertiary cancer growth)20,21. Recently, using preclinical models, it has been demonstrated that a fraction of these LN-residing DTCs actively invaded blood vessels, entered into the blood circulation and colonized the lungs21.
Considering that the presence of cancer cells in LNs is a marker for cancer aggressiveness and invasiveness, in this study, we optimized a classic method developed by Brodt22 to quantitatively measure tumor cell adhesion to LNs in vitro. The use of a fluorescence-based assay allowed us to develop a low-cost, rapid, sensitive and environmentally friendly (nonradioactive) protocol for the detection of adhesive alterations between tumor cells and LN cryosections. Using the MCF-7 breast cancer cells expressing different levels of NDRG4 gene expression and rat LN frozen sections to exemplify the method, we showed that this protocol allowed a good correlation between tumor cell adhesion to LNs in vitro and LN metastasis observed in breast cancer patients24.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15 mL Conical Tubes</td>
			<td>Corning</td>
			<td>352096</td>
			<td></td>
		</tr>
		<tr>
			<td>2-propanol</td>
			<td>Merck</td>
			<td>109634</td>
			<td></td>
		</tr>
		<tr>
			<td>Benchtop Laminar Flow</td>
			<td>Esco Cell Culture</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bin for Disc</td>
			<td>Leica</td>
			<td>14020139126</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma-Aldrich</td>
			<td>A9647-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture flask T-25 cm2</td>
			<td>Corning</td>
			<td>430372</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryostat</td>
			<td>Leica</td>
			<td>CM1860 UV</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryostat-Brush with magnet</td>
			<td>Leica</td>
			<td>14018340426</td>
			<td></td>
		</tr>
		<tr>
			<td>DiIC18 Cell Traker Dye</td>
			<td>Molecular Probes</td>
			<td>V-22885</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Life Technologies</td>
			<td>12657-029</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence microscope</td>
			<td>Nikon Eclipse 80</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Forma Series II CO2 incubator</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Formaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>252549</td>
			<td></td>
		</tr>
		<tr>
			<td>High Profile Disposable Razor</td>
			<td>Leica</td>
			<td>14035838926</td>
			<td></td>
		</tr>
		<tr>
			<td>Incubation Cube (IHC)</td>
			<td>KASVI</td>
			<td>K560030</td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted microscope</td>
			<td>Olympus</td>
			<td>CKX31</td>
			<td></td>
		</tr>
		<tr>
			<td>Isofluran 100 mL</td>
			<td>Crist&#225;lia</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Liquid Bloquer Super Pap Pen</td>
			<td>Abcam, Life Science Reagents</td>
			<td>ab2601</td>
			<td></td>
		</tr>
		<tr>
			<td>Optimal Cutting Temperature &#34;OCT&#34; compound</td>
			<td>Sakura</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-buffered Saline (PBS)</td>
			<td>Life Technologies</td>
			<td>70011-044</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-L-lysine</td>
			<td>Sigma-Aldrich</td>
			<td>P8920</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI</td>
			<td>Gibco</td>
			<td>31800-022</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological Pipettes 1 mL</td>
			<td>Jet Biofil</td>
			<td>GSP010001</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological Pipettes 10 mL</td>
			<td>Jet Biofil</td>
			<td>GSP010010</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological Pipettes 2 mL</td>
			<td>Jet Biofil</td>
			<td>GSP010002</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological Pipettes 5 mL</td>
			<td>Jet Biofil</td>
			<td>GSP010005</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological Pipettes 50 mL</td>
			<td>Jet Biofil</td>
			<td>GSP010050</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological Pipettor Easypet 3</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue-Tek cryomold</td>
			<td>Sakura</td>
			<td>4557</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan Blue 0.4%</td>
			<td>Invitrogen</td>
			<td>T10282</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Instituto Adolfo Lutz</td>
			<td>ATV</td>
			<td></td>
		</tr>
	</tbody>
</table>

quantification of tumor cell adhesion in lymph node cryosections

Tumor-draining lymph nodes (LNs) are not merely filters of tumor-produced waste. They are one of the most common regional sites of provisional residence of disseminated tumor cells in patients with different types of cancer. The detection of these LN-residing tumor cells is an important biomarker associated with poor prognosis and adjuvant therapy decisions. Recent mouse models have indicated that LN-residing tumor cells could be a substantial source of malignant cells for distant metastases. The ability to quantify the adhesivity of tumor cells to LN parenchyma is a critical gauge in experimental research that focuses on the identification of genes or signaling pathways relevant for lymphatic/metastatic dissemination. Because LNs are complex 3D structures with a variety of appearances and compositions in tissue sections depending on the plane of section, their matrices are difficult to replicate experimentally in vitro in a fully controlled way. Here, we describe a simple and inexpensive method that allows the quantification of adhesive tumor cells to LN cryosections. Using serial sections of the same LN, we adapt the classic method developed by Brodt to use nonradioactive labels and directly count the number of adhering tumor cells per LN surface area. LN-adherent tumor cells are readily identified by light microscopy and confirmed by a fluorescence-based method, giving an adhesion index that reveals the cell-binding affinity to LN parenchyma, which is suggestive evidence of molecular alterations in the affinity binding of integrins to their correlate LN-ligands.

We illustrate the assay by evaluating the LN adhesive potential of red fluorescent MCF-7 breast cancer cells expressing different levels of the NDRG4 gene (referred to as NDRG4-positive and NDRG4-negative cells), a negative modulator of beta1-integrin clustering at the cell surface24, by examining the fractions of rat LN-adherent tumor cells. Examples of the raw images of this protocol are shown in Figure 2. As observed in <strong clas...

Watch this Scientific Journal Video about Quantification of Tumor Cell Adhesion in Lymph Node Cryosections at JoVE.com

Quantification of Tumor Cell Adhesion in Lymph Node Cryosections

Here, we describe a simple and inexpensive method that allows the quantification of adhesive tumor cells to lymph node (LN) cryosections. LN-adherent tumor cells are readily identified by light microscopy and confirmed by a fluorescence-based method, giving an adhesion index that reveals the tumor cell-binding affinity to LN parenchyma.

Tumor-draining lymph nodes (LNs) are not merely filters of tumor-produced waste. They are one of the most common regional sites of provisional residence ...

quantification-of-tumor-cell-adhesion-in-lymph-node-cryosections

Research

JoVE Journal

Cancer Research

11.6K Views.  Hospital Sírio-Libanês. Here, we describe a simple and inexpensive method that allows the quantification of adhesive tumor cells to lymph node (LN) cryosections. LN-adherent tumor cells are readily identified by light microscopy and confirmed by a fluorescence-based method, giving an adhesion index that reveals the tumor cell-binding affinity to LN parenchyma.

Video: Quantification of Tumor Cell Adhesion in Lymph Node Cryosections

Lung Tumor Cell Recruitment Assay

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

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

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

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the context of a whole organism. Sophisticated techniques to generate genetic mosaics facilitate induction of visually marked, genetically defined clones surrounded by normal tissue. The clones can be analyzed through diverse molecular, cellular and omics approaches. This study describes how to generate fluorescently labeled clonal tumors of varying malignancy in the eye/antennal imaginal discs (EAD) of Drosophila larvae using the Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. It describes procedures how to recover the mosaic EAD and brain from the larvae and how to process them for simultaneous imaging of fluorescent transgenic reporters and antibody staining. To facilitate molecular characterization of the mosaic tissue, we describe a protocol for isolation of total RNA from the EAD. The dissection procedure is suitable to recover EAD and brains from any larval stage. The fixation and staining protocol for imaginal discs works with a number of transgenic reporters and antibodies that recognize Drosophila proteins. The protocol for RNA isolation can be applied to various larval organs, whole larvae, and adult flies. Total RNA can be used for profiling of gene expression changes using candidate or genome-wide approaches. Finally, we detail a method for quantifying invasiveness of the clonal tumors. Although this method has limited use, its underlying concept is broadly applicable to other quantitative studies where cognitive bias must be avoided.

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

This protocol demonstrates how to generate fluorescently marked, genetically defined clonal tumors in the Drosophila eye/antennal imaginal discs (EAD). It describes how to dissect the EAD and brain from the third instar larvae and how to process them to visualize and quantify gene expression changes and tumor invasiveness.

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the ...

Target Cell Pre-enrichment and Whole Genome Amplification for Single Cell Downstream Characterization

Rare target cells can be isolated from a high background of non-target cells using antibodies specific for surface proteins of target cells. A recently developed method uses a medical wire functionalized with anti-epithelial cell adhesion molecule (EpCAM) antibodies for in vivo isolation of circulating tumor cells (CTCs)1. A patient-matched cohort in non-metastatic prostate cancer showed that the in vivo isolation technique resulted in a higher percentage of patients positive for CTCs as well as higher CTC counts as compared to the current gold standard in CTC enumeration. As cells cannot be recovered from current medical devices, a new functionalized wire (referred to as Device) was manufactured allowing capture and subsequent detachment of cells by enzymatic treatment. Cells are allowed to attach to the Device, visualized on a microscope and detached using enzymatic treatment. Recovered cells are cytocentrifuged onto membrane-coated slides and harvested individually by means of laser microdissection or micromanipulation. Single-cell samples are then subjected to single-cell whole genome amplification allowing multiple downstream analysis including screening and target-specific approaches. The procedure of isolation and recovery yields high quality DNA from single cells and does not impair subsequent whole genome amplification (WGA). A single cell&#39;s amplified DNA can be forwarded to screening and/or targeted analysis such as array comparative genome hybridization (array-CGH) or sequencing. The device allows ex vivo isolation from artificial rare cell samples (i.e. 500 target cells spiked into 5 mL of peripheral blood). Whereas detachment rates of cells are acceptable (50 - 90%), the recovery rate of detached cells onto slides spans a wide range dependent on the cell line used (&#60;10 - &#62;50%) and needs some further attention. This device is not cleared for the use in patients.

This protocol is to recover and prepare rare target cells from a mixture with non-target background cells for molecular genetic characterization at the single-cell level. DNA quality is equal to non-treated single cells and allows for single-cell application (both screening based and targeted analysis).

Rare target cells can be isolated from a high background of non-target cells using antibodies specific for surface proteins of target cells. A recently ...

Characterization of Cell Membrane Extensions and Studying Their Roles in Cancer Cell Adhesion Dynamics

The cell membrane&#39;s extension repertoire modulates various malignant behaviors of cancer cells, including their adhesive and migratory potentials. The ability to accurately classify and quantify cell extensions and measure the effect on a cell&#39;s adhesive capacity is critical to determining how cell-signaling events impact cancer cell behavior and aggressiveness. Here, we describe the in vitro design and use of a cell extension quantification method in conjunction with an adhesion capacity assay in an established in vitro model for adrenocortical carcinoma (ACC). Specifically, we test the effects of DKK3, a putative tumor suppressor and a pro-differentiation factor, on the membrane extension phenotype of the ACC cell line, SW-13. We propose these assays to provide relatively simple, reliable, and easily interpretable metrics to measures these characteristics under various experimental conditions.

This study demonstrates the utility and ease of quantitative cell membrane extension measurement and its correlation to adhesive capacity of cells. As a representative example, we show here that Dickkopf-related protein 3 (DKK3) promotes increased lobopodia formation and cell adhesiveness in adrenocortical carcinoma cells in vitro.

The cell membrane&#39;s extension repertoire modulates various malignant behaviors of cancer cells, including their adhesive and migratory potentials. The ...

In Vivo EPR Assessment of pH, pO2, Redox Status, and Concentrations of Phosphate and Glutathione in the Tumor Microenvironment

This protocol demonstrates the capability of low-field electron paramagnetic resonance (EPR)-based techniques in combination with functional paramagnetic probes to provide quantitative information on the chemical tumor microenvironment (TME), including pO2, pH, redox status, concentrations of interstitial inorganic phosphate (Pi), and intracellular glutathione (GSH). In particular, an application of a recently developed soluble multifunctional trityl probe provides unsurpassed opportunity for in vivo concurrent measurements of pH, pO2 and Pi in Extracellular space (HOPE probe). The measurements of three parameters using a single probe allow for their correlation analyses independent of probe distribution and time of the measurements.

In Vivo EPR Assessment of pH, pO2, Redox Status, and Concentrations of Phosphate and Glutathione in the Tumor Microenvironment

Low-field (L-band, 1.2 GHz) electron paramagnetic resonance using soluble nitroxyl and trityl probes is demonstrated for assessment of physiologically important parameters in the tumor microenvironment in mouse models of breast cancer.

This protocol demonstrates the capability of low-field electron paramagnetic resonance (EPR)-based techniques in combination with functional paramagnetic ...

Live-Cell Imaging Assays to Study Glioblastoma Brain Tumor Stem Cell Migration and Invasion

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include rapid proliferation and pervasive invasion into the normal brain. Recurrence is thought to result from the presence of radio- and chemo-resistant brain tumor stem cells (BTSCs) that invade away from the initial cancerous mass and, thus, evade surgical resection. Hence, therapies that target BTSCs and their invasive abilities may improve the otherwise poor prognosis of this disease. Our group and others have successfully established and characterized BTSC cultures from GBM patient samples. These BTSC cultures demonstrate fundamental cancer stem cell properties such as clonogenic self-renewal, multi-lineage differentiation, and tumor initiation in immune-deficient mice. In order to improve on the current therapeutic approaches for GBM, a better understanding of the mechanisms of BTSC migration and invasion is necessary. In GBM, the study of migration and invasion is restricted, in part, due to the limitations of existing techniques which do not fully account for the in vitro growth characteristics of BTSCs grown as neurospheres. Here, we describe rapid and quantitative live-cell imaging assays to study both the migration and invasion properties of BTSCs. The first method described is the BTSC migration assay which measures the migration toward a chemoattractant gradient. The second method described is the BTSC invasion assay which images and quantifies a cellular invasion from neurospheres into a matrix. The assays described here are used for the quantification of BTSC migration and invasion over time and under different treatment conditions.

Here, we describe live-cell imaging techniques to quantitatively measure the migration and invasion of glioblastoma brain tumor stem cells over time and under multiple treatment conditions.

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include ...

Digital Polymerase Chain Reaction Assay for the Genetic Variation in a Sporadic Familial Adenomatous Polyposis Patient Using the Chip-in-a-tube Format

The quantitative analysis of human genetic variation is crucial for understanding the molecular characteristics of serious medical conditions, such as tumors. Because digital polymerase chain reactions (PCR) enable the precise quantification of DNA copy number variants, they are becoming an essential tool for detecting rare genetic variations, such as drug-resistant mutations. It is expected that molecular diagnoses using digital PCR (dPCR) will be available in clinical practice in the near future; thus, how to efficiently conduct dPCR with human genetic material is a hot topic. Here, we introduce a method to detect Adenomatous polyposis coli (APC) somatic mosaicism using dPCR with the chip-in-a-tube format, which allows eight dPCR reactions to be simultaneously conducted. Care should be taken when filling and sealing the reaction mixture on the chips. This article demonstrates how to avoid the over- and underestimation of positive partitions. Furthermore, we present a simple procedure for collecting the dPCR product from the partitions on the chips, which can then be used to confirm the specific amplification. We hope that this methods report will help promote the dPCR with the chip-in-a-tube method in genetic research.

Digital polymerase chain reaction (PCR) is a useful tool for the high-sensitivity detection of single nucleotide variants and DNA copy number variants. Here, we demonstrate key considerations for measuring rare variants in the human genome using digital PCR with the chip-in-a-tube format.

The quantitative analysis of human genetic variation is crucial for understanding the molecular characteristics of serious medical conditions, such as ...

In Vitro Tumor Cell Rechallenge For Predictive Evaluation of Chimeric Antigen Receptor T Cell Antitumor Function

The field of chimeric antigen receptor (CAR) T cell therapy is rapidly advancing with improvements in CAR design, gene-engineering approaches and manufacturing optimizations. One challenge for these development efforts, however, has been the establishment of in vitro assays that can robustly inform selection of the optimal CAR T cell products for in vivo therapeutic success. Standard in vitro tumor-lysis assays often fail to reflect the true antitumor potential of the CAR T cells due to the relatively short co-culture time and high T cell to tumor ratio. Here, we describe an in vitro co-culture method to evaluate CAR T cell recursive killing potential at high tumor cell loads. In this assay, long-term cytotoxic function and proliferative capacity of CAR T cells is examined in vitro over 7 days with additional tumor targets administered to the co-culture every other day. This assay can be coupled with profiling T cell activation, exhaustion and memory phenotypes. Using this assay, we have successfully distinguished the functional and phenotypic differences between CD4+ and CD8+ CAR T cells against glioblastoma (GBM) cells, reflecting their differential in vivo antitumor activity in orthotopic xenograft models. This method provides a facile approach to assess CAR T cell potency and to elucidate the functional variations across different CAR T cell products.

Here, we describe an in vitro co-culture method to recursively challenge tumor-targeted T cells, which allows for phenotypic and functional analysis of antitumor T cell activity.

The field of chimeric antigen receptor (CAR) T cell therapy is rapidly advancing with improvements in CAR design, gene-engineering approaches and ...

Analysis of Side Population in Solid Tumor Cell Lines

Cancer stem cells (CSCs) are an important cause of tumor growth, metastasis, and recurrence. Isolation and identification of CSCs are of great significance for tumor research. Currently, several techniques are used for the identification and purification of CSCs from tumor tissues and tumor cell lines. Separation and analysis of side population (SP) cells are two of the commonly used methods. The methods rely on the ability of CSCs to rapidly expel fluorescent dyes, such as Hoechst 33342. The efflux of the dye is associated with the ATP-binding cassette (ABC) transporters and can be inhibited by ABC transporter inhibitors. Methods for staining cultured tumor cells with Hoechst 33342 and analyzing the proportion of their SP cells by flow cytometry are described. This assay is convenient, fast, and cost-effective. Data generated in this assay can contribute to a better understanding of the effect of genes or other extracellular and intracellular signals on the stemness properties of tumor cells.

A convenient, fast, and cost-effective method to measure the proportion of side population cells in solid tumor cell lines is presented.

Cancer stem cells (CSCs) are an important cause of tumor growth, metastasis, and recurrence. Isolation and identification of CSCs are of great ...

Analysis of Lymph Node Volume by Ultra-High-Frequency Ultrasound Imaging in the Braf/Pten Genetically Engineered Mouse Model of Melanoma

Tyr::CreER+,BrafCA/+,Ptenlox/lox&#160;genetically engineered mice (Braf/Pten mice) are widely used as an in vivo model of metastatic melanoma. Once a primary tumor has been induced by tamoxifen treatment, an increase in metastatic burden is observed within 4-6 weeks after induction. This paper shows how Ultra-High-Frequency UltraSound (UHFUS) imaging can be exploited to monitor the increase in metastatic involvement of the inguinal lymph nodes by measuring the increase in their volume.
The UHFUS system is used to scan anesthetized mice with a UHFUS linear probe (22-55 MHz, axial resolution 40 &#181;m). B-mode images from the inguinal lymph nodes (both left and right sides) are acquired in a short-axis view, positioning the animals in dorsal recumbency. Ultrasound records are acquired using a 44 &#181;m step size on a motorized mechanical arm. Afterward, two-dimensional (2D) B-mode acquisitions are imported into the software platform for ultrasound image post-processing, and inguinal lymph nodes are identified and segmented semi-automatically in the acquired cross-sectional 2D images. Finally, a total reconstruction of the three-dimensional (3D) volume is automatically obtained along with the rendering of the lymph node volume, which is also expressed as an absolute measurement.
This non-invasive in vivo technique is very well tolerated and allows the scheduling of multiple imaging sessions on the same experimental animal over 2 weeks. It is, therefore, ideal to assess the impact of pharmacological treatment on metastatic disease.

Melanoma is a very aggressive disease that quickly spreads to other organs. This protocol describes the application of ultra-high-frequency ultrasound imaging, coupled with 3D rendering, to monitor the volume of the inguinal lymph nodes in the Braf/Pten mouse model of metastatic melanoma.

Tyr::CreER+,BrafCA/+,Ptenlox/lox&#160;genetically engineered mice (Braf/Pten mice) are widely used as an in vivo model of metastatic melanoma. Once a ...