Name: a three-dimensional model of spheroids to study colon cancer stem cells
Uploaded: 2021-01-22T13:00:00
Description: Watch this Scientific Journal Video about A Three-dimensional Model of Spheroids to Study Colon Cancer Stem Cells at JoVE.com

We acknowledge the imaging and Anipath recherche histology platforms (CRCL, CLB). We are indebted to the pharmacy of the Centre L&#233;on B&#233;rard (CLB) Hospital for the kind gift of FOLFOX and FOLFIRI. We also thank Brigitte Manship for critical reading of the manuscript. The work was supported by the FRM (Equipes FRM 2018, DEQ20181039598) and by the Inca (PLBIO19-289). MVG and LC received support from the FRM and CF received support from ARC foundation and the Centre L&#233;on B&#233;rard.

NOTE: The details of all reagents and materials are listed in the Table of Materials.
1. Spheroid formation
<ol>
	<li>Spheroid culture media
	<ol>
		<li>Prepare basal medium consisting of Dulbecco&#39;s Modified Eagle Medium (DMEM) supplemented with 4 mM L-alanyl-L-glutamine dipeptide.</li>
		<li>Prepare DMEM complete medium containing 10% fetal bovine serum (FBS) and 1% penicillin-streptomycin (Pen/Strep) in basal medium from step 1.1.1.</li>
		<li>Prepare DMEM/basement mem...

<ol>
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In vitro 3D models overcome the main experimental drawbacks of 2D cancer cell cultures, as they appear to be more reliable in recapitulating typical tumoral features including microenvironment and cell heterogeneity. Commonly used 3D models of spheroids are scaffold-free (cultured in low-attachment conditions) or scaffold-based (using biomaterials to culture cells). These methods present different disadvantages as they depend on the nature of the scaffold used or give rise to spheroids that are variable in structure and ...

Colorectal cancer (CRC) remains the second leading cause of cancer-associated deaths in the world1. The development of CRC is the result of a progressive acquisition and accumulation of genetic mutations and/or epigenetic alterations2,3, including the activation of oncogenes and inactivation of tumor suppressor genes3,4. Moreover, non-genetic factors (e.g., the microenvironment) can contribute to and promote oncogenic transformation and thus participate in the evolution of CRCs5. Importantly, CRCs are composed of different cell populations, including undifferentiated CSCs and bulk tumor cells displaying some differentiation traits, which constitute a hierarchical structure reminiscent of the organization of the epithelium in a normal colon crypt6,7.
CSCs are considered to be responsible for tumor appearance8, its maintenance and growth, metastatic capacity, and resistance to conventional therapies6,7. Within tumors, cancer cells, including CSCs, display a high level of heterogeneity and complexity in terms of their distinct mutational and epigenetic profiles, morphological and phenotypic differences, gene expression, metabolism, proliferation rates, and metastatic potential9. Therefore, to better understand cancer biology, tumor progression, and acquisition of resistance to therapy and its translation into effective treatments, human preclinical models capturing this cancer heterogeneity and hierarchy are important10,11.
In vitro 2D cancer cell lines have been used for a long time and provide valuable insights into tumor development and the mechanisms underlying the efficacy of therapeutic molecules. However, their limitation with respect to the lack of the phenotypic and genetic heterogeneity found in the original tumors is now widely recognized12. Moreover, nutrients, oxygen, pH gradients, and the tumor microenvironment are not reproduced, the microenvironment being especially important for the maintenance of different cell types including CSCs11,12. To overcome these main drawbacks, several 3D models have been developed to experimentally address and reproduce the complexity and heterogeneity of cancers. In effect, these models recapitulate tumor cellular heterogeneity, cell-cell interactions, and spatial architecture, similar to those observed in vivo12,13,14. Primary tumor organoids established from fresh tumors, as well as cell line-derived spheroids, are largely employed15,16.
Spheroids can be cultured in a scaffold-free or scaffold-based manner to force the cells to form and grow in cell aggregates. Scaffold-free methods are based on the culture of cells under non-adherent conditions (e.g., the hanging-drop method or ultra-low attachment plates), whereas scaffold-based models rely on natural, synthetic, or hybrid biomaterials to culture cells12,13,14. Scaffold-based spheroids present different disadvantages as the final spheroid formation will depend on the nature and composition of the (bio)material used. Although the scaffold-free spheroid methods available so far do not rely on the nature of the substrate, they generate spheroids that vary in structure and size17,18.
This work was aimed at designing a robust and reproducible 3D culture system of spheroids, which are homogenous in size, composed of Caco2 colon adenocarcinoma cells to study CSC biology. Caco2 cells are of particular interest owing to their capacity to differentiate over time19,20, strongly suggesting a stem-like potential. Accordingly, long-term culture of the spheroids revealed the presence of different CSC populations with different responses to chemotherapy.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>37 &#181;m Reversible Strainer, Large&#160;</td>
			<td>STEMCELL Technologies</td>
			<td>27250</td>
			<td>To be used with 50 mL conical tubes</td>
		</tr>
		<tr>
			<td>5-Fluorouracil</td>
			<td>Gift from Pharmacy of the Centre Leon Berard (CLB)</td>
			<td>-</td>
			<td>stock solution, 5 mg/100 mL; final concentration, 50 &#181;g/mL</td>
		</tr>
		<tr>
			<td>Agarose&#160;</td>
			<td>Sigma</td>
			<td>A9539</td>
			<td></td>
		</tr>
		<tr>
			<td>Aggrewell 400 24-well plates</td>
			<td>STEMCELL Technologies</td>
			<td>34411</td>
			<td>1,200 microwells per well for spheroid formation and growth</td>
		</tr>
		<tr>
			<td>Anti Caspase3 - Rabbit</td>
			<td>Cell Signaling</td>
			<td>9661</td>
			<td>dilution 1:200</td>
		</tr>
		<tr>
			<td>Anti Musashi-1 (14H1) - Rat</td>
			<td>eBioscience/Thermo Fisher</td>
			<td>14-9896-82</td>
			<td>dilution 1:500</td>
		</tr>
		<tr>
			<td>Anti-Adherence Rinsing Solution x 100 mL</td>
			<td>STEMCELL Technologies</td>
			<td>07010</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-CD133 (13A4) - Rat</td>
			<td>Invitrogen</td>
			<td>14-133-82</td>
			<td>dilution 1:100</td>
		</tr>
		<tr>
			<td>Anti-CD44 -Rabbit</td>
			<td>Abcam</td>
			<td>ab157107</td>
			<td>dilution 1:2000</td>
		</tr>
		<tr>
			<td>Anti-PCNA - Mouse</td>
			<td>Dako</td>
			<td>M0879</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr>
			<td>Anti-&#946;-catenin - Mouse</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-7963</td>
			<td>dilution 1:50</td>
		</tr>
		<tr>
			<td>Black multiwell plates</td>
			<td>Thermo Fisher Scientific</td>
			<td>237108</td>
			<td></td>
		</tr>
		<tr>
			<td>Citric Acid Monohydrate</td>
			<td>Sigma</td>
			<td>C1909</td>
			<td></td>
		</tr>
		<tr>
			<td>CLARIOstar apparatus&#160;</td>
			<td>BMG Labtech</td>
			<td></td>
			<td>microplate reader</td>
		</tr>
		<tr>
			<td>Dako pen</td>
			<td></td>
			<td></td>
			<td>marker pen to mark circles on slides for creating barriers for liquids</td>
		</tr>
		<tr>
			<td>Donkey anti-Mouse IgG (H+L) Secondary Antibody, Alexa Fluor 488</td>
			<td>Thermo Fisher Scientific</td>
			<td>A21202</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr>
			<td>Donkey anti-Mouse IgG (H+L) Secondary Antibody, Alexa Fluor 568</td>
			<td>Thermo Fisher Scientific</td>
			<td>A10037</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr>
			<td>Donkey anti-Rabbit IgG (H+L) Highly Cross-Adsorbed Secondary Antibody, Alexa Fluor 488</td>
			<td>Thermo Fisher Scientific</td>
			<td>A21206</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr>
			<td>Donkey anti-Rabbit IgG (H+L) Highly Cross-Adsorbed Secondary Antibody, Alexa Fluor 568</td>
			<td>Thermo Fisher Scientific</td>
			<td>A10042</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium (DMEM) Glutamax (L-alanyl-L-glutamine dipeptide)</td>
			<td>Gibco</td>
			<td>10569010</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Gibco</td>
			<td>16000044</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorogel mounting medium with DAPI</td>
			<td>Interchim</td>
			<td>FP-DT094B</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-Rat IgG (H+L) Cross-Adsorbed Secondary Antibody, Alexa Fluor 568</td>
			<td>Thermo Fisher Scientific</td>
			<td>A11077</td>
			<td>dilution 1:1000</td>
		</tr>
		<tr>
			<td>ImageJ software</td>
			<td></td>
			<td></td>
			<td>Spheroid image analysis</td>
		</tr>
		<tr>
			<td>Irinotecan&#160;</td>
			<td>Gift from Pharmacy CLB</td>
			<td>-</td>
			<td>stock solution, 20 mg/mL; final concentration, 100 &#181;g/mL</td>
		</tr>
		<tr>
			<td>iScript reverse transcriptase&#160;</td>
			<td>Bio-Rad</td>
			<td>1708891</td>
			<td></td>
		</tr>
		<tr>
			<td>Leucovorin</td>
			<td>Gift from Pharmacy CLB</td>
			<td>-</td>
			<td>stock solution, 50 mg/mL; final concentration, 25 &#181;g/mL</td>
		</tr>
		<tr>
			<td>Matrigel Basement Membrane Matrix</td>
			<td>Corning</td>
			<td>354234</td>
			<td>Basement membrane matrix</td>
		</tr>
		<tr>
			<td>Nucleospin RNA XS Kit</td>
			<td>Macherey-Nagel</td>
			<td>740902 .250</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxaliplatin</td>
			<td>Gift from Pharmacy CLB</td>
			<td>-</td>
			<td>stock solution, 100 mg/20 mL;final concentration, 10 &#181;g/mL</td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin</td>
			<td>Gibco</td>
			<td>15140130</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffer Saline (PBS)</td>
			<td>Gibco</td>
			<td>14190250</td>
			<td></td>
		</tr>
		<tr>
			<td>SYBR qPCR Premix Ex Taq II (Tli RNaseH Plus)</td>
			<td>Takara</td>
			<td>RR420B</td>
			<td></td>
		</tr>
		<tr>
			<td>SYTOX- Green</td>
			<td>Thermo Fisher Scientific</td>
			<td>S7020</td>
			<td>nucleic acid stain; dilution 1:5000</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.05&#160;%)</td>
			<td>Gibco</td>
			<td>25300062</td>
			<td></td>
		</tr>
		<tr>
			<td>Zeiss-Axiovert microscope</td>
			<td></td>
			<td></td>
			<td>inverted microscope for acquiring images of spheroids</td>
		</tr>
	</tbody>
</table>

a three-dimensional model of spheroids to study colon cancer stem cells

Colorectal cancers are characterized by heterogeneity and a hierarchical organization comprising a population of cancer stem cells (CSCs) responsible for tumor development, maintenance, and resistance to drugs. A better understanding of CSC properties for their specific targeting is, therefore, a pre-requisite for effective therapy. However, there is a paucity of suitable preclinical models for in-depth investigations. Although in vitro two-dimensional (2D) cancer cell lines provide valuable insights into tumor biology, they do not replicate the phenotypic and genetic tumor heterogeneity. In contrast, three-dimensional (3D) models address and reproduce near-physiological cancer complexity and cell heterogeneity. The aim of this work was to design a robust and reproducible 3D culture system to study CSC biology. The present methodology describes the development and optimization of conditions to generate 3D spheroids, which are homogenous in size, from Caco2 colon adenocarcinoma cells, a model that can be used for long-term culture. Importantly, within the spheroids, the cells which were organized around lumen-like structures, were characterized by differential cell proliferation patterns and by the presence of CSCs expressing a panel of markers. These results provide the first proof-of-concept for the appropriateness of this 3D approach to study cell heterogeneity and CSC biology, including the response to chemotherapy.

As the lack of homogeneity in the size of spheroids is one of the main drawbacks of currently available 3D spheroid culture systems13, the aim of this work was to set up a reliable and reproducible protocol to obtain homogenous spheroids. First, to establish ideal working conditions, different numbers of Caco2 cells were tested, ranging from 50 to 2,000 cells per microwell/spheroid using dedicated plates (Table 1). In effect, each well in these pla...

Watch this Scientific Journal Video about A Three-dimensional Model of Spheroids to Study Colon Cancer Stem Cells at JoVE.com

A Three-dimensional Model of Spheroids to Study Colon Cancer Stem Cells

This protocol presents a novel, robust, and reproducible culture system to generate and grow three-dimensional spheroids from Caco2 colon adenocarcinoma cells. The results provide the first proof-of-concept for the appropriateness of this approach to study cancer stem cell biology, including the response to chemotherapy.

Colorectal cancers are characterized by heterogeneity and a hierarchical organization comprising a population of cancer stem cells (CSCs) responsible for ...

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Longitudinal Morphological and Physiological Monitoring of Three-dimensional Tumor Spheroids Using Optical Coherence Tomography

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