Name: mammary epithelial and endothelial cell spheroids as a potential functional in vitro model for breast cancer research
Uploaded: 2021-07-12T15:00:00
Description: Watch this Scientific Journal Video about Mammary Epithelial and Endothelial Cell Spheroids as a Potential Functional In vitro Model for Breast Cancer Research at JoVE.com

This research was supported by Cancer Research Foundation / Swiss Cancer League grant KFS-4125-02-2017 to RKD and National Institute of Health grant DK079307 to EKJ.

1. Cell culture
NOTE: Conduct cell handling under sterile conditions.
<ol>
	<li>Human Umbilical Vein Endothelial Cells (HUVECs) subculture
	<ol>
		<li>Coat 75 cm2 flasks with collagen (5 &#181;g/cm2) (rat-tail) overnight (ON) at room temperature (RT) or 2-3 h at 37 &#176;C, rinse with water, and allow the flask to dry.</li>
		<li>Grow HUVECs in growth medium (EBM-2, Endothelial Basal Medium-2) supplemented with glutamine (1x = 2 mM), antibiotic-antimycotic solution (AA;...

Compared to 2D cell cultures, revolutionary 3D spheroid culture technology is a better and more powerful tool to reconstruct an organ&#39;s microenvironment, cell-cell interactions, and drug responses in vitro. This is the first protocol describing the formation of spheroids from multicellular (epithelial and endothelial) cell lines for breast cancer research. This protocol ensures spheroidal 3D growth of spheroids for up to 5 days, and spheroids can be examined after paraffin embedding, sectioning, and histolog...

The use of animals for experiments has limitations. Animal studies cannot accurately mimic disease progression in humans, and animals and humans do not have identical responses to pathogens. Additionally, restrictions in animal experimentation due to concerns for animal suffering and ethical problems1,2 increasingly constrain research programs. In vitro systems have been widely developed to circumvent the use of animals; moreover, the use of human cells has made in vitro models more relevant for the pathophysiological and therapeutic investigation. Conventional monolayer (2D) cell cultures are widely used because they mimic human tissues to some degree. However, 2D monocultures fail to mimic human organs, and 2D monocultures are unable to simulate the complex microenvironment of the original organs and mimic the in vivo situation3,4,5,6. Additionally, in monolayer cell cultures, drug treatments could easily destroy/damage all of the cells. Importantly, some of these limitations can be overcome by switching to multilayer three-dimensional (3D) cell cultures7,8. In fact, 3D culture models have been shown to better reflect the cellular structure, layout, and function of cells in primary tissues. These 3D cultures can be formed using a variety of cell lines, similar to a functional organ. Indeed, there are two models of 3D cultures. One model produces spheroids of aggregated cells that form clusters and reorganize them into spheres (scaffold-free models). The second yields organoids, which have a more complex structure and consist of combinations of multiple organ-specific cells, which are considered as a miniature version of organs9,10. Due to this, 3D culture systems represent an innovative technology with many biological and clinical applications. Thus, spheroids and organoids have numerous applications for disease modeling and studies related to regenerative medicine, drug screening, and toxicological studies6,11,12,13,14,15. Carcinogenic spheroids, derived from 3D technology, recreate the morphology and phenotype of relevant cell types, mimic the in vivo tumor microenvironment, and model cell communications and signaling pathways that are operational during tumor development16,17,18. In addition, to improve cancer biology understanding, tumor spheroids/organoids can also be used to identify a potential patient-specific anti-cancer therapy (personalized) and assess its efficacy, toxicity, and long-term effects19,20,21,22. Spheroids have opened prominent opportunities to investigate pathophysiology, disease modeling and drug screening because of their ability to preserve cellular and three-dimensional tissue architecture, the ability to mimic the in vivo situation, and the cell-cell interactions. However, one must also be aware of the limitations of this system, such as the lack of vascular/systemic component, functional immune or nervous system, and the system represents a reductionist approach as compared to animal models. Indeed, in contrast to animal models, 3D structures provide only an approximation of the biology within a human body. Understanding the limitations of the 3D method may help researchers to design more refined and valid processes for producing spheroids that better represent an organ at a larger scale23,24,25.
Cancer is the leading cause of death worldwide, and breast cancer is the most common cancer in women26,27,28. To mimic the complex microenvironment of breast cancer, breast cancer spheroids should be cultured using cells that play a prominent role in breast tumors, i.e., epithelial cells, endothelial cells, fibroblasts, and/or immune cells. Moreover, for a spheroid representing breast cancer, the expression of female hormone receptors (estrogen/progesterone receptors), ability to conserve the patient tumor histological status, and ability to mimic response to therapy should also be considered. Studies have shown that 3D co-culture systems have a cellular organization similar to that of the primary tissue in vivo, have the capability to react in real-time to stimuli, and have functional androgen receptors29,30,31,32. Hence, a similar approach could be useful to mimic a breast tumor in vitro. The purpose of the current protocol is to establish a new method of generating breast cancer spheroids. This method utilizes estrogen receptor-positive MCF-7 cells (an immortalized human cell line of epithelial cells) and vascular endothelial cells (HUVECs) or lymphatic endothelial cells (HMVEC-DNeo) to create a model that mimics or closely reflects the interactions between these cells within a tumor. Although MCF-7 (estrogen-responsive) and endothelial cells have been used to develop spheroids in the present study, other cells such as fibroblasts which represent ~80% of the breast tumor mass, could also be combined in the future to better represent and mimic breast tumor.
There are several methods to form spheroids, such as: 1) the hanging droplet method that employs gravity33,34; 2) the magnetic levitation method that uses magnetic nanoparticles exposed to an external magnet35, and 3) the spheroid microplate method that is performed by seeding cells on low-attachment plates36,37. On the basis of the existing methods, which use only one cell type, the present protocol has been optimized using epithelial and endothelial cells to better mimic the growth conditions of breast cancer tumors in vivo38,39,40,41. This method can be easily achieved in the laboratory at a low cost and with minimal equipment requirements. Based on the need/goals of the lab, different approaches were used to form spheroids and gain relevant cellular material from these spheroids. In this context, for DNA, RNA, or protein analysis, the 3D spheroids are produced by co-culturing endothelial and epithelial cells with the hanging drop method. However, for functional studies, for example, to monitor cell growth after short interfering (siRNA) transfection and/or hormone treatment, the spheroids are generated using U-bottom plates.
The purpose of this technical protocol is to provide a detailed step-by-step description for 1) forming breast cancer multicellular-type spheroids, 2) preparing samples for histological staining, and 3) collection of cells for extraction of RNA, DNA, and proteins. Both the inexpensive hanging drop method and the more expensive U-bottom plates are used to form spheroids. Here, a protocol for preparing (fixing) spheroids for sectioning and subsequent immunostaining with markers to assess cell proliferation, apoptosis, and distribution of epithelial and endothelial cells within a spheroid is provided. Additionally, this protocol shows a complete step-by-step analysis of histological data using ImageJ software. Interpretation of biological data varies depending on the type of experiment and the antibodies used. Sectioning of fixed spheroids and subsequent staining of the sections was performed by a routine pathology lab (Sophistolab: info@sophistolab.ch)

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>100 mm &#215; 20 mm tissue-culture treated culture dishes</td>
			<td>Corning</td>
			<td>CLS430167</td>
			<td></td>
		</tr>
		<tr>
			<td>149MULTI0C1</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>35 x 10 mm Tissue Culture Dish</td>
			<td>Falcon</td>
			<td>353001</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL Serological Pipet, Polystyrene, Individually Packed, Sterile</td>
			<td>Falcon</td>
			<td>357543</td>
			<td></td>
		</tr>
		<tr>
			<td>Adobe Photoshop</td>
			<td></td>
			<td></td>
			<td>Version: 13.0.1 (64-bit)</td>
		</tr>
		<tr>
			<td>Antibiotic Antimycotic Solution (100&#215;)</td>
			<td>Sigma-Aldrich</td>
			<td>A5955</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcein-AM</td>
			<td>Sigma-Aldrich</td>
			<td>17783</td>
			<td></td>
		</tr>
		<tr>
			<td>CD31 (cluster of differentiation 31)</td>
			<td>Cell Marque</td>
			<td>131M-95</td>
			<td>monoclonal mouse ab clone JC70</td>
		</tr>
		<tr>
			<td>CellTracker Green CMFDA (5-chloromethylfluorescein diacetate)</td>
			<td>Invitrogen</td>
			<td>C7025</td>
			<td></td>
		</tr>
		<tr>
			<td>CK8/18 (cytokeratins 8 and 18)</td>
			<td>DBS</td>
			<td>Mob189-05</td>
			<td>monoclonal mouse ab, clone 5D3</td>
		</tr>
		<tr>
			<td>CKX41 Inverted Microscope</td>
			<td>Olympus Life Science</td>
			<td></td>
			<td>Olympus DP27 digital camera</td>
		</tr>
		<tr>
			<td>Cleaved Caspase 3</td>
			<td>Cell Signaling</td>
			<td>9661L</td>
			<td>polyclonal rabbit ab</td>
		</tr>
		<tr>
			<td>Collagen (rat tail)</td>
			<td>Roche</td>
			<td>11 179 179 001</td>
			<td></td>
		</tr>
		<tr>
			<td>Coulter ISOTON II Diluent</td>
			<td>Beckman Coulter</td>
			<td>844 80 11</td>
			<td>Diluent II</td>
		</tr>
		<tr>
			<td>Coulter Z1, Cell Counter</td>
			<td>Coulter Electronics, Luton, UK</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dehydrated Culture Media: Noble Agar</td>
			<td>BD Difco</td>
			<td>BD 214220</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide (DMSO)</td>
			<td>Sigma-Aldrich</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#8217;s Modified Eagle&#8217;s Medium/Nutrient Mixture F-12 Ham</td>
			<td>Sigma-Aldrich</td>
			<td>D6434</td>
			<td></td>
		</tr>
		<tr>
			<td>EBM-2 Endothelial Cell Growth Basal Medium-2</td>
			<td>Lonza</td>
			<td>190860</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethidium homodimer</td>
			<td>Sigma-Aldrich</td>
			<td>46043</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Calf Serum (FCS)</td>
			<td>Thermo Fisher Scientific</td>
			<td>SH30070</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Calf Serum Charcoal Stripped (FCS sf)</td>
			<td>Thermo Fisher Scientific</td>
			<td>SH3006803</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence stereo microscopes Leica M205 FA</td>
			<td>Leica Microsystems</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GlutaMAX Supplement (100x)</td>
			<td>Gibco</td>
			<td>35050038</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS, no calcium, no magnesium, no phenol red</td>
			<td>Gibco</td>
			<td>14175053</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst 33342</td>
			<td>Life Technologies</td>
			<td>H3570</td>
			<td></td>
		</tr>
		<tr>
			<td>HUVEC &#8211; Human Umbilical Vein Endothelial Cells</td>
			<td>Lonza</td>
			<td>CC-2517</td>
			<td></td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>National Institute of Health, USA</td>
			<td></td>
			<td>Wayne Rasband 
			Version: 1.52a (64-bit)</td>
		</tr>
		<tr>
			<td>Ki67</td>
			<td>Cell Marque</td>
			<td>275R-16</td>
			<td>monoclonal rabbit ab, clone SP6</td>
		</tr>
		<tr>
			<td>Leica Histocore Multicut Rotary Microtome</td>
			<td></td>
			<td>149MULTI0C1</td>
			<td></td>
		</tr>
		<tr>
			<td>Low Serum Growth Supplement Kit (LSGS Kit)</td>
			<td>Gibco</td>
			<td>S003K</td>
			<td></td>
		</tr>
		<tr>
			<td>MCF-7 cells &#8211; human breast adenocarcinoma cell line</td>
			<td>Clinic for Gynecology, University Hospital Zurich</td>
			<td></td>
			<td>Provived from Dr Andr&#232; Fedier obtained from ATCC</td>
		</tr>
		<tr>
			<td>Nunclon Sphera 96U-well plate</td>
			<td>Thermo Fisher Scientific</td>
			<td>174925</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde (PFA)</td>
			<td>Sigma-Aldrich</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline (PBS) 1x</td>
			<td>Gibco</td>
			<td>10010015</td>
			<td></td>
		</tr>
		<tr>
			<td>Pierce BCA Protein Assay Kit</td>
			<td>Thermo Scientific</td>
			<td>23225</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein Lysis Buffer</td>
			<td>Cell Signaling, Danvers, USA</td>
			<td>9803</td>
			<td></td>
		</tr>
		<tr>
			<td>Quick-RNA Miniprep Kit</td>
			<td>Zymo Research</td>
			<td>R1055</td>
			<td></td>
		</tr>
		<tr>
			<td>RNA Lysis Buffer</td>
			<td>Zymo Research</td>
			<td>R1060-1-100</td>
			<td>Contents in Quick-RNA Miniprep Kit</td>
		</tr>
		<tr>
			<td>Rotina 46R Centrifuge</td>
			<td>Hettich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Round-Bottom Polystyrene Tubes, 5 mL</td>
			<td>Falcon</td>
			<td>352003</td>
			<td></td>
		</tr>
		<tr>
			<td>Sonicator</td>
			<td>Bandelin electronics, Berlin, DE</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tecan Infinite series M200 microplate reader</td>
			<td>Tecan, Salzburg, AU</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Culture Flasks 75</td>
			<td>TPP</td>
			<td>90076</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA solution</td>
			<td>Sigma-Aldrich</td>
			<td>T3924</td>
			<td></td>
		</tr>
	</tbody>
</table>

mammary epithelial and endothelial cell spheroids as a potential functional in vitro model for breast cancer research

Breast cancer is the leading cause of mortality in women. The growth of breast cancer cells and their subsequent metastasis is a key factor for its progression. Although the mechanisms involved in promoting breast cancer growth have been intensively studied using monocultures of breast cancer cells such as MCF-7 cells, the contribution of other cell types, such as vascular and lymphatic endothelial cells that are intimately involved in tumor growth, has not been investigated in depth. Cell-cell interaction plays a key role in tumor growth and progression. Neoangiogenesis, or the development of vessels, is essential for tumor growth, whereas the lymphatic system serves as a portal for cancer cell migration and subsequent metastasis. Recent studies provide evidence that vascular and lymphatic endothelial cells can significantly influence cancer cell growth. These observations imply a need for developing in vitro models that would more realistically reflect breast cancer growth processes in vivo. Moreover, restrictions in animal research require the development of ex vivo models to elucidate better the mechanisms involved.
This article describes the development of breast cancer spheroids composed of both breast cancer cells (estrogen receptor-positive MCF-7 cells) and vascular and/or lymphatic endothelial cells. The protocol describes a detailed step-by-step approach in creating dual-cell spheroids using two different approaches, hanging drop (gold standard and cheap) and 96-well U-bottom plates (expensive). In-depth instructions are provided for how to delicately pick up the formed spheroids to monitor growth by microscopic sizing and assessing viability using dead and live cell staining. Moreover, procedures to fix the spheroids for sectioning and staining with growth-specific antibodies to differentiate growth patterns in spheroids are delineated. Additionally, details for preparing spheroids with transfected cells and methods to extract RNA for molecular analysis are provided. In conclusion, this article provides in-depth instructions for preparing multi-cell spheroids for breast cancer research.

The spheroids model using epithelial and endothelial co-cultures is required to closely mimic in vivo conditions of breast tumors for in vitro experiments. The scheme in Figure 1 depicts the protocol to form spheroids with breast cancer epithelial cells and vascular or lymphatic endothelial cells (Figure 1). Each cell type is seeded separately in a 3.5 cm round dish and treated with growth stimulators/inhibitors or transfected with oligonucleot...

Watch this Scientific Journal Video about Mammary Epithelial and Endothelial Cell Spheroids as a Potential Functional In vitro Model for Breast Cancer Research at JoVE.com 

Mammary Epithelial and Endothelial Cell Spheroids as a Potential Functional In vitro Model for Breast Cancer Research (Video) | JoVE 

Crosstalk between mammary epithelial cells and endothelial cells importantly contributes to breast cancer progression, tumor growth, and metastasis. In this study, spheroids have been made from breast cancer cells together with vascular and/or lymphatic endothelial cells and demonstrate their applicability as an in vitro system for breast cancer research.

Mammary Epithelial and Endothelial Cell Spheroids as a Potential Functional In vitro Model for Breast Cancer Research

Breast cancer is the leading cause of mortality in women. The growth of breast cancer cells and their subsequent metastasis is a key factor for its ...

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