This research was supported by the &#8220;Establishment of measurement standards for Chemistry and Radiation&#8221;, grant number KRISS-2020-GP2020-0003, and &#8220;Development of Measurement Standards and Technology for Biomaterials and Medical Convergence&#8221;, grant number KRISS-2020-GP2020-0004 programs, funded by the Korea Research Institute of Standards and Science. This research was also supported by the Ministry of Science and ICT (MSIT), National Research Foundation of Korea (NRF-2019M3A9F3065868), The Ministry of Health and Welfare (MOHW), the Korea Health Industry Development Institute (KHIDI, HI20C0558), the Ministry of Trade, Industry &#38; Energy (MOTIE), and Korea Evaluation Institute of Industrial Technology (KEIT, 20009350). ORCID ID (Hee Min Yoo: 0000-0002-5951-2137; Dukjin Kang: 0000-0002-5924-9674; Seil Kim: 0000-0003-3465-7118; Joo-Eun Lee: 0000-0002-2495-1439; Jina Lee: 0000-0002-3661-3701).&#160;We thank Chang Woo Park for assistance with experiments.

1. Bacterial cell cultures and preparation of Lactobacillus&#160; cell-free supernatant (LCFS)
NOTE: Steps 1.2 &#8211; 1.9 are conducted in an anaerobic chamber.
<ol>
	<li>Prepare an MRS agar plate and broth containing L-cysteine and sterilize by autoclaving.</li>
	<li>Pre-incubate the MRS agar plate in H2 anaerobic chamber maintained at 37 &#730;C with 20 ppm oxygen.</li>
	<li>Thaw Lactobacillus bacterial stock and inoculate the agar plate with the bacterial culture (Figure 1A (i)).</li>
	<li>Incubate bacteria for 2 - 3 days in H2 anaerobic chamber at 37 &#730;C and 20 ppm oxygen until single bacterial colonies are obtained.</li>
	<li>Wash and dry the Hungate type anerobic culture tube. Autoclave the culture tube at 121 &#730;C for 15 min.</li>
	<li>Then incubate the tube in H2 anaerobic chamber at 37 &#730;C and 20 ppm oxygen to remove oxygen.</li>
	<li>Place 2 - 3 mL of MRS broth into the tube. Seal the tube with a butyl rubber stopper and screw the cap.</li>
	<li>Obtain a single colony with a loop and place it into the 1.5 mL culture tube with 500 &#181;L of 1x PBS. (Figure 1A (ii)).</li>
	<li>Suspend the colony using a 1 mL syringe (Figure 1A (iii)). Do this by, inserting the needle of the 1 mL syringe in the center of the tube lid, aspirating the suspended colony and then resuspending it back into the MRS broth media. (Figure 1A (iv)).</li>
	<li>Incubate the MRS broth media in a shaker incubator for 2 days (37 &#176;C, 5% CO2, 200 rpm).</li>
	<li>Measure the optical density (OD) using a spectrophotometer to monitor bacterial growth curves until the absorbance at OD620 reaches to 2.0.</li>
	<li>Separate the bacterial pellets and the conditioned media by centrifuging at 1,000 x g for 15 min. Wash the collected bacterial pellets with 1x PBS and resuspend in 4 mL of RPMI 1640 supplemented with 10% fetal bovine serum. Do not include any antibiotics in the medium.</li>
	<li>Maintain the bacterial pellets in RPMI and incubate in a shaker incubator for 4 h at 37 &#176;C with 5% CO2 at a speed of 100 rpm.</li>
	<li>For the preparation of the probiotic supernatant, remove the bacterial pellet via centrifugation at 1000 x&#160;g, for 15 min at 4 &#176;C. Sterile-filter the recovered supernatant using a 0.22 &#956;m filter and store at &#8722;80 &#176;C until use.</li>
</ol>
2. Generation of spheroids
<ol>
	<li>Preparing colorectal cancer cell lines
	<ol>
		<li>Grow DLD-1, HT-29, and WiDr cell lines as monolayers until 70-80% confluency and incubate the plate at 37 &#176;C in a 5% CO2 incubator (Growth medium: RPMI containing 10% fetal bovine serum (FBS) and 1% penicillin-streptomycin).</li>
		<li>For cells grown in 100 mm Petri dish, wash the plate twice with 4 mL of 1x PBS. Add 1 mL of 0.25% trypsin-EDTA and incubate the Petri dish for 2 min at 37 &#176;C in a 5% CO2 incubator to dissociate the cells.</li>
		<li>After incubation, check for the cell dissociation under a microscope and neutralize trypsin-EDTA with 5 mL of growth medium.</li>
		<li>Transfer the dissociated cells to a 15 mL conical tube and centrifuge for 3 min at 300 x&#160;g.</li>
		<li>Discard the supernatant and resuspend gently with 3 mL of growth media.</li>
		<li>Count the cells with trypan blue to determine viable cells using a hemocytometer. (Figure 1B (i))</li>
	</ol>
	</li>
	<li>Spheroid formation
	<ol>
		<li>In a 15 mL conical tube, dilute the cells from 2.1.5 to obtain 1 - 2 x 105 cells/mL (Figure 1B (ii))</li>
		<li>Add final concentration of 0.6% methylcellulose to the cell suspension and transfer the diluted cells to a sterile reservoir. 
		NOTE: For each cell line, the amount of methylcellulose needed should be titrated and determined accordingly.</li>
		<li>Use a multichannel pipette to dispense 200 &#181;L of cells to each well of an ultra-low attachment 96-well round bottom microplate. (Figure 1B (iii))</li>
		<li>Incubate the plate at 37 &#176;C in a 5% CO2 incubator for 24 - 36 h.</li>
		<li>After 24 - 36 h, observe the plate under a light microscope to ensure spheroid formation.</li>
	</ol>
	</li>
</ol>
3. Treating 3D colorectal cancer cells with LCFS
<ol>
	<li>Generate spheroids as described in steps 2 and 3.</li>
	<li>Before performing the LCFS treatment, thaw the frozen LCFS at room temperature (RT) for 10 - 20 min.</li>
	<li>Inoculate the LCFS stock solution into a growth medium. Serially dilute to 25%, 12.5%, and 6% in the growth medium (i.e., 25% LCFS = 150 &#181;L of growth medium + 50 &#181;L of LCFS).</li>
	<li>Take out the cell culture plate containing spheroids from the incubator and remove as much of the growth medium as possible from each well using a 200 &#956;L pipette.</li>
	<li>Add the growth media with LCFS on the cells and incubate at 37 &#176;C in a 5% CO2 incubator for 24 - 48 h. 
	NOTE: The volume to be used will depend on the plate size as follows: 2 mL for 6-well cell culture plates; 200 &#956;L for 96-well cell culture plates.</li>
</ol>
4. Cell viability for spheroids
<ol>
	<li>Prepare 8 - 10 LCFS-treated colorectal cancer spheroids in opaque-walled multi-well plates (cell viability assays are performed 48 h after LCFS treatment).</li>
	<li>Thaw the cell viability reagent (see Table of Materials) at 4 &#176;C for overnight.</li>
	<li>Equilibrate the cell viability reagent to room temperature before use.</li>
	<li>Before performing the assay, remove 50% of the growth media from the spheroids.</li>
	<li>Add 100 &#181;L of cell viability reagent to each well. 
	NOTE: The volume to be used will depend on the plate size as follows: 100 &#956;L for 96-well cell culture plates.</li>
	<li>Mix the reagent vigorously for 5 min to promote cell lysis.</li>
	<li>Incubate for 30 min &#8211; 2 h at 37 &#176;C.</li>
	<li>Record the luminescence.</li>
</ol>
5. Quantitative real-time polymerase chain reaction analysis for spheroids
<ol>
	<li>For each condition, prepare 10 - 15 spheroids in a 2 mL tube and centrifuge for 3 min at 400 x g.</li>
	<li>Discard the supernatant and wash the spheroids twice in 1 mL of ice-cold 1x PBS. 
	NOTE: Avoid centrifugation, let the spheroids settle down.</li>
	<li>Aspirate as much of the 1x PBS as possible and isolate RNA using a commercially available kit.</li>
	<li>Synthesize cDNA from 1 &#956;g of RNA using a commercially available kit as per the manufacturer&#8217;s protocol.</li>
	<li>Prepare a master mix to run all samples in triplicate (see Table 1 and Table 2).</li>
	<li>Perform the amplification in a 20 &#181;L of the template master mix into each qPCR plate well.</li>
	<li>Mix reactions well and spin if necessary.</li>
	<li>Run samples as per the recommendations of the instrument manufacturer (Table 3).</li>
</ol>
6. Western blotting from spheroids
NOTE: When collecting spheroids, use a 200 &#956;L pipette and cut the end of the tips to avoid disturbing their structure.
<ol>
	<li>For each condition, prepare 30 - 40 spheroids in a 2 mL tube.</li>
	<li>Place the tube on ice and let the spheroids settle down to the bottom of the 2 mL tube.</li>
	<li>Discard the supernatant and wash the spheroids twice in 1 mL ice-cold 1x PBS 
	NOTE: Avoid centrifugation, let the spheroids settle down.</li>
	<li>Aspirate as much of the 1x PBS as possible and add RIPA buffer with a protease inhibitor cocktail (10 spheroids = 30 &#181;L of RIPA buffer).</li>
	<li>Lyse the cells by pipetting up and down and perform sonication for 30 s with 30 s of resting on ice for 10 cycles.</li>
	<li>Centrifuge the protein lysates at 15000 x g for 15 min at 4 &#176;C.</li>
	<li>Determine the protein concentration for each cell lysate.</li>
	<li>Before loading, boil each cell lysate in a sample buffer at 100 &#176;C for 10 min.</li>
	<li>Load equal amounts of protein into the wells of the SDS-PAGE gel and run the gel for 1 - 2 h at 100 V.</li>
	<li>Transfer the protein from the gel to the PVDF membrane.</li>
	<li>After transferring, block the membrane for 1 h at room temperature using a blocking buffer (5% skim milk + TBS with 0.05% Tween-20).</li>
	<li>Incubate the membrane with 1:1,000 dilutions of primary antibody (Table 4) in 1x TBST with 5% BSA buffer at 4 &#176;C overnight.</li>
	<li>Wash the membrane three times with TBST, 15 min for each wash.</li>
	<li>Incubate the membrane with 1:2,500 dilutions of secondary antibody in the blocking buffer at room temperature for 2 h (see Table of Materials).</li>
	<li>Wash the membrane three times with TBST, 15 min for each wash.</li>
	<li>Prepare the membrane for HRP detection with a chemiluminescent substrate.</li>
	<li>Acquire chemiluminescent images.</li>
</ol>
7. Propidium Iodide (PI) staining of spheroids
<ol>
	<li>Prepare 5-10 spheroids as described in Step 4.1 and place the spheroids in an incubator at 37 &#176;C and 5% CO2.</li>
	<li>Dilute a 1 mg/mL stock of PI 1:100 in 1x PBS.</li>
	<li>Remove 50% of the medium from each well of the 96-well plate.</li>
	<li>Add 100 &#181;L of the PI solution to each well and place the wells in an incubator at 37 &#176;C and 5% CO2 for 10 - 15 min.</li>
	<li>Wash out the PI solution with 1x PBS.</li>
	<li>Add 200 &#181;L of growth medium and take an image using a fluorescence microscope. Analyze the fluorescence intensity using Image J to get the viability count of the spheroid.</li>
</ol>
8. FACS analysis of spheroids
<ol>
	<li>Generate spheroids as described previously.</li>
	<li>For each condition, prepare 30 - 40 spheroids in a FACS tube and centrifuge for 3 min at 400 x g and RT.</li>
	<li>Aspirate the supernatant and wash the spheroids in 3 mL of 1x PBS, then centrifuge at 400 x&#160;g for 3 min at 4 &#176;C.</li>
	<li>Aspirate the supernatant and add 200 &#181;L of 0.25% Trypsin-EDTA, then incubate at RT for 2 -3 min. 
	NOTE: The incubation time is dependent on the spheroid size and cell type.</li>
	<li>Add 1 mL of FACS buffer and gently dissociate the spheroids using a 200 &#956;L pipette.</li>
	<li>Centrifuge the dissociated cells at 400 x&#160;g and 4 &#176;C for 3 min. 
	NOTE: FACS buffer = 1x PBS + 2.5% FBS, filtered using a 0.22 &#181;m top filter.</li>
	<li>Discard the supernatant and add 7-AAD/Annexin V reagent (7AAD (5 &#181;L), Annexin V (5 &#181;L)/sample).</li>
	<li>Gently vortex the cells and incubate for 13 - 30 min at RT in the dark.</li>
	<li>Add 500 &#181;L of FACS buffer and filter the cells using conical polystyrene test tubes to remove aggregate cells.</li>
	<li>Centrifuge at 400 x&#160;g and 4 &#176;C for 3 min.</li>
	<li>Add 500 &#181;L of Annexin V binding buffer to each tube and resuspend.</li>
	<li>Analyze using a flow cytometer.</li>
</ol>

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The authors have no relevant financial disclosures.

The tissue microenvironment, including neighboring cells and the extracellular matrix (ECM), is fundamental to tissue generation and crucial in the control of cell growth and tissue development13. However, 2D cultures have several disadvantages, such as the disruption of cellular interactions, as well as alterations in cell morphology, extracellular environments, and the approach of division14. 3D cell culture systems have been rigorously studied to better reproduce in vivo...

Probiotics are the most advantageous microorganisms in the gut that improves immune homeostasis and host energy metabolism1. Probiotics from Lactobacillus and Bifidobacterium are the most advanced of its kind found in the intestine2,3. Previous investigations have shown that Lactobacillus has inhibitory and antiproliferative effects on several cancers, including colorectal cancer4. Moreover, probiotics prevent inflammatory bowel diseases, Crohn&#8217;s disease, and ulcerative colitis5,6. However, most studies with probiotics were performed in two dimensional (2D) monolayers that are grown on solid surfaces.
Artificial culture systems lack environmental features, which is not natural for cancer cells. To overcome this limitation, three dimensional (3D) culture systems have been developed7,8. Cancer cells in 3D show improvements in terms of basic biological mechanisms, such as cell viability, proliferation, morphology, cell-cell communication, drug sensitivity, and in vivo relevance9,10. Moreover, spheroids are made from multicellular types of colorectal cancer and are dependent on cell-cell interactions and the extracellular matrix (ECM)11. Our previous study has reported that probiotic cell-free supernatant (CFS) produced using Lactobacillus fermentum showed anti-cancer effects on 3D cultures of colorectal cancer (CRC) cells12. We proposed that CFS is a suitable alternative strategy for testing probiotic effects on 3D spheroids12.
Here, we present an approach that can accommodate multicellular types of 3D colorectal cancer for the analysis of therapeutic effects of probiotic cell-free supernatant (CFS) on several 3D colorectal cancer mimicry systems. This method provides a means for the analysis of related probiotic and anti-cancer effects in vitro.

<table>
	<tbody>
		<tr>
			<td> 
			10% Mini-PROTEAN TGX Precast Protein Gels, 15-well, 15 &#181;l</td>
			<td>Biorad</td>
			<td>4561036</td>
			<td>Pkg of 10</td>
		</tr>
		<tr>
			<td>Applied Biosystems MicroAmp Optical Adhesive Film</td>
			<td>Thermo Fisher Scientific</td>
			<td>4311971</td>
			<td>100 covers</td>
		</tr>
		<tr>
			<td>10x transfer buffer</td>
			<td>Intron</td>
			<td>IBS-BT031A</td>
			<td>1 L</td>
		</tr>
		<tr>
			<td>10X Tris-Glycine (W/SDS)</td>
			<td>Intron</td>
			<td>IBS-BT014</td>
			<td>1 L</td>
		</tr>
		<tr>
			<td>Axygen 2.0 mL MaxyClear Snaplock Microcentrifuge Tube, Polypropylene, Clear, Nonsterile, 500 Tubes/Pack, 10 Packs/Case</td>
			<td>Corning</td>
			<td>SCT-200-C</td>
			<td>500 Tubes/Pack, 10 Packs/Case</td>
		</tr>
		<tr>
			<td>BD Difco Bacto Agar</td>
			<td>BD</td>
			<td>214010</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>BD Difco Lactobacilli MRS Broth</td>
			<td>BD</td>
			<td>DF0881-17-5</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>CellTiter-Glo 3D Cell viability assay</td>
			<td>Promega</td>
			<td>G9681</td>
			<td>100&#956;l/assay in 96-well plates</td>
		</tr>
		<tr>
			<td>Complete Protease Inhibitor Cocktail</td>
			<td>Sigma-Aldrich</td>
			<td>11697498001</td>
			<td>vial of 20 tablets</td>
		</tr>
		<tr>
			<td>Corning Phosphate-Buffered Saline, 1X without calcium and magnesium, PH 7.4 &#177; 0.1</td>
			<td>Corning</td>
			<td>21-040-CV</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>EMD Millipore Immobilon-P PVDF Transfer Membranes</td>
			<td>fisher Scientific</td>
			<td>IPVH00010</td>
			<td>26.5cm x 3.75m roll; Pore Size: 0.45um</td>
		</tr>
		<tr>
			<td>Falcon 5 mL Round Bottom Polystyrene Test Tube, with Cell Strainer Snap Cap</td>
			<td>Corning</td>
			<td>352235</td>
			<td>25/Pack, 500/Case</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum, certified, US origin</td>
			<td>Thermo Fisher Scientific</td>
			<td>16000044</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>iScript cDNA Synthesis Kit, 25 x 20 &#181;l rxns #1708890</td>
			<td>Biorad</td>
			<td>1708890</td>
			<td>25 x 20 &#181;L rxns</td>
		</tr>
		<tr>
			<td>iTaq Universal SYBR Green Supermix</td>
			<td>Biorad</td>
			<td>1725121</td>
			<td>5 x 1 mL</td>
		</tr>
		<tr>
			<td>Lactobacillus fermentum</td>
			<td>Korean Collection for Type Cultures</td>
			<td>KCTC 3112</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Cysteine hydrochloride monohydrate</td>
			<td>Sigma-Aldrich</td>
			<td>C6852-25G</td>
			<td>25 g</td>
		</tr>
		<tr>
			<td>Methyl Cellulose (3500-5600mPa&#183;s, 2% in Water at 20&#176;C)</td>
			<td>TCI</td>
			<td>M0185</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>MicroAmp Fast Optical 96-Well Reaction Plate with Barcode, 0.1 mL</td>
			<td>Applied Biosystems</td>
			<td>4346906</td>
			<td>20 plates</td>
		</tr>
		<tr>
			<td>Millex-GS Syringe Filter Unit, 0.22 &#181;m, mixed cellulose esters, 33 mm, ethylene oxide sterilized</td>
			<td>Millipore</td>
			<td>SLGS033SB</td>
			<td>250</td>
		</tr>
		<tr>
			<td>PE Annexin V Apoptosis Detection Kit with 7-AAD</td>
			<td>Biolegend</td>
			<td>640934</td>
			<td>100 tests</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin (10,000 U/mL)</td>
			<td>Thermo Fisher Scientific</td>
			<td>15140122</td>
			<td>100 mL</td>
		</tr>
		<tr>
			<td>Propidium Iodide</td>
			<td>Introgen</td>
			<td>P1304MP</td>
			<td>100 mg</td>
		</tr>
		<tr>
			<td>RIPA Lysis and Extraction Buffer</td>
			<td>Thermo Fisher Scientific</td>
			<td>89901</td>
			<td>250 mL</td>
		</tr>
		<tr>
			<td>RNeasy Mini Kit (250)</td>
			<td>Qiagen</td>
			<td>74106</td>
			<td>250</td>
		</tr>
		<tr>
			<td>RPMI-1640</td>
			<td>Gibco</td>
			<td>11875-119</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25%), phenol red</td>
			<td>Thermo Fisher Scientific</td>
			<td>25200056</td>
			<td>100 mL</td>
		</tr>
		<tr>
			<td>Name of Materials/Equipment/Software</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>anti - p-I&#954;B&#945; (B-9)</td>
			<td>Santa cruze</td>
			<td>sc-8404</td>
			<td>200 &#181;g/mL</td>
		</tr>
		<tr>
			<td>anti-BclxL (H-5)</td>
			<td>Santa cruze</td>
			<td>sc-8392</td>
			<td>200 &#181;g/mL</td>
		</tr>
		<tr>
			<td>anti-PARP 1 (C2-10)</td>
			<td>Santa cruze</td>
			<td>sc-53643</td>
			<td>50 &#181;l ascites</td>
		</tr>
		<tr>
			<td>anti-&#946;-actin (C4)</td>
			<td>Santa cruze</td>
			<td>sc-47778</td>
			<td>200 &#181;g/mL</td>
		</tr>
		<tr>
			<td>BD FACSVerse</td>
			<td>BD Biosciences</td>
			<td></td>
			<td>San Diego, CA, USA</td>
		</tr>
		<tr>
			<td>Synergy HTX Multi-Mode Microplate Reader</td>
			<td>BioT</td>
			<td>S1LFA</td>
			<td></td>
		</tr>
		<tr>
			<td>CO2 incubator</td>
			<td>Thermo fisher</td>
			<td>HERAcell 150i</td>
			<td></td>
		</tr>
		<tr>
			<td>Conical tube 15 ml</td>
			<td>SPL</td>
			<td>50015</td>
			<td></td>
		</tr>
		<tr>
			<td>Conical tube 50 ml</td>
			<td>SPL</td>
			<td>50050</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning Costar Ultra-Low Attachment Multiple Well Plate</td>
			<td>Sigma-Aldrich</td>
			<td>CLS7007</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning Costar Ultra-Low Attachment Multiple Well Plate</td>
			<td>Sigma-Aldrich</td>
			<td>CLS3471</td>
			<td></td>
		</tr>
		<tr>
			<td>Costar 50 mL Reagent Reservoirs, 5/Bag, Sterile</td>
			<td>Costar</td>
			<td>4870</td>
			<td></td>
		</tr>
		<tr>
			<td>Countess Cell Counting Chamber Slides</td>
			<td>Thermofisher</td>
			<td>C10228</td>
			<td></td>
		</tr>
		<tr>
			<td>Countess II FL Automated Cell Counter</td>
			<td>invitrogen</td>
			<td>AMQAF1000</td>
			<td></td>
		</tr>
		<tr>
			<td>EnSpire Multimode Reader</td>
			<td>Perkin Elmer</td>
			<td></td>
			<td>Enspire 2300</td>
		</tr>
		<tr>
			<td>Eppendorf Research Plus Multi Channel Pipette, 8-channel</td>
			<td>Eppendorf</td>
			<td>3122000051</td>
			<td></td>
		</tr>
		<tr>
			<td>FlowJo software</td>
			<td>TreeStar</td>
			<td></td>
			<td>Ashland, OR, USA</td>
		</tr>
		<tr>
			<td>Goat Anti-Mouse IgG (H+L)</td>
			<td>Jackson immunoresearch</td>
			<td>115-035-062</td>
			<td>1.5 mL</td>
		</tr>
		<tr>
			<td>Goat Anti-Rabbit IgG (H+L)</td>
			<td>Jackson immunoresearch</td>
			<td>111-035-144</td>
			<td>2.0 mL</td>
		</tr>
		<tr>
			<td>GraphPad Prism 5</td>
			<td>GraphPad Software</td>
			<td></td>
			<td>Inc., San Diego, CA, USA</td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>NIH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ImageQuant LAS 4000 mini</td>
			<td>Fujifilm</td>
			<td></td>
			<td>Tokyo, Japan</td>
		</tr>
		<tr>
			<td>Incubated shaker</td>
			<td>Lab companion</td>
			<td>SIF-6000R</td>
			<td></td>
		</tr>
		<tr>
			<td>Multi Gauge Ver. 3.0,</td>
			<td>Fujifilm</td>
			<td></td>
			<td>Tokyo, Japan</td>
		</tr>
		<tr>
			<td>Optical density (OD)LAMBDA UV/Vis Spectrophotometers</td>
			<td>Perkin Elmer</td>
			<td></td>
			<td>Waltham, MA, USA</td>
		</tr>
		<tr>
			<td>Phase-contrast microscope</td>
			<td>Olympus</td>
			<td></td>
			<td>Tokyo, Japan</td>
		</tr>
		<tr>
			<td>SPL microcentrifuge tube 1.5mL</td>
			<td>SPL</td>
			<td>60015</td>
			<td></td>
		</tr>
		<tr>
			<td>SPL Multi Channel Reservoirs, 12-Chs, PS, Sterile</td>
			<td>SPL</td>
			<td>21012</td>
			<td></td>
		</tr>
		<tr>
			<td>StepOnePlus Real-Time PCR system</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>Waltham, MA, USA</td>
		</tr>
		<tr>
			<td>Vibra-Cell Ultrasonic Liquid Processors</td>
			<td>SONICS-vibra cell</td>
			<td>VC 505</td>
			<td>500 Watt ultrasonic processor</td>
		</tr>
		<tr>
			<td>Vinyl Anaerobic Chamber</td>
			<td>COY LAB PRODUCTS</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

evaluating cell death using cell-free supernatant of probiotics in three-dimensional spheroid cultures of colorectal cancer cells

This manuscript describes a protocol to evaluate cancer cell deaths in three dimensional (3D) spheroids of multicellular types of cancer cells using supernatants from Lactobacillus fermentum cell culture, considered as probiotics cultures. The use of 3D cultures to test Lactobacillus cell-free supernatant (LCFS) are a better option than testing in 2D monolayers, especially as L. fermentum can produce anti-cancer effects within the gut. L. fermentum supernatant was identified to possess increased anti-proliferative effects against several colorectal cancer (CRC) cells in 3D culture conditions. Interestingly, these effects were strongly related to the culture model, demonstrating the notable ability of L. fermentum to induce cancer cell death. Stable spheroids were generated from diverse CRCs (colorectal cancer cells) using the protocol presented below. This protocol of generating 3D spheroid is time saving and cost effective. This system was developed to easily investigate the anti-cancer effects of LCFS in multiple types of CRC spheroids. As expected, CRC spheroids treated with LCFS strongly induced cell death during the experiment and expressed specific apoptosis molecular markers as analyzed by qRT-PCR, western blotting, and FACS analysis. Therefore, this method is valuable for exploring cell viability and evaluating the efficacy of anti-cancer drugs.

We describe the protocol of obtaining spheroids from diverse colorectal cancer cell lines. Supplementation with methylcellulose was required to generate spheroids. We also present a method of LCFS preparation and present a model to study the correlation between probiotics and colorectal cancer. Spheroid formation and LCFS preparation protocols are schematically illustrated in Figure 1A,B. As shown in Figure 2A, methylcellulose concentration of 0...

Watch this Scientific Journal Video about Evaluating Cell Death Using Cell-Free Supernatant of Probiotics in Three-Dimensional Spheroid Cultures of Colorectal Cancer Cells at JoVE.com

Evaluating Cell Death Using Cell-Free Supernatant of Probiotics in Three-Dimensional Spheroid Cultures of Colorectal Cancer Cells

Here methods are presented to understand anti-cancer effects of Lactobacillus cell-free supernatant (LCFS). Colorectal cancer cell lines show cell deaths when treated with LCFS in 3D cultures. The process of generating spheroids can be optimized depending on the scaffold and the analysis methods presented are useful for evaluating the involved signaling pathways.

This manuscript describes a protocol to evaluate cancer cell deaths in three dimensional (3D) spheroids of multicellular types of cancer cells using ...

evaluating-cell-death-using-cell-free-supernatant-probiotics-three

Research

JoVE Journal

Cancer Research

5.4K Views.  Korea Research Institute of Standards and Science (KRISS). Here methods are presented to understand anti-cancer effects of Lactobacillus cell-free supernatant (LCFS). Colorectal cancer cell lines show cell deaths when treated with LCFS in 3D cultures. The process of generating spheroids can be optimized depending on the scaffold and the analysis methods presented are useful for evaluating the involved signaling pathways.

Video: Evaluating Cell Death Using Cell-Free Supernatant of Probiotics in Three-Dimensional Spheroid Cultures of Colorectal Cancer Cells

Utilizing Functional Genomics Screening to Identify Potentially Novel Drug Targets in Cancer Cell Spheroid Cultures

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery of the next generation of novel drug targets. It is becoming apparent that more complex models of cancer are required to fully appreciate the contributing factors that drive tumorigenesis in vivo and increase the efficacy of novel therapies that make the transition from pre-clinical models to clinical trials.
Here we present a methodology for generating uniform and reproducible tumor spheroids that can be subjected to siRNA functional screening. These spheroids display many characteristics that are found in solid tumors that are not present in traditional two-dimension culture. We show that several commonly used breast cancer cell lines are amenable to this protocol. Furthermore, we provide proof-of-principle data utilizing the breast cancer cell line BT474, confirming their dependency on amplification of the epidermal growth factor receptor HER2 and mutation of phosphatidylinositol-4,5-biphosphate 3-kinase (PIK3CA) when grown as tumor spheroids. Finally, we are able to further investigate and confirm the spatial impact of these dependencies using immunohistochemistry.

Identifying novel drug targets that transition from pre-clinical testing to human trials is a scientific priority. To that end, here we describe a functional genomics approach for examining the impact of gene depletion on cancer cell line spheroids, which more appropriately model human cancers in vivo.

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery ...

Preparation and Metabolic Assay of 3-dimensional Spheroid Co-cultures of Pancreatic Cancer Cells and Fibroblasts

Many cancer types, including pancreatic cancer, have a dense fibrotic stroma that plays an important role in tumor progression and invasion. Activated cancer associated fibroblasts are a key component of the tumor stroma that interact with cancer cells and support their growth and survival. Models that recapitulate the interaction of cancer cells and activated fibroblasts are important tools for studying the stromal biology and for development of antitumor agents. Here, a method is described for the rapid generation of robust 3-dimensional (3D) spheroid co-culture of pancreatic cancer cells and activated pancreatic fibroblasts that can be used for subsequent biological studies. Additionally, described is the use of 3D spheroids in carrying out functional metabolic assays to probe cellular bioenergetics pathways using an extracellular flux analyzer paired with a spheroid microplate. Pancreatic cancer cells (Patu8902) and activated pancreatic fibroblast cells (PS1) were co-cultured and magnetized using a biocompatible nanoparticle assembly. Magnetized cells were rapidly bioprinted using magnetic drives in a 96 well format, in growth media to generate spheroids with a diameter ranging between 400-600 &#181;m within 5-7 days of culture. Functional metabolic assays using Patu8902-PS1 spheroids were then carried out using the extracellular flux technology to probe cellular energetic pathways. The method herein is simple, allows consistent generation of cancer cell-fibroblast spheroid co-cultures and can be potentially adapted to other cancer cell types upon optimization of the current described methodology.

Here, a method is described for the preparation of 3-dimensional (3D) spheroid co-culture of pancreatic cancer cells and fibroblasts, followed by measurement of metabolic functions using an extracellular flux analyzer.

Many cancer types, including pancreatic cancer, have a dense fibrotic stroma that plays an important role in tumor progression and invasion. Activated ...

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. ...

Fully Human Tumor-based Matrix in Three-dimensional Spheroid Invasion Assay

Two-dimensional cell culture-based assays are commonly used in in vitro cancer research. However, they lack several basic elements that form the tumor microenvironment. To obtain more reliable in vitro results, several three-dimensional (3D) cell culture assays have been introduced. These assays allow cancer cells to interact with the extracellular matrix. This interaction affects cell behavior, such as proliferation and invasion, as well as cell morphology. Additionally, this interaction could induce or suppress the expression of several pro- and anti-tumorigenic molecules. Spheroid invasion assay was developed to provide a suitable 3D in vitro method to study cancer cell invasion. Currently, animal-derived matrices, such as mouse sarcoma-derived matrix (MSDM) and rat tail type I collagen, are mainly used in the spheroid invasion assays. Taking into consideration the differences between the human tumor microenvironment and animal-derived matrices, a human myoma-derived matrix (HMDM) was developed from benign uterus leiomyoma tissue. It has been shown that HMDM induces migration and invasion of carcinoma cells better than MSDM. This protocol provided a simple, reproducible, and reliable 3D human tumor-based spheroid invasion assay using the HMDM/fibrin matrix. It also includes detailed instructions on imaging and analysis. The spheroids grow in a U-shaped ultra-low attachment plate within the HMDM/fibrin matrix and invade through it. The invasion is daily imaged, measured, and analyzed using ilastik and Fiji ImageJ software. The assay platform was demonstrated using human laryngeal primary and metastatic squamous cell carcinoma cell lines. However, the protocol is suitable also for other solid cancer cell lines.

Tumor microenvironment is an essential part of cancer growth and invasion. To mimic carcinoma progression, a biologically relevant human matrix is needed. This protocol introduces an improvement for the in vitro three-dimensional spheroid invasion assay by applying a human leiomyoma-based matrix. The protocol also introduces a computer-based cell invasion analysis.

Two-dimensional cell culture-based assays are commonly used in in vitro cancer research. However, they lack several basic elements that form the tumor ...

Assessing Cell Viability and Death in 3D Spheroid Cultures of Cancer Cells

Three-dimensional spheroids of cancer cells are important tools for both cancer drug screens and for gaining mechanistic insight into cancer cell biology. The power of this preparation lies in its ability to mimic many aspects of the in vivo conditions of tumors while being fast, cheap, and versatile enough to allow relatively high-throughput screening. The spheroid culture conditions can recapitulate the physico-chemical gradients in a tumor, including the increasing extracellular acidity, increased lactate, and decreasing glucose and oxygen availability, from the spheroid periphery to its core. Also, the mechanical properties and cell-cell interactions of in vivo tumors are in part mimicked by this model. The specific properties and consequently the optimal growth conditions, of 3D spheroids, differ widely between different types of cancer cells. Furthermore, the assessment of cell viability and death in 3D spheroids requires methods that differ in part from those employed for 2D cultures. Here we describe several protocols for preparing 3D spheroids of cancer cells, and for using such cultures to assess cell viability and death in the context of evaluating the efficacy of anticancer drugs.

Here, we present several simple methods for evaluating viability and death in 3D cancer cell spheroids, which mimic the physico-chemical gradients of in vivo tumors much better than the 2D culture. The spheroid model, therefore, allows evaluation of the cancer drug efficacy with improved translation to in vivo conditions.

Three-dimensional spheroids of cancer cells are important tools for both cancer drug screens and for gaining mechanistic insight into cancer cell biology. ...

Isolation of Stem-like Cells from 3-Dimensional Spheroid Cultures

Despite advances in adult stem cell research, identification and isolation of stem cells from tissue specimens remains a major challenge. While resident stem cells are relatively quiescent with niche restraints in adult tissues, they enter the cell cycle in anchor-free three-dimensional (3D) culture and undergo both symmetric and asymmetric cell division, giving rise to both stem and progenitor cells. The latter proliferate rapidly and are the major cell population at various stages of lineage commitment, forming heterogeneous spheroids. Using primary normal human prostate epithelial cells (HPrEC), a spheroid-based, label-retention assay was developed that permits the identification and functional isolation of the spheroid-initiating stem cells at a single cell resolution.
HPrEC or cell lines are two-dimensionally (2D) cultured with BrdU for 10 days to permit its incorporation into the DNA of all dividing cells, including self-renewing stem cells. Wash out commences upon transfer to the 3D culture for 5 days, during which stem cells self-renew through asymmetric division and initiate spheroid formation. While relatively quiescent daughter stem cells retain BrdU-labeled parental DNA, the daughter progenitors rapidly proliferate, losing the BrdU label. BrdU can be substituted with CFSE or Far Red pro-dyes, which permit live stem cell isolation by FACS. Stem cell characteristics are confirmed by in vitro spheroid formation, in vivo tissue regeneration assays, and by documenting their symmetric/asymmetric cell divisions. The isolated label-retaining stem cells can be rigorously interrogated by downstream molecular and biologic studies, including RNA-seq, ChIP-seq, single cell capture, metabolic activity, proteome profiling, immunocytochemistry, organoid formation, and in vivo tissue regeneration. Importantly, this marker-free functional stem cell isolation approach identifies stem-like cells from fresh cancer specimens and cancer cell lines from multiple organs, suggesting wide applicability. It can be used to identify cancer stem-like cell biomarkers, screen pharmaceuticals targeting cancer stem-like cells, and discover novel therapeutic targets in cancers.

Using human primary prostate epithelial cells, we report a novel biomarker-free method of functional characterization of stem-like cells by a spheroid-based label-retention assay. A step-by-step protocol is described for BrdU, CFSE, or Far Red 2D cell labeling; three-dimensional spheroid formation; label-retaining stem-like cell identification by immunocytochemistry; and isolation by FACS.

Despite advances in adult stem cell research, identification and isolation of stem cells from tissue specimens remains a major challenge. While resident ...

Detection of Cell-Free DNA in Blood Plasma Samples of Cancer Patients

Identifying mutations in tumors of cancer patients is a very important step in disease management. These mutations serve as biomarkers for tumor diagnosis as well as for the treatment selection and its response in cancer patients. The current gold standard method for detecting tumor mutations involves a genetic test of tumor DNA by means of tumor biopsies. However, this invasive method is difficult to be performed repeatedly as a follow-up test of the tumor mutational repertoire. Liquid biopsy is a new and emerging technique for detecting tumor mutations as an easy-to-use and non-invasive biopsy approach.
Cancer cells multiply rapidly. In parallel, numerous cancer cells undergo apoptosis. Debris from these cells are released into a patient&#8217;s circulatory system, together with finely fragmented DNA pieces, called cell-free DNA (cfDNA) fragments, which carry tumor DNA mutations. Therefore, for identifying cfDNA based biomarkers using liquid biopsy technique, blood samples are collected from the cancer patients, followed by the separation of plasma and buffy coat. Next, plasma is processed for the isolation of cfDNA, and the respective buffy coat is processed for the isolation of a patient&#39;s genomic DNA. Both nucleic acid samples are then checked for their quantity and quality; and analyzed for mutations using next-generation sequencing (NGS) techniques.
In this manuscript, we present a detailed protocol for liquid biopsy, including blood collection, plasma, and buffy coat separation, cfDNA and germline DNA extraction, quantification of cfDNA or germline DNA, and cfDNA fragment enrichment analysis.

In this paper we present a detailed protocol for non-invasive liquid biopsy technique, including blood collection, plasma and buffy coat separation, cfDNA and germline DNA extraction, quantification of cfDNA or germline DNA, and cfDNA fragment enrichment analysis.

Identifying mutations in tumors of cancer patients is a very important step in disease management. These mutations serve as biomarkers for tumor diagnosis ...

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.

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 ...

Three-Dimensional In Vitro Biomimetic Model of Neuroblastoma Using Collagen-Based Scaffolds

Neuroblastoma is the most common extracranial solid tumor in children, accounting for 15% of overall pediatric cancer deaths. The native tumor tissue is a complex three-dimensional (3D) microenvironment involving layers of cancerous and non-cancerous cells surrounded by an extracellular matrix (ECM). The ECM provides physical and biological support and contributes to disease progression, patient prognosis, and therapeutic response.
This paper describes a protocol for assembling a 3D scaffold-based system to mimic the neuroblastoma microenvironment using neuroblastoma cell lines and collagen-based scaffolds. The scaffolds are supplemented with either nanohydroxyapatite (nHA) or glycosaminoglycans (GAGs), naturally found at high concentrations in the bone and bone marrow, the most common metastatic sites of neuroblastoma. The 3D porous structure of these scaffolds allows neuroblastoma cell attachment, proliferation and migration, and the formation of cell clusters. In this 3D matrix, the cell response to therapeutics is more reflective of the in vivo situation.
The scaffold-based culture system can maintain higher cell densities than conventional two-dimensional (2D) cell culture. Therefore, optimization protocols for initial seeding cell numbers are dependent on the desired experimental timeframes. The model is monitored by assessing cell growth via DNA quantification, cell viability via metabolic assays, and cell distribution within the scaffolds via histological staining.
This model&#39;s applications include the assessment of gene and protein expression profiles as well as cytotoxicity testing using conventional drugs and miRNAs. The 3D culture system allows for the precise manipulation of cell and ECM components, creating an environment more physiologically similar to native tumor tissue. Therefore, this 3D in vitro model will advance the understanding of the disease pathogenesis and improve the correlation between results obtained in vitro, in vivo in&#160;animal models, and human subjects.

Three-Dimensional In Vitro Biomimetic Model of Neuroblastoma Using Collagen-Based Scaffolds

This paper lists the steps required to seed neuroblastoma cell lines on previously described three-dimensional collagen-based scaffolds, maintain cell growth for a predetermined timeframe, and retrieve scaffolds for several cell growth and cell behavior analyses and downstream applications, adaptable to satisfy a range of experimental aims.

Neuroblastoma is the most common extracranial solid tumor in children, accounting for 15% of overall pediatric cancer deaths. The native tumor tissue is a ...

A Three-Dimensional Spheroid Model to Investigate the Tumor-Stromal Interaction in Hepatocellular Carcinoma

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver cancer, rationalize its rank as the second most common cause of cancer-related death. Preclinical models need to be adapted to recapitulate the human conditions to select the best therapeutic candidates for clinical development and aid the delivery of personalized medicine. Three-dimensional (3D) cellular spheroid models show promise as an emerging in vitro alternative to two-dimensional (2D) monolayer cultures. Here, we describe a 3D tumor spheroid&#160;model which exploits the ability of individual cells to aggregate when maintained in hanging droplets, and is more representative of an in vivo environment than standard monolayers. Furthermore, 3D spheroids can be produced by combining homotypic or heterotypic cells, more reflective of the cellular heterogeneity in vivo, potentially enabling the study of environmental interactions that can influence progression and treatment responses. The current research optimized the cell density to form 3D homotypic and heterotypic tumor spheroids by immobilizing cell suspensions on the lids of standard 10 cm3 Petri dishes. Longitudinal analysis was performed to generate growth curves for homotypic versus heterotypic tumor/fibroblasts spheroids. Finally, the proliferative impact of fibroblasts (COS7 cells) and liver myofibroblasts (LX2) on homotypic tumor (Hep3B) spheroids was investigated. A seeding density of 3,000 cells (in 20 &#181;L media) successfully yielded Huh7/COS7 heterotypic spheroids, which displayed a steady increase in size up to culture day 8, followed by growth retardation. This finding was corroborated using Hep3B homotypic spheroids cultured in LX2 (human hepatic stellate cell line) conditioned medium (CM). LX2 CM triggered the proliferation of Hep3B spheroids compared to control tumor spheroids. In conclusion, this protocol has shown that 3D tumor spheroids can be used as a simple, economical, and prescreen in vitro tool to study tumor-stromal interactions more comprehensively.

Comprehensive in vitro models that faithfully recapitulate the relevant human disease are lacking. The current study presents three-dimensional (3D) tumor spheroid creation and culture, a reliable in vitro tool to study the tumor-stromal interaction in human hepatocellular carcinoma.

The aggressiveness and lack of well-tolerated and widely effective treatments for advanced hepatocellular carcinoma (HCC), the predominant form of liver ...