What Do We Learn from Spheroid Culture Systems? Insights from Tumorspheres Derived from Primary Colon Cancer Tissue

• Published in: PloS one Vol. 11; no. 1; p. e0146052
• Main Authors: Qureshi-Baig, Komal, Ullmann, Pit, Rodriguez, Fabien, Frasquilho, Sónia, Nazarov, Petr V., Haan, Serge, Letellier, Elisabeth
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08.01.2016; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Biology and Life Sciences; Cancer; Cancer therapies; Cell culture; Cell Culture Techniques; Cell Differentiation; Cell self-renewal; Chemoresistance; Chemotherapy; Colon; Colon cancer; Colonic Neoplasms - genetics; Colonic Neoplasms - mortality; Colonic Neoplasms - pathology; Colorectal cancer; Colorectal carcinoma; Comparative analysis; Drug resistance; Esophagus; Floating; Flow Cytometry; Gene expression; Genetic aspects; Growth factors; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Humans; Internet; Kinases; Life sciences; Medicine and Health Sciences; Mice; Mice, Inbred NOD; Mice, SCID; Microscopy, Fluorescence; Mutation; Nanog Homeobox Protein; Oct-4 protein; Octamer Transcription Factor-3 - genetics; Octamer Transcription Factor-3 - metabolism; Oligonucleotide Array Sequence Analysis; Plastics; Proteins; Real-Time Polymerase Chain Reaction; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - metabolism; Research and analysis methods; Risk factors; Serum-free medium; SOXB1 Transcription Factors - genetics; SOXB1 Transcription Factors - metabolism; Spheroids, Cellular - cytology; Spheroids, Cellular - metabolism; Stem cells; Studies; Survival Analysis; Transcriptome; Transplantation, Heterologous; Tumor Cells, Cultured; Tumors; United States; Luxembourg
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0146052

Due to their self-renewal and tumorigenic properties, tumor-initiating cells (TICs) have been hypothesized to be important targets for colorectal cancer (CRC). However the study of TICs is hampered by the fact that the identification and culturing of TICs is still a subject of extensive debate. Floating three-dimensional spheroid cultures (SC) that grow in serum-free medium supplemented with growth factors are supposed to be enriched in TICs. We generated SC from fresh clinical tumor specimens and compared them to SC isolated from CRC cell-lines as well as to adherent differentiated counterparts. Patient-derived SC display self-renewal capacity and can induce serial transplantable tumors in immuno-deficient mice, which phenotypically resemble the tumor of origin. In addition, the original tumor tissue and established SC retain several similar CRC-relevant mutations. Primary SC express key stemness proteins such as SOX2, OCT4, NANOG and LGR5 and importantly show increased chemoresistance ability compared to their adherent differentiated counterparts and to cell line-derived SC. Strikingly, cells derived from spheroid or adherent differentiating culture conditions displayed similar self-renewal capacity and equally formed tumors in immune-deficient mice, suggesting that self-renewal and tumor-initiation capacity of TICs is not restricted to phenotypically immature spheroid cells, which we describe to be highly plastic and able to reacquire stem-cell traits even after long differentiation processes. Finally, we identified two genes among a sphere gene expression signature that predict disease relapse in CRC patients. Here we propose that SC derived from fresh patient tumor tissue present interesting phenotypic features that may have clinical relevance for chemoresistance and disease relapse and therefore represent a valuable tool to test for new CRC-therapies that overcome drug resistance.