title: What Do We Learn from Spheroid Culture Systems? Insights from Tumorspheres Derived from Primary Colon Cancer Tissue.
abstract: 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.
authors.affiliation: Molecular Disease Mechanisms Group, Life Sciences Research Unit, University of Luxembourg, 6 Avenue du Swing, L-4367, Campus Belval, Luxembourg.
authors.forename: Komal
authors.initials: K
authors.lastname: Qureshi-Baig
authors.affiliation: Molecular Disease Mechanisms Group, Life Sciences Research Unit, University of Luxembourg, 6 Avenue du Swing, L-4367, Campus Belval, Luxembourg.
authors.forename: Pit
authors.initials: P
authors.lastname: Ullmann
authors.affiliation: Molecular Disease Mechanisms Group, Life Sciences Research Unit, University of Luxembourg, 6 Avenue du Swing, L-4367, Campus Belval, Luxembourg.
authors.forename: Fabien
authors.initials: F
authors.lastname: Rodriguez
authors.affiliation: Integrated Biobank of Luxembourg, 6 rue Nicolas Ernest Barblé, L-1210, Luxembourg, Luxembourg.
authors.forename: Sónia
authors.initials: S
authors.lastname: Frasquilho
authors.affiliation: Luxembourg Institute of Health, Genomics Research Unit, 84 Val Fleuri, L-1526, Luxembourg, Luxembourg.
authors.forename: Petr V
authors.initials: PV
authors.lastname: Nazarov
authors.affiliation: Molecular Disease Mechanisms Group, Life Sciences Research Unit, University of Luxembourg, 6 Avenue du Swing, L-4367, Campus Belval, Luxembourg.
authors.forename: Serge
authors.initials: S
authors.lastname: Haan
authors.affiliation: Molecular Disease Mechanisms Group, Life Sciences Research Unit, University of Luxembourg, 6 Avenue du Swing, L-4367, Campus Belval, Luxembourg.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Letellier
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D003110:Colonic Neoplasms / Q000235:genetics / Q000401:mortality / Q000473:pathology*; D005434:Flow Cytometry; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008856:Microscopy, Fluorescence; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D060888:Real-Time Polymerase Chain Reaction; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism; D018874:Spheroids, Cellular / Q000166:cytology / Q000378:metabolism*; D016019:Survival Analysis; D059467:Transcriptome; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D018398:Homeodomain Proteins; C116884:LGR5 protein, human; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D043562:Receptors, G-Protein-Coupled; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors