Project description:Summary: Melanoma spheroids grown under neural crest cell conditions are highly plastic migratory/invasive tumor cells endowed with immunomodulator function Background: The aggressiveness of melanoma tumors is likely to rely on their well-recognized heterogeneity and plasticity. Melanoma comprises multi subpopulations of cancer cells some of which may possess stem cell-like properties supporting the notion of plasticity. Although useful for certain tumors, the use of the sphere-formation assay to identify stem cell-like or tumor initiating cells subpopulations in human melanoma has been recently challenged. Our study reveals that this assay predicts a functional phenotype associated with aggressive behavior of tumor cells. Methodology/Principal Findings: We analyzed the molecular and functional phenotypes of melanoma spheroids formed in neural crest cell medium. Whether from metastatic (SLM8) or advanced primary (Mela1) tumors, spheroid cells expressed melanoma-associated markers. They displayed higher capacity to differentiate along mesenchymal lineages, and showed enhanced expression of SOX2, NANOG, KLF4, and/or OCT4 transcription factors, but not extensive self-renewal or enhanced tumorigenicity when compared to their adherent counterparts. To determine whether melanoma spheroids in our model could predict a molecular or functional phenotype, we performed gene expression profiling experiments using Affymetrix microarrays. Gene expression profiling attributed a neural crest cell signature to these spheroids and indicated that a migratory/invasive and immune-function modulating program could be associated with these cells. In vitro assays confirmed that these spheroids are endowed with enhanced migratory/invasive capacities. In immune activation assays, spheroid cells elicited a poorer allogenic response from immune cells and inhibited mitogen-dependent T cells activation and proliferation more efficiently than their adherent counterparts. Thus, our findings reveal novel immune-modulator function of melanoma spheroid cells and suggest specific roles for these spheroids in invasion and in evasion of antitumor immunity. Conclusion/Significance: The association of a more plastic, invasive and evasive, thus a more aggressive tumor phenotype with melanoma spheroid cells reveals a previously unrecognized aspect of tumor cells expanded as spheroid cultures. While of limited efficiency for melanoma initiating cell identification, our melanoma spheroid model predicted aggressive phenotype and could therefore, be constructive to investigate melanoma aggressiveness, relevant to patients and clinical transferability. 12 Total samples were analyzed: SLM8 adherent (SLMA) and spheroids (SLMS) cells, and Mela1 adherent (MelaA) and spheroid (MelaS) cells, all performed in triplicates. Paired statistical analyses were performed using Student's paired t-test on the gene signal intensities (gene level) and results were considered statistically significant at p-values <=0.05 and fold-change >=1.5.

Project description:Summary: Melanoma spheroids grown under neural crest cell conditions are highly plastic migratory/invasive tumor cells endowed with immunomodulator function Background: The aggressiveness of melanoma tumors is likely to rely on their well-recognized heterogeneity and plasticity. Melanoma comprises multi subpopulations of cancer cells some of which may possess stem cell-like properties supporting the notion of plasticity. Although useful for certain tumors, the use of the sphere-formation assay to identify stem cell-like or tumor initiating cells subpopulations in human melanoma has been recently challenged. Our study reveals that this assay predicts a functional phenotype associated with aggressive behavior of tumor cells. Methodology/Principal Findings: We analyzed the molecular and functional phenotypes of melanoma spheroids formed in neural crest cell medium. Whether from metastatic (SLM8) or advanced primary (Mela1) tumors, spheroid cells expressed melanoma-associated markers. They displayed higher capacity to differentiate along mesenchymal lineages, and showed enhanced expression of SOX2, NANOG, KLF4, and/or OCT4 transcription factors, but not extensive self-renewal or enhanced tumorigenicity when compared to their adherent counterparts. To determine whether melanoma spheroids in our model could predict a molecular or functional phenotype, we performed gene expression profiling experiments using Affymetrix microarrays. Gene expression profiling attributed a neural crest cell signature to these spheroids and indicated that a migratory/invasive and immune-function modulating program could be associated with these cells. In vitro assays confirmed that these spheroids are endowed with enhanced migratory/invasive capacities. In immune activation assays, spheroid cells elicited a poorer allogenic response from immune cells and inhibited mitogen-dependent T cells activation and proliferation more efficiently than their adherent counterparts. Thus, our findings reveal novel immune-modulator function of melanoma spheroid cells and suggest specific roles for these spheroids in invasion and in evasion of antitumor immunity. Conclusion/Significance: The association of a more plastic, invasive and evasive, thus a more aggressive tumor phenotype with melanoma spheroid cells reveals a previously unrecognized aspect of tumor cells expanded as spheroid cultures. While of limited efficiency for melanoma initiating cell identification, our melanoma spheroid model predicted aggressive phenotype and could therefore, be constructive to investigate melanoma aggressiveness, relevant to patients and clinical transferability.

Project description:Therapeutic screening of potential anticancer agents relies on representative cancer models. In vitro cell culture models have been long questioned to be representative for human malignant glioma. Therefore, in the present study genomic profiles of both short-term (2 weeks; n=8) and long-term (6 and 12 weeks; n=3) primary cell cultures and spheroid cultures were compared with their parental malignant gliomas. Cancer genomic profiles were obtained by 6400 BAC array comparative genomic hybridization. In 7 out of 8 short-term primary cell cultures, the genomic profiles clustered further from their parental tumors than the spheroid cultures. In 4 out of 8 samples, the changes were substantial and included chromosomal regions associated with prognosis and therapeutic response. The average correlation coefficients between parental tumor profiles and spheroid profiles was 0.89 (range: 0.79 to 0.97), whereas those between parental tumors and cell cultures was 0.62 (range: 0.10 to 0.96). In 2 out of 3 primary cell cultures progressive genetic changes appeared at 6 and 12 weeks after initial preservation, whereas the spheroid cultures were genetically stable throughout. It is concluded that the cancer genomic profile of primary cell cultures from malignant glioma is inconsistent with the parental tumorâs profile already after 2 weeks with subsequent progressive genetic changes. Because malignant glioma spheroids are genetically stable, biological characteristics of the parental tumor are better reflected. This indicates that the spheroid model is better for therapeutic screening. Keywords: comparative genomic hybridization Two in vitro culture models (primary cell culture and organotypic spheroid culture) and their parental tumor were compared in whole-genome DNA copy number profile. Malignant glioma surgical specimens from 8 patients were divided in parental tumor (T), primary cell culture (C) and organotypic spheroid culture (S). After 2 weeks, genomic DNA was extracted from culture harvests. For 3 of 8 surgical specimens (patient 55, 58, 60) cultures were extended to 6 and 12 weeks to determine DNA copy number changes in time. Primary cell culture harvests at 2, 6 and 12 weeks were named C1, C2, C3 and organotypic spheroid cultures harvests at 2, 6 and 12 weeks were named S1, S2, S3.

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Characterization of genetic intratumor heterogeneity in colorectal cancer and matching patient-derived spheroid cultures.

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