Unknown,Transcriptomics,Genomics,Proteomics

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Genotypic and phenotypic characterization of the side population of gastric cancer cell lines

ABSTRACT: To sum up our results, we managed to isolate a reproducible SP cell fraction of human gastric carcinoma cell lines for the first time. Those cells differed from the rest of the population regarding morphology and biological behaviour. They had the ability to build a population resembling the basic tumor population and therefore performed differenziation and asymmetric cell division. SP cells expressed potential stem cell markers like musashi 1 and Cd133 and also showed a high expression of genes that encode for stem cell properties. The so identified phenotypic and genetic factors showed a variable expression in tumor samples of patient series and might be applicable as prognostic factors in the diagnosis of gastric carcinoma. Aims: The side population (SP) of tumor cell lines shares characteristics with tumor stem cells. In this study we phenotypically and genotypically characterized the SP of gastric cancer cell lines. Methods: The SP was obtained from MKN45- and AGS-gastric cancer cells using Hoechst 33342 staining and fluorescence-activated cell sorting (FACS). SP cells were subsequently studied morphologically (cytology, immunocytochemistry), on the transcriptional level (gene array) and in cell culture (recultivation assays). Genes differentially expressed in the SP cells were finally searched by immunohistochemistry in neoplastic and non-neoplastic gastric tissue from gastric cancer patients. Results: The SP was reproducibly obtained from gastric cancer cell lines. The SP cells were smaller and rounder then non-SP cells. SP cells self-renewed in re-cultivation experiments and differentiated into SP- and non-SP cells. Re-cultivated SP- and non-SP cells showed distinct phenotypes in culture regarding cell shape and colony-formation. SP cells had increased levels of the stem cell markers CD133 and Musashi 1. Transcriptional analyses demonstrated that SP cells express genes that encode for stem cell properties like FZD7, HEY1, SMO and ADAM17. Finally we detected the transcripts of these genes in tissue samples from patients with gastric cancer. Conclusions: Human gastric cancer cell lines enclose a phenotypically and genotypically distinct cell population with tumor stem cell features. Phenotypical characteristics of this distinct cell population are also present in gastric cancer tissue.

ORGANISM(S): Homo sapiens

SUBMITTER: Rosa Schmuck

PROVIDER: E-GEOD-20058 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The recent identification of cancer stem cells (CSCs) in multiple human cancers provides a new inroad to understanding tumorigenesis at the cellular level. CSCs are defined by their characteristics of self-renewal, multipotentiality, and tumor initiation upon transplantation. By testing for these defining characteristics, we provide evidence for the existence of CSCs in a transgenic mouse model of glioma, S100Ã-verbB;Trp53. In this glioma model, CSCs are enriched in the side-population (SP) cells. These SP cells have enhanced tumor-initiating capacity, self-renewal, and multipotentiality compared to non-SP cells from the same tumors. Furthermore, gene expression analysis comparing FACS-sorted cancer SP cells to non-SP cancer cells and normal neural SP cells identified 45 candidate genes that are differentially expressed in glioma stem cells. We validated the expression of two genes from this list (S100a4 and S100a6) in primary mouse gliomas and human glioma samples. Analyses of xenografted human GBM (glioblatoma multiforme) cell lines and primary human glioma tissues show that S100A4 and S100A6 are expressed in a small subset of cancer cells and that their abundance is positively correlated to tumor grade. In conclusion, this study shows that CSCs exist in a mouse glioma model, suggesting that this model can be used to study the molecular and cellular characteristics of CSCs in vivo and to further test the cancer stem cell hypothesis. Experiment Overall Design: This study features two factors, injected cell origin (either tumorsphere or neurosphere) and FACS cell population (either side population or non-side population cells). There were two different tumorspheres, labeled 3447 and 4346 that were isolated from brain tumors in S100beta-verbB;p53-/- or S100beta-verbB;p53+/- mice. The tumorspheres were injected separately into the brains of NOD.Cg-Prkdc<scid>Il2rg<tm1Wjl>/SzJ mice to generate biological triplicates of each primary tumor. Tumorspheres were isolated and cultured before FACS sorting to obtain side population and non-side population cells. As a control, untransformed neurospheres from three independent S100beta-verbB;p53-/- or S100beta-verbB;p53+/- mice were isolated, cultured, and FACS sorted to obtain side population and non-side population cells. Side population and non-side population cells cultured from three mice injected with the 3447 cultured tumorspheres were assayed for gene expression (six samples). Side-population stem cells cultured from three mice injected with the 4346 cultured tumorspheres were assayed for gene expression (three samples). Side-population and non-side population cells cultured from three mice injected with the neurospheres were assayed for gene expression (six samples).

Project description:The side population (SP), recently identified in several normal tissues and in a variety of tumors, may comprise cells endowed with stem cell features. In this study, we investigated the presence of SP in epithelial ovarian cancer (EOC) and found it in 4 out of 6 primary cultures from xenotransplants, as well as in 9 out of 25 clinical samples analyzed. SP cells from one xenograft bearing a large SP fraction were characterized in detail and they were capable of recreate the full repertoire of cancer cell populations observed in the parent tumor. Moreover, SP cells had higher proliferation rates, were much less apoptotic compared to non-SP cells, and generated tumors more rapidly than non-SP cells. We also investigated the effects of interferon-alfa (IFN-alpha), a cytokine which has been widely used to treat solid tumors, on EOC cells and observed that IFN-alpha exerts marked anti-proliferative and pro-apoptotic effects on primary cultures containing SP cells. IFN-alfa-treatment invariably caused a dramatic reduction in SP size in tumor cell lines of different origin and in normal bone-marrow SP cells, associated with a distinctive transcriptional profile. Gene therapy with human IFN-alpha resulted in regression of established tumors bearing a large SP fraction, which was not observed when tumors bearing low SP levels were treated. These findings could have relevant clinical implications since they imply that tumors bearing large SP numbers - albeit rare - could be sensitive to IFN-alpha treatment. Experiment Overall Design: 4 Affymetrix microarrays: Experiment Overall Design: 2 technical replicates: Ovarian cancer, untreated Side Population, rep1 Experiment Overall Design: Ovarian cancer, untreated Side Population, rep2 Experiment Overall Design: + Experiment Overall Design: 2 technical replicates: Ovarian cancer, IFN-alpha treated Side Population, rep1 Experiment Overall Design: Ovarian cancer, IFN-alpha treated Side Population, rep2

Project description:Novel therapies targeting cancer stem cells (CSCs), which play critical roles in chemo- and radio-resistance, metastasis, and possibly resistance against cancer immunotherapy including granulocyte-macrophage colony-stimulating factor (GM-CSF) gene-transduced tumor cell vaccines, may provide beneficial clinical outcomes. Here, we used syngeneic immunocompetent mice that allowed precise evaluation of the immunogenicity of the side population (SP) isolated from 4T1 murine breast carcinoma (4T1-SP) cells as putative CSCs. 4T1-SP cells showed various stem cell properties including high capacities for colony formation and tumorigenicity as well as high expression of phosphorylated signal transducer and activator of transcription-3 and vascular endothelial growth factor that are inductive of immune tolerance. Despite these progressive malignant characteristics of 4T1-SP cells, subcutaneous injection of non-transmissible Sendai virus-mediated GM-CSF gene-transduced 4T1-SP (4T1-SP/GM) cells remarkably impaired their tumorigenicity compared with that of the controls. This impairment of tumorigenicity was partially dependent on CD8+ T cells in concert with CD4+ T cells and natural killer cells. Notably, therapeutic vaccinations using irradiated 4T1-SP/GM cells markedly suppressed tumor development of subcutaneously transplanted 4T1-SP cells compared with that of the controls including irradiated 4T1-non-SP/GM cells. Tumor suppression was accompanied by robust accumulation of mature dendritic cells at vaccination sites and systemic Th1-based cellular immunity. Moreover, vaccinations comprising primary 4T1-SP cells isolated from transplanted 4T1-SP tumors elicited antitumor effects. cDNA microarray analysis showed that 4T1-SP cells predominantly expressed genes of cancer-related antigens including cancer/testis antigens. Collectively, we demonstrate that SP cell-based vaccinations induce effective antitumor immunity that may improve the efficacy of SP cell-based immunotherapy. Gene expression profiles were compared between sorted 4T1-SP and 4T1-NSP cells.

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Genotypic and phenotypic characterization of the side population of gastric cancer cell lines

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