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Transcriptional signature of IFN-alfa in the side population of ovarian cancer cells

ABSTRACT: 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. Keywords: response to IFN-alfa

ORGANISM(S): Homo sapiens

PROVIDER: GSE9481 | GEO | 2008/10/29

SECONDARY ACCESSION(S): PRJNA103257

REPOSITORIES: GEO

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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:Interferon (IFN)-alpha causes high rates of depression and fatigue, and is used to investigate the impact of innate immune cytokines on brain and behavior. However, little is known about transcriptional profiles of circulating immune cells during chronic IFN-alpha administration. Accordingly, genome-wide transcriptional profiling was performed on peripheral blood mononuclear cells from 21 patients with chronic hepatitis C virus either awaiting IFN-alpha therapy (n=10) or after 12 weeks of IFN-alpha treatment (n=11). Significance analysis of microarray data identified 252 up-regulated gene transcripts, the majority of which were related to IFN-alpha/antiviral or innate-immune/inflammatory signaling. Of these upregulated genes, 2'-5'-oligoadenylate synthetase 2 (OAS2) was the only gene that was differentially expressed in patients that developed IFN-alpha-induced depression/fatigue, and correlated with depression and fatigue scores at 12 weeks of IFN-alpha administration. Promoter-based bioinformatic and cellular origin analyses revealed IFN-alpha-induced increases in genes bearing transcription factor binding motifs (TFBMs) related to myeloid differentiation, IFN-alpha signaling, API and CREB/ATF family of transcription pathways, with changes derived primarily from monocytes and plasmacytoid dendritic cells. Patients with high depression/fatigue scores demonstrated up-regulation of genes bearing TFBMs for myeloid differentiation, IFN-alpha and AP1 signaling, and down regulation of TFBMs for CREB/ATF-related transcription factors. Cellular origin analyses indicated a shift toward genes derived from CD8+T and NK cells in subjects with high depression/fatigue scores. These results reveal an antiviral and inflammatory transcriptional profile after 12 weeks IFN-alpha, accompanied by increased OAS2 expression, decreased CREB/ATF transcriptional control, and a shift from monocyte-derived genes to those of cytotoxic lymphocytes in IFN-alpha-induced depression/fatigue. Total RNA was isolated from the peripheral blood mononuclear cells (PBMC) obtained at 12 weeks from HCV patients treated with IFN-alpha plus ribavirin (n=11) and untreated HCV patients awaiting IFN-alpha/ribavirin therapy (control subjects, n=10).

Project description:Previously, we have identified the RUNX2 gene as hypomethylated and overexpressed in post-chemotherapy (CT) primary cultures derived from epithelial ovarian cancer (EOC) patients, when compared to primary cultures derived from matched primary (prior to CT) tumors. However, we found no differences in the RUNX2 methylation in primary EOC tumors and EOC omental metastases, suggesting that DNA methylation-based epigenetic mechanisms have no impact on RUNX2 expression in advanced (metastatic) stage of the disease. Moreover, RUNX2 displayed significantly higher expression not only in metastatic tissue, but also in high-grade primary tumors and even in low malignant potential tumors. Knockdown of the RUNX2 expression in EOC cells led to sharp decrease of cell proliferation and significantly inhibited EOC cell migration and invasion. Gene expression profiling and consecutive network and pathway analyses confirmed these findings, as various genes and pathways known previously to be implicated in ovarian tumorigenesis, including EOC tumor invasion and metastasis, were found to be downregulated upon RUNX2 suppression, while a number of pro-apoptotic genes and some EOC tumor suppressor genes were induced. Taken together, our data are indicative for a strong oncogenic potential of the RUNX2 gene in EOC progression and suggest that RUNX2 might be a novel EOC therapeutic target. Further studies are needed to more completely elucidate the functional implications of RUNX2 and other members of the RUNX gene family in ovarian tumorigenesis. To better understand the molecular mechanisms of RUNX2 gene action in ovarian cancer cells, we employed the Agilent Whole Human Genome microarrays, containing ~ 44,000 genes to identify global gene expression changes upon RUNX2 suppression in SKOV3 cells. We compared the gene expression of the previously selected clone shRNA- RUNX2-knockdown clone 3 (cl3) against the corresponding control clone. The microarray experiments were performed in duplicates, as two hybridizations were carried out for the RUNX2-suppressing cell clone against the corresponding control, using a fluorescent dye reversal (dye-swap) technique.

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Transcriptional signature of IFN-alfa in the side population of ovarian cancer cells

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