title: In-depth characterization of breast cancer tumor-promoting cell transcriptome by RNA sequencing and microarrays.
abstract: Numerous studies have reported the existence of tumor-promoting cells (TPC) with self-renewal potential and a relevant role in drug resistance. However, pathways and modifications involved in the maintenance of such tumor subpopulations are still only partially understood. Sequencing-based approaches offer the opportunity for a detailed study of TPC including their transcriptome modulation. Using microarrays and RNA sequencing approaches, we compared the transcriptional profiles of parental MCF7 breast cancer cells with MCF7-derived TPC (i.e. MCFS). Data were explored using different bioinformatic approaches, and major findings were experimentally validated. The different analytical pipelines (Lifescope and Cufflinks based) yielded similar although not identical results. RNA sequencing data partially overlapped microarray results and displayed a higher dynamic range, although overall the two approaches concordantly predicted pathway modifications. Several biological functions were altered in TPC, ranging from production of inflammatory cytokines (i.e., IL-8 and MCP-1) to proliferation and response to steroid hormones. More than 300 non-coding RNAs were defined as differentially expressed, and 2,471 potential splicing events were identified. A consensus signature of genes up-regulated in TPC was derived and was found to be significantly associated with insensitivity to fulvestrant in a public breast cancer patient dataset. Overall, we obtained a detailed portrait of the transcriptome of a breast cancer TPC line, highlighted the role of non-coding RNAs and differential splicing, and identified a gene signature with a potential as a context-specific biomarker in patients receiving endocrine treatment.
authors.affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Callari
authors.affiliation: Genomnia Srl, Lainate, Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Guffanti
authors.affiliation: Department of Biomedical Sciences, Humanitas University, Rozzano, Milan, Italy.|Humanitas Clinical and Research Center, Rozzano, Milan, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Soldà
authors.affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Merlino
authors.affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Fina
authors.affiliation: Genomnia Srl, Lainate, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Brini
authors.affiliation: Genomnia Srl, Lainate, Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Moles
authors.affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Vera
authors.initials: V
authors.lastname: Cappelletti
authors.affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Daidone
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology; D020869:Gene Expression Profiling / Q000379:methods*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017423:Sequence Analysis, RNA / Q000379:methods*; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics*
chemical_list: D004967:Estrogens; D004958:Estradiol
keywords: breast cancer; cancer stem cells; gene expression; ncRNAs; tumor-promoting cells