Alternative splicing profiling of human breast cancer cell lines
Ontology highlight
ABSTRACT: We assessed alternative splicing in breast cancer through global profiling of transcriptomes of basal and luminal subtype cell lines using Affymetrix Human Junction Array.
Project description:CDC25 (cell division cycle 25) phosphatases are essential for cell cycle control under normal conditions and in response to DNA damage. They are represented by three isoforms, CDC25A, B and C, each of them being submitted to an alternative splicing mechanism. Alternative splicing of many genes is affected in response to genotoxic stress, but the impact of such a stress on CDC25 splicing has never been investigated. In this study, we demonstrate that genotoxic agents (doxorubicin, camptothecin, etoposide and cisplatin), alter the balance between CDC25C splice variants in human breast cancer cell lines both at the mRNA and protein levels. This modulation occurs during the response to moderate, sub-lethal DNA damage. Our results also suggest that the CDC25C splice variants expression shift induced by a genotoxic stress is dependent on the ATM/ATR signaling but not on p53. This study highlights the modulation of CDC25C alternative splicing as an additional regulatory event involved in cellular response to DNA damage in breast cancer cells.
Project description:We assessed alternative splicing in breast cancer through global profiling of transcriptomes of basal and luminal subtype cell lines using Affymetrix Human Junction Array.
Project description:Total RNA from 46 breast cell lines was labelled using the Illumina TotalPrep RNA Amplification kit (Ambion) following manufacturer's instructions. 1.5 µg of biotin-labelled cRNA were used for each hybridisation on Sentrix Human-6 v1 BeadChips (Illumina, San Diego, CA) following manufacturer's protocol.
Project description:In an experimental model of tumor dormancy, heat shock protein 27 (HSP27) was up-regulated in angiogenic human breast cancer cells when compared with non-angiogenic cells. Stable down-regulation of HSP27 in angiogenic tumor cells was followed by long-term tumor dormancy in vivo and associated with reduced intra-tumoral endothelial cell proliferation, decreased secretion of VEGF and bFGF from tumor cells, and increased expression of thrombospondin-1. Phosphorylation of the transcription factor STAT3 and nuclear expression of NFκB were reduced following suppression of HSP27. In contrast, tumor cell proliferation and apoptosis were not affected. By clinical validation, high HSP27 expression was associated with markers of aggressive tumors and decreased survival in breast cancer and melanoma patients. Our present findings suggest a link between HSP27 and dormancy through tumor-vascular interactions. Targeting HSP27, a multifunctional cytoprotective protein, might offer a novel strategy in cancer treatment.
Project description:Transcriptional profiling was conducted on RNA from 23 breast cancer cell lines to identify genes whose expression level correlates with sensitivity of particular drug Experiment Overall Design: Baseline gene expression profiling was performed using 23 breast cancer cell lines to identify genomic signatures highly correlated with in vitro sensitivity to a particular drug
Project description:Transposable elements (TEs) drive genome evolution and can affect gene expression through diverse mechanisms. In breast cancer, disrupted regulation of TE sequences may facilitate tumor-specific transcriptomic alterations. We examine 142,514 full-length isoforms derived from long-read RNA sequencing (LR-seq) of 30 breast samples to investigate the effects of TEs on the breast cancer transcriptome. Approximately half of these isoforms contain TE sequences, and these contribute to half of the novel annotated splice junctions. We quantify splicing of these LR-seq derived isoforms in 1,135 breast tumors from The Cancer Genome Atlas (TCGA) and 1,329 healthy tissue samples from the Genotype-Tissue Expression (GTEx), and find 300 TE-overlapping tumor-specific splicing events. Some splicing events are enriched in specific breast cancer subtypes - for example, a TE-driven transcription start site upstream of ERBB2 in HER2+ tumors, and several TE-mediated splicing events are associated with patient survival and poor prognosis. The full-length sequences we capture with LR-seq reveal thousands of isoforms with signatures of RNA editing, including a novel isoform belonging to RHOA; a gene previously implicated in tumor progression. We utilize our full-length isoforms to discover polymorphic TE insertions that alter splicing and validate one of these events in breast cancer cell lines. Together, our results demonstrate the widespread effects of dysregulated TEs on breast cancer transcriptomes and highlight the advantages of long-read isoform sequencing for understanding TE biology. TE-derived isoforms may alter the expression of genes important in cancer and can potentially be used as novel, disease-specific therapeutic targets or biomarkers.