LINC00520 is Induced by Src, STAT3, and PI3K and Plays a Functional Role in Breast Cancer
ABSTRACT: Long non-coding RNAs (lncRNAs) have been implicated in normal cellular homeostasis as well as pathophysiological conditions, including cancer. Here we performed global gene expression profiling of mammary epithelial cells transformed by oncogenic v-Src, and identified a large subset of uncharacterized lncRNAs potentially involved in breast cancer development. Specifically, our analysis revealed a novel lncRNA, LINC00520 that is upregulated upon ectopic expression of oncogenic v-Src, in a manner that is dependent on the transcription factor STAT3. Similarly, LINC00520 is also increased in mammary epithelial cells transformed by oncogenic PI3K and its expression is decreased upon knockdown of mutant PIK3CA. Additional expression profiling highlight that LINC00520 is elevated in a subset of human breast carcinomas, with preferential enrichment in the basal-like molecular subtype. ShRNA-mediated depletion of LINC00520 results in decreased cell migration and loss of invasive structures in 3D. RNA sequencing analysis uncovers several genes that are differentially expressed upon ectopic expression of LINC00520, a significant subset of which are also induced in v-Src-transformed MCF10A cells. Together, these findings characterize LINC00520 as a lncRNA that is regulated by oncogenic Src, PIK3CA and STAT3, and which may contribute to the molecular etiology of breast cancer. Overall design: Transcriptome profiling of MCF10A-Src transformation and LINC00520 over expression
Project description:siSTAT3 knockdown of a tamoxifen initiated, transformation inducible, breast cancer model system (MCF10A-ER-Src), with associated controls of EtOH and siNEG treatments. A description of MCF10A-ER-Src cells can be found here: www.encodeproject.org Overall design: In order to determine the contribution of STAT3 to the gene expression profile of cells undergoing transformation, STAT3 was depleted prior to transformation.
Project description:Mutant PIK3CA and Her2 genes are oncogenic and their co-existence in breast cancer has been well identified. However, the gene targets and cell signalling pathway regulated by mutant PIK3CA, Her2 and both of PIK3CA and Her2 have not been well studied. We established stable cell models through transfecting mutant PIK3CA, Her2 and both mutant PIK3CA and Her2 into MCF10A cells and performed Affymetrix microarray to identify downstream target genes controlled by either mutant PIK3CA, Her2 or both PIK3CA and Her2. Overall design: RNA was extracted from 4 cell models (MCF10A/LacZ, MCF10A/Her2, MCF10A/mutant PIK3CA, and MCF10A/Her2+mutant PIK3CA) and purified using the RNeasy plus miniKit. Affymetrix microarray was performed and downstream target genes controlled by either mutant PIK3CA, Her2 or both PIK3CA and Her2 were identified. We also analyzed the cell signaling pathways enrichment.
Project description:Using an inducible, inflammatory model of breast cellular transformation, we describe the transcriptional regulatory network mediated by STAT3, NF-kB, and AP-1 factors on a genomic scale. These regulators form transcriptional complexes that directly regulate the expression of hundreds of genes in oncogenic pathways, such as cell proliferation, metastasis, angiogenesis, apoptosis and metabolism, via a positive feedback loop. This inflammatory feedback loop and associated network, which function to various extents in many types of cancer cells and patient tumors, is the basis for an “inflammation” index that defines cancer types by functional criteria. The inflammation index is negatively correlated with expression of genes involved in DNA metabolism, and transformation is associated with genome instability. Inflammatory tumors are preferentially associated with infiltration immune cells that might be recruited to the site of the tumor via inflammatory molecules produced by the cancer cells. Overall design: ChIP-seq for STAT3, NF-kb, JUN, JUNB and FOS before and after MCF10A-ER-Src cell transformation
Project description:Using an inducible, inflammatory model of breast cellular transformation, we describe the transcriptional regulatory network mediated by STAT3, NF-kB, and AP-1 factors on a genomic scale. These regulators form transcriptional complexes that directly regulate the expression of hundreds of genes in oncogenic pathways, such as cell proliferation, metastasis, angiogenesis, apoptosis and metabolism, via a positive feedback loop. This inflammatory feedback loop and associated network, which function to various extents in many types of cancer cells and patient tumors, is the basis for an “inflammation” index that defines cancer types by functional criteria. The inflammation index is negatively correlated with expression of genes involved in DNA metabolism, and transformation is associated with genome instability. Inflammatory tumors are preferentially associated with infiltration immune cells that might be recruited to the site of the tumor via inflammatory molecules produced by the cancer cells. Overall design: RNA-seq during MCF10A-ER-Src cell transformation and after STAT3, NF-kb, JUN, JUNB and FOS knockouts
Project description:We applied ribosome profiling and RNA sequencing to examine gene expression regulation during oncogenic cell transformation. One model involves normal mammary epithelial cells (MCF10A) containing ER-Src. Treatment of such cells with tamoxifen rapidly induces Src, thereby making it possible to kinetically follow the transition between normal and transformed cells. The other model consists of three isogenic cell lines derived from primary fibroblasts in a serial manner (Hahn et al., 1999). EH cell is immortalized by overexpression of telomerase (hTERT), and exhibits normal fibroblast morphology. EL cell expresses hTERT along with both large and small T antigens of Simian virus 40, and it displays an altered morphology but is not transformed. ELR cell expresses hTERT, T antigens, and an oncogenic derivative of Ras (H-RasV12). Overall design: Ribosome profiling and RNA sequencing in two cancer cell models
Project description:We have performed a comprehensive analysis of how oncogenic transformation induced by v-Src kinase remodels the proteomic landscape of human breast epithelial (MCF10A) cells. We characterised the proteome of untransformed cells to a depth of ~14,000 proteins, spanning a wide dynamic range of expression levels. Changes in both protein abundance and protein turnover were analysed, in biological triplicate, at seven time points spanning 1-72 hours post v-Src activation, coincident with profound phenotypic changes in cell behaviour and morphology. These data are provided for interactive exploration via the Encyclopedia of Proteome Dynamics database (www.peptracker.com/epd). We detect only a small subset (<3%) of mostly low copy number proteins showing altered abundance and/or half-life after transformation, including proteins regulated at the post-transcriptional level. Src activation modulated proteins with diverse cellular functions and with differential response kinetics. The resulting ‘Src signature’ is shown to be prognostic of reduced cancer patient survival post diagnosis.
Project description:We performed RNA-seq to examine RNA expression profiles during MCF10A-ER-Src cell transformation and upon knockdowns of transcription factors Overall design: RNA-seq before and after MCF10A-ER-Src cell transformation, and RNA-seq upon factor knockdowns after inducing cell transformation
Project description:Basal-like and triple negative breast cancer (TNBC) share common molecular features, poor prognosis and a propensity for metastasis to the brain. Amplification of EGFR occurs in ~50% of basal-like breast cancer and mutations in the epidermal growth factor receptor (EGFR) have been reported in up to ~ 10% of Asian TNBC patients. In non-small cell lung cancer several different mutations in the EGFR tyrosine kinase domain confer sensitivity to receptor tyrosine kinase inhibitors, but the tumourigenic potential of EGFR mutations in breast cells and their potential for targeted therapy is unknown. Constructs containing wild type, G719S or E746-A750 deletion mutant forms of EGFR were transfected into the ‘near normal’ MCF10A breast cells and their tumorigenic derivative, MCF10CA1a. These transfected lines were used to investigate the effects of EGFR over-expression and mutation on proliferation, migration, invasion, response to gefitinib, and tumour formation in vivo. We also carried out copy number analysis and whole exome sequencing of the MCF10A and MCF10CA1a cell lines. Both activating mutations of EGFR increased the proliferative ability of MCF10A and MCF10CA1a cell lines, and increased the anchorage-independent growth and sensitivity to gefitinib in MCF10A cells. In addition, the EGFR-E746-A750 deletion increased the migratory and invasive abilities of the MCF10CA1a cell line in vitro, and greatly increased the formation and growth of MCF10CA1a tumours in vivo. Compared to MCF10A cells, MCF10CA1a cells had large regions of gain on chromosome 9 and the long arm of chromosome 3, deletion in the short arm of chromosome 7, and mutations in many genes implicated in cancer. The EGFR E746-A750 deletion mutation, and to a lesser extent G719S, greatly enhance the oncogenic properties of MCF10A cell line, and increase sensitivity to gefitinib. Although the addition of EGFR E746-A750 renders the MCF10CA1a cells more tumourigenic in vivo it is not accompanied by increased sensitivity to gefitinib, perhaps because of additional mutations, including the PIK3CA H1047R mutation, that the MCF10CA1a cell line has acquired. Screening TNBC/basal-like breast cancer for EGFR mutations may prove useful for directing therapy but, as in non-small cell lung cancer cancer, accompanying mutations in PIK3CA may confer gefitinib resistance. Overall design: DNA extracted from MCF10A and MCF10CA1a cell lines were analyzed for copy number differences using Illumina Human Omni 2.5M SNP arrays.
Project description:While growth factor-independent signaling and proliferation are well-established hallmarks of cancer, little is known regarding growth factor-independent changes in gene expression which occur downstream from oncogenes. The PI3K pathway is one of the most commonly misregulated signaling pathways in human cancers. Here, MCF10A cells expressing the two most common PI3K mutations, PIK3CA E545K and H1047R, were used to identify the repertoire of genes altered by oncogenic PI3K mutations following growth factor deprivation. This gene set most closely correlated with gene signatures from claudin-low and basal-like breast tumors, and categorical enrichment analyses suggested that NF-kB target genes were dramatically upregulated by these mutations. An IKKb inhibitor was used to identify the subset of PI3K-driven genes that is NF-kB dependent. Interestingly, virtually all of these NF-kB dependent genes were secreted proteins, suggesting a paracrine role for this gene set. Among these genes was IL-6, a cytokine frequently expressed in tumors which plays a critical role in generating a tumor-promoting microenvironment. Consistent with this, conditioned media from cells expressing the E545K or H1047R mutations led to increased STAT3 activation in recipient THP-1 monocytes or normal epithelial cells in a NF-kB and IL-6-dependent manner. Together, these data describe a PI3K-driven, NF-kB-dependent gene expression profile which may play a critical role in promoting a microenvironment amenable to tumor progression. 39 normal cell lines vs treated cell lines for micorarray analysis
Project description:Breast cancer is the most frequent cancer in women and consists of heterogeneous types of tumours that are classified into different histological and molecular subtypes1-3. Pik3ca and p53 are the two most frequently mutated genes and are associated with different types of human breast cancers4. The cellular origin and the mechanisms leading to Pik3ca-induced tumour heterogeneity remain unknown. Here, we used a genetic approach in mice to define the cellular origin of Pik3ca-derived tumours and its impact on tumour heterogeneity. Surprisingly, oncogenic Pik3ca-H1047R expression at physiological levels5 in basal cells (BCs) using K5CREERT2 induced the formation of luminal ER+PR+ tumours, while its expression in luminal cells (LCs) using K8CREERT2 gave rise to luminal ER+PR+ tumours or basal-like ER-PR- tumours. Concomitant deletion of p53 and expression of Pik3ca-H1047R accelerated tumour development and induced more aggressive mammary tumours. Interestingly, expression of Pik3ca-H1047R in unipotent BCs gave rise to luminal-like cells, while its expression in unipotent LCs gave rise to basal-like cells before progressing into invasive tumours. Transcriptional profiling of cells that have undergone cell fate transition upon Pik3ca-H1047R expression in unipotent progenitors demonstrate a profound oncogene-induced reprogramming of these newly formed cells and identified gene signatures, characteristic of the different cell fate switches that occur upon Pik3ca-H1047R expression in BC and LCs, which correlated with the cell of origin, tumour type and different clinical outcomes. Altogether our study identifies the cellular origin of Pik3ca-induced tumours and reveals that oncogenic Pik3ca-H1047R activates a multipotent genetic program in normally lineage-restricted populations at the early stage of tumour initiation, setting the stage for future intratumoural heterogeneity. These results have important implications for our understanding of the mechanisms controlling tumour heterogeneity and the development of new strategies to block PIK3CA breast cancer initiation. Luminal and basal cells, or tumour cells, from mice in which expression of PIK3CA-H1047R and YFP (and in some conditions loss of p53) was targeted in basal cells using K5CREERT2 or in luminal cells using K8CREERT2 were FACS isolated and RNA was extracted before being hybridized Affymetrix microarrays.