Project description:Epithelial-to-mesenchymal transitions (EMT) underlie a loss of epithelial traits by normal cells during development and neoplastic cells during cancer metastasis. The long noncoding RNA HOTAIR triggers EMT, in part by serving as a scaffold for Polycomb Repressive Complex 2 (PRC2) and thus promoting repressive histone H3 Lys27 methylation. In addition to PRC2, HOTAIR interacts with the Lsd1 lysine demethylase, an epigenetic regulator of cell fate during development and differentiation. Here, we showed that HOTAIR requires the Lsd1-interacting domain, but not the PRC2-interacting domain, to promote migration of epithelial cells. Our results suggest that the HOTAIR-Lsd1 asociation redistributes Lsd1 on chromatin and hence reprograms the epithelial transcriptome.
Project description:Expression of HOX transcript antisense intergenic RNA (HOTAIR)—a long intergenic non-coding RNA (lincRNA)—has been examined in a variety of human cancers, and overexpression of HOTAIR is correlated with poor survival among breast, colon, and liver cancer patients. In this retrospective study, we examine HOTAIR expression in 164 primary breast tumors, from patients who do not receive adjuvant treatment, in a design that is paired with respect to the traditional prognostic markers. We show that HOTAIR expression differs between patients with or without a metastatic endpoint, respectively. Survival analysis shows that high HOTAIR expression in primary tumors is significantly associated with worse prognosis independent of prognostic markers. This association is even stronger when looking only at estrogen receptor (ER)-positive tumor samples. In ER-negative tumor samples, it is not possible to detect a prognostic value of HOTAIR expression. These results are successfully validated in an independent dataset with similar associations. Furthermore, we find that high HOTAIR expression is associated with strong positive expression of multiple neighboring HOXC genes of the HOXC locus on chromosome 12q13.13 and have both negative and positive correlation with other genes located on different chromosomes. Independent datasets verify these significant correlations and thus indicate that HOTAIR might regulate additional genes than those previously reported. In conclusion, our findings suggest that HOTAIR expression may serve as an independent biomarker for the prediction of the risk of metastasis in ER-positive breast cancer patients. 164 breast cancer samples
Project description:HOTAIR is a 2.2 kb long noncoding RNA (lncRNA) whose dysregulation has been linked to oncogenesis, defects in pattern formation during early development, and irregularities during the process of epithelial-to-mesenchymal transition (EMT). However, the oncogenic transformation determined by HOTAIR in vivo and its impact on chromatin dynamics are incompletely understood. Here we generate a transgenic mouse model with doxycycline-inducible expression of human HOTAIR in the context of the MMTV-PyMT breast cancer-prone background (iHOT-PyMT mice) to systematically interrogate the cellular mechanisms by which human HOTAIR lncRNA acts to promote breast cancer progression. We isolated breast cancer cells from the primary tumors of iHOT-PyMT mice (named iHOT+ cells) and performed RNA-seq and ATAC-seq of iHOT+ cells treated with 3 conditions: Dox+, Dox- and DoxWD. We showed that HOTAIR overexpression altered both the cellular transcriptome and chromatin accessibility landscape of multiple metastasis-associated genes and promoted epithelial to mesenchymal transition. These alterations are abrogated within several cell cycles after HOTAIR expression is reverted to basal levels, indicating an erasable lncRNA-associated epigenetic memory. These results suggest that a continual role for HOTAIR in programming a metastatic gene regulatory program.
Project description:HOTAIR is a 2.2 kb long noncoding RNA (lncRNA) whose dysregulation has been linked to oncogenesis, defects in pattern formation during early development, and irregularities during the process of epithelial-to-mesenchymal transition (EMT). However, the oncogenic transformation determined by HOTAIR in vivo and its impact on chromatin dynamics are incompletely understood. Here we generate a transgenic mouse model with doxycycline-inducible expression of human HOTAIR in the context of the MMTV-PyMT breast cancer-prone background (iHOT-PyMT mice) to systematically interrogate the cellular mechanisms by which human HOTAIR lncRNA acts to promote breast cancer progression. We isolated breast cancer cells from the primary tumors of iHOT-PyMT mice (named iHOT+ cells) and performed RNA-seq and ATAC-seq of iHOT+ cells treated with 3 conditions: Dox+, Dox- and DoxWD. We showed that HOTAIR overexpression altered both the cellular transcriptome and chromatin accessibility landscape of multiple metastasis-associated genes and promoted epithelial to mesenchymal transition. These alterations are abrogated within several cell cycles after HOTAIR expression is reverted to basal levels, indicating an erasable lncRNA-associated epigenetic memory. These results suggest that a continual role for HOTAIR in programming a metastatic gene regulatory program.
Project description:Accumulating evidence highlights the role of long non-coding RNAs (lncRNA) in cellular homeostasis, and their dysregulation in disease settings. Most lncRNAs function by interacting with proteins or protein complexes. While several orthogonal methods have been developed to identify these proteins, each method has its inherent strengths and limitations. Here, we combine two RNA-centric methods ChIRP-MS and RNA-BioID to obtain a comprehensive list of proteins that interact with the well-known lncRNA HOTAIR. Overexpression of HOTAIR has been associated with a metastasis-promoting phenotype in various cancers. Although HOTAIR is known to bind with PRC2 and LSD1 protein complexes, an unbiased and comprehensive method to map its interactome has not yet been performed. Both ChIRP-MS and RNA-BioID data sets show an association of HOTAIR with mitoribosomes, suggesting HOTAIR has functions independent of its (post-)transcriptional mode-of-action.
Project description:Accumulating evidence highlights the role of long non-coding RNAs (lncRNA) in cellular homeostasis, and their dysregulation in disease settings. Most lncRNAs function by interacting with proteins or protein complexes. While several orthogonal methods have been developed to identify these proteins, each method has its inherent strengths and limitations. Here, we combine two RNA-centric methods ChIRP-MS and RNA-BioID to obtain a comprehensive list of proteins that interact with the well-known lncRNA HOTAIR. Overexpression of HOTAIR has been associated with a metastasis-promoting phenotype in various cancers. Although HOTAIR is known to bind with PRC2 and LSD1 protein complexes, an unbiased and comprehensive method to map its interactome has not yet been performed. Both ChIRP-MS and RNA-BioID data sets show an association of HOTAIR with mitoribosomes, suggesting HOTAIR has functions independent of its (post-)transcriptional mode-of-action.
Project description:The long-non-coding HOX transcript antisense intergenic RNA (HOTAIR) was identified as significantly upregulated in breast ductal carcinoma in situ (DCIS). The aim of this study was to characterize the phenotypic effects and signaling pathways modulated by HOTAIR in early-stage breast cancer progression. We determined that HOTAIR induces premalignant phenotypic changes by increasing cell proliferation, migration, invasion and in vivo growth in normal and DCIS breast cell lines. Transcriptomic studies (RNA-seq) identified the main signaling pathways modulated by HOTAIR which include bioprocesses related to cell migration, epithelial to mesenchymal transition, extracellular matrix remodeling and activation of HIF1A, AP1 and FGFR signaling pathways among others. Similar pathways were identified as activated in primary invasive breast carcinomas with HOTAIR over-expression. We conclude that HOTAIR over-expression behaves as a positive regulator of cell growth and migration both in normal and DCIS breast cells involved with early-stage breast cancer progression.
Project description:Expression of HOX transcript antisense intergenic RNA (HOTAIR)—a long intergenic non-coding RNA (lincRNA)—has been examined in a variety of human cancers, and overexpression of HOTAIR is correlated with poor survival among breast, colon, and liver cancer patients. In this retrospective study, we examine HOTAIR expression in 164 primary breast tumors, from patients who do not receive adjuvant treatment, in a design that is paired with respect to the traditional prognostic markers. We show that HOTAIR expression differs between patients with or without a metastatic endpoint, respectively. Survival analysis shows that high HOTAIR expression in primary tumors is significantly associated with worse prognosis independent of prognostic markers. This association is even stronger when looking only at estrogen receptor (ER)-positive tumor samples. In ER-negative tumor samples, it is not possible to detect a prognostic value of HOTAIR expression. These results are successfully validated in an independent dataset with similar associations. Furthermore, we find that high HOTAIR expression is associated with strong positive expression of multiple neighboring HOXC genes of the HOXC locus on chromosome 12q13.13 and have both negative and positive correlation with other genes located on different chromosomes. Independent datasets verify these significant correlations and thus indicate that HOTAIR might regulate additional genes than those previously reported. In conclusion, our findings suggest that HOTAIR expression may serve as an independent biomarker for the prediction of the risk of metastasis in ER-positive breast cancer patients.
Project description:The human long noncoding RNA (lncRNA) HOTAIR acts in trans to recruit the Polycomb Repressive Complex 2 (PRC2) to the HOXD gene cluster and promote gene silencing during development. In breast cancers, overexpression of HOTAIR increases metastatic potential via the repression of many additional genes. It has remained unclear what factors determine HOTAIR-dependent PRC2 activity at specific genomic loci, particularly when high levels of HOTAIR result in aberrant gene silencing. To identify additional proteins that contribute to the specific action of HOTAIR, we performed a quantitative proteomic analysis of the HOTAIR interactome. We found that the most specific interaction was between HOTAIR and the heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1, a member of a family of proteins involved in nascent mRNA processing and RNA matchmaking. Our data suggest that A2/B1 are key contributors to HOTAIR-mediated chromatin regulation in breast cancer cells: A2/B1 knockdown reduces HOTAIR-dependent breast cancer cell invasion and decreases PRC2 activity at the majority of HOTAIR-dependent loci. We found that the B1 isoform, which differs from A2 by 12 additional amino acids, binds with highest specificity to HOTAIR. B1 also binds chromatin and associates preferentially with RNA transcripts of HOTAIR gene targets. We furthermore demonstrate a direct RNA-RNA interaction between HOTAIR and a target transcript that is enhanced by B1 binding. Together, these results suggest a model in which B1 matches HOTAIR with transcripts of target genes on chromatin, leading to repression by PRC2.
Project description:HOTAIR is a scafold long non-coding RNA tethering PRC2 and Lsd1/REST/coREST complexes to gene promoters to repress transcription of genes involved in epithelial to mesenchymal transition (EMT). To decipher a role of the Lsd1 in HOTAIR function we generated epithelial cell lines expressing full length and truncated versions of HOTAIR missing first 5'-300 (Epi-HOTΔP) and last 3'-500 bp (Epi-HOTΔL) interacting with HOTAIR partners. These cell lines were further used to determine Lsd1 binding sites using chromatin immunoprecipitation approach.