Project description:Transposable elements (TEs) are enriched in cytosine methylation, preventing their mobility within the genome. Two examples of TEs that escape this regulation are the murine-specific intracisternal A particle (IAP) elements Avy and AxinFu, which exhibit inter-individual variability in methylation associated with phenotypic variation. To determine the frequency of this phenomenon, its underlying mechanisms, and its effects on gene expression, we previously conducted a screen identifying variably methylated IAPs (VM-IAPs). Here, we fully validate these elements, categorising VM-IAPs for the first time into those exhibiting tissue specificity (tsVM-IAPs) and those showing uniform methylation among tissues (constitutive- or cVM-IAPs) with both types having the potential to regulate the genome in cis. Using our validated set of VM-IAPs, we explore how variable methylation is established and identify sequences enriched within cVM-IAPs, implicating genetics as a determinant of variability. CTCF, a methylation-sensitive transcription factor known for its role in facilitating chromatin interactions, is enriched at VM-IAPs and we show that CTCF binding is inversely correlated with methylation at cVM-IAPs. We uncover dynamic physical interactions between lowly-methylated cVM-IAPs and other genomic loci, suggesting that VM-IAPs have the potential for long-range genomic regulation. Lastly, screening for variably methylated regions in other TEs shows that this phenomenon is largely limited to IAPs, which are amongst the youngest and most active endogenous retroviruses. We propose that a recently evolved interplay between genetic sequence, CTCF binding, and DNA methylation at young TEs has the potential to cause inter-individual variability in transcriptional outcomes with implications for phenotypic variation.
Project description:Cell migration is an instrumental process that ensures cells are properly positioned to support the specification of distinct tissue types during development. To provide insight, we used fluorescence activated cell sorting (FACS) to isolate two migrating cell types from the Drosophila embryo: caudal visceral mesoderm (CVM) cells, precursors of longitudinal muscles of the gut, and hemocytes (HCs), the Drosophila equivalent of blood cells. ~350 genes were identified from each of the sorted samples using RNA-seq, and in situ hybridization was used to confirm expression within each cell type or, alternatively, within other interacting, co-sorted cell types. To start, the two gene expression profiling datasets were compared to identify cell migration regulators that are potentially generally-acting. 73 genes were present in both CVM cell and HC gene expression profiles, including the transcription factor zinc finger homeodomain-1 (zfh1). Comparisons with gene expression profiles of Drosophila border cells that migrate during oogenesis had a more limited overlap, with only the genes neyo (neo) and singed (sn) found to be expressed in border cells as well as CVM cells and HCs, respectively. Neo encodes a protein with Zona pellucida domain linked to cell polarity, while sn encodes an actin binding protein. Tissue specific RNAi expression coupled with live in vivo imaging was used to confirm cell-autonomous roles for zfh1 and neo in supporting CVM cell migration, whereas previous studies had demonstrated a role for Sn in supporting HC migration. In addition, comparisons were made to migrating cells from vertebrates. Seven genes were found expressed by chick neural crest cells, CVM cells, and HCs including extracellular matrix (ECM) proteins and proteases. In summary, we show that genes shared in common between CVM cells, HCs, and other migrating cell types can help identify regulators of cell migration. Our analyses show that neo in addition to zfh1 and sn studied previously impact cell migration. This study also suggests that modification of the extracellular milieu may be a fundamental requirement for cells that undergo cell streaming migratory behaviors.
Project description:Tamoxifen, which is used to treat breast cancer, increases the risks of endometrial cancer. In this study, we performed a genome-wide assessment of ERα-chromatin interactions in surgical specimens obtained from patients with tamoxifen-associated endometrial cancer. ERα was found at active enhancers in endometrial cancer cells as marked by the presence of RNA polymerase II and the histone marker H3K27Ac. Our results define conserved sites for genomic interplay between FOXA1 and ERα in breast cancer and tamoxifen-associated endometrial cancer.
Project description:The identification of target genes at genome-wide association study (GWAS) loci is a major obstacle for GWAS follow-up. To identify candidate target genes at the 16 known endometrial cancer GWAS risk loci, we performed HiChIP chromatin looping analysis of endometrial cell lines. To enrich for enhancer-promoter interactions, a mechanism through which GWAS variation may target genes, we captured loops associated with H3K27Ac histone, characteristic of promoters and enhancers. Analysis of HiChIP loops contacting promoters revealed enrichment for endometrial cancer GWAS heritability and intersection with endometrial cancer risk variation identified 103 HiChIP target genes at 13 risk loci. Expression of four HiChIP target genes (SNX11, SRP14, HOXB2 and BCL11A) was associated with risk variation, providing further evidence for their regulation. Network analysis functionally prioritized a set of proteins that interact with those encoded by HiChIP target genes, and this set was enriched for pan-cancer and endometrial cancer drivers. Lastly, HiChIP target genes and prioritized interacting proteins were over-represented in pathways related to endometrial cancer development. In summary, we have generated the first global chromatin looping data from endometrial cells, enabling analysis of all known endometrial cancer risk loci and identifying biologically relevant candidate target genes.
Project description:Tamoxifen, a small molecule inhibitor that binds the Estrogen Receptor alpha (ERα), blocks breast cancer progression while increasing the risk for endometrial cancer. In this study, we assessed genome-wide ERα-chromatin interactions in surgical specimens of endometrial tumors from patients who were previously treated for breast cancer with tamoxifen, and endometrial tumors from patients who were treated without tamoxifen. We compared ERα and signal at differential ERα sites in endometrial tumors of nine patients who received tamoxifen with endometrial tumors with six patients who never used tamoxifen. In addition, we performed H3K27ac (a marker for activity) ChIPs on the above mentioned endometrial tumors, and assed this signal at differential ERα sites. Compared to endometrial tumors of non-users, tamoxifen-associated endometrial tumors exposed higher H3K27ac intensities at ERα sites that are enriched in tamoxifen-associated endometrial tumors. Four tamoxifen-associated endometrial tumors that we used in our analysis have been previously published as Tumor A, B, D, and E in GSE81213.
Project description:Using H3K27ac ChIP-seq profile to map active enhancers in lung cancer and endometrial carcinoma cells ChIP-seq of H3K27ac was done in lung adenocarcinoma cell lines (NCI-H358 and NCI-H2009), squamous cell lung carcinoma cell lines (HCC95) and endometrial carcinoma cell lines (Ishikawa)
Project description:Full title: comparison of the genomic (arrayCGH) profiles of endometrial cancer with and without prior prolonged tamoxifen treatment for primary breast cancer Purpose: Tamoxifen has been a very effective treatment for breast cancer for several decades, however, at the same time increases the risk of endometrial cancer, especially after prolonged exposure. In addition, tamoxifen has been associated with a higher proportion of unfavorable uterine tumor subtypes (carcinosarcomas and serous adenocarcinomas) with worse survival. We investigated whether endometrial tumors, which developed after prolonged tamoxifen treatment for breast cancer, are genetically different from endometrial tumors without preceding tamoxifen exposure. Experimental design: Array CGH was used on archival formalin-fixed paraffin embedded (FFPE) endometrial tumors to determine genomic aberrations. We compared the genomic profiles of 52 endometrial tumors from breast cancer patients after long-term (>=2 years) tamoxifen use (endometrioid adenocarcinomas n=26, carcinosarcomas n=14 and serous adenocarcinomas n=12) with endometrial tumors from unexposed breast cancer patients (n=45). Genomic profiles were correlated with tamoxifen exposure, tumor subtypes and histopathological characteristics of the endometrial tumors. Results: The common uterine corpus cancers of the endometrioid subtype show few genomic aberrations. Tumors with many genomic aberrations were in general ER-negative. In contrast, carcinosarcomas and serous adenocarcinomas showed many aberrations, however they were indistinguishable from each other. Tumors that developed after prolonged tamoxifen use did not show more or different aberrations than unexposed tumors. This was true for all tumor subtypes. Conclusion: Endometrial carcinomas that develop after prolonged tamoxifen use can not be distinguished from non-users on basis of their tumor genomic profile.