Darawalee Wangsa

Detection of Genomic Amplification of the Human Telomerase Gene TERC, a Potential Marker for Triage of Women with HPV-Positive, Abnormal Pap Smears

The vast majority of invasive cervical carcinomas harbor additional copies of the chromosome arm 3q, resulting in genomic amplification of the human telomerase gene TERC. Here, we evaluated TERC amplification in routinely collected liquid based cytology (LBC) samples with histologically confirmed diagnoses. A set of 78 LBC samples from a Swedish patient cohort were analyzed with a four-color fluorescence in situ hybridization probe panel that included TERC. Clinical follow-up included additional histological evaluation and Pap smears. Human papillomavirus status was available for all cases. The correlation of cytology, TERC amplification, human papillomavirus typing, and histological diagnosis showed that infection with high-risk human papillomavirus was detected in 64% of the LBC samples with normal histopathology, in 65% of the cervical intraepithelial neoplasia (CIN)1, 95% of the CIN2, 96% of the CIN3 lesions, and all carcinomas. Seven percent of the lesions with normal histopathology were positive for TERC amplification, 24% of the CIN1, 64% of the CIN2, 91% of the CIN3 lesions, and 100% of invasive carcinomas. This demonstrates that detection of genomic amplification of TERC in LBC samples can identify patients with histopathologically confirmed CIN3 or cancer. Indeed, the proportion of TERC-positive cases increases with the severity of dysplasia. Among the markers tested, detection of TERC amplification in cytological samples has the highest combined sensitivity and specificity for discernment of low-grade from high-grade dysplasia and cancer.

Loss of lamin B1 results in prolongation of S phase and decondensation of chromosome territories

Nuclear lamin B1 (LMNB1) constitutes one of the major structural proteins in the lamina mesh. We silenced the expression of LMNB1 by RNA interference in the colon cancer cell line DLD‐1 and showed a dramatic redistribution of H3K27me3 from the periphery to a more homogeneous nuclear dispersion. In addition, we observed telomere attrition and an increased frequency of micronuclei and nuclear blebs. By 3D‐FISH analyses, we demonstrated that the volume and surface of chromosome territories were significantly larger in LMNB1‐depleted cells, suggesting that LMNB1 is required to maintain chromatin condensation in interphase nuclei. These changes led to a prolonged S phase due to activation of Chk1. Finally, silencing of LMNB1 resulted in extensive changes in alternative splicing of multiple genes and in a higher number of enlarged nuclear speckles. Taken together, our results suggest a mechanistic role of the nuclear lamina in the organization of chromosome territories, maintenance of genome integrity and proper gene splicing.—Camps, J., Wangsa, D., Falke, M., Brown, M., Case, C. M., Erdos, M. R., Ried, T. Loss of lamin B1 results in prolongation of S phase and decondensation of chromosome territories. FASEB J. 28, 3423–3434 (2014). www.fasebj.org

HiCTMap: Detection and analysis of chromosome territory structure and position by high-throughput imaging

The spatial organization of chromosomes in the nuclear space is an extensively studied field that relies on measurements of structural features and 3D positions of chromosomes with high precision and robustness. However, no tools are currently available to image and analyze chromosome territories in a high-throughput format. Here, we have developed High-throughput Chromosome Territory Mapping (HiCTMap), a method for the robust and rapid analysis of 2D and 3D chromosome territory positioning in mammalian cells. HiCTMap is a high-throughput imaging-based chromosome detection method which enables routine analysis of chromosome structure and nuclear position. Using an optimized FISH staining protocol in a 384-well plate format in conjunction with a bespoke automated image analysis workflow, HiCTMap faithfully detects chromosome territories and their position in 2D and 3D in a large population of cells per experimental condition. We apply this novel technique to visualize chromosomes 18, X, and Y in male and female primary human skin fibroblasts, and show accurate detection of the correct number of chromosomes in the respective genotypes. Given the ability to visualize and quantitatively analyze large numbers of nuclei, we use HiCTMap to measure chromosome territory area and volume with high precision and determine the radial position of chromosome territories using either centroid or equidistant-shell analysis. The HiCTMap protocol is also compatible with RNA FISH as demonstrated by simultaneous labeling of X chromosomes and Xist RNA in female cells. We suggest HiCTMap will be a useful tool for routine precision mapping of chromosome territories in a wide range of cell types and tissues.

Transformation of Accessible Chromatin and 3D Nucleome Underlies Lineage Commitment of Early T Cells

Summary How chromatin reorganization coordinates differentiation and lineage commitment from hematopoietic stem and progenitor cells (HSPCs) to mature immune cells has not been well understood. Here, we carried out an integrative analysis of chromatin accessibility, topologically associating domains, AB compartments, and gene expression from HSPCs to CD4+CD8+ T cells. We found that abrupt genome‐wide changes at all three levels of chromatin organization occur during the transition from double‐negative stage 2 (DN2) to DN3, accompanying the T lineage commitment. The transcription factor BCL11B, a critical regulator of T cell commitment, is associated with increased chromatin interaction, and Bcl11b deletion compromised chromatin interaction at its target genes. We propose that these large‐scale and concerted changes in chromatin organization present an energy barrier to prevent the cell from reversing its fate to earlier stages or redirecting to alternatives and thus lock the cell fate into the T lineages. Graphical Abstract Figure. No Caption available. HighlightsCommitment to T lineages is paired with global changes in the regulome and 3D nucleomeTransformation of these chromatin organizations is concerted for T cell commitmentConcerted changes of the regulome and 3D nucleome underlie transcriptomic changesBCL11B contributes to the maintenance of the 3D nucleome in T cells &NA; Cellular differentiation and cell‐fate choice involve substantial chromatin reorganization. Through an integrative analysis of the regulome, 3D nucleome, and transcriptome, Hu and Cui et al. uncover abrupt global changes in the regulome and 3D nucleome at the DN2‐to‐DN3 transition, establishing a chromatin barrier to lock cell fate into the T lineages.

An Improved Breast Epithelial Sampling Method for Molecular Profiling and Biomarker Analysis in Women at Risk for Breast Cancer

Background There is a strong need to define the molecular changes in normal at-risk breast epithelium to identify biomarkers and new targets for breast cancer prevention and to develop a molecular signature for risk assessment. Improved methods of breast epithelial sampling are needed to promote whole-genome molecular profiling, increase ductal epithelial cell yield, and reduce sample cell heterogeneity. Methods We developed an improved method of breast ductal sampling with ductal lavage through a 22-gauge catheter and collection of ductal samples with a microaspirator. Women at normal risk or increased risk for breast cancer were studied. Ductal epithelial samples were analyzed for cytopathologic changes, cellular yield, epithelial cell purity, quality and quantity of DNA and RNA, and use in multiple downstream molecular applications. Results We studied 50 subjects, including 40 subjects at normal risk for breast cancer and 37 subjects with non-nipple aspirate fluid-yielding ducts. This method provided multiple 1.0 mL samples of high ductal epithelial cell content (median ≥8 samples per subject of ≥5,000 cells per sample) with 80%–100% epithelial cell purity. Extraction of a single intact ductal sample (fluid and cells) or the separate frozen cellular component provided DNA and RNA for multiple downstream studies, including quantitative reverse transcription-polymerase chain reaction (PCR) for microRNA, quantitative PCR for the human telomerase reverse transcriptase gene, whole-genome DNA amplification, and array comparative genomic hybridization analysis. Conclusion An improved breast epithelial sampling method has been developed, which should significantly expand the acquisition and biomarker analysis of breast ductal epithelium in women at risk for breast cancer.

A Muscle-Specific Enhancer RNA Mediates Cohesin Recruitment and Regulates Transcription In trans

The enhancer regions of the myogenic master regulator MyoD give rise to at least two enhancer RNAs. Core enhancer eRNA (CEeRNA) regulates transcription of the adjacent MyoD gene, whereas DRReRNA affects expression of Myogenin in trans. We found that DRReRNA is recruited at the Myogenin locus, where it colocalizes with Myogenin nascent transcripts. DRReRNA associates with the cohesin complex, and this association correlates with its transactivating properties. Despite being expressed in undifferentiated cells, cohesin is not loaded on Myogenin until the cells start expressing DRReRNA, which is then required for cohesin chromatin recruitment and maintenance. Functionally, depletion of either cohesin or DRReRNA reduces chromatin accessibility, prevents Myogenin activation, and hinders muscle cell differentiation. Thus, DRReRNA ensures spatially appropriate cohesin loading in trans to regulate gene expression.

SMYD5 Controls Heterochromatin and Chromosome Integrity during Embryonic Stem Cell Differentiation

Epigenetic regulation of chromatin states is thought to control gene expression programs during lineage specification. However, the roles of repressive histone modifications, such as trimethylated histone lysine 20 (H4K20me3), in development and genome stability are largely unknown. Here, we show that depletion of SET and MYND domain-containing protein 5 (SMYD5), which mediates H4K20me3, leads to genome-wide decreases in H4K20me3 and H3K9me3 levels and derepression of endogenous LTR- and LINE-repetitive DNA elements during differentiation of mouse embryonic stem cells. SMYD5 depletion resulted in chromosomal aberrations and the formation of transformed cells that exhibited decreased H4K20me3 and H3K9me3 levels and an expression signature consistent with multiple human cancers. Moreover, dysregulated gene expression in SMYD5 cancer cells was associated with LTR and endogenous retrovirus elements and decreased H4K20me3. In addition, depletion of SMYD5 in human colon and lung cancer cells results in increased tumor growth and upregulation of genes overexpressed in colon and lung cancers, respectively. These findings implicate an important role for SMYD5 in maintaining chromosome integrity by regulating heterochromatin and repressing endogenous repetitive DNA elements during differentiation. Cancer Res; 77(23); 6729-45. ©2017 AACR.

Trac-looping measures genome structure and chromatin accessibility

Long-range chromatin interactions play critical roles in genome organization and regulation of transcription. We now report transposase-mediated analysis of chromatin looping (Trac-looping) for simultaneous detection of multiscale genome-wide chromatin interactions among regulatory elements and chromatin accessibility. With this technique, a bivalent oligonucleotide linker is inserted between two interacting regions such that the chromatin interactions are captured without prior chromatin fragmentation and proximity-based ligation. Application of Trac-looping to human CD4+ T cells revealed substantial reorganization of enhancer–promoter interactions associated with changes in gene expression after T cell receptor stimulation.Insertion of a bivalent linker between two regions of interest allows chromatin contacts to be probed without proximity ligation.

Dynamics of Genome Alterations in Crohn's Disease–Associated Colorectal Carcinogenesis

Purpose: Patients with inflammatory bowel diseases, that is, ulcerative colitis and Crohns disease (CD), face an increased risk of developing colorectal cancer (CRC). Evidence, mainly from ulcerative colitis, suggests that TP53 mutations represent an initial step in the progression from inflamed colonic epithelium to CRC. However, the pathways involved in the evolution of CRC in patients with CD are poorly characterized. Experimental Design: Here, we analyzed 73 tissue samples from 28 patients with CD-CRC, including precursor lesions, by targeted next-generation sequencing of 563 cancer-related genes and array-based comparative genomic hybridization. The results were compared with 24 sporadic CRCs with similar histomorphology (i.e., mucinous adenocarcinomas), and to The Cancer Genome Atlas data (TCGA). Results: CD-CRCs showed somatic copy-number alterations (SCNAs) similar to sporadic CRCs with one notable exception: the gain of 5p was significantly more prevalent in CD-CRCs. CD-CRCs had a distinct mutation signature: TP53 (76% in CD-CRCs vs. 33% in sporadic mucinous CRCs), KRAS (24% vs. 50%), APC (17% vs. 75%), and SMAD3 (3% vs. 29%). TP53 mutations and SCNAs were early and frequent events in CD progression, while APC, KRAS, and SMAD2/4 mutations occurred later. In four patients with CD-CRC, at least one mutation and/or SCNAs were already present in non-dysplastic colonic mucosa, indicating occult tumor evolution. Conclusions: Molecular profiling of CD-CRCs and precursor lesions revealed an inflammation-associated landscape of genome alterations: 5p gains and TP53 mutations occurred early in tumor development. Detection of these aberrations in precursor lesions may help predicting disease progression and distinguishes CD-associated from sporadic colorectal neoplasia. Clin Cancer Res; 24(20); 4997–5011. ©2018 AACR.

Abstract 1438: The dynamics of genetic aberrations in Crohn's disease associated colorectal carcinogenesis

Crohn’s disease, a condition of chronic inflammation of the intestine, significantly increases the risk for the development of colorectal cancer (CRC). Sporadic CRCs are characterized by a specific pattern of genomic imbalances and a landscape of acquired gene mutations. In this study we aimed to compare CRCs that arise as a consequence of chronic inflammation in Crohn’s disease with sporadic CRCs. We analyzed 26 Crohn’s disease associated CRCs, four matched dysplastic lesions, six matched inflamed mucosa samples, and two matched lymph node metastases using array comparative genomic hybridization, targeted sequencing (564 cancer related genes) and gene expression profiling. As a control, we used normal intestinal mucosa from the resection margin of these CRCs and 24 sporadic CRCs. In general, CRCs that developed in patients with Crohn’s disease had a similar distribution of genomic imbalances compared to sporadic CRC. However, we identified distinct mutation signatures: in the Crohn9s disease associated CRCs the most frequently mutated gene was TP53, which occurred in 65% of the samples. The second, third and fourth most frequently mutated genes were KRAS (27%), APC (23%) and PIK3CA (19%). In the control group of sporadically arising CRCs, the most commonly mutated gene was APC (75%), followed by KRAS (54%), TP53 (33%), SMAD3 (29%) and SMAD2 (25%). The genetic analyses of multiple lesions from individual patients revealed a high degree of intertumoral heterogeneity with diverse patterns of gene mutations and allowed the reconstruction of the sequence of genetic events during Crohn’s disease associated tumorigenesis. In contrast to sporadic colorectal carcinogenesis, TP53 mutations were observed as early and common events while APC mutations occurred rather late and were infrequent. Our comprehensive molecular profiling of Crohn’s disease associated CRCs suggests that the genetic landscape of CRC is influenced by the activation of inflammation related pathways. Furthermore, our findings offer potential for establishing an early detection marker for dysplasia in patients with Crohn’s disease. Citation Format: Daniela D. Hirsch, Darawalee Wangsa, Yue Hu, Jack Zhu, David Petersen, Daniel C. Edelman, Paul S. Meltzer, Bao Tran, Kerstin Heselmeyer-Haddad, Thomas Ried, Timo Gaiser. The dynamics of genetic aberrations in Crohn9s disease associated colorectal carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1438. doi:10.1158/1538-7445.AM2017-1438