Endogenous Retroviral Elements in Human Development and Central Nervous System Embryonal Tumors

Human endogenous retroviruses (HERVs), which are critical to normal embryologic development and downregulated during normal maturation, have been implicated in a variety of cancers. Abnormal persistent production of HERVs has been suggested to play a role in oncogenesis and to confer stem cell properties to cells. We recently demonstrated that the most recently incorporated HERV element (HERV-K HML-2) has been associated with the pathogenesis of the embryonal atypical teratoid rhabdoid tumor (AT/RT), shifting our understanding of embryonal tumor development. HML-2 expression is vital for proper human development and its expression is suppressed via methylation or chromatin remodeling as cells differentiate. We previously found that dysfunctional chromatin remodeling due to loss of SMARCB1 expression induces HML-2 envelope (env) expression, impairing cellular differentiation and migration, and facilitating tumor growth in AT/RT. Epigenetic dysregulation in other embryonal tumors with concomitant expression of stem-cell markers may facilitate HML-2 expression. Future studies could utilize HML-2 as potential diagnostic criteria, use its expression as a treatment biomarker, and investigate the efficacy of therapies targeting cells with high HML-2 expression.

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4573 Characterization of vascular disease in an Acta2 mutant mouse model

Journal of Clinical and Translational Science ◽

10.1017/cts.2020.375 ◽

2020 ◽

Vol 4 (s1) ◽

pp. 125-126

Author(s):

Anita Kaw ◽

Callie Kwartler ◽

Abhijnan Chattopadhyay ◽

Dianna M. Milewicz

Keyword(s):

Gene Expression ◽

Stem Cell ◽

Mouse Model ◽

Cell Activation ◽

Mutant Mice ◽

Aortic Tissue ◽

Stem Cell Markers ◽

Cell Markers ◽

And Migration ◽

Proliferation And Migration

OBJECTIVES/GOALS: ACTA2 R179 carriers present with early-onset stroke; occlusive lesions of the distal internal carotid artery and branches are filled with cells staining positive for smooth muscle cell (SMC) markers. We will identify pathways leading to increased SMC proliferation and migration and thus occlusion. METHODS/STUDY POPULATION: We generated an Acta2SMC-R179C/+ mouse model, which expresses the Acta2 R179C mutation in SMCs via the SM22a-Cre-Lox system. rt-PCR performed in aortic tissue confirms the presence of the mutation in the mutant mice and absence in mice with only the floxed allele (WT). We will determine phenotypic differences between mutant and WT brains using micro CT, vascular casting, histology, and immunostaining. We will characterize mutant SMC phenotype in culture by assessing expression of contractile genes and stem cell markers, proliferation, and migration. Single cell RNA (scRNA) sequencing of the brain will assess differential gene expression and cell populations between mutant and WT mice. RESULTS/ANTICIPATED RESULTS: Mutant mice have decreased blood pressure compared to WT mice from 8-24 weeks old, consistent with the phenotype seen in ACTA2 R179 patients. We expect to see occluded and straighter cerebrovascular arteries and white matter changes in the Acta2SMC-R179C/+ mice. iPSC-derived SMCs from patients show de-differentiation, continued expression of stem cell markers, and increased proliferation and migration. We expect to see a similar phenotype in Acta2SMC-R179C/+ mouse SMCs in culture. Via scRNA sequencing, we expect to see altered transcriptional profiles in mutant mice brains including upregulated proliferative pathways in SMCs, glial cell activation, and gene expression changes in neurons. DISCUSSION/SIGNIFICANCE OF IMPACT: These studies will contribute important information on the pathogenesis of the cerebrovascular disease in ACTA2 R179 patients. These results may aid in identifying treatments to prevent or decrease risk of developing strokes in those with known predisposition to cerebrovascular occlusive disease.

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Analysis of Dual Class I Histone Deacetylase and Lysine Demethylase Inhibitor Domatinostat (4SC-202) on Growth and Cellular and Genomic Landscape of Atypical Teratoid/Rhabdoid

Cancers ◽

10.3390/cancers12030756 ◽

2020 ◽

Vol 12 (3) ◽

pp. 756 ◽

Cited By ~ 5

Author(s):

Mariah M. Hoffman ◽

Jessica S. Zylla ◽

Somshuvra Bhattacharya ◽

Kristin Calar ◽

Timothy W. Hartman ◽

...

Keyword(s):

Stem Cell ◽

Single Cell ◽

Class I ◽

Specific Cell ◽

Normal Brain ◽

Stem Cell Markers ◽

Sequencing Data ◽

Aberrant Expression ◽

Atypical Teratoid ◽

Lysine Demethylase

Central nervous system atypical teratoid/rhabdoid tumors (ATRTs) are rare and aggressive tumors with a very poor prognosis. Current treatments for ATRT include resection of the tumor, followed by systemic chemotherapy and radiation therapy, which have toxic side effects for young children. Gene expression analyses of human ATRTs and normal brain samples indicate that ATRTs have aberrant expression of epigenetic markers including class I histone deacetylases (HDAC’s) and lysine demethylase (LSD1). Here, we investigate the effect of a small molecule epigenetic modulator known as Domatinostat (4SC-202), which inhibits both class I HDAC’s and Lysine Demethylase (LSD1), on ATRT cell survival and single cell heterogeneity. Our findings suggest that 4SC-202 is both cytotoxic and cytostatic to ATRT in 2D and 3D scaffold cell culture models and may target cancer stem cells. Single-cell RNA sequencing data from ATRT-06 spheroids treated with 4SC-202 have a reduced population of cells overexpressing stem cell-related genes, including SOX2. Flow cytometry and immunofluorescence on 3D ATRT-06 scaffold models support these results suggesting that 4SC-202 reduces expression of cancer stem cell markers SOX2, CD133, and FOXM1. Drug-induced changes to the systems biology landscape are also explored by multi-omics enrichment analyses. In summary, our data indicate that 4SC-202 has both cytotoxic and cytostatic effects on ATRT, targets specific cell sub-populations, including those with cancer stem-like features, and is an important potential cancer therapeutic to be investigated in vivo.

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