Publications by authors named "Yasemin Kaygusuz"

4 Publications

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L1CAM defines the regenerative origin of metastasis-initiating cells in colorectal cancer.

Nat Cancer 2020 Jan 13;1(1):28-45. Epub 2020 Jan 13.

Cancer Biology and Genetics Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.

Metastasis-initiating cells with stem-like properties drive cancer lethality, yet their origins and relationship to primary-tumor-initiating stem cells are not known. We show that L1CAM cells in human colorectal cancer (CRC) have metastasis-initiating capacity, and we define their relationship to tissue regeneration. L1CAM is not expressed in the homeostatic intestinal epithelium, but is induced and required for epithelial regeneration following colitis and in CRC organoid growth. By using human tissues and mouse models, we show that L1CAM is dispensable for adenoma initiation but required for orthotopic carcinoma propagation, liver metastatic colonization and chemoresistance. L1CAM cells partially overlap with LGR5 stem-like cells in human CRC organoids. Disruption of intercellular epithelial contacts causes E-cadherin-REST transcriptional derepression of L1CAM, switching chemoresistant CRC progenitors from an L1CAM to an L1CAM state. Thus, L1CAM dependency emerges in regenerative intestinal cells when epithelial integrity is lost, a phenotype of wound healing deployed in metastasis-initiating cells.
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http://dx.doi.org/10.1038/s43018-019-0006-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7351134PMC
January 2020

Stable inhibitory activity of regulatory T cells requires the transcription factor Helios.

Science 2015 Oct;350(6258):334-9

Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA. Department of Microbiology and Immunobiology, Division of Immunology, Harvard Medical School, Boston MA.

The maintenance of immune homeostasis requires regulatory T cells (T(regs)). Given their intrinsic self-reactivity, T(regs) must stably maintain a suppressive phenotype to avoid autoimmunity. We report that impaired expression of the transcription factor (TF) Helios by FoxP3(+) CD4 and Qa-1-restricted CD8 T(regs) results in defective regulatory activity and autoimmunity in mice. Helios-deficient T(regs) develop an unstable phenotype during inflammatory responses characterized by reduced FoxP3 expression and increased effector cytokine expression secondary to diminished activation of the STAT5 pathway. CD8 T(regs) also require Helios-dependent STAT5 activation for survival and to prevent terminal T cell differentiation. The definition of Helios as a key transcription factor that stabilizes T(regs) in the face of inflammatory responses provides a genetic explanation for a core property of T(regs).
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http://dx.doi.org/10.1126/science.aad0616DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4627635PMC
October 2015

Distinct EMT programs control normal mammary stem cells and tumour-initiating cells.

Nature 2015 Sep 2;525(7568):256-60. Epub 2015 Sep 2.

Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.

Tumour-initiating cells (TICs) are responsible for metastatic dissemination and clinical relapse in a variety of cancers. Analogies between TICs and normal tissue stem cells have led to the proposal that activation of the normal stem-cell program within a tissue serves as the major mechanism for generating TICs. Supporting this notion, we and others previously established that the Slug epithelial-to-mesenchymal transition-inducing transcription factor (EMT-TF), a member of the Snail family, serves as a master regulator of the gland-reconstituting activity of normal mammary stem cells, and that forced expression of Slug in collaboration with Sox9 in breast cancer cells can efficiently induce entrance into the TIC state. However, these earlier studies focused on xenograft models with cultured cell lines and involved ectopic expression of EMT-TFs, often at non-physiological levels. Using genetically engineered knock-in reporter mouse lines, here we show that normal gland-reconstituting mammary stem cells residing in the basal layer of the mammary epithelium and breast TICs originating in the luminal layer exploit the paralogous EMT-TFs Slug and Snail, respectively, which induce distinct EMT programs. Broadly, our findings suggest that the seemingly similar stem-cell programs operating in TICs and normal stem cells of the corresponding normal tissue are likely to differ significantly in their details.
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http://dx.doi.org/10.1038/nature14897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4764075PMC
September 2015

Epigenetic mechanisms underlying the dynamic expression of cancer-testis genes, PAGE2, -2B and SPANX-B, during mesenchymal-to-epithelial transition.

PLoS One 2014 17;9(9):e107905. Epub 2014 Sep 17.

Department of Molecular Biology and Genetics, Bilkent University, Ankara, Turkey.

Cancer-testis (CT) genes are expressed in various cancers but not in normal tissues other than in cells of the germline. Although DNA demethylation of promoter-proximal CpGs of CT genes is linked to their expression in cancer, the mechanisms leading to demethylation are unknown. To elucidate such mechanisms we chose to study the Caco-2 colorectal cancer cell line during the course of its spontaneous differentiation in vitro, as we found CT genes, in particular PAGE2, -2B and SPANX-B, to be up-regulated during this process. Differentiation of these cells resulted in a mesenchymal-to-epithelial transition (MET) as evidenced by the gain of epithelial markers CDX2, Claudin-4 and E-cadherin, and a concomitant loss of mesenchymal markers Vimentin, Fibronectin-1 and Transgelin. PAGE2 and SPAN-X up-regulation was accompanied by an increase in Ten-eleven translocation-2 (TET2) expression and cytosine 5-hydroxymethylation as well as the disassociation of heterochromatin protein 1 and the polycomb repressive complex 2 protein EZH2 from promoter-proximal regions of these genes. Reversal of differentiation resulted in down-regulation of PAGE2, -2B and SPANX-B, and induction of epithelial-to-mesenchymal transition (EMT) markers, demonstrating the dynamic nature of CT gene regulation in this model.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0107905PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4168264PMC
December 2015