Researcher:
Bayram, Özlem Yedier

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Özlem Yedier

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Bayram

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Bayram, Özlem Yedier

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2020 - 20224

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    Overcoming chemoresistance in triple negative breast cancer by bromodomain inhibition
    (Elsevier Sci Ltd, 2022) Philpott, M.; Cribbs, A.; Oppermann, U.; Onder, T. T.; Department of Molecular Biology and Genetics; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; Bayram, Özlem Yedier; Cingöz, Ahmet; Aksu, Ali Cenk; Değirmenci, Nareg Pınarbaşı; Esin, Beril; Kayabölen, Alişan; Cevatemre, Buse; Ayhan, Ceyda Açılan; Önder, Tuğba Bağcı; Researcher; Researcher; PhD Student; PhD Student; Master Student; PhD Student; Researcher; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; College of Engineering; Graduate School of Health Sciences; Graduate School of Health Sciences; Graduate School of Health Sciences; Graduate School of Health Sciences; Graduate School of Health Sciences; N/A; School of Medicine; School of Medicine; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 219658; 184359
    Background: Triple negative breast cancer (TNBC) is an aggressive subtypeofbreastcancerwithpoorprognosis.TNBCcellsdonotexpress receptorsforestrogen,progesteroneorHer2,eliminatingthepossibilityof targetedtherapyapplications.Therefore,current treatmentoptionforTNBC is limitedwithsurgery followedbyconventional chemotherapy.However, acquiredresistancetochemotherapyisamajorchallengethatisassociated withrelapse,whichisdrivenbycoordinatedactionsofgeneticandepigenetic events. MaterialsandMethods:Weaimedtoelucidatetherolesoffullspectrum ofepigeneticmodifiersinmaintenanceandreversionofchemoresistancein TNBC.TogenerateinvitromodelsofchemoresistantTNBC,weexposed3 different TNBC cell lines to escalating doses of taxane (paclitaxel). Transcriptome analysis by RNA-sequencingwere performed to reveal changesthat regulatechemoresistance.Withourcustomepigenome-wide CRISPR-Cas9library(EpigeneticKnock-OutLibrary-EPIKOL)targetingall chromatinreaders,writers,erasersandassociatedproteins,wesystematicallyinterrogatedtherolesofepigeneticmodifiersinchemoresistantTNBC cells.Wealsoconductedmediumscalechemicalscreensutilizingepigenetic probelibrariesinchemoresistantcells. Results:RNAsequencingonpairedsensitiveandchemoresistancecell linesrevealedABCB1upregulationasamajordriverofresistance.Inhibition of themembersofMLLandSWI/SNFcomplexes, aswell as thegenes relatedwithhistoneubiquitinationandacetyl-mark readers re-sensitized chemoresistantcellstopaclitaxel.Amemberof thebromodomainprotein family,BRPF1,cameasacommonhit inourchemical screenaswellas geneticscreens.KnockoutofBRPF1or itschemical inhibitioncompletely abolishedpaclitaxel resistanceandmodulatedABCB1expression. Conclusions:ThroughEPIKOLscreensonchemoresistantTNBCcells coupledwithchemicalscreens,weidentifiednovelepigeneticmodifiersthat arecrucial formaintainingandovercomingdrug resistance.Collectively, thesefindingsprovideabasistodevelopcombinationtherapiestoefficiently killchemoresistantTNBC.
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    Loss of PRC2 or KMT2D-COMPASS generates two quasi-mesenchymal cell states with distinct metastatic abilities
    (American Association for Cancer Research (AACR), 2020) Zhang, Yun; Donaher, Joana Liu; Das, Sunny; Li, Xin; Reinhardt, Ferenc; Krall, Jordan A.; Lambert, Arthur W.; Thiru, Prathapan; Keys, Heather R.; Khan, Mehreen; Hofree, Matan; Wilson, Molly M.; Tyler, Michael; Tirosh, Itay; Regev, Aviv; Lees, Jacqueline; Weinberg, Robert A.; Bayram, Özlem Yedier; Lack, Nathan Alan; Önder, Tamer Tevfik; Önder, Tuğba Bağcı; Researcher; Faculty Member; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); N/A; N/A; N/A; N/A; School of Medicine; School of Medicine; School of Medicine; N/A; 120842; 42946; 184359
    The epithelial-mesenchymal transition (EMT) is a key cell-biological program enabling carcinoma cell phenotypic plasticity. Accumulating evidence suggests EMT programs do not operate as a stereotypical program that functions as a binary switch, shifting cells from an epithelial (E) to a mesenchymal (M) state. Instead, EMT programs generate cells that enter into a series of intermediate states arrayed along the E-M phenotypic spectrum. At present, we still lack a coherent understanding of how carcinoma cells control their entrance into and residence in these various intermediate states, and which EMT intermediate state(s) favour the metastatic process. Here we characterize a new level of regulation of EMT, consisting of two chromatin-modifying complexes, PRC2 and KMT2D-COMPASS, that function as critical regulators to maintain stable residence of both normal and neoplastic cells in an epithelial state via regulating the downstream response of EMT-inducing signals. Dysfunction of either of these two complexes causes cells that were previously stably ensconced in an epithelial state to lapse into two distinct quasi-mesenchymal cell states with strongly differing metastatic abilities. These observations uncover a novel mechanism that regulates E-M plasticity, specifies which intermediate EMT state a cell will reside in, and thereby determines the metastatic ability of carcinoma cells.
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    Genome-wide CRISPR screen identifies PRC2 and KMT2D-COMPASS as regulators of distinct EMT trajectories that contribute differentially to metastasis
    (Nature Portfolio, 2022) Zhang, Yun; Donaher, Joana Liu; Das, Sunny; Li, Xin; Reinhardt, Ferenc; Krall, Jordan A.; Lambert, Arthur W.; Thiru, Prathapan; Keys, Heather R.; Khan, Mehreen; Hofree, Matan; Wilson, Molly M.; Tyler, Michael; Tirosh, Itay; Regev, Aviv; Lees, Jacqueline A.; Weinberg, Robert A.; N/A; Lack, Nathan Alan; Bayram, Özlem Yedier; Önder, Tamer Tevfik; Önder, Tuğba Bağcı; Faculty Member; Researcher; Faculty Member; Faculty Member; School of Medicine; School of Medicine; School of Medicine; School of Medicine; 120842; N/A; 42946; 184359
    Through genome-wide and focused CRISPR screens, Zhang et al. discover that loss of PRC2 or KMT2D-COMPASS enables distinct EMT trajectories, which exert differential effects on the metastatic capability of carcinoma cells. Epithelial-mesenchymal transition (EMT) programs operate within carcinoma cells, where they generate phenotypes associated with malignant progression. In their various manifestations, EMT programs enable epithelial cells to enter into a series of intermediate states arrayed along the E-M phenotypic spectrum. At present, we lack a coherent understanding of how carcinoma cells control their entrance into and continued residence in these various states, and which of these states favour the process of metastasis. Here we characterize a layer of EMT-regulating machinery that governs E-M plasticity (EMP). This machinery consists of two chromatin-modifying complexes, PRC2 and KMT2D-COMPASS, which operate as critical regulators to maintain a stable epithelial state. Interestingly, loss of these two complexes unlocks two distinct EMT trajectories. Dysfunction of PRC2, but not KMT2D-COMPASS, yields a quasi-mesenchymal state that is associated with highly metastatic capabilities and poor survival of patients with breast cancer, suggesting that great caution should be applied when PRC2 inhibitors are evaluated clinically in certain patient cohorts. These observations identify epigenetic factors that regulate EMP, determine specific intermediate EMT states and, as a direct consequence, govern the metastatic ability of carcinoma cells.
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    PublicationOpen Access
    EPIKOL, a chromatin-focused CRISPR/Cas9-based screening platform, to identify cancer-specific epigenetic vulnerabilities
    (Nature Portfolio, 2022) Philpott, Martin; Cribbs, Adam P.; Kung, Sonia H.Y; Bayram, Özlem Yedier; Gökbayrak, Bengül; Kayabölen, Alişan; Aksu, Ali Cenk; Cavga, Ayşe Derya; Cingöz, Ahmet; Kala, Ezgi Yağmur; Karabıyık, Göktuğ; Esin, Beril; Morova, Tunç; Uyulur, Fırat; Önder, Tuğba Bağcı; Syed, Hamzah; Lack, Nathan Alan; Önder, Tamer Tevfik; PhD Student; Faculty Member; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; Graduate School of Health Sciences; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 184359; 318138; 120842; 42946
    Dysregulation of the epigenome due to alterations in chromatin modifier proteins commonly contribute to malignant transformation. To interrogate the roles of epigenetic modifiers in cancer cells, we generated an epigenome-wide CRISPR-Cas9 knockout library (EPIKOL) that targets a wide-range of epigenetic modifiers and their cofactors. We conducted eight screens in two different cancer types and showed that EPIKOL performs with high efficiency in terms of sgRNA distribution and depletion of essential genes. We discovered novel epigenetic modifiers that regulate triple-negative breast cancer (TNBC) and prostate cancer cell fitness. We confirmed the growth-regulatory functions of individual candidates, including SS18L2 and members of the NSL complex (KANSL2, KANSL3, KAT8) in TNBC cells. Overall, we show that EPIKOL, a focused sgRNA library targeting similar to 800 genes, can reveal epigenetic modifiers that are essential for cancer cell fitness under in vitro and in vivo conditions and enable the identification of novel anti-cancer targets. Due to its comprehensive epigenome-wide targets and relatively high number of sgRNAs per gene, EPIKOL will facilitate studies examining functional roles of epigenetic modifiers in a wide range of contexts, such as screens in primary cells, patient-derived xenografts as well as in vivo models.