Phd Degree / Doktora

Permanent URI for this collectionhttps://hdl.handle.net/11147/2869

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Department: search.filters.department.Thesis (Doctoral)--İzmir Institute of Technology, Molecular Biology and GeneticsSubject: search.filters.subject.Cancer cells

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Now showing 1 - 4 of 4
  • Doctoral Thesis
    Investigating Molecular Mechanisms Underlying Resistance To Notch Inhibitors in Breast and Ovarian Cancer
    (2022) Telli, Kübra; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Breast and ovarian cancers remain highly malignant among women with more than 11% overall of incidence rates worldwide. Traditional treatment strategies including chemotherapy, radiotherapy and hormone therapies continues to be successful yet for the long-term, cancer recurrence and drug resistance remains to be the main issue. In addition to the altering common cell fate regulations, cancer cells modify signaling pathways to overcome cytotoxicity. Notch signalling pathway is a conserved ligand-receptor pathway that necessarily plays role in survival homeostasis, yet it is dysregulated in various cancers. Currently, novel treatment strategies are targeting this pathway through Gamma Secretase Inhibitors (GSI) DAPT, R04929097 and MK0752 that are use both as a single agent and in combinations with Docetaxel or Cisplatin. The clinical success of these inhibitors requires further examination of potential intrinsic or acquired resistance profiles. In this study, we generated breast cancer cells (MDA-MB-231 and MCF-7) resistant to DAPT or R04929097 and ovarian cancer cells (IGROV-1, BG-1, SKOV-3 and A2780) resistant to MK0752 by gradual treatments of increasing doses based on drugs’ IC50 values. Morphological changes, growth rates, migration alterations, mRNA expressions of Notch pathway components and epithelial mesenchymal transition markers, 3D setups for acidosis responses and protein expressions for c-myc and oxidative stress response markers were analyzed. Furthermore, proteomic analysis was carried out with the ovarian cancer cell line IGROV-1. The response of the cells to different drug treatments and dysregulated protein families exposed in resistance mechanisms behind DAPT, R04929097 and MK0752 for both breast and ovarian cancer cells are reported. Overall, this study reveals possible resistance mechanisms against GSIs and emphasizes potential targets through well-known hallmarks of cancer drug resistance.
  • Doctoral Thesis
    Investigating the Role of Connexin 32 in Breast Cancer
    (Izmir Institute of Technology, 2020) Meşe Özçivici, Gülistan; Uğur, Deniz; Meşe Özçivici, Gülistan; 04.03. Department of Molecular Biology and Genetics; 01. Izmir Institute of Technology; 04. Faculty of Science
    Connexins (Cx) are primary components of gap junctions, selectively allowing molecules to be exchanged between adjacent cells. Along with their channel forming functions, connexins play variety of roles in different stages in tumorigenesis, both dependent and independent of gap junctions in connexin and cancer dependent manner. Cytoplasmic accumulation of Cx32 was shown in some breast cancers; and compared to the primary tumors Cx32 is further upregulated in metastasis. However, the complete picture for the role of Cx32 in breast cancer remains to be elusive. Through overexpressing Cx32, its functions in breast cancer cells were investigated in Hs578T and MCF7 breast cancer cells. Cx32 overexpression increased cellular proliferation with significant increase in S phase in Hs578T cells with no significant change on MCF7 cells. Cx32 overexpression did not induce hemichannel activity in neither cell; it reduced gap junctional functions in Hs578T cells. Cx32 in both cells localized in cytoplasm did not form intercellular plaques, and decreased Cx43 expression. Cx32 overexpression reduced the migration and invasion capacity in both cells and in Hs578T cells showed reduction of mesenchymal and increase of epithelial marker expressions. In conclusion, Cx32 increases proliferation and decreases communication in Hs578T cells while not affecting MCF7 cells. It decreases aggressiveness and metastatic potential for both cell lines. Due to changes in gap junctional functions, Cx32 might be acting in relation to GJIC in Hs578T cells and outside of it in MCF7 cells. All in all, presence of Cx32 made Hs578T cells act similar to endogenously Cx32 expressing MCF7 cells.
  • Doctoral Thesis
    Sensitization of Philadelphia Positive Acute Lymphoblastic Leukemia Cells Resistant To Imatinib by Targeting Sphingolipid Metabolism
    (Izmir Institute of Technology, 2019) Kiraz, Yağmur; Baran, Yusuf; Kiraz, Yağmur; Baran, Yusuf; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Philadelphia positive acute lymphoblastic leukemia (Ph+ALL) is a common subtype of ALL and characterized by having BCR/ABL translocation. Tyrosine kinase inhibitors (TKI) such as imatinib are used for the treatment in Ph+ALL, however, 60-75% of the patients can develop resistance against the TKIs. Bioactive sphingolipids are a group of lipids that play roles in various cellular mechanisms. Previous studies showed that sphingolipids and genes in the pathway were involved in response to TKI treatment in Ph+ALL. Here, we investigated the roles of SPL on the growth inhibitory effects of imatinib and exploit sphingolipid metabolism by majorly inhibiting glucosylceramide synthase (GCS) to accumulate ceramide or sphingosine to further sensitize cells to imatinib and/or overcome resistance to imatinib in Ph+ALL. Firstly, we detected that, sphingosine kinase-1 (SK-1) a well-studied SPL enzyme inhibition did not contribute to cytotoxic effects of imatinib in SD-1 Ph+ALL cells. Moreover, we determined that imatinib is inducing de novo synthesis pathway of SPL and increasing the levels of ceramide, sphingosine, hexosylceramides and sphingomyelin in SD-1 cells. Interestingly, newly generated imatinib-resistant cell line SD-1R was detected to have an aberration in this pathway resulting in development of resistance. Combination treatment with eliglustat (GCS inhibitor) resulted in a significant increase in ceramide and sphingosine levels and reflected on cell growth and sensitized cells to imatinib. Taken together, it was shown for the first time in the literature that the cytotoxic effects of imatinib was due to induction of de novo synthesis pathway of sphingolipids and inhibition of GCS together with imatinib has synergistic cytotoxic effects on imatinib resistant Ph+ALL cells. As a conclusion, increasing the intracellular levels of ceramide (and/or sphingosine) can be a novel approach to sensitize drug resistant Ph+ALL cells.
  • Doctoral Thesis
    Therapeutic Potentials of Fisetin, Hesperetin and Vitexin on Chronic Myeloid Leukemia and Acute Myeloid Leukemia Cells
    (Izmir Institute of Technology, 2015) Adan Gökbulut, Aysun; Adan Gökbulut, Aysun; Baran, Yusuf; Baran, Yusuf; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Fisetin, hesperetin and vitexin are plant-derived flavonoids. This thesis study aims to investigate therapeutic potentials of them on human HL60 APL and K562 CML cells since there are no studies on these cells. The effects of these compounds on APL and CML cells have been considered in terms of cytotoxicity, apoptosis and cell cycle progression. In this study, genome-wide microarray analysis has been also performed for APL and CML cells to identify the genes and networks that are responsible for fisetin and hesperetin-induced effects. In summary, we intented to explain the molecular mechanisms and global gene expression patterns related with the effects of these flavonoids on both APL and CML for the first time. There were decreases in the viability/proliferation of K562 and HL60 cells treated with fisetin, hesperetin and vitexin. Fisetin was the most effective flavonoid for the induction of apoptosis in both cells. Fisetin, hesperetin and vitexin have been found to affect cell cycle progression at different phases of the cell cycle in both CML and AML cells, thus having cytostatic effects. In conclusion, the results of this study indicated that especially fisetin and hesperetin may have therapeutic potential in APL and CML cells due to induction of apoptosis, inhibition of cell proliferation and cell cyle arrest. Moreover, the genetic networks derived from this study illuminate some of the biological pathways affected by fisetin and hesperetin treatment while providing a proof of principle for identifying candidate genes that might be targeted for CML and APL therapy.