Phd Degree / Doktora

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

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2015 - 20195

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End date: 2019Subject: search.filters.subject.Cancer cells

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Now showing 1 - 5 of 5
  • 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
    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
    Invetigation of Mechanical Vibration Effects on Breast Cancer Cells
    (Izmir Institute of Technology, 2018) Olçum Uzan, Melis; Özçivici, Engin; Erdal Bağrıyanık, Şerife Esra
    In this doctoral dissertation, low magnitude mechanical signals (LMMS, <1g in magnitude) were used to test the stress shielding model hypothesized on breast cancer cells. The hypothesis was that the breast cancer cells will be sensitive to mechanical vibrations and will respond to these vibrations. It was similarly used to test the adipogenic differentiation of Lamin A/C knockdown (by siRNA) bone marrow-derived mesenchymal stem cells. It is known that Lamin A/C plays a role in the nucleus and intracellular organization in these cells and affects gene expression by chromatin regulation. The hypothesis was that if these cells are deprived of the organization for the nucleus, they will be sensitive to mechanical vibrations, but that the mechanical vibrations cannot restore the effect of lamin A/C on gene regulation. We investigated the effects of high-frequency low-density mechanical signals (LMMS) on cell proliferation, apoptosis, cell cycle, protein expression, differentiation, cytoskeleton and phenotypic change processes. According to findings, LMMS caused cell cycle arrest in the aggressive type of breast cancer cells and slowed proliferation. Non-aggressive breast cancer has not responded to LMMS. In mammary epithelial cells, LMMS has not shown an effect that triggers proliferation. In the mesenchymal stem cell model, Lamin A/C knockdown accelerated adipogenic differentiation. Although LMMS in these cells decreased the rate of adipogenic differentiation, it was not sufficient to restore the baseline.
  • Doctoral Thesis
    Synthesis, Physicochemical Characterization, and Biosensing Applications of Gold Nanoparticles
    (Izmir Institute of Technology, 2018) Üçüncü, Melek; Özçelik, Serdar
    Cancer is one of the leading diseases that cause death all around the world. In Turkey, lung cancer is the most common type of cancer type in men and it is the fifth in women. Unfortunately, the percentage of treatment of lung cancer is too low. Gold nanoparticles (AuNPs) are widely used in the biotechnology as imaging, diagnosis, and therapeutic agents because of their unique properties such as plasmon resonance, easy synthesize, biocompatibility, and facile surface modification. In this study, it is aimed to design gold nanoparticles as biosensors for lung cancer cells. For this purpose, different sizes (5-40 nm) of Au nanoparticles were synthesized and their uptake and distribution into the lung cancer cells were investigated. The results of the study revealed that cellular uptake of gold nanoparticles are high for the size of 20 and 40 nm. The optimal visibility into the cells was achieved by using DIC microscopy in which the particles uptaken into the cytoplasm and localized at around nucleus of cells. In the second part of the study, surfaces of 20 and 40 nm particles were conjugated with RGD peptides and their distribution and light scattering properties were investigated in living cells by using dark-field microscopy. Due to the receptor-mediated endocytosis, RGD-AuNPs showed different distribution within the cells. These results indicate that the RGD conjugated Au nanoparticles exhibits much higher light scattering properties than non-conjugated nanoparticles. In addition to this, synthesized Au nanoparticles were conjugated with nucleus-localized peptide (NLS) and directed to the nucleus of cancerous (A549, H358) and healthy (BEAS2B) lung cells. The nucleus targeting properties of the NLS conjugated particles were also investigated to understand if there is any cell line selectivity. The internalizations of peptide conjugated Au nanoparticles into cell lines were visualized in living cells by using DIC microscopy. NLS conjugated AuNPs internalized into nucleus of A549 and H358 cancer cells. Although NLS conjugated AuNPs present inside the cytoplasm of BEAS2B cells, they did not localize into the nucleus of normal cell lines.
  • Doctoral Thesis
    The Investigation of Anticancer Properties of (r)-4'-methylklavuzon in Liver Cancer Cells and Liver Cancer Stem Cells
    (Izmir Institute of Technology, 2017) Delman, Murat; Çağır, Ali; Erdal, Esra
    Hepatocellular carcinoma (HCC) is the fifth most seen cancer type and the third leading cause of death from cancers. HCC is a fatal disease and HCC patients have a 5-year survival rate of 14%. Discovery and identification of mechanisms of action for new therapeutic agents are required for a better treatment of HCC. One of the most important target in cancer treatment is the epigenetic acetylation of histones. Histone deacetylases (HDAC) and sirtuins provide chromatin compaction and transcriptional repression by removing acetyl groups from histone proteins and nonhistone proteins. Re-acetylation of chromatin and re-expression of tumor suppressor genes with the discovery of novel HDAC and/or sirtuin inhibitors are therapeutic targets in cancer research. In this study, (R)-4’-methylklavuzon was found to be cytotoxic in HuH-7 cells with IC50 values of 1.25 μM for HuH-7 parental cells, 2.5 μM for EpCAM+/CD133+ HuH-7 cells and 1.25 μM for EpCAM-/CD133- HuH-7 cells. It was observed that (R)-4’-methylklavuzon causes cell cycle arrest at G1 phase at 1.00 μM concentration in three cell populations, it induces apoptosis at 10 μM concentration at the end of 24 hours incubation. (R)-4’-methylklavuzon does not inhibit Class I/II HDACs in vitro whereas it causes inhibition of endogenous HDACs and/or sirtuins inside the cells sorted by MACS and FACS at 0.10 μM concentration. (R)-4’-methylklavuzon upregulates p21 expression significantly in HuH-7 cell populations to cause G1 arrest. It causes 45% inhibition in p53/MDM2 complex formation when examined with pure p53 and MDM2 proteins. Drug candidate causes 46% SIRT1 inhibition at 100 μM concentration in vitro whereas there was no inhibition of HDAC1 enzyme at the same concentration. SIRT1 protein levels in HuH-7 parental cells were upregulated to 240% within 24 hours of incubation with 3.00 μM of drug candidate. It was found that (R)-4’-methylklavuzon can also inhibit CRM1 protein providing increased retention of tumor suppressor proteins in the nucleus. p53 was overexpressed at 0.10 and 1.00 μM concentrations within 6 and 24 hours in HepG2 cells but slightly overexpressed in HuH-7 parental 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; Baran, Yusuf
    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.