Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
10 results
Search Results
Master Thesis Optimization of a Liver Organ on Chip System for the Investigation of Breast Cancer Cell Invasion(01. Izmir Institute of Technology, 2023) Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThere are many challenges in creating an accurate and physiologically relevant three-dimensional (3D) model of the liver such as finding the suitable liver extracellular matrix (ECM) components and cell types for the development of cell-laden liver-on-a-chip systems. In recent years, precision tissue slice-based methods are used to reduce the problems caused by the cell-laden liver-on-a-chip system complexity. However, these methods require sophisticated tools which are not easily accessible. This study focuses on the development of a 3D liver model using simple and cost-effective methods. To achieve this, we aimed to optimize liver tissue size, maintenance and culture medium, scaffold gel, and viability assay. The needle method was found to be the easiest, most efficient, and cheap method for tissue processing as the equipment used was easily accessible and evaded enzymatic steps. Moreover, consistent samples that were all similar and in the desired size were easy to obtain. In addition to these, functionality and viability were analysed for 72 hours to assess the physiological state of the liver after tissue processing. Based on these findings a novel liver-on-a-chip system was successfully developed and as the next step, the invasion of the MDA-MB-231 breast cancer cell line towards the liver was investigated with and without the presence of C-X-C chemokine receptor type 4 (CXCR4) antagonists AMD3100 and AMD3465. In conclusion, this study demonstrated the development of a novel 3D model for the liver and provided a platform for studying breast cancer invasion with its potential implications for cancer therapy research.Master Thesis Role of Human Aprataxin Protein in P53-Related Cellular Processes in Breast Cells(01. Izmir Institute of Technology, 2021) Doğan, Hülya; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 01. Izmir Institute of Technology; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of ScienceAprataxin encoded by APTX, which is the human homolog of yeast HNT3, reverses adenylation damages emerged from abortive DNA ligation during ribonucleotide and base excision repair. Thus, it corrects AMP-modified nucleic acid termini and protects genome integrity as a DNA ligase "proofreader". Role of HNT3, which is a candidate p53-related gene, against DNA oxidative and alkylating damage indicates its antioxidant importance. Besides, previous studies demonstrated that absence of Aprataxin gives rise to ROS generation and oxidative stress in addition to mitochondrial dysfunction. Also, role of Aprataxin in drug and radiotherapy sensitivity was shown in many cancer. Since conformation of cysteine residues in p53 DNA-binding domain can be modified by oxidizing environment, functionality can be influenced by defective APTX. Although p53-Aprataxin interaction has been shown by co-immunoprecipitation, effects of APTX on p53 pathway were not studied. Aim of this study is to investigate Aprataxin-driven changes in p53-regulated processes in p53 wild-type cells through. According to results, Aprataxin overexpression leads to cell cycle arrest in low stress levels. However, it triggers cell death against induced stress in MCF10A cells. Moreover, apoptotic assay on MCF10A APTX Crispr cells indicated elevated level of basal cell death. Also, expression analysis of p53 targets in APTX knockdown MCF7 cells revealed that extrinsic apoptosis pathway might be induced. Consequently, these results help us to gain insight into how Aprataxin affects activity of p53 pathway. Further investigation providing stress accumulation based assays and protein level analysis is needed to figure out whether resulting changes are p53-dependent or not.Master Thesis Investigating the Effect of Human Sacm1l Gene in the P53 Wild Type Breast Epithelial Mcf10a and Breast Cancer Mcf7 Cells(01. Izmir Institute of Technology, 2021) Efe, Eda; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 01. Izmir Institute of Technology; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Sciencep53, tumor suppressor protein, plays role in the regulation of many cellular processes. Thus, p53 activity is controlled by a series of mechanisms, one of which is a redox reaction. However, redox regulation of p53 is not well defined in the literature. As a candidate of antioxidant, Sac1 gene mutation resulted in decreased levels of human p53 protein in transformed yeast, but the human homolog of Sac1 (SACM1L) has not been studied yet. SACM1L is known to function as a phosphoinositide phosphatase, hydrolyzes PI4P in the Golgi and ER. Previous studies demonstrated SACM1L depletion in HeLa cells led to decreased viability and arrest at the G2/M phase. However, no data were found on the association between the SACM1L and either directly p53 or p53 mediated cellular processes. We aimed to investigate the role of SACM1L in p53 controlled cellular processes like cell cycle and apoptosis in p53 wild type (wt) breast epithelial cells MCF10A and breast cancer cells MCF7 in the presence or absence of SACM1L gene. We demonstrated that SACM1L knockout MCF7 cells were arrested in the G1 phase, and number of proliferating cells was reduced, whereas overexpression of SACM1L did not change the proliferation, and cell cycle. Further, the rate of apoptosis was increased in SACM1L overexpressing and knockout MCF10A and MCF7 cells, supported by the findings of transcriptional analysis for p53 target genes. In conclusion, the greatest effect of SACM1L was observed in the apoptosis, but the underlying mechanisms are still unclear and must be further studied.Master Thesis Investigating Oncogenic Role of Sema6d in Breast Cancer Cells(Izmir Institute of Technology, 2019) Günyüz, Zehra Elif; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyBreast cancer, the most commonly diagnosed cancer type and the leading cause of cancer-associated deaths, is the major health issue among women worldwide. In many cancer types, the expression of the semaphorins and their receptors such as plexins and neuropilins are dysregulated. SEMA6D is a member of class-6 family transmembrane semaphorin proteins and acts through Plexin-A1 receptor. It was previously shown that overexpression of SEMA6D in breast cancer cell line MCF-7 leads to a reduction in proliferation and an increase in migration. On the other hand, in the MDA-MB-231 breast cancer cell line, overexpression of SEMA6D had no significant effect on proliferation but enhanced migration. In this study, we aimed to analyze the effects of SEMA6D overexpression in normal breast cell line MCF10A and investigate the invasive behavior and transformation capacity of SEMA6D overexpressing breast cancer cell lines. We demonstrated that overexpression of SEMA6D leads to elevated proliferation, viability and migration in MCF10A cells, whereas it did not trigger their anchorage-independent growth. On the other hand, MDA-MB-231 and MCF7 cells stably expressing SEMA6D showed reduced colony formation in the soft-agar assay. Furthermore, the invasiveness of MDA-MB-231 cells was elevated with SEMA6D overexpression, whereas SEMA6D overexpression did not stimulate the invasiveness of MCF-7 cells through matrigel microenvironment, whereas slightly trigger invasion through bone microenvironment. In conclusion, SEMA6D overexpression has cell-specific effects on breast cancer. The exact role of SEMA6D in breast cancer development remains undefined and must be further investigated.Master Thesis Cyr61-Notch Interaction During Epithelial-To Transition, Migration and Invasion in Breast Cancer Cells(Izmir Institute of Technology, 2017) İlhan, Mustafa; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyNotch signaling is one of the major pathways involved in development and tumorigenesis. Activated Notch is correlated with increased migration, invasion and epithelial-to-mesenchymal-transition (EMT) in breast cancer. However, mechanism of Notch-mediated cancer progression is poorly understood. CYR61 is a secreted protein and its upregulation is also related to increased breast tumorigenesis and EMT. Microarray analyses revealed that CYR61 was differentially expressed in response to Notch activation in breast epithelial cells. We hypothesized that CYR61 is a downstream mediator of Notch during EMT, migration and invasion. To test whether Notch requires CYR61 during EMT, migration and invasion, two complementary approaches were followed: (i) CYR61 expression was silenced by using shRNA in MCF10A epithelial breast cell line in the presence of Notch activation, (ii) CYR61 was over-expressed in MDA-MB-231 cancer breast cell line in the absence of Notch activity. Then, expression of EMT markers was analyzed in mRNA and protein levels via RT-qPCR and immuno-blotting, respectively. Migration and invasion ability of cells were investigated by wound healing assay and a lab-on-a-chip-system, respectively. Here, it was shown that CYR61 inhibition decreased Notch-induced EMT, migration and invasion of MCF10A and CYR61 overexpression in the absence of Notch activity partially rescued Notch-mediated invasion in MDA-MB-231 cell lines. Our findings suggest that CYR61 may act in downstream of Notch and is regulated by Notch. When we consider importance of CYR61 in Notch-induced EMT and cancer progression, targeting CYR61 may hold promise to develop novel strategies for treatment of breast cancer in early stages.Master Thesis Role of Sema6d in Proliferation, Epithelial-Mesenchymal Transition and Migration of Breast Cancer Cell Lines(Izmir Institute of Technology, 2017) Şahi, Ece; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyBreast cancer is one of the most common cancer types around world and the second leading cause of cancer related deaths among women. Not the primary tumor but distant metastases are mainly the reason of deaths. For metastasis, the cells may go through epithelial-mesenchymal transition (EMT), and acquire migration and invasion abilities. SEMA6D is a transmembrane protein that belongs to a large semaphorin family. SEMA6D is involved in the migration of embryonic cardiac cells. Recently it was validated as an oncogene in osteosarcoma. Also, its oncogenic roles were investigated in gastric cancer and mesothelioma. According to in silico analysis of the Cancer Genome Atlas (TCGA), high SEMA6D expression level is associated with better survival of triple negative breast cancer patients. However, there is not any published study which investigates roles of SEMA6D in breast cancer yet, other than bioinformatic analysis. Therefore, we aimed to understand role of SEMA6D in proliferation, EMT and migration of breast cancer cells. We observed that overexpression of SEMA6D reduces proliferation but enhances migration in non-invasive breast cancer cell line MCF7. Thereby, SEMA6D may increase metastatic ability of MCF7 cells. Its metastatic ability was also supported by changes in EMT markers. On the other hand, proliferation of metastatic breast cancer cell line MDAMB231 was not significantly changed by overexpression of SEMA6D and migration ability was slightly reduced but mesenchymal markers tended to increase in SEMA6D overexpressing MDAMB231 cells. As a conclusion, SEMA6D tends to enhance proliferation, migration through EMT in MCF7 cell line whereas overexpression of SEMA6D did not demonstrate significant effect on metastatic MDA-MB-231 cell line. Therefore, we should separately evaluate role of SEMA6D in different breast cancer cell lines and further studies are required to understand role of SEMA6D in breast cancer.Master Thesis Identification of Novel Notch Target Genes That Are Mediators of Notch in Inducing Epithelial To Mesenchymal Transition and Migration/Invasion(Izmir Institute of Technology, 2016) Küçükköse, Cansu; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyNotch signaling has first been described in murine mammary gland by the proviral integration of mouse mammary tumor virus (MMTV) into the Notch4 locus (Int3 locus) which resulted expression of constitutively active form of Notch4 and transformation of mammary epithelial cells. Notch1 is highly expressed in breast cancer and constitutively active form of Notch1 induces neoplasm. In breast cancer, overexpression of active Notch1 receptor (NICD) promotes epithelial-mesenchymal transition (EMT) via Snail induction which demonstrates the role of Notch signaling in induction of metastasis through EMT. However, the downstream mediators of Notch in EMT, migration and invasion processes are still elusive. In this study, we hypothesized that Notch signaling induces EMT and migration via regulating one or more of the seven candidate genes that are SEMA6D, SEMA3C, CXCR7, CXCL14, CCL20, HMGA2 and CYR61 which were shown to be differentially regulated by Notch signaling in breast cells in microarray data. The candidate genes are involved in EMT and migration in different cell types and tissues. We showed that Notch1 activation in normal breast epithelial cell line MCF10A significantly increased both mRNA and protein expressions of SEMA6D and CYR61 while it significantly reduced SEMA3C and HMGA2 mRNA levels. Notch inhibition led to significant reduction in mRNA expression of CYR61, CCL20 and HMGA2 and protein expression of CYR61 only, while the rest of candidate genes were affected slightly in breast cancer cell line, MDA-MB-231. We chose SEMA6D for further investigation because there is no data indicating the role of SEMA6D in breast cancer in the literature. SEMA6D could be mediator of Notch signaling to induce EMT because it partially rescues negative effect of Notch inhibition on EMT markers. Notch independent effect of SEMA6D suggested that SEMA6D may be involved in inhibiting EMT whereas, it induced migration and cell viability in MDA-MB-231 cell line.Further analysis is required to reveal the role of SEMA6D in EMT and migration.Master Thesis Role of Irf6 in Notch Regulated Apoptosis, Cell Cycle and Differentiation in Breast Epithelial Cells(Izmir Institute of Technology, 2015) Ekinci, Burcu; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyNotch pathway, an evolutionarily conserved signaling, controls development, differentiation and proliferation. Notch1 and Notch4 activation caused mammary tumor formation showing an oncogenic effect. Overexpression of Notch1 can also supress proliferation in breast epithelial cells depending on dosage and cell type. Thus, Notch can act as an oncogene or tumor suppressor in breast. IRF6, a member of interferon regulatory factor family, has a role in development and differentiation of the epidermis, downstream of Notch signaling. IRF6 overexpression induces cell cycle arrest in breast cancer cells showing a tumor suppressor role. It was recently identified that IRF6 is a mediator of Notch in proliferation and transformation of breast epithelial cells. In this study, it was aimed to identify whether IRF6 has any effect on cell cycle regulation, apoptosis and breast cancer stem cell population (BCSCs) under Notch and whether IRF6 has a role in expression of luminal and basal markers in breast cell lines. Our results showed that IRF6 knockdown in normal breast epithelial cell line, MCF10A, reduced percentage of cells in S-phase, which was increased by Notch activation. IRF6 knockdown induced early apoptosis and reduced BCSCs, however it has no effect downstream of Notch in these processes. On the other hand, IRF6 did not play an essential role on expression of luminal and basal markers. In conclusion, our previous observation was supported that IRF6 is a mediator of Notch in cell proliferation. Furthermore, these data showed that IRF6 has a novel role on early apoptosis and stem cell population independent of Notch signaling.Master Thesis Molecular Characterization of Adult Stem Cells' Adaptations To Mechanical Signals During Adipogenic Commitment(Izmir Institute of Technology, 2015) Özçivici, Engin; Baskan, Öznur; Baskan, Öznur; Yalçın Özuysal, Özden; Özçivici, Engin; Yalçın, Özden; 03.01. Department of Bioengineering; 01. Izmir Institute of Technology; 04.03. Department of Molecular Biology and Genetics; 03. Faculty of Engineering; 04. Faculty of SciencePrevalence of obesity have increased across the years based on technological developments that supported nutritional availability and sedentary lifestyles. Restoring mechanical activity with physical exercise suppresses obesity, and mechanical loading can also be delivered passively with whole body vibrations with high frequency and low magnitude. Anabolic effects of high frequency low magnitude mechanical vibrations on adult stem cells are well identified whereas sensing mechanism of cells and their response to mechanical stimuli is largely unknown. Here, we hypothesed that daily bouts of low intensity vibrations will affect molecular, physical and ultrastructural profile of the cells and the effect will interact with the adipogenic induction. To test this hypothesis mouse bone marrow stem cell line D1 ORL UVA were subjected to mechanical vibrations (0.15g, 90 Hz, 15min/d) for 7 days to both during quiescence and adipogenic commitment. Ultrastructural changes were identified on cellular and molecular levels. Atomic force microscopy was used to characterize the changes on cell surface and significant increase was observed in cell surface height. Moreover, in order to identify the changes in cytoskeleton structure and physical properties, actin were stained with phalloidin and imaged with inverted microscope. To quantify phalloidin amount, signal intensities and physical features of the cells were measured. It was observed that mechanical stimulation and adipogenic induction affect actin content and the physical structure of the cells significantly. Molecular level analysis of cytoskeleton elements and adipogenic markers were performed with Real time PCR. Dramatic increases in adipogenic markers were detected with adipogenic induction. These results indicate that mesenchymal stem cells responds to mechanical vibrations by altering their molecular and ultrastructure during both quiescence and adipogenesis.Master Thesis Role of Irf6 as a Mediator of Notch Signaling in Breast Cancer Cell Lines(Izmir Institute of Technology, 2014) Zengin, Talip; Yalçın Özuysal, Özden; Yalçın Özuysal, Özden; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyNotch signaling is an evolutionary conserved pathway involved in development and differentiation. Disregulated Notch signaling is involved in cancer by showing tumor supressor or oncogenic properties. Notch signaling has firstly been described in breast cancer by the activation of Notch4 locus. Expression of a constitutively active form of Notch1 induces neoplasms and high level expression of Notch1 is observed in human breast cancer which indicate that Notch is an oncogene in breast tissue. However, recently it has been shown that Notch activation can decrease cell proliferation in human breast epithelial cells. The downstream mechanisms of Notch signaling that elicit oncogenic or tumor suppressor roles remain elusive. IRF6, a member of interferon regulatory factors, has been characterised as a novel Notch target gene involved in keratinocyte differentiation. IRF6 has been stated as a potential tumor suppressor in collaboration with Maspin in mammary epithelial cells. In this project, it was investigated whether IRF6 expression is regulated by Notch signaling in breast epithelial cells and whether it is a mediator of Notch in cell proliferation and transformation. It was shown that activation of Notch signaling in normal breast epithelial cell line MCF10A, increased expression of IRF6, while inhibition of Notch signaling in breast cancer cell line MDA-MB-231 reduced IRF6 levels. IRF6 silencing reduced Notch induced cell transformation in MCF10A cells but did not result in significant change in proliferation. These results indicate that IRF6 is a downstream target of Notch and functions as a mediator for Notch signaling in breast epithelial cells.