Phd Degree / Doktora

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

Browse

Filters

2018 - 201912020 - 20225

Settings

Access Right: Open AccessSubject: search.filters.subject.Breast cancer

Search Results

Now showing 1 - 6 of 6
  • Doctoral Thesis
    Investigating Molecular Mechanisms Underlying Resistance To Notch Inhibitors in Breast and Ovarian Cancer
    (2022) Telli, Kübra; Yalçın Özuysal, Özden
    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
    Multi-organ-on-a-chip for cancer drug testing
    (Izmir Institute of Technology, 2022) Mohammed, Abdurehman Eshete; Pesen Okvur, Devrim; Erdal Bağrıyanık, Şerife Esra
    Cancer is one of the devastating and fatal severe diseases worldwide that kills millions of people every year. Globally cancer is the second leading cause of death after cardiovascular disease and was responsible for 10 million deaths in 2020. Breast cancer is one of the predominant cancers in females and is the cause of more than half a million females death each year. The primary cause of cancer patients' death is cancer metastasis. Triple-negative BREAST cancer (TNBC) is mainly treated by chemotherapy. In the current drug discovery and development processes, the efficacy and toxicity of chemotherapies identify using 2D and animal testing but not simulating the in vivo microenvironment. This research designed multiorgan-on-a-chip with liver and breast cell line compartments, and drug PKPD modeling was done by Monolix software. In this research, a unique multiorgan-on-a-chip (MOC) was designed and fabricated, generated experimental PK and PD data using the new MOC device, and modeled and simulated PK and PD using the experimental data. To conclude, we developed a new multiorgan-on-a-chip (MOC) platform used for PKPD modeling and PKPD simulations that would be helpful in the preclinical research to evaluate the effectiveness and toxicity of drugs. In the future, using calceinAM, a fluorescent cell viability dye, generating PD data for each cell type and determining side effects of doxorubicin in each cell line is essential. Adding more organs to the MOC, such as heart tissue, to study the cytotoxicity of doxorubicin in different organs gives more efficient data for PKPD modeling.
  • Doctoral Thesis
    Detection of the Metastatic Potential of Breast Cancer Cell Lines To Specific Target Tissues
    (01. Izmir Institute of Technology, 2021) Fıratlıgil Yıldırır, Burcu; Yalçın Özuysal, Özden
    Breast cancer is one of the most frequently diagnosed cancer types and the second leading cause of cancer-associated deaths in women. Breast cancer begins as a local disease which can then metastasize to distant sites specifically to bone, lung and liver. The increasing rate of the metastasis-related deaths asserts the need to develop in vitro diagnostic strategies representing in vivo properties better. In this study, two different lab-on-a-chip (LOC) platforms, IC- and EX-chips, were used to detect the invasion and extravasation potentials, respectively, of breast cancer cells to 3D in vitro generated bone, lung, liver and breast microenvironments. The metastatic MDAMB231, but not non-metastatic MCF7 breast cancer cells showed higher invasion and extravasation potentials towards lung and liver microenvironments than breast microenvironment. Lung-specific but not bone-specific metastatic subclonal cells invaded significantly towards lung microenvironment. On the other hand, an intensive invasion was observed in bone-specific but not lung-specific metastatic subclonal cells towards bone microenvironment demonstrating different in vivo metastatic behaviors of breast cancer cells. Overall, the tissue-specific invasion and extravasation capacities of breast cancer cells were demonstrated with IC- and EX-chips where the physiologically more relevant bone, lung, liver and breast homing target sites were generated by a specific emphasis on ECM components, stromal cells and secreted factors. This study is important in providing a basis for the development of diagnostic tools and precision therapeutics for breast cancer metastasis.
  • Doctoral Thesis
    Engineering Target Tissue in Lab-On Devices for Predicting Homing Choices of Metastatic Cancer
    (Izmir Institute of Technology, 2020) Batı Ayaz, Gizem; Pesen Okvur, Devrim; Yavuz, Oktay
    The metastatic cascade of cancer results in the extravasation of the tumor to other parts of the body. Metastasis is the leading cause of cancer related deaths. Breast cancer is the most common cancer in women, and lung is one of the organs with the most metastasis. For this reason, it is critical to engineer a tissue microenvironment that includes complex cell-cell interactions with co-culture of endothelial, epithelial and stromal cells, and the invasion and extravasation steps of metastasis can be observed for early diagnosis of metastasis. Vascularization is the critical step for engineering the tissues. The in vitro models used today are insufficient to create the tissue environment closest to in vivo conditions. Recently developed lab-on-a-chip platforms provide suitable environments for mimicking the in vivo structure in tissue engineering studies. In this research: -Different lab-on-a-chip devices fabricated to engineer breast and lung target tissues. -For the first time, epithelial, fibroblast and endothelial cells were tri-cultured and breast and lung tissue environments were engineering with microvasculature. -Different gel, media and cell numbers have been optimized for engineering of breast and lung tissue environments with microvascularization. -Different matrix environments have been optimized to observe invasion and/or extravasation steps separately or together.
  • Doctoral Thesis
    Investigating the Role of Connexin 32 in Breast Cancer
    (Izmir Institute of Technology, 2020) Uğur, Deniz; Meşe Özçivici, Gülistan
    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
    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.