Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 6Citation - Scopus: 6A Molecular and Biophysical Comparison of Macromolecular Changes in Imatinib-Sensitive and Imatinib-Resistant K562 Cells Exposed To Ponatinib(SAGE Publications Inc., 2016) Kartal Yandım, Melis; Ceylan, Çağatay; Elmas, Efe; Baran, YusufChronic myeloid leukemia (CML) is a type of hematological malignancy that is characterized by the generation of Philadelphia chromosome encoding BCR/ABL oncoprotein. Tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, and dasatinib, are used for the frontline therapy of CML. Development of resistance against these TKIs in the patients bearing T315I mutation is a major obstacle in CML therapy. Ponatinib, the third-generation TKI, is novel drug that is effective even in CML patients with T315I mutation. The exact mechanism of ponatinib in CML has been still unknown. In this study, we aimed to determine the potential mechanisms and structural metabolic changes activated by ponatinib treatment in imatinib-sensitive K562 human CML cell lines and 3 μM-imatinib-resistant K562/IMA3 CML cell lines generated at our lab. Apoptotic and antiproliferative effects of ponatinib on imatinib-sensitive and 3 μM-imatinib-resistant K562/IMA3 CML cells were determined by proliferation and apoptosis assays. Additionally, the effects of ponatinib on macromolecules and lipid profiles were also analyzed using Fourier transform infrared spectroscopy (FTIR). Our results revealed that ponatinib inhibited cell proliferation and induced apoptosis as determined by loss of mitochondrial membrane potential, increased caspase-3 enzyme activity, and transfer of phosphatidylserine to the plasma membrane in both K562 and K562/IMA-3 cells. Furthermore, cell cycle analyses revealed that ponatinib arrested K562 and K562/IMA-3 cells at G1 phase. Moreover, ponatinib treatment created a more ordered nucleic acid structure in the resistant cells. Although the lipid to protein ratio increased in imatinib-sensitive K562 cells with a little decrease in the K562/IMA-3 cells, ponatinib treatment indicated significant changes in the lipid composition such as a significant increase in the cellular cholesterol amounts much more in the K562/IMA-3 cells than the sensitive counterparts. Unsaturation in lipids was higher in the resistant cells; however, increases in lipids without phosphate and the number of acyl chains were much higher in the K562 cells. Taken together, all these results showed powerful antiproliferative and apoptotic effects of ponatinib in both imatinib-sensitive and imatinib-resistant CML cells in a dose-dependent manner, and hence, the use of ponatinib for the treatment of TKI-resistant CML patients may be an effective treatment approach in the clinic. More importantly, these results showed that FTIR spectroscopy can detect drug-induced physiological changes in cancer drug resistance.Article Citation - WoS: 11Citation - Scopus: 9Biophysical Evaluation of Physiological Effects of Gilthead Sea Bream (sparus Aurata) Farming Using Ftir Spectroscopy(Elsevier Ltd., 2014) Ceylan, Çağatay; Tanrıkul, Tansel; Özgener, HüseyinSparus aurata is one of the two most important cultured fish species in the Mediterranean region. The present work investigates the effects of culturing in S. aurata liver tissue at the molecular level using Fourier Transform Infrared (FTIR) spectroscopy. FTIR spectroscopy revealed dramatic differences between the wild and aquacultured fish liver cells, which mainly indicated that the level of glycogen increased in the aquacultured samples and the protein/lipid ratio decreased by 42.29% indicating that triglycerides and cholesterol esters increased and the protein content decreased in the aquacultured samples. The 15.99% increase in the level of unsaturation indicated elevated lipid peroxidation. Structural/organisational changes in the nucleic acids along with increased transcriptional status of the liver tissue cells were observed in the cultured fish tissue. All these results indicated that culturing induces significant changes in fish physiology. In addition FTIR spectroscopy is a promising method to monitor the physiological changes in fish physiology.Article Citation - WoS: 1Citation - Scopus: 2Structural and Functional Characterization of Solution, Gel, and Aggregated Forms of Trypsin in Organic Solvent-Assisted and Ph-Induced Phase Changes(Türk Biyokimya Derneği, 2015) Ceylan, Çağatay; Karaçiçek, BilgeIn this study the effect of three different physicochemical parameters on pHtriggered gelation and aggregation of bovine pancreatic trypsin changes and structural and functional changes in these changes in alcohol-water mixtures were studied. Methods: Trypsin gelation times were studied using inverted tube method. Trypsin stability was studied using trypsin enzyme assay. Protein secondary structural changes were monitored using FTIR spectroscopy. Gel and aggregate macrostructures and morphologies were viewed using Scanning Electron Microscopy. Results: The solution phase was observed in the absence of both NaOH and CaCl2. The gel phase was observed in the absence of the either. The aggregate phase was observed in the presence of the both agents all depending on trypsin concentrations used. Trypsin stability studies showed that there were a nearly 53 and 32% specific activity losses after the gelation and aggregation processes. According to FTIR studies β–sheet structure in 1637 cm-1 band disappeared in trypsin gel and trypsin aggregates. Increases in α–helix structure in 1651 cm-1 in trypsin gel and aggregates were observed. Iodoacetamide delayed the gelation and prevented the aggregation indicating the importance of intermolecular disulfides in the both processes. Conclusion: Trypsin gelation was caused by the denaturation of the protein three dimensional structures. The gel and aggregate formation indicates a secondary structural change towards α–helix structure formation at the expense of β–sheet structure and formation of intermolecular disulfide bonds.Article Citation - WoS: 3Citation - Scopus: 3Evaluation of High Hydrostatic Pressure Effects on Bovine Red Blood Cells and Platelets(Taylor and Francis Ltd., 2009) Ceylan, Çağatay; Severcan, Mete; Bozoğlu, Faruk; Severcan, FerideThe objective of this study was to investigate the effects of high hydrostatic pressure (HHP) on the stability of red blood cells (RBCs) and platelets. Bovine blood cells (n=5) were treated with the pressure of 55, 110, 154 and 220MPa at 25°C for 5min. Light microscopy, atomic force microscopy and flow cytometry studies revealed that RBCs were morphologically stable up until the 220MPa pressure treatments, at which surface modifications were observed. The platelets were found to be less stable than RBCs. HHP application did not cause any significant change in the signal intensity, band area and frequency values of the infrared bands with the exception that a significant variation was observed in the area of the cholesterol band. No statistically significant variations were observed in the secondary structure elements due to HHP treatment according to the artificial neural network study based on the FTIR data.