Molecular Biology and Genetics / Moleküler Biyoloji ve Genetik
Permanent URI for this collectionhttps://hdl.handle.net/11147/9
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Article Citation - WoS: 6Citation - Scopus: 7Nilotinib Does Not Alter the Secretory Functions of Carotid Artery Endothelial Cells in a Prothrombotic or Antithrombotic Fashion(SAGE Publications Inc., 2015) Katgı, Abdullah; Sevindik, Ömer Gökmen; Adan Gökbulut, Aysun; Özsan, Güner Hayri; Yüksel, Faize; Solmaz, Şerife Medeni; Alacacıoğlu, İnci; Özcan, Mehmet Ali; Demirkan, Fatih; Baran, Yusuf; Pişkin, ÖzdenBackground: There have been concerns about the possible prothrombotic effects of nilotinib, especially in patients having cardiovascular risk factors. The potential mechanism behind the increased risk of thromboembolic events is still not clear. Objectives: In this study, we aimed to evaluate possible harmful effects of nilotinib on endothelial cells. To this aim, we examined proliferative capacity and secretory functions of healthy human carotid artery endothelial cells (HCtAECs) in response to nilotinib. Methods: 3-(4,5-Dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) cell proliferation method was used to determine antiproliferative effects of nilotinib on HCtAECs. The HCtAECs were incubated with 5, 10, and 100 nmol/L doses of nilotinib for 72 hours. Then, in order to assess the endothelial function, levels of nitric oxide (NO), von Willebrand factor (vWF), tissue plasminogen activator, plasminogen activator inhibitor 1 (PAI-1), and endothelin 1 (ET-1) were evaluated using enzyme-linked immunosorbent assay from tissue culture supernatants. Results: There were slight but statistically significant decreases in cell proliferation in response to nilotinib. Nilotinib increased the secretion of t-PA, PAI-1, and vWF in a dose-dependent manner when compared with the untreated control group. The ET-1 secretion was lower in 5 nmol/L and higher in 10 and 100 nmol/L nilotinib-treated cells as compared to untreated cells. Regarding NO secretion, lower levels were observed in 5 and 10 nmol/L, and higher levels were detected in 100 nmol/L nilotinib-treated cells as compared to untreated control group cells. Conclusion: Considering the results obtained in our study, nilotinib does not affect the functions of endothelial cells either in a prothrombotic or an antithrombotic fashion, despite a dose-dependent decline in cell viability.Article Citation - WoS: 13Citation - Scopus: 13Macromolecular Changes in Nilotinib Resistant K562 Cells; an in Vitro Study by Fourier Transform Infrared Spectroscopy(SAGE Publications Inc., 2012) Ceylan, Çağatay; Camgöz, Aylin; Baran, YusufNilotinib is a second generation tyrosine kinase inhibitor which is used in both first and second line treatment of chronic myeloid leukemia (CML). In the present work, the effects of nilotinib resistance on K562 cells were investigated at the molecular level using Fourier transform infrared (FT-IR) spectroscopy. Human K562 CML cells were exposed to step-wise increasing concentrations of nilotinib, and sub-clones of K562 cells resistant to 50 nM nilotinib were generated and referred to as K562/NIL-50 cells. Antiproliferative effects of nilotinib were determined by XTT cell proliferation assay. Changes in macromolecules in parental and resistant cells were studied by FT-IR spectroscopy. Nilotinib resistance caused significant changes which indicated increases in the level of glycogen and membrane/lipid order. The amount of unsaturated lipids increased in the nilotinib resistant cells indicating lipid peroxidation. The total amount of lipids did not change significantly but the relative proportion of cholesterol and triglycerides altered considerably. Moreover, the transcriptional status decreased but metabolic turn-over increased as revealed by the FT-IR spectra. In addition, changes in the proteome and structural changes in both proteins and the nucleus were observed in the K562/NIL-50 cells. Protein secondary structural analyses revealed that alpha helix structure and random coil structure decreased, however, anti-parallel beta sheet structure, beta sheet structure and turns structure increased. These results indicate that the FT-IR technique provides a method for analyzing drug resistance related structural changes in leukemia and other cancer types.Article Citation - WoS: 7Citation - Scopus: 8Mir-17 in Imatinib Resistance and Response To Tyrosine Kinase Inhibitors in Chronic Myeloid Leukemia Cells(Zerbinis Medical Publications, 2013) Fıratlıgil, Burcu; Biray Avcı, Çığır; Baran, YusufIn this study we examined the expression levels of miR-17 which possesses oncogenic activities through downregulation of CDKN1A, p21 and E2F1 tumor suppressor genes, in imatinib sensitive and resistant chronic myeloid leukemia (CML) cells. On the other hand, we also determined the expression levels of miR-17 in response to tyrosine kinase inhibitors imatinib, nilotinib and dasatinib used for the treatment of CML. Methods: The expression profiles of miR-17 were analysed by Stem-Loop reverse transcription (RT) polymerase chain reaction (PCR). Results: The results revealed significant increase in the expression levels of miR-17 in imatinib sensitive and resistant cells compared to peripheral blood mononuclear cells (PBMCs). On the other hand, significant decrease was observed in miR-17 levels in response to imatinib, nilotinib and dasatinib. Conclusion: These results may imply that miR-17 can be used for diagnosis and treatment of CML.Article Citation - WoS: 24Citation - Scopus: 24Mechanisms Responsible for Nilotinib Resistance in Human Chronic Myeloid Leukemia Cells and Reversal of Resistance(Informa Healthcare, 2013) Camgöz, Aylin; Gençer, Emel Başak; Ural, Ali Uğur; Baran, YusufMultidrug resistance remains a significant obstacle to successful chemotherapy. The ability to determine the possible resistance mechanisms and surmount the resistance is likely to improve chemotherapy. Nilotinib is a very effective drug in the treatment of imatinib-sensitive or -resistant patients. Although very successful hematologic and cytogenetic responses have been obtained in nilotinib-treated patients, in recent years cases showing resistance to nilotinib have been observed. We aimed to examine the mechanisms underlying nilotinib resistance and to provide new targets for the treatment of chronic myeloid leukemia (CML). There was an up-regulation of antiapoptotic BCR/ABL, GCS and SK-1 genes and MRP1 transporter gene and down-regulation of apoptotic Bax and CerS1 genes in nilotinib-resistant cells. There was no mutation in the nilotinib-binding region of BCR/ABL in resistant cells. Inhibiton of GCS and SK-1 restored nilotinib sensitivity. Targeting the proteins that are involved in nilotinib resistance in addition to the inhibition of BCR/ABL could be a better method of treatment in CML.Article Citation - WoS: 16Citation - Scopus: 18Roles of Ceramide Synthase and Ceramide Clearence Genes in Nilotinib-Induced Cell Death in Chronic Myeloidleukemia Cells(Informa Healthcare, 2011) Camgöz, Aylin; Gençer, Emel Başak; Ural, Ali Uğur; Avcu, Ferit; Baran, YusufIn this study, we aimed to increase the sensitivity of human K562 and Meg-01 chronic myeloid leukemia (CML) cells to nilotinib by targeting bioactive sphingolipids, in addition to investigating the roles of ceramide metabolizing genes in nilotinib induced apoptosis. Cytotoxic effects of nilotinib, C8:ceramide, glucosyle ceramide synthase (GCS) and sphingosine kinase-1 (SK-1) inhibitors were determined by XTT cell proliferation assay and synergism between the agents was determined by isobologram analysis. Also, quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) results demonstrated that expression levels of longevity assurance (LASS) genes in response to nilotinib were correlated with sensitivity to nilotinib. For the first time, The results of this study showed for the first time that nilotinib induces apoptosis through upregulating ceramide synthase genes and downregulating SK-1 in CML cells in addition to inhibition of BCR/ABL. On the other hand, manipulating bioactive sphingolipids toward generation/accumulation of ceramides increased the apoptotic effects of nilotinib in CML cells.Article Citation - WoS: 7Citation - Scopus: 7Nilotinib Significantly Induces Apoptosis in Imatinib Resistant K562 Cells With Wild-Type Bcr-Abl, as Effectively as in Parental Sensitive Counterparts(Taylor and Francis Ltd., 2010) Ekiz, Hüseyin Atakan; Can, Geylani; Gündüz, Ufuk; Baran, YusufChronic myeloid leukemia (CML) is a hematological malignancy characterized by high levels of immature white blood cells. CML is caused by the translocation between chromosomes 9 and 22 (which results in the formation of the Philadelphia chromosome) creating BCR-ABL fusion protein. Imatinib and nilotinib are chemotherapeutic drugs which specifically bind to the BCR-ABL and inhibit cancer cells. Nilotinib is more effective in this respect than imatinib. We have shown that nilotinib induces apoptosis in imatinib-resistant K562 CML cells which have the wild-type BCR-ABL fusion gene almost to the same extent as it does in the parental sensitive cells by the increase in caspase-3 enzyme activity and the decrease in mitochondrial membrane potential. This effect of nilotinib, even in low concentrations, may indicate the efficacy of the usage of nilotinib in imatinib-resistant CML with less risk of undesired cytotoxic effects in the remaining cells of the body. © 2010 W. S. Maney & Son Ltd.