Publications by authors named "Tulin Ozkan"

19 Publications

  • Page 1 of 1

Assessment of azithromycin as an anticancer agent for treatment of imatinib sensitive and resistant CML cells.

Leuk Res 2021 03 6;102:106523. Epub 2021 Feb 6.

Department of Medical Biology, School of Medicine, Ankara University, Ankara, Turkey.

Introduction: Chronic Myeloid Leukemia (CML) is a hematological disease which is characterized by the presence of BCR-ABL fusion protein. Imatinib (IMA), a tyrosine kinase inhibitor of BCR-ABL, is used as a frontline treatment.Although IMA aids in killing a majority of leukemia cells, it may not kill CML stem cells which are the primary roots of disease and therapy resistance. Recently, antimicrobial drugs have been gaining attention because of their selective targeting of cancer cells. Therefore, we now ask if combinational therapy of IMA with a targeted antimicrobial drug Azithromycin (AZT) can enhance the treatment efficiency in IMA resistant CML.

Methods: K562S (IMA sensitive) and K562R (IMA resistant) cells were treated with increasing concentrations of AZT to determine its effects on cell proliferation and apoptosis. Cell viability, apoptosis, caspase3/7 activity and P-glycoprotein (Pgp) function were investigated with spectrophotometric MTT assay and flow cytometric Annexin V staining, caspase 3/7 activity, and Rhodamine123 staining assays respectively. The expression levels of pro-apoptotic (BAX, BAD and BIM), anti- apoptotic (BCL-XL and BCL-2) and drug transporter (MDR-1 and MRP-1) genes were assessed with qRT-PCR.

Results: AZT treatment alone inhibited cell viability, induced apoptosis and enhanced caspase 3/7 activity in both K562S and high MDR-1 (Pgp) expressing K562R cells. Moreover, combination of AZT/IMA suppressed cell viability, induced apoptosis and caspase3/7 activity more effectively and significantly compared to K562R cells treated with only IMA or AZT. Furthermore, AZT and AZT/IMA combination decreased Pgp function in K562R cells in comparison with their controls. Based on qRT-PCR data, single AZT and combined AZT/IMA treatment also induced BAX/BCL-2 ratio significantly in both K562S and K562R cells.

Conclusion: Single AZT and AZT/IMA combinational treatment can be proposed as a promising and effective treatment strategy for CML. One of the mechanisms underlying the potent anticancer effect of combined AZT/IMA could be its ability to inhibit Pgp function and increase intracellular accumulation of IMA which leads to the induction of apoptosis in K562R cells.
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http://dx.doi.org/10.1016/j.leukres.2021.106523DOI Listing
March 2021

Cytotoxic effect of 6-Shogaol in Imatinib sensitive and resistant K562 cells.

Mol Biol Rep 2021 Feb 30;48(2):1625-1631. Epub 2021 Jan 30.

Department of Medical Biology, School of Medicine, Ankara University, Ankara, Turkey.

Chronic Myeloid Leukemia (CML) is a clonal hematopoietic malignancy characterized by the formation of BCR-ABL fusion protein. Imatinib (IMA) is a BCR-ABL tyrosine kinase inhibitor (TKI), which exhibited a high rate of response for newly diagnosed CML patients. Emergence of IMA resistance considered as a major challenge in CML therapy. Recent studies reported the anti-cancer effect of natural extracts such as 6-Shogaol (6-SG) which is extracted from ginger and the mechanisms involved in targeting of cancer cells. In the present study, we aimed to explore the potential anticancer effect of 6-SG on K562S (Imatinib sensitive) and K562R (Imatinib resistant) cells. K562S and K562R cells were incubated with increasing concentrations of 6-SG (5 μM- 50 μM) to determine its cytotoxic and apoptotic effects. Cell viability and apoptosis were investigated with spectrophotometric MTT assay and flow cytometric Annexin V staining, respectively. The mRNA expression levels of apoptotic related genes (BAX and BCL-2) and drug transporter (MDR-1 and MRP-1) genes were evaluated with qRT-PCR. According to our results, 6-SG treatment inhibited cell viability, induced apoptosis in both K562S and K562R cells. Based on our RT-PCR results, 6-SG enhanced pro-apoptotic BAX gene and decreased anti-apoptotic BCL-2 gene expression levels significantly in both treated K562S and K562R cells. Furthermore, 6-SG increased MDR-1 mRNA expression level in K562S and K562R cells in comparison with their control counterparts. Whereas, 6-SG decrease MRP-1 mRNA expression level in K562S cells significantly. It is the first study that reveals the apoptotic effect of 6-SG in CML cell line and IMA resistance. Therefore, 6-SG treatment can be suggested as a promising strategy for CML therapy.
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http://dx.doi.org/10.1007/s11033-021-06141-2DOI Listing
February 2021

Methods for simultaneous and quantitative isolation of mitochondrial DNA, nuclear DNA and RNA from mammalian cells.

Biotechniques 2020 12 26;69(6):436-442. Epub 2020 Oct 26.

Institute for Regenerative Medicine & Biotherapy (IRMB), INSERM, Univ Montpellier, F-34090 Montpellier, France.

The aim of this study was to assess two protocols for their capacities to simultaneously isolate RNA, mtDNA and ncDNA from mammalian cells. We compared the Invitrogen TRIzol-based method and Qiagen DNeasy columns, using the HepG2 cell line and human primary glioblastoma stem cells. Both methods allowed the isolation of all three types of nucleic acids and provided similar yields in mtDNA. However, the yield in ncDNA was more than tenfold higher on columns, as observed for both cell types. Conversely, the TRIzol method proved more reproducible and was the method of choice for isolating RNA from glioblastoma cells, as demonstrated for the housekeeping genes and .
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http://dx.doi.org/10.2144/btn-2020-0114DOI Listing
December 2020

The impact of tumor and gut microbiotas on cancer therapy: Beneficial or detrimental?

Life Sci 2019 Sep 22;233:116680. Epub 2019 Jul 22.

Kidney Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. Electronic address:

Cancer is a globally challenging health problem threatening mankind. Despite therapeutic advances in dealing with this malignancy, heterogeneous response and resistance to chemotherapeutic agents remain the hallmarks of cancer therapy. On the other hand, the involvement of the microbiota in affecting human health is well defined. An ever-growing body of evidence implicates the potential link between the microbiome and the efficacy of cancer therapies. Gut microbiota can modulate the metabolism of drugs in a number of ways. The presence of bacteria within the tumor environment can also impact the responses to cancer therapies; changing the chemical structure of chemotherapeutic drugs, affecting their activity, and local concentration. However, the underlying mechanisms by which gut and tumor microbial communities affect the response to cancer therapy are poorly understood and deciphering these mechanisms is of paramount importance. This review provides an overview of how gut and tumor microbiota might affect the efficacy of chemotherapy, radiotherapy, and immunotherapy and alleviate the adverse side effects of these therapies for the development of personalized and effective anticancer therapy.
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http://dx.doi.org/10.1016/j.lfs.2019.116680DOI Listing
September 2019

Expressions of homeobox, collagen and estrogen genes in women with uterine prolapse.

Eur J Obstet Gynecol Reprod Biol 2019 Feb 29;233:26-29. Epub 2018 Nov 29.

Ankara University, School of Medicine, Department of Biostatistics, Ankara, Turkey.

Objective: Genetic contribution is thought to be involved in the pathophysiology of pelvic organ prolapse (POP). We aimed to study the gene expression profiles of the genes HomeoboxA11 (HOXA11), HomeoboxA13 (HOXA13), Collagen Type I (COL1A), Collagen Type III (COL3A), estrogen receptor genes (ESR1 and ESR2) of round (RL) and uterosacral ligaments (USL) in postmenopausal women with uterine prolapse.

Study Design: Gene expressions of 32 postmenopausal women with prolapse were analysed according to gene expressions of 8 postmenopausal women without prolapse. Quantitative real-time PCR (qRT-PCR) method was used for the detection of expression levels of the genes. Student's t-Test and Mann-Whitney U test were used for statistical analysis.

Results: In the USL specimens of all women with uterine prolapse HOXA13 and ESR1 gene expressions were decreased compared to controls (0.5 fold, p = 0.04 and 0.82 fold, p = 0.04, respectively). In the RL specimens, ESR2 gene expression was decreased 0.7 fold in women with prolapse when compared to controls (p = 0.04). In the USL specimens of women with advanced stages of prolapse (stage ≥3), HOXA13 and COL3A gene expressions were decreased compared to controls (0.44 fold, p = 0.043 and 0.39 fold, p = 0.045, respectively). In the RL specimens, ESR2 gene expression was decreased 0.65 fold in women with prolapse when compared to controls (p = 0.052).

Conclusion: The significant decrease in the expression of the genes HOXA13, COL3A in the USL and ESR2 in the RL especially in advanced stages of prolapse, implicate that these gene expressions may play a role in the development of uterine prolapse.
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http://dx.doi.org/10.1016/j.ejogrb.2018.11.019DOI Listing
February 2019

Expression analysis of Akirin-2, NFκB-p65 and β-catenin proteins in imatinib resistance of chronic myeloid leukemia.

Hematology 2018 Dec 26;23(10):765-770. Epub 2018 Jun 26.

a Faculty of Pharmacy, Department of Biochemistry , Ankara University , Ankara , Turkey.

Objective: Chronic myleoid leukemia (CML) is a myeloproliferative disorder characterized with the constitutive activation of Bcr-Abl tyrosine kinase which is a target for imatinib, the first line treatment option for CML. Constitutive activation of NFκB and β-catenin signaling promotes cellular proliferation and survival and resistance to Imatinib therapy in CML. Akirin-2 is a nuclear protein which is required for NFκB dependent gene expression as a cofactor and has been linked to Wnt/beta-catenin pathway. The purpose of this study is to examine Akirin-2, NFκB and β-catenin in imatinib resistance of CML and to test if any direct physical protein-protein interaction exists between NFkB and both β-catenin and Akirin-2.

Methods: RT-PCR and western blot were performed to determine Akirin-2, NFκB-p65 and β-catenin gene and protein expressions, Co-immunoprecipitation and chromatin immunoprecipitation analysis were carried out to detect the direct physical interactions and binding of NFκB-p65 and β-catenin proteins to MDR1 promoter region, respectively.

Results: β-catenin and NFκB-p65 proteins bound to DNA promoter regions of MDR1 in imatinib-sensitive and resistant CML cells, whereas any direct protein-protein interaction could not be found between NFκB-p65 and Akirin-2 or β-catenin proteins. Nuclear β-catenin and NFκB-p65 levels increased in imatinib resistance. Moreover, increased Akirin-2 protein accumulation in the nucleus was shown for the first time in imatinib resistant CML cells.

Discussion: We show for the first time that Akirin-2 can be a novel biomarker in imatinib resistance. Targeting Akirin-2, NFκB and β-catenin genes may provide an opportunity to overcome imatinib resistance in CML.
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http://dx.doi.org/10.1080/10245332.2018.1488795DOI Listing
December 2018

Characterization of imatinib-resistant K562 cell line displaying resistance mechanisms.

Cell Mol Biol (Noisy-le-grand) 2018 May 15;64(6):23-30. Epub 2018 May 15.

Department of Medical Biology, School of Medicine, Ankara University, Ankara, Turkey.

Chronic myeloid leukemia (CML) is a hematopoietic malignancy characterized by the t(9; 22) and the related oncogene, BCR-ABL. Tyrosine kinase activity of fusion protein BCR-ABL is the main cause of CML. Even if imatinib is used as a tyrosine kinase inhibitor (TKI) for CML therapy, drug resistance may occur in patients and the clinical failure of imatinib treatment in resistant patients had resulted with the use of another alternative TKIs. BCR-ABL dependent and independent molecular mechanisms have crucial roles in drug resistance. To reveal the underlying molecular mechanisms which play significant roles in imatinib resistance in CML, we established K562 imatinib-resistant cell line (K562r5) which was continuously exposed to (5µM) imatinib to investigate molecular mechanisms which play significant roles in drug resistance. First of all, we analyzed T315I, M351T, F315L and F359C/L/V mutations with DNA sequencing as a BCR-ABL dependent mechanism in our cell lines. Moreover, we investigated BCR-ABL independent mechanisms such as apoptosis, autophagy, drug transport and DNA repair which affect drug resistance in these cell lines. In vitro cell viability was determined by MTT assay. DNA sequencing analysis was performed to detect BCR-ABL mutations. The apoptotic effect of imatinib on CML cell lines was tested by flow cytometric Annexin V-PE staining and caspase activation assays. Apoptotic, autophagic, drug transporter and DNA repair genes expression levels were determined by RT-PCR. The conventional cytogenetic analysis was performed on K562s and K562r cells. Our results indicate that inhibition of apoptosis, induction of autophagy, overexpression of efflux gene MDR1 and down-regulation of influx gene OCT1 play crucial roles in the progression of imatinib resistance.
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May 2018

Determination of the Apoptotic Effect and Molecular Docking of Benzamide Derivative XT5 in K562 Cells.

Anticancer Agents Med Chem 2018 ;18(11):1521-1530

Department of Medical Biology, School of Medicine, Ankara University, Ankara, Turkey.

Background: The tyrosine kinase inhibitor, imatinib, used as a first line treatment in Chronic Myeloid Leukemia (CML) patients, may lead to resistance and failure to therapy. Novel combinations of imatinib with other drugs is a strategy to improve treatment efficiency.

Objective: In this study, the antileukemic and apoptotic effects of a benzamide derivative XT5 and benzoxazole derivative XT2B and their combination with imatinib were investigated in imatinib-sensitive (K562S) and imatinib-resistant (K562R) CML cells.

Methods: In vitro cytotoxicity was determined by MTT assay. Then, apoptotic effect of XT5 on CML cell lines was tested by Annexin V flow cytometry, caspase activation and RT-PCR. Docking calculation was performed using AutoDock Vina in PyMOL environment using AutoDock/Vina plugin for PyMOL.

Results: According to our MTT assay data, XT5 indicated significant antiproliferative effect on cell lines, therefore we investigated apoptotic effects of XT5. Treatment of K562 cell lines with a combination of XT5 and imatinib-XT5 increased cytotoxicity, the Annexin V binding and caspase 3/7 activation. In addition to apoptosis assays, we observed an increase in the expression levels of the pro-apoptotic (BAX, BAD and BIM) genes in XT5 treated K562R and K562S cells. Molecular modelling experiments showed that XT5 showed hydrogenbonding interactions with important amino acids of BCR-ABL kinase receptor; however XT2B did not show any hydrogen bond interaction.

Conclusion: Our results indicate that XT5 could be a potential candidate to be used as a new anticancer drug and XT5 combination with imatinib as an alternate treatment strategy for overcoming imatinib resistance.
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http://dx.doi.org/10.2174/1871520618666171229222534DOI Listing
July 2019

Genetic Polymorphisms in PRM1, PRM2, and YBX2 Genes are Associated with Male Factor Infertility.

Genet Test Mol Biomarkers 2018 Jan 11;22(1):55-61. Epub 2017 Dec 11.

7 Reproductive Health Research Center, School of Medicine, Ankara University , Ankara, Turkey .

Aims: The etiology of infertility is still unknown in almost half of all male infertility patients. In sperm, DNA condensation differs from somatic and female gamete cells, with the protamine (PRM) gene and its transcription factor, Y-box binding protein 2 (YBX2), playing key roles in making the structure more compact. Protamine polymorphisms have been studied in different populations, but various results have been acquired.

Materials And Methods: In our study, we examined, for the first time in a Turkish population, the association between protamine gene alleles (PRM1 c.-190C>A, PRM1 c.197G>T, and PRM2 c.248C>T), and YBX2 (c.187T>C and c.1095 + 16A>G) and male infertility. This was accomplished using polymerase chain reaction-restriction fragment length polymorphism analyses of 100 infertile and 100 fertile Turkish men. Sperm DNA fragmentation analysis was performed using the Comet technique.

Results: We found that the AA and CA genotypes of the PRM1 c.-190C>A polymorphism had a significant association with infertility (p < 0.001) and the AA genotype was also highly significantly associated with high sperm DNA damage (p < 0.001).

Conclusion: This study demonstrates that the PRM1 c.-190C>A polymorphism is associated with sperm DNA fragmentation, which may impact male infertility in the Turkish population. Further research with larger groups and in various other study populations will be required to clarify the impact of protamine and YBX2 gene polymorphisms on male infertility.
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http://dx.doi.org/10.1089/gtmb.2017.0040DOI Listing
January 2018

Incomplete Antibodies May Reduce ABO Cross-Match Incompatibility: A Pilot Study.

Turk J Haematol 2018 Mar 23;35(1):54-60. Epub 2017 May 23.

Ankara University Faculty of Medicine, Department of Hematology, Ankara, Turkey.

Objective: Any erythrocyte transfusion among humans having type A or B blood groups is impossible due to antibodies causing fatal transfusion complications. A cross-match test is performed to prevent immune transfusion complications before transfusion. Our hypothesis is that the fragment antibody (Fab) part of the antibody (incomplete antibody) may be used to prevent an immune stimulus related to the complete antibody. Therefore, we designed a pilot study to evaluate the effectiveness of these incomplete antibodies using cross-match tests.

Materials And Methods: Pepsin enzyme and staphylococcal protein A columns were used to cut anti-A and anti-B monoclonal antibodies and purify their Fab (2) fragments, respectively. An Rh-positive erythrocyte suspension with purified anti-A Fab (2) solution and B Rh-positive erythrocyte suspension with purified anti-B Fab (2) solution were combined correspondingly. Cross-match tests were performed by tube and gel centrifugation methods. The agglutination levels due to the anti-A and anti-B Fab (2) antibodies and their effects on the agglutination normally observed with complete antibodies were then measured.

Results: No agglutination for the purified incomplete anti-A Fab (2) with A Rh+ erythrocyte and anti-B Fab (2) with B Rh+ erythrocyte combinations was observed in the tube cross-match tests. These agglutination levels were 1+ in two wells in the gel centrifugation cross-match tests. Fab (2)-treated erythrocytes were also resistant to the agglutination that normally occurs with complete antibodies.

Conclusion: We determined that the Fab (2) fragments of antibodies may not only be used to obtain a mild or negative reaction when compared to complete antibodies, but they might also be used for decreasing ABO incompatibility. Incomplete antibodies might be a therapeutic option in autoimmune hemolytic anemia and they may also be used in solid organ or hematopoietic stem cell transplantation. Therefore, we have planned an in vivo study to prove these in vitro findings.
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http://dx.doi.org/10.4274/tjh.2016.0504DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5843775PMC
March 2018

Apoptotic Effects of Some Tetrahydronaphthalene Derivatives on K562 Human Chronic Myelogenous Leukemia Cell Line.

Anticancer Agents Med Chem 2018 02;17(14):1924-1930

Department of Biochemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey.

Background: Retinoids which are vitamin A (Retinol) derivatives have been suggested to mediate the inhibition of cancer cell growth and apoptosis. It has been reported that all trans retinoic acid (ATRA) exhibited suppressive effects on different types of leukemia including chronic myelogenous leukemia.

Objective: In the present study, we aim to find out the effects of 6 synthetic N-(3,5,5,8,8-pentamethyl-5,6,7,8- tetrahydronaphthalene-2-yl)-carboxamide derivatives (compound 6-12) on cell viability and apoptotic pathways in K562 human chronic myelogenous leukemia cell line.

Methods: Cell viability and apoptosis were examined by spectrophotometric thiazolyl blue tetrazolium bromide (MTT) and caspase-3 assay, western blot, RT-PCR and flow cytometry.

Results: Our results indicated that compound 6 (5-(1,2-Dithiolan-3-yl)-N-(3,5,5,8,8-pentamethyl-5,6,7,8- tetrahydronaphthalen-2-yl)pentanamide), 8 (4-(3,4-Dimethoxyphenyl)-N-(3,5,5,8,8-pentamethyl-5,6,7,8- tetrahydronaphthalen-2-yl)butanamide) and 11 (E-3-(4-Hydroxy-3-methoxyphenyl)-N-(3,5,5,8,8-pentamethyl- 5,6,7,8-tetrahydronaphthalen-2-yl)acrylamide) exhibited apoptotic effects in K562 human chronic myelogenous leukemia cell line and induced caspase 3, PARP cleavage, Bax/Bcl-2 ratio, Bad and Bim gene expressions.

Conclusion: Some retinoid derivatives tested in this study induced apoptosis of K562 cells which suggest that these compounds may serve as potential agents in the treatment of chronic myelogenous leukemia.
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http://dx.doi.org/10.2174/1871521409666170412122811DOI Listing
February 2018

Methylsulfonylmethane Induces p53 Independent Apoptosis in HCT-116 Colon Cancer Cells.

Int J Mol Sci 2016 Jul 15;17(7). Epub 2016 Jul 15.

Faculty of Pharmacy, Department of Biochemistry, Ankara University, 06100 Ankara, Turkey.

Methylsulfonylmethane (MSM) is an organic sulfur-containing compound which has been used as a dietary supplement for osteoarthritis. MSM has been shown to reduce oxidative stress and inflammation, as well as exhibit apoptotic or anti-apoptotic effects depending on the cell type or activating stimuli. However, there are still a lot of unknowns about the mechanisms of actions of MSM. In this study, MSM was tested on colon cancer cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay and flow cytometric analysis revealed that MSM inhibited cell viability and increased apoptotic markers in both HCT-116 p53 +/+ and HCT-116 p53 -/- colon cancer cells. Increased poly (ADP-ribose) polymerase (PARP) fragmentation and caspase-3 activity by MSM also supported these findings. MSM also modulated the expression of various apoptosis-related genes and proteins. Moreover, MSM was found to increase c-Jun N-terminal kinases (JNK) phosphorylation in both cell lines, dose-dependently. In conclusion, our results show for the first time that MSM induces apoptosis in HCT-116 colon cancer cells regardless of their p53 status. Since p53 is defective in >50% of tumors, the ability of MSM to induce apoptosis independently of p53 may offer an advantage in anti-tumor therapy. Moreover, the remarkable effect of MSM on Bim, an apoptotic protein, also suggests its potential use as a novel chemotherapeutic agent for Bim-targeted anti-cancer therapies.
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http://dx.doi.org/10.3390/ijms17071123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4964498PMC
July 2016

Synthesis and antiproliferative evaluation of novel 5-(4-methylpiperazin-1-yl)-2-phenyl- 1H-benzimidazole derivatives.

Z Naturforsch C J Biosci 2015 ;70(3-4):79-85

A series of novel 5-(4-methylpiperazin-1-yl)-2-phenyl-1H-benzimidazoles (5-14) were synthesized and evaluated for their in vitro antiproliferative activities against the human leukemia cell line HL-60. Compounds 5-7 and 10-12 exhibited potent antiproliferative activities against this cell line. The quantitative analysis of apoptosis by flow cytometry demonstrated that the percentages of apoptotic HL-60 cells treated with compounds 5 and 10-12 were significantly higher than in the control.
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http://dx.doi.org/10.1515/znc-2014-4189DOI Listing
October 2015

Methylation analysis of the DAPK1 gene in imatinib-resistant chronic myeloid leukemia patients.

Oncol Lett 2015 Jan 6;9(1):399-404. Epub 2014 Nov 6.

Department of Medical Biology, Faculty of Medicine, Ankara University, Sihhiye, Ankara 06100, Turkey.

Death-associated protein kinase-1 () is a pro-apoptotic gene that induces cellular apoptosis in response to internal and external apoptotic stimulants. The silencing of can result in uncontrolled cell proliferation, indicating that it may have a role in tumor suppression. activity can be inhibited by the cytosine methylation that occurs in its promoter region. These methylation changes in the promoter region of have been reported in a range of solid and hematological malignancies. In the present study, methylation was investigated in chronic myeloid leukemia patients (n=43) using bisulfite conversion followed by methylation-specific polymerase chain reaction. The present study included a number of patients who were identified to be resistant to the common chemotherapeutic agent imatinib (STI571, Gleevec, Glivec), exhibiting at least one mutation in the breakpoint cluster region-Abelson murine leukemia () gene. Thus, the patients in the present study were divided into two groups according to their response to imatinib therapy: Non-resistant (n=26) and resistant (n=17) to imatinib. Resistant patients were characterized by the presence of single or multiple mutations of the gene: i) T315I, ii) M351T, iii) E255K, iv) T315I and M351T or v) T315I, M351T and E255K. The present study identified that: i) The incidence of methylation was significantly higher in the resistant patients compared with the non-resistant patients; ii) the extent of resistance varied between mutation types; and iii) there was no methylation in any of the healthy controls. These findings indicate that methylation may be associated with a signaling pathway for imatinib resistance in chronic myeloid leukemia.
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http://dx.doi.org/10.3892/ol.2014.2677DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4246661PMC
January 2015

Synthesis and anticancer effects of some novel 2-(4-phenoxyphenyl)-1H-benzimidazole derivatives on K562 cell line.

Arch Pharm Res 2015 18;38(5):650-8. Epub 2014 Jul 18.

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, Tandogan, 06100, Ankara, Turkey,

A series of novel 2-(4-phenoxyphenyl)-1H-benzimidazole derivatives was synthesized and tested in vitro on human chronic myelogenous leukemia (CML) cell line K562. Benzimidazoles containing 5-amidino (10), 5-N-isopropylamidino (11), 5-bromo (13), and 5,6-dimethyl (14) derivatives exhibited remarkable cytotoxic activity. The quantitative analysis of apoptosis by flow-cytometry demonstrated that the percentages of early and late apoptotic K562 cells treated with these compounds were significantly higher than cells without treatment. We also investigated the effects of these compounds on the expression of apoptosis-related genes BAX, BCL-2, BAD and BIM. Treatment of K562 cells wih compounds 10-14 significantly increased the expression levels of the proapoptotic genes BAX, BAD and BIM, whereas compound 20 increased BAX and BAD.
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http://dx.doi.org/10.1007/s12272-014-0438-xDOI Listing
February 2016

Peripheral blood mononuclear cell microchimerism in Turkish female patients with systemic sclerosis.

Mod Rheumatol 2014 Jan;24(1):97-105

Division of Rheumatology, Sanliurfa Education and Research Hospital , 63100 Sanliurfa , Turkey.

Objectives: To investigate microchimerism (Mc) in peripheral blood mononuclear cells (PBMC) taken from female patients with systemic sclerosis (SSc) and healthy females. We also intended to research the association between Mc and the clinical subsets.

Methods: This study included 50 females with lcSSc, 30 females with dcSSc and 40 healthy females. The Y-chromosome sequences were studied by RT-PCR in DNA obtained from PBMC.

Results: Mc was found in 28 (35 %) patients and 8 (20 %) healthy controls as well as in 6 dcSSc patients with son(s) (27.3 %), 10 lcSSc patients with son(s) (32.3 %) and 7 control females with son(s) (18.9 %) (p > 0.05). Mc was detected in 6 nulliparous lcSSc patients (31.6 %) and in 1 nulliparous dcSSc patient (11.1 %) (p > 0.05). The mean time elapsed between the first pregnancy and the diagnosis of SSc was 3.5 (0-49) years in the Mc-positive patients and 14 (0-55) years in the negative patients (p = 0.020). The mean modified Rodnan skin scores (ModRSS) of the patients with and without Mc was 10 (4-24) and 13 (4-26), respectively (p = 0.038). The relationship between Mc and the system involvement, disease severity, autoantibody profile, number of children and age of children was not found.

Conclusions: Various etiological factors rather than just one play a role in the development of scleroderma. Mc is thought to be one factor that shortens the elapsed time of disease development in SSc. Mc is inversely related to the ModRSS, and no association was detected between Mc and autoantibodies or the clinical subsets.
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http://dx.doi.org/10.3109/14397595.2013.854052DOI Listing
January 2014

Synthesis and cytotoxic evaluation of novel N-substituted amidino-1-hydroxybenzimidazole derivatives.

Arch Pharm Res 2014 May 9;37(5):580-7. Epub 2013 Jul 9.

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, 06100, Tandogan, Ankara, Turkey,

A new class of N-substituted amidino-1-hydroxybenzimidazole derivatives (15-24) were synthesized and evaluated for their in vitro cytotoxic activities against human leukemia cell lines, HL-60 and K562. The preliminary results showed that compounds 16, 20, 21 and 23 had moderate antitumor activity against HL-60 cell line. Further investigation on the mechanism of the observed cytotoxic effects demonstrated that compound 21 increased the expression of autophagic and apoptotic genes and induced apoptosis of HL-60 cells.
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http://dx.doi.org/10.1007/s12272-013-0197-0DOI Listing
May 2014

Effect of lomeguatrib-temozolomide combination on MGMT promoter methylation and expression in primary glioblastoma tumor cells.

Tumour Biol 2013 Jun 22;34(3):1935-47. Epub 2013 Mar 22.

Department of Medical Biology, Ankara University School of Medicine, Ankara, Turkey.

Temozolomide (TMZ) is commonly used in the treatment of glioblastoma (GBM). The MGMT repair enzyme (O (6)-methylguanine-DNA methyltransferase) is an important factor causing chemotherapeutic resistance. MGMT prevents the formation of toxic effects of alkyl adducts by removing them from the DNA. Therefore, MGMT inhibition is an interesting therapeutic approach to circumvent TMZ resistance. The aim of the study was to investigate the effect of the combination of lomeguatrib (an MGMT inactivator) with TMZ, on MGMT expression and methylation. Primary cell cultures were obtained from GBM tumor tissues. The sensitivity of primary GBM cell cultures and GBM cell lines to TMZ, and to the combination of TMZ and lomeguatrib, was determined by a cytotoxicity assay (MTT). MGMT and p53 expression, and MGMT methylation were investigated after drug application. In addition, the proportion of apoptotic cells and DNA fragmentation was analyzed. The combination of TMZ and lomeguatrib in primary GBM cell cultures and glioma cell lines decreased MGMT expression, increased p53 expression, and did not change MGMT methylation. Moreover, apoptosis was induced and DNA fragmentation was increased in cells. In addition, we also showed that lomeguatrib-TMZ combination did not have any effect on the cell cycle. Finally, we determined that the sensitivity of each primary GBM cells and glioma cell lines to the lomeguatrib-TMZ combination was different and significantly associated with the structure of MGMT methylation. Our study suggests that lomeguatrib can be used with TMZ for GBM treatment, although further clinical studies will be needed so as to determine the feasibility of this therapeutic approach.
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http://dx.doi.org/10.1007/s13277-013-0738-7DOI Listing
June 2013

The roles of epigenetic modifications of proapoptotic BID and BIM genes in imatinib-resistant chronic myeloid leukemia cells.

Hematology 2013 Jul 25;18(4):217-23. Epub 2013 Jan 25.

Department of Basic Oncology, Insitute of Oncology, Hacettepe University, Ankara, Turkey.

In chronic myeloid leukemia (CML), epigenetic modifications such as promoter hypermethylation and inactive histone modification are known mechanisms of drug resistance. In our study, we investigated the roles of promoter hypermethylation of BIM and BID genes and H3K27me3 histone modification on imatinib resistance. We detected higher expression levels of BIM and BID genes and lower expression levels of EZH2, EED2, SIRT1, and SUZ12 genes in imatinib-resistant K562/IMA-3 cells compared to imatinib-non-resistant K562 cells. While we determined the EZH2 and DNMT enzymes as bounded to the promoter of the BIM gene, we did not detect hypermethylation of this promoter. We also found the H3K27me3 histone modification promoter of BIM and BID genes in both cell lines. In conclusion, our results support the notion that DNA promoter methylation may be formed independently from EZH2-H3K27me3 and pro-apoptotic BIM and BID genes are not methyllated in the imatinib resistance of CML cells.
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http://dx.doi.org/10.1179/1607845412Y.0000000056DOI Listing
July 2013
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