PubMed İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/397
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Article Citation - WoS: 33Citation - Scopus: 34Therapeutic Targeting of FLT3 in Acute Myeloid Leukemia: Current Status and Novel Approaches(Dove Medical Press Ltd, 2022-11) Tecik, Melisa; Adan, AysunFMS-like tyrosine kinase 3 (FLT3) is mutated in approximately 30% of acute myeloid leukemia (AML) patients. The presence of FLT3-ITD (internal tandem duplication, 20-25%) mutation and, to a lesser extent, FLT3-TKD (tyrosine kinase domain, 5- 10%) mutation is associated with poorer diagnosis and therapy response since the leukemic cells become hyperproliferative and resistant to apoptosis after continuous activation of FLT3 signaling. Targeting FLT3 has been the focus of many pre-clinical and clinical studies. Hence, many small-molecule FLT3 inhibitors (FLT3is) have been developed, some of which are approved such as midostaurin and gilteritinib to be used in different clinical settings, either in combination with chemotherapy or alone. However, many questions regarding the best treatment strategy remain to be answered. On the other hand, various FLT3-dependent and -independent resistance mechanisms could be evolved during FLT3i therapy which limit their clinical impact. Therefore, identifying molecular mechanisms of resistance and developing novel strategies to overcome this obstacle is a current interest in the field. In this review, recent studies of approved FLT3i and knowledge about major resistance mechanisms of clinically approved FLT3i's will be discussed together with novel treatment approaches such as designing novel FLT3i and dual FLT3i and combination strategies including approved FLT3i plus small-molecule agents targeting altered molecules in the resistant cells to abrogate resistance. Moreover, how to choose an appropriate FLT3i for the patients will be summarized based on what is currently known from available clinical data. In addition, strategies beyond FLT3i's including immunotherapeutics, small-molecule FLT3 degraders, and flavonoids will be summarized to highlight potential alternatives in FLT3-mutated AML therapy.Article Citation - WoS: 43Citation - Scopus: 49The Pleiotropic Effects of Fisetin and Hesperetin on Human Acute Promyelocytic Leukemia Cells Are Mediated Through Apoptosis, Cell Cycle Arrest, and Alterations in Signaling Networks(Sage Publications Ltd, 2015-06-17) Adan, Aysun; Baran, YusufFisetin and hesperetin, flavonoids from various plants, have several pharmaceutical activities including antioxidative, anti-inflammatory, and anticancer effects. However, studies elucidating the role and the mechanism(s) of action of fisetin and hesperetin in acute promyelocytic leukemia are absent. In this study, we investigated the mechanism of the antiproliferative and apoptotic actions exerted by fisetin and hesperetin on human HL60 acute promyelocytic leukemia cells. The viability of HL60 cells was evaluated using the MTT assay, apoptosis by annexin V/propidium iodide (PI) staining and cell cycle distribution using flow cytometry, and changes in caspase-3 enzyme activity and mitochondrial transmembrane potential. Moreover, we performed whole-genome microarray gene expression analysis to reveal genes affected by fisetin and hesperetin that can be important for developing of future targeted therapy. Based on data obtained from microarray analysis, we also described biological networks modulated after fisetin and hesperetin treatment by KEGG and IPA analysis. Fisetin and hesperetin treatment showed a concentration- and time-dependent inhibition of proliferation and induced G2/M arrest for both agents and G0/G1 arrest for hesperetin at only the highest concentrations. There was a disruption of mitochondrial membrane potential together with increased caspase-3 activity. Furthermore, fisetin- and hesperetin-triggered apoptosis was confirmed by annexin V/PI analysis. The microarray gene profiling analysis revealed some important biological pathways including mitogen-activated protein kinases (MAPK) and inhibitor of DNA binding (ID) signaling pathways altered by fisetin and hesperetin treatment as well as gave a list of genes modulated a parts per thousand yen2-fold involved in cell proliferation, cell division, and apoptosis. Altogether, data suggested that fisetin and hesperetin have anticancer properties and deserve further investigation.Article Citation - WoS: 18Citation - Scopus: 20Resveratrol Triggers Anti-Proliferative and Apoptotic Effects in FLT3-LTD Acute Myeloid Leukemia Cells via Inhibiting Ceramide Catabolism Enzymes(Humana Press inc, 2022-01-20) Ersoz, Nur Sebnem; Adan, AysunResveratrol possesses well-defined anti-carcinogenic activities. However, how resveratrol exerts its anti-leukemic actions by modulating anti-apoptotic ceramide catabolism enzymes, mainly sphingosine kinase (SK-1) and glucosylceramide synthase (GCS), in FLT3-ITD AML remains unclear. Resveratrol, SKI II (SK inhibitor) and PDMP (GCS inhibitor) were evaluated alone or in combinations for their effect on cell proliferation (MTT assay), apoptosis (annexin V-FITC/PI staining by flow cytometry) and cell cycle progression (PI staining by flow cytometry) in MOLM-13 and MV4-11 cells. The combination indexes (CIs) were calculated based on cell proliferation data using CompuSyn software. Caspase-3 and PARP activation, changes in SK-1 and GCS levels by resveratrol alone or PARP cleavage in co-treatments were determined by western blot. Resveratrol and inhibitors alone inhibited cell proliferation in a dose- and time-dependent manner. Resveratrol downregulated SK-1 and GCS expression in both cell lines. It induced apoptosis by phosphatidylserine (PS) exposure together with caspase-3 and PARP cleavage and arrested the cell cycle slightly at the S phase. Co-administrations intensified resveratrol's effect by inhibiting cell proliferation synergistically (A CI of < 1) or additively (A CI 1.0-1.1) and inducing apoptosis via PS relocalization and PARP cleavage. Resveratrol plus SKI II did not affect cell cycle progression significantly, however, resveratrol plus PDMP blocked cycle progression at G0/G1 and S phases for MOLM-13 cells and MV4-11 cells, respectively. Overall, resveratrol may inhibit FLT3-ITD AML cell proliferation by inhibiting ceramide catabolism and be evaluated as a chemopreventive after detailed analysis of the crosstalk between resveratrol and ceramide catabolism pathway.Article Citation - WoS: 496Citation - Scopus: 550Major Apoptotic Mechanisms and Genes Involved in Apoptosis(Sage Publications Ltd, 2016-04-09) Kiraz, Yagmur; Adan, Aysun; Yandim, Melis Kartal; Baran, Yusuf; Kartal Yandim, MelisAs much as the cellular viability is important for the living organisms, the elimination of unnecessary or damaged cells has the opposite necessity for the maintenance of homeostasis in tissues, organs and the whole organism. Apoptosis, a type of cell death mechanism, is controlled by the interactions between several molecules and responsible for the elimination of unwanted cells from the body. Apoptosis can be triggered by intrinsically or extrinsically through death signals from the outside of the cell. Any abnormality in apoptosis process can cause various types of diseases from cancer to auto-immune diseases. Different gene families such as caspases, inhibitor of apoptosis proteins, B cell lymphoma (Bcl)-2 family of genes, tumor necrosis factor (TNF) receptor gene superfamily, or p53 gene are involved and/or collaborate in the process of apoptosis. In this review, we discuss the basic features of apoptosis and have focused on the gene families playing critical roles, activation/inactivation mechanisms, upstream/downstream effectors, and signaling pathways in apoptosis on the basis of cancer studies. In addition, novel apoptotic players such as miRNAs and sphingolipid family members in various kind of cancer are discussed.Article Citation - WoS: 8Citation - Scopus: 8Involvement of Sphingolipid Metabolism Enzymes in Resveratrol-Mediated Cytotoxicity in Philadelphia-Positive Acute Lymphoblastic Leukemia(Routledge Journals, Taylor & Francis Ltd, 2021-11-22) Oguz, Osman; Adan, AysunTargeting the key enzymes of sphingolipid metabolism including serine palmitoyltransferase (SPT), sphingosine kinase (SK) and glucosylceramide synthase (GCS) has a therapeutic importance. However, sphingolipid metabolism-mediated anti-leukemic actions of resveratrol in Philadelphia-positive acute lymphoblastic leukemia (Ph + ALL) remain unknown. Therefore, we explored potential mechanisms behind resveratrol-mediated cytotoxicity in SD1 and SUP-B15 Ph + ALL cells in the context of sphingolipid metabolism and apoptosis induction. The anti-proliferative and apoptotic effects of resveratrol alone and in combination with SPT inhibitor (myriocin), SK inhibitor (SKI II), GCS inhibitor (PDMP) were determined by MTT cell proliferation assay and flow cytometry, respectively. The effects of resveratrol on PARP cleavage, SPT, SK and GCS protein levels were investigated by Western blot. Resveratrol inhibited proliferation and triggered apoptosis via PARP activation and externalization of phosphatidylserine (PS). Resveratrol increased the expression of SPT whereas it downregulated SK and GCS. Resveratrol's combinations with SKI II and PDMP intensified its anti-leukemic activity by increasing the relocalization of PS while its combination with myriocin suppressed apoptosis. Therefore, resveratrol inhibited cell proliferation and induced apoptosis through modulating SK, GCS and SPT expression, which may be considered as novel biomarkers of resveratrol-induced cytotoxicity in Ph + ALL.Article Functional Combination of Resveratrol and Midostaurin Induces Cytotoxicity to Overcome Acquired Midostaurin Resistance in FLT3-ITD Expressing Acute Myeloid Leukemia Cells(Springer, 2025-08-20) Tecik, Melisa; Adan, AysunThe most important challenge in treating FLT3-ITD AML is the development of resistance to FLT3 inhibitors, such as midostaurin, via both FLT3-dependent and FLT3-independent mechanisms. The study explored the potential cytotoxic effects of combining resveratrol and midostaurin on the sensitization of midostaurin-resistant cells. MTT assay revealed resveratrol's chemo-sensitizing influence on midostaurin-resistant cells, and combination indexes (CI) were calculated using Chou-Talalay's method. Apoptosis induction and cell cycle progression was analyzed by flow cytometry. The apoptotic molecular markers caspase 3, PARP, Bcl-2, and Bax were analyzed using a western blot. Sphingosine kinase-1 (SK-1) expression, total and phosphorylated FLT3, and STAT5A levels were measured using western blotting. Resveratrol enhanced the cytotoxic effects of midostaurin additively in resistant MV4-11MR and MOLM-13MR cells. It effectively reversed midostaurin resistance by inhibiting the activating phosphorylation of FLT3, STAT5A, and modulating the expression of SK-1 while concurrently increasing the levels of cleaved caspase-3 and PARP without noticeable alterations in Bax/Bcl-2 ratios except MV4-11MR cells. Additionally, there was an arrest at the S or G0/G1 phase of the cell cycle, depending on the resistant cells, compared to midostaurin alone, but not to the control group. In conclusion, the FLT3/STAT5A axis and SK-1 might play an important role in the reversal of midostaurin resistance by resveratrol. Therefore, the concurrent administration of resveratrol plus midostaurin could potentially serve as a therapeutic approach to address midostaurin resistance and enhance the overall therapy efficacy for FLT3-ITD AML patients after being validated with future in vivo and ex vivo studies.Article Citation - WoS: 653Citation - Scopus: 739Flow Cytometry: Basic Principles and Applications(Taylor & Francis Ltd, 2016-01-14) Adan, Aysun; Alizada, Gunel; Kiraz, Yagmur; Baran, Yusuf; Nalbant, AytenFlow cytometry is a sophisticated instrument measuring multiple physical characteristics of a single cell such as size and granularity simultaneously as the cell flows in suspension through a measuring device. Its working depends on the light scattering features of the cells under investigation, which may be derived from dyes or monoclonal antibodies targeting either extracellular molecules located on the surface or intracellular molecules inside the cell. This approach makes flow cytometry a powerful tool for detailed analysis of complex populations in a short period of time. This review covers the general principles and selected applications of flow cytometry such as immunophenotyping of peripheral blood cells, analysis of apoptosis and detection of cytokines. Additionally, this report provides a basic understanding of flow cytometry technology essential for all users as well as the methods used to analyze and interpret the data. Moreover, recent progresses in flow cytometry have been discussed in order to give an opinion about the future importance of this technology.Article Citation - WoS: 40Citation - Scopus: 49Fisetin and Hesperetin Induced Apoptosis and Cell Cycle Arrest in Chronic Myeloid Leukemia Cells Accompanied by Modulation of Cellular Signaling(Sage Publications Ltd, 2015-09-25) Adan, Aysun; Baran, YusufFisetin and hesperetin, naturally occurring flavonoids, have been reported as novel antioxidants with chemopreventive/chemotherapeutic potential against various types of cancer. However, their mechanism of action in CML is still unknown. This particular study aims to evaluate the therapeutic potentials of fisetin and hesperetin and their effects on cell proliferation, apoptosis, and cell cycle progression in human K562 CML cells. The results indicated that fisetin and hesperetin inhibited cell proliferation and triggered programmed cell death in these cells. The latter was confirmed by mitochondrial membrane depolarization and an increase in caspase-3 activation. In addition to that, we have detected S and G2/Mcell cycle arrests and G0/G1 arrest upon fisetin and hesperetin treatment, respectively. To identify the altered genes and genetic networks in response to fisetin and hesperetin, whole-genome microarray analysis was performed. The microarray gene profiling analysis revealed some important signaling pathways including JAK/STAT pathway, KIT receptor signaling, and growth hormone receptor signaling that were altered upon fisetin and hesperetin treatment. Moreover, microarray data suggested potential candidate genes for targeted CML therapy. Fisetin and hesperetin significantly modulated the expression of genes involved in cell proliferation and division, apoptosis, cell cycle regulation, and other significant cellular processes such as replication, transcription, and translation. In conclusion, our results suggest that fisetin and hesperetin as potential natural agents for CML therapy.Article Citation - WoS: 8Citation - Scopus: 9Emerging DNA Methylome Targets in FLT3-ITD Acute Myeloid Leukemia: Combination Therapy With Clinically Approved FLT3 Inhibitors(Springer, 2024-05-02) Tecik, Melisa; Adan, AysunThe internal tandem duplication (ITD) mutation of the FMS-like receptor tyrosine kinase 3 (FLT3-ITD) is the most common mutation observed in approximately 30% of acute myeloid leukemia (AML) patients. It represents poor prognosis due to continuous activation of downstream growth-promoting signaling pathways such as STAT5 and PI3K/AKT. Hence, FLT3 is considered an attractive druggable target; selective small FLT3 inhibitors (FLT3Is), such as midostaurin and quizartinib, have been clinically approved. However, patients possess generally poor remission rates and acquired resistance when FLT3I used alone. Various factors in patients could cause these adverse effects including altered epigenetic regulation, causing mainly abnormal gene expression patterns. Epigenetic modifications are required for hematopoietic stem cell (HSC) self-renewal and differentiation; however, critical driver mutations have been identified in genes controlling DNA methylation (such as DNMT3A, TET2, IDH1/2). These regulators cause leukemia pathogenesis and affect disease diagnosis and prognosis when they co-occur with FLT3-ITD mutation. Therefore, understanding the role of different epigenetic alterations in FLT3-ITD AML pathogenesis and how they modulate FLT3I's activity is important to rationalize combinational treatment approaches including FLT3Is and modulators of methylation regulators or pathways. Data from ongoing pre-clinical and clinical studies will further precisely define the potential use of epigenetic therapy together with FLT3Is especially after characterized patients' mutational status in terms of FLT3 and DNA methlome regulators.Article Citation - WoS: 13Citation - Scopus: 17Effects of Cell-Mediated Osteoprotegerin Gene Transfer and Mesenchymal Stem Cell Applications on Orthodontically Induced Root Resorption of Rat Teeth(Oxford Univ Press, 2016-10-12) Amuk, Nisa Gul; Kurt, Gokmen; Baran, Yusuf; Seyrantepe, Volkan; Yandim, Melis Kartal; Adan, Aysun; Sonmez, Mehmet FatihAim: The aim of this study is to evaluate and compare therapeutic effects of mesenchymal stem cell (MSCs) and osteoprotegerin (OPG) gene transfer applications on inhibition and/or repair of orthodontically induced inflammatory root resorption (OIIRR). Materials and methods: Thirty Wistar rats were divided into four groups as untreated group (negative control), treated with orthodontic appliance group (positive control), MSCs injection group, and OPG transfected MSCs [gene therapy (GT) group]. About 100 g of orthodontic force was applied to upper first molar teeth of rats for 14 days. MSCs and transfected MSC injections were performed at 1st, 6th, and 11th days to the MSC and GT group rats. At the end of experiment, upper first molar teeth were prepared for genetical, scanning electron microscopy (SEM), fluorescent microscopy, and haematoxylin eosin-tartrate resistant acid phosphatase staining histological analyses. Number of total cells, number of osteoclastic cells, number of resorption lacunae, resorption area ratio, SEM resorption ratio, OPG, RANKL, Cox-2 gene expression levels at the periodontal ligament (PDL) were calculated. Paired t-test, Kruskal-Wallis, and chi-square tests were performed. Results: Transferred MSCs showed marked fluorescence in PDL. The results revealed that number of osteoclastic cells, resorption lacunae, resorption area ratio, RANKL, and Cox-2 were reduced after single MSC injections significantly (P < 0.05). GT group showed the lowest number of osteoclastic cells (P < 0.01), number of resorption lacunae, resorption area ratio, and highest OPG expression (P < 0.001). Conclusions: Taken together all these results, MSCs and GT showed marked inhibition and/or repair effects on OIIRR during orthodontic treatment on rats.