Person: YALÇIN, AHMET SUHA
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YALÇIN
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AHMET SUHA
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Publication Open Access Synergistic Effects of Methotrexate and Suberoylanilide Hydroxamic Acid in Triggering Apoptosis of Chronic Myeloid Leukemia Cells(AKAD DOKTORLAR YAYINEVI, 2015-03-30) YALÇIN, AHMET SUHA; Altundag, Ergul M.; Yilmaz, Ayse M.; Corek, Ceyda; Yalcin, A. Suha; Taga, Yavuz; Kocturk, SemraIn this study, we have investigated the effects of suberoylanilide hydroxamic acid (SAHA) against chronic myeloid leukemia (CML) cells in combination studies with methotrexate (MTX), which is a dihydrofolate reductase inhibitor used in combination therapy with other agents or alone. Combination of synergistic ratios of MTX and SAHA led to apoptotic cell death of CML cells via PARR cleavage, cytochrome c release and ROS increase in vitro. We suggest that combination of MD( and SAHA may minimize the toxicity and side effects of SAHA treatment, thus providing lower amounts of each drug in CML treatment.Publication Open Access Quercetin-Induced Cell Death in Human Papillary Thyroid Cancer (B-CPAP) Cells(HINDAWI LTD, 2016) YALÇIN, AHMET SUHA; Altundag, Ergul Mutlu; Kasaci, Tolga; Yilmaz, Ayse Mine; Karademir, Betul; Kocturk, Semra; Taga, Yavuz; Yalcin, A. SuhaIn this study, we have investigated the antiproliferative effect of quercetin on human papillary thyroid cancer cells and determined the apoptotic mechanisms underlying its actions. We have used different concentrations of quercetin to induce apoptosis and measured cell viability. Apoptosis and cell cycle analysis was determined by flow cytometry using Annexin V and propidium iodide. Finally, we have measured changes in caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP) protein expression levels as hallmarks of apoptosis and Hsp90 protein expression level as a marker of proteasome activity in treated and control cells. Quercetin treatment of human papillary thyroid cancer cells resulted in decreased cell proliferation and increased rate of apoptosis by caspase activation. Furthermore, it was demonstrated that quercetin induces cancer cell apoptosis by downregulating the levels of Hsp90. In conclusion, we have shown that quercetin induces downregulation of Hsp90 expression that may be involved in the decrease of chymotrypsin-like proteasome activity which, in order, induces inhibition of growth and causes cell death in thyroid cancer cells. Thus, quercetin appears to be a promising candidate drug for Hsp90 downregulation and apoptosis of thyroid cancer cells.Publication Metadata only Synergistic Induction of Apoptosis by Quercetin and Curcumin in Chronic Myeloid Leukemia (K562) Cells(ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, 2018) YALÇIN, AHMET SUHA; Altundag, Ergul Mutlu; Yilmaz, Ayse Mine; Kocturk, Semra; Taga, Yavuz; Yalcin, A. SuhaChronic myeloid leukemia is a major hematopoietic malignancy characterized by expansion of myeloid cells. In this study, we have investigated whether quercetin, curcumin and their combination induce apoptosis and inhibit growth of K562 cells. We have observed that quercetin and curcumin combination induced apoptosis accompanied by increased ROS and decreased GSH levels as well as loss of mitochondrial membrane potential. Our mRNA and protein expression results suggested that cytochrome c was released from mitochondria causing PARP and caspase-9 cleavages, the hallmarks of mitochondrial apoptotic pathway. We believe that triggering of apoptosis is mostly via mitochondrial pathway and ROS generation may induce impairment of mitochondrial membrane potential. The use of quercetin and curcumin combination potentiates individual apoptotic effects of the polyphenols and reduces their effective dose thereby preventing potential toxic effects on normal cells. Additional preclinical studies and clinical trials are certainly required to further validate their usefulness as potent anticancer agents.