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    Apoptotic effect of essential oils from cultured and wild form of Origanum acutidens (Hand.-Mazz.) Ietswaart. (Lamiaceae) on lung cancer cells (A549)
    (Wiley, 2018) Özkan, Aysun; Erdoğan, Ayşe; Dülgeroğlu, Canan
    [No abstract available]
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    Cetuximab and epirubicin HCl-combined application as a possibility to treat both parental and epirubicin HCl-resistant liver cancer cells
    (Akademiai Kiado Zrt, 2019) Erdoğan, Ayşe; Özkan, Aysun
    Background and aims: Targeted chemotherapeutics such as cetuximab can cause many side effects such as skin toxicity when used in high concentrations. In addition, cancer cells can develop resistance to some of the anticancer agents during treatment. The lack of the desired success in chemotherapy and the development of resistance to chemotherapeutics, such as epirubicin HCl, suggest that there is a need for combined therapies. The combination of targeted chemotherapeutics and conventional chemotherapy drugs may lead to the emergence of new strategies in the treatment of cancer. In this study, cytotoxic, antiproliferative, cell cycle inhibitive, oxidative stress generation, and apoptotic effects and effect mechanisms of cetuximab alone and together with epirubicin HCl on parental liver cancer cells (P-Hep G2) and epirubicin HCl-resistant liver cancer cells (R-Hep G2) were investigated. Materials: Cytotoxic effects of cetuximab alone and with epirubicin-HCl on cells were determined by Cell Titer-Blue (R) Cell Viability and Lactate Dehydrogenase Activity tests. Cell cycle distributions and apoptosis were detected by reverse transcription polymerase chain reaction (RT-PCR). Results: Cetuximab with epirubicin HCl treatment increased the cytotoxic effect on both cells. Caspase-3/7 activity increased 3 and 1.5 times in comparison with control group in P-Hep G2 and R-Hep G2 cells, respectively, after treating with cetuximab alone, whereas the increase was found to be approximately 4.7 and 2.5 times when cetuximab was treated with epirubicin HCl in P-Hep G2 and R-Hep G2 cells, respectively. Both cetuximab alone and together with epirubicin HCl treatments caused increases in Bax/Bcl-2 ratio in both cells. Discussion: Treatment of cetuximab with epirubicin HCl to P-Hep G2 and R-Hep G2 cells was found to be more effective in cytotoxic effect and inducing apoptosis comparison to cetuximab alone treatment. In addition, combination treatment showed different effects on pro-apoptotic/anti-apoptotic genes expression according to cells drug resistance properties.
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    Enhanced anticancer effect of cetuximab combined with stabilized silver ion solution in EGFR-positive lung cancer cells
    (2019) Erdoğan, Ayşe; Özkan, Aysun; Özkan, Ödül; Manguoğlu, Esra; Kiraz, Nadir
    Background: Cytotoxic, antiproliferative, cell cycle inhibi- tive, oxidative and apoptotic effects of cetuximab [anti- body for epidermal growth factor receptor (EGFR)] alone and together with stabilized silver ion solution (St-Ag) on P-H1299, R-H1299, A-431 and A-549 cells were investigated. Materials and methods: Cytotoxic effects of cetuximab alone and together with St-Ag on cells were determined by Cell Titer-Blue® Cell Viability and Lactate Dehydrogenase Activ- ity tests. Cell cycle distributions and apoptosis were detected by reverse transcription polymerase chain reaction (RT-PCR). Results: St-Ag enhanced cetuximab cytotoxic effect on all cells. LDH activity, as a result of cell death, was found the highest level at treatment of cetuximab with St-Ag in all cells. Both treatment increased caspase-3/7 activity which is apoptotic enzyme was found higher in A-549 cells than other cells. Also, treatment of cetuximab with St-Ag caused increasing Bax/Bcl-2 ratio in all cells. Cetuximab with St-Ag treatment increased glutathione peroxidase activity in all cells generating oxidative stress. Proliferating Cell Nuclear Antigen (PCNA), topoisomerase II-alpha (except R-H1299), cyclin D1 and D2 genes expression were decreased in all cells which explain the cell cycle inhibition effect. Conclusion: These findings suggest that treatment of cetuximab combined with St-Ag exhibit more carcinogen- esis reducing potential than cetuximab alone.
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    Evaluation of the cytotoxic and membrane damaging effects of mountain tea (Sideritis stricta Boiss & Heldr.) essential oil on parental and epirubicin-HCl resistant H1299 cells
    (2018) Erdoğan, Ayşe; Özkan, Aysun; Ünal, Orhan; Dülgeroğlu, Canan
    Purpose: In this study, we evaluated Sideritis stricta (S. stricta), as potential-oxidative agents against parental and epirubicin-HCl resistant H1299 cells. Material and Methods: Oxidative stress biomarkers such as malondialdehyde level determined in cell lysates. Assessment of cell viability was made by CellTiter-Blue® Cell Viability Assay and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT) assay after 20-600 ?g/mL essential oil concentrations treated to parental and epirubicin-HCl (drug) resistant H1299 cells for 24, 48 and 72 h. Malondialdehyde levels were assayed for determining the membrane damaging effects. Results: Parental H1299 cells were found to be more sensitive to cytotoxic effect of the essential oil. Essential oil showed cytotoxic and more selective effects depend on time and concentration. Essential oil caused increasing malondialdehyde level on both parental and drug resistant H1299 cells. The highest concentration of the essential oil (IC70) treatment caused the highest membrane damage on both parental and drug resistant H1299 cells. Conclusions: Parental and epirubicin-HCl resistant H1299 cells showed different cellular response against potential antitumour and pro-oxidative effects of essential oil.