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    Exploring a natural MDR reversal agent: Potential of medicinal food supplement Nerium oleander leaf distillate
    (2013) Kars M.D.; Gündüz U.; Üney K.; Baş A.L.
    Objective: To investigate the molecular effects of Nerium oleander leaf distillate on paclitaxel and vincristine resistant (MCF-7/Pac and MCF-7/Vinc) cells and sensitive (MCF-7/S) cell lines. Methods: Nerium oleander (N. oleander) leaf extract was obtained by hydrodistillation method. The toxicological effects of N. oleander distillate, previously suggested as medicinal food supplement, on drug resistant cells were evaluated by XTT tests. MDR modulation potential of the plant material was evaluated by flow cytometry and fluorescent microscopy. Paclitaxel and vincristine were applied to the sublines in combination with N. oleander distillate. Results: Fractional inhibitory indices show that N. oleander distillate did not increase the antiproliferative effects of anticancer drugs. N. oleander treatment in to MCF-7/Pac and MCF-7/Vinc did not inhibit P-gp activity and MDR1 gene expression level. Conclusions: As a result it may be suggested that although N. oleander distillate has some medicinal effects as food supplement it may not be suitable as an MDR modulator for drug resistant breast cancer cells. © 2013 Asian Pacific Tropical Biomedical Magazine.
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    Fomes fomentarius and tricholoma anatolicum (Agaricomycetes) extracts exhibit significant multiple drug-resistant modulation activity in drug-resistant breast cancer cells
    (Begell House Inc., 2020) Doğan H.H.; Kars M.D.; Özdemir Ö.; Gündüz U.
    Multiple drug resistance is one of the main problems that hinder successful cancer chemotherapy. Investigations on the development of effective chemotherapeutic agents and drug resistance inhibitors motivate studies on the effects of natural compounds on drug-resistant cancer cells. For this purpose, aqueous, methanol, and ethanol extracts of Fomes fomentarius and Tricholoma anatolicum were prepared. The extracts were evaluated to assess their anticancer and multiple drug resistance modulation activities. Cytotoxic effects of F. fomentarius and T. anatolicum extracts on paclitaxel and vincristine resistant P-glycoprotein over-expressing MCF-7 cell lines were investigated by cytotoxicity test (XTT). P-glycoprotein reversing ability and MDR modulation effects of the extracts were determined by flow cytometry through Rhodamine 123 exclusion assay. Furthermore, 11 phenolic compounds in the extracts were characterized by HPLC. As a result of the cytotoxicity assay, IC50 values of the extracts for MCF-7/Vinc were between 1.08 and 1.80 mg/ mL, and IC50 values for MCF-7/Pac were found between 1.11 and 2.83 mg/mL. Strikingly, methanol extract of F. fomentarius and ethanol extract of T. anatolicum have potential value to become MDR reversing agents for drug-resistant breast cancer cells. © 2020 by Begell House.
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    Two different docetaxel resistant MCF-7 sublines exhibited different gene expression pattern
    (Kluwer Academic Publishers, 2012) İşeri O.D.; Kars M.D.; Gündüz U.
    The objective of the present study was to investigate gene expression pattern of two docetaxel resistant MCF-7 breast carcinoma sublines step wisely selected in 30 and 120 nM docetaxel. Cell proliferation assay was performed in order to demonstrate development of docetaxel resistance. cDNA microarray analysis was performed using Affymetrix® Human Genome U133 Plus 2.0 Arrays in duplicate experiments. Quantitative and semi-quantitative gene expression analysis was also performed to confirm gene expression analysis for selected genes. XTT results demonstrated that 30 (MCF-7/30nM DOC) and 120 nM (MCF-7/120nM DOC) docetaxel selected cells were 13-and 47-fold resistant, respectively. cDNA microarray analysis demonstrated that expression profiles of MCF-7 and MCF-7/30nM DOC were more similar to each other where expression profile of MCF-7/ 120nM DOC was different as examined by line graphs and scatter plots. 2,837 and 4,036 genes were significantly altered in 30 and 120 nM docetaxel resistant sublines, respectively. Among these, 849 genes were altered in common in two docetaxel resistant sublines. Antiapoptotic gene expression (e.g., Bcl-2 and APRIL) were noticeably altered in MCF-7/30nM DOC. However, docetaxel resistance in MCF-7/120nM DOC were more complicated with the involvement of ECM related gene expression, cytokine and growth factor signaling, ROS metabolism and EMT related gene expression together with higher level of MDR1 expression. Expression profiles in 30 and 120 nM docetaxel resistant sublines changed gradually with increasing resistance index. Drug resistance development seems to be step wise event in MCF-7 cells. © Springer Science+Business Media B.V. 2011.