title: C-Myc participates in β-catenin-mediated drug resistance in A549/DDP lung adenocarcinoma cells.
abstract: The aim of this study was to investigate c-Myc and β-catenin-mediated drug resistance in A549/DDP lung adenocarcinoma cells. Cisplatin sensitivity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) toxicity assay. β-Catenin and c-Myc protein expression following cisplatin treatment were determined using western blotting and immunofluorescence. Flow cytometry was performed to detect cell cycle and apoptosis in A549, A549/DDP, and c-Myc small interfering RNA (siRNA)-transfected A549/DDP cells before and after treatment with different doses of cisplatin. The median inhibitory concentration (IC50 ) in cisplatin-treated A549 and A549/DDP cells was 5.769 ± 0.24 μmol/L and 28.373 ± 0.96 μmol/L, respectively; the cisplatin resistance of A549 cells was about five times that of A549/DDP cells. Endogenous β-catenin and c-Myc expression in A549/DDP cells were higher than that in A549 cells, and were upregulated in A549/DDP cells (p < 0.05) and downregulated in A549 cells after 48 h cisplatin treatment (p < 0.05). β-catenin localization transferred from membrane/cytoplasmic/nuclear to cytoplasmic/nuclear, and c-Myc localization transferred from cytoplasmic/nuclear to nuclear in both cell lines following cisplatin treatment. The rate of apoptosis increased in a dose-dependent manner with cisplatin. After 48-h transfection with c-myc siRNA, A549/DDP cells were blocked in the S phase, and G0/G1-phase cells increased. Simultaneously, the apoptotic rate was increased (p < 0.05) and the IC50 decreased significantly (p < 0.05). C-myc, the downstream target gene of β-catenin, plays an important role in regulating cisplatin resistance in A549/DDP cells. C-Myc siRNA improved the sensitivity of A549/DDP cells to cisplatin.
authors.affiliation: Department of Pathology, The First Affiliated Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, China; Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Chengyao
authors.initials: C
authors.lastname: Xie
authors.forename: Yongqi
authors.initials: Y
authors.lastname: Pan
authors.forename: Fengxia
authors.initials: F
authors.lastname: Hao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Gao
authors.forename: Zan
authors.initials: Z
authors.lastname: Liu
authors.forename: Xiuwei
authors.initials: X
authors.lastname: Zhang
authors.forename: Lingling
authors.initials: L
authors.lastname: Xie
authors.forename: Guiyang
authors.initials: G
authors.lastname: Jiang
authors.forename: Qingchang
authors.initials: Q
authors.lastname: Li
authors.forename: Enhua
authors.initials: E
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma; D000077192:Adenocarcinoma of Lung; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D020128:Inhibitory Concentration 50; D008175:Lung Neoplasms; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000302:isolation & purification; D013778:Tetrazolium Salts; D013844:Thiazoles; D014162:Transfection; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; C495270:CTNNB1 protein, human; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D034741:RNA, Small Interfering; D013778:Tetrazolium Salts; D013844:Thiazoles; D051176:beta Catenin; C022616:thiazolyl blue; D002945:Cisplatin
keywords: C-Myc; drug resistance; lung adenocarcinoma; β-catenin