title: Chemotherapeutic sensitization of leptomycin B resistant lung cancer cells by pretreatment with doxorubicin.
abstract: The development of novel targeted therapies has become an important research focus for lung cancer treatment. Our previous study has shown leptomycin B (LMB) significantly inhibited proliferation of lung cancer cells; however, p53 wild type lung cancer cells were resistant to LMB. Therefore, the objective of this study was to develop and evaluate a novel therapeutic strategy to sensitize LMB-resistant lung cancer cells by combining LMB and doxorubicin (DOX). Among the different treatment regimens, pretreatment with DOX (pre-DOX) and subsequent treatment with LMB to A549 cells significantly decreased the 50% inhibitory concentration (IC50) as compared to that of LMB alone (4.4 nM vs. 10.6 nM, P<0.05). Analysis of cell cycle and apoptosis by flow cytometry further confirmed the cytotoxic data. To investigate molecular mechanisms for this drug combination effects, p53 pathways were analyzed by Western blot, and nuclear proteome was evaluated by two dimensional-difference gel electrophoresis (2D-DIGE) and mass spectrometry. In comparison with control groups, the levels of p53, phospho-p53 (ser15), and p21 proteins were significantly increased while phospho-p53 (Thr55) and survivin were significantly decreased after treatments of pre-DOX and LMB (P<0.05). The 2D-DIGE/MS analysis identified that sequestosome 1 (SQSTM1/p62) had a significant increase in pre-DOX and LMB-treated cells (P<0.05). In conclusion, our results suggest that drug-resistant lung cancer cells with p53 wild type could be sensitized to cell death by scheduled combination treatment of DOX and LMB through activating and restoring p53 as well as potentially other signaling pathway(s) involving sequestosome 1.
authors.affiliation: Department of Environmental Toxicology, The Institute of Environmental and Human Health, Texas Tech University, Lubbock, Texas, United States of America.
authors.forename: Chuanwen
authors.initials: C
authors.lastname: Lu
authors.forename: Changxia
authors.initials: C
authors.lastname: Shao
authors.forename: Everardo
authors.initials: E
authors.lastname: Cobos
authors.forename: Kamaleshwar P
authors.initials: KP
authors.lastname: Singh
authors.forename: Weimin
authors.initials: W
authors.lastname: Gao
mesh_terms: D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology* / Q000633:toxicity; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology / Q000633:toxicity; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D000077022:Survivin; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C107489:BIRC5 protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D005231:Fatty Acids, Unsaturated; D051034:Inhibitor of Apoptosis Proteins; D009687:Nuclear Proteins; D000077022:Survivin; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin; C038753:leptomycin B