title: Down-regulation of ICBP90 contributes to doxorubicin resistance.
abstract: Acquired resistance to doxorubicin has become a serious obstacle in breast cancer treatment. The underlying mechanism responsible for this has not been completely elucidated. In this study, a doxorubicin-resistant MCF-7/Dox cell was developed to mimic the occurrence of acquired doxorubicin resistance. We next contrasted the expression profiles of ICBP90 and Topo IIα and tumor cell growth of different breast cancer cell lines to doxorubicin. Decreased expression levels of ICBP90 and Topo IIα were found in doxorubicin-resistant cells. To examine its function in chemoresistance, RNA interference (RNAi) and forskolin stimulation experiments further demonstrated that ICBP90 and Topo IIα were involved in the proliferation of cells that had acquired doxorubicin resistance. In MCF-7/Dox and ICBP90-siRNA cells, the cell growth wasn't inhibited by doxorubicin and preferentially arrested in G1 phase. However, after forskolin increased the Topo IIα expression, these breast cancer cells were again found to be inhibited by doxorubicin. Further, immunohistochemical assay breast cancer patients accepted EFC regimen showed ICBP90 was significantly associated with tumor cell proliferation, locally advanced disease and Topo IIα expression. In conclusion, down-regulation of ICBP90 induced the descended expression of Topo IIα protein which is the target enzyme of doxorubicin.
authors.affiliation: Department of Medical Oncology, The Third Hospital of Harbin Medical University, Harbin, China.
authors.forename: Jingxuan
authors.initials: J
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Song
authors.forename: Shanqi
authors.initials: S
authors.lastname: Xu
authors.forename: Qingyuan
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yulian
authors.initials: Y
authors.lastname: Li
authors.forename: Dabei
authors.initials: D
authors.lastname: Tang
authors.forename: Shi
authors.initials: S
authors.lastname: Jin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D014408:Biomarkers, Tumor / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics*; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D016193:G1 Phase / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D055785:Gene Knockdown Techniques; D006801:Humans; D008875:Middle Aged; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D044767:Ubiquitin-Protein Ligases
chemical_list: D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D005576:Colforsin; D004317:Doxorubicin; C406364:UHRF1 protein, human; D044767:Ubiquitin-Protein Ligases; D004250:DNA Topoisomerases, Type II