title: Involvement of microRNA-451 in resistance of the MCF-7 breast cancer cells to chemotherapeutic drug doxorubicin.
abstract: Many chemotherapy regiments are successfully used to treat breast cancer; however, often breast cancer cells develop drug resistance that usually leads to a relapse and worsening of prognosis. We have shown recently that epigenetic changes such as DNA methylation and histone modifications play an important role in breast cancer cell resistance to chemotherapeutic agents. Another mechanism of gene expression control is mediated via the function of small regulatory RNA, particularly microRNA (miRNA); its role in cancer cell drug resistance still remains unexplored. In the present study, we investigated the role of miRNA in the resistance of human MCF-7 breast adenocarcinoma cells to doxorubicin (DOX). Here, we for the first time show that DOX-resistant MCF-7 cells (MCF-7/DOX) exhibit a considerable dysregulation of the miRNAome profile and altered expression of miRNA processing enzymes Dicer and Argonaute 2. The mechanistic link of miRNAome deregulation and the multidrug-resistant phenotype of MCF-7/DOX cells was evidenced by a remarkable correlation between specific miRNA expression and corresponding changes in protein levels of their targets, specifically those ones that have a documented role in cancer drug resistance. Furthermore, we show that microRNA-451 regulates the expression of multidrug resistance 1 gene. More importantly, transfection of the MCF-7/DOX-resistant cells with microRNA-451 resulted in the increased sensitivity of cells to DOX, indicating that correction of altered expression of miRNA may have significant implications for therapeutic strategies aiming to overcome cancer cell resistance.
authors.affiliation: Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4. olga.kovalchuk@uleth.ca
authors.forename: Olga
authors.initials: O
authors.lastname: Kovalchuk
authors.forename: Jody
authors.initials: J
authors.lastname: Filkowski
authors.forename: James
authors.initials: J
authors.lastname: Meservy
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Ilnytskyy
authors.forename: Volodymyr P
authors.initials: VP
authors.lastname: Tryndyak
authors.forename: Vasyl' F
authors.initials: VF
authors.lastname: Chekhun
authors.forename: Igor P
authors.initials: IP
authors.lastname: Pogribny
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D060565:Argonaute Proteins; D001483:Base Sequence; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D043244:Ribonuclease III / Q000378:metabolism
chemical_list: C466422:AGO2 protein, human; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D060565:Argonaute Proteins; D015852:Eukaryotic Initiation Factor-2; C531201:MIRN451 microRNA, human; D035683:MicroRNAs; D004317:Doxorubicin; D043244:Ribonuclease III