title: With no interaction, knockdown of Apollon and MDR1 reverse the multidrug resistance of human chronic myelogenous leukemia K562/ADM cells.
abstract: Chemotherapy is the main treatment method for patients with chronic myeloid leukemia (CML) and has achieved marked results. However, the acquisition of multidrug resistance (MDR) has seriously affected the quality of life and survival rate of patients. The overexpression of the inhibitors of apoptosis proteins (IAPs) and the adenosine triphosphate (ATP)-dependent binding cassette (ABC) transporters are the two main causes of MDR. Apollon and MDR1 are the most important and representative members, respectively, among the IAPs and ABC transporters. In the present study, we investigated the role of Apollon and MDR1 in chemotherapy resistance and their mechanism of interaction. We respectively knocked down the expression of Apollon and MDR1 using short hairpin RNA (shRNA) in adriamycin (ADM) resistant human CML K562 cells and examined the drug sensitivity, the consequences with regard to ADM accumulation and the alterations in the expression of Apollon and MDR1. The expression levels of Apollon and MDR1 mRNA were higher in the K562/ADM cells compared with the parental K562 cells as determined by reverse transcription‑polymerase chain reaction (RT-PCR). The plasmids of Apollon and MDR1 shRNA were respectively stably transfected into K562/ADM cells using Lipofectamine 2000. The transfection efficiency was detected by fluorescence microscopy. Cell Counting Kit-8 (CCK-8) assay revealed that Apollon or MDR1 knockdown significantly increased the chemosensitivity of the K562/ADM cells to ADM. Flow cytometric assay revealed that K562/ADM/shMDR1 cells exhibited a significantly increased intracellular accumulation of ADM, and that changes were not found in the K562/ADM/shApollon cells. Compared with the parental K562/ADM cells, a significantly decreased expression of Apollon mRNA and protein was determined in the K562/ADM/shApollon cells without affecting the expression of MDR1 as determined by RT-PCR and western blotting. Likewise, the expression levels of MDR1 mRNA and protein also markedly downregulated in the K562/ADM/shMDR1 cells had no effect on Apollon expression. Collectively, our findings demonstrated, for the first time, that downregulation of Apollon or MDR1 through stable transfection with the Apollon- or MDR1-targeting shRNA induced MDR reversal through respective inhibition of Apollon or MDR1 expression and function. However, the reversal mechanism of Apollon and MDR1 revealed no direct interaction with each other.
authors.affiliation: Department of Pediatrics, The Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong 256603, P.R. China.
authors.forename: Jie-Ru
authors.initials: JR
authors.lastname: Chen
authors.affiliation: Department of Pediatrics, The Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong 256603, P.R. China.
authors.forename: Xiu-Hong
authors.initials: XH
authors.lastname: Jia
authors.affiliation: Department of Pediatrics, The Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong 256603, P.R. China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Pediatrics, The Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong 256603, P.R. China.
authors.forename: Ying-Jie
authors.initials: YJ
authors.lastname: Yi
authors.affiliation: Department of Biochemistry and Molecular Biology, Key Laboratory of Tumour Molecular Biology, Binzhou Medical University, Yantai, Shandong 264003, P.R. China.
authors.forename: You-Jie
authors.initials: YJ
authors.lastname: Li
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics; D004317:Doxorubicin / Q000493:pharmacokinetics / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D015316:Genetic Therapy / Q000379:methods; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics*; D020014:K562 Cells; D034741:RNA, Small Interfering
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; C401541:BIRC6 protein, human; D051034:Inhibitor of Apoptosis Proteins; D034741:RNA, Small Interfering; D004317:Doxorubicin