title: Novel gene P28GANK confers multidrug resistance by modulating the expression of MDR-1, Bcl-2 and Bax in osteosarcoma cells.
abstract: As previously reported, a novel gene P28GANK conferred a multidrug resistant phenotype in gastric cancer cells. The aim of this study was to explore the role of P28GANK in the development of multidrug resistance (MDR) in osteosarcoma cells. P28GANK gene was found to be overexpressed at the mRNA level and the protein level in a cisplatin induced MDR osteosarcoma cell line Saos-2/CDDP compared to its parent cell line Saos-2. Here, we transfected the osteosarcoma cell line Saos-2 with eukaryotic expression vector of P28GANK. In vitro drug sensitivity assay suggested that Saos-2-P28GANK cells conferred resistance to both P-glycoprotein (P-gp)-related and P-gp-nonrelated drugs. Blocking P28GANK expression in MDR osteosarcoma cells Saos-2/CDDP by P28GANK-specific small interfering RNA (siRNA) increased the cell sensitivity to various chemotherapeutic drugs. Flow cytometry examination suggested that P28GANK gene expression could suppress Adriamycin-induced apoptosis accompanied by decreased accumulation and increased release of Adriamycin. Semiquantitative RT-PCR, Western blot and Luciferase reporter assay suggested that P28GANK gene could significantly up-regulate the expression of MDR-1 and Bcl-2, transcription of the MDR-1 gene and down-regulate the expression of Bax. In addition, inhibition of P28GANK expression by RNA interference or P-gp inhibition could partially reverse P28GANK-mediated MDR. Taken together, our findings suggest that down-regulation of P28GANK gene expression could sensitize osteosarcoma cells to chemotherapeutic drugs by down-regulation of the MDR-1 and Bcl-2 and up-regulation of Bax gene expression, without altering the glutathione S-transferase activity, or intracellular glutathione content in osteosarcoma cells. Further study on biological function of P28GANK may be helpful for understanding MDR mechanism of osteosarcoma and developing a strategy for osteosarcoma treatment.
authors.affiliation: Department of Orthopedic Oncology, Tianjin Cancer Institute, Hospital, Tianjin Medical University, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Huanhuxi Road, Hexi District, Tianjin, 300060 China. guowengwang@yahoo.cn
authors.forename: Guowen
authors.initials: G
authors.lastname: Wang
authors.forename: Jiesheng
authors.initials: J
authors.lastname: Rong
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhou
authors.forename: Jian
authors.initials: J
authors.lastname: Duo
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D017209:Apoptosis / Q000235:genetics; D001859:Bone Neoplasms / Q000235:genetics*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D019254:Genes, bcl-2; D006801:Humans; D012516:Osteosarcoma / Q000235:genetics*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000502:physiology*; D061988:Proteasome Inhibitors; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D015854:Up-Regulation; D014700:Verapamil / Q000494:pharmacology; D051028:bcl-2-Associated X Protein / Q000235:genetics*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C494826:BAX protein, human; C403591:PSMD10 protein, human; D061988:Proteasome Inhibitors; D011518:Proto-Oncogene Proteins; D051028:bcl-2-Associated X Protein; D014700:Verapamil; D046988:Proteasome Endopeptidase Complex