title: Reversal of MDR1/P-glycoprotein-mediated multidrug resistance by vector-based RNA interference in vitro and in vivo.
abstract: Overexpression of P-glycoprotein (P-gp) encoded by MDR1 gene in cancer cells results in multidrug resistance (MDR) to structurally and mechanistically different chemotherapeutic drugs, which is a major cause for cancer chemotherapy failures to cancer patients. Recently, there were several reports showing that expression of siRNAs targeting MDR1 gene is able to reverse the P-gp mediated MDR, however, the in vivo reversal effects for MDR have still not been identified. We developed a novel MDR reversal system using RNA interference technique in human epidermoid carcinoma KBv200 cells. The stably expressing MDR1 shRNA cells (KBv200/MDR1sh) were established with transfection of vector pEGFPC2-H1-MDR1shDNA containing MDR1-V siRNA expression cassette, and we found that more than 90% of MDR1 mRNA and P-gp were reduced. KBv200/MDR1sh cells simultaneously showed stably expressing EGFP and kept low MDR1 expression beyond ten passages. Compared KBv200/MDR1sh cells with KBv200 cells, resistance to vincristine and doxorubicin decreased from 62.4-fold to 10.5-fold and from 74.5-fold to 9.5-fold respectively, and intracellular doxorubicin accumulation enhanced from 0.30 +/- 0.08 nmoles/10(6) cells to 0.86 +/- 0.16 nmoles/10(6) cells, and the fluorescence intensity of intracellular Rhodamine 123 accumulation increased from 3.58 +/- 1.63/10(6) cells to 13.96 +/- 3.07/10(6) cells. In the nude mice xenografts, vincristine (0.2 mg/kg of body weight) inhibited the growth of KBv200/MDR1sh solid tumors by 42.0%, but the same dose of vincristine didn't inhibit the growth of KBv200 solid tumors significantly. These results suggest that administration of RNAi targeted MDR1 gene can effectively reverse MDR both in vitro and in vivo models.
authors.affiliation: State Key Laboratory for Oncology in South China, Cancer Center, Sun Yat-SenUniversity, Guangzhou, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Shi
authors.forename: Yong-ju
authors.initials: YJ
authors.lastname: Liang
authors.forename: Zhe-sheng
authors.initials: ZS
authors.lastname: Chen
authors.forename: Xiu-wen
authors.initials: XW
authors.lastname: Wang
authors.forename: Xiao-hong
authors.initials: XH
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Ding
authors.forename: Li-ming
authors.initials: LM
authors.lastname: Chen
authors.forename: Xiao-ping
authors.initials: XP
authors.lastname: Yang
authors.forename: Li-wu
authors.initials: LW
authors.lastname: Fu
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000235:genetics; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D019450:Genes, MDR / Q000235:genetics*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D051379:Mice; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic / Q000235:genetics; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000096:biosynthesis / Q000235:genetics; D014750:Vincristine / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D034741:RNA, Small Interfering; D014750:Vincristine