title: Targeting glucosylceramide synthase downregulates expression of the multidrug resistance gene MDR1 and sensitizes breast carcinoma cells to anticancer drugs.
abstract: Drug resistance in breast cancer remains a major cause for the failure of chemotherapy. Glucosylceramide synthase (GCS) plays an important role in multidrug resistance (MDR) in breast cancer. P-glycoprotein (P-gp) also confers a cross-resistance of many unrelated drugs. In this study, we studied the MDR effect and potential mechanisms of breast cancer after constructing permanent breast cancer cell lines with GCS knockout by using recombinant vectors targeting GCS (pSUPER-GCSshRNAs). The GCSshRNA stably transfected cells were successfully established and significant lower levels of GCS mRNA and protein expression were confirmed. In in vitro experiments, the GCSshRNA stably transfected cells showed a significantly reduced level of MDR1 and P-gp expression and decreased drug efflux ability. Reduced level of GCS expression conveyed a significant reversal of drug resistance by MTT assay and increased caspase-3 activity. In in vivo experiments by using nude mice with xenograft tumors, a significant inhibition of tumor growth was observed after comparing with the control group. Furthermore, enhanced response of chemotherapy was acquired by reduced expression of GCS as well as MDR1 in vivo. In conclusion, GCSshRNA could efficiently suppress GCS and MDR1 expression in vitro and in vivo and these findings may be used as one of the methods to reverse MDR in breast cancer.
authors.affiliation: Department of Pathology, School of Medicine, Shandong University, Jinan 250012, People's Republic of China. yanlinsunny@hotmail.com
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Sun
authors.forename: Tingguo
authors.initials: T
authors.lastname: Zhang
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.forename: Bin
authors.initials: B
authors.lastname: Meng
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Gao
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Jianping
authors.initials: J
authors.lastname: Zhang
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Wu
authors.forename: Wenxin
authors.initials: W
authors.lastname: Zheng
authors.forename: Gengyin
authors.initials: G
authors.lastname: Zhou
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors*; D000818:Animals; D001943:Breast Neoplasms / Q000188:drug therapy*; D045744:Cell Line, Tumor; D018432:Drug Resistance, Multiple / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D034622:RNA Interference; D023041:Xenograft Model Antitumor Assays
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D005964:Glucosyltransferases; C023246:ceramide glucosyltransferase