title: Short-hairpin RNA-mediated Heat shock protein 90 gene silencing inhibits human breast cancer cell growth in vitro and in vivo.
abstract: Hsp90 interacts with proteins that mediate signaling pathways involved in the regulation of essential processes such as proliferation, cell cycle control, angiogenesis and apoptosis. Hsp90 inhibition is therefore an attractive strategy for blocking abnormal pathways that are crucial for cancer cell growth. In the present study, the role of Hsp90 in human breast cancer MCF-7 cells was examined by stably silencing Hsp90 gene expression with an Hsp90-silencing vector (Hsp90-shRNA). RT-PCR and Western blot analyses showed that Hsp90-shRNA specifically and markedly down-regulated Hsp90 mRNA and protein expression. NF-kB and Akt protein levels were down-regulated in Hsp90-shRNA transfected cells, indicating that Hsp90 knockout caused a reduction of survival factors and induced apoptosis. Treatment with Hsp90-shRNA significantly increased apoptotic cell death and caused cell cycle arrest in the G1/S phase in MCF-7 cells, as shown by flow cytometry. Silencing of Hsp90 also reduced cell viability, as determined by MTT assay. In vivo experiments showed that MCF-7 cells stably transfected with Hsp90-shRNA grew slowly in nude mice as compared with control groups. In summary, the Hsp90-shRNA specifically silenced the Hsp90 gene, and inhibited MCF-7 cell growth in vitro and in vivo. Possible molecular mechanisms underlying the effects of Hsp90-shRNA include the degradation of Hsp90 breast cancer-related client proteins, the inhibition of survival signals and the upregulation of apoptotic pathways. shRNA-mediated interference may have potential therapeutic utility in human breast cancer.
authors.affiliation: Department of General Surgery, Shanghai 10th People's Hospital, Tongji University School of Medicine, Shanghai 200072, China.
authors.forename: Keqiang
authors.initials: K
authors.lastname: Zuo
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.forename: Benjamin
authors.initials: B
authors.lastname: Pulli
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
authors.forename: Haidong
authors.initials: H
authors.lastname: Cai
authors.forename: Xueyu
authors.initials: X
authors.lastname: Yuan
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zhang
authors.forename: Zhongwei
authors.initials: Z
authors.lastname: Lv
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D001943:Breast Neoplasms / Q000628:therapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D006801:Humans; D051379:Mice; D034741:RNA, Small Interfering / Q000235:genetics*; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: D018841:HSP90 Heat-Shock Proteins; D034741:RNA, Small Interfering