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The dysfunction of endothelial progenitor cells (EPCs) limits their potential for the treatment of ischemia and atherosclerosis. Therefore, we investigated the effect of tripterine on EPC function and examined the underlying mechanisms. The effect of tripterine, an active component of Tripterygium wilfordii Hook, on the enhancement of EPC function and the efficiency of EPC transplantation was investigated in vitro and in vivo. Treatment of EPCs with tripterine at 2.5 µM for 4 h inhibited oxidized low-density lipoprotein (ox-LDL) induced ROS production, cell apoptosis, and cell senescence and improved the migration and tube formation capacities of EPCs treated with ox-LDL (200 µg/ml). In vivo studies showed that tripterine conditioning of EPCs administered to ischemic foci improved blood perfusion and microvascular density in a mouse hindlimb ischemia model. Examination of the underlying mechanisms indicated that the effect of tripterine is mediated by the induction of heat shock protein 32 expression and the inhibition of JNK activation. The present results are of clinical significance because they suggest the potential of tripterine as a therapeutic agent to improve the efficacy of EPC transplantation for the treatment of ischemic diseases. J. Cell. Physiol. 230: 1139-1147, 2015. © 2014 Wiley Periodicals, Inc., A Wiley Company [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]