Effects of Raf-1 siRNA on human cerebral microvascular endothelial cells: a potential therapeutic strategy for inhibition of tumor angiogenesis.
The serine/threonine kinase Raf-1 is involved in the regulation of tumor cell survival, proliferation and metastasis formation, and has therefore emerged as a promising target for cancer therapy. In addition, Raf-1 activity mediates proliferation of endothelial cells thereby promoting angiogenesis and invasive growth of various tumors, including highly vascularized malignant glioblastoma. The aim of this study was to evaluate the effects of small inhibitory RNA (siRNA) directed against Raf-1 on viability, proliferation and motility in glioma cells and cerebral endothelial cells. Half-quantitative RT-PCR and Western blotting revealed efficient siRNA-mediated Raf-1 down regulation in glioma cells (U373, U251) and in human cerebral microvascular endothelial cells (HCMEC). Surprisingly, Raf-1 gene silencing failed to affect cell survival, proliferation or migration activity in the glioblastoma cell lines. In HCMEC, however, pronounced decrease of cell survival and significant inhibition of tube formation was achieved by Raf-1 siRNA compared to non-functional siRNA or vehicle controls. In conclusion, Raf-1 silencing appears as a potential therapeutic strategy to inhibit brain tumor angiogenesis and thereby outgrowth of highly vascularized glioblastoma multiforme, whereas direct cytotoxic effects of Raf-1 knockdown in tumor cells may vary.
Culmsee
Carsten
C
Pharmaceutical Biology-Biotechnology, Department of Pharmacy, Ludwig-Maximilians University Munich, Germany. carsten.culmsee@cup.uni-muenchen.de
Gasser
Edith
E
Hansen
Sabine
S
Tonn
Joerg-Christian
JC
Wagner
Ernst
E
Goldbrunner
Roland
R
D000704:Analysis of Variance; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D042783:Endothelial Cells / Q000187:drug effects*; D005354:Fibrosarcoma / Q000378:metabolism / Q000473:pathology; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D009154:Mutation / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors
D012333:RNA, Messenger; D034741:RNA, Small Interfering; D019908:Proto-Oncogene Proteins c-raf