Abstract
Cyclosporin A (CsA) is a widely used immunosuppressant drug. Its immunosuppressive activity occurs through the inhibition of the protein phosphatase calcineurin via formation of a ternary complex with cyclophilin A (CypA). CsA also inhibits endothelial cell proliferation and angiogenesis. This has been thought to occur through calcineurin inhibition as well. However, CsA is also a potent inhibitor of cyclophilins, a class of prolyl isomerases. Because calcineurin inhibition requires binding, and therefore inhibition of CypA, the relative contributions of calcineurin and cyclophilin inhibition in antiangiogenesis have not been addressed. We have taken a chemical biology approach to explore this question by dissociating the two activities of CsA at the molecular level. We have identified a nonimmunosuppressive analog of CsA that does not inhibit calcineurin but maintains inhibition of endothelial cell proliferation and in vivo angiogenesis. The same analog also maintains inhibition of all cyclophilin isoforms tested. We also show that a second, structurally distinct, cyclophilin inhibitor is sufficient to block endothelial cell proliferation. These results suggest that the inhibition of cyclophilins may play a larger role in the antiangiogenic activity of CsA than previously believed, and that cyclophilins may be potential antiangiogenic drug targets.
Footnotes
This work was supported in part by the National Institutes of Health National Cancer Institute [Grant R01-CA122814]; the National Institutes of Health National Center for Research Resources [Grant UL1-RR025005]; the Flight Attendant Medical Research Institute Fund; the Keck Foundation; the Walsh Prostate Cancer Fund; the Commonwealth Foundation; the National Institutes of Health Roadmap for Medical Research (to J.O.L.); the National Institutes of Health Medical Scientist Training Program [Grant T32GM07309] (to B.A.N.); Deutsche Forschungsgemeinschaft [Grants SFB 610, GRK 1026] (to G.F.); the National Eye Institute; a VA Merit Award; and the Burroughs Wellcome Fund (K.Z.).
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.111.180851.
↵
The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.-
ABBREVIATIONS:
- CsA
- cyclosporin A
- HUVEC
- human umbilical vein endothelial cells
- HFF
- human foreskin fibroblasts
- N-MeVal-4-CsA
- N-methylvaline-4-cyclosporin A
- Io
- ionomycin
- NFAT
- nuclear factor of activated T cells
- CyP
- cyclophilin
- VEGF
- vascular endothelial growth factor
- bFGF
- basic fibroblast growth factor
- CNV
- choroidal neovascularization
- DMSO
- dimethyl sulfoxide
- PBS
- phosphate-buffered saline
- BSA
- bovine serum albumin
- PAGE
- polyacrylamide gel electrophoresis
- DAPI
- 4,6-diamidino-2-phenylindole
- IL
- interleukin
- TBS-T
- 10 mM Tris, pH 8.0, 150 mM NaCl, 0.05% Tween 20
- DMEM
- Dulbecco's modified Eagle's medium
- RT
- room temperature
- ROI
- region of interest
- MAS
- Masson.
- Received February 21, 2011.
- Accepted May 5, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
