Abstract
Exposure of the human malignant peripheral nerve sheath tumor cell lines STS-26T, ST88-14, and NF90-8 to nanomolar concentrations of both lovastatin and farnesyl transferase inhibitor (FTI)-1 but not to either drug alone induced cell death. ST88-14 and NF90-8 cells underwent apoptosis, yet dying STS-26T cells did not. FTI-1 cotreatment induced a strong and sustained autophagic response as indicated by analyses of microtubule-associated protein-1 light chain 3 (LC3)-II accumulation in STS-26T cultures. Extensive colocalization of LC3-positive punctate spots was observed with both lysosome-associated membrane protein (LAMP)-1 and LAMP-2 (markers of late endosomes/lysosomes) in solvent or FTI-1 or lovastatin-treated STS-26T cultures but very little colocalization in lovastatin/FTI-1-cotreated cultures. The absence of colocalization in the cotreatment protocol correlated with loss of LAMP-2 expression. Autophagic flux studies indicated that lovastatin/FTI-1 cotreatment inhibited the completion of the autophagic program. In contrast, rapamycin induced an autophagic response that was associated with cytostasis but maintenance of viability. These studies indicate that cotreatment of STS-26T cells with lovastatin and FTI-1 induces an abortive autophagic program and nonapoptotic cell death.
Footnotes
This work was supported by the National Institutes of Health National Institute of Environmental Health Sciences [Grant T32-ES012163] (to J.W.W. and M.K.); the National Institutes of Health National Cancer Institute [Grant R01-CA131990]; and the Department of the Army [Grants DAMD17-03-1-0182, W81XWH-05-1-0193]. The Microscopy and Imaging Resources Laboratory was supported by the National Institutes of Health [Center Grants P30ES06639, P30CA22453, and Roadmap Grant U54RR020843].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.174573.
↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
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ABBREVIATIONS:
- FPP
- farnesyl pyrophosphate
- FTI
- farnesyl transferase inhibitor
- R115777
- 6-amino[(4-chlorophenyl)(1-methyl-1H-imidazol-5-yl)methyl]-4-(3-chlorophenyl)-1-methylquinolin-2(1H)-one, tipifarnib
- SCH66336
- 4-(2-(4-(8-chloro-3,10-dibromo-6,11-dihydro-5H-benzo(5,6)cyclohepta(1,2-b)pyridin-11-yl)-1-piperidinyl)-2-oxoethyl)-1-piperidinecarboxamide, lonafarnib
- MPNST
- malignant peripheral nerve sheath tumor
- GGTI-2Z
- (5-nitrofuran-2-yl)methyl-(2Z,6E,10E)-3,7,11,15-tetramethylhexadeca-2,6,10,14-tetraenyl 4-chlorobutyl(methyl)phosphoramidate
- iSC
- immortalized Schwann cells
- GFP
- green fluorescent protein
- E64
- trans-epoxysuccinyl-l-leucylamido-(4-guanidino)butane
- LC3
- microtubule-associated protein light chain-3
- LAMP
- lysosome-associated membrane protein
- FACS
- fluorescence-activated cell sorting
- DEVDase
- proteolytic activity toward the sequence Asp-Glu-Val-Asp
- PBS
- phosphate-buffered saline
- BSA
- bovine serum albumin
- DAPI
- 4′,6-diamidino-2-phenylindole
- mTOR
- mammalian target of rapamycin.
- Received August 31, 2010.
- Accepted January 11, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
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