Abstract
The present study was undertaken to compare the cellular transport characteristics of [3H]NPI-0052 (1R,4R,5S)-4-(2-chloroethyl)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-5-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione (marizomib; salinosporamide A) and [3H]NPI-0047 (1R,4R, 5S)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-4-ethyl-5-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione in RPMI 8226 multiple myeloma and PC-3 prostate adenocarcinoma cells to determine whether these properties explain differences in the cytotoxic potencies of these chemical analogs. The results indicate that marizomib, which possesses a chemical-leaving group, is more cytotoxic to both cell lines and inhibits proteasome activity more completely at lower concentrations than NPI-0047, a nonleaving-group analog. Moreover, it was found that both compounds accumulate in these cells by simple diffusion and the same carrier-mediated transport system. Although the rate of uptake is similar, the cellular efflux, which does not seem to be mediated by a major ATP-binding cassette (ABC)-efflux transporter, is more rapid for NPI-0047 than for marizomib. Experiments revealed that the irreversible binding of marizomib to the proteasome is responsible for its slower efflux, longer duration of action, and greater cytotoxicity compared with NPI-0047. The discovery that major ABC transporters of the multidrug resistance-associated protein family do not seem to be involved in the accumulation or removal of these agents suggests they may not be affected by multidrug resistance mechanisms during prolonged administration.
Footnotes
This work was supported by the National Institutes of Health National Institute of General Medical Sciences [Grant R01-GM077336]; the National Institutes of Health National Center for Research Resources [Grant P20-RR021940]; and Nereus Pharmaceuticals, Inc., San Diego, CA. A.O. was supported in part by the National Institutes of Health National Institute of Environmental Health Sciences [Grant T32-ES07079].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.177824.
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ABBREVIATIONS:
- CP
- core particle
- ABC
- ATP-binding cassette
- CT-L
- chymotrypsin-like
- FBS
- fetal bovine serum
- LG
- leaving group
- NLG
- nonleaving group
- MM
- multiple myeloma
- PBS
- phosphate-buffered saline
- DMSO
- dimethyl sulfoxide
- HPLC
- high-performance liquid chromatography
- MRP
- multidrug resistance protein
- NPI-0052
- (1R,4R,5S)-4-(2-chloroethyl)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-5-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione
- NPI-0047
- (1R,4R,5S)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-4-ethyl-5-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione
- MK-571
- 3-[[[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl][[3-(dimethylamino)-3-oxopropyl]thio]methyl]thio]propanoic acid
- NPI-2063
- (1R,4R,5S)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-4,5-dimethyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione
- NPI-2080
- (1R,4R,5S)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-5-methyl-4-propyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione
- NPI-2150
- 2-((1R,4R,5S)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-5-methyl-3,7-dioxo-6-oxa-2-azabicyclo[3.2.0]heptan-4-yl)ethyl methanesulfonate
- NPI-2151
- 2-((1R,4R,5S)-1-((S)-((S)-cyclohex-2-enyl)(hydroxy)methyl)-5-methyl-3,7-dioxo-6-oxa-2-azabicyclo[3.2.0]heptan-4-yl)ethyl benzenesulfonate
- NPI-2162
- (1S,4R,5S)-4-(2-chloroethyl)-1-((S)-cyclohex-2-enecarbonyl)-5-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione
- NPI-2146
- (1S,4R,5S)-1-((S)-cyclohex-2-enecarbonyl)-4-ethyl-5-methyl-6-oxa-2-azabicyclo[3.2.0]heptane-3,7-dione.
- Received December 6, 2010.
- Accepted February 7, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
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