IOVS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Originally published In Press as doi:10.1167/iovs.07-1305 on February 15, 2008
 (Investigative Ophthalmology and Visual Science. 2008;49:2348-2356.)
© 2008 by The Association for Research in Vision and Ophthalmology, Inc.
DOI:  10.1167/iovs.07-1305
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
iovs.07-1305v1
49/6/2348    most recent
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Google Scholar
Right arrow Articles by Babchia, N.
Right arrow Articles by Mascarelli, F.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Babchia, N.
Right arrow Articles by Mascarelli, F.

17-AAG and 17-DMAG–Induced Inhibition of Cell Proliferation through B-Raf Downregulation in WTB-Raf–Expressing Uveal Melanoma Cell Lines

Narjes Babchia,1,2,3 Armelle Calipel,1,2,3,4 Frédéric Mouriaux,1,2,3,4 Anne-Marie Faussat,1 and Frédéric Mascarelli1,2,3

1From the Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris, France; 2Université Paris Descartes, Paris, France; 3INSERM, Paris, France; and 4Service Universitaire d’Ophtalmologie, CHRU, Caen, France.

PURPOSE. The HSP90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) has been shown to have promising results in antitumor activity through the degradation of the activated V600E mutant of B-Raf (V600EB-Raf) in cutaneous melanoma cell lines. It has different effects, however, on the wild-type form of B-Raf (WTB-Raf), according to the WTB-Raf activation levels in the tumor cells. Uveal melanoma cells express WTB-Raf and only rarely express V600EB-Raf. This study was conducted to investigate the effects of HSP90 inhibition on uveal melanoma cell lines.

METHODS. Human uveal melanoma cell lines were treated with the HSP90 inhibitors 17-AAG and 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17-DMAG). Cell proliferation was assessed by MTT staining, and apoptosis was quantified by flow cytometry. Analysis of the expression of HSP90 and activation of the MEK/ERK downstream signaling of B-Raf was performed by Western blot. Effects of the downregulation of the HSP90 cochaperone, cdc37, on cell proliferation and activation of MEK/ERK was investigated by siRNA strategy.

RESULTS. The inhibition of HSP90 downregulated B-Raf, decreased cell proliferation, and reduced activation of MEK/ERK in uveal melanoma cell lines expressing WTB-Raf. HSP90 inhibition also reduced the expression of Akt, but the inhibition of Akt had no effect on cell proliferation, ruling out a role of Akt in the 17-AAG–induced inhibition of cell proliferation. The downregulation of cdc37 did not affect MEK/ERK signaling and cell proliferation, demonstrating that the cochaperone was not required for HSP90-controlled stability of B-Raf. c-Kit was also downregulated after HSP90 inhibition. The combination of 17-DMAG with imatinib mesylate, the inhibitor of c-kit, had synergistic inhibitory effects on cell proliferation in WTB-Raf uveal melanoma cell lines.

CONCLUSIONS. These results suggest that targeting HSP90 in tandem with c-Kit inhibition may be a promising therapeutic approach to uveal melanoma.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by the Association for Research in Vision and Ophthalmology