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Activated B-RAF Is an Hsp90 Client Protein That Is Targeted by the Anticancer Drug 17-Allylamino-17-Demethoxygeldanamycin

¹ The Institute of Cancer Research, Signal Transduction Team, Cancer Research UK Centre for Cell and Molecular Biology, London, United Kingdom; ² Gene and Oncogene Targeting Team and ³ Signal Transduction and Molecular Pharmacology Team, Cancer Research UK Centre for Cancer Therapeutics, The Institute of Cancer Research, Sutton, United Kingdom

Requests for reprints: Richard Marais, Signal Transduction Team, Cancer Research UK Centre for Cell and Molecular Biology, The Institute of Cancer Research, 237 Fulham Road, London, United Kingdom. Phone: 44-20-7153-5171; Fax: 44-20-7153-5171; E-mail: richard.marais{at}icr.ac.uk.

	Abstract

Top Abstract Introduction Materials and Methods Results and Discussion References

 
Hsp90 is a ubiquitously expressed molecular chaperone that folds, stabilizes, and functionally regulates many cellular proteins. The benzoquinone ansamysin 17-allylamino-17-demethoxygeldanamycin (17-AAG) is an anticancer drug that disrupts Hsp90 binding to its clients, causing their degradation through the ubiquitin-dependent proteasomal pathway. The protein kinase B-RAF is mutated in 7% of human cancers. The most common mutation (90%) is ^V600EB-RAF, which has constitutively elevated kinase activity, stimulates cancer cell proliferation, and promotes survival. Here, we show that ^V600EB-RAF is an Hsp90 client protein that requires Hsp90 for its folding and stability. ^V600EBRAF is more sensitive to degradation by 17-AAG treatment than ^WTB-RAF and we show that the majority of the other mutant forms of B-RAF are also sensitive to 17-AAG–mediated proteasomal degradation. Our data show that B-RAF is an important target for 17-AAG in human cancer.

	Introduction

Top Abstract Introduction Materials and Methods Results and Discussion References

 
The molecular chaperone Hsp90 is part of a multiprotein complex with cochaperones, such as cdc37, p60Hop, and Hsp70 (1). This complex folds, stabilizes, and functionally regulates many client proteins, including many protein kinases that are implicated in cancer (2, 3). Because Hsp90 inhibition induces degradation of its client proteins, it has attracted considerable interest as a therapeutic target for anticancer drugs (2, 3). The most advanced of these is the benzoquinone ansamycin 17-allylamino-17-demethoxygeldanamycin (17-AAG), an agent that has shown promising activity in human tumor xenograft models (4, 5) and is now undergoing phase II clinical trials (6, 7). The combinatorial degradation of several oncogenic proteins seems to be a therapeutic advantage of Hsp90 inhibition (8) but it also masks the identification of specific target clients that could play a key role in particular diseases.

The protein kinase C-RAF is an important Hsp90 client protein (9). C-RAF is a component of the RAS/RAF/MEK [mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase]/ERK signaling module, a pathway that regulates cell fate, and the activity of which is elevated in 30% of human cancers (10). The C-RAF-related protein B-RAF is mutated in 70% of human melanomas and a range of other cancers (11, 12). The most common B-RAF mutant is a glutamic acid for valine substitution at position 600 (^V600EB-RAF; previously incorrectly assigned as ^V599EB-RAF; ref. 11), resulting in a kinase with elevated activity that stimulates constitutive signaling, proliferation, and survival, establishing that B-RAF is a human oncogene and novel therapeutic target (10). Over 50 other B-RAF mutations have been described, the majority of which cluster to two regions of the kinase domain, the glycine-rich loop and activation segment (12). Mostly, these also have elevated kinase activity (high or intermediate levels) but a small number have reduced kinase activity or lack kinase activity altogether. The reduced activity mutants still signal to ERK because they activate C-RAF, which then directly activates MEK signaling (13).

Here, we show that 17-AAG stimulates B-RAF degradation in cancer cells and that mutant forms of B-RAF are more sensitive to 17-AAG than the wild-type protein. B-RAF binds to Hsp90 and targeting B-RAF with 17-AAG inhibits signaling in cancer cells. Thus, B-RAF is an Hsp90 client protein and an exciting downstream target of the Hsp90 inhibitor 17-AAG.

	Materials and Methods

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Expression vectors and cell culture techniques. Cells are routinely cultured in DMEM/10% fetal bovine serum (FBS; A375, CHL, SW620, 501MEL, COLO829, WM266.4, and SK-MEL-2) or RPMI 1640/10% FBS (H508), or 50:50 DMEM/RPMI 1640 10% FBS with 10 mmol/L HEPES and ITS supplement (Sigma, Poole, United Kingdom) at 37°C in 10% CO₂. COS cells were cultured, transfected, and protein extracts were prepared as described (14); cellular sensitivity to 17AAG was measured by sulforhodamine B dye. The percentage control A₅₄₀ is plotted against the logarithm of the drug concentration and analyzed by nonlinear regression to a four-variable logistic equation (Graphpad Prism, Graphpad Software, Inc., San Diego, CA). Expression vectors for B-RAF and the mutants have been described (13). RAF kinase activity was measured in a kinase cascade assay with glutathione S-transferase (GST)–MEK, GST-ERK, and myelin basic proteins as sequential substrates (13). For coimmunoprecipitation assays, cells were extracted as described (13) and standard approaches were used. The following antibodies were used: mouse monoclonal anti-B-RAF (Santa Cruz Biotechnologies, Calne, United Kingdom), rabbit polyclonal anti-B-RAF (R. Marais), mouse anti-RAF-1 (Signal Transduction Laboratories, Cowley, United Kingdom), mouse monoclonal anti-myc (clone 9E10; The Institute of Cancer Research Hybridoma Unit, London, United Kingdom), rabbit polyclonal anti-p42 ERK2 (C. Marshall, The Institute of Cancer Research), mouse monoclonal anti-ppERK1/2 (Sigma), rabbit polyclonal anti-ppMEK1/2 (New England Biolabs, Hitchin, United Kingdom), and mouse anti-cdc37 (Affinity Biolabs, Exeter, United Kingdom), mouse anti-Hsp70, and anti-Hsp90 (Stressgen, York, United Kingdom). 17-AAG was obtained from Dr. Ed Sauseville (National Cancer Institute, Bethesda, MD).

	Results and Discussion

Top Abstract Introduction Materials and Methods Results and Discussion References

 
Oncogenic B-RAF is hypersensitive to 17-allylamino-17-demethoxygeldanamycin. To determine whether B-RAF is an Hsp90 client protein, we tested its sensitivity to 17-AAG using C-RAF as a control because C-RAF is closely related to B-RAF and is a known Hsp90 client protein. 17-AAG caused a reduction in endogenous C-RAF protein levels in COS cells in a concentration-dependent manner (Fig. 1A). This was a specific effect because there was no reduction in ERK2 protein levels in the same samples. However, as expected, the reduction in C-RAF was accompanied by decreased ERK phosphorylation (Fig. 1A). In contrast to C-RAF, transiently expressed myc-epitope-tagged ^WTB-RAF was relatively stable, with only a small reduction in protein levels even at 1,000 nmol/L 17-AAG (Fig. 1A). Importantly, myc-tagged ^V600EB-RAF was significantly more sensitive to 17-AAG than ^WTB-RAF in these cells, its sensitivity paralleling that of C-RAF (Fig. 1B).

View larger version (44K): [in this window] [in a new window] [Download PPT slide]   Figure 1. Down-modulation of B-RAF by 17-AAG. Western blot analysis of myc-tagged B-RAF, endogenous C-RAF, endogenous ERK, and activated ERK (ppERK) in COS cells transfected with WTB-RAF (A) or V600EB-RAF (B) and treated with different concentration of 17-AAG (1,000, 500, 100, and 50 nmol/L) for 24 hours. C, Western blot for endogenous B-RAF, C-RAF, ERK2, and activated ERK in CHL or A375 cells treated with 1,000 nmol/L 17-AAG for the indicated times. D, COS cells were transfected with WTB-RAF, with or without G12VRAS as indicated, treated with 17-AAG (1 µmol/L) for 24 hours, and blotted for exogenous B-RAF and G12VRAS or endogenous C-RAF. The graph to the right provides quantification of the blotting data.

B-RAF is an Hsp90 client protein. Our data suggest that B-RAF is an Hsp90 client protein and that oncogenic B-RAF is more dependent on this chaperone for its folding, stability, and/or function than the wild-type protein. We tested whether endogenous B-RAF and Hsp90 associate with each other in intact CHL and A375 cells. We were unable to detect Hsp90 in B-RAF immunoprecipitates from CHL cells but did observe Hsp90 in B-RAF immunoprecipitates from A375 cells (Fig. 2A). Treatment of cells with 17-AAG reduced Hsp90 binding to B-RAF in A375 cells (Fig. 2B). The kinase-specific Hsp90 cochaperone p50^cdc37 was found to also coprecipitate with ^V600EB-RAF in A375 cells but this interaction was disrupted following treatment with 17-AAG (Fig. 2A and B). Surprisingly, we did not observe any binding of C-RAF to Hsp90 in either cell line either in the absence or presence of 17-AAG (Fig. 2A and B). Thus, it is difficult to conclude that ^WTB-RAF is not an Hsp90 client protein. One possibility is that ^WTB-RAF forms a very transient complex with Hsp90, making it difficult to detect under these conditions. Alternatively, B-RAF may only form a complex with Hsp90 when activated or mutated and it is only then that it becomes sensitized to 17-AAG. In contrast to Hsp90, Hsp70 did not bind to B-RAF in untreated CHL or A375 cells, but was recruited to ^WTB-RAF and ^V600EB-RAF following 17-AAG treatment (Fig. 2A and B).

View larger version (32K): [in this window] [in a new window] [Download PPT slide]   Figure 2. B-RAF is an Hsp90 client protein. A and B, endogenous B-RAF and C-RAF were immunoprecipitated (IP) from CHL and A375 cells that were untreated (A) or treated with 17-AAG (1 µmol/L, 4 hours; B) and the complexes were immunoblotted for B-RAF, C-RAF, Hsp90, Hsp70, and cdc37, which is right below the heavy chain (HC) of the antibody. C, WM266.4 cells were untreated or treated with 17-AAG as indicated (24 hours) in the absence or presence of ALLN (100 µmol/L). Whole cell lysates (WCL) or the separated detergent soluble and insoluble fractions were Western blotted for B-RAF or C-RAF.

Most, but not all, B-RAF mutants are hypersensitive to 17-allylamino-17-demethoxygeldanamycin. Next, we tested a selection of other B-RAF mutants present in human cancers. Transiently expressed myc-epitope-tagged versions of ^V600DB-RAF and ^G469AB-RAF, two high-activity mutants (700- and 230-fold activated, respectively; ref. 13) are as sensitive to 17-AAG as ^V600EB-RAF in COS cells (Fig. 3A). Similarly, the intermediate activity mutant ^G469EB-RAF, the impaired-activity mutants ^G596RB-RAF and ^G466VB-RAF, and the kinase-inactive mutant ^G594VB-RAF were hypersensitive to 17-AAG (Fig. 3A). However, the high-activity mutant ^E586KB-RAF (130-fold activated) and the intermediate activity mutant ^L597VB-RAF (65-fold activated) were not hypersensitive to 17-AAG, displaying similar rates of protein depletion as were observed with ^WTB-RAF (Fig. 3A).

View larger version (85K): [in this window] [in a new window] [Download PPT slide]   Figure 3. Susceptibility of mutant forms of B-RAF to 17-AAG. A, COS cells were transiently transfected with vector control or the indicated myc-tagged B-RAF mutant proteins and treated with 17-AAG (1 µmol/L) for the indicated times and blotted for myc-tagged B-RAF, endogenous C-RAF, and total ERK2 (as a loading control). B, WM266.4, Colo829, A375, Mel501, SK-Mel2, CHL, SW620, H1666, and H508 cells were treated with various concentrations of 17-AAG as in Fig. 1A and Western blotted for endogenous B-RAF, C-RAF, ERK2, and activated ERK. C, B-RAF kinase activity from CHL, SW620, SKMEL-2, WM266.4, A375, and Colo829 cells following 17-AAG treatment at the indicated concentrations for 24 hours. D, COS cells expressing myc-tagged G464VB-RAF were treated with 17-AAG as in Fig. 1A and blotted for myc-tagged B-RAF and endogenous ERK2. E, BE cells or BE cells expressing NQO1/DT-diaphorase (BE-2) were treated with various concentrations of 17-AAG as in Fig. 1A and Western blotted for endogenous B-RAF, C-RAF, ppERK, and ERK2 (loading control).

Note that the level of kinase activity correlates with the levels of B-RAF expression (Fig. 3B and C) and is directly affected by 17-AAG treatment. Furthermore, there is a close correlation between B-RAF kinase activity and the reduction in ERK phosphorylation in Colo829, A375, and WM266.4 cells, confirming that oncogenic B-RAF drives ERK signaling in cells.

Next, we tested the sensitivity of different cell lines to Hsp90 inhibition by measuring their proliferation in the presence of 17-AAG. All of the cancer lines that we tested were relatively sensitive to 17-AAG (see ref. 5 for data on a large panel of cell lines) and we observe that the cells that harbor mutant B-RAF are no more sensitive to 17-AAG than cells in which B-RAF is wild type (Table 1). Thus, there is no correlation between B-RAF mutation status and the sensitivity of the cells to 17-AAG. This result may seem counterintuitive at first sight but it is consistent with our observations. We have shown that C-RAF, ^V600EB-RAF, and, importantly, activated ^WTB-RAF are relatively sensitive to 17-AAG (Fig. 1A and D). Clearly, in melanoma cells harboring mutations in B-RAF, ERK signaling depends on the mutant protein so cells would be sensitive to 17-AAG. Similarly, in the lines where B-RAF is not mutated, ERK will be activated downstream of either C-RAF or activated ^WTB-RAF and both of these are sensitive to 17-AAG. These studies show that 17-AAG is a versatile drug that will inhibit ERK signaling in the majority of cell lines because it targets C-RAF, active B-RAF, and most of the mutant forms of B-RAF.

We have shown that ^V600EB-RAF, the most clinically relevant mutant, is hypersensitive to 17-AAG and that six of the other eight mutants we tested are also hypersensitive to this drug. Thus, mutant B-RAF from the majority of human cancer patients will be sensitive to 17-AAG. Intriguingly, there does not seem to be a correlation to the position of the mutation and sensitivity to 17-AAG. Mutants involving glycine-rich loop residues (G466V, G469A, and G469E); the activation segment residues (D594V, G596R, V600E, and V600D); and mutants with high (G469A, V600E, and V600D), intermediate (G466V), and reduced (G469E and G596R) kinase activity are all hypersensitive. Structural studies have revealed that B-RAF is held in an inactive conformation by an unusual interaction between the glycine-rich loop and the activation segment (13). The mutations that occur in these regions in cancer are thought to disrupt this interaction, destabilizing the inactive conformation and allowing the active conformation to predominate (13).

Our studies suggest that it is the adoption of the active conformation rather than the level of activity that determines 17-AAG sensitivity. We note that the kinase-inactive mutant ^D594VB-RAF is hypersensitive to 17-AAG, demonstrating that kinase activity is not required for sensitivity. However, at least two of the mutants, ^L597VB-RAF and ^E586KB-RAF, were not hypersensitive despite the fact that one (L597V) is in the activation segment and has intermediate activity and the other (E586K) is an activation loop mutant with high activity. It is unclear why these mutants lack sensitivity. They may adopt a unique active conformation that is insensitive to 17-AAG or they may fold into the active form in a manner that is independent of Hsp90. Importantly, these mutations could provide a mechanism whereby B-RAF could become resistant to 17-AAG in the clinic and they are being further investigated.

Another route to 17-AAG resistance for B-RAF could be intrinsic to the cancer cells. We find that ^G464VB-RAF is sensitive to 17-AAG when exogenously expressed in COS cells (Fig. 3D), whereas endogenous ^G464VB-RAF is not sensitive to 17-AAG in BE cells (Fig. 3E). However, BE cells have a destabilizing point mutations in DT-diaphorase/DT-diaphorase and so lack this enzyme activity (17). Consequently, their ability to convert 17-AAG to the active metabolite is reduced and consequently their client proteins are relatively resistant to 17-AAG-mediated degradation (5). However, when BE cells are engineered to express functioning NQO1/DT-diaphorase (BE-2 cells; ref. 17), ^G464VB-RAF becomes more sensitive to 17-AAG. These data confirm that ^G464VB-RAF is an Hsp90 client protein and suggest that the loss of NQO1/DT-diaphorase could result in the development of clinical resistance.

In summary, this study shows that B-RAF is an Hsp90 client protein. Our data show that active B-RAF and most of the mutant forms of B-RAF from human cancer are more sensitive to the anticancer drug 17-AAG than inactive ^WTB-RAF. The sensitivity of the mutants seems to be determined by their conformation rather than activation status and these findings clearly have therapeutic implications in melanoma and other cancers in which this pathway plays a role. In particular, our results suggest that melanoma cells will be sensitive to 17-AAG whether they rely on B-RAF or C-RAF for signaling to ERK. Of note are the findings that melanoma cells display greater than average sensitivity to 17-AAG than most other cells in the National Cancer Institute 60 human tumor cell panel and human melanoma xenografts respond to 17-AAG (18). Finally, prolonged stable disease has been reported in two patients with advanced metastatic malignant melanoma in a phase I clinical trial of weekly administered 17-AAG (19), demonstrating the potential of this anticancer agent.

	Acknowledgments

 
Grant support: Cancer Research UK grants C107/A3096 and C309/A2187 and The Institute of Cancer Research.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

	Footnotes

 
Note: Y. Light is currently in Inpharmatica Ltd., London, United Kingdom. P. Workman is a Cancer Research UK Life Fellow.

Received 7/26/05. Revised 10/ 4/05. Accepted 10/12/05.

	References

Top Abstract Introduction Materials and Methods Results and Discussion References

 

1. Prodromou C, Pearl LH. Structure and functional relationships of Hsp90. Curr Cancer Drug Targets 2003;3:301–23.[CrossRef][Medline]
2. Neckers L, Neckers K. Heat-shock protein 90 inhibitors as novel cancer chemotherapeutics—an update. Expert Opin Emerg Drugs 2005;10:137–49.[CrossRef][Medline]
3. Maloney A, Workman P. HSP90 as a new therapeutic target for cancer therapy: the story unfolds. Expert Opin Biol Ther 2002;2:3–24.[CrossRef][Medline]
4. Solit DB, Zheng FF, Drobnjak M, et al. 17-Allylamino-17-demethoxygeldanamycin induces the degradation of androgen receptor and HER-2/neu and inhibits the growth of prostate cancer xenografts. Clin Cancer Res 2002;8:986–93.[Abstract/Free Full Text]
5. Kelland LR, Sharp SY, Rogers PM, et al. DT-Diaphorase expression and tumor cell sensitivity to 17-allylamino, 17-demethoxygeldanamycin, an inhibitor of heat shock protein 90. J Natl Cancer Inst 1999;91:1940–9.[Abstract/Free Full Text]
6. Sausville EA, Tomaszewski JE, Ivy P. Clinical development of 17-allylamino, 17-demethoxygeldanamycin. Curr Cancer Drug Targets 2003;3:377–83.[CrossRef][Medline]
7. Banerji U, Judson I, Workman P. The clinical applications of heat shock protein inhibitors in cancer—present and future. Curr Cancer Drug Targets 2003;3:385–90.[CrossRef][Medline]
8. Workman P. Combinatorial attack on multistep oncogenesis by inhibiting the Hsp90 molecular chaperone. Cancer Lett 2004;206:149–57.[CrossRef][Medline]
9. Isaacs JS, Xu W, Neckers L. Heat shock protein 90 as a molecular target for cancer therapeutics. Cancer Cell 2003;3:213–7.[CrossRef][Medline]
10. Wellbrock C, Karasarides M, Marais R. The RAF proteins take centre stage. Nat Rev Mol Cell Biol 2004;5:875–85.[CrossRef][Medline]
11. Davies H, Bignell GR, Cox C, et al. Mutations of the BRAF gene in human cancer. Nature 2002;417:949–54.[CrossRef][Medline]
12. Garnett MJ, Marais R. Guilty as charged; B-RAF is a human oncogene. Cancer Cell 2004;6:313–9.[CrossRef][Medline]
13. Wan PT, Garnett MJ, Roe SM, et al. Mechanism of activation of the RAF-ERK signaling pathway by oncogenic mutations of B-RAF. Cell 2004;116:855–67.[CrossRef][Medline]
14. Wellbrock C, Ogilvie L, Hedley D, et al. V599EB-RAF is an oncogene in melanocytes. Cancer Res 2004;64:2338–42.[Abstract/Free Full Text]
15. Karasarides M, Chiloeches A, Hayward R, et al. B-RAF is a therapeutic target in melanoma. Oncogene 2004;23:6292–8.[CrossRef][Medline]
16. Maldonado JL, Fridlyand J, Patel H, et al. Determinants of BRAF mutations in primary melanomas. J Natl Cancer Inst 2003;95:1878–90.[Abstract/Free Full Text]
17. Sharp SY, Kelland LR, Valenti MR, et al. Establishment of an isogenic human colon tumor model for NQO1 gene expression: application to investigate the role of DT-diaphorase in bioreductive drug activation in vitro and in vivo. Mol Pharmacol 2000;58:1146–55.[Abstract/Free Full Text]
18. Burger AM, Fiebig HH, Stinson SF, Sausville EA. 17-(Allylamino)-17-demethoxygeldanamycin activity in human melanoma models. Anticancer Drugs 2004;15:377–87.[CrossRef][Medline]
19. Banerji U, O'Donnell A, Scurr M, et al. Phase I pharmacokinetic and pharmacodynamic study of 17-allylamino, 17-demethoxygeldanamycin in patients with advanced malignancies. J Clin Oncol 2005;23:4152–61.[Abstract/Free Full Text]

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