Cancer Chemotherapy and Pharmacology

, Volume 56, Issue 2, pp 126–137 | Cite as

Comparison of 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17DMAG) and 17-allylamino-17-demethoxygeldanamycin (17AAG) in vitro: effects on Hsp90 and client proteins in melanoma models

  • Victoria Smith
  • Edward A. SausvilleEmail author
  • Richard F. Camalier
  • Heinz-Herbert Fiebig
  • Angelika M. Burger
Original Article


The heat shock protein Hsp90 is a potential target for drug discovery of novel anticancer agents. By affecting this protein, several cell signaling pathways may be simultaneously modulated. The geldanamycin analog 17AAG has been shown to inhibit Hsp90 and associated proteins. Its clinical use, however, is hampered by poor solubility and thus, difficulties in formulation. Therefore, a water-soluble derivative was desirable and 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17DMAG) is such a derivative. Studies were carried out in order to evaluate the activity and molecular mechanism(s) of 17DMAG in comparison with those of 17-allylamino-demethoxygeldanamycin (17AAG). 17DMAG was found to be more potent than 17AAG in a panel of 64 different patient-derived tumor explants studied in vitro in the clonogenic assay. The tumor types that responded best included mammary cancers (six of eight), head and neck cancers (two of two), sarcomas (four of four), pancreas carcinoma (two of three), colon tumors (four of eight for 17AAG and six of eight for 17DMAG), and melanoma (two of seven). Bioinformatic comparisons suggested that, while 17AAG and 17DMAG are likely to share the same mode(s) of action, there was very little similarity with standard anticancer agents. Using three permanent human melanoma cell lines with differing sensitivities to 17AAG and 17DMAG (MEXF 276L, MEXF 462NL and MEXF 514L), we found that Hsp90 protein was reduced following treatment at a concentration associated with total growth inhibition. The latter occurred in MEXF 276L cells only, which are most sensitive to both compounds. The depletion of Hsp90 was more pronounced in cells exposed to 17DMAG than in those treated with 17AAG. The reduction in Hsp90 was associated with the expression of erbB2 and erbB3 in MEXF 276L, while erbB2 and erbB3 were absent in the more resistant MEXF 462NL and MEXF 514L cells. Levels of known Hsp90 client proteins such as phosphorylated AKT followed by AKT, cyclin D1 preceding cdk4, and craf-1 declined as a result of drug treatment in all three melanoma cell lines. However, the duration of drug exposure needed to achieve these effects was variable. All cell lines showed increased expression of Hsp70 and activated cleavage of PARP. No change in PI3K expression was observed and all melanoma cells were found to harbor the activating V599E BRAF kinase mutation. The results of our in vitro studies are consistent with both 17AAG and 17DMAG acting via the same molecular mechanism, i.e. by modulating Hsp90 function. Since 17DMAG can be formulated in physiological aqueous solutions, the data reported here strongly support the development of 17DMAG as a more pharmaceutically practicable congener of 17AAG.


17DMAG 17AAG Hsp90 modulation Melanoma 









Phosphate-buffered saline


National Cancer Institute




Heat shock protein


Melanoma xenograft established by Fiebig et al.


Poly-adenosine ribose polymerase


Total growth inhibition (no change vs initial cell number)


Growth-inhibitory concentration 50% compared to control


Tumor clonogenic assay


Ethylenediaminetetraacetic acid



This work was supported by a contract from the US NCI (no. N01-CM-27026) to A.M.B. and H.H.F. We wish to thank Dr. Armin Maier and Anke Masch for their assistance with performing and evaluating the clonogenic assays and Dr. Aiguo Zhang for her help with the BRAF mutation analyses.


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Victoria Smith
    • 1
  • Edward A. Sausville
    • 2
    • 3
    Email author
  • Richard F. Camalier
    • 2
  • Heinz-Herbert Fiebig
    • 1
  • Angelika M. Burger
    • 1
    • 4
  1. 1.Tumor Biology Center at the University of FreiburgFreiburgGermany
  2. 2.Developmental Therapeutics ProgramDCTD, NCIBethesdaUSA
  3. 3.Associate Director for Clinical Research, University of Maryland Greenebaum Cancer CenterUniversity of Maryland MedicineBaltimoreUSA
  4. 4.Sunnybrook & Women’s College Health Sciences CentreTorontoCanada

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