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17-AAG inhibits vemurafenib-associated MAP kinase activation and is synergistic with cellular immunotherapy in a murine melanoma model.
PLoS One. 2018; 13(2):e0191264.Plos

Abstract

Heat shock protein 90 (HSP90) is a molecular chaperone which stabilizes client proteins with important roles in tumor growth. 17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of HSP90 ATPase activity, occupies the ATP binding site of HSP90 causing a conformational change which destabilizes client proteins and directs them towards proteosomal degradation. Malignant melanomas have active RAF-MEK-ERK signaling which can occur either through an activating mutation in BRAF (BRAFV600E) or through activation of signal transduction upstream of BRAF. Prior work showed that 17-AAG inhibits cell growth in BRAFV600E and BRAF wildtype (BRAFWT) melanomas, although there were conflicting reports about the dependence of BRAFV600E and BRAFWT upon HSP90 activity for stability. Here, we demonstrate that BRAFWT and CRAF are bound by HSP90 in BRAFWT, NRAS mutant melanoma cells. HSP90 inhibition by 17-AAG inhibits ERK signaling and cell growth by destabilizing CRAF but not BRAFWT in the majority of NRAS mutant melanoma cells. The highly-selective BRAFV600E inhibitor, PLX4032 (vemurafenib), inhibits ERK signaling and cell growth in mutant BRAF melanoma cells, but paradoxically enhances signaling in cells with wild-type BRAF. In our study, we examined whether 17-AAG could inhibit PLX4032-enhanced ERK signaling in BRAFWT melanoma cells. As expected, PLX4032 alone enhanced ERK signaling in the BRAFWT melanoma cell lines Mel-Juso, SK-Mel-2, and SK-Mel-30, and inhibited signaling and cell growth in BRAFV600E A375 cells. However, HSP90 inhibition by 17-AAG inhibited PLX4032-enhanced ERK signaling and inhibited cell growth by destabilizing CRAF. Surprisingly, 17-AAG also stimulated melanin production in SK-Mel-30 cells and enhanced TYRP1 and DCT expression without stimulating TYR production in all three BRAFWT cell lines studied as well as in B16F10 mouse melanoma cells. In vivo, the combination of 17-AAG and cellular immunotherapy directed against Tyrp1 enhanced the inhibition of tumor growth compared to either therapy alone. Our studies support a role for 17-AAG and HSP90 inhibition in enhancing cellular immunotherapy for melanoma.

Authors+Show Affiliations

Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.Dermatology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland, United States of America.Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.Dermatology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland, United States of America.Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America. Dermatology Branch, Center for Cancer Research, NCI, NIH, Bethesda, Maryland, United States of America. Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America. Department of Dermatology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America. Research and Development Service, VA Maryland Health Care System, Baltimore, Maryland, United States of America.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

29481571

Citation

Joshi, Sandeep S., et al. "17-AAG Inhibits Vemurafenib-associated MAP Kinase Activation and Is Synergistic With Cellular Immunotherapy in a Murine Melanoma Model." PloS One, vol. 13, no. 2, 2018, pp. e0191264.
Joshi SS, Jiang S, Unni E, et al. 17-AAG inhibits vemurafenib-associated MAP kinase activation and is synergistic with cellular immunotherapy in a murine melanoma model. PLoS ONE. 2018;13(2):e0191264.
Joshi, S. S., Jiang, S., Unni, E., Goding, S. R., Fan, T., Antony, P. A., & Hornyak, T. J. (2018). 17-AAG inhibits vemurafenib-associated MAP kinase activation and is synergistic with cellular immunotherapy in a murine melanoma model. PloS One, 13(2), e0191264. https://doi.org/10.1371/journal.pone.0191264
Joshi SS, et al. 17-AAG Inhibits Vemurafenib-associated MAP Kinase Activation and Is Synergistic With Cellular Immunotherapy in a Murine Melanoma Model. PLoS ONE. 2018;13(2):e0191264. PubMed PMID: 29481571.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - 17-AAG inhibits vemurafenib-associated MAP kinase activation and is synergistic with cellular immunotherapy in a murine melanoma model. AU - Joshi,Sandeep S, AU - Jiang,Shunlin, AU - Unni,Emmanual, AU - Goding,Stephen R, AU - Fan,Tao, AU - Antony,Paul A, AU - Hornyak,Thomas J, Y1 - 2018/02/26/ PY - 2017/12/17/received PY - 2018/01/01/accepted PY - 2018/2/27/entrez PY - 2018/2/27/pubmed PY - 2018/3/13/medline SP - e0191264 EP - e0191264 JF - PloS one JO - PLoS ONE VL - 13 IS - 2 N2 - Heat shock protein 90 (HSP90) is a molecular chaperone which stabilizes client proteins with important roles in tumor growth. 17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of HSP90 ATPase activity, occupies the ATP binding site of HSP90 causing a conformational change which destabilizes client proteins and directs them towards proteosomal degradation. Malignant melanomas have active RAF-MEK-ERK signaling which can occur either through an activating mutation in BRAF (BRAFV600E) or through activation of signal transduction upstream of BRAF. Prior work showed that 17-AAG inhibits cell growth in BRAFV600E and BRAF wildtype (BRAFWT) melanomas, although there were conflicting reports about the dependence of BRAFV600E and BRAFWT upon HSP90 activity for stability. Here, we demonstrate that BRAFWT and CRAF are bound by HSP90 in BRAFWT, NRAS mutant melanoma cells. HSP90 inhibition by 17-AAG inhibits ERK signaling and cell growth by destabilizing CRAF but not BRAFWT in the majority of NRAS mutant melanoma cells. The highly-selective BRAFV600E inhibitor, PLX4032 (vemurafenib), inhibits ERK signaling and cell growth in mutant BRAF melanoma cells, but paradoxically enhances signaling in cells with wild-type BRAF. In our study, we examined whether 17-AAG could inhibit PLX4032-enhanced ERK signaling in BRAFWT melanoma cells. As expected, PLX4032 alone enhanced ERK signaling in the BRAFWT melanoma cell lines Mel-Juso, SK-Mel-2, and SK-Mel-30, and inhibited signaling and cell growth in BRAFV600E A375 cells. However, HSP90 inhibition by 17-AAG inhibited PLX4032-enhanced ERK signaling and inhibited cell growth by destabilizing CRAF. Surprisingly, 17-AAG also stimulated melanin production in SK-Mel-30 cells and enhanced TYRP1 and DCT expression without stimulating TYR production in all three BRAFWT cell lines studied as well as in B16F10 mouse melanoma cells. In vivo, the combination of 17-AAG and cellular immunotherapy directed against Tyrp1 enhanced the inhibition of tumor growth compared to either therapy alone. Our studies support a role for 17-AAG and HSP90 inhibition in enhancing cellular immunotherapy for melanoma. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/29481571/17_AAG_inhibits_vemurafenib_associated_MAP_kinase_activation_and_is_synergistic_with_cellular_immunotherapy_in_a_murine_melanoma_model_ L2 - http://dx.plos.org/10.1371/journal.pone.0191264 DB - PRIME DP - Unbound Medicine ER -