17-Aminogeldanamycin selectively diminishes IRE1α-XBP1s pathway activity and cooperatively induces apoptosis with MEK1/2 and BRAFV600E inhibitors in melanoma cells of different genetic subtypes

Apoptosis. 2019 Aug;24(7-8):596-611. doi: 10.1007/s10495-019-01542-y.

Abstract

Outcomes of melanoma patient treatment remain unsatisfactory despite accessibility of oncoprotein-targeting drugs and immunotherapy. Here, we reported that 17-aminogeldanamycin more potently activated caspase-3/7 in BRAFV600E melanoma cells than geldanamycin, another inhibitor of heat shock protein 90 (HSP90). 17-aminogeldanamycin alleviated self-triggered compensatory increase in HSP70 mRNA level and induced endoplasmic reticulum (ER) stress, which was followed by selective diminution of cytoprotective IRE1α-XBP1s pathway activity of unfolded protein response (UPR), inhibition of ERK1/2 activity and induction of apoptosis. Concomitantly, ATF6/p50 level and expression of PERK-dependent genes, CHOP and BIM, remained unaltered. This might result from an inframe deletion in EIF2AK3 leading to a PERKL21del variant revealed by whole-exome sequencing in melanoma cell lines. 17-aminogeldanamycin exhibited similar activity in NRASQ61R melanoma cells that harbored a heterozygous inactivating variant of NAD(P)H:quinone oxidoreductase 1 (NQO1P187S). In addition, 17-aminogeldanamycin acted cooperatively with trametinib (an inhibitor of MEK1/2) and vemurafenib (an inhibitor of BRAFV600E) in induction of apoptosis in melanoma cell lines as evidenced by in-cell caspase-3/7 activation and PARP cleavage that occurred earlier compared with either drug used alone. As trametinib and vemurafenib did not significantly affect HSP70 and GRP78 transcript levels, cooperation of MEK/BRAFV600E inhibitors and 17-aminogeldanamycin might result from a concurrent inhibition of the RAS/RAF/MEK/ERK cascade and IRE1α-dependent signaling, and cell-intrinsic ER homeostasis can determine the extent of the drug cooperation. Our study indicates that 17-aminogeldanamycin takes several advantages compared with other HSP90-targeting compounds, and can complement activity of BRAF/MEK inhibitors in melanoma cells of different genetic subtypes.

Keywords: 17-aminogeldanamycin; Endoplasmic reticulum stress; HSP90 inhibitors; IRE-1α; Melanoma; Targeted therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Benzoquinones / chemistry
  • Benzoquinones / pharmacology*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Endoplasmic Reticulum Chaperone BiP
  • Endoplasmic Reticulum Stress / drug effects
  • Endoribonucleases / metabolism*
  • GTP Phosphohydrolases / genetics
  • Heat-Shock Proteins / genetics
  • Humans
  • Lactams, Macrocyclic / chemistry
  • Lactams, Macrocyclic / pharmacology*
  • MAP Kinase Kinase 1 / antagonists & inhibitors
  • MAP Kinase Kinase 2 / antagonists & inhibitors
  • Melanoma / genetics*
  • Melanoma / metabolism
  • Melanoma / pathology
  • Membrane Proteins / genetics
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors
  • Proto-Oncogene Proteins B-raf / genetics
  • Signal Transduction / drug effects*
  • Unfolded Protein Response / drug effects
  • X-Box Binding Protein 1 / metabolism

Substances

  • Antineoplastic Agents
  • Benzoquinones
  • Endoplasmic Reticulum Chaperone BiP
  • HSPA5 protein, human
  • Heat-Shock Proteins
  • Lactams, Macrocyclic
  • Membrane Proteins
  • Protein Kinase Inhibitors
  • X-Box Binding Protein 1
  • XBP1 protein, human
  • MAP2K2 protein, human
  • BRAF protein, human
  • ERN1 protein, human
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins B-raf
  • MAP Kinase Kinase 1
  • MAP Kinase Kinase 2
  • MAP2K1 protein, human
  • Endoribonucleases
  • GTP Phosphohydrolases
  • NRAS protein, human
  • 17-aminogeldanamycin
  • geldanamycin