Prenylation inhibition-induced cell death in melanoma: reduced sensitivity in BRAF mutant/PTEN wild-type melanoma cells

PLoS One. 2015 Feb 3;10(2):e0117021. doi: 10.1371/journal.pone.0117021. eCollection 2015.

Abstract

While targeted therapy brought a new era in the treatment of BRAF mutant melanoma, therapeutic options for non-BRAF mutant cases are still limited. In order to explore the antitumor activity of prenylation inhibition we investigated the response to zoledronic acid treatment in thirteen human melanoma cell lines with known BRAF, NRAS and PTEN mutational status. Effect of zoledronic acid on proliferation, clonogenic potential, apoptosis and migration of melanoma cells as well as the activation of downstream elements of the RAS/RAF pathway were investigated in vitro with SRB, TUNEL and PARP cleavage assays and videomicroscopy and immunoblot measurements, respectively. Subcutaneous and spleen-to-liver colonization xenograft mouse models were used to evaluate the influence of zoledronic acid treatment on primary and disseminated tumor growth of melanoma cells in vivo. Zoledronic acid more efficiently decreased short-term in vitro viability in NRAS mutant cells when compared to BRAF mutant and BRAF/NRAS wild-type cells. In line with this finding, following treatment decreased activation of ribosomal protein S6 was found in NRAS mutant cells. Zoledronic acid demonstrated no significant synergism in cell viability inhibition or apoptosis induction with cisplatin or DTIC treatment in vitro. Importantly, zoledronic acid could inhibit clonogenic growth in the majority of melanoma cell lines except in the three BRAF mutant but PTEN wild-type melanoma lines. A similar pattern was observed in apoptosis induction experiments. In vivo zoledronic acid did not inhibit the subcutaneous growth or spleen-to-liver colonization of melanoma cells. Altogether our data demonstrates that prenylation inhibition may be a novel therapeutic approach in NRAS mutant melanoma. Nevertheless, we also demonstrated that therapeutic sensitivity might be influenced by the PTEN status of BRAF mutant melanoma cells. However, further investigations are needed to identify drugs that have appropriate pharmacological properties to efficiently target prenylation in melanoma cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Cell Line, Tumor
  • Cell Survival
  • Diphosphonates / therapeutic use*
  • GTP Phosphohydrolases / genetics
  • Humans
  • Imidazoles / therapeutic use*
  • Male
  • Melanoma / drug therapy*
  • Melanoma / genetics*
  • Melanoma / pathology
  • Membrane Proteins / genetics
  • Mice
  • Mice, SCID
  • Mutation*
  • PTEN Phosphohydrolase / genetics*
  • Prenylation / drug effects*
  • Proto-Oncogene Proteins B-raf / genetics*
  • Zoledronic Acid

Substances

  • Diphosphonates
  • Imidazoles
  • Membrane Proteins
  • Zoledronic Acid
  • Proto-Oncogene Proteins B-raf
  • PTEN Phosphohydrolase
  • GTP Phosphohydrolases
  • NRAS protein, human

Grants and funding

This work was financially supported by TAMOP 4.2.1/B-09/1/MKR-2010-0001, the National Innovation Office INNO 08-3-2009-0248, the Hungarian Science Foundation (OTKA) MOB 80325, PD109580, OTKA CNK77649, K84173 and the National Development Agency-NFU KTIA AIK 12-1-2013-0041 research grants and by the Herzfelder’schen Familienstiftung, Vienna. BH was a Magyary Zoltán postdoctoral fellow. GT acknowledges the Ernst Mach fellowship from the Österreichischer Austauschdienst. IK is a recipient of János Bolyai Research Scholarship of the Hungarian Academy of Sciences. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.