Melanoma Expressed-CD70 Is Regulated by RhoA and MAPK Pathways without Affecting Vemurafenib Treatment Activity

PLoS One. 2016 Feb 1;11(2):e0148095. doi: 10.1371/journal.pone.0148095. eCollection 2016.

Abstract

CD70 is a costimulatory molecule member of the Tumor Necrosis Factor family that is expressed on activated immune cells. Its ectopic expression has been described in several types of cancer cells including lymphomas, renal cell carcinomas and glioblastomas. We have recently described its expression in a part of tumor cells from the vast majority of melanoma biopsies and human melanoma cell lines, and found that CD70 expression decreased over time as the disease progressed. Here, we show that RhoA, BRAF and Mitogen Activating Protein Kinase pathways are involved in the positive transcriptional regulation of CD70 expression in melanomas. Interestingly, the clinical inhibitor of the common BRAF V600E/D variants, Vemurafenib (PLX-4032), which is currently used to treat melanoma patients with BRAF V600E/D-mutated metastatic melanomas, decreased CD70 expression in human CD70+ melanoma cell lines. This decrease was seen in melanoma cells both with and without the BRAFV600E/D mutation, although was less efficient in those lacking the mutation. But interestingly, by silencing CD70 in CD70+ melanoma cell lines we show that PLX-4032-induced melanoma cell killing and its inhibitory effect on MAPK pathway activation are unaffected by CD70 expression. Consequently, our work demonstrates that CD70 ectopic expression in melanomas is not a valuable biomarker to predict tumor cells sensitivity to BRAF V600 inhibitors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CD27 Ligand / metabolism*
  • Cell Line, Tumor
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cell Proliferation / drug effects
  • Gene Silencing / drug effects
  • Humans
  • Indoles / pharmacology
  • Indoles / therapeutic use*
  • MAP Kinase Signaling System* / drug effects
  • Melanoma / drug therapy*
  • Melanoma / enzymology*
  • Melanoma / genetics
  • Melanoma / pathology
  • Melanoma, Cutaneous Malignant
  • Proto-Oncogene Proteins B-raf / metabolism
  • Skin Neoplasms
  • Sulfonamides / pharmacology
  • Sulfonamides / therapeutic use*
  • Transcription, Genetic / drug effects
  • Vemurafenib
  • rhoA GTP-Binding Protein / metabolism*

Substances

  • CD27 Ligand
  • Indoles
  • Sulfonamides
  • Vemurafenib
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • rhoA GTP-Binding Protein

Grants and funding

This work was supported by the Institut National de la Santé et de la Recherche Médicale, La Ligue contre le Cancer, Association pour la Recherche contre le Cancer, Ministère de l’Enseignement Supérieur et de la Recherche, and Institut Claudius Regaud. The funder NeoVirTech provided support in the form of salaries for F Gallardo, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section.