Rho-mediated signaling promotes BRAF inhibitor resistance in de-differentiated melanoma cells

Oncogene. 2020 Feb;39(7):1466-1483. doi: 10.1038/s41388-019-1074-1. Epub 2019 Oct 28.

Abstract

Over half of cutaneous melanoma tumors have BRAFV600E/K mutations. Acquired resistance to BRAF inhibitors (BRAFi) remains a major hurdle in attaining durable therapeutic responses. In this study we demonstrate that ~50-60% of melanoma cell lines with vemurafenib resistance acquired in vitro show activation of RhoA family GTPases. In BRAFi-resistant melanoma cell lines and tumors, activation of RhoA is correlated with decreased expression of melanocyte lineage genes. Using a machine learning approach, we built gene expression-based models to predict drug sensitivity for 265 common anticancer compounds. We then projected these signatures onto the collection of TCGA cutaneous melanoma and found that poorly differentiated tumors were predicted to have increased sensitivity to multiple Rho kinase (ROCK) inhibitors. Two transcriptional effectors downstream of Rho, MRTF and YAP1, are activated in the RhoHigh BRAFi-resistant cell lines, and resistant cells are more sensitive to inhibition of these transcriptional mechanisms. Taken together, these results support the concept of targeting Rho-regulated gene transcription pathways as a promising therapeutic approach to restore sensitivity to BRAFi-resistant tumors or as a combination therapy to prevent the onset of drug resistance.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Cell Dedifferentiation / drug effects*
  • Cell Line, Tumor
  • Enzyme Activation / drug effects
  • Humans
  • Melanocytes / drug effects
  • Melanocytes / pathology
  • Melanoma / pathology*
  • Protein Kinase Inhibitors / pharmacology*
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors*
  • Signal Transduction / drug effects*
  • Transcription Factors / metabolism
  • Transcription, Genetic / drug effects
  • YAP-Signaling Proteins
  • rho-Associated Kinases / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Protein Kinase Inhibitors
  • Transcription Factors
  • YAP-Signaling Proteins
  • YAP1 protein, human
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • rho-Associated Kinases