YAP and MRTF-A, transcriptional co-activators of RhoA-mediated gene expression, are critical for glioblastoma tumorigenicity

Oncogene. 2018 Oct;37(41):5492-5507. doi: 10.1038/s41388-018-0301-5. Epub 2018 Jun 11.

Abstract

The role of YAP (Yes-associated protein 1) and MRTF-A (myocardin-related transcription factor A), two transcriptional co-activators regulated downstream of GPCRs (G protein-coupled receptors) and RhoA, in the growth of glioblastoma cells and in vivo glioblastoma multiforme (GBM) tumor development was explored using human glioblastoma cell lines and tumor-initiating cells derived from patient-derived xenografts (PDX). Knockdown of these co-activators in GSC-23 PDX cells using short hairpin RNA significantly attenuated in vitro self-renewal capability assessed by limiting dilution, oncogene expression, and neurosphere formation. Orthotopic xenografts of the MRTF-A and YAP knockdown PDX cells formed significantly smaller tumors and were of lower morbidity than wild-type cells. In vitro studies used PDX and 1321N1 glioblastoma cells to examine functional responses to sphingosine 1-phosphate (S1P), a GPCR agonist that activates RhoA signaling, demonstrated that YAP signaling was required for cell migration and invasion, whereas MRTF-A was required for cell adhesion; both YAP and MRTF-A were required for proliferation. Gene expression analysis by RNA-sequencing of S1P-treated MRTF-A or YAP knockout cells identified 44 genes that were induced through RhoA and highly dependent on YAP, MRTF-A, or both. Knockdown of F3 (tissue factor (TF)), a target gene regulated selectively through YAP, blocked cell invasion and migration, whereas knockdown of HBEGF (heparin-binding epidermal growth factor-like growth factor), a gene selectively induced through MRTF-A, prevented cell adhesion in response to S1P. Proliferation was sensitive to knockdown of target genes regulated through either or both YAP and MRTF-A. Expression of TF and HBEGF was also selectively decreased in tumors from PDX cells lacking YAP or MRTF-A, indicating that these transcriptional pathways are regulated in preclinical GBM models and suggesting that their activation through GPCRs and RhoA contributes to growth and maintenance of human GBM.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics*
  • Animals
  • Brain Neoplasms / genetics
  • Brain Neoplasms / pathology*
  • Gene Expression Regulation, Neoplastic / genetics*
  • Glioblastoma / genetics
  • Glioblastoma / pathology*
  • Heterografts
  • Humans
  • Mice
  • Mice, Nude
  • Phosphoproteins / genetics*
  • Trans-Activators / genetics*
  • Transcription Factors
  • YAP-Signaling Proteins
  • rhoA GTP-Binding Protein / biosynthesis
  • rhoA GTP-Binding Protein / genetics

Substances

  • Adaptor Proteins, Signal Transducing
  • MRTFA protein, human
  • Phosphoproteins
  • Trans-Activators
  • Transcription Factors
  • YAP-Signaling Proteins
  • YAP1 protein, human
  • RHOA protein, human
  • rhoA GTP-Binding Protein