RBBP4-p300 axis modulates expression of genes essential for cell survival and is a potential target for therapy in glioblastoma

Ann C. Mladek, Huihuang Yan, Shulan Tian, Paul A. Decker, Danielle M. Burgenske, Katrina Bakken, Zeng Hu, Lihong He, Margaret A. Connors, Brett L. Carlson, Jonathan Wilson, Archana Bommi-Reddy, Andy Conery, Jeanette E. Eckel-Passow, Jann N. Sarkaria, Gaspar J. Kitange

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


BACKGROUND: RBBP4 activates transcription by histone acetylation, but the partner histone acetyltransferases are unknown. Thus, we investigated the hypothesis that RBBP4 interacts with p300 in a complex in glioblastoma (GBM).

METHODS: shRNA silencing of RBBP4 or p300 and RNAseq was used to identify genes co-regulated by RBBP4 and p300 in GBM43 patient-derived xenograft (PDX). RBBP4/p300 complex was demonstrated using proximity ligation assay (PLA) and ChIPseq delineated histone H3 acetylation and RBBP4/p300 complex binding in promoters/enhancers. Temozolomide (TMZ)-induced DNA double strand breaks (DSBs) were evaluated by γ-H2AX and proliferation by CyQuant and live cell monitoring assays. In vivo efficacy was based on survival of mice with orthotopic tumors.

RESULTS: shRBBP4 and shp300 downregulated 4768 genes among which 1485 (31%) were commonly downregulated by both shRNAs, while upregulated genes were 2484, including 863 (35%) common genes. The pro-survival genes were the top-ranked among the downregulated genes, including C-MYC. RBBP4/p300 complex was demonstrated in the nucleus, and shRBBP4 or shp300 significantly sensitized GBM cells to TMZ compared to the control shNT in vitro (P < .05). Moreover, TMZ significantly prolonged the survival of mice bearing GBM22-shRBBP4 orthotopic tumors compared with control shNT tumors (median shNT survival 52 days vs. median shRBBP4 319 days; P = .001). CREB-binding protein (CBP)/p300 inhibitor CPI-1612 suppressed H3K27Ac and RBBP4/p300 complex target proteins, including C-MYC, and synergistically sensitized TMZ in vitro. Pharmacodynamic evaluation confirmed brain penetration by CPI-1612 supporting further investigation to evaluate efficacy to sensitize TMZ.

CONCLUSIONS: RBBP4/p300 complex is present in GBM cells and is a potential therapeutic target.

Original languageEnglish (US)
Pages (from-to)1261-1272
Number of pages12
Issue number8
StatePublished - Aug 1 2022

Bibliographical note

Publisher Copyright:
© 2022 The Author(s). Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved.


  • glioblastoma
  • histone acetylation
  • RBB4/p300 complex
  • temozolomide
  • Retinoblastoma-Binding Protein 4/genetics
  • Promoter Regions, Genetic
  • E1A-Associated p300 Protein/genetics
  • Cell Survival
  • Humans
  • Drug Resistance, Neoplasm
  • Xenograft Model Antitumor Assays
  • Glioblastoma/drug therapy
  • Animals
  • Cell Line, Tumor
  • Mice
  • Acetylation
  • Temozolomide/pharmacology
  • Brain Neoplasms/drug therapy

PubMed: MeSH publication types

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


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