Identification of de novo enhancers activated by tgfβ to drive expression of CDKN2A and B in hela cells

Yen Ting Liu, Lin Xu, Lynda Bennett, Jared C. Hooks, Jing Liu, Qinbo Zhou, Priscilla Liem, Yanbin Zheng, Stephen X. Skapek

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Disruption of the CDKN2A (INK4A/ARF) and B (INK4B) genes, which encode three function-independent tumor suppressors, is one of the most common events in human cancer. Because their relative importance in tumor prevention appears to be species- and context-specific, studying their regulation can shed light on mechanisms by which they are bypassed in malignant transformation. We previously unveiled a new pathway in which TGFβ selectively induces Arf at mouse Cdkn2a in eye development and cultured fibroblasts. As TGFβ signaling is often derailed in cancer development or progression, we investigated its control of CDKN2A/B in human cancer. Computational analyses of sequencing and array data from nearly 11,000 patients with cancer in TCGA showed discordant expression of ARF and INK4A in most cancer subtypes, with gene copy-number loss and promoter methylation involved in only a subset. Using HeLa cells as a model, we found that exogenous TGFβ induced ARF mRNA and protein, and ARF knockdown limited TGFβ-mediated growth suppression. TGFβ-mediated ARF mRNA induction required SMAD2/3, p38MAPK, and SP1, and ARF mRNA was induced without added RNAPII recruitment. Chromatin immunoprecipitation unveiled a remote enhancer element engaged by TGFβ by a mechanism that partially depended on p38MAPK. CRISPR-based editing of this enhancer limited induction of ARF and INK4B by TGFβ, but not by oncogenic RAS.

Original languageEnglish (US)
Pages (from-to)1854-1866
Number of pages13
JournalMolecular Cancer Research
Volume17
Issue number9
DOIs
StatePublished - 2019

ASJC Scopus subject areas

  • Molecular Biology
  • Oncology
  • Cancer Research

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