The RNA-Binding Protein HuR Posttranscriptionally Regulates the Protumorigenic Activator YAP1 in Pancreatic Ductal Adenocarcinoma

Mol Cell Biol. 2022 Jul 21;42(7):e0001822. doi: 10.1128/mcb.00018-22. Epub 2022 Jun 15.

Abstract

Yes-associated protein 1 (YAP1) is indispensable for the development of mutant KRAS-driven pancreatic ductal adenocarcinoma (PDAC). High YAP1 mRNA is a prognostic marker for worse overall survival in patient samples; however, the regulatory mechanisms that mediate its overexpression are not well understood. YAP1 genetic alterations are rare in PDAC, suggesting that its dysregulation is likely not due to genetic events. HuR is an RNA-binding protein whose inhibition impacts many cancer-associated pathways, including the "conserved YAP1 signature" as demonstrated by gene set enrichment analysis. Screening publicly available and internal ribonucleoprotein immunoprecipitation (RNP-IP) RNA sequencing (RNA-Seq) data sets, we discovered that YAP1 is a high-confidence target, which was validated in vitro with independent RNP-IPs and 3' untranslated region (UTR) binding assays. In accordance with our RNA sequencing analysis, transient inhibition (e.g., small interfering RNA [siRNA] and small-molecular inhibition) and CRISPR knockout of HuR significantly reduced expression of YAP1 and its transcriptional targets. We used these data to develop a HuR activity signature (HAS), in which high expression predicts significantly worse overall and disease-free survival in patient samples. Importantly, the signature strongly correlates with YAP1 mRNA expression. These findings highlight a novel mechanism of YAP1 regulation, which may explain how tumor cells maintain YAP1 mRNA expression at dynamic times during pancreatic tumorigenesis.

Keywords: HuR; PDAC; YAP1; pancreatic cancer; posttranscriptional regulation.

Publication types

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

MeSH terms

  • 3' Untranslated Regions / genetics
  • Carcinoma, Pancreatic Ductal* / genetics
  • Carcinoma, Pancreatic Ductal* / pathology
  • Cell Line, Tumor
  • ELAV-Like Protein 1 / genetics
  • ELAV-Like Protein 1 / metabolism
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Pancreatic Neoplasms* / genetics
  • Pancreatic Neoplasms* / pathology
  • RNA, Messenger / genetics
  • RNA, Small Interfering
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • YAP-Signaling Proteins

Substances

  • 3' Untranslated Regions
  • ELAV-Like Protein 1
  • ELAVL1 protein, human
  • RNA, Messenger
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • YAP-Signaling Proteins
  • YAP1 protein, human