HuR posttranscriptionally regulates WEE1: implications for the DNA damage response in pancreatic cancer cells.

Abstract

HuR (ELAV1), an RNA-binding protein abundant in cancer cells, primarily resides in the nucleus, but under specific stress (e.g., gemcitabine), HuR translocates to the cytoplasm in which it tightly modulates the expression of mRNA survival cargo. Here, we demonstrate for the first time that stressing pancreatic ductal adenocarcinoma (PDA) cells by treatment with DNA-damaging anticancer agents (mitomycin C, oxaliplatin, cisplatin, carboplatin, and a PARP inhibitor) results in HuR's translocation from the nucleus to the cytoplasm. Importantly, silencing HuR in PDA cells sensitized the cells to these agents, whereas overexpressing HuR caused resistance. HuR's role in the efficacy of DNA-damaging agents in PDA cells was, in part, attributed to the acute upregulation of WEE1 by HuR. WEE1, a mitotic inhibitor kinase, regulates the DNA damage repair pathway, and therapeutic inhibition of WEE1 in combination with chemotherapy is currently in early phase trials for the treatment of cancer. We validate WEE1 as a HuR target in vitro and in vivo by demonstrating (i) direct binding of HuR to WEE1's mRNA (a discrete 56-bp region residing in the 3' untranslated region) and (ii) HuR siRNA silencing and overexpression directly affects the protein levels of WEE1, especially after DNA damage. HuR's positive regulation of WEE1 increases γ-H2AX levels, induces Cdk1 phosphorylation, and promotes cell-cycle arrest at the G2-M transition. We describe a novel mechanism that PDA cells use to protect against DNA damage in which HuR posttranscriptionally regulates the expression and downstream function of WEE1 upon exposure to DNA-damaging agents.

• Authors: Shruti Lal, Richard A Burkhart, Neil Beeharry, Vikram Bhattacharjee, Eric R Londin, Joseph A Cozzitorto, Carmella Romeo, Masaya Jimbo, Zoë A Norris, Charles J Yeo, Janet A Sawicki, Jordan M Winter, Isidore Rigoutsos, Timothy J Yen, Jonathan R Brody
• Journal: Cancer research (Cancer Res) Vol. 74 Issue 4 Pg. 1128-40 (Feb 15 2014) ISSN: 1538-7445 [Electronic] United States
• PMID: 24536047 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: ©2014 AACR.

Chemical References

• Antineoplastic Agents
• Cell Cycle Proteins
• ELAV Proteins
• Nuclear Proteins
• Protein-Tyrosine Kinases
• WEE1 protein, human

Topics

• Animals
• Antineoplastic Agents (pharmacology)
• Carcinoma, Pancreatic Ductal (genetics, metabolism)
• Cell Cycle Proteins (genetics, metabolism)
• DNA Damage (physiology)
• ELAV Proteins (physiology)
• Gene Expression Regulation, Neoplastic
• Humans
• Mice
• Nuclear Proteins (genetics, metabolism)
• Pancreatic Neoplasms (genetics, metabolism)
• Protein Transport (drug effects)
• Protein-Tyrosine Kinases (genetics, metabolism)
• RNA Interference
• Tumor Cells, Cultured