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Proc Natl Acad Sci U S A. 2014 Jan 21;111(3):1114-9. doi: 10.1073/pnas.1319551111. Epub 2014 Jan 6.

Frequent mutation of receptor protein tyrosine phosphatases provides a mechanism for STAT3 hyperactivation in head and neck cancer.

Author information

1
Departments of Otolaryngology, Pharmacology and Chemical Biology, Structural Biology, and Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213.

Abstract

The underpinnings of STAT3 hyperphosphorylation resulting in enhanced signaling and cancer progression are incompletely understood. Loss-of-function mutations of enzymes that dephosphorylate STAT3, such as receptor protein tyrosine phosphatases, which are encoded by the PTPR gene family, represent a plausible mechanism of STAT3 hyperactivation. We analyzed whole exome sequencing (n = 374) and reverse-phase protein array data (n = 212) from head and neck squamous cell carcinomas (HNSCCs). PTPR mutations are most common and are associated with significantly increased phospho-STAT3 expression in HNSCC tumors. Expression of receptor-like protein tyrosine phosphatase T (PTPRT) mutant proteins induces STAT3 phosphorylation and cell survival, consistent with a "driver" phenotype. Computational modeling reveals functional consequences of PTPRT mutations on phospho-tyrosine-substrate interactions. A high mutation rate (30%) of PTPRs was found in HNSCC and 14 other solid tumors, suggesting that PTPR alterations, in particular PTPRT mutations, may define a subset of patients where STAT3 pathway inhibitors hold particular promise as effective therapeutic agents.

KEYWORDS:

STAT3 activation; driver mutations; phosphatase mutations

PMID:
24395800
PMCID:
PMC3903220
DOI:
10.1073/pnas.1319551111
[Indexed for MEDLINE]
Free PMC Article

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