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Published on: June 27, 2017

Protein kinase Cepsilon interacts with Stat3 and regulates its activation that is essential for the development of

Moammir H Aziz1, Herbert T Manoharan, Jordan M Sand

  • 1Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53792, USA.

Molecular Carcinogenesis
|June 23, 2007
PubMed

Insights

Protein Kinase C epsilon (PKCepsilon) directly phosphorylates Signal Transducer and Activator of Transcription-3 (Stat3) at serine 727. This interaction is crucial for Stat3 activation and the development of squamous cell carcinoma (SCC) following UVR exposure.

Area of Science:

  • Dermatology
  • Molecular Biology
  • Cancer Research

Background:

  • Protein Kinase C (PKC) is a family of enzymes involved in cell signaling.
  • PKC isoforms, particularly PKCepsilon, are implicated in skin cancer development.
  • The precise mechanism linking PKCepsilon to skin cancer progression, specifically its interaction with Stat3, was unclear.

Purpose of the Study:

  • To elucidate the molecular mechanism by which PKCepsilon contributes to skin carcinogenesis.
  • To investigate the interaction between PKCepsilon and Signal Transducer and Activator of Transcription-3 (Stat3).
  • To determine if PKCepsilon directly regulates Stat3 activity.

Main Methods:

  • Utilized PKCepsilon overexpressing transgenic mice.
  • Applied 12-O-tetradecanoylphorbol-13-acetate (TPA) and ultraviolet radiation (UVR) as stimuli.
  • Employed immunoprecipitation, Western blotting, and immunofluorescence staining to assess protein interactions and localization.
  • Performed immunocomplex kinase assays to evaluate phosphorylation activity.
  • Used siRNA to deplete PKCepsilon and assess downstream effects on Stat3.

Main Results:

  • PKCepsilon interacts with Stat3 in a UVR-dependent manner.
  • PKCepsilon specifically phosphorylates Stat3 at the serine 727 residue.
  • PKCepsilon depletion inhibited Stat3 phosphorylation, DNA binding, and transcriptional activity.
  • PKCepsilon overexpression promoted cell survival and squamous cell carcinoma (SCC) development, correlating with Stat3 activation.

Conclusions:

  • PKCepsilon directly mediates Stat3 activation through phosphorylation at Ser727.
  • This PKCepsilon-Stat3 pathway is a key mechanism in UVR-induced skin carcinogenesis.
  • Targeting the PKCepsilon-Stat3 interaction may offer therapeutic strategies for preventing or treating skin cancer.

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