SILAC-based phosphoproteomics reveals an inhibitory role of KSR1 in p53 transcriptional activity via modulation of DBC1
Author(s)
Type
Journal Article
Abstract
Background: We have previously identified kinase suppressor of ras-1 (KSR1) as a potential regulatory gene in breast cancer.
KSR1, originally described as a novel protein kinase, has a role in activation of mitogen-activated protein kinases. Emerging
evidence has shown that KSR1 may have dual functions as an active kinase as well as a scaffold facilitating multiprotein complex
assembly. Although efforts have been made to study the role of KSR1 in certain tumour types, its involvement in breast cancer
remains unknown.
Methods: A quantitative mass spectrometry analysis using stable isotope labelling of amino acids in cell culture (SILAC) was
implemented to identify KSR1-regulated phosphoproteins in breast cancer. In vitro luciferase assays, co-immunoprecipitation as
well as western blotting experiments were performed to further study the function of KSR1 in breast cancer.
Results: Of significance, proteomic analysis reveals that KSR1 overexpression decreases deleted in breast cancer-1 (DBC1)
phosphorylation. Furthermore, we show that KSR1 decreases the transcriptional activity of p53 by reducing the phosphorylation of
DBC1, which leads to a reduced interaction of DBC1 with sirtuin-1 (SIRT1); this in turn enables SIRT1 to deacetylate p53.
Conclusion: Our findings integrate KSR1 into a network involving DBC1 and SIRT1, which results in the regulation of p53
acetylation and its transcriptional activity
KSR1, originally described as a novel protein kinase, has a role in activation of mitogen-activated protein kinases. Emerging
evidence has shown that KSR1 may have dual functions as an active kinase as well as a scaffold facilitating multiprotein complex
assembly. Although efforts have been made to study the role of KSR1 in certain tumour types, its involvement in breast cancer
remains unknown.
Methods: A quantitative mass spectrometry analysis using stable isotope labelling of amino acids in cell culture (SILAC) was
implemented to identify KSR1-regulated phosphoproteins in breast cancer. In vitro luciferase assays, co-immunoprecipitation as
well as western blotting experiments were performed to further study the function of KSR1 in breast cancer.
Results: Of significance, proteomic analysis reveals that KSR1 overexpression decreases deleted in breast cancer-1 (DBC1)
phosphorylation. Furthermore, we show that KSR1 decreases the transcriptional activity of p53 by reducing the phosphorylation of
DBC1, which leads to a reduced interaction of DBC1 with sirtuin-1 (SIRT1); this in turn enables SIRT1 to deacetylate p53.
Conclusion: Our findings integrate KSR1 into a network involving DBC1 and SIRT1, which results in the regulation of p53
acetylation and its transcriptional activity
Date Issued
2013-11-12
Date Acceptance
2013-09-18
Citation
British Journal of Cancer, 2013, 109 (10), pp.2675-2684
ISSN
1532-1827
Publisher
Cancer Research UK
Start Page
2675
End Page
2684
Journal / Book Title
British Journal of Cancer
Volume
109
Issue
10
Copyright Statement
© 2013 Cancer Research UK. Under a Creative Commons Attribution Non-Commercial Share Alike License
Sponsor
National Institute for Health Research
Cancer Research UK
Grant Number
NIHR-RP-011-053
C27532/A14549
Subjects
Science & Technology
Life Sciences & Biomedicine
Oncology
ONCOLOGY
SILAC
KSR1
p53
DBC1
acetylation
ACTIVATED PROTEIN-KINASE
BREAST-CANCER
SIRT1 DEACETYLASE
GENE-EXPRESSION
DNA-DAMAGE
RAS
SUPPRESSOR
PHOSPHORYLATION
ACETYLATION
MECHANISM
Publication Status
Published