Histological evaluation of AMPK signalling in primary breast cancer.
BACKGROUND
AMP-activated protein kinase (AMPK) acts as a cellular fuel gauge that responds to energy stress by suppressing cell growth and biosynthetic processes, thus ensuring that energy-consuming processes proceed only if there are sufficient metabolic resources. Malfunction of the AMPK pathway may allow cancer cells to undergo uncontrolled proliferation irrespective of their molecular energy levels. The aim of this study was to examine the state of AMPK phosphorylation histologically in primary breast cancer in relation to clinical and pathological parameters.


METHODS
Immunohistochemistry was performed using antibodies to phospho-AMPK (pAMPK), phospho-Acetyl Co-A Carboxylase (pACC) an established target for AMPK, HER2, ERalpha, and Ki67 on Tissue Micro-Array (TMA) slides of two cohorts of 117 and 237 primary breast cancers. The quick score method was used for scoring and patterns of protein expression were compared with clinical and pathological data, including a minimum 5 years follow up.


RESULTS
Reduced signal, compared with the strong expression in normal breast epithelium, using a pAMPK antibody was demonstrated in 101/113 (89.4%) and 217/236 (91.9%) of two cohorts of patients. pACC was significantly associated with pAMPK expression (p = 0.007 & p = 0.014 respectively). For both cohorts, reduced pAMPK signal was significantly associated with higher histological grade (p = 0.010 & p = 0.021 respectively) and axillary node metastasis (p = 0.061 & p = 0.039 respectively). No significant association was found between pAMPK and any of HER2, ERalpha, or Ki67 expression, disease-free survival or overall survival.


CONCLUSIONS
This study extends in vitro evidence through immunohistochemistry to confirm that AMPK is dysfunctional in primary breast cancer. Reduced signalling via the AMPK pathway, and the inverse relationship with histological grade and axillary node metastasis, suggests that AMPK re-activation could have therapeutic potential in breast cancer.
Hadad
Sirwan M
SM
Department of Surgery and Molecular Oncology, Ninewells Hospital and Medical School, Dundee, UK. s.hadad@dundee.ac.uk
Baker
Lee
L
Quinlan
Philip R
PR
Robertson
Katherine E
KE
Bray
Susan E
SE
Thomson
George
G
Kellock
David
D
Jordan
Lee B
LB
Purdie
Colin A
CA
Hardie
David G
DG
Fleming
Stewart
S
Thompson
Alastair M
AM
D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000378:metabolism*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D010766:Phosphorylation; D015398:Signal Transduction
D055372:AMP-Activated Protein Kinases