C39
A-769662 is an AMP Kinase-dependant growth inhibitor in breast cancer cell lines
Sirwan Hadad, Virginia Appleyard, Karen Murray, Lee Baker, Xu Huang, Dario Alessi, Alastair Thompson
University of Dundee, Dundee, UK
Background
The antidiabetic drug metformin has been linked to a reduced incidence of breast cancer and has a growth inhibitory effect in breast cancer cells through an LKB1-dependant activation of AMP-activated protein kinase (AMPK). The new formulated compound A-769662 (Abbott) reduces plasma glucose and body weight gain through direct activation of AMPK in vivo. The aim of this study was to identify the effect of A-769662 on breast cancer cell lines, and whether any effect is through the LKB1-AMPK signalling pathway.
Method
MCF-7 (ER+, LKB1+), MDA-MB-231 (ER-, reported LKB1-), and ZR-75-30 (ER-, LKB1+) cells were cultured to 70% confluence, then treated with 0, 20, 40, 80 and 160µM of A-769662; and 0, 2.5, 5, 10 and 20mM of metformin. Cell proliferation colorimetric MTT assays and western blots for phospho-AMPK, phospho-Acetyl-CoA Carboxylase (ACC), along with their total proteins, and western blot for total LKB1 and LKB1 kinase activity assay were performed.
Results
A-769662 significantly reduced MCF7 and MDA-MB-231 cell proliferation in a dose-dependant manner, reaching 49.8% and 32.8% of control at 160μM respectively (p<0.001), but had no effect on ZR-75-30. Metformin suppressed cell proliferation in all 3 cell types, was also dose-dependant but the effect on ZR-75-30 was less dramatic (8.41%) compared to the other two cell types (58.95% and 42.13% for MCF-7 and MDA-MB-231 at 20mM respectively, p<0.001). For both A-769662 and metformin, increased growth suppression was associated with AMPK and ACC phosphorylation; and where there was no effect, there was no phosphorylation. Interestingly, despite relatively less growth suppression of A-769662 compared to metformin, AMPK and ACC phosphorylation was greater. Moreover, LKB1 was found present in all three cell types, but more active in MCF-7 cells compared to the other two cell types (p=0.002).
Conclusion
A-769662 and metformin are dose-dependant growth inhibitors in both ER positive and ER negative breast cancer cells. Their effect is relatively less, or even negligible, on ER negative/dormant LKB1 breast cancer cells. Whether this is due to LKB1 activity alone is unclear. However, the effect is linear with the drug’s ability to activate the AMPK signalling pathway. The anti-neoplastic properties of A-769662 and metformin warrant further studies.
