Abstract
Aim:
To investigate the role of LKB1 in regulation of mTOR signaling in non-small cell lung cancer (NSCLC) cells.
Methods:
LKB1 protein expression and phosphorylation of AMPK, 4E-BP1 and S6K in the cells were assessed using Western blotting in various NSCLC cell lines (A549, H460, H1792, Calu-1 and H1299). Energy stress was mimicked by treating the cells with 2-deoxyglucose (2-DG). Compound C was used to inhibit AMPK activity. Cell growth was measured using the MTS assay.
Results:
LKB1 protein was expressed in LKB1 wild-type Calu-1, H1299 and H1792 cells, but it was undetected in LKB1 mutant A549 and H460 cells. Treatment of the LKB1 wild-type cells with 2-DG (5, 10 and 25 mmol/L) augmented the phosphorylation of AMPK in dose- and time-dependent manners. In the LKB1 wild-type cells, 2-DG dramatically suppressed the phosphorylation of two mTOR targets, 4E-BP1 and S6K, whereas the LKB1 mutant A549 and H460 cells were highly resistant to 2-DG-induced inhibition on mTOR activity. In addition, stable knockdown of LKB1 in H1299 cells impaired 2-DG-induced inhibition on mTOR activity. Pretreatment of H1299 and H1792 cells with the AMPK inhibitor compound C (10 μmol/L) blocked 2-DG-induced inhibition on mTOR activity. 2-DG inhibited the growth of H1299 cells more effectively than that of H460 cells; stable knockdown of LKB1 in H1299 cells attenuated the growth inhibition caused by 2-DG.
Conclusion:
In non-small cell lung cancer cells, LKB1/AMPK signaling negatively regulates mTOR activity and contributes to cell growth inhibition in response to energy stress.
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Acknowledgements
The project was supported by grants from the National Natural Science Foundation of China (No 30971307 and No 81071915) and the Tianjin Natural Science Foundation (No 10JCYBJC13700).
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Dong, Lx., Sun, Ll., Zhang, X. et al. Negative regulation of mTOR activity by LKB1-AMPK signaling in non-small cell lung cancer cells. Acta Pharmacol Sin 34, 314–318 (2013). https://doi.org/10.1038/aps.2012.143
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DOI: https://doi.org/10.1038/aps.2012.143
