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Makhov P , Golovine K , Teper E , Kutikov A , Mehrazin R , Corcoran A , Tulin A , Uzzo RG , Kolenko VM
Piperlongumine promotes autophagy via inhibition of Akt/mTOR signalling and mediates cancer cell death
Br J Cancer. 2014 Feb 18;110(4) :899-907
PMID: 24434432    PMCID: PMC3929888   
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BACKGROUND: The Akt/mammalian target of rapamycin (mTOR) signalling pathway serves as a critical regulator of cellular growth, proliferation and survival. Akt aberrant activation has been implicated in carcinogenesis and anticancer therapy resistance. Piperlongumine (PL), a natural alkaloid present in the fruit of the Long pepper, is known to exhibit notable anticancer effects. Here we investigate the impact of PL on Akt/mTOR signalling. METHODS: We examined Akt/mTOR signalling in cancer cells of various origins including prostate, kidney and breast after PL treatment. Furthermore, cell viability after concomitant treatment with PL and the autophagy inhibitor, Chloroquine (CQ) was assessed. We then examined the efficacy of in vivo combination treatment using a mouse xenograft tumour model. RESULTS: We demonstrate for the first time that PL effectively inhibits phosphorylation of Akt target proteins in all tested cells. Furthermore, the downregulation of Akt downstream signalling resulted in decrease of mTORC1 activity and autophagy stimulation. Using the autophagy inhibitor, CQ, the level of PL-induced cellular death was significantly increased. Moreover, concomitant treatment with PL and CQ demonstrated notable antitumour effect in a xenograft mouse model. CONCLUSIONS: Our data provide novel therapeutic opportunities to mediate cancer cellular death using PL. As such, PL may afford a novel paradigm for both prevention and treatment of malignancy.
Makhov, P Golovine, K Teper, E Kutikov, A Mehrazin, R Corcoran, A Tulin, A Uzzo, R G Kolenko, V M R01 CA134463/CA/NCI NIH HHS/United States R03 CA167671/CA/NCI NIH HHS/United States Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. England Br J Cancer. 2014 Feb 18;110(4):899-907. doi: 10.1038/bjc.2013.810. Epub 2014 Jan 16.