TY - JOUR
T1 - Cardiac glycoside ouabain induces autophagic cell death in non-small cell lung cancer cells via a JNK-dependent decrease of Bcl-2
AU - Trenti, Annalisa
AU - Grumati, Paolo
AU - Cusinato, Federico
AU - Orso, Genny
AU - Bonaldo, Paolo
AU - Trevisi, Lucia
PY - 2014/5/15
Y1 - 2014/5/15
N2 - Cardiac glycosides are Na/K-ATPase inhibitors, clinically used for congestive heart failure and cardiac arrhythmias. Epidemiological studies have reported that patients on cardiac glycosides treatment are protected from some types of cancers. This evidence together with the demonstration that cardiac glycosides show selective cytotoxicity against cancer cells has raised new interest on the anticancer properties of these drugs. This study examines the mechanism involved in the anticancer effect of ouabain in non-small cell lung cancer cells lines (A549 and H1975). Ouabain inhibited cell proliferation and induced cell death in a concentration-dependent manner. Cell death was caspase-independent and showed classical patterns of autophagic cell death: conversion of LC3-I to LC3-II, increase of LC3 puncta and increase of autophagic flux. Moreover, cell death was completely blocked by the class III phosphatidylinositol-3 kinase inhibitor 3-methyladenine. Here we show that ouabain caused the reduction of Bcl-2 protein levels, with no change in the expression of the autophagic protein Beclin 1. Early signalling events of ouabain exposure were ERK1/2 and JNK activation, however only JNK inhibition with SP600125 or JNK knockdown by shRNA were able to prevent Bcl-2 decrease, conversion of LC3-I to LC3-II and cell death. We propose that JNK activation by ouabain leads to a decrease of Bcl-2 levels, resulting in disruption of the inhibitory interaction of Bcl-2 with Beclin 1, that promotes autophagy. These findings indicate that pharmacological modulation of autophagy by cardiac glycosides could be exploited for anticancer therapy.
AB - Cardiac glycosides are Na/K-ATPase inhibitors, clinically used for congestive heart failure and cardiac arrhythmias. Epidemiological studies have reported that patients on cardiac glycosides treatment are protected from some types of cancers. This evidence together with the demonstration that cardiac glycosides show selective cytotoxicity against cancer cells has raised new interest on the anticancer properties of these drugs. This study examines the mechanism involved in the anticancer effect of ouabain in non-small cell lung cancer cells lines (A549 and H1975). Ouabain inhibited cell proliferation and induced cell death in a concentration-dependent manner. Cell death was caspase-independent and showed classical patterns of autophagic cell death: conversion of LC3-I to LC3-II, increase of LC3 puncta and increase of autophagic flux. Moreover, cell death was completely blocked by the class III phosphatidylinositol-3 kinase inhibitor 3-methyladenine. Here we show that ouabain caused the reduction of Bcl-2 protein levels, with no change in the expression of the autophagic protein Beclin 1. Early signalling events of ouabain exposure were ERK1/2 and JNK activation, however only JNK inhibition with SP600125 or JNK knockdown by shRNA were able to prevent Bcl-2 decrease, conversion of LC3-I to LC3-II and cell death. We propose that JNK activation by ouabain leads to a decrease of Bcl-2 levels, resulting in disruption of the inhibitory interaction of Bcl-2 with Beclin 1, that promotes autophagy. These findings indicate that pharmacological modulation of autophagy by cardiac glycosides could be exploited for anticancer therapy.
KW - Autophagy
KW - Bcl-2
KW - Cardiac glycosides
KW - JNK
KW - Non-small cell lung cancer
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U2 - 10.1016/j.bcp.2014.02.021
DO - 10.1016/j.bcp.2014.02.021
M3 - Article
C2 - 24630927
AN - SCOPUS:84899437700
VL - 89
SP - 197
EP - 209
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
SN - 0006-2952
IS - 2
ER -