Cardiac glycosides inhibit p53 synthesis by a mechanism relieved by Src or MAPK inhibition.
p53 is regulated at multiple levels. We report here that p53, in multiple lines of human cancer cells, is down-regulated by cardiac glycoside drugs digoxin and ouabain, potent inhibitors of Na(+)/K(+)-ATPase. These drugs reduced the basal levels of p53 protein at nanomolar concentrations in a dose-, time-, and cancer cell line-dependent manner, but independent of p53 status of wild-type or mutant. The drugs also reduced the levels of p53 induced by its activators as well as p53 transfected into human cancer cells, regardless of its status. Interestingly, the drugs had no effect on endogenous p53 in two immortalized human cell lines. Mechanistically, p53 reduction occurred not at the mRNA levels but at the protein levels, as a result of reduced protein synthesis rather than enhanced degradation. The cellular sensitivity to drug-induced p53 reduction was not associated with the levels of alphasubunits of Na(+)/K(+)-ATPase in different cell lines. Although lowering extracellular K(+) did not reduce p53 as did ouabain and digoxin, it did potentiate both digoxin- and ouabain-induced p53 reduction in sensitive lines. Finally, p53 reduction seems to be triggered by activation of Src/mitogen-activated protein kinase (MAPK) signaling pathways upon drug binding to the Na(+)/K(+)-ATPase and can be completely blocked by the inhibitors of Src or MAP/ERK kinase. This is the first report that cardiac glycoside drugs, by initiating the Src/MAPK signaling pathways, reduce the p53 levels via inhibition of p53 protein synthesis. The drugs may be useful in the treatment of human cancers with a gain-of-function p53 mutation.
Wang
Zhen
Z
Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, Ann Arbor, 48109, USA.
Zheng
Min
M
Li
Zhichuan
Z
Li
Ruiguo
R
Jia
Lijun
L
Xiong
Xiufang
X
Southall
Noel
N
Wang
Shaomeng
S
Xia
Menghang
M
Austin
Christopher P
CP
Zheng
Wei
W
Xie
Zijian
Z
Sun
Yi
Y
D002301:Cardiac Glycosides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D008954:Models, Biological; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors*; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis* / Q000235:genetics
D002301:Cardiac Glycosides; D016159:Tumor Suppressor Protein p53; D016392:Proto-Oncogene Proteins pp60(c-src); D048049:Extracellular Signal-Regulated MAP Kinases
Nat Med. 2002 Mar;8(3):282-8
11875500
Am J Physiol. 1997 Dec;273(6):C2065-79
9435514
Nat Cell Biol. 2008 Sep;10(9):1098-105
19160491
Mol Cancer Ther. 2008 Jun;7(6):1533-42
18566224
Mol Carcinog. 2006 Jun;45(6):409-15
16652354
Cancer Biol Ther. 2008 Jun;7(6):845-52
18340116
Cancer Cell. 2006 Sep;10(3):191-202
16959611
Cancer Res. 2006 Jun 1;66(11):5867-74
16740726
Science. 1999 Dec 24;286(5449):2507-10
10617466
Oncogene. 2003 Jul 17;22(29):4478-87
12881704
Biol Pharm Bull. 2006 Jul;29(7):1493-7
16819197
Science. 1999 Sep 10;285(5434):1733-7
10481009
Proc Natl Acad Sci U S A. 2008 May 6;105(18):6638-43
18448675
Cancer Res. 2005 Aug 15;65(16):7386-92
16103091
Integr Cancer Ther. 2007 Dec;6(4):354-64
18048883
Histol Histopathol. 2008 Sep;23(9):1143-9
18581285
Am J Physiol. 1987 Feb;252(2 Pt 1):C179-89
3030119
Cell Death Differ. 2008 Jun;15(6):959-76
18356920
Proc Natl Acad Sci U S A. 2008 Dec 16;105(50):19579-86
19020076
Science. 2004 Feb 6;303(5659):844-8
14704432
Cancer Cell. 2005 Jun;7(6):547-59
15950904
Nat Med. 2004 Dec;10(12):1321-8
15558054
Mol Cell. 2003 Mar;11(3):577-90
12667443
Nat Rev Cancer. 2004 Oct;4(10):793-805
15510160
Gene. 2007 Jun 15;395(1-2):1-7
17395405
Nat Rev Drug Discov. 2008 Dec;7(12):979-87
19043449
Am J Physiol Cell Physiol. 2007 Aug;293(2):C509-36
17494630
J Biol Chem. 1996 Jan 12;271(2):695-701
8557675
EMBO J. 2007 Nov 28;26(23):4812-23
17962806
Mol Cell. 2008 Oct 24;32(2):180-9
18951086
Proc Natl Acad Sci U S A. 2008 Mar 11;105(10):3933-8
18316739
Crit Rev Oncol Hematol. 2006 Jun;58(3):190-207
16690321
Oncogene. 1995 Sep 7;11(5):933-9
7675452
Nat Rev Cancer. 2005 Sep;5(9):689-98
16110319
Lancet. 1979 Mar 10;1(8115):563
85158
Cancer Biol Ther. 2003 Jul-Aug;2(4):406-15
14508115
J Biol Chem. 2006 Jul 14;281(28):19709-19
16698801
Nat Cell Biol. 2007 May;9(5):573-80
17417627
Curr Opin Cell Biol. 2003 Apr;15(2):164-71
12648672
Cell. 2005 Oct 7;123(1):49-63
16213212
Cancer Res. 2008 Sep 15;68(18):7570-8
18794145
Science. 2004 Feb 13;303(5660):1010-4
14963330
Nature. 2000 Nov 16;408(6810):307-10
11099028
Mol Interv. 2003 May;3(3):157-68
14993422
Nat Chem Biol. 2006 Sep;2(9):474-9
16862141
Mol Interv. 2008 Feb;8(1):36-49
18332483
Mol Pharmacol. 2005 Mar;67(3):929-36
15602003
Clin Cancer Res. 2008 Oct 15;14(20):6376-86
18927276
BMC Cancer. 2001;1:11
11532201
Nature. 1998 Mar 26;392(6674):405-8
9537326