Steroids up-regulate p66Shc longevity protein in growth regulation by inhibiting its ubiquitination.
BACKGROUND
p66Shc, an isoform of Shc adaptor proteins, mediates diverse signals, including cellular stress and mouse longevity. p66Shc protein level is elevated in several carcinomas and steroid-treated human cancer cells. Several lines of evidence indicate that p66Shc plays a critical role in steroid-related carcinogenesis, and steroids play a role in its elevated levels in those cells without known mechanism.


RESULTS
In this study, we investigated the molecular mechanism by which steroid hormones up-regulate p66Shc protein level. In steroid-treated human prostate and ovarian cancer cells, p66Shc protein levels were elevated, correlating with increased cell proliferation. These steroid effects on p66Shc protein and cell growth were competed out by the respective antagonist. Further, actinomycin D and cyclohexamide could only partially block the elevated p66Shc protein level by steroids. Treatment with proteasomal inhibitors, but not lysosomal protease inhibitor, resulted in elevated p66Shc protein levels, even higher than that by steroids. Using prostate cancer cells as a model, immunoprecipitation revealed that androgens and proteasomal inhibitors reduce the ubiquitinated p66Shc proteins.


CONCLUSIONS
The data collectively indicate that functional steroid receptors are required in steroid up-regulation of p66Shc protein levels in prostate and ovarian cancer cells, correlating with cell proliferation. In these steroid-treated cells, elevated p66Shc protein level is apparently in part due to inhibiting its ubiquitination. The results may lead to an impact on advanced cancer therapy via the regulation of p66Shc protein by up-regulating its ubiquitination pathway.
Department of Biochemistry and Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
Santosh
S
Kumar
Satyendra
S
Kumar
Mythilypriya
M
Rajendran
Syed Mahfuzul
SM
Alam
Fen-Fen
FF
Lin
Pi-Wan
PW
Cheng
Ming-Fong
MF
Lin
D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D010051:Ovarian Neoplasms / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D011987:Receptors, Steroid / Q000502:physiology; D055765:Shc Signaling Adaptor Proteins / Q000235:genetics* / Q000378:metabolism; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013256:Steroids / Q000494:pharmacology*; D054875:Ubiquitination / Q000187:drug effects*; D015854:Up-Regulation / Q000187:drug effects*
D011987:Receptors, Steroid; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013256:Steroids
Breast Cancer Res Treat. 1998 May;49(2):119-28
9696394
Oncogene. 2002 May 30;21(24):3872-8
12032825
Nat Rev Mol Cell Biol. 2003 Jun;4(6):491-7
12778128
Science. 1989 Mar 24;243(4898):1576-83
2538923
Clin Cancer Res. 2007 Oct 1;13(19):5798-804
17908971
J Biol Chem. 2002 Jul 19;277(29):26321-6
12015321
Mol Biol Cell. 2006 Jan;17(1):122-9
16251354
Annu Rev Biochem. 1999;68:1015-68
10872471
J Biol Chem. 1998 Mar 6;273(10):5939-47
9488733
Endocr Relat Cancer. 2009 Mar;16(1):1-16
19001530
Nature. 1993 May 6;363(6424):85-8
8479541
Annu Rev Biochem. 1998;67:425-79
9759494
Annu Rev Genet. 1996;30:405-39
8982460
Oncogene. 2005 Nov 3;24(48):7203-12
16170380
Nat Rev Mol Cell Biol. 2001 Mar;2(3):195-201
11265249
J Biol Chem. 2002 Jun 21;277(25):22370-6
11948181
Cancer Res. 2003 Oct 15;63(20):6772-83
14583473
Biochem Biophys Res Commun. 1996 Apr 5;221(1):140-5
8660324
Endocrinology. 2005 May;146(5):2473-80
15705774
Cell. 2004 Jan 23;116(2):181-90
14744430
Int J Cancer. 2004 Feb 20;108(5):672-8
14696093
EMBO J. 1997 Feb 17;16(4):706-16
9049300
Br J Cancer. 2007 Aug 6;97(3):277-82
17637683
J Biol Chem. 1987 Jun 15;262(17):8303-13
3298229
Oncogene. 2001 Oct 1;20(44):6322-30
11607835
J Biol Chem. 1998 Aug 21;273(34):22096-104
9705354
Arch Biochem Biophys. 2009 Jun 1;486(1):73-80
19327338
Oncogene. 2008 Aug 28;27(37):5057-68
18504439
Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):2112-6
12571362
Biochem Biophys Res Commun. 2003 Jul 18;307(1):188-97
12849999
Clin Cancer Res. 2000 Mar;6(3):1135-9
10741744
Trends Biochem Sci. 1996 Jul;21(7):267-71
8755249
Nature. 1999 Nov 18;402(6759):309-13
10580504
J Biol Chem. 1998 Apr 10;273(15):8545-8
9535824
J Biol Chem. 1990 Mar 25;265(9):4789-92
2180950
Proc Natl Acad Sci U S A. 1998 Jun 23;95(13):7625-30
9636200
Science. 2002 Mar 29;295(5564):2450-2
11884717
Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):2727-30
9501156
J Biol Chem. 2004 Oct 15;279(42):43900-9
15262993
J Biol Chem. 2002 Sep 27;277(39):36570-6
12119296
J Biol Chem. 2004 Jan 16;279(3):2299-306
14573619
J Biol Chem. 1987 Feb 25;262(6):2451-7
3029081
Prostate. 2002 Mar 1;50(4):222-35
11870800
Proc Natl Acad Sci U S A. 1989 Oct;86(20):7751-5
2554287