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Research Articles: Therapeutics, Targets, and Development

Antiproliferative effect of sulindac in colonic neoplasia prevention: role of COOH-terminal Src kinase

Department of Internal Medicine, Evanston Northwestern Healthcare Research Institute, Evanston, Illinois

Requests for reprints: Hemant K. Roy, Feinberg School of Medicine at Northwestern University, Department of Internal Medicine, Evanston Northwestern Healthcare, 2650 Ridge Avenue, Suite G208, Evanston, IL 60201. Phone: 847-570-2339; Fax: 847-733-5451. E-mail: h-roy{at}northWestern.edu

Abstract

Although the nonsteroidal anti-inflammatory drugs (NSAID) protection against colorectal cancer is well established, the molecular mechanisms remain unclear. We show herein that induction of the tumor suppressor gene COOH-terminal Src kinase (Csk) by NSAID is important for their antiproliferative and hence chemopreventive effects. In the azoxymethane-treated rat model of experimental colon carcinogenesis, sulindac treatment markedly induced Csk with a corresponding increase in inhibitory phosphorylation of Src (Tyr⁵²⁷). Sulindac-mediated Csk induction was replicated in the human colorectal cancer cell line HT-29, with a corresponding suppression of both Src kinase activity (63% of vehicle; P < 0.05) and E-cadherin tyrosine phosphorylation (an in vivo Src target). To determine the importance of Csk in NSAID antiproliferative activity, we stably transfected a Csk-specific short hairpin RNA (shRNA) vector into HT-29 cells, thereby blunting the sulindac-mediated Csk induction. These transfectants were significantly less responsive to the antiproliferative effect of sulindac sulfide (suppression of proliferating cell nuclear antigen was 21 ± 2.3% in transfectants versus 45 ± 4.23% in wild-type cells), with a corresponding mitigation of the sulindac-mediated G₁-S-phase arrest (S-phase cells 48 ± 3.6% versus 14 ± 2.8% of vehicle respectively). Importantly, the Csk shRNA cells had a marked decrease in the cyclin-dependent kinase inhibitor p21^cip/waf1, a critical regulator of G₁-S-phase progression (49% of wild-type cells). Moreover, although sulindac-mediated induction of p21^cip/waf1 was 113% in wild-type HT-29, this induction was alleviated in the Csk shRNA transfectants (65% induction; P < 0.01). Thus, this is the first demonstration that the antiproliferative activity of NSAID is modulated, at least partly, through the Csk/Src axis. [Mol Cancer Ther 2008;7(7):1797–806]

Grant support: U01CA111257.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Note: Presented in part in abstract form at the Digestive Disease Week Meeting, Washington, DC, May 2007.

Received 1/ 8/08; revised 3/12/08; accepted 3/16/08.