Colon Cancer Research Today is a free monthly online journal that collates and summarizes the latest research about Colon Cancer, including details on causes, treatment, symptoms.

Nitric oxide-donating aspirin induces apoptosis in human colon cancer cells through induction of oxidative stress.

Gao J, Liu X, Rigas B

Division of Cancer Prevention, Department of Medicine, Stony Brook University, Stony Brook, NY 11794-5200, USA.

Nitric oxide-donating aspirin (NO-ASA) is a promising chemoprevention agent against colon cancer and other cancers. It consists of traditional ASA to which a NO-releasing moiety is bound through a spacer. NO-ASA inhibits colon cancer cell growth several hundred times more potently than does ASA. In Min mice, NO-ASA inhibited intestinal carcinogenesis without affecting cell proliferation. Thus, we examined whether NO-ASA's most important cell kinetic effect is the induction of apoptosis. After confirming induction of apoptosis in Min mice, we studied the underlying mechanism in human colon adenocarcinoma cells. NO-ASA's spacer formed a conjugate with glutathione, depleting glutathione stores. This induced oxidative stress (increased intracellular levels of peroxides and O(2)(.-)) leads to apoptosis by activating the intrinsic apoptosis pathway. NO-ASA disrupted adherens junctions by inducing cleavage of beta- and gamma-catenin, resulting in cell detachment. NO-ASA inhibited Wnt signaling by a dual mechanism: at low concentrations it blocked the formation of beta-catenin/Tcf complexes (dominant mechanism), and at higher concentrations it also cleaved beta-catenin. These findings provide a mechanism of action by a potent chemopreventive agent, underscore the significance of these pathways in regulating cell death in the context of cancer chemoprevention, and present a paradigm for developing agents with enhanced cancer cell growth inhibitory properties.

Published 23 November 2005 in Proc Natl Acad Sci U S A, 102(47): 17207-12.
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