The mechanism by which aspirin consumption is linked to significant reductions in the incidence of multiple forms of cancer and metastatic spread to distant tissues, resulting in increased cancer patient survival is not well understood. In this study, using colon cancer as an example, we provide both in vitro (cell culture) and in vivo (chemically-induced mouse model of colon cancer) evidence that this profound anti-neoplastic action may be associated with aspirin's ability to irreversibly inhibit COX-1 mediated platelet activation, thereby blocking platelet-cancer cell interactions, which promote cancer cell number and invasive potential. This process may be driven by platelet-induced Epithelial-Mesenchymal Transition (EMT), as assessed using confocal microscopy, based upon changes in cell morphology, growth characteristics and fibronectin expression, and biochemical/molecular analysis by measuring changes in the expression of the EMT markers; vimentin, β-catenin, and SNAIL. We also provide evidence that a novel, GI-safer phosphatidylcholine (PC)-associated aspirin, PL2200 Aspirin, possesses the same or more pronounced actions vs unmodified aspirin with regard to antiplatelet effects (in vitro-reducing platelet activation as determined by measuring the release of thromboxane and VEGF release in culture medium; in vivo-inhibiting platelet number/activation and extravasation into tumor tissue) and chemoprevention (in vitro-inhibiting colonic cell growth, and invasive activity; in vivo-inhibiting colonic dysplasia, inflammation and tumor mass). These results suggest that aspirin's chemopreventive effects may be due, in part, to the drug blocking the pro-neoplastic action of platelets; and the potential use of Aspirin-PC/PL2200 as an effective and safer chemopreventive agent for colorectal cancer and possibly other cancers.
- Received September 15, 2016.
- Revision received November 29, 2016.
- Accepted November 30, 2016.
- Copyright ©2016, American Association for Cancer Research.