Harnessing the power of p53 with Panaxynol from American Ginseng to suppress colitis and prevent colon cancer

Affecting upwards of 4 million people in North America and Europe, with an economic burden of $30 $45 billion, Inflammatory Bowel Diseases (IBDs) are debilitating, significantly affect life-style, and carry a high colon cancer risk. Because conventional treatment outcomes are modest with dangerous side effects, about half of IBD patients turn to complementary and alternative medicines (CAMs). Although CAMs have been used for thousands of years, there is a gap in our knowledge of the mechanisms supporting their effectiveness. Understanding these mechanisms will lead to standardized treatment for IBD outside of toxic FDA-approved drugs. This will lower their colon cancer risk. Over the past decade, we have shown that American Ginseng (AG) suppresses colitis and prevents colon cancer in mice. Using scientifically rigorous Bioassay-Guided Fractionation, we have isolated a polyacetylene called panaxynol (PA) that has anti-inflammatory and anti-cancer properties. PA (compared to the100's of other CAMs being tested) comes from a natural source, and is a single ingredient, allowing it to be standardized on its own, or in a cocktail. What makes this molecule particularly interesting and innovative is the mechanism - it is a single molecule extracted from AG, with a unique capacity to target macrophages (mΦ) for apoptosis. Our long-term goal is to identify the primary component(s) of AG responsible for the robust anti-inflammatory and chemopreventive properties of AG we have observed over the past decade; and to determine their mechanism of action. The overall objective of this application is to gain a deeper understanding of both: (a) the broad treatment potential of PA (i.e. multiple pharmacologic and bioengineered animal models of colitis and colon cancer); and (b) the underlying mechanism(s) behind the observation that PA targets mΦ for apoptosis. We focus here on a DNA-damage independent p53 signaling pathway as a mechanism toward mΦ apoptosis. The scientific premise underlying the proposed research is robust. Comparing nine FDA-approved drugs, small molecules, and CAMs, PA is the most efficacious at suppressing colitis in a DSS mouse model. Our central hypothesis is that PA, isolated after a decade of rigorous bioassay-guided fractionation, has anti-inflammatory and anti-cancer activity in the colon because it activates p53- mediated apoptosis in infiltrating mΦ; mitigating colitis; and preventing colon cancer associated with colitis. Furthermore, PA acts as an anti-inflammatory in these models because it induces p53 through a DNA damagelike signaling response in mΦ that is independent of detectable DNA damage. To address this hypothesis, we will test the efficacy of PA in three mouse models of colitis and in genetically engineered mice. Because it appears that PA is taking advantage of a unique p53 mechanism in mΦ, we will test PA in mice with p53 conditionally knocked out in colonic mΦ. A DNA damage-independent mechanism is explored. Results consistent with our hypothesis would identify an innovative, low cost, safe, specific, and natural compound with anti-inflammatory and cancer chemopreventive properties that could quickly be implemented clinically.