Combination of Honokiol and Radiation in Colon Cancer Therapy

Colorectal cancer is the second most common cause of cancer deaths in humans, with about 5% of the U.S. population developing colorectal cancer in their lifetimes. Current treatment for colorectal cancer is surgical resection, combined with chemo and radiation therapy. Because this therapy is only moderately successful, novel approaches to the treatment of colorectal cancer are required.  The phytochemical honokiol is a natural extract from the leaves and the root stems of the Magnolia plant that has long been used in traditional Asian medicine to treat thrombotic and gastrointestinal disorders. There is some evidence that honokiol inhibits cancer cell growth. For this reason, we began looking at the combination effect of honokiol and radiation on colon cancer cells. We have determined in preliminary studies that honokiol in combination with radiation inhibit colon cancer cell growth. We have identified that the Notch-1 signaling pathway is upregulated in colon cancer cells and that inhibiting the activation of this pathway can induce autophagy (self eating), a novel form of cell death.  Our current proposal hypothesis is that the combination of honokiol and radiation affects Notch signaling to induce autophagy to inhibit colon cancer. We expect that the work will lead to a better understanding of the mechanism of inhibition and identify novel methods to stop or slow down colon cancer growth.