PROJECT SUMMARY/ABSTRACT A hallmark of colorectal cancers is the loss of the adenomatous polyposis coli (APC) tumor suppressor gene, resulting in dysregulated Wnt signaling and the oncogenic transformation of colon stem cells into cancer stem cells. In addition, inflammation, a major risk factor for the development of colorectal cancer, can upregulate cytokines that can drive the formation of tumor-initiating cells. Thus, strategies that target both inflammation and cancer stem cells may be effective in decreasing the risk of developing colorectal cancer. Sulforaphane, a naturally-occurring isothiocyanate derived from cruciferous vegetables and particularly abundant in broccoli, has well-established anti-inflammatory and anti-tumor activities. However, the precise mechanism by which it inhibits tumorigenesis and whether it is capable of reducing colorectal cancer risk remain to be determined. We have previously demonstrated that sulforaphane inhibits NFκB-mediated inflammatory responses in breast cancer cells as well as the proliferation and self-renewal capacity of breast cancer stem cells. We now have preliminary data strongly suggesting that sulforaphane has similar effects in colon cancer cells and more importantly, can inhibit the growth of human organoids driven by an APC mutation. Furthermore, mice fed a preparation of broccoli that is enriched in sulforaphane are more resistant to the development of colonic inflammation and adenoma formation. In this proposal, we will examine the efficacy of a pharmaceutical preparation of sulforaphane in suppressing the establishment of tumor-initiating cells driven by dysregulated Wnt signaling and determine its ability to inhibit colon stem cells capable of malignant transformation using in vivo mouse models and in vitro patient-derived organoid cultures. The proposed studies will be critical in developing a synthetic analog of sulforaphane as a chemopreventive agent in patients at high risk for developing colorectal cancer.