Abstract 6201: Early-onset CRC, vitamin A deficiency, and stem cell origin of cancer

Abstract The recent surge in early-onset CRC (EOCRC) has been attributed to a Westernized lifestyle, but the underlying molecular mechanism is largely unknown. In our cancer genetics clinic, we provide care for 10-20 young (50 age) CRC patients per year. But, only a fraction (~15%) of these young CRC patients are found to have CRC-predisposing germline mutations which doesn’t provide a hereditary factor that can explain EOCRC. Other genetic studies have found that the spectrum of somatic alterations was largely comparable between EOCRC and adult-onset CRC, particularly common are mutations occurring in APC and other members of the WNT pathway. Since a genetic etiology has not turned-up, we are exploring possible lifestyle factors. We hypothesize that vitamin A (retinol) deficiency is a likely etiologic factor because vitamin A is an essential nutrient that is not made by the human body. Thus, young individuals might be prone to any cancer-initiating effects of a vitamin A deficient diet. Indeed, many population-based studies (including ones on well-nourished populations) have reported a high prevalence of vitamin A deficiency in pre-school-aged children. Since APC mutation commonly occurs in early-onset CRCs, we conjecture that vitamin A (retinol) metabolism and APC mutation-induced activation of WNT signaling may be co-factors in promoting EOCRC. Accordingly, we have been investigating whether there is a functional connection between WNT and vitamin A/retinoic acid (RA) signaling, and if APC mutation generates an imbalance in a WNT: RA-linked mechanism that contributes to CRC development by impeding retinoid-induced colonic stem cell (SC) differentiation. We previously reported that RA signaling mainly occurs in aldehyde dehydrogenase-positive (ALDH+) SCs and that APC mutation leads to overpopulation of ALDH+ SCs and incomplete differentiation during CRC development. Thus, our findings suggest that APC mutation attenuates RA signaling in ALDH+ SCs, which might explain how vitamin A deficiency contributes to EOCRC development. Citation Format: Bruce M. Boman, Victoria O. Hunsu, Caroline O. Facey. Early-onset CRC, vitamin A deficiency, and stem cell origin of cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 6201.