Abstract
NWD1, a purified rodent diet establishing mouse exposure to key nutrients recapitulating levels that increase risk for intestinal cancer, reproducibly causes sporadic intestinal and colonic tumors in the mouse, reflecting human etiology, incidence, frequency and lag with developmental age. Complex NWD1 reprogramming of stem cells and lineages was deconvolved by bulk and scRNAseq, scATACseq, functional genomics and imaging. NWD1 extensively, rapidly, and reversibly reprogrammed Lgr5hi stem cells, epigenetically down-regulating Ppargc1a expression, altering mitochondrial structure and function. This suppressed Lgr5hi stem cell functions and developmental maturation of Lgr5hi cell progeny as cells progressed through progenitor cell compartments, recapitulated by Ppargc1a genetic inactivation in Lgr5hi cells in vivo. Mobilized Bmi1+, Ascl2hi cells adapted lineages to the nutritional environment and elevated antigen processing and presentation pathways, especially in mature enterocytes, causing chronic, pro-tumorigenic low-level inflammation. There were multiple parallels between NWD1 remodeling of stem cells and lineages with pathogenic mechanisms in human inflammatory bowel disease, also pro-tumorigenic. Moreover, the shift to alternate stem cells reflects that the balance between Lg5 positive and negative stem cells in supporting human colon tumors is determined by environmental influences. Stem cell and lineage plasticity in response to nutrients supports historic concepts of homeostasis as a continual adaptation to environment, with the human mucosa likely in constant flux in response to changing nutrient exposures. Thus, although oncogenic mutations provide a competitive advantage to intestinal epithelial cells in clonal expansion, the competition is on a playing field dynamically sculpted by the nutritional environment, influencing which cells dominate in mucosal maintenance and tumorigenesis.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
All authors state there are no conflicts of interest
Data accession numbers: NCBI Gene Expression Omnibus (GEO) database: GSE186811; GSE188339; GSE188577; GSE188338.
Transparency: bulk and single cell RNAseq data sets are available from the public repositories; reagents will be made available to other investigators upon request to the corresponding author.
Synopsis: Mouse nutrient exposures reflecting those in humans dynamically remodel mouse stem cells and lineages, uniquely causing sporadic intestinal and colon tumors as in humans. Pathogenic mucosal alterations parallel aspects of human inflammatory bowel disease and plasticity of stem cell populations in human tumors.
text and figures revised