Wnt Activation Alters Cell Competition, Facilitating Cancer Formation

Living cells engage in fierce competition, adapting to their local environment; those unable to do so face elimination. This cellular competition is vital for identifying and eliminating mutant cancer cells by normal epithelial cells. Studies have reported that when activating mutants of Ras proteins are expressed in mammalian epithelial cells, they are pushed toward the lumen, excreted along with other bodily waste, and eliminated by competition. Epithelial cells containing Ras mutants have been reported to be removed in this manner in several organs, including the small intestine, stomach, pancreas, and lungs. This suggests that cell competition is an innate defense system orchestrated by epithelial cells to prevent the accumulation of incidentally produced cancerous cells and thereby suppress cancer formation.

While cancer typically arises through stepwise accumulation of mutations, the impact of this process on cell competition remains unclear. In a study recently published in Nature Communications study, led by Shunsuke Kon from Tokyo University of Science, researchers explored how stepwise gene mutations affect cell competition and contribute to cancer formation. Their study sheds light on the intricate relationship between gene mutations and cell competition.

The results unveiled that activated Wnt signals altered cell competition function. Specifically, Ras mutant epithelial cells, which would normally be eliminated, instead formed invasive tumors when Wnt signals were activated. Matrix metalloproteinase 21 (MMP21) overexpression, triggered by nuclear factor kappa B (NF-κB) signaling, was identified as a mechanism promoting the production of invasive cancer cells in early colorectal cancer. Blocking NF-κB signaling restored the elimination process, raising intriguing questions for future exploration.

The study demonstrates that cancer cells with sequential genetic mutations exploit altered cell competition, infiltrating tissues and producing high-grade cancer cells. Notably, Wnt activation disrupts cell competition, enabling transformed cells to escape primary epithelial sites. Although the study focused on mice with diffuse-type cancer, further research is needed to determine the pathway's relevance to other cancers.

The findings suggest therapeutic potential, particularly for researchers focused on Wnt signaling or cancer research. Dr. Kon emphasizes that understanding how cell competition constrains the order of mutations during tumor development could pave the way for novel cancer treatments, holding promise for the broader scientific community.