Unraveling the Life Cycle of Metastatic Cells from Invasion to Outgrowth.

Colorectal cancer (CRC) is the second leading cause of cancer-related mortality worldwide, accounting fornearly 10% of cancer-related deaths. The majority of CRC-related deaths result from metastaticdissemination, with the liver and lung being the most frequent distant sites of metastasis. Effective therapiesto prevent metastatic CRC progression are lacking. This gap stems from our limited understanding of thecancer-intrinsic and tumor microenvironmental factors that drive advancement through each intermediatestep of the metastatic cascade.Here, we will use systems approaches to unravel the life cycle of metastatic cells, focusing on cancer cellplasticity and interactions with host tissues. First, we will use in vivo CRISPR screening to identify driversof invasion, dissemination, seeding, and outgrowth. This approach will be complemented by single-cellmulti-omics analyses to uncover the regulatory networks governing these processes. Next, we will explorethe dynamics of the liver pre-metastatic niche using single-cell RNA sequencing, proximity labeling, andimmunofluorescence to dissect its metastasis-promoting cellular networks and gradual reversal after primarytumor ablation. Finally, we will identify host factors that regulate metastatic extravasation and vessel co-option by functionally investigating the role of liver endothelial cells throughout metastatic progression.This will be achieved through a combination of in vivo interaction screening, in vitro models, andcomparison to spatial transcriptomic datasets from patient samples.By integrating these complementary approaches, our study aims to provide a comprehensive understandingof the key drivers and modulators of metastatic CRC. These insights could pave the way for the developmentof novel therapeutic strategies aimed at preventing or limiting metastatic disease progression in CRCpatients.