Multi-omics analysis of spatially distinct stromal cells reveals tumor-induced O-glycosylation of the CDK4-pRB axis in fibroblasts at the invasive tumor edge

The invasive leading edge represents a potential gateway for tumor metastasis. The role of fibroblasts from the tumor edge in promoting cancer invasion and metastasis has not been comprehensively elucidated. We hypothesize that crosstalk between tumor and stromal cells within the tumor microenvironment (TME) results in activation of key biological pathways depending on their position in the tumor (edge vs core). Here we highlight phenotypic differences between tumor-adjacent-fibroblasts (TAF) from the invasive edge and tumor core fibroblasts (TCF) from the tumor core, established from human lung adenocarcinomas. A multi-omics approach that includes genomics, proteomics, and O-glycoproteomics was used to characterize crosstalk between TAFs and cancer cells. These analyses showed that O-glycosylation, an essential post-translational modification resulting from sugar metabolism, alters key biological pathways including the cyclin-dependent kinase 4 and phosphorylated retinoblastoma protein (CDK4-pRB) axis in the stroma and indirectly modulates pro-invasive features of cancer cells. In summary, the O-glycoproteome represents a new consideration for important biological processes involved in tumor-stroma crosstalk and a potential avenue to improve the anti-cancer efficacy of CDK4 inhibitors.