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BACKGROUND AND AIMS: Cancer-associated fibroblasts (CAFs) play an important role in colorectal cancer (CRC) progression and predict poor prognosis in CRC patients. However, the cellular origins of CAFs remain unknown, making it challenging to therapeutically target these cells. Here, we aimed to identify the origins and contribution of colorectal CAFs associated with poor prognosis. METHODS: To elucidate CAF origins, we used a colitis-associated CRC mouse model in 5 different fate-mapping mouse lines with BrdU dosing. RNA-sequencing of fluorescence-activated cell sorting (FACS)-purified CRC CAFs was performed to identify a potential therapeutic target in CAFs. To examine the prognostic significance of the stromal target, CRC patient RNA-sequencing data and tissue microarray were used. CRC organoids were injected into the colon of knockout mice to assess the mechanism by which the stromal gene contributes to colorectal tumorigenesis. RESULTS: Our lineage-tracing studies revealed that, in CRC, many ACTA2+ CAFs emerge through proliferation from intestinal pericryptal Leptin receptor (Lepr)+ cells. These Lepr-lineage CAFs, in turn, express melanoma cell adhesion molecule (MCAM), a CRC stroma-specific marker we identified using RNA-sequencing. High MCAM expression induced by TGF-β was inversely associated with patient survival in human CRC. In mice, stromal Mcam knockout attenuated orthotopically injected colorectal tumoroid growth and improved survival through decreased tumor-associated macrophage recruitment. Mechanistically, fibroblast MCAM interacted with interleukin-1 receptor 1 to augment nuclear factor-ĸB-IL34/CCL8 signaling that promotes macrophage chemotaxis. CONCLUSION: In colorectal carcinogenesis, pericryptal Lepr-lineage cells proliferate to generate MCAM+ CAFs that shape the tumor-promoting immune microenvironment. Preventing the expansion/differentiation of Lepr-lineage CAFs or inhibiting MCAM activity could be effective therapeutic approaches for CRC.

Original publication

DOI

10.1053/j.gastro.2021.11.037

Type

Journal article

Journal

Gastroenterology

Publication Date

06/12/2021

Keywords

CD146, alpha-smooth muscle actin (αSMA), colorectal cancer, tumor microenvironment