Abstract 1307: Pericytes promote colorectal cancer metastasis by remodeling perivascular matrix

Backgrounds: Hematogenous dissemination is a prevalent route of colorectal cancer (CRC) metastasis, whereas the underlying mechanism is unclear. Tumor pericytes (TPCs) are important components of tumor vessels, which are attached to the endothelial cells and embedded within the walls of capillaries. However, as the gatekeeper of vessels, the role of TPCs in hematogenous metastasis remains largely unknown. Here, we aimed to investigate the heterogeneity of TPCs and their effects on CRC metastasis. Methods: TPCs were first isolated from the primary CRC tissues using microdissection combined with pericyte medium-based approach. Then, TPCs derived from CRC liver-metastatic (CRCLM) and CRC non-metastatic (CRCNM) patients were analyzed by single-cell RNA sequencing (scRNA-seq). Clinical CRC specimens were collected to analyze the association between the molecular profiling of TPCs and CRC metastasis. The mechanisms by which TCF21 regulated perivascular matrix remodeling and integrin α5 modulated TCF21 DNA hypermethylation were investigated using RNA-sequencing, chromatin immunoprecipitation-sequencing and bisulfite-sequencing. Pericyte-conditional Tcf21-knockout mice were constructed to investigate the effects of TCF21 in TPCs on CRC metastasis. Masson staining, atomic force microscopy, second-harmonic generation and two-photon fluorescence microscopy were employed to observe perivascular extracellular matrix (ECM) remodeling. Pericyte TCF21-targeting peptide was designed by AlphaFold and its mechanisms were examined by microscale thermophoresis. Results: Thirteen TPC subpopulations were identified by scRNA-seq. A novel subpopulation of TCF21high TPCs was found to bed associated with liver metastasis in CRC patients. Genes highly-expressed in TCF21high TPCs were enriched in ECM and ECM remodeling, thus termed as matrix pericytes. TCF21 in TPCs increased perivascular ECM stiffness, collagen rearrangement and basement membrane degradation, establishing a perivascular metastatic microenvironment to instigate CRC liver metastasis. Mechanistic studies indicated that loss of integrin α5 inhibited the FAK/PI3K/AKT/DNMT1 axis to impair TCF21 DNA hypermethylation in TCF21high TPCs. Conditional deletion of Tcf21 in TPCs or pharmacological blocking the transcriptional activity of TCF21 in TPCs could mitigate perivascular ECM remodeling and CRC liver metastasis. Conclusions: This study first uncovers the heterogeneity of TPCs during CRC liver metastasis and reveals a novel mechanism that TPCs drive CRC liver metastasis through remodeling perivascular matrix, which provides a potential diagnostic marker and therapeutic target for CRC metastasis. Citation Format: Xiaobo Li, Jinghua Pan, Qun Miao, Xiaoyu Wu, Zhan Zhao, Yihai Cao, Minfeng Chen, Dongmei Zhang, Wencai Ye. Pericytes promote colorectal cancer metastasis by remodeling perivascular matrix [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1307.