Hepatology. 2021 Jun 10.
Hao Sun,
Qingtao Meng,
Chengyu Shi,
Hongbao Yang,
Xiaobo Li,
Shenshen Wu,
Giuseppe Familiari,
Michela Relucenti,
Michael Aschner,
Xuehao Wang,
Rui Chen.
BACKGROUND & AIMS: Liver metastasis is a frequent occurrences in patients with colorectal cancer (CRC), 15%-25% of CRC patients have liver metastases at the time of initial diagnosis (1). Specifically, some regional-stage patients with mild symptoms (stage Ⅰ or II) will also advance to liver metastases rapidly, even CRC lesion in situ is resected in time. Nevertheless, the precise mechanism of liver metastasis is still unclear.
APPROACH & RESULTS: Fresh tumor tissues from CRC patients, adjacent noncancerous tissues (ANT) and colorectal adenoma tissues (ADE) were subjected to microarray analysis to identify differentially expressed miRNA. Exosomes from human serum and cell culture medium were separated, quantitated and verified by transmission electronic microscopy and Zetasizer Nano. Luciferase reporter assay, real-time qPCR, western blot, immunoprecipitation, chromatin and re-chromatin immunoprecipitation, migration and invasion assay, PDX mice model, flow cytometry, immunohistochemistry and immunofluorescence staining were employed to explore the regulation among CRC liver metastases, immunosuppression and cell adhesion. In this study, we demonstrated that the hypoxic microenvironment in primary CRC lesions boosted exosome release, selectively initiated a favorable pre-metastatic niche formation in the hepar, but not in other organs. Mechanistically, Kupffer cells (KCs) can phagocytose exosomes contained highly expressed miR-135a-5p from blood circulation into the liver. The exosomal miR-135a-5p initiated LATS2-YAP-MMP7 axis to promote the occurrences of CRC liver metastasis, and CD30-TRAF2-p65-mediated immunosuppression signaling also contributed to this process.
CONCLUSIONS: Hypoxia-induced exosomal miR-135a-5p correlates with the development, clinical severity and prognosis of CRC liver metastases through the pre-metastatic niche, and our findings revealed that miR-135a-5p might be a promising target in halting CRC liver metastases.
Keywords: Colorectal Cancer; Exosome; Liver Metastasis; Pre-Metastatic Niche