Colorectal cancer-derived small extracellular vesicles induce TGFβ1-mediated epithelial to mesenchymal transition of hepatocytes

Abstract

Background Metastatic disease is the major cause of cancer-related deaths. Increasing evidence shows that primary tumor cells can promote metastasis by preparing the local microenvironment of distant organs, inducing the formation of the so-called “pre-metastatic niche”. In recent years, several studies have highlighted that among the tumor-derived molecular components active in pre-metastatic niche formation, small extracellular vesicles (sEVs) play a crucial role. Regarding liver metastasis, the ability of tumor-derived sEVs to affect the activities of non-parenchymal cells such as Kupffer cells and hepatic stellate cells is well described, while the effects on hepatocytes, the most conspicuous and functionally relevant hepatic cellular component, remain unknown. Methods sEVs isolated from SW480 and SW620 CRC cells and from clinical samples of CRC patients and healthy subjects were used to treat human healthy hepatocytes (THLE-2 cells). RT-qPCR, Western blot and confocal microscopy were applied to investigate the effects of this treatment. Results Our study shows for the first time that TGFβ1-carrying CRC_sEVs impair the morphological and functional properties of healthy human hepatocytes by triggering their TGFβ1/SMAD-dependent EMT. These abilities of CRC_sEVs were further confirmed by evaluating the effects elicited on hepatocytes by sEVs isolated from plasma and biopsies from CRC patients. Conclusions Since it is known that EMT of hepatocytes leads to the formation of a fibrotic environment, a well-known driver of metastasis, these results suggest that CRC_sEV-educated hepatocytes could have an active and until now neglected role during liver metastasis formation.

Cells in the liver microenvironment regulate the process of liver metastasis

“…Small extracellular vesicles derived from colorectal cancer (CRC) cells directly target hepatocytes, trigger epithelial‐mesenchymal transition (EMT) and form a fibrotic microenvironment 13 . Yoong et al demonstrated that CRC metastatic cells induced the expression of Factor‐related Apoptosis (Fas) in hepatocytes, killing them by cytotoxic T lymphocytes (CTL) or tumor cells carrying Factor‐related Apoptosis ligand (FasL), and promoting local invasion of cancer cells 14 .…”

“…In the process of liver metastasis of CRC cells, cells in the liver microenvironment are mobilized to play different roles. Pucci's et al study shows that CRC extracellular vesicles carrying TGF‐β1 damage hepatocytes by triggering TGFβ1/SMAD‐dependent EMT 13 . Wei et al demonstrated that TAMs enhanced CRC migration and invasion by regulating JAK2/STAT3/miR‐506‐3p/FoxQ1 axis to induce EMT 59 .…”

The multifaceted role of extracellular vesicles (EVs) in colorectal cancer: metastasis, immune suppression, therapy resistance, and autophagy crosstalk

“…Abundant signaling pathways (including Wnt, TGF-β, p53, mTOR, MAPK, and JAK-STAT) and multiple transcriptional factors (such as TWIST, SNAIL, Slug, FOX, and zinc-finger E-box binding (ZEB)) have been described to modulate EMT. EVs derived from diverse cells in CRC microenvironment have been implicated in initiating metastasis and driving EMT [ 34 – 36 ].…”