Dataset Information

Extracellular vesicles-derived microRNA-222 promotes immune escape via interacting with ATF3 to regulate AKT1 transcription in colorectal cancer.

ABSTRACT:

Background

Immunotherapy has been recently established as a new direction for the treatment of colorectal cancer (CRC), a gastrointestinal cancer. In this investigation, we aimed to expound how the posttranscriptional regulation modulated by microRNA-222 (miR-222) from mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) affected the AKT pathway and the immune escape in CRC.

Methods

CRC cell malignant phenotype, including proliferation, migration, invasion, and apoptosis, was firstly detected after co-culture with MSC-EVs. miRNAs with differential changes in CRC cells before and after EVs treatment were filtered by microarray analysis. miR-222 was then downregulated to examine its role in CRC cells in response to EVs. Cells were implanted in mice to induce xenograft tumors, and infiltrating T cells was assessed by immunohistochemistry. The mRNA microarray was used to screen target genes, followed by rescue experiments. ChIP and western blot were conducted to validate the downstream biomolecule of ATF3.

Results

After treatment of CRC cells with MSC-EVs, the expression of miR-222 was upregulated, and cell activity was increased. Inhibition of miR-222 decreased CRC malignant aggressiveness in vitro and reduced tumorigenesis and immune escape in vivo. miR-222 targeted and bound to ATF3. Downregulation of ATF3 enhanced CRC cell malignant aggressiveness, tumorigenic capacity and immune escape. Mechanistically, ATF3 inhibited AKT1 transcription and mediated the AKT pathway.

Conclusion

MSC-EVs carry miR-222 to promote CRC cell malignant aggressiveness and immune escape. miR-222 targets and binds to ATF3, which inhibits AKT1 transcriptional activity and thereby mediates the AKT pathway.

SUBMITTER: Li S

PROVIDER: S-EPMC8017736 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Most cancer-related deaths are caused by distant metastases, which are tumour cells that have escaped from a primary tumour and passed into the bloodstream to colonize a new organ. In this context, communication between tumour and stromal cells is essential. Indeed, tumor cells interact with cells in the tumor microenvironment and are able to modify them to their advantage. Both extracellular vesicles (EVs) and exosomes are heterogeneous populations of small vesicles present in the tumor microenvironment and in body fluids that have recently emerged as powerful mediators involved in this communication and their transport in fluids. Tumor cells release large quantities of exosomes containing tumor markers, which can then spread to distant locations. The exosomes are of endosomal origin. They are composed of proteins, lipids, RNA and DNA, and they circulate in the bloodstream. They can be internalized by specific distant cells and thus deliver a functional message. It has recently been shown that tumor exosomes containing pro-metastatic factors form pre-metastatic niches, before the tumor cells actually arrive, while determining the metastatic organotropism of tumors. These properties are now opening up new avenues of research in tumor biomarkers. In recent years, several studies have highlighted different markers contained specifically in exosomes derived from cancer cells. Consequently, exosomes are considered as potential reservoirs of tumor biomarkers that could be clinically useful for the non-invasive diagnosis of cancer, with the advantage of being performed by liquid biopsy. The study of microRNA (miRNA) is of particular interest. Indeed, miRNAs are small non-coding RNAs (between 21 and 25 nucleotides) involved in the regulation of gene expression and which are frequently deregulated in cancer. Several studies underline that the variation of free miRNAs in the blood is correlated with the progression of the disease, particularly in colon cancer. However, the stability of free miRNAs is controversial. Therefore, exosomes represent a very advantageous means of transporting miRNAs in the blood, as they are able to protect miRNAs from degradation by RNAase. The hypothesis of the project is that circulating exosomes derived from tumours contain markers including specific miRNAs that could be used as biomarkers of early prognosis (survival and progression), easily measured in blood samples from patients with colon cancer. But other molecules contained in exosomes could also be of interest.