Colorectal cancer cells-derived exosomal miR-188-3p promotes liver metastasis by creating a pre-metastatic niche via activation of hepatic stellate cells.

BACKGROUND/AIM: Metastasis is the leading cause of mortality for colorectal cancer (CRC). Cancer-derived exosomes are widely recognized as the primary catalysts behind the development of pre-metastasis niche (PMN) in distal sites. However, the exact mechanism behind this process in CRC remains elusive. This study aimed to investigate the function and mechanisms underlying the role of exosomal miR-188-3p in activating hepatic stellate cells (HSCs) to develop the PMN and promote liver metastasis.

METHODS

We extracted exosomes from CRC cells using ultracentrifugation. Exosomes were identified using transmission electron microscopy, nanoparticle tracking analysis, and Western blot. Exosome uptake was assessed using fluorescence tracing, exosome PKH67 staining, and real-time quantitative PCR. The effects of CRC cell-derived exosomes on HSCs migration were evaluated using Transwell migration and wound healing assays. Key differentially expressed miRNAs were screened from the GEO database, and bioinformatics prediction along with dual-luciferase reporter assays were used to identify downstream target genes of miR-188-3p. Downstream related proteins of the target genes were detected by Western blot. In vivo, the distribution of exosomes and activation of HSCs in the liver were explored by tail vein injection of exosomes into nude mice. Further, the impact of exosomal miR-188-3p on liver metastasis was investigated using a spleen injection liver metastasis model. Finally, the expression levels of miR-188-3p in exosomes from CRC patient plasma were determined by real-time quantitative PCR, and the relationship between the expression of miR-188-3p in plasma exosomes and CRC prognosis was analyzed.

RESULTS

The expression level of miR-188-3p within plasma exosomes demonstrated a statistically significant increase in CRC with liver metastasis compared to those without liver metastases. We also demonstrated the transferability of miR-188-3p from CRC cells to HSCs cells via the exosomes. Exosomal miR-188-3p plays a pivotal role in orchestrating the establishment of PMN through targeting PHLPP2 to activate HSCs before tumor metastasis. Exosomal miR-188-3p was found to actively foster in vivo metastasis of CRC. Additionally, plasma exosomal miR-188-3p potentially serves as a viable blood-based biomarker for CRLM.

CONCLUSION

Exosomal miR-188-3p derived from CRC cells can promote liver metastasis by activating HSCs to form a PMN through targeting PHLPP2 to activate the AKT/mTOR pathway. These results offer a new perspective on the mechanisms driving CRLM.