# Functional role of cancer stem cell like exosomes on survival and drug resistance behaviors of colorectal cancer cells

## TL;DR

This study shows that exosomes from colorectal cancer stem cells increase drug resistance and survival of cancer cells.

## Contribution

The novel contribution is identifying how cancer stem cell exosomes enhance drug resistance in colorectal cancer cells.

## Key findings

- Cancer stem cell exosomes significantly increase drug resistance gene expression in treated cells.
- Exosome-treated cells show reduced viability when combined with 5-fluorouracil compared to drug alone.
- Colorectal cancer stem cells exhibit higher stemness gene expression and marker levels than parental cells.

## Abstract

This study aimed to evaluate the potential impact of colorectal cancer stem cell exosomes (CRC CSCs-enriched exosomes/CSCs-EXOs) on drug resistance and cell proliferation of CRC tumor cells.

CSCs were enriched from HT-29 cells and characterized by sequential sphere formation, real-time PCR analysis of key stemness genes, and CRC-CSCs markers. The gene expression related to ABC transporters was analyzed in HT-29, HT-29 CSCs, and Caco-2 cells. CSCs-EXOs and parental-EXOs were isolated and characterized from HT-29 cells. The gene expression related to ABC transporters was investigated in Caco-2 cells treated with CSCs-EXOs and parental-EXOs of HT-29 cells by real-time PCR. The survival rate of exosome-treated Caco-2 cells was also studied in the presence of 5-fluorouracil (5-FU) at the IC50 concentration using MTT assay.

Colonospheres were found to have the ability to form serial spheres, along with the upregulatation of the key stemness genes (p-value ≤ 0.05). The expression of CRC-CSCs markers significantly increased relative to their parental counterparts (p-value ≤ 0.05). Treatment of Caco2 cells with CSCs-EXOs and their parental-EXOs revealed a substantial elevation in expression of drug resistance genes relative to those treated with their parental-EXOs (p-value ≤ 0.0001). The combination treatment of cells with exosomes and 5-FU at the IC50 concentration led to a more pronounced decrease in cell viability in all groups compared to applying 5-FU at the same concentration.

Our findings underscore the significance of targeting the CSCs-exosome axis as a prospective therapeutic strategy to overcome drug resistance. Upcoming studies ought to concentrate on exploring the molecular machinery of CSCs and tumor cells plasticity through the exosome-mediated functions.

The online version contains supplementary material available at 10.1007/s12672-025-04295-0.