Loss of exosomal micro-RNA-200b-3p from hypoxia cancer-associated fibroblasts reduces sensitivity to 5-flourouracil in colorectal cancer through targeting high-mobility group box 3

Abstract

Hypoxia-mediated tumor progression is a major problem in colorectal cancer (CRC). MicroRNA (miR)-200b-3p can attenuate tumorigenesis in CRC, while exosomal miRNAs derived from cancer-associated fibroblasts (CAFs) can promote cancer progression. Nevertheless, the function of exosomal miR-200b-3p derived from CAFs in CRC remains unclear. In this study, CAFs and normal fibroblasts (NFs) were isolated from CRC and adjacent normal tissues. Next, exosomes were isolated from the supernatants of CAFs cultured under normoxia and hypoxia. Cell viability was tested using the cell counting kit-8 assay, and flow cytometry was used to assess cell apoptosis. Cell invasion and migration were evaluated using the transwell assay. Dual-luciferase was used to investigate the relationship between miR-200b-3p and high-mobility group box 3 (HMBG3). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to determine the miR-200b-3p and HMBG3 level. Our results found that the miR-200b-3p level was sharply reduced in CRC tissues compared to adjacent normal tissues. Additionally, the miR-200b-3p level was reduced in exosomes derived from hypoxic CAFs compared to exosomes derived from CAFs under normoxia. Exosomes derived from hypoxic CAFs weakened the sensitivity of CRC cells to 5-fluorouracil (5-FU) compared to hypoxic CAFs-derived exosomes. However, hypoxic CAFs-derived exosomes with upregulated miR-200b-3p increased the sensitivity of CRC cells to 5-fluorouracil (5-FU) compared to hypoxic CAFs-derived exosomes. In addition, HMBG3 was identified as the downstream target of miR-200b-3p in CRC cells, and its overexpression partially reversed the anti-tumor effect of the miR-200b-3p agomir on CRC via the mediation of the β-catenin/c-Myc axis. Furthermore, compared to exosomes derived from normoxia CAFs, exosomes derived from hypoxic CAFs weakened the therapeutic effects of 5-FU on CRC in vivo via the upregulation of HMGB3 levels. Collectively, the loss of exosomal miR-200b-3p in hypoxia CAFs reduced the sensitivity to 5-FU in CRC by targeting HMGB3. Thus, our research outlines a novel method for the treatment of CRC.

The hidden messengers: cancer associated fibroblasts—derived exosomal miRNAs as key regulators of cancer malignancy

“…CAF-derived exosomal miRNA also plays a certain role in enhancing drug sensitivity. For example, miR-200b-3p was upregulated in exosomes derived from hypoxic CAFs, improving the sensitivity of CRC to 5-fluorouracil by targeting high mobility group protein 3 ( Yuan et al, 2022 ). In addition, miR-195 in CAF-derived exosomes improved the survival rate in rat models of intrahepatic cholangiocarcinoma ( Li et al, 2017 ).…”

Crosstalk between colorectal cancer cells and cancer-associated fibroblasts in the tumor microenvironment mediated by exosomal noncoding RNAs

“…The expression levels of miR-200b-3p were significantly lower in CRC tissues than in normal control tissues, and miR-200b-3p expression levels were also lower in hypoxic CAFs than in normoxic CAFs. Compared with the exosomes of normoxic CAFs, the exosomes of hypoxic CAFs could target HMGB3 and bcatenin/c-Myc regulatory axis by secreting miR-200b-3p and thus promote the therapeutic effect of 5-FU on CRC in vivo ( 113 ).…”