Mechanistically, miR-21-5p and miR-155-5p were transferred to colorectal cancer cells by MDE and bound to the BRG1 coding sequence, downregulating expression of BRG1, which has been identified as a key factor promoting the colorectal cancer metastasis, yet is downregulated in metastatic colorectal cancer cells.
Overall, our data show that EGCG may be act as a novel chemo-sensitizer, and the GRP78/NF-κB/miR-155-5p/MDR1 pathway plays a vital role in EGCG enhancing the sensitivity of colorectal cancer to 5-FU.
IMPLICATIONS: This study supports a key role of miR-155-5p in modulating WNT/β-CATENIN signaling in colorectal cancer and unravels a new mechanism for AXIN1 regulation which represents a potential therapeutic target in specific tumor subtypes.
Rescue experiment confirmed that miR-204-5p is a functional target mediating the TAM-induced colorectal cancer chemoresistance. miR-155-5p, a key miRNA regulating C/EBPβ, was frequently downregulated in TAMs, resulting in increased C/EBPβ expression.
These observations indicate that miR-222 and miR-155 could induce radiation resistance in colorectal cancer by targeting PTEN and FOXO3a genes, respectively.
In particular, the dysregulation of miR-155 has been strongly implicated in Helicobacter pylori-related gastric disease, inflammatory bowel disease, and colorectal cancer in addition to being involved in molecular changes of important targets and signaling pathways.
MiR-34a (2.2-fold), miR-155 (2.3-fold) and miR-200c (3.1-fold) were all expressed at higher levels in colorectal cancer (P = 0.001, 0.005 and 0.001, respectively).