Abstract
Objective:
To explore the mechanisms of the TGF-β1/Smad and NF-κB pathways in the effect of berberine (BBR) on colon cancer epithelial-mesenchymal transition (EMT) and their regulatory relationships with microRNAs (miRNAs).
Methods:
TGF-β1 was used to induce EMT in normal colon epithelial HCoEpiC cells and colon cancer HT29 cells in vitro. After BBR intervention, the expression of EMT-related markers and the major molecules involved in the TGF-β1/Smad and NF-κB pathways were detected via western blotting. Cell migration was detected via wound healing assays. SMAD2 and NF-κB p65 were overexpressed and transfected into cells, and the inhibitors SB431542 and BAY 11-7082 were added to block the TGF-β1/Smad and NF-κB pathways, respectively. The mRNA expression levels of related microRNA genes were detected by using RT‒PCR.
Results:
Treatment with 10 ng/ml TGF-β1 for 72 h significantly induced EMT in HCoEpiC and HT29 cells, which was repressed by BBR. BBR significantly inhibited the TGF-β1-induced migration of HCoEpiC and HT29 cells and the TGF-β1-promoted expression of p-Smad2/3, NF-κB p65, and p-IκBα. Compared to those in the group treated with TGF-β1, the expression of NF-κB p65 and p-Smad2 in the group treated with NF-κB pathway inhibitor BAY 11-7082 was decreased (P < 0.05), and TGF-β1 signalling inhibitor SB431542 significantly reduced the expression of NF-κB p65 (P < 0.05). Overexpression of NF-κB p65 and SMAD2 in HT29 cells decreased the expression of E-cadherin and caused a relative increase in N-cadherin. BBR mediated the expression profile of microRNAs in TGF-β1-induced HCoEpiC cells, but this pattern differed from that in HT29 cells. SB431542 and BAY 11-7082 significantly reduced the mRNA level of miR-1269a in HCoEpiC and HT29 cells (P < 0.05). Overexpressed NF-κB p65 and SMAD2 increased the mRNA level of miR-1269a in both cell lines; however, this increase was significantly lower than that in the TGF-β1 treatment group (P < 0.05).
Conclusion:
BBR can significantly inhibit TGF-β1-induced EMT in normal and cancerous colon epithelial cells through the inhibition of the TGF-β1/Smad and NF-κB p65 pathways. TGF-β1/Smads can promote the NF-κB p65 pathway, which is a common target of miR-1269a, and can partially regulate the expression of miR-1269a.
Keywords:
Berberine; Colon cancer; Epithelial–mesenchymal transition; Noncoding RNA; Transforming growth factor beta 1.