Cytotoxic and epigenetic effects of berberine-loaded chitosan/pectin nanoparticles on AGS gastric cancer cells: Role of the miR-185-5p/KLF7 axis, DNMTs, and global DNA methylation.

Poor bioavailability, solubility, and absorption of berberine (Ber) limit its widespread application. Here, we formulated novel chitosan/pectin nanoparticles (NPs) loaded with Ber to address delivery problems and promote the anticancer properties of Ber in AGS gastric cancer cells. The ionic gelification method was used to synthesize NPs-Ber. Physicochemical characterization of NPs-Ber was performed using FE-SEM, DLS, PDI, ζ potential, and FTIR. The cytotoxic effects of NPs-Ber on AGS cells were evaluated using the MTT assay. Apoptosis and cell cycle arrest were examined by flow cytometry. The gene expression levels of miR-185-5p, KLF7, caspase-3, and DNMTs were determined using RT-qPCR. In addition, the 5-methylcytosine level in the genomic DNA was quantified using ELISA. FE-SEM images revealed a denser and more packed matrix for NPs-Ber, and FTIR analysis confirmed the formation of NPs-Ber. The size (550.39 nm), PDI (0.134), and ζ potential (-16.52 mV) confirmed the stability of the prepared NPs-Ber. NPs-Ber showed a continuous release pattern following the Korsmeyer-Peppas model such that 81.36 % of Ber was released from the formulation after 240 min. Compared to NPs and free Ber, NPs-Ber was found to possess higher anticancer activity in AGS cells. This result was indicated by the viability test and further clarified by augmented apoptosis and cell cycle arrest at the G0/G1 phase. The IC50 value of NP-Ber against AGS cells was significantly lower than those of free Ber and NPs. Interestingly, our results showed that NPs-Ber considerably changed the expression levels of miR-185-5p, KLF7, caspase-3, and DNMTs (DNMT1, 3A, and 3B) compared with unloaded NPs and free Ber. Additionally, 5-methylated cytosine (5-mC) levels in cells treated with NPs-Ber were significantly higher than those in cells treated with unloaded NPs or free Ber. In summary, the present study demonstrated that Ber encapsulation in NPs enhances its cytotoxic and epigenetic effects on AGS cells, suggesting the promising potential of NPs-Ber in GC therapy.