Methyl fingerprinting of the nucleosome reveals the molecular mechanism of high-mobility group nucleosomal-2 (HMGN2) association

Paeonol-mediated apoptosis of hepatocellular carcinoma cells by NF-κB pathway

The aim of the study was to investigate the effect of paeonol on the apoptosis of hepatocellular carcinoma cells and to explore the possible mechanism of its effect. During the experiment, the human hepatoma (Huh7) cell line was cultured and treated with different concentrations of paeonol. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect the effects of paeonol at different concentrations on the proliferation of Huh7 cells after 24 h, and the optimal concentration of paeonol was selected for follow-up experiments. Huh7 cells were divided into the blank control group (C group), parthenolide [(an inhibitor of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB)] group (CE group), paeonol group (PO group), and paeonol + tumor necrosis factor-α (TNF-α) (an activator of NF-κB) group (PN group). The effect of paeonol on the apoptosis of Huh7 cells was detected via flow cytometry and Hoechst staining, respectively. The expression levels of NF-κB and protein apoptosis inhibitor-5 (p-API-5) were detected by semi-quantitative polymerase chain reaction (PCR) and western blot analysis, respectively, and the activity of NF-κB in cells was measured by NF-κB p65/50. After determination of the effects of paeonol at different concentrations on Huh7 cells by MTT assay, it was found that paeonol at the concentration of 200–800 µM could inhibit the proliferation of Huh7 cells (P<0.01), with 500 µM phenol being selected as the treatment concentration for follow-up experiments. Results of flow cytometry and Hoechst staining showed that the apoptotic levels of Huh7 cells in the PO and CE groups were significantly increased compared with that in the C group, and that in the PO group was higher than that in the PN group. The differences were statistically significant (P<0.01). Results of semi-quantitative PCR and western blot analysis revealed that the expression levels of NF-κB and p-API-5 in the PO and CE groups were significantly lower than those in the C group, and those in the PO group were lower than those in the PN group. The differences were statistically significant (P<0.01). The expression level of NF-κB p65/50 in the PO group was significantly lower than that in the C group (P<0.01). The results suggest that paeonol can significantly increase the apoptosis rate of Huh7 cells, and the possible mechanism of inducing apoptosis is related to the downregulation of NF-κB and p-API-5 and inhibition of the NF-κB signaling pathway.

Effect of HMGN2 on proliferation and apoptosis of MCF-7 breast cancer cells

We investigated the effect of high mobility group protein N2 (HMGN2) on the proliferation and apoptosis of the human MCF-7 breast cancer cell line, and its effect on tumor growth in a subcutaneous heterotopic transplantation tumor model of breast cancer. The cell viability assay was used to verify the effect of the recombinant human HMGN2 on MCF-7 cell proliferation. The Transwell chamber assay was used to verify the effect of HMGN2 on MCF-7 cell migration. Flow cytometry and Hoechst staining were used to detect the effect of HMGN2 on MCF-7 cell apoptosis. MCF-7 was injected to establish a subcutaneous heterotopic transplantation tumor model of breast cancer in nude mice. The size, weight and volume of tumor in each group were compared after the administration of different concentrations of HMGN2 solution around the tumor tissue at day 1, 3, 5 and 7. The tumor tissue was removed and cut into sections, and the apoptotic cells in tumors of nude mice were detected by a TUNEL kit. The CCK-8 assay showed that HMGN2 at different concentrations inhibited the proliferation of the MCF-7 breast cancer cells, and the proliferation of MCF-7 cells were significantly inhibited when the concentration of HMGN2 reached 3 µg/ml (P<0.01). The Transwell chamber assay showed that 3 µg/ml of HMGN2 significantly decreased the migration capacity of MCF-7 cells (P<0.01). Flow cytometry and Hoechst staining showed that 3 µg/ml of HMGN2 significantly increased apoptosis of MCF-7 cells (P<0.01). After the nude mouse model of breast cancer was established, HMGN2 at different concentrations was injected around the tumor tissue at day 1, 3, 5 and 7. We demonstrated that the growth of breast cancer was significantly inhibited when the concentration of HMGN2 reached 15 µg/ml. TUNEL staining showed that the number of apoptotic cells in the 15 µg/ml dose group was significantly higher than that in the control group (P<0.01). Therefore, in vitro and in vivo experiments proved that recombinant human HMGN2 could significantly inhibit the proliferation and migration of breast cancer cells, which increased the apoptosis of breast cancer cells and exerted anti-breast cancer effects, which enriched our understanding of the biological roles of HMGN2.