RESUMO
Objective Based on quantitative proteomics analysis and molecular biology experimental verification, the regulatory mechanism of ginsenoside Rd on histone H3 acetylation levels was elucidated. Methods The effects of ginsenoside Rd on the dynamic changes of proteome of HEK293T cells were detected by.stable isotope labeling with amino acid (SILAC) technique and LC-MS/MS; Quantitative proteomics database analysis was used to monitor the changes in histone acetyltransferase HATs and histone deacetylase HDACs expression levels. Western blotting and qRT-PCR were used to verify the changes of related protein expression and transcriptional level. Gene knockdown experiments were performed using siRNAs to determine the role of ginsenoside Rd in regulating the level of acetyl modifications at histone H3K9 and K18 sites. Results The histone H3K9ac, H3K18ac expression levels in HEK293T cells decreased after ginsenoside Rd treatment, but the P300 catalytic modification of these two sites did not change significantly; At the same time, ginsenoside Rd up-regulated the transcription and expression of HDAC2, and siHDAC2 treatment reversed the down-regulation effects of ginsenoside Rd on H3K9ac and H3K18ac in HEK293T cells. Conclusion Ginsenoside Rd down-regulates the acetylation level of lysine at histone H3K9 and K18 sites by up-regulating HDAC2, thereby affecting transcriptional activation of downstream genes.
RESUMO
BACKGROUND: SIRT7 is one of the histone deacetylases and is NAD-dependent. It forms a complex with ETS-like transcription factor 4 (ELK4), which deacetylates H3K18ac and works as a transcriptional suppressor. Overexpression of SIRT7 and deacetylation of H3K18ac have been shown to be associated with aggressive clinical behavior in some cancers, including hepatocellular carcinoma (HCC). The present study investigated the immunohistochemical expression of SIRT7, H3K18ac, and ELK4 in hepatocellular carcinoma. METHODS: A total of 278 HCC patients were enrolled in this study. Tissue microarray blocks were made from existing paraffin-embedded blocks. Immunohistochemical expressions of SIRT7, H3K18ac and ELK4 were scored and analyzed. RESULTS: High SIRT7 (p = .034), high H3K18ac (p = .001), and low ELK4 (p = .021) groups were associated with poor outcomes. Age < 65 years (p = .028), tumor size ≥ 5 cm (p = .001), presence of vascular emboli (p = .003), involvement of surgical margin (p = .001), and high American Joint Committee on Cancer stage (III&V) (p < .001) were correlated with worse prognoses. In multivariate analysis, H3K18ac (p = .001) and ELK4 (p = .015) were the significant independent prognostic factors. CONCLUSIONS: High SIRT7 expression with poor overall survival implies that deacetylation of H3K18ac contributes to progression of HCC. High H3K18ac expression with poor prognosis is predicted due to a compensation mechanism. In addition, high ELK4 expression with good prognosis suggests another role of ELK4 as a tumor suppressor beyond SIRT7's helper. In conclusion, we could assume that the H3K18ac deacetylation pathway is influenced by many other factors.