VIPR1 promoter methylation promotes transcription factor AP-2α binding to inhibit VIPR1 expression and promote hepatocellular carcinoma cell growth in vitro / 南方医科大学学报

OBJECTIVE@#To explore the transcriptional regulation mechanism and biological function of low expression of vasoactive intestinal peptide receptor 1 (VIPR1) in hepatocellular carcinoma (HCC).@*METHODS@#We constructed plasmids carrying wild-type VIPR1 promoter or two mutant VIPR1 promoter sequences for transfection of the HCC cell lines Hep3B and Huh7, and examined the effect of AP-2α expression on VIPR1 promoter activity using dual-luciferase reporter assay. Pyrosequencing was performed to detect the changes in VIPR1 promoter methylation level in HCC cells treated with a DNA methyltransferase inhibitor (DAC). Chromatin immunoprecipitation was used to evaluate the binding ability of AP-2α to VIPR1 promoter. Western blotting was used to assess the effect of AP-2α knockdown on VIPR1 expression and examine the differential expression of VIPR1 in the two cell lines. The effects of VIPR1 overexpression and knockdown on the proliferation, cell cycle and apoptosis of HCC cells were analyzed using CCK8 assay and flow cytometry. We also observed the growth of HCC xenograft with lentivirus-mediated over-expression of VIPR1 in nude mice.@*RESULTS@#Compared with the wild-type VIPR1 promoter group, co-transfection with the vector carrying two promoter mutations and the AP-2α-over-expressing plasmid obviously restored the luciferase activity in HCC cells (P < 0.05). DAC treatment of the cells significantly decreased the methylation level of VIPR1 promoter and inhibited the binding of AP-2α to VIPR1 promoter (P < 0.01). The HCC cells with AP-2α knockdown showed increased VIPR1 expression, which was lower in Huh7 cells than in Hep3B cells. VIPR1 overexpression in HCC cells caused significant cell cycle arrest in G2/M phase (P < 0.01), promoted cell apoptosis (P < 0.001), and inhibited cell proliferation (P < 0.001), while VIPR1 knockdown produced the opposite effects. In the tumor-bearing nude mice, VIPR1 overexpression in the HCC cells significantly suppressed the increase of tumor volume (P < 0.001) and weight (P < 0.05).@*CONCLUSION@#VIPR1 promoter methylation in HCC promotes the binding of AP-2α and inhibits VIPR1 expression, while VIPR1 overexpression causes cell cycle arrest, promotes cell apoptosis, and inhibits cell proliferation and tumor growth.

Research progress on effect of AP2/ERF transcription factors in regulating secondary metabolite biosynthesis / 中国中药杂志

AP2/ERF transcription factor is a kind of transcription factors widely existing in plants, and contains at least a conserved AP2/ERF domain composed of about 60-70 amino acids. AP2/ERF transcription factors are widely involved in a variety of physiological processes in plants, including plant development, fruit ripening, flower development and other plant development processes, as well as such stress response processes as damage, pathogen defense, high-salt condition and drought. In recent years, secondary metabolic engineering that takes transcription factors as genetic manipulation targets has developed rapidly in improving the content of active ingredients and the quality of medicinal plants. This paper reviews the recent progress in the regulation of secondary metabolites biosynthesis with AP2/ERF transcription factors, and provides theoretical basis for the exploration of efficient regulatory targets, the regulation of secondary metabolites in medicinal plants, the targeted improvement of the content of active ingredients in traditional Chinese medicine, and the sustainable supply of high-quality traditional Chinese medicines.