Fig. 7

HDAC9 knockdown increases cell apoptosis and inhibits cell viability of NP cells in vitro. A Identification of isolated NP cells by collagen II using fluorescence staining. Scale bar, 100 μm. B, C NP cells were infected with lentivirus-mediated shHDAC9 (Lt.shHDAC9-1, 2, and 3) for 72 h. The relative mRNA level and protein level of HDAC9 in Lt.shHDAC9-infected NP cells were detected by RT–qPCR and western blot. D Cell viability of NP cells was measured by CCK-8 assay. E Apoptotic cells were stained with annexin V/propidium iodide and quantified by flow cytometry. The relative mRNA level of p21 (F), cyclin D1 (G), and PUMA (H). I, J The protein level of p21, cyclin D1, p53, and PUMA. K HDAC9^KO NP cells were infected with adenovirus containing cDNA of HDAC9 (Ad.HDAC9) for 72 h and the protein level of HDAC9 was detected. L Cell viability of NP cells was measured by CCK-8 assay. M Apoptotic cells were stained with annexin V/propidium iodide and quantified by flow cytometry. Data are represented as mean ± SD (n = 3). A p-value of less than 0.05 was considered significant using one-way ANOVA and Tukey’s multiple comparison test