ACT001 reduced the expression of programmed cell death protein ligand 1 in glioblastoma cells by inhibiting P65 phosphorylation

Abstract

Objective To investigate the anti⁃tumoral effect of ACT001, a novel antitumor compound, on the nuclear factor⁃κB (NF⁃κB) pathway and programmed cell death protein ligand 1 (PDL1) expression in U87 glioblastoma cell line. Methods We analyzed the correlation between the expression of P65 and PDL1, pathological grade, and prognosis by introducing The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. CCK⁃8 was used to observe the effect of ACT001 on the proliferation of U87 cells, and calculate the median inhibition concentration (IC50). Immunofluorescence staining was used to detect the effect of ACT001 on nuclear translocation of the transcription factor P65. U87 cells were transfected with small interference RNA (siRNA), and P65 knockdown efficiency was determined by quantitative real⁃time polymerase chain reaction (qRT⁃PCR). The relative expression of P65, phospho⁃P65 (p⁃P65) and PDL1 in different transfected groups and drug treatment groups were determined by Western blotting. Results 1) Bioinformatics analysis showed that gliomas with higher pathological grade hourbored higher P65 and PDL1 expression (P＜0.05, for all). Moreover, patients with high expression of P65 and PDL1 mRNA predicted poor prognosis (P＜0.05, for all). 2) CCK⁃8 assay showed that treatment with different concentrations of ACT001 (5, 10, 20, 40, 80, 160 and 320 μmol/L), the inhibition rates of U87 cells were (9.01±4.75)%, (17.03±2.91)%, (28.50±4.85)%, (45.50±5.15)%, (67.67±8.46)% , (83.02±5.79)% and (94.33±1.59)% , respectively, and the IC50 was about 42.98 μmol/L. 3) Immunofluorescence staining showed that ACT001 inhibited nuclear translocation of P65. 4) qRT⁃PCR showed that the P65 mRNA expression of U87 cells in different siRNA transfected groups was statistically significant (F=164.200, P=0.000), and the mRNA expression of P65 in si⁃P65⁃1 group (t=13.290, P=0.000) and si⁃P65⁃2 group (t=12.730, P=0.000) was lower than that of si⁃NC group. 5) Western blotting showed that the relative expression of P65 (F=681.300, P=0.000), p⁃P65 (F=128.800, P=0.000) and PDL1 (F=20.470, P=0.002) in U87 cells of different siRNA transfection groups were statistically significant different. Among them, P65 (t=59.630, P=0.000; t=29.380, P=0.000), p⁃P65 (t=24.370, P=0.000; t=13.460, P=0.000) and PDL1 (t=6.025, P=0.004; t=6.728, P=0.003) in si⁃P65⁃1 group and si⁃P65⁃2 group were lower than those in si⁃NC group. 6) There were statistically significant differences in the relative expression of p⁃P65 (F=269.700, P=0.000) and PDL1 (F=128.800, P=0.000) in U87 cells treated with different concentrations of drugs. P⁃P65 (t=19.750, P=0.000; t=24.640, P=0.000) and PDL1 (t=12.690, P=0.000; t=19.230, P=0.000) in ACT001 25 μmol/L group and 50 μmol/L group were lower than those in normal control group, ACT001 50 μmol/L group were also lower than those of 25 μmol/L group (t=5.288, P=0.006; t=2.868, P=0.046). Conclusions ACT001 can inhibit the proliferation of U87 glioma cells. By inhibiting the phosphorylation and nuclear translocation of P65 in U87 cells, ACT001 decreased the expression of PDL1 to improve the immunosuppressive environment of glioblastoma and thus inhibit the progression of glioblastoma.

Keywords

• glioblastoma
• sesquiterpenes
• nf⁃kappa b
• programmed cell death 1 receptor
• ligands
• cell proliferation
• transfection
• microscopy
• fluorescence
• immunoblotting
• tumor cells
• cultured