Fig 2: Expression levels of PAICS protein in different glioma tissues. A, Representative PAICS staining in I-II grade, III grade, IV grade glioma tissues and adjacent normal brain tissues. Scale bar, 100 µm. B, The PAICS score was calculated as introduced in materials and methods part. *P < .05;***P < .001

Fig 3: Knockdown of PAICS in glioma cells inhibit cell cycle and promote apoptosis in vitro. A, Cell cycle was analysed by flow cytometry after knocking down PAICS. The results showed that PAICS depletion led G1 arrest. B, Cell apoptosis was analysed by flow cytometry after knocking down PAICS. The results showed that PAICS depletion leading to an increased rate of apoptosis. ***P < .001

Fig 4: PAICS regulates the genes expression of NER pathway. A, The expression of ERCC1 and XPA in U87 and U251 cells was detected by qRT-PCR after inhibiting the expression of PAICS. ERCC1 and XPA expression level was normalized to GAPDH. Error bars represent the mean ± SD of three independent experiments. The differences between independent experimental groups were tested by using independent-samples t test. *P < .05. B, The expression of PAICS, ERCC1 and XPA in U87 and U251 cells was detected by Western blot after decreasing the expression of PAICS. GAPDH served as the loading control. Error bars represent the mean ± SD of three independent experiments. The differences between independent experimental groups were tested by using independent-samples t test. **P < .01; ***P < .001

Fig 5: l-aspartic acid inhibits proliferation of glioma cells by regulating the expression of PAICS. A, At 0, 24, 48 and 96 h, RT-qPCR was used to detect PAICS gene expression in the l-aspartic acid group, the PAICS interference fragment group and the control group were detected, respectively. ***P < .001. B, At 0, 24, 48, and 96 h, Western blot was used to detect PAICS gene expression in the diffient group. ***P < .001. C, RT-qPCR was performed to detect PAICS expression after adding l-aspartic acid. *P< .05; **P < .01; ***P < .001. D, Western blot was performed to detect PAICS expression after adding l-aspartic acid. ***P < .001. E, Effects of different concentrations of l-aspartic acid (3, 6, 9, 12 and 15 mmol/L) and DMSO on cell proliferation were determined by CCK8 cell proliferation assay. F, CCK8 was performed to detect PAICS proliferation in different group. **P < .01; ***P < .001