GCN5 Potentiates Glioma Proliferation and Invasion via STAT3 and AKT Signaling Pathways

Abstract

The general control of nucleotide synthesis 5 (GCN5), which is one kind of lysine acetyltransferases, regulates a number of cellular processes, such as cell proliferation, differentiation, cell cycle and DNA damage repair. However, its biological role in human glioma development remains elusive. In the present study, we firstly reported that GCN5 was frequently overexpressed in human glioma tissues and GCN5 was positively correlated with proliferation of cell nuclear antigen PCNA and matrix metallopeptidase MMP9. Meanwhile, down-regulation of GCN5 by siRNA interfering inhibited glioma cell proliferation and invasion. In addition, GCN5 knockdown reduced expression of p-STAT3, p-AKT, PCNA and MMP9 and increased the expression of p21 in glioma cells. In conclusion, GCN5 exhibited critical roles in glioma development by regulating cell proliferation and invasion, which suggested that GCN5 might be a potential molecular target for glioma treatment.

Keywords: GCN5; STAT3; cell invasion; cell proliferation.

Figure 1

GCN5 was frequently overexpressed in human glioma tissues. (A) Glioma and adjacent non-tumor tissue were pathologically diagnosed by HE staining; GCN5 expression in gliomas was determined by IHC (Magnification ×200); (B) GCN5, PCNA and MMP9 protein level were determined in 15 (Number1-15) pairs of glioma tissues by Western blot (N: Non-tumor tissue; T: Tumor tissue); (C) GCN5, PCNA and MMP9 were overexpressed in glioma tissues compared with adjacent non-tumor tissues both at protein and mRNA level; and (D) GCN5 protein level was positively associated with PCNA and MMP9 level, respectively; GCN5 protein level in high-grade group was much higher than in low-grade group tissues (* p < 0.05; ** p < 0.01).

Figure 1

GCN5 was frequently overexpressed in human glioma tissues. (A) Glioma and adjacent non-tumor tissue were pathologically diagnosed by HE staining; GCN5 expression in gliomas was determined by IHC (Magnification ×200); (B) GCN5, PCNA and MMP9 protein level were determined in 15 (Number1-15) pairs of glioma tissues by Western blot (N: Non-tumor tissue; T: Tumor tissue); (C) GCN5, PCNA and MMP9 were overexpressed in glioma tissues compared with adjacent non-tumor tissues both at protein and mRNA level; and (D) GCN5 protein level was positively associated with PCNA and MMP9 level, respectively; GCN5 protein level in high-grade group was much higher than in low-grade group tissues (* p < 0.05; ** p < 0.01).

Figure 2

GCN5 expression in glioma cell lines and cell cycle progression. (A) The expression of GCN5 in five glioma cell lines was determined by Western blot; and (B) GCN5 and PCNA expression pattern in serum starvation and releasing model experiment (* p < 0.05, compared with NO starvation).

Figure 3

GCN5 expression was suppressed after siRNA treatment. (A) Western blot showed that GCN5 protein level was significantly decreased after siRNA treatment. (B) RT-PCR showed that GCN5 mRNA level was significantly downregulated after siRNA treatment (* p < 0.05; ** p < 0.01).

Figure 4

GCN5 knockdown suppressed cell proliferation and colony formation ability. (A) MTS assay indicated that GCN5 knockdown suppressed cell growth rate in U251 and U87 cell lines; (B) Colony formation assay showed that GCN5 knockdown suppressed cell colony formation ability in U251 and U87 cell lines (* p < 0.05; ** p < 0.01).

Figure 5

GCN5 knockdown inhibited cell invasion. (A) Downregulation of GCN5 after siRNA treatment inhibited cell invasion in U251 and U87 cell lines (Magnification× 100); and (B) Quantification analysis showed that GCN5 knockdown could suppress cell invasion in U251 and U87 cell lines (* p < 0.05).

Figure 6

GCN5 knockdown decreased the expression of p-STAT3, p-AKT, PCNA, and MMP9 and increased the expression of p21 in glioma cells (* p < 0.05; ** p < 0.01).