GADD45A 通过 p38 MAPK 途径诱导 G2/M 阻滞并抑制肿瘤增殖的机制

Abstract: Objective The present study aims to explore the role of the GADD45A gene in cell cycle regulation and its mechanism underlying tumor initation and progression. Methods To investigate the functional role of GADD45A in HCT116 cells, small interfering RNA (siRNA) technology was employed to specifically knock down its expression. Subsequently, cell cycle distribution was assessed using flow cytometry. The mRNA expression levels of cell cycle-related genes, including Cyclin B1 and CDK1, were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). Furthermore, Western Blot analysis was conducted to evaluate the protein expression levels of phosphorylated p38 (p-p38, Thr180/Tyr182), p-CDK1 (Tyr15), and total p38. Results The proportion of cells in the G0/G1 phase in the si-GADD45A group of HCT116 cells was significantly lower than that in the si-NC group, while the proportion of cells in the G2/M phase increased (P＜0.05). Compared with the si-GADD45A group, the proportion of cells in the G0/G1 phase in the si-GADD45A + SB203580 group was upregulated, while the proportion of cells in the G2/M phase was decreased (P＜0.05). The results of the qRT-PCR experiment showed that compared with the si-NC group, the expression levels of Cyclin B1 mRNA and CDK1 mRNA in the si-GADD45A group were significantly lower. The Western Blot results further revealed that the protein level of p-p38 was higher in the si-GADD45A group than in the si-NC group (P＜0.05), while there was no significant change in the total p38 protein levels between the groups (P＞0.05). The nude mouse transplantation tumor experiment showed that compared with the si-NC group, the tumor volume and tumor weight in the si-GADD45A group were significantly lower at day 21, and the proportion of necrotic area was significantly increased (P＜0.05). Conclusion The absence of GADD45A enhances the activity of CDK1 by activating mitogen-activated protein kinase (p38 MAPK) phosphorylation, specifically inducing G2/ M phase arrest, and thereby inhibiting tumor proliferation.