MAPK/ERK regulation of P53 in human epidermoid carcinoma cell line A431

Objective: To observe the impact of activation and inhibition of mitogen activated protein kinases (MAPK)/extracellular signalregulated protein kinase (ERK) signaling pathway on the proliferation and apoptosis of cutaneous squamous cell carcinoma (SCC). cells and investigate the interaction mechanism between MAPK/ERK signaling pathway and tumor suppressor gene P53 in SCC. Methods: Human A431 cells were cultured and divided into MAPK/ERK inhibition groups with low-, medium- and highconcentration of inhibitors (PD98059 + DMSO), MAPK/ERK activation groups with low-, medium- and high-concentration of stimuli (IGF + PBS) and blank control group (DMSO). The cell proliferation in vitro was detected by MTT assay, with the cell apoptosis detected by flow cytometry (FCM) and the protein expression of P-ERK and P53 detected by western blot in each group. Results: The A431 cell proliferation was inhibited by different concentrations of PD98059 with a clear concentration - effect and time - effect relationship ( p < .05); and the cell proliferation was promoted by the different concentrations of IGF with a clear concentration - effect and time - effect relationship ( p < .05). The FCM results showed a significant increase in the apoptosis rate of A431 cells which were treated with PD98059, with a clear concentration - effect relationship ( p < .05); while the apoptosis rate was decreased significantly after A431 cells were treated with IGF, also with a concentration - effect relationship ( p < .05). The western blot results showed that the expression of P-ERK protein was decreased but the expression of P53 was increased after A431 cells were treated with PD98059. With the concentration of PD98059 going up, the decrease in P-ERK and the increase in P53 were more significant ( p < .05); while the expression of P-ERK protein was increased but the expression of P53 was decreased after A431 cells were treated with IGF. With the concentration of IGF going up, the increase in P-ERK and the decrease in P53 were more significant ( p < .05). According to Pearson correlation analysis, the expression of P53 was negatively correlated to that of P-ERK ( p < .05). Conclusions: After MAPK/ERK signaling pathway was activated by IGF in A431 cells, the expression of pro-apoptotic factor P53 was decreased with the ability of cell proliferation enhanced and the ability of apoptosis reduced. However, after the inhibition of MAPK/ERK signaling pathway, the expression of pro-apoptotic factor P53 was increased with the ability of cell proliferation reduced and the ability of apoptosis increased.