Abstract: Qin Xuyan, Zang Yunshu, Pan Min, Yuan Mengshu, Yu Bo, Wu Huihui. Department of Dermatology, Affiliated Hospital of Qingdao University, Qingdao 266003, China Corresponding author: Pan Min, Email: pan730412@126.com 【Abstract】 Objective To investigate the cross-talk between extracellular signal-regulated kinase （ERK） and nuclear factor κB （NF-κB） signal transduction pathways in A375 human melanoma cells. Methods Cultured A375 cells were randomly divided into 5 groups: control group receiving no treatment, two U0126 （a selective inhibitor of the ERK signaling pathway） groups treated with U0126 of 10 and 5 μmol/L, and two BMS-345541 groups treated with BMS-345541 of 10 and 5 μmol/L. After 24-hour treatment, Western blot and reverse transcription PCR were performed to measure the protein expressions of NF-κB P65, phosphorylated IκBα （p-IκBα）, ERK1/2, as well as p-ERK1/2, and the mRNA expressions of NF-κB P65 and ERK1, respectively. One-way analysis of variance and least significant difference （LSD）-t test were carried out for statistical analysis. Results After 24 hours of treatment with U0126 of 10 and 5 μmol/L, a significant decrease was noted in the relative expression level of NF-κB p65 protein （0.60 ± 0.04 and 0.56 ± 0.06 vs. 1.54 ± 0.15, both P < 0.01） and mRNA （0.79 ± 0.05 and 0.75 ± 0.04 vs. 0.86 ± 0.05, both P < 0.01）, but a statistical increase in that of p-IκBα protein （0.90 ± 0.05 and 0.70 ± 0.02 vs. 0.61 ± 0.03, both P < 0.01） in the two U0126 groups compared with the control group; significant differences were observed in the expression level of p-IκBα protein （P < 0.01） but not in that of NF-κB p65 protein （P > 0.01） between the two U0126 groups. The relative expression levels of ERK1/2 and p-ERK1/2 proteins as well as ERK1 mRNA were significantly higher in the control A375 cells than those in the cells treated with BMS-345541 of 10 μmol/L （0.73 ± 0.07，0.75 ± 0.09，1.51 ± 0.02, all P < 0.01）, but similar to those treated with BMS-345541 of 5 μmol /L （0.94 ± 0.11, 0.99 ± 0.04，1.62 ± 0.03, all P > 0.05）. Conclusion There is a cross-talk between ERK and NF-κB signal transduction pathways in A375 melanoma cells.

Key words: Melanoma, NF-kappa B, Extracellular signal-regulated MAP kinase, Signal transducting