Seneciphylline induced the autophagy of cervical cancer cells via MEK/ERK1/2 regulation

The purpose of this study was to explore the effects of seneciphylline on the proliferation and autophagy of cervical cancer HeLa and Caski cells and the possible mechanisms of autophagy. MTT assay was used to evaluate the effect of seneciphylline on the proliferation of cervical cancer cells. Immunofluorescence assay was applied to investigate the formation of autophagosomes in GFP-LC3/HeLa and GFP-LC3/Caski cells. The effect of seneciphylline on the expression of autophagy-related proteins was checked by Western blotting. In addition, fluorescence colocation assay was used to detect the fusion of autophagosomes and lysosomes. Human cervical cancer subcutaneous xenografts in nude mice were used to evaluate the effect of seneciphylline on the growth of the tumor in vivo. Results showed that HeLa cells proliferation was inhibited by seneciphylline in a dose- and time- dependent manner. Seneciphylline could induce formation of autophagosomes, increase the expression of LC3-II and decrease the expression of P62, suggesting that seneciphylline induced autophagy in HeLa and Caski cells. Compared with seneciphylline alone, seneciphylline combined with later-stage autophagy inhibitor chloroquine significantly increased the expression of LC3-II and P62. Moreover, and fluorescence colocation assay showed that autophagosomes induced by seneciphylline could colocate with lysosomes, indicating that seneciphylline could induce the complete autophagy flux. Compared with seneciphylline alone, seneciphylline combined with earlier-stage autophagy inhibitor 3MA significantly increased the expression of LC3-II and significantly decreased HeLa and Caski cells viability, suggesting that seneciphylline induced protective autophagy. Compared with seneciphylline alone, seneciphylline combined with MEK inhibitor significantly decreased the expression of P-ERK1/2 and formation of autophagosomes, suggesting that autophagy induced by seneciphylline activated MEK/ERK1/2 signal pathway. In addition, seneciphylline showed a significant inhibitory effect on growth of human cervical cancer cells subcutaneous xenografts.