HPV16-E6 Influences Growth and Apoptosis of Cervical Cancer Cells Through Up-regulation of MIF

Objective To investigate the effect of human papillomavirus oncogene E6(HPV16-E6) on the growth and apoptosis of cervical cancer cells via macrophage migration inhibitory factor(MIF).

Methods Cervical cancer cells C33A, SiHa and Caski which could secrete MIF were transfected with HPV16-E6 overexpression vector or shRNA; Western blot, qRT-PCR and ELISA were used to examine MIF protein and mRNA expression and its supernatant. The cells above were co-cultured with human macrophages, and then we detected the expression of MIF in macrophages. MIF inhibitor was added or not in C33A group which was transfected with HPV16-E6; the cell proliferation, cell cycle and apoptosis were detected by CCK-8 method and flow cytometry. The association of HPV16-E6 expression with MIF and survival were analyzed using Pearson and Kaplan-Meier methods.

Results The expression of MIF in cervical cancer cells, supernatant and macrophages were increased or decreased by up-regulation or down-regulation of HPV16-E6 expression(P < 0.05). HPV16-E6 over-expression could induce C33A cells proliferation, shorten G₀/G₁ phase and inhibit cell apoptosis, and these effects were reversed using MIF inhibitor(P < 0.05). There was positive correlation between HPV16-E6 expression and MIF in cervical cancer tissues(P < 0.05). Survival analysis suggested the expression of HPV16-E6 in cervical cancer tissues had a significant relationship with overall survival rate and progression-free survival rate(P < 0.05).

Conclusion HPV16-E6 could induce the expression of MIF in cervical cancer cells and macrophages, promote the growth and inhibit the apoptosis of cervical cancer cells through up-regulation of MIF.