Human papillomavirus type 16 oncoprotein E7 suppresses cadherin-mediated cell adhesion via ERK and AP-1 signaling.

Human papillomaviruses (HPV) are the main etiological factor for cervical carcinoma. HPV-16 is the most prevalent high-risk HPV-genotype found in HPV-associated cancers. We studied the effect of HPV-16 E7 oncoprotein on cadherin-mediated cell adhesion. The expression of E7 strongly suppressed the cadherin-mediated cell adhesion in the rat fibroblast cell line 3Y1. This suppression was associated with the decreased expression of N-cadherin at the transcriptional level. The treatment of 3Y1 cells that express E7 (E7-3Y1) with MEK inhibitor recovered the cadherin-mediated cell adhesion together with the accumulation of N-cadherin at the cell-cell contact site. Moreover, the suppression of c-Jun, which is the element of AP-1 transcriptional factor, leads to the recovery of N-cadherin expression and cadherin-mediated cell adhesion in E7-3Y1 cells. Taken together, our results demonstrate that E7 regulates cadherin-mediated cell adhesion through the modulation of cadherin expression via the MEK-ERK and AP-1 signaling pathway.