Epithelial-mesenchymal transition in cervical cancer: correlation with tumor progression, epidermal growth factor receptor overexpression, and snail up-regulation.

PURPOSE: Acquisition of epithelial-mesenchymal transition (EMT) by primary carcinoma cells is associated with disrupted epithelial integrity, local invasion, and ultimately metastasis. Little is known about the existence and function of EMT in cervical cancer. This study aims to investigate the regulation of EMT in cervical squamous cell carcinoma. EXPERIMENTAL
DESIGN: We investigated the molecular events of EMT in surgical specimens, which present the progression of cervical carcinoma. Two cervical cancer cell lines and the primary culture of normal cervical epithelia were used to study the regulatory mechanisms of EMT.
RESULTS: The chronic epidermal growth factor (EGF) treatment induces the elongation of cell shape, increases cell scattering, and enhances cell invasion. EGF treatment down-regulates E-cadherin and up-regulates vimentin in cervical cancer cells. These characteristics are consistent with the morphologic changes, molecular events, and functional significance of EMT. EGF receptor (EGFR) signaling inactivates glycogen synthase kinase-3beta, which results in the nuclear accumulation of up-regulated Snail and then leads to EMT program. alpha(5)beta(1) integrin signaling and extracellular matrix fibronectin can modulate EGF-induced EMT. Importantly, the immunofluorescent stainings of surgical specimens indicate that cervical carcinoma progression is accompanied by EGFR overexpression, which is in parallel with decreased E-cadherin and increased vimentin. Up-regulation and nuclear accumulation of Snail correlate with EMT program in tumor tissues.
CONCLUSION: EGF cooperates with alpha(5)beta(1) integrin signaling to induce EMT in cervical cancer cells via up-regulated Snail. Blockade of EGFR activity or expression may provide a potential target for the treatment of cervical cancer progression.