Interleukin-6-induced epithelial-mesenchymal transition through signal transducer and activator of transcription 3 in human cervical carcinoma

Epithelial-mesenchymal transition (EMT) is an important process in the invasion and metastasis of human cervical carcinoma. The pro-inflammatory cytokine interleukin-6 (IL-6) has been shown as an EMT inducer in multiple carcinomas. However, whether the EMT program can be induced by IL-6 and the mechanisms underlying the IL-6-induced EMT in human cervical carcinoma remain to be determined. In this study, we show that IL-6 receptor (IL-6R) and signal transducer and activator of transcription 3 (Stat3) were highly expressed in human cervical squamous cell carcinoma (CSCC) tissues, and the expression of EMT markers was reversed in well-differentiated and poorly-differentiated human CSCC. Additional experiments showed that IL-6 exposure in cervical carcinoma cell lines induced IL-6R and Stat3 expression, markedly promoted cell growth, and altered cell morphology. The treatment of cervical carcinoma cell lines with IL-6 resulted in down-regulation of E-Cadherin and upregulation of Vimentin. Importantly, knockdown of Stat3 significantly reversed the IL-6-induced EMT program, suggesting that Stat3 is necessary for IL-6-induced EMT in the progression of human cervical carcinoma. Moreover, Slug, a member of the Snail family of EMT regulators, was observed to be associated with the expression of Stat3. We concluded that IL-6 plays an important role through Stat3 in the EMT induction and can be a potential therapeutic target and biomarker for human cervical carcinoma.