The activation of Akt/mTOR pathway by bleomycin in Epithelial-to-mesenchymal transition of human submandibular gland cells: A treatment mechanism of bleomycin for mucoceles of the salivary glands

Objective: Bleomycin (BLM) has been found safe and highly effective in the treatment of the mucoceles by intralesional injection in our previous study. The present research was designed to investigate whether epithelial-to-mesenchymal transition (EMT) contributes to the therapeutic effects of BLM for mucoceles of the salivary glands. Material and methods: The cell proliferation and apoptosis of human submandibular gland cells (HSG cells) were examined by Cell Counting Kit-8 assay and Annexin V binding assay respectively. Epithelial and mesenchymal markers of HSG cells were measured by real-time quantitative PCR and Western blot analysis. Acinar differentiation and cell migration assays were performed to evaluate HSG cells function. Results: High-dose BLM (>= 0.5 mu g/mL) significantly inhibited the cell proliferation and induced the cell apoptosis, while the treatment with low-dose BLM (0.05 and 0.1 mu g/mL) for 48 h induced EMT in HSG cells. Furthermore, Akt/mTOR pathway, rather than MAPK pathway, was activated through treated with 0.05 and 0.1 mu g/mL BLM, as well as activation of the transcription factor Slug and Zeb 1. The migration of HSG cells was also enhanced through 0.05 and 0.1 mu g/mL BLM, but the ability of acinar differentiation was diminished. Conclusion: Our results indicated that an EMT process was involved in the BLM-induced therapeutic effects on the HSG cells through the Akt/mTOR pathway. Importantly, the results indicated the potential role of this process in the BLM sclerotherapy of mucoceles of the salivary glands. (C) 2017 Elsevier Masson SAS. All rights reserved.