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.


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 (≥0.5μg/mL) significantly inhibited the cell proliferation and induced the cell apoptosis, while the treatment with low-dose BLM (0.05 and 0.1μg/mL) for 48h induced EMT in HSG cells. Furthermore, Akt/mTOR pathway, rather than MAPK pathway, was activated through treated with 0.05 and 0.1μg/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 0.1μg/mL BLM, but the ability of acinar differentiation was diminished.


CONCLUSIONS
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.
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedical Engineering of Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China; Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, PR China.
Yu
Y
Cai
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedical Engineering of Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China.
Rui
R
Sun
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedical Engineering of Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China.
Rong
R
Wang
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedical Engineering of Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China; Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, PR China.
Jian-Gang
JG
Ren
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedical Engineering of Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China; Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, PR China.
Wei
W
Zhang
Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, PR China.
Yi-Fang
YF
Zhao
Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, PR China. Electronic address: jhzhao988@whu.edu.cn.
Ji-Hong
JH
Zhao
D017209:Apoptosis / Q000187:drug effects; D001761:Bleomycin / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D006801:Humans; D009078:Mucocele / Q000188:drug therapy* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012469:Salivary Glands / Q000187:drug effects* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013363:Submandibular Gland / Q000187:drug effects* / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
D014157:Transcription Factors; D001761:Bleomycin; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases
Akt/mTOR pathway; Bleomycin; Epithelial-to-mesenchymal transition; HSG cells