사람 유래 FaDu 하인두 편평세포암에서 아데노신의 mTOR 인산화에 관여한 세포성장 억제

Abstract

The akt/mammalian target of rapamycin (mTOR) signal transduction is considered to be a central regulator of protein synthesis, involving the regulation of cell proliferation, differentiation, and survival in cancer cells. The inhibitors of mTOR as anticancer reagents are undergoing active evaluation in various cancer cells. However, akt/mTOR signal transduction in human head and neck squamous carcinoma for adenosine effect remain unknown. This study performed to understand a akt/mTOR signal transduction of adenosine-induced cell death in human FaDu hypopharynx squamous cell carcinoma. To verify the cell viability and cytopathic effect of adenosine in human FaDu cells, MTT assay and crystal violet staining were performed. To understand the mechanism of cell death by adenosine treatment in cells, DNA fragmentation and western blot analysis were examined. Adenosine reduced FaDu cell viability in a concentration (1.5 mM, 3.0 mM) compared with untreated with adenosine (p<0.01, ANOVA) for 24 h and cell staining was gradually reduced, which indicated the elevation of cytopathic effect for adenosine in FaDu cells. After treatment with adenosine (1.5 mM, 3.0 mM) for 24 h, FaDu cells harvested and then confirmed apoptosis by DNA fragmentaion assay. A DNA ladder formation was clearly found with cells adenosine (3.0 mM) treatment for 24 h, indicating that adenosine induces apoptosis in FaDu cells. Moreover, to understand mTOR signal transduction for adenosine effect underlying the inhibition of cell growth in FaDu cell, western blot analysis was performed. Adenosine significantly decreased phosphorylation of PI3K, akt, mTOR, 4E-BP1 and S6-ribosomal protein. It also downregulated Bcl-2 expression and then caused activation of caspase-9, the effector caspase-3 and PARP cleavage. This present study demonstrates that adenosine can negatively regulate akt-mTOR pathways, which is associated with cell proliferation. It also suggest that cell proliferation inhibits by a novel signal transduction for adenosine effect in human FaDu hypopharynx squamous cell carcinoma cells.