ABSTRACT
Objective:To observe the optimal time interval of multiple short-term hyperthermia in tongue squamous carcinoma Cal-27 cells, and investigate the role of Notch signaling pathway in hyperthermia-induced apoptosis of Cal-27 cells.Methods:Cal-27 cells were placed into a 42℃ incubator for 45 min, and the second hyperthermia was performed at 6 h,12 h, 24 h, 48 h and 72 h later, respectively. Cell proliferation capacity was detected by CCK-8 assay at 0 h, 12 h and 24 h after the end of hyperthermia. After determining the optimal time interval of hyperthermia, multiple cycles of hyperthermia were performed, and the effects of hyperthermia on the proliferation and apoptosis of Cal-27 cells were detected by CCK-8 assay and flow cytometry, respectively. The changes in the expression of Notch1, Jagged1 and hairy and enhancer of split homolog-1 (Hes1) mRNA and proteins were analyzed by real-time reverse transcription PCR (qRT-PCR) and Western blot. All data were expressed as mean±SD. Two-group comparison was performed by one-way ANOVA.Results:Hyperthermia at 42℃ for 45 min every 12 h consistently inhibited the proliferation of Cal-27 cells ( P<0.05). Compared with the control group, hyperthermia in the experiment group significantly inhibited the proliferation and induced the apoptosis of Cal-27 cells after 7 cycles of hyperthermia ( P<0.05), and the expression levels of Notch1, Jagged1 and Hes1 mRNA and proteins in the hyperthermia group were significantly down-regulated (all P<0.05). Conclusions:The optimal time interval of hyperthermia to inhibit the proliferation of tongue squamous cells carcinoma Cal-27 cells is 12 h. Hyperthermia might induce the apoptosis of Cal-27 cells by inhibiting the Notch signaling pathway.