Abstract: PURPOSE: To investigate the effects and regulatory mechanisms of hyperthermia combined with silencing Id-1 gene on proliferation and invasion of tongue squamous cell carcinoma in vitro. METHODS: Cal-27 cells were divided into 4 groups. In silencing Id-1 group (Id-1-siRNA), siRNA was used to silence the expression of Id-1 in the CAL-27 cells, and the mRNA expression of Id-1 was detected by RT-PCR. In hyperthermia group (HT), CAL-27 cells were placed into constant temperature incubator at 42.5℃ for 40 minutes. In combined group (HT+Id-1-siRNA), hyperthermia combined with silencing Id-1 gene were exerted on CAL-27 cells. Normally cultured CAL-27 cells were used as control group. The proliferation and invasion ability were analyzed by CCK8 assay and Transwell chamber test,and the protein expression of PI3K, p-Akt was detected by Western blotting. SPSS 19.0 software package was used to analyze the data. RESULTS: The expression level of Id-1 mRNA decreased by 81.6% in the Id-1-siRNA group, compared with the blank control group. Both silencing Id-1 and hyperthermia not only inhibited the proliferation and invasion of CAL-27 cells（P<0.05）, but also down-regulated the protein expression of PI3K, p-Akt; however, the combination of hyperthermia and Id-1-siRNA contributed to more significant results. CONCLUSIONS: Hyperthermia in conjunction with silencing Id-1 could reduce the proliferation and invasion of CAL-27 cell line of tongue squamous cell carcinoma by down-regulating PI3K/Akt signaling pathway.

Key words: Tongue squamous cell carcinoma, Hyperthermia, Inhibitor of differentiation/DNA binding-1, Proliferation, Invasion, PI3K/Akt signaling pathway