Abstract: PURPOSE: To observe the inhibitory effect of nimotuzumab combined with low-dose continuous irradiation using ¹²⁵I seeds on CAL-27 cells originating from human tongue squamous carcinoma, and explore the radiosensitization of nimotuzumab on human tongue squamous carcinoma CAL-27 irradiated with ¹²⁵I seeds. METHODS: The exponential-phase CAL-27 cells were randomly divided into 4 groups: control group, ¹²⁵I seeds irradiation group, nimotuzumab group, nimotuzumab plus ¹²⁵I seeds irradiation group. CCK-8 assay was used to detect the inhibitory effect of ¹²⁵I seeds irradiation on CAL-27 cancer cells, and flow cytometry assays were performed to calculate the apoptosis rate of cells and cell cycle from each group. The morphology of cells was compared using Hoechst 33258 staining. The data were analyzed with SPSS17.0 software package. RESULTS: ¹²⁵I seeds inhibited the growth of CAL-27 cells in time-dose dependent manner. The apoptosis rate of cells irradiated by nimotuzumab combined with ¹²⁵I seeds irradiation was higher than that treated with nimotuzumab and ¹²⁵I seeds irradiation respectively, and nimotuzumab followed by radiation had a lower S phase cells(P<0.05). CONCLUSIONS: Nimotuzumab combined with ¹²⁵I seeds irradiation killed CAL-27 cells by inducing apoptosis. Nimotuzumab and low-dose γ ray emitted from ¹²⁵I seeds can significantly enhance the radiosensitivity of CAL-27.

Key words: Nimotuzumab, Tongue squamous cell carcinoma, 125I seeds, Epidermal growth factor receptor, Radiosensitization