Abstract: Objective To investigate the effects of rhLF on the proliferation and apoptosis in oral cancer KB cell line in order to achieve a new effective treatment for oral cancer patients. Methods KB cells were treated with different doses of rhLF (0,12.5,25,50,100,200 μg/mL) for 24,48,72 h and cell viability was detected by CCK-8 assay. Immunofluorescence was used to evaluate the expression of DNA damage associated protein γ-H2AX. Western blotting was performed to examine the expressions of γ-H2AX. Colony formation of the cells was observed after KB cells had been treated with rhLF at 0,200 μg/mL for 14 days. JC-1 assay was used to measure the changes in mitochondrial membrane potential, Annexin V-PI staining was used to observe the cell apoptosis. Western blotting was employed to detect the expressions of Parp and Caspase-3. Results rhLF caused significant suppression of KB cells proliferation. Immunofluorescence showed the increase of γ-H2AX after cells were incubated with rhLF. Western blotting displayed that the expressions of γ-H2AX gradually increased in dose-dependent. Meanwhile, rhLF significantly inhibited KB cells colony formation. Exposure to rhLF (0, 50, 200 μg/mL) after 48 h resulted in 2.02%, 7.60% and 48.07% cell apoptotic rates. Exposure of the cells to increased concentrations of rhLF gradually increased the apoptotic rate and decreased mitochondrial membrane potential. rhLF increased the expression of activated Parp, Caspase-3. Conclusion rhLF can inhibit the proliferation and induce apoptosis of KB cells, the rhLF of which may be associated with the activation of the mitochondrial apoptotic pathway.

Key words: oral cancer, Recombinate human lactoferrin, apoptosis