In most types of human cancer, inactivation of pRb/E2F complexes occurs, and released E2Fs initiate transcription of genes required for cell cycle progression. Evidence reveals that phosphorylated pRb deregulates E2F-1, and the levels of E2F-1 expression can accurately predict prognosis of oral squamous cell carcinoma (OSCC). Paradoxically, numerous reports indicate that E2F-1 is also capable of inducing apoptosis under certain cellular circumstances. In the present study, lentivirus-mediated shRNA was used to downregulate endogenous E2F-1 expression in order to study the function of E2F-1 in the pRb/E2F-1 pathway in the OSCC cell line Tca8113, and to investigate the alteration of Tca8113 cells in proliferation and apoptosis. The data from real-time quantitative RT-PCR and Western blot analysis showed that E2F-1-shRNA led to the inhibition of endogenous E2F-1 mRNA and protein expression, and E2F-1 may be associated with proliferation and apoptosis pathways. Growth kinetics data showed that Tca8113-E2F-1-shRNA cells presented more active proliferation properties than Tca8113-NC cells, and flow cytometry data demonstrated that the percentages of cells in the G1 phase, G2 phase and undergoing apoptosis differed between groups. In conclusion, silencing of E2F-1 inhibits proliferation and induces apoptosis. E2F-1 may also be involved in multi-level regulation networks; therefore, its role in OSCC requires further clarification.

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