Objective    To investigate the effect of IRF-4 binding protein (IBP) on human salivary adenoid cystic carcinoma (SACC) cell proliferation.     Methods     IBP expression was detected and analyzed in 27 paraffin-embedded human SACC tissue specimens and 20 paraffin-embedded normal salivary gland tissue specimens with immunohistochemical staining (S-P method). ACC2 human SACC cells was transfected with plasmid pEGFP-C1/IBP (IBP group) and blank control plasmid pEGFP-C1 (control group) via lipofection. Then

the positive cells were screened with G418 to establish a cell strain with stable IBP overexpression. The effect of IBP on ACC2 cell proliferation was studied with MTT method and plate colony formation assay.     Results    IBP was positively expressed in all normal salivary gland tissue specimens

weakly expressed in 3 human SACC tissue specimens

and not expressed in other 24 SACC tissue specimens (IBP positive rate=11.11% in human SACC tissue specimens). The proliferation of ACC2 cells in the IBP group was significantly inhibited (P0.05). In addition

the colony formation assay results indicated that the colony formation rate of the IBP group was significantly lower than that of the control group (48% vs 92%

P0.05).     Conclusion    IBP can significantly inhibit SACC cell proliferation.