Objective: Oral submucous fibrosis (OSF) is a pre-malignant fibrotic lesion of the mouth in areca quid chewers. It is probably a consequence of disturbances in the hemeostatic equilibrium between synthesis and degradation of extracellular matrix molecules. Recently, we found that plasminogen activator inhibitor-1 (PAI-1) mRNA and protein were be upregulation in OSF (Oral Oncology 2003:367？V72). However, the detailed molecular mechanism is stilled remained to be elucidated. Methods: In this study, we investigated the genetic analysis of PAI-1 in the upstream -675bp of the promoter region between OSF and normal buccal mucosa. PAI-1 genotyping with allele-specific restriction enzyme site analysis was performed in the specimens from 52 OSF and 32 normal buccal mucosa. The Chi-square test was used as statistical analysis in this study. Results: There is a single guanosine deletion/insertion 4G/5G polymorphism -675 bp upstream from the start of transcription within the promoter. Our findings suggested that the distribution pattern of PAI-1 promoter were different between OSF and normal buccal mucosa (P< 0.05). It had a high frequency of PAI-1 (4G/4G) genotypes in the OSF group (42.3%) than those in normal buccal mucosa group (21.9%). The ratio of 4G/5G from OSF and normal buccal mucosa were 44.2% and 46.9%. In addition, the ratio of 5G/5G was 13.5%, 31.2% respectively. Conclusions: We concluded the results that PAI-1 4G allele, with a higher transcription activity, was more prevalent in OSF. This may be the molecular mechanism associated with an increased risk for OSF.
