The upregulation of lysyl oxidase in oral submucous fibrosis and squamous cell carcinoma

Lysyl oxidase (LO) takes part in the initial steps of converting soluble mo nomers of collagen and elastin into insoluble fibres in the extracellular m atrix. We have studied the immunolocalization of LO as a marker of fibrogen esis in oral submucous fibrosis (OSF). Oral biopsies from 13 subjects with OSF, 6 with histologically confirmed squamous cell carcinoma (SCC) arising in OSF and 10 SCC nonrelated to OSF, were examined. Strong positive stainin g was observed in 7/13 OSF samples in the cytoplasmic processes of fibrobla sts and extracellularly in the upper third of the lamina propria. Furthermo re, LO was found to co-localize in the areas stained strongly for collagen and elastin by histochemical stains. Examination of SCC tissues showed loca lization of LO adjacent to invading epithelial islands as evidence of a str omal reaction both in carcinomas arising from OSF and in SCC from non-OSF c ases. These findings suggest that upregulation of LO may be an important fa ctor in the pathogenesis of OSF and in the early stromal reaction of oral c ancer.