Background
Malignant transformation of oral lichen planus (OLP) was reported particularly in erosive type, however, it remains inconclusive. Cathepsin L was shown to promote tumor growth and invasion in many cancers. Therefore, cathepsin L expression in erosive and non-erosive OLP compared with oral epithelial dysplasia and oral squamous cell carcinoma (OSCC) were investigated.
Conclusion
According to the patterns of expression in this study, cathepsin L could be implicated in pathogenesis and severity of OLP.
Methods
Thirty specimens of OLP (15 cases each of erosive and non-erosive OLP), 10 cases of oral epithelial dysplasia and 10 cases of OSCC were included. Ten healthy gingiva specimens were served as controls. All specimens were stained with cathepsin L antibody using immunohistochemistry technique.
Results
Cathepsin L was expressed in all OLP and OSCC cases. In oral epithelial dysplasia and healthy gingiva, the expression was found at 90% and 50% respectively. The percentage of positive cells was the highest in erosive OLP (27.26 ± 12.09%), followed by non-erosive OLP (20.85 ± 7.43%), OSCC (20.15 ± 15.70%), oral epithelial dysplasia (9.24 ± 7.00%) and healthy gingiva (2.27 ± 5.65%). Most of non-erosive OLP cases showed mild staining intensity while erosive OLP and OSCC showed moderate staining intensity. Cathepsin L was mainly expressed at basement membrane zone and inflammatory cells of OLP. In OSCC, the expression was found in tumor islands and keratin pearls. In oral epithelial dysplasia and normal gingiva, cathepsin L expressions were low and presented in scattered pattern in both epithelium and connective tissue.