Laminin-5 gamma 2: a marker to identify oral mucosal lesions at risk for tumor development?

Mucosal lesions of various types are frequently encountered in the oral cavity and a limited proportion of these will eventually progress to invasive cancer. Neither macroscopic nor microscopic evaluation can give reliable information concerning risk for cancer development which is why a marker indicating high risk for tumor progression would be of significant value. Laminins are a family of alpha beta gamma heterotrimeric proteins found in basement membranes and earlier studies have shown that laminin-5 gamma 2 expression is a useful marker of invasiveness in head and neck squamous cell carcinomas. Unique material comprising 36 different oral mucosal lesions from 15 patients, prior to the development of invasive carcinoma (12 cases) or cancer in situ (CIS) (3 cases) on the same site, was investigated. For controls we had mucosal lesions from 15 patients without malignant progression. These 15 lesions matched with the specific site in the oral cavity of the initial patients. The minimum follow-up time for the control group was at least 36 months. We performed immunohistochemical staining with a monoclonal antibody against the recombinant gamma 2 chain of laminin-5 in the archived biopsies of preneoplastic oral lesions. Nine out of 15 cases of preneoplastic lesions which became invasive/CIS were laminin-5-positive (60%) whereas only 3 out of 13 (2 were excluded due to sparse material for laminin-5 analysis) lesions which did not progress were laminin-5-positive (23%) (p = 0.05). The results indicate that oral mucosal lesions expressing laminin-5 show an increased risk for tumor progression.