Laminin γ2 chain expression in squamous cell carcinomas of the tongue and its clinical relevance

Laminin γ2 chain (LNγ2) expression and its clinical relevance were examined in squamous cell carcinomas of the tongue. When tumor cells were attached to each other and showed expansive growth, LNγ2 was expressed only in the peripheral cells of the tumor nests (peripheral expression). In contrast, when tumor cells showed infiltrative growth diminishing cell-cell adhesion, LNγ2 expression was diffusely observed in almost all of the cells (diffuse expression). Patients with caricinoma cells of the primary lesions showing peripheral LNγ2 expression were classified as the peripheral expression type, whereas patients with carcinoma cells showing diffuse LNγ2 expression at least in part of the invasive fronts were classified as the diffuse expression type. Among 30 patients with tongue carcinomas of more than stage II, 19 patients were the peripheral expression type and 11 patients were the diffuse expression type. The 3-year disease-specific survival rates for the peripheral type and diffuse type were 64% and 34%, respectively. LNγ2 may play an important role in growth and invasion of tongue carcinomas. In particular, it seems likely that the diffuse LNγ2 expression in carcinoma cells has a significant relevance to the malignant characteristics of infiltrative carcinoma cells. In addition, LNγ2 expression may be a useful prognostic factor for the patients with carcinomas of the tongue.