Immunohistochemical distributions of cathepsin B and basement membrane antigens in human lung adenocarcinoma: association with invasion and metastasis.

The distributions of cathepsin B (CB) a lysosomal cysteine proteinase, type IV collagen (CIV) and laminin (LM), which are main components of basement membranes (BMs) were studied in a series of 64 human lung adenocarcinomas using an immunohistochemical technique. Over-expression of CB (> 80% positive cells) was significantly associated with the grade of tumour differentiation (p < 0.01), with lymph node metastasis (p < 0.01) and with BM degradation (p < 0.01) detected by the staining pattern of CIV and LM. It was significantly associated with a prognostic disadvantage (p < 0.01). The immunohistochemical staining pattern of CB has a close relationship with degradation of BM, and may be used as a marker for tumour metastasis and prognosis in lung adenocarcinoma.