CLINICOPATHOLOGICAL SIGNIFICANCE OF CATHEPSIN-B IMMUNOSTAINING IN TRANSITIONAL NEOPLASIA

Fifty Stage heterogeneous urinary bladder carcinomas were immunostaine d for cathepsin B, a lysosomal endoproteinase putatively associated wi th tumor invasion. Neoplastic cell CB immunoreactivity was strongly co rrelated to both grade (I/II-42% positive versus III-68% positive, P = 0.01) and invasion beyond the lamina propria (Ta/T1-42% positive vers us T2/T3-68% positive, P = 0.02). Most low grade, papillary tumors dis played a granular cytoplasmic staining pattern, compatible with lysoso mal distribution, in contrast to high grade tumors, in which diffuse s taining was present in the cytoplasm. Staining was also accentuated at the advancing front of invading tumors and in angiolymphatic tumor em boli. Non-neoplastic mononuclear inflammatory cells, particularly thos e at the host-tumor interface, displayed variable, sometimes intense s taining. Strong tumor-cell CB was more frequent among recurrent TCC th an in patients who remain free of disease (55% versus 29%, n = 18, T2- 3, cystectomy, 5-yr min. follow-up). We conclude these observed staini ng patterns and grade/stage associations are compatible with an import ant biological role for CB in facilitating host invasion in some bladd er tumors. Levels and/or distribution of CB may also be of potential v alue in defining clinically aggressive tumor subsets.