CATHEPSIN-B EXPRESSION AND ITS CORRELATION WITH TUMOR-ASSOCIATED LAMININ AND TUMOR PROGRESSION IN GASTRIC-CANCER

Objective.-Cathepsin B, a lysosomal cysteine proteinase, is associated with degradation of laminin. Its activity has been shown to be increa sed in gastric carcinomas. Laminin is one of the major components of b asement membrane involved in cell-matrix interactions and tumor progre ssion. The objectives of this study were to correlate cathepsin B expr ession in tumor cells with tumor-associated laminin and to further cor relate the two with tumor progression. Design and Setting.-Resected ga stric carcinomas (n = 29) taken from the surgical pathology files of t he University of Massachusetts Medical Center, Worcester, were immunos tained with cathepsin B and laminin using the avidin-biotin complex te chnique. Statistical analysis was performed using the exact linear by linear association test and exact Kruskal-Wallis test. Kaplan-Meier cu rves were plotted, and survival analysis was performed using a nonpara metric log-rank test. Results.-Cathepsin B was expressed in 27 (93%) o f 29 tumors (11 weak and 16 strong). Staining of tumor-associated lami nin showed patterns ranging from almost continuous (n = 4) to moderate ly discontinuous (n = Il)and highly fragmented (n = 14). The degree of cathepsin B staining in tumor cells significantly correlated with the laminin distribution pattern (P=.0001). The association between incre ased cathepsin B, decreased laminin, and higher tumor stage was also s ignificant. Conclusions.-Increased cathepsin B expression by tumor cel ls associated with decreased tumor-associated laminin may suggest a me chanism for local tumor progression and metastasis. Staining for cathe psin B and laminin may be of prognostic value In gastric carcinomas.