Immunohistochemical Detection of Pancreatic Secretory Trypsin Inhibitor (PSTI) in Urothelial Cancer

Pancreatic secretory trypsin inhibitor (PSTI), a specific trypsin inhibitor secreted by acinar cells of pancreas, also acts as a growth factor. PSTI in various cancers has been reported to be associated with tumor invasiveness and pathological malignancy; however, such studies in urological cancers have not yet been performed. We therefore examined the expression of PSTI in fresh frozen specimens of urothelial cancers immunohistochemically, using a polyclonal antibody. In 59 tumors (30 urinary bladder cancers, 16 ureteral cancers, and 13 renal pelvic cancers), 28 (47%) showed positive staining. In 44 transitional cell carcinomas (TCC), immunopositive tumor cells were observed in 16 (36%). However, there were no obvious differences in the incidence of PSTI expression among stages and grades. In 12 tumors with squamous cell cancer (SCC) cells, 10 tumors (83%) showed intense positive staining in see cells. These results suggest that the degree of expression of PSTI might be used for prognostic purposes since the prognosis of urothelial sec patients has been reported to be significantly poorer than that of TCC ones.