SPECIFIC EXPRESSION OF THE PANCREATIC-SECRETORY-TRYPSIN-INHIBITOR (PSTI) GENE IN HEPATOCELLULAR-CARCINOMA

Twenty hepatocellular carcinomas (HCC) were analyzed by Northern blott ing to test the expression of pancreatic secretory trypsin inhibitor ( PSTI). This gene was expressed in all HCCs, but not in other tumors, i ncluding mammary, thyroid, pulmonary and ovarian cancers. Some gastric and colonic cancers weakly expressed PSTI. Among cell lines examined in a similar manner, PSTI was expressed in all of 4 derived from hepat oma. On the other hand, among 15 cell lines derived from cancers other than hepatoma, only 3, derived from pancreatic, colonic and gastric c ancers, weakly expressed PSTI. A CAT assay using a deletion set of the 5' region from the cloned PSTI gene has shown that in hepatoma cell l ines, the expression of this gene is dependent on the presence of 2 re gulatory regions that include an IL-6 responsive element and an AP-I-b inding site. However, in non-hepatoma cell lines, the 2 regulatory reg ions are not necessary for expression. The blood level of PSTI in 27 p atients with HCC was significantly increased, and it was positively co rrelated with tumor size, suggesting that specific expression of PSTI in HCC causes this effect and that elevated blood level of PSTI withou t inflammation indicates the presence of HCC. (C) 1993 Wiley-Liss, Inc .