Mutations in the <i>PRSS1</i> (serine protease 1) gene encoding human cationic trypsinogen cause hereditary pancreatitis or may be associated with sporadic chronic pancreatitis.
Hereditary pancreatitis (HP), an autosomal dominant disease typically caused by mutations in PRSS1, has a broad range of clinical characteristics and high cumulative risk of pancreatic cancer.
Despite 90% identity with PRSS1 and a strong propensity for autoactivation, mutations in PRSS2 are not found in hereditary pancreatitis suggesting that activation of this isoform is more tightly regulated.
A mutation in the PRSS1 gene is present in greater than 70% of HP kindreds and leads to a gain-of-function characterized by the increased autocatalytic conversion of trypsinogen to active trypsin, promoting autodigestion and damage to acinar cells.
Hereditary pancreatitis is caused by mutations in human cationic trypsinogen (PRSS1) which lead to increased autoactivation by altering chymotrypsin C (CTRC)-dependent trypsinogen activation and degradation.
Since the identification of mutations in the cationic trypsinogen (PRSS1) gene as a cause of hereditary pancreatitis in 1996, we have seen great progress in our understanding of the genetics of pancreatitis.
Robust autoactivation, chymotrypsin C independence and diminished secretion define a subset of hereditary pancreatitis-associated cationic trypsinogen mutants.
Using recombinant normal sequence PSTI/tumor-associated trypsin inhibitor (TATI), a variant associated with familial pancreatitis (N34S), an active site-inactivated variant (R18/V19), and immunoneutralization and RNA interference-mediated knockdown techniques, we investigated the actions of PSTI/TATI on cell migration (wounding monolayers), collagen invasion (gel invasion assays), and proliferation (Alamar blue) on 253J, RT4, and HT1376 human bladder carcinoma cell lines.
Four patients had hereditary pancreatitis (three with confirmed N34S mutation in the SPINK1 gene), one patient had chronic pancreatitis of unknown etiology, and one patient with annular pancreas developed obstructive chronic pancreatitis.
We found that in the presence of CTRC, trypsinogen mutants associated with classic hereditary pancreatitis (N29I, N29T, V39A, R122C, and R122H) autoactivated at increased rates and reached markedly higher active trypsin levels compared with wild-type cationic trypsinogen.
We believe that interaction between the novel IVS3+172 intronic variant and p.N29I mutation in the PRSS1 gene is associated with HP in this Malaysian Chinese family.
The etiology of acute pancreatitis (AP) seems to have changed during the last two decades, and since detection of mutations in the gene for cationic trypsinogen(PRSS1) causing hereditary pancreatitis some patients formerly diagnosed with idiopathic AP (IAP) turn out to have a genetic cause.
The occurrence of exocrine and endocrine insufficiency is higher among patients with HP than in patients with SPINK1-CFTR mutations and tIP, and more HP families develop pancreatic cancer.