Clonal evaluation of early onset prostate cancer by expression profiling of ERG, SPINK1, ETV1, and ETV4 on whole-mount radical prostatectomy tissue

BACKGROUND

Expression profiles of erythroblast transformation-specific (ETS)-related gene fusions and serine protease inhibitor Kazal-type 1 (SPINK1) in early onset prostate cancer have not been thoroughly explored.

METHODS

We retrieved 151 radical prostatectomy specimens from young men with prostate cancer (<55 years) and characterized the expression of ETS-related gene (ERG), SPINK1, ETS Variant 1 (ETV1), and ETV4 by dual immunohistochemistry and dual RNA in situ hybridization. Age, race, family history, preoperative prostate-specific antigen, biochemical recurrence, and pathological variables using whole-mount radical prostatectomy tissue were collected.

RESULTS

A total of 313 tumor nodules from 151 men including 68 (45%) Caucasians and 61 (40%) African Americans were included in the analysis. Positive family history of prostate cancer was seen in 65 (43%) patients. Preoperative prostate-specific antigen ranged from 0.3 to 52.7 ng/mL (mean = 7.04). The follow-up period ranged from 1 to 123.7 months (mean = 30.3). Biochemical recurrence was encountered in 8 of 151 (5%). ERG overexpression was observed in 85 of 151 (56%) cases, followed by SPINK1 in 61 of 151 (40%), ETV1 in 9 of 149 (6%), and ETV4 in 4 of 141 (3%). There were 25 of 151 (17%) cases showing both ERG and SPINK1 overexpression within different regions of either the same tumor focus or different foci. Higher frequency of ERG overexpression was seen in younger patients (≤45 years old; 76% vs 49%, P = .002), Caucasian men (71% vs 41% P = .0007), organ-confined tumors (64% vs 33%, P = .0008), and tumors of Gleason Grade groups 1 and 2 (62% vs 26%, P = .009). SPINK1 overexpression was more in African American men (68% vs 26%, P = .00008), in tumors with high tumor volume (>20%) and with anterior located tumors. ETV1 and ETV4 demonstrated rare overexpression in these tumors, particularly in the higher-grade tumors.

CONCLUSION

This study expands the knowledge of the clonal evolution of multifocal cancer in young patients and support differences in relation to racial background and genetics of prostate cancer.

Comparison of ERG and SPINK1 expression among incidental and metastatic prostate cancer in Japanese men

BACKGROUND

TMPRSS2:ERG fusion is the most common genetic event in prostate cancer (PCa). However, its association with prognosis is controversial. Overexpression of serine protease inhibitor Kazal-type 1 (SPINK1) was almost exclusively defined in ERG-negative PCa in most studies. This study aimed to determine the association between ERG and SPINK1 expression and the biological aggressiveness of PCa by analyzing their expression in incidental and metastatic cohorts.

METHODS

A total of 143 cystoprostatectomy specimens of invasive bladder cancer and 98 biopsy specimens from de novo metastatic PCa were analyzed. The prostate gland of cystoprostatectomy specimens was fixed and sliced in step sections. Immunohistochemistry of ERG and SPINK1 was conducted, and the results were correlated with the clinicopathological characteristics of the patients.

RESULTS

The overall prevalence of incidental cancer was 32.2% (46/143). The frequencies of both ERG and SPINK1 expression were not significantly different between incidental and metastatic cohorts (15.2% and 14.3%; P = 1.00, and 6.5% and 12.2%; P = 0.38, respectively). In the metastatic cohort, any pre-treatment factors were not significantly associated with the frequencies of ERG and SPINK1 expression. However, SPINK1 expression was significantly associated with a shorter time to castration-resistant PCa (CRPC) (P = 0.048). Meanwhile, overall survival was not significantly associated with the expression status of ERG and SPINK1 (P = 0.71).

CONCLUSIONS

ERG and SPINK1 expression may not have significant influence on the metastatic behavior of PCa. SPINK1 expression was significantly associated with a shorter time to CRPC in metastatic PCa. The expression profile of ERG and SPINK1 may be a useful predictor for effect of androgen deprivation therapy in patients with metastatic castration-sensitive PCa.

Differential expression of Annexin 2, SPINK1, and Hsp60 predict progression of prostate cancer through bifurcated WHO Gleason score categories in African American men

BACKGROUND

Although studies have observed several markers correlate with progression of prostate cancer (PCa), no specific markers have been identified that accurately predict the progression of this disease, even in African American (AA) men who are generally at higher risk than other ethnic groups. The primary goal of this study was to explore whether three markers could predict the progression of PCa.

METHOD

We investigated protein expression of Annexin 2 (ANX2), serine peptidase inhibitor, kazal type 1(SPINK1)/tumor-associated trypsin inhibitor (TATI), and heat shock protein 60 (Hsp60) in 79 archival human prostate trans-rectal ultrasound (TRUS) biopsy tissues according to a modified World Health Organization (WHO) classification: normal (WHO1a), Gleason Score (GS6 (WHO1b), GS7 subgroups (WHO2 = 3 + 4, WHO3 = 4 + 3), GS8 (WHO4), and GS9-10 (WHO5). AA men aged 41-90 diagnosed from 1990 to 2013 at Howard University were included. Automated staining assessed expression of each biomarker. Spearman correlation assessed the direction and relationship between biomarkers, WHO and modified WHO GS, age, and 5-year survival. A two-tailed t-test and ANOVA evaluated biomarkers expression in relationship to WHO normal and other GS levels, and between WHO GS levels. A logistic and linear regression analysis examined the relationship between biomarker score and WHO GS categories. Kaplan-Meier curves graphed survival.

RESULTS

ANX2 expression decreased monotonically with the progression of PCa while expression of SPINK1/TATI and Hsp60 increased but had a more WHO GS-specific effect; SPINK1/TATI differed between normal and GS 2-6 and HSP60 differed between GS 7 and GS 2-6. WHO GS was found to be significantly and negatively associated with ANX2, and positively with SPINK1/TATI and Hsp60 expression. High SPINK1/TATI expression together with the low ANX2 expression at higher GS exhibited a bi-directional relationship that is associated with PCa progression and survival.

CONCLUSION

Importantly, the data reveal that ANX2, and SPINK1/TAT1 highly associate with WHO GS and with the transition from one stage of PrCa to the next in AA men. Future research is needed in biracial and larger population studies to confirm this dynamic relationship between ANX2 and SPINK1 as independent predictors of PCa progression in all men.

Aberrant Activation of a Gastrointestinal Transcriptional Circuit in Prostate Cancer Mediates Castration Resistance

Prostate cancer exhibits a lineage-specific dependence on androgen signaling. Castration resistance involves reactivation of androgen signaling or activation of alternative lineage programs to bypass androgen requirement. We describe an aberrant gastrointestinal-lineage transcriptome expressed in ∼5% of primary prostate cancer that is characterized by abbreviated response to androgen-deprivation therapy and in ∼30% of castration-resistant prostate cancer. This program is governed by a transcriptional circuit consisting of HNF4G and HNF1A. Cistrome and chromatin analyses revealed that HNF4G is a pioneer factor that generates and maintains enhancer landscape at gastrointestinal-lineage genes, independent of androgen-receptor signaling. In HNF4G/HNF1A-double-negative prostate cancer, exogenous expression of HNF4G at physiologic levels recapitulates the gastrointestinal transcriptome, chromatin landscape, and leads to relative castration resistance.

Comparison of the prognostic value of a panel of tissue tumor markers and established clinicopathological factors in patients with gastric cancer

AIM

The purpose of this study was to assess if the addition of a panel of tumor markers to established clinicopathological factors could improve the accuracy of 5-year outcome prediction in gastric cancer. The studied markers were chosen to represent different aspects of tumor biology.

PATIENTS AND METHODS

The expression of syndecan-1, tenascin-C, tumor-associated trypsin inhibitor (TATI), p53, p21 and bcl-2 was analyzed by immunohistochemistry informalin-fixed, paraffin-embedded specimens from 337 patients with gastric cancer. In addition, the DNA ploidy and S-phase fraction (SPF) were assessed by flow cytometry.

RESULTS

The loss of epithelial syndecan-1, strong stromal syndecan-1, the loss of stromal tenascin-C, the loss of tumor tissue TATI, high p53 and high p21 expression, aneuploidy and high (> or =7.6%) SPF were all associated with an unfavorable prognosis in univariate survival analysis. In multivariate survival analysis, p53 (hazard ratio (HR) 1.58; confidence interval (CI) 95% 1.16-2.16), p21 (HR 1.67; CI 95% 1.09-2.56) and DNA ploidy (HR 1.50; CI 95% 1.10-2.05) were independent prognostic factors, in addition to penetration depth (pT), lymph node status (pN), age at diagnosis and estimated radicality of surgery. The difference in prognostic accuracy between a base model with pT, pN, age and radicality of surgery (area under the curve (AUC) 0.898; CI 95% 0.86-0.94) and an extended model including p53, p21 and DNA ploidy (AUC 0.900; CI 95% 0.86-0.94) was not statistically significant (p=0.85).

CONCLUSION

In gastric cancer, p53 and p21 expression, as well as DNA ploidy, are independent prognostic factors in addition to standard clinicopathological factors. However, the established indicators of the extent of disease show an impressively high accuracy in 5-year outcome prediction and adding the examined tumor markers to the base model does not significantly improve the prognostic accuracy.

Differential expression of trypsinogen and tumor-associated trypsin inhibitor (TATI) in bladder cancer

Tumor-associated trypsin inhibitor (TATI) is a marker of mucinous ovarian carcinoma, but it is also widely expressed in other malignant tumors and normal human tissues. Elevated serum concentrations of TATI are of prognostic value in ovarian, kidney, and bladder cancer. Tumor-associated trypsin is co-expressed with TATI in many malignancies and is thought to be involved in tumor invasion. TATI mRNA has been shown to be overexpressed in bladder cancer. We therefore studied whether trypsinogen expression also can be detected in bladder cancer and how this and TATI expression are associated with the clinicopathological characteristics of the tumors. We used RT-PCR, in situ hybridization and immunohistochemistry to detect trypsinogen- and TATI mRNA and protein in tissue samples from 28 bladder cancer patients and ten benign urothelia. TATI expression was detected in all benign tissues and non-invasive tumors. However, the expression was lower in the muscle-invasive tumors (pT2; n=5), whereas trypsinogen expression was seen in all but one non-invasive tumor. We conclude that trypsinogen is expressed in both malignant and benign bladder epithelium, whereas TATI expression decreases with increasing stage and grade of the tumor. This may suggest that a balanced expression of TATI and trypsinogen is required in normal tissue and that this balance is disrupted during tumor progression.

High tissue expression of tumour-associated trypsin inhibitor (TATI) associates with a more favourable prognosis in gastric cancer

AIMS

The tumour-associated trypsin inhibitor (TATI) is a 6-kDa protease inhibitor with potential inhibitory effects on tissue degradation. In serum, increased levels have been associated with adverse prognosis in different forms of cancer. We assessed the tumour tissue expression and prognostic value of TATI in a surgically treated, single-institution series of patients with gastric cancer.

METHODS AND RESULTS

Using a monoclonal anti-TATI antibody, immunohistochemistry was performed on formalin-fixed paraffin-embedded tumour specimens from 336 patients. TATI expression was observed in 265 (79%) of the tumours. There was a significant association between high TATI expression and low stage (P = 0.007), superficial tumours (P = 0.005), and absence of nodal (P = 0.015) and of distant metastases (P = 0.022). In univariate analysis, patients with high TATI expression had a significantly more favourable 5-year cumulative survival compared with patients with negative to moderate immunostaining (43% and 28%, respectively, P = 0.006). On multivariate survival analysis stratified for estimated cure of surgery, stage (P < 0.0001) and age (P = 0.022) at the time of surgery were independent prognostic factors.

CONCLUSIONS

High TATI expression in tumour tissue was detected more frequently in patients with early-stage gastric cancer and seems to correlate with a favourable outcome.

Co-expression of trypsin and tumour-associated trypsin inhibitor (TATI) in colorectal adenocarcinomas

Trypsin and its specific inhibitor, TATI (tumour-associated trypsin inhibitor), are expressed in normal human pancreas and in a variety of tumours. The aim of the present study was to assess the parallel expression of trypsin and TATI in colorectal cancer, in comparison with their expression in normal epithelial tissue, since proteases and their inhibitors are thought to be co-expressed in malignant neoplasms. We also assessed the possible significance of their expression as a means of differentiation between normal and malignant tissue. We examined qualitatively and semi-quantitatively the immunohistochemical expression of trypsin and TATI on paraffin-embedded serial tissue sections from 91 colorectal adenocarcinomas. The reverse-transcriptase-polymerase-chain reaction (RT-PCR) was also performed on fresh malignant tissue from 55 of the above adenocarcinomas. Normal and non-malignant tissues adjacent to the tumours were also evaluated. Cytoplasmic expression of trypsin (more than 25% of the cancer cells positive) was found in 67 (73.6%) adenocarcinomas, whereas TATI was expressed in the cytoplasm of 59 (64.8%) cases studied. Statistical analysis using Spearman's test has demonstrated a significant correlation between trypsin and TATI immunohistochemical expression (p<0.01). RT-PCR showed co-expression of trypsin and TATI mRNA in all carcinomas studied. Distinct patterns of trypsin and TATI immunohistochemical expression were observed in adjacent, non-malignant tissues, where both trypsin and TATI mRNA were also detected. Normal tissues were negative by immunohistochemistry. Our results indicate co-expression of trypsin and TATI in colorectal tumours both at the mRNA and protein level. We conclude that in colorectal neoplasms, high levels of trypsin and TATI may be important for malignant tumour formation and/or metastatic process.

Tumor-associated trypsin inhibitor in normal and malignant renal tissue and in serum of renal-cell carcinoma patients

Tumor-associated trypsin inhibitor (TATI) is a 6-kDa peptide, which is identical to the pancreatic-secretory-trypsin inhibitor (PSTI). TATI is produced by several tumors and cancer cell lines, and is used as a serum marker for mucinous ovarian cancer. Elevated serum levels of TATI have also been observed in renal-cell carcinoma (RCC). However, it is unclear whether the increase of serum TATI in this disease is caused by production of TATI by the tumor tissue, by the acute-phase reaction frequently associated with cancer, or by impaired renal function. We examined the expression of TATI in malignant and histologically normal renal tissue by immunohistochemistry, in situ hybridization and reverse-transcriptase-polymerase-chain reaction (RT-PCR). Furthermore, we measured pre-operative serum TATI levels in 21 patients with RCC. Immunohistochemically, TATI was detected in 13 of 20 histologically normal renal-tissue samples, but not in 32 tissue samples from RCC. By RT-PCR, TATI mRNA was detected in all of 10 histologically normal kidneys and in 6 of 11 RCCs, while in situ hybridization analysis gave negative results. Pre-operative serum TATI was elevated in 57% of RCC patients. We also studied expression of TATI mRNA and protein in 7 renal-cancer cell lines, by RT-PCR and immunofluorometric assay respectively: 6 cancer cell lines were positive for TATI mRNA, while 4 of them also produced TATI protein at low levels. These results indicate that TATI is synthesized by the histologically normal renal tissue and by some renal cancers, and suggest that the elevation of serum TATI associated with renal-cell carcinoma may be caused by the release of TATI produced by the tumor.

Identification of novel pancreas-specific regulatory sequences in the promoter region of human pancreatic secretory trypsin inhibitor gene

The human pancreatic secretory trypsin inhibitor (PSTI) genes introduced into mice are specifically expressed in pancreas. The 1.0 kilobase pairs of PSTI 5'-flanking sequence directed preferential expression of a linked reporter chloramphenicol acetyltransferase, which was active in a PSTI-expressing pancreatic cell line (AR42j) but not in a PSTI-nonexpressing fibroblast cell line (XC). Two positively acting elements were found, Region I (-161/-116) and Region II (-103/-74), as defined by transfection and binding assays with AR42j cells. Region II is sufficient for the pancreas-specific expression, but the presence of both Regions I and II is needed for the maximum activity. Sequence studies also revealed that these two elements differ from the previously identified recognition sequence for pancreas transcription factor 1 (PTF1). When the same set of experiments was done with XC cells, one negatively acting element was identified, Region IV (-154/-137). Interestingly, Regions I and IV share a core sequence (-149/-139), CAATCAATAAC. These results suggest that this novel element regulates the human PSTI gene expression positively in pancreatic cells but negatively in nonpancreatic cells.

Characterization of engineered hepatitis C virus NS3 protease inhibitors affinity selected from human pancreatic secretory trypsin inhibitor and minibody repertoires

Given the extent of hepatitis C virus (HCV) infection as a worldwide health problem and the lack of effective treatment, the development of anti-HCV drugs is an important and pressing objective. Previous studies have indicated that proteolytic events mediated by the NS3 protease of HCV are fundamental to the generation of an active viral replication apparatus, as unequivocably demonstrated for flaviviruses. As a result, the NS3 protease has become a major target for discovering anti-HCV drugs. To gain further insight into the biochemical and biophysical properties of the NS3 enzyme binding pocket(s) and to generate biological tools for developing antiviral strategies, we decided to engineer macromolecular ligands of the NS3 protease domain. Phage-displayed repertoires of minibodies ("minimized" antibody-like proteins) and human pancreatic secretory trypsin inhibitor were sampled by using the recombinant NS3 protease domain as a ligate molecule. Two protease inhibitors were identified and characterized biochemically. These inhibitors show marked specificity for the viral protease and potency in the micromolar range but display different mechanisms of inhibition. The implications for prospective development of low-molecular-weight inhibitors of this enzyme are discussed.

Production and secretion of pancreatic secretory trypsin inhibitor in normal human small intestine

The aim of this study was to prove the production and secretion of pancreatic secretory trypsin inhibitor (PSTI) in human small intestine. To achieve this we analyzed the content of immunoreactive PSTI (irPSTI) in rinsing fluid from isolated small intestine, using the urea method to estimate the volume of epithelial lining fluid recovered. IrPSTI, measured by an enzyme-linked, immunosorbent assay (ELISA), was present in both free and complexed form. The free PSTI showed intact biologic activity, binding trypsin in stable complexes. The complexed PSTI was dissociated on acidification. With the reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot hybridization, PSTI mRNA was demonstrated in the mucosa of the ileum. These findings indicate that PSTI is produced and secreted in the small intestinal epithelium and may be part of defence system in intestinal mucosa.

An integrating vector for tunable, high copy, stable integration into the dispersed Ty delta sites of Saccharomyces cerevisiae

We have constructed a yeast integration vector targeted to chromosomal Ty delta sequences and used it to create Saccharomyces cerevisiae strains with stable tandem integrations ranging from 1 to 30 vector copies. The vector carries the bacterial NEO gene, allowing copy number to be tuned by varying G418 resistance, which generally increases with copy number as determined by quantitative Southern blot. Tandem integration into a single site is most commonly observed, but single-copy and two-site integration is also observed. Bovine pancreatic trypsin inhibitor was constitutively expressed and secreted using the NEO-based delta vector, and secretion levels were 2-10-fold improved relative to commonly used 2 mu multicopy yeast plasmids. The NEO-based Ty delta vector is a powerful tool for stable heterologous protein expression and secretion in yeast.

Production of bovine-pancreatic-trypsin-inhibitor homologues in Escherichia coli and their characterization

Biologically active bovine pancreatic trypsin inhibitor (BPTI) was produced in Escherichia coli using an OmpA leader-peptide fusion-protein system, and BPTI homologues were generated by cassette mutagenesis. Amino acids in the reactive loop of alpha 1-proteinase inhibitor (alpha 1-PI) were incorporated into the reactive loop of BPTI in a stepwise approach such that the contribution of individual amino acids could be assessed. The introduction of mutations into BPTI diminished the yield of heterologous protein relative to wild-type BPTI. However, for three BPTI homologues sufficient material was isolated to allow characterization of the proteins by electrospray MS and N-terminal peptide sequencing.

A human pancreatic secretory trypsin inhibitor presenting a hypervariable highly constrained epitope via monovalent phagemid display

Hypervariable gene banks displaying ligands which can be used for affinity optimisation are valuable resources for examining shape space. They have added value if the ligand is small, if there is extensive information on its tertiary structure and if the variable region is highly constrained. These features would be expected to stabilise complexes by reducing the dissociation constants and to facilitate their use as 'lead substances' for the development of synthetic mimetics. The synthesis and characterisation of such phagemid-display banks is described here, in which the variable region is a 7-amino acid (aa) (pSKAN8-HyB/C) or 8-aa (pSKAN8-HyA) extended peptide held between two disulfide bridges at the exposed tip of the human pancreatic secretory trypsin inhibitor (PSTI). A phagemid pSKAN8 was created which contains a fusion between the PSTI and M13 pIII protein-coding genes. Cassettes containing the sequences (NNK)8 [HyA], (NNK)7 [HyB] or (NNK)6GTT [Hy-C] (where K = G or T) were used to randomize the aa coding region in the trypsin-inhibitory loop (aa 17 to 23) of PSTI. Some 31 million individual clones were generated in a mutS Escherichia coli strain kept as frozen cell stocks. Analysis of controls which had not undergone selection showed very low levels of deletion. The quality of the hypervariable region and bias of codon usage was quantified by DNA sequencing. It was estimated from SDS-PAGE that hybrid protein was represented statistically at a frequency of one molecule per two phagemid particles. The functionality and reproducibility of the system was demonstrated by trypsin-binding of the original vector and in selecting novel chymotrypsin inhibitors from the banks.

Pancreatic secretory trypsin inhibitor gene is highly expressed in the liver of adult-onset type II citrullinemia

Deficiency of argininosuccinate synthetase (ASS) causes citrullinemia. Type II citrullinemia is found in most patients with adult-onset citrullinemia in Japan, and ASS is deficient specifically in the liver. Previous studies have shown that the decrease of hepatic ASS activity is caused by a decrease in enzyme protein with normal kinetic properties and that there are no apparent abnormalities in the amount, translational activity, and nucleotide sequence of hepatic ASS mRNA. Recent results of homozygosity testing indicate that the primary defect of type II citrullinemia is not within the ASS gene locus. In this present work, to understand the pathogenesis and pathophysiology of type II citrullinemia, we have characterized the alterations of gene expression in the liver of type II patients using the recently developed mRNA differential display method. Some cDNA bands expressed differently in type II citrullinemia patients and control were selected, cloned, and sequenced. Nucleotide sequence analysis and homology searching revealed an interesting clone which has 99% homology with the human pancreatic secretory trypsin inhibitor (hPSTI). Northern blot and RT-PCR analyses showed that the expression of hPSTI mRNA increased significantly in the liver of all type II patients tested. Furthermore, the concentration of hPSTI protein was found to be higher in the liver of type II citrullinemia than in control. These results suggest that hPSTI may be related to the primary defect of type II citrullinemia and may be useful as a diagnostic marker, although the detailed mechanism of the high expression of hPSTI mRNA in type II liver is not yet known.

Response to IL-6 stimulation of human hepatoblastoma cells: production of pancreatic secretory trypsin inhibitor

LPS-stimulated macrophage conditioned medium and IL-6 markedly stimulated the secretion of PSTI by cultured hepatoblastoma cells. The mechanism underlying the cellular response of IL-6-induced secretion of PSTI was investigated. Among the agents affecting the signal transduction pathways, forskolin significantly induced PSTI secretion whereas PMA or A23187 did not, suggesting that IL-6 induced PSTI secretion is mediated by cAMP dependent protein kinase A.

Production of recombinant human pancreatic secretory trypsin inhibitor by Escherichia coli

A synthetic gene for human pancreatic secretory trypsin inhibitor (PSTI) was fused to the coding sequence for the amino-terminal 135 amino acid residues of human interferon-gamma (IFN-gamma) by interposing a methionine codon sequence, and the resulting hybrid gene was efficiently expressed in Escherichia coli cells. Recombinant human PSTI (rHu-PSTI) was separated from the IFN-gamma/PSTI fused protein by cleavage at the methionine residue with cyanogen bromide. Finally, rHu-PSTI was purified by affinity chromatography on a bovine trypsin-CH-Sepharose 4B column. The amino acid composition, partial amino-terminal sequence, disulfide formation, human trypsin inhibitory activity, and immunoreactivity against rabbit anti-human PSTI serum of rHu-PSTI corresponded to those of the natural form.

Pancreatic secretory trypsin inhibitor-like immunoreactivity in pancreatectomized patients

Pancreatic secretory trypsin inhibitor (PSTI) is a 6000-dalton peptide, that occurs in high concentrations in the pancreas and in pancreatic juice. It is thought to be synthesized by pancreatic acinar cells. We have recently reported the findings of an identical trypsin inhibitor at high concentrations in the urine of patients with gynecological malignancy. Therefore, we have named the inhibitor tumor-associated trypsin inhibitor (TATI). We have now studied patients who have undergone total pancreatoduodenectomy for pancreatic cancer or chronic pancreatitis. By radioimmunoassay (RIA), we found normal levels of this inhibitor in the serum and urine of pancreatectomized patients. The absence of pancreas was confirmed by measuring serum trypsin. By gel filtration and HPLC it was found that PSTI/TATI occurring in pancreatectomized patients was indistinguishable from that found in connection with pancreatitis and ovarian cancer.