Pancreatic cancer: the role of cholecystokinin?

Risk of cancer in patients with cholecystitis: a nationwide population-based study

OBJECTIVE

The objective of this study was to evaluate the risk of cancer in patients diagnosed with cholecystitis and possible interactions between cholecystitis and cholecystectomy.

METHODS

A retrospective population-based cohort study was conducted among patients diagnosed with cholecystitis that were registered in the National Health Insurance Research Database in Taiwan between January 1, 2000 and December 31, 2010. Standardized incidence ratios (SIRs) were calculated to compare the incidence of cancer in these patients to that of the general population. Adjusted hazard ratios (HRs) were also calculated to investigate whether cholecystitis increased the risk for specific cancers.

RESULTS

During a median observation period of 5.4 years, 1541 cancers occurred in 20,431 patients with cholecystitis, yielding a SIR of 1.97 (95% confidence interval [CI], 1.88-2.07). A significantly greater risk of biliary tract cancer (adjusted HR 1.72; 95% CI, 1.08-2.75) was observed after adjusting for potential risk factors. In contrast, cholecystectomy was found to attenuate the cancer risk, with the reduction of adjusted HR from 2.34 (95% CI, 1.62-3.37) to 1.28 (95% CI, 0.76-2.14).

CONCLUSION

Cholecystitis is an independent risk factor to extrahepatic biliary tract cancers, whereas cholecystectomy can attenuate the cancer risk of cholecystitis.

Gallstones, a cholecystectomy, chronic pancreatitis, and the risk of subsequent pancreatic cancer in diabetic patients: a population-based cohort study

BACKGROUND

The causal association between diabetes and pancreatic cancer remains unclear in Asian populations. This study examined whether gallstones, a cholecystectomy, chronic pancreatitis and the treatment of antidiabetic agents affect the risk of subsequent pancreatic cancer for patients with diabetes in a Taiwanese population.

METHODS

Using claims data from the universal health insurance program in Taiwan, 449,685 newly diagnosed diabetic cases among insured people from 2000 to 2003 were identified as the case group. The comparison group, matched for gender, age, and the index year of the diabetes cohort, consisted of 325,729 persons without diabetes. Pancreatic cancer incidence was measured in both groups until the end of 2008. Other risk factors associated with this cancer were also measured.

RESULTS

The incidence of pancreatic cancer in the diabetic cohort was 2-fold greater than that in the comparison group (1.46 vs. 0.71 per 10,000 person-years) with an adjusted hazard ratio (HR) of 1.75 [95 % confidence interval (CI) 1.45-2.10]. The risk slightly increased for diabetic patients with gallstones, cholecystitis, and a cholecystectomy (HR 1.92, 95% CI 1.18-3.11), but greatly increased for those with comorbidity of chronic pancreatitis (HR 22.9, 95% CI 12.6-41.4). Pancreatic cancer risk also increased significantly for those patients who used more insulin for treating diabetes (OR 2.20, 95% CI 1.40-3.45).

CONCLUSION

Our data suggest that the risk of pancreatic cancer is moderately increased in patients with diabetes, especially those using insulin therapy. The risk is greatly increased for diabetic patients with chronic pancreatitis.

Genetic analysis of pancreatic duct hyperplasia in Otsuka Long-Evans Tokushima Fatty rats: possible association with a region on rat chromosome 14 that includes the disrupted cholecystokinin-A receptor gene

An Otsuka Long-Evans Tokushima Fatty (OLETF) strain of rat spontaneously developed hyperglycemia, hyperinsulinemia, insulin resistance and mild obesity, which had been studied as animal model for type II diabetes mellitus (T2DM). Recently, we observed that this strain coincidentally developed atypical hyperplasia of the choledocho-pancreatic ductal epithelium with a complete incidence. In an effort to locate genes responsible for this hyperplasia, we prepared 288 backcross progeny from a mating between OLETF rats and BN rats (which do not develop hyperplasia), and performed a genome-wide scan using 207 polymorphic genetic markers. We observed a prominent association of hyperplasia with a region involving a marker locus D14Mit4 (P = 0.00020, Fisher's exact test) and Cckar (the cholecystokinin-A receptor gene; P = 0.00025, Fisher's exact test) which is known to be disrupted in an OLETF strain. Our findings indicated that epithelial hyperplasia of the choledocho-pancreatic duct is associated with a region on rat chromosome 14 around the Cckar gene in an additive fashion with another two susceptible loci, each on chromosome 9 and 7. This implied the possibility that Cckar deficiency could result in a predisposition towards pancreatic duct hyperplasia.

Closing the gastrin loop in pancreatic carcinoma: coexpression of gastrin and its receptor in solid human pancreatic adenocarcinoma

BACKGROUND

Alpha-amidated gastrin promotes the growth of nontransfected pancreatic cell lines expressing the gastrin/cholecystokinin (CCK)-B receptor. Gastrin/CCK-B and CCK-A receptors recently were demonstrated in human pancreatic adenocarcinomas, but to the authors' knowledge expression of their ligands to date have not been adequately investigated. As a prerequisite for making suggestions regarding local growth stimulation, the authors examined whether gastrin and the homologous CCK peptides as well as their specific receptors were expressed in consecutively collected solid human pancreatic adenocarcinomas.

METHODS

Using a library of radioimmunoassays specific for different epitopes on proCCK, progastrin, their processing intermediates, and bioactive end products, CCK and gastrin gene expression was measured in extracts of solid human pancreatic adenocarcinomas (n = 19), resection margins (n = 15), and normal pancreatic tissue (n = 8). Moreover, CCK, CCK-A receptor, and gastrin/CCK-B receptor mRNA were measured by reverse transcriptase-polymerase chain reaction.

RESULTS

Amidated gastrins were synthetized in 14 of 19 carcinomas (median, 0.4 pmol/g; range, < 0.1-84.0 pmol/g) and in 12 of 15 resection margin samples (median, 0.3 pmol/g; range, < 0.1-6.1 pmol/g). In contrast, normal human pancreatic tissue expressed only traces of poorly processed progastrin. Gastrin/CCK-B receptor mRNA was present in all carcinomas, resection margins, and normal pancreatic tissue. CCK-A receptor mRNA was detected in most tumors, but neither the mature ligands (alpha-amidated and O-sulfated CCK peptides) nor their precursors were expressed in carcinoma and normal pancreatic tissue.

CONCLUSIONS

The results of the current study demonstrate that alpha-amidated gastrin peptides and their receptor invariably are coexpressed in pancreatic adenocarcinoma. Therefore these findings support the contention of a role for local gastrin regulatory mechanisms, but no CCK mechanisms, in pancreatic carcinoma.

The effect of intermittent injections of CCK-8S and the CCK-A receptor antagonist devazepide on cell proliferation in exocrine rat pancreas

CONCLUSION

Intermittent injections of sulfated cholecystokinin-8 (CCK-8S) or devazepide caused long-lasting effects on cell proliferation in exocrine pancreas in contrast to continuous infusion. The acinar cells responded to both treatments with changes in the labeling index (LI) during the whole study period. When studying the influence of stimulation and inhibition of the CCK-A receptor on cell proliferation in the exocrine pancreas, not only are the drugs and doses of importance but also the mode of administration.

BACKGROUND

Continuous infusion of CCK-8S or the CCK-A receptor antagonist devazepide induces transient changes in acinar cell proliferation in rat pancreas. The aim of the present experiments was to study whether intermittent administration of CCK-8S or devazepide prevents receptor desensitization and thereby affects exocrine pancreatic cell proliferation persistently.

METHODS

Male Sprague-Dawley rats were injected subcutaneously twice daily with CCK-8S (6 micrograms), devazepide (240 micrograms) or bovine serum albumin (BSA). The rats were sacrificed after 18 and 36 h and 3 and 7 d. One hour before sacrifice, the rats were injected intraperitoneally with 1 mCi/kg of tritiated thymidine. The pancreatic weight and the contents of water, protein, and DNA were determined. The LI (number of labeled cells/100 cells) of exocrine pancreatic cells was determined microscopically after autoradiography.

RESULTS

The concentration of plasma CCK was slightly increased by devazepide, but the increase was more pronounced by CCK-8S. The pancreatic wet weight was transiently increased 18 h after the start of CCK-8S injections (+14%), whereas devazepide caused a reduction after 7 d (-22%). The protein content was uninfluenced and the DNA content was decreased at 36 h with either treatment. CCK-8S increased the LI in acinar and centroacinar cells throughout the study period, but the ductal cell LI was increased only after 18 and 36 h. Injection of devazepide was followed by decreased LI of acinar cells throughout the study period. Also, the centroacinar and ductal cell LI decreased initially but returned to control values after 7 d.

Biology of gut cholecystokinin and gastrin receptors

1. The stomach hormone gastrin and the intestinal hormone cholecystokinin (CCK) share a common C-terminal pentapeptide sequence but have different biological roles. Gastrin is the major stimulant of gastric acid secretion and has a growth stimulatory effect on the secretory part of the stomach. The physiological roles of CCK are the stimulation of pancreatic secretion and the contraction of the gall-bladder. 2. Several classes of receptors have been defined for peptides of the gastrin/CCK family. The CCKA receptor on pancreatic acini has a greater affinity for sulfated CCK than for gastrin, while the gastrin/CCKB receptor in gastric mucosa and brain has similar affinities for both gastrin and CCK. Potent and selective antagonists have been developed for both receptor classes. 3. The structures of the CCKA and gastrin/CCKB receptors have been deduced from the nucleotide sequences of cloned cDNA. The receptors, which both belong to the family with seven transmembrane segments, control secretion via similar signalling mechanisms. Occupation of either receptor leads to activation of phospholipase C, with resultant increases in intracellular levels of inositol triphosphate and Ca2+. Mitogenic signalling pathways are also being defined. 4. Recent studies have questioned the previous assumption that gastrin precursors are inactive. Glycine-extended gastrin17 has been shown to stimulate mitogenesis in some cell lines and may also have an autocrine role in the growth of colonic cancers. The receptors involved, which are clearly distinct in binding properties from the CCKA and gastrin/CCKB receptors, have not yet been cloned. Specific antagonists for the novel receptors will be required to define their function in further detail.

The role of gastrin and cholecystokinin in normal and neoplastic gastrointestinal growth

Gastrin and cholecystokinin (CCK) act as growth factors for the gastric mucosa and the pancreas, respectively. CCK is also responsible, via the CCK-A receptor, for the pancreatic hyperplasia observed following the feeding of protease inhibitors or pancreaticobiliary diversion. Hypergastrinaemia does not increase the incidence of spontaneous gastrointestinal carcinoma, but does stimulate the proliferation of gastric enterochromaffin-like cells via the gastrin/CCK-B receptor, with a consequent increase in the incidence of gastric carcinoids. Whether gastrin influences mutagen-induced gastrointestinal carcinogenesis is still controversial, but CCK clearly enhances the induction by carcinogens of acinar tumours in the pancreas. While gastrin increases xenograft growth of 50% of gastrointestinal tumours tested, effects on the proliferation of gastrointestinal tumour cell lines in vitro have been more difficult to demonstrate, perhaps because many cell lines are already maximally stimulated by autocrine gastrin. Gastrin mRNA and progastrin, but not mature amidated gastrin, have been detected in all gastrointestinal cell lines tested. Although cell proliferation is inhibited by gastrin/CCK receptor antagonists, the spectrum of antagonist affinities is not consistent with binding to either CCK-A or gastrin/CCK-B receptors. Definition of the molecular structure of the receptor involved in the autocrine loop may lead to novel therapies for gastrointestinal cancer.

Effect of cholecystokinin analogue caerulein and cholecystokinin antagonist lorglumide on pancreatic carcinogenesis in the rat

The effects of the cholecystokinin (CCK)-analogue, caerulein, and CCK-receptor antagonist lorglumide (CR-1409) on pancreatic carcinogenesis induced by 7,12-dimethylbenz(a)anthracene (DMBA) were studied. One hundred thirty rats were divided into the following 10 treatment groups: group 1, DMBA (2-3 mg); group 2, DMBA + caerulein (5 micrograms/kg); group 3, DMBA + caerulein + CR-1409 (12 mg/kg); group 4, caerulein + DMBA; group 5, caerulein + CR-1409 + DMBA; group 6, DMBA + CR-1409; group 7, CR-1409 + DMBA; group 8, caerulein; group 9, CR-1409; and group 10, sham operation + saline. DMBA was surgically implanted into the pancreas. Caerulein and/or CR-1409 was administered twice daily for 15 days after (in groups 2, 3, and 6) or before (in groups 4, 5, and 7) DMBA implantation. Six months after carcinogen administration, all rats were sacrificed and autopsied. The incidence of pancreatic cancer appeared significantly (P < 0.001) increased when caerulein was administered following DMBA implantation. CR-1409 significantly inhibited (P < 0.02) caerulein effects and reduced tumor growth when injected after carcinogen exposure.