Assessment of Precision Irradiation in Early Non-Small Cell Lung Cancer and Interstitial Lung Disease (ASPIRE-ILD): Primary Analysis of a Phase II Trial

PURPOSE/OBJECTIVE(S)

The use of stereotactic ablative radiotherapy (SABR) in patients with fibrotic interstitial lung disease (ILD) has been associated with an increased risk of toxicity, but patients with ILD and lung cancer may have no other options for curative-intent treatment. The goal of the ASPIRE-ILD trial was to assess the benefits and toxicities of SABR in patients with fibrotic ILD.

MATERIALS/METHODS

We enrolled patients with fibrotic ILD and a diagnosis of T1-2N0 NSCLC who were not candidates for surgery. All patients were centrally reviewed prior to enrollment to confirm the presence and subtype of ILD. After stratification by the ILD-GAP score (a measure of ILD severity and prognosis), patients were treated with SABR to a dose of 50 Gy in 5 fractions EOD (BED = 100 Gy10), with a built-in de-escalation protocol in case of unacceptable toxicity. The primary endpoint was overall survival (OS), powered to distinguish 1-year OS >70% vs. an unacceptable rate of ≤50%. Secondary endpoints included toxicity (CTC-AE version 4.0), progression-free survival (PFS), local control (LC), patient-reported outcomes (FACT-L quality of life and cough severity), and changes in pulmonary function tests (PFTs). The study pre-specified that SABR would be considered worthwhile if median OS was >1 year, with a grade 3-4 toxicity risk <35% and a grade 5 toxicity risk <15%. Target accrual was 39 treated patients.

RESULTS

Thirty-nine patients were enrolled and treated with SABR between March 2019 and January 2022, all to a dose of 50 Gy in 5 fractions, at 5 institutions in Canada and 1 in Scotland. Median age was 78 years (interquartile range: 67-83), 59% were male, and 92% had a history of smoking (median 43 pack-years). At baseline, 70% reported dyspnea, median FEV1 was 80% predicted and median DLCO was 49% predicted. ILD-GAP scores were as follows: ≤2 (i.e., best ILD status): n = 14; 3-5: n = 23; ≥6 (i.e., worst ILD status): n = 2. Median follow-up was 19 months. OS at 1-year was 78.9% (p<0.001 by binomial test vs. the unacceptable rate). Median OS was 25 months, median PFS was 19 months, and 2-year LC was 92%. AE rates (possibly, probably or definitely related) were as follows (highest grade per patient): grade 1-2: n = 12 (31%); grade 3: n = 4 (10%); grade 4; n = 0; grade 5 n = 3 (7.7%, all due to respiratory deterioration). AE rates did not differ by ILD-GAP category or ILD subtype. FACT-L scores trended downward over time (p = 0.07), and cough severity scale scores worsened over time (p = 0.02). Comparing last-available PFTs with baseline, DLCO declined (median: -4%; p = 0.046), FVC trended downward (median: -2.5%; p = 0.11), and FEV1 remained stable (median change: 0%).

CONCLUSION

The use of SABR in patients with ILD met the pre-specified acceptability thresholds for both toxicity and efficacy, supporting the use of SABR for curative-intent treatment after a careful discussion of risks and benefits. Further studies exploring pharmacologic options to reduce toxicity may be beneficial in this population. ().

The early story of growth hormone-releasing factor in rats, swine, and cattle

Following the discovery of the growth hormone-releasing factor from a human pancreatic tumor by the group of Guillemin at the Salk Institute in California, research on this factor has exploded. This review article is focused on the results obtained early after this discovery and summarizes the biological effects of this releasing factor on the rat digestive system development and above all on pig, steer, and gilt growth as well as on milk production in lactating sows and cows.

Life with the pancreas: A personal experience

This review article has primary objective to summarize pancreatic research which has been done in our laboratory since 1965, the first year of the author's registration in the Ph.D. program at the University of Sherbrooke (Canada). It covers the following major topics of pancreatic physiology: controls of pancreatic adaptation to diet, control of pancreatic enzyme secretion, control of pancreatic enzyme synthesis, control of pancreatic growth, intracellular events stimulated during pancreatic growth, pancreas regeneration after pancreatitis and pancreatectomy, the pancreatic cholecystokinin receptor types 1 and 2, growth control and cell signaling in pancreatic cancer cells and finally, cystic fibrosis.

Baseline characteristics and comorbidities in the CAnadian REgistry for Pulmonary Fibrosis

Background

The CAnadian REgistry for Pulmonary Fibrosis (CARE-PF) is a multi-center, prospective registry designed to study the natural history of fibrotic interstitial lung disease (ILD) in adults. The aim of this cross-sectional sub-study was to describe the baseline characteristics, risk factors, and comorbidities of patients enrolled in CARE-PF to date.

Methods

Patients completed study questionnaires and clinical measurements at enrollment and each follow-up visit. Environmental exposures were assessed by patient self-report and comorbidities by the Charlson Comorbidity Index (CCI). Baseline characteristics, exposures, and comorbidities were described for the overall study population and for incident cases, and were compared across ILD subtypes.

Results

The full cohort included 1285 patients with ILD (961 incident cases (74.8%)). Diagnoses included connective tissue disease-associated ILD (33.3%), idiopathic pulmonary fibrosis (IPF) (24.7%), unclassifiable ILD (22.3%), chronic hypersensitivity pneumonitis (HP) (7.5%), sarcoidosis (3.2%), non-IPF idiopathic interstitial pneumonias (3.0%, including idiopathic nonspecific interstitial pneumonia (NSIP) in 0.9%), and other ILDs (6.0%). Patient-reported exposures were most frequent amongst chronic HP, but common across all ILD subtypes. The CCI was ≤2 in 81% of patients, with a narrow distribution and range of values.

Conclusions

CTD-ILD, IPF, and unclassifiable ILD made up 80% of ILD diagnoses at ILD referral centers in Canada, while idiopathic NSIP was rare when adhering to recommended diagnostic criteria. CCI had a very narrow distribution across our cohort suggesting it may be a poor discriminator in assessing the impact of comorbidities on patients with ILD.

Somatostatin: One of the Rare Multifunctional Inhibitors of Mammalian Species

This review article has for major main objectives to give an overlook of the major physiological effects of somatostatin on different organs. It will cover first the general aspect of the hormone, its cDNA and its protein maturation process, as well as its characterization in various organs. This aspect will be followed by the factors involved in the control of its secretion, its intracellular mode of action, and its general action on physiological processes. Secondly, the review will focus on the pancreas, looking at its in vivo and in vitro actions with special attention on its effects on normal pancreas growth and pancreatic tumors.

Is there adaptation of the exocrine pancreas in wild animal? The case of the Roe deer

Background

Physiology of the exocrine pancreas has been well studied in domestic and in laboratory animals as well as in humans. However, it remains quite unknown in wildlife mammals. Roe deer and cattle (including calf) belong to different families but have a common ancestor. This work aimed to evaluate in the Roe deer, the adaptation to diet of the exocrine pancreatic functions and regulations related to animal evolution and domestication.

Results

Forty bovine were distributed into 2 groups of animals either fed exclusively with a milk formula (monogastric) or fed a dry feed which allowed for rumen function to develop, they were slaughtered at 150 days of age. The 35 Roe deer were wild animals living in the temperate broadleaf and mixed forests, shot during the hunting season and classified in two groups adult and young. Immediately after death, the pancreas was removed for tissue sample collection and then analyzed. When expressed in relation to body weight, pancreas, pancreatic protein weights and enzyme activities measured were higher in Roe deer than in calf. The 1^st original feature is that in Roe deer, the very high content in pancreatic enzymes seems to be related to specific digestive products observed (proline-rich proteins largely secreted in saliva) which bind tannins, reducing their deleterious effects on protein digestion. The high chymotrypsin and elastase II quantities could allow recycling of proline-rich proteins. In contrast, domestication and rearing cattle resulted in simplified diet with well digestible components. The 2^nd feature is that in wild animal, both receptor subtypes of the CCK/gastrin family peptides were present in the pancreas as in calf, although CCK-2 receptor subtype was previously identified in higher mammals.

Conclusions

Bovine species could have lost some digestive capabilities (no ingestion of great amounts of tannin-rich plants, capabilities to secrete high amounts of proline-rich proteins) compared with Roe deer species. CCK and gastrin could play an important role in the regulation of pancreatic secretion in Roe deer as in calf. This work, to the best of our knowledge is the first study which compared the Roe deer adaptation to diet with a domesticated animal largely studied.

Epithelial BMP signaling is required for proper specification of epithelial cell lineages and gastric endocrine cells

Bone morphogenetic protein (BMP) signaling within the gastrointestinal tract is complex. BMP ligands and their receptors are expressed in both epithelial and mesenchymal compartments, suggesting bidirectional signaling between these two entities. Despite an increasing interest in BMP signaling in gut physiology and pathologies, the distinct contribution of BMP signaling in the epithelium vs. the mesenchyme in gastrointestinal homeostasis remains to be established. We aimed to investigate the role of epithelial BMP signaling in gastric organogenesis, gland morphogenesis, and maintenance of epithelial cell functions. Using the Cre/loxP system, we generated a mouse model with an early deletion during development of BMP receptor 1A (Bmpr1a) exclusively in the foregut endoderm. Bmpr1a(ΔGEC) mice showed no severe abnormalities in gastric organogenesis, gland epithelial proliferation, or morphogenesis, suggesting only a minor role for epithelial BMP signaling in these processes. However, early loss of BMP signaling in foregut endoderm did impact on gastric patterning, leading to an anteriorization of the stomach. In addition, numbers of parietal cells were reduced in Bmpr1a(ΔGEC) mice. Epithelial BMP deletion significantly increased the numbers of chromogranin A-, ghrelin-, somatostatin-, gastrin-, and serotonin-expressing gastric endocrine cells. Cancer never developed in young adult (<100 days) Bmpr1a-inactivated mice although a marker of spasmolytic polypeptide-expressing metaplasia was upregulated. Using this model, we have uncovered that BMP signaling negatively regulates the proliferation and commitment of endocrine precursor cells. Our data also indicate that loss of BMP signaling in epithelial gastric cells alone is not sufficient to induce gastric neoplasia.

Cholecystokinin and Somatostatin Negatively Affect Growth of the Somatostatin-RIN-14B Cells

With the exclusive presence of the pancreatic CCK-2 receptors on the pancreatic delta cells of six different species, this study was undertaken to determine the role of cholecystokinin and gastrin on growth of these somatostatin (SS) cells. For this study, the SS-RIN-14B cells were used in culture and their growth was evaluated by cell counting. Results. To our surprise, we established by Western blot that these RIN cells possess the two CCK receptor subtypes, CCK-1 and CCK-2. Occupation of the CCK-1 receptors by caerulein, a CCK analog, led to inhibition of cell proliferation, an effect prevented by a specific CCK-1 receptor antagonist. Occupation of the CCK-2 receptors by the gastrin agonist pentagastrin had no effect on cell growth. Proliferation was not affected by SS released from these cells but was inhibited by exogenous SS. Conclusions. Growth of the SS-RIN-14B cells can be negatively affected by occupation of their CCK-1 receptors and by exogenous somatostatin.

'The most important duty of a mentor remains his availability'. An interview with Dr. Jean Morisset. Interview by Martin E Fernandez-Zapico

We interview Dr. Jean Morisset, an internationally recognized leader in the field of pancreatic physiology. His work on the regulation of pancreatic secretion by hormones and the parasympathetic nervous system has been fundamental to the understanding of pancreatic adaptation to diet in normal as well as pathological conditions. Here he provides advices for young investigators starting in the field of pancreatic research and emphasizes the key role of the relationship mentor-mentee during the career development. and IAP.

The rat pancreatic islets: a reliable tool to study islet responses to cholecystokinin receptor occupation

This study was undertaken to show that rat purified islets can be used as a reliable tool to study some aspects of human islet's physiology related to CCKR occupation. Therefore, isolated foetal, adult human and rat islets were compared for (1) CCKR subtypes mRNA and protein expression and somatostatin (SS) mRNA and (2) co-localization of these receptors with insulin, glucagon and SS. Finally, rat islets were tested for their responsiveness to stimulation. Purified human and rat islets were used for CCKR subtypes and SS mRNA estimation by RT-PCR and protein by Western blots. Receptors and hormones co-localizations were evaluated by confocal microscopy. Hormones secretion served to determine rat islets responsiveness. Islets of both species express CCKA and CCKBR mRNA and proteins and SS mRNA. The CCKAR co-localizes with insulin and glucagon and the CCKBR with SS. Insulin release was increased 5-fold in response to 16 mM glucose and SS secretion reached 1.3- and 1.7-fold increments above basal in response to forskolin and IBMX. In conclusions, human and rat islets have comparable CCKR subtypes localized on the same cells; they also express SS mRNA. The rat islets are functional as they secrete but their response to hormonal stimulation remains to be clarified. These rat islets can thus serve as tools to study islets physiology.

Differential allele-specific accumulation of bovine kappa-casein mRNA throughout lactation

A differential allele-specific accumulation of κ-casein mRNA that is not linked to the κ-casein protein variants is described in Holstein cows. Actually, cows genotyped κ-casein AB were a mixed population. For the first group of κ-casein AB cows, allele A-specific κ-casein mRNA contents within mammary epithelial cells were lower than the allele B-specific ones (cows LH), suggesting that the allele A-specific κ-casein gene was expressed with lower efficiency in mRNA. For the other group of κ-casein AB cows, allele A- and B-specific κ-casein mRNA accumulated to a similar level within mammary epithelial cells (cows HH). The objective of this study was to determine whether the accumulation of allele-specific κ-casein mRNA remained constant throughout lactation for the two groups of cows. Quantitative RT-PCR was used to monitor Holstein cows κ-casein AB genotyped HH and LH throughout lactation for the proportion of allele B-specific mRNA accumulation relative to the total κ-casein encoded mRNA within mammary epithelial cells: RNA was extracted from milk somatic cells known to contain a small proportion of mammary epithelial cells. Mean values of allele B-specific mRNA content were 50·6±0·5 and 54·0±0·9%, for cows HH and cows LH, respectively, and did not vary during lactation (P>0·10). This suggests that the phenotypic expression of the genetic mutation that causes the differential allele-specific accumulation of κ-casein mRNA was not affected by physiological and environmental factors, which tend to vary considerably throughout lactation.

What are the pancreatic target cells for gastrin and its CCKB receptor? Is this a couple for cancerous cells?

The objectives of this review are to summarize, analyse and discuss the roles played by the CCK receptor subtypes and their agonists on pancreatic enzyme secretion, pancreas growth and regeneration, define the receptors specific target cells and evaluate the role of gastrin in pancreatic pathologies including cancer. In rodents, it is clear that the CCKARs present on pancreatic acinar cells play a major role in enzyme secretion. In large mammals, CCK does not seem to be the final mediator of enzyme release. In rat, gastrin and its CCKBR seem responsible for foetal pancreas growth while after birth, CCK was shown to be the most potent trophic factor via occupation of its CCKAR. In pig and human, no one has yet established a direct link between CCK, gastrin and pancreas growth. In rodent's pancreas, the CCKAR were observed on acinar cells as well as on islet's alpha and beta cells; in six other species, the CCKAR were present only on alpha and beta cells with the CCKBR always present on delta cells. The CCKBRs were overexpressed in acute pancreatitis and in metaplastic pancreas following duct ligation. In pancreatic cancer cells, a gastrin autocrine loop involving the CCKBR was suggested. The presence of both CCKR-subtypes and gastrin was observed in many pancreatic tumors; however, their role in cancer growth remains controversial.

Regulation of rat pancreatic CCKB receptor and somatostatin expression by insulin

The cholecystokinin B receptor (CCK(B)R) is localized on pancreatic endocrine somatostatin delta-cells. Pancreatic somatostatin content was increased in diabetic rats. The mechanisms involved in this phenomenon are unknown, and we believe insulin is involved. In this study, four groups of rats were used: controls, streptozotocin-induced diabetic, streptozotocin-induced diabetic with insulin, and streptozotocin-induced diabetic with insulin and its cessation. Rats were killed after 7-28 days of treatment for diabetes, and somatostatin mRNA expression and pancreatic somatostatin content, CCK(B)R mRNA and protein expression evaluation in total pancreas and purified islets, and the cellular localization of somatostatin and CCK(B)R in islets was measured. Data indicate that diabetes is established after 7 days, is controlled by insulin, and reappears after treatment cessation. Pancreatic somatostatin mRNA expression and somatostatin content were increased during diabetes, normalized during insulin treatment, and reaugmented after treatment cessation. Gland and islet CCK(B)R mRNA and protein almost disappeared during diabetes; CCK(B) mRNA reappeared in response to insulin, but the protein did not. Confocal microscopy confirmed data obtained on somatostatin and CCK(B)R as established biochemically in the course of the treatments. In conclusion, these data strongly suggest that insulin can negatively control pancreatic somatostatin mRNA and hormone content and positively control CCK(B)R mRNA; the CCK(B)R protein appears to be delayed.

Induction of tolerance by Porphyromonas gingivalis on APCS: a mechanism implicated in periodontal infection

The periodontal pathogen Porphyromonas gingivalis (Pg) is a potent inducer of the production of pro-inflammatory cytokines by neutrophils, monocytes, and macrophages, and can desensitize immune cells in vitro and in vivo. We analyzed the ability of Pg lipopolysaccharide (LPS) to induce endotoxin tolerance. Treatment of dendritic cells (DC), the human macrophage cell line THP-1, and monocytes (antigen-presenting cells, APC) with Pg.LPS inhibited APC maturation assessed by CD80 and CD86 expression, and inhibited chemokine (CCL3 and CCL5) production. Pre-treatment with glucocorticoids (GC) and interleukin-10 (IL-10) abolished the effect of Pg.LPS on CD80, CD83, and CD86, and on CCL3 and CCL5 production. We also showed that Pg.LPS enhanced the tolerogenic properties of APCs and up-regulated ILT-3 and B7-H1 expression.

Localization of cholecystokinin receptor subtypes in the endocine pancreas

This study was undertaken to clarify the controversy in the literature about pancreatic localization of the cholecystokinin (CCK) CCK(A) and CCK(B) receptors. With antibodies used by other investigators, we first established their specificity by Western blotting, indirect immunofluorescence, and confocal microscopy with each antibody's peptide antigen. Co-localization assays between the CCK receptors and the pancreatic hormones insulin, glucagon, and somatostatin revealed that the CCK(A) RAbs 1122 and R1-2 recognized insulin and glucagon cells in rat, pig, and human pancreas but not in the somatostatin cells. Conversely, the three CCK(B) RAbs tested, 9262, 9491, and GR4, identified the somatostatin cells. Abs 9491 and GR4 occasionally co-localized with glucagon, a feature that never occurred with Ab 9262. Finally, the specificity of Ab 9262 for the pancreatic CCK(B) R was confirmed in six different species. It co-localized with somatostatin but never with glucagon in these species. Our data suggest the use of Abs 1122 and 9262 to specifically identify and localize pancreatic CCK(A) and CCK(B) receptors, respectively. Confusion in the literature may result from the lack of specificity of most antibodies used, as established in this study.

Intervention of GI neuropeptides in pancreatic growth and regeneration: comparison with cholecystokinin

The pancreatic gland has an enormous potential for growth and regeneration, mainly in rodents. These processes remain mostly under the control of the GI hormone cholecystokinin (CCK). The human pancreas however does not show proliferative properties after partial pancreatectomy, but research in this field has been scarce. Recent studies indicate that CCK might not be the expected trophic agent since its two receptors CCK(A) and CCK(B) were not found on human exocrine pancreas. Therefore, if human pancreas grows and regenerates, it has to be under the influence of some unknown trophic factors. Neuropeptides receiving much attention lately as regulators of pancreatic functions could be among the searched trophic agents. This presentation focus on neuropeptides growth potential: GRP-Bombesin, GABA, PP, PYY, Neurotensin, SP, VIP, PACAP, CGRP and galanin. Some neuropeptides have moderate effects on pancreatic enzymes and electrolytes secretion: SP, VIP, PACAP. However, their trophic effects remain unexplored except for GRP-bombesin and PACAP. PACAP preferentially exhibits its mitogenic and proliferative effects on the pancreatic acinar cells AR4-2J via tyrosine kinase, phospholipase D and ornithine decarboxylase activation but not through adenylate cyclase. The growth promoting action of GRP-bombesin is well documented on rodent's pancreas. However, recent studies indicate that this neuropeptide is potentially trophic for larger mammals' pancreas. Indeed, investigators recently documented that bombesin induced pancreatic regeneration in the pig after partial pancreatectomy through mitogen-activated protein kinases activation as do CCK-8 and caerulein on rat pancreas. Have we found the magic pancreatic trophic factor in large mammals? Further investigations will tell.

Convergent alteration of granulopoiesis, chemotactic activity, and neutrophil apoptosis during mouse selection for high acute inflammatory response

Neutrophil homeostasis was investigated in two mouse lines, AIRmax and AIRmin, genetically selected for high or low acute inflammatory response (AIR) and compared with unselected BALB/c mice. Mature neutrophil phenotype and functions appeared similar in the three mouse lines. However, an unprecedented phenotype was revealed in AIRmax animals characterized by a high neutrophil production in bone marrow (BM), a high number of neutrophils in blood, a high concentration of chemotactic agents in acrylamide-induced inflammatory exudates, and an increased resistance of locally infiltrated neutrophils to spontaneous apoptosis. In vitro, BM production of neutrophils and eosinophils was accompanied by an unusual high up-regulation of cytokine receptors as assessed by antibodies to CD131, which bind the common beta chain of receptors to interleukin (IL)-3, IL-5, and granulocyte macrophage-colony stimulating factor. An accelerated neutrophil maturation was also observed in response to all-trans retinoic acid. Several candidate genes can be proposed to explain this phenotype. Yet, more importantly, the results underline that genetic selection, based on the degree of AIR and starting from a founding population resulting from the intercross of eight inbred mouse lines, which display a continuous range of inflammatory responses, can lead to the convergent selection of alleles affecting neutrophil homeostasis. Similar gene combinations may occur in the human with important consequences in the susceptibility to inflammatory or infectious diseases and cancer.

Presence and localization of CCK receptor subtypes in calf pancreas

This study was undertaken to confirm the presence of CCK receptor subtypes in calf pancreas and establish their cellular localization. Using specific antibodies against CCKA and CCKB receptors, somatostatin, glucagon and insulin, we were able to confirm by Western blot the presence of both CCK receptor protein subtypes in the calf pancreas as a 80-85-kDa CCKA receptor and 40-45-kDa CCKB receptor. By immunofluorescence, the CCKB receptor colocalizes with the islets' somatostatin delta cells, confirming what was previously shown in other species, as well as on ductal cells. We could not reproduce in the calf its colocalization with glucagon alpha cells as observed in human and rat. Any specific localization of CCKA receptors with our multiple antibodies failed. Our observation that the CCKB receptor subtype is specifically localized on pancreatic delta cells as well as on ductal cells lets us support the hypothesis that in this species, CCK could be involved in somatostatin metabolism as well as hydrelatic secretion; its effect on enzyme secretion would be indirect.

Bovine pancreatic secretion in the first week of life: potential involvement of intestinal CCK receptors

The aim of this study was to evaluate pancreatic juice secretion of calves in the first postnatal days, and determine a potential involvement of cholecystokinin (CCK) and intestinal CCK receptor in its regulation. Nine neonatal Friesian calves (five controls and four treated intraduodenally with FK480, a CCK-A receptor antagonist) were surgically fitted with a pancreatic duct catheter and a duodenal cannula before the first colostrum feeding. Collections of pancreatic juice and duodenal luminal pressure recordings were started early after recovery from anaesthesia and continued for 6 days. From day 2 or 3 of life, periodic fluctuations in pancreatic secretions were observed in concert with duodenal myoelectric motor complex (MMC) and variations in plasma pancreatic polypeptide (PP) concentrations. Intraduodenal administration of FK480 reduced pancreatic juice secretion while intravenous infusion of CCK had no effect. Immunocytochemistry indicated an association of mucosal CCK-A and -B receptors with neural components of the small intestine. In conclusion, periodic activity of the exocrine pancreas exists in neonatal calves soon after birth and local neural intestinal CCK-A receptors could be partly responsible for the modulation of neonatal calf pancreatic secretion.

cAMP protection of pancreatic cancer cells against apoptosis induced by ERK inhibition

Large increases in cAMP concentration inside the cell are generally growth inhibitory for most cell lines of mesenchymal and epithelial origin. Moreover, recent data suggest a role of cAMP in survival of different cell types. Herein, the ability of forskolin (an adenylyl cyclase activator) and IBMX (3-isobutyl-1-methylxanthine) (a phosphodiesterase inhibitor) to modulate cell cycle progression and survival of human pancreatic cancer cells was evaluated. We showed that forskolin + IBMX inhibited serum-induced ERK activities, Rb hyperphosphorylation, Cdk2 activity, and p27(Kip1) downregulation and caused G1 arrest in MIA PaCa-2 cells. Furthermore, forskolin + IBMX protected pancreatic cells against apoptosis induced by prolonged inhibition of ERK activities by preventing Bcl-X(L) downregulation, activation of caspases 3, 6, 8, and 9, and PARP cleavage and by inducing Bad phosphorylation (ser112). Taken together, our data demonstrate for the first time that cAMP is an inhibitor of cell cycle progression and apoptosis in human pancreatic cancer cells.

MEK/ERK signaling pathway regulates the expression of Bcl-2, Bcl-X(L), and Mcl-1 and promotes survival of human pancreatic cancer cells

BACKGROUND AND AIMS

Growth factors are well known for their participation in the regulation of cell proliferation and survival. However, the intracellular signaling pathways by which growth factors promote survival are still poorly understood. In the present study, using the MIA PaCa-2 cell line, a well-established model of pancreatic cancer cells, we analyzed the roles of ERK1/2 activities in the regulation of cell survival and investigated some of the mechanisms involved.

METHODS

The ability of the MEK inhibitor PD98059 to modulate survival of the MIA PaCa-2 cells was evaluated, and the responses were correlated with expression of Bcl-2 homologs and caspases 1, 3, 6, 8, and 9 activities.

RESULTS

Herein, we showed that inhibition of ERK1/2 activities caused (1) a G1 arrest; (2) a down-regulation of the expression levels of the anti-apoptotic homologs Bcl-2, Mcl-1, and Bcl-X(L) without affecting the pro-apoptotic levels of Bax and Bak; (3) a promotion of caspases 3, 6, 8, and 9 activities; (4) a stimulation of PARP cleavage; and (5) a programmed cell death by apoptosis.

CONCLUSION

Our data suggest that activation of the ERK pathway functions to protect pancreatic tumor cells from apoptosis as well as to regulate their progression in the cell cycle.

Pancreatic inflammation, apoptosis, and growth: sequential events after partial pancreatectomy in pigs

Positive signs of pancreas regeneration were observed in rats after induced pancreatitis and partial pancreatectomy (1,2). Although the human pancreas did not regenerate after partial anatomic resection (3), the pig pancreas exhibited growth responses to bombesin after partial pancreatectomy (4). This study was undertaken to establish the time course of pancreatic inflammation, apoptosis, and hypertrophy and/or hyperplasia after partial pancreatectomy in pigs.

Pancreatic CCK(B) receptors: their potential roles in somatostatin release and delta-cell proliferation

In rodents, cholecystokinin (CCK) induces pancreatic enzyme secretion and pancreas growth through its CCK(A) receptors. It is unknown whether occupation of the CCK(B) receptors present in pig and human pancreas can cause the same effects. This study evaluates CCK(B) receptor expression in rat, mouse, pig, and fetal human pancreata using Northern blot, Western blot, and immunofluorescence techniques. The reported 2.7-kb CCK(B) receptor mRNA transcript in the rat brain and gastric fundus is absent in pancreas; the message was, however, detected by RT-PCR and by a CCK(B) receptor antibody as an 80-kDa protein present uniquely in islet delta-cells. Proteins of 50 and 80 kDa appear in mouse pancreas, and proteins of 50 and 115 kDa appear in pig and human pancreas, respectively, all localized in islet delta-cells. Gastrin mRNAs are strongly present in fetal rat pancreas, and the hormone is localized in islets; both are repressed 10 days after birth. In conclusion, the CCK(B) receptors are present in pancreas of four species with exclusive location in islet delta-cells. In such a location, they could be indirectly involved in the control of enzyme secretion.

Subcellular distribution and characterization of rat pancreatic phospholipase D isoforms

This study was undertaken to characterize the biochemical properties of rat pancreatic phospholipase D (PLD). Based on Western blot analysis of pancreas subcellular fractions, PLD1 was detected as a protein of 120 kDa associated with the microsomal fraction, whereas PLD2 appeared as a 105-kDa protein enriched in the microvesicular fraction. In these fractions, a low level of PLD activity was measured with an exogenous substrate containing phosphatidylinositol-4,5-bisphosphate (PIP2), unresponsive to guanosine triphosphate (GTP)gammaS and adenosine diphosphate (ADP)-ribosylation factor (ARF). Addition of unsaturated but not saturated fatty acids stimulated an oleate-dependent PLD activity that colocalized with the PLD1 enzyme in the crude plasma membrane and microsomal fractions. The transphosphatidylation reaction was maximal with either 200-400 mM (1.2-2.3%) ethanol or 25 mM (0.23%) 1-butanol, with an optimal pH between 6.5 and 7.2. Lipids extracted from the pancreatic membranes were potent inhibitors of the HL60 cell PLD activity when compared with those isolated from HL60 cells. Oleate-dependent PLD activity was less susceptible to these inhibitions. A phospholipase A1 (PLA1) activity hydrolyzing phosphatidylethanol also was found in the pancreatic membrane fractions and was nearly absent in the HL60 cells. This activity was completely inhibited by 400 nM tetrahydrolipstatin (THL), a lipase inhibitor. Pancreatic PLD1 and PLD2 activities could be measured after a chromatographic separation from microsomal membranes and high-speed supernatants, respectively. Activities of both enzymes were inhibited by oleate and required the presence of PIP2 in the substrate vesicles. ARF1 strongly activated PLD1 in a dose-dependent manner, and PLD2 was slightly responsive. Indirect immunofluorescence revealed that PLD2 is distributed throughout the pancreas, with a more intense staining in the islets. This study presents for the first time biochemical characteristics of the pancreatic PLD activities and shows the presence of oleate-dependent PLD1 and PLD2 activities, as well as PLD1 and PLD2 proteins in this gland.

Expression and modulation of p42/p44 MAPKs and cell cycle regulatory proteins in rat pancreas regeneration

Pancreatic growth occurs after CCK, CCK-induced pancreatitis, and pancreatectomy; the mechanisms involved remain unknown. This study evaluates mitogen-activated protein kinase (MAPK) activation and expression of cell cycle regulatory proteins after pancreatectomy to understand the cellular and molecular mechanisms involved in pancreas regeneration. Rats were killed 1-12 days after pancreatectomy, and p42/p44 MAPK activation, expression of the cyclins D and E, cyclin-dependent kinase (Cdk)-2 activity, retinoblastoma protein (pRb) hyperphosphorylation, and expression of the cyclin kinase inhibitors p15, p21, and p27 were examined. Pancreatic remnants exhibited sustained p42/p44 MAPK activation within 8 h. Cyclins D1 and E showed maximal expression after 2 and 6 days, coinciding with maximal hyperphosphorylation of pRb and Cdk2 activity. The expression of p15 vanished after 12 h, p27 disappeared gradually, and p21 increased early. The p27 complexed with Cdk2 dissociated after 2 days, whereas p21 associated in a reverse fashion. In conclusion, sustained activation of p42/p44 MAPKs and Cdk2 along with overexpression of cyclins D1 and E and reduction of p15 and p27 cyclin inhibitors occurred early after pancreatectomy and are active factors involved in signaling that leads to pancreas regeneration.

Activation of MAP kinases in growth responsive pancreatic cancer cells

The implication of MAP kinases in the proliferation control of pancreatic cancer cells is still unknown. This study was undertaken to examine the contribution of the p44/p42 and p38 MAP kinases in the mitogenic response to epidermal growth factor (EGF) and bombesin in human pancreatic cancer cells, MIA PaCa-2 and PANC-1. Data indicate that EGF and bombesin stimulated growth of both cell lines. In MIA PaCa-2 cells, EGF and bombesin stimulated the in gel activation of p38 while p44/p42 kinases exhibited high basal activity and no response to stimuli. Growth and p38 activation were inhibited by genistein, wortmannin, PD98059 and SB203580, specific inhibitors of tyrosine kinase, phosphatidylinositol 3-kinase, MEK-1 and p38 kinases, respectively. In PANC-1 cells, EGF and bombesin stimulated p42 in gel activation; p44 remained highly activated and unresponsive to stimuli and p38 did not respond. Stimulated growth and p42 activation were inhibited by genistein, wortmannin and PD98059. Estimation of MAPK activities with a specific anti-active MAP kinase antibody indicated, however, that EGF increased the intensity of the bands corresponding to p42 and p44 MAP kinases in both cell lines, indicating that the mitogenic factor can regulate MAP kinase activity. Data also pointed out that ATP is sufficient to increase MAP kinase activity within the in gel assay technique and may thus explain the discrepancies existing between the in gel assay data and those obtained with the anti-active MAP kinase antibody.

Ontogeny and species differences in the pancreatic expression and localization of the CCK(A) receptors

We have evaluated the presence and localization of the CCK(A) receptor in rat, mouse, pig and human fetal pancreas by Northern, Western blots and immunofluorescence techniques. In the rat, parallelism exists between development of the CCK(A) receptor mRNA and protein with maximal peaks of expression during the suckling period. In the course of pancreatitis induction, CCK(A) receptor mRNA were maximally expressed and sustained during the gland's regeneration. In the rat and mouse pancreas, the CCK(A) receptor protein is localized around the acinar cells and beta cells of the islets of Langerhans. In the adult pig and fetal human pancreas, the CCK(A) receptor proteins were detected by Western blot. By immunofluorescence, its detection was possible only in the islet of Langerhans of the pig pancreas. These new findings support the views that CCK plays important and various roles in specific physiological systems of the pancreas of different species.

Hormonal control of rat fetal pancreas development

Rat fetal pancreas development and maturation were investigated in vitro and in vivo, and the informations available on their controls do not agree. Our main objective was to reinvestigate fetal pancreas growth in vivo through treatments of the dams during their entire pregnancy. Pregnant rats were thus implanted subcutaneously with Alzet minipumps and received cerulein (0.25 microg kg-1 h-1), gastrin-releasing peptide (GRP; 0.18 microg kg-1 h-1), GRP antagonist (12 microg kg-1 h-1), pentagastrin (2.38 microg kg-1 h-1), L-365,260, a cholecystokinin B (CCKB) receptor antagonist (120 microg kg-1 h-1), and hydrocortisone (417 or 833 microg kg-1 h-1). After sacrifice at the end of pregnancy, the pancreata of the dams and those of their fetuses were excised for weight, protein, RNA, DNA, and digestive enzyme determinations. In the fetus, pancreas growth defined as hyperplasia was observed only in response to hydrocortisone, while aplasia occurred in response to cerulein. Gastrin and the GRP antagonist were the most effective hypertrophic agents, and the effect of the CCKB receptor antagonist was atrophic. In conclusion, hydrocortisone caused proliferation of the fetal rat pancreas, whereas gastrin induced its differentiation and maturation probably through CCKB receptor occupation.

Inhibitory and stimulatory effects of somatostatin on two human pancreatic cancer cell lines: a primary role for tyrosine phosphatase SHP-1

Somatostatin (SS-14) and its structural analogue SMS 201-995 (SMS) are recognized as physiological inhibitors of multiple organs and tissue functions through specific membrane receptors (sst1-sst5). The effects of SS-14 and SMS in the growth control of the pancreatic cancer cell lines MIA PaCa-2 and PANC-1 were investigated to identify and clarify the intracellular events involved. In PANC-1 cells, SS-14 and SMS caused inhibition of their basal growth, and that stimulated by epidermal growth factor, with a maximal effect at 0.1-1 microM. To understand the inhibitory mechanisms, we investigated the effects of SS-14 and SMS on phosphotyrosine phosphatase (PTPase) activity and, more specifically, that of tyrosine phosphatase SHP-1 (PTP1C). SS-14 and SMS caused significant increases in total cellular PTPase activity, and particularly SHP-1, with maximal activation within 1 min. Inhibition of membrane tyrosine kinase and p42 MAP kinase activities was also observed, in response to SS-14 and SMS. In MIA PaCa-2 cells, SS-14 and SMS were associated with a positive growth response at 1-10 nM, after 4 days of culture in serum-free medium. Total cellular PTPase activity was slightly increased, but SHP-1 activity could not be detected; its absence in this cell line was confirmed by Western blot. Membrane tyrosine kinase activities were significantly increased by SS-14 and SMS at concentrations needed for maximal growth. p44/p42, which are constitutively active in this cell line, and p38 activities were not affected by somatostatin. In conclusion, somatostatin can exert different effects on human pancreatic cancer cell growth, depending upon the presence or absence of SHP-1. This enzyme can play a key role in the control of cell proliferation, and its cellular presence may determine the therapeutic potential of somatostatin in the control of cancer cell growth.

Growth effects of regulatory peptides and intracellular signaling routes in human pancreatic cancer cell lines

The intracellular events involved in normal pancreatic growth have been extensively investigated in response to cholecystokinin. Recent data indicate that tyrosine kinase, phospholipase D, phosphatidylinositol 3-kinase, and p42/p44 MAPK are stimulated in rat pancreatic acinar cells. Although we begin to understand the intracellular signaling pathways activated in normal pancreas, such information is not yet available in pancreatic cancer cells. This study was undertaken to identify the growth factors and hormones involved in cell proliferation of two human pancreatic cancer cell lines of ductal origin, the MIA PaCa-2, and PANC-1 cells, and to establish the intracellular events involved in the control of their growth. We demonstrated that FGF-2, IGF-1, cerulein, and gastrin but not FGF-1, HGF, secretin, and PACAP, stimulated proliferation of MIA PaCa-2 and PANC-1 cells. Autocrine factors such as gastrin and IGF-1 were also responsible for their proliferation. In response to EGF, FGF-2, IGF-1, cerulein, gastrin and bombesin, tyrosine kinase, and tyrosine phosphatase activities were stimulated in both cell lines. The close relationship established between cell growth and tyrosine kinase activation results from the observation that maximal growth stimulation paralleled with maximal enzyme activation and that genistein, the tyrosine kinase inhibitor, blocked cell growth and enzyme activation. The implication of PLD in growth-stimulated processes is doubtful since all growth factors and hormones tested failed to stimulate an already very active PLD activity. We finally observed a constitutive activity of p44 MAPK in both cell lines and of p42 in MIA PaCa-2 cells. However, p38 and p42 were stimulated in MIA PaCa-2 and PANC-1 cells, respectively, by all growth factors and hormones.

Clusterin overexpression in rat pancreas during the acute phase of pancreatitis and pancreatic development

Molecular mechanisms associated with apoptosis in pancreas remain largely unknown. Clusterin mRNA is induced in several tissues in response to most apoptotic stimuli. In these tissues, clusterin has an antiapoptotic activity. The aim of this work was to test whether clusterin, which is not expressed in normal pancreas, was induced in pancreas during pancreatitis and pancreatic development. Clusterin mRNA levels were strongly increased 6 h after pancreatitis induction. Maximal expression happened between 24-48 h and decreased progressively to undetectable levels at day 5. Clusterin mRNA was expressed with similar intensity in oedematous caerulein-induced pancreatitis and in response to various degrees of necrohaemorrhagic taurocholate-induced pancreatitis, indicating a maximal gene activity in all types of pancreatitis; in situ hybridization showed that the acinar cells and some ducts expressed clusterin mRNA. A single band of about 35-38 kDa was detected by western blot in pancreatic homogenates and in pancreatic juice from rats with acute pancreatitis, but not from control rats. Clusterin mRNA expression was strong in late fetal life and remains high until day 11 post-partum, then decreased progressively with a minimum from 35 to 90 days post-partum. Clusterin mRNA levels were strongly induced in pancreatic acinar AR4-2J cells in response to various apoptotic stimuli (i.e., cycloheximide, staurosporine, ceramide and H2O2) but not with interleukin (IL)-1, IL-4 or IL-6 or heat shock, which do not induce apoptosis in AR4-2J cells. In conclusion, we demonstrated that clusterin is synthesized and released by the pancreas. Its strong expression during acute pancreatitis suggests its involvement in the pancreatic response to injury. Clusterin is also induced during pancreatic development. Because these situations are associated with apoptosis and clusterin was shown to protect against apoptosis, we speculate that clusterin could be involved in the control of acinar cell apoptosis.

Ontogeny of insulin-like growth factors (IGF), IGF binding proteins, IGF receptors, and growth hormone receptor mRNA levels in porcine pancreas

We examined the ontogeny of mRNA levels of IGF-I and -II, IGF type 1 (IGFI-R) and type II receptors (IGFII-R), IGF binding protein-1 and -3 (IGFBP-1 and -3), GH receptor (GHR), and tissue concentrations of IGF and IGFBP in the pancreas of pigs. Tissues were collected from fetuses at 90 and 110 d of gestation and from pigs at 1, 21, 90 and 180 d of age. Northern blots were performed using total RNA hybridized with 32P-labeled cDNA probes (human IGF-I and human IGFI-R) and cRNA probes (rat IGF-II, human IGFII-R, human IGFBP-1, pig IGFBP-3, and pig GHR). There were two accelerated growth stages of the pancreas: the first one at 90 d of fetal life, which is characterized by cell hyperplasia (high ratio of DNA to body weight), and the second one at postnatal 90 d, which is attributed to cell hypertrophy (high ratios of pancreatic weight, RNA, and protein to DNA). The level of IGF-II mRNA and its tissue concentration were predominant during fetal life and low thereafter. The IGF-I mRNA level was high during fetal and early postnatal life and decreased thereafter. Messenger RNA levels of IGFI-R, IGFBP-3, and GHR and concentrations of IGFBP-1 and -2 were abundant during fetal and early postnatal life. In conclusion, IGF may be involved in various physiological periods of pancreatic development in pigs.

Cloning and expression of the rat p8 cDNA, a new gene activated in pancreas during the acute phase of pancreatitis, pancreatic development, and regeneration, and which promotes cellular growth

To characterize at the molecular level the pancreatic emergency program set up by the pancreatic cells in response to pancreatitis, we have developed a strategy in which the phenotype of the pancreatitis affected pancreas is established by characterization of a large number of its transcripts. Herein, we describe the cloning, sequence, and expression of a new gene, named p8, which is strongly activated in pancreatic acinar cells during the acute phase of pancreatitis, in developing pancreas and during pancreatic regeneration. In acinar cells, p8 mRNA is expressed rapidly and specifically in response to cellular pancreatitis-induced injury; its induction occurred almost similarly in edematous and necrohemorrhagic pancreatitis, indicating that p8 mRNA is maximally activated even in response to a mild pancreatic injury. Furthermore, in vitro studies suggest that p8 mRNA is induced in pancreatic and non-pancreatic cells in response to some apoptotic stimuli. p8 acts as a promoter of cellular growth factor when its cDNA is transfected into COS-7 and AR4-2J cells. Although we failed to identify p8-related sequences, analysis of its primary and secondary structure suggests that p8 is a basic helix-turn-helix-containing gene with slight homology to several homeotic genes and sufficient signal to be targeted to the nucleus. We therefore propose p8 as a putative transcriptional factor which can regulate pancreatic growth.

Establishment and immunocharacterization of an immortalized pancreatic cell line derived from the H-2Kb-tsA58 transgenic mouse

This study describes the establishment and characterization of an immortalized cell line derived from the pancreas of an adult H-2Kb-tsA58 transgenic mouse. These cells, designated IMPAN for IMmortalized PANcreatic cells, displayed a cobblestone appearance typical of confluent epithelial cells and a distinct polarity in the organization of their cytoplasmic organelles. Immunocytochemical studies revealed that all IMPAN cells stained positively for a wide range of markers characteristic of pancreatic acinar cells, namely the secretory products alpha-amylase, chymotrypsinogen, DNAse, the lectinlike secretory protein PAP (pancreatitis associated protein), and the zymogen granule membrane proteins GP-2 and gp300. They also stained positively for carbonic anhydrase II and cytokeratin 19, two proteins characteristic of pancreatic duct cells, as well as for rab3A, a small GTP-binding protein specifically localized in pancreatic islet cells. No reactivity was ever obtained with insulin antibodies. Taken together, these results show that the IMPAN cells exhibit a phenotype comparable to exocrine pancreatic acinar cells. However the expression of some proteins more specific to duct and islet cells make them similar to in vivo or in vitro growing acinar cells. The cell line should be a valuable model to study the mechanisms of growth, differentiation, and transformation of the exocrine pancreatic acinar cell.

Pancreatic GAPDH gene expression during ontogeny and acute pancreatitis induced by caerulein

Recent studies indicated that expression of the housekeeping gene GAPDH is highly regulated during proliferation and differentiation. The objective of this study was to characterize by Northern blot the GAPDH mRNA expression in rat pancreas development and regeneration following acute pancreatitis induction by caerulein. Pancreatic GAPDH mRNA levels were the highest between fetal day 19 and the 11 postnatal day; they decreased to their lowest level after weaning on day 26. In acute pancreatitis, GAPDH mRNA levels were clearly increased 18 h after its initiation, were maximal during the first two days of induction and then decreased to control values after 9 days. These data demonstrate that overexpression of GAPDH may be implicated in pancreatic development, maturation and pancreas regeneration after acute pancreatitis.

Downregulation of IGF-I mRNA expression during postnatal pancreatic development and overexpression after subtotal pancreatectomy and acute pancreatitis in the rat pancreas

Insulin-like growth factors (IGFs) are important peptides involved in the regulation of cell growth and differentiation in many tissues. The ontogeny of IGF-I was examined in pancreata from 19-day rat fetuses, newborns and 5-, 11-, 26- and 70-day-old rats. For the regeneration studies two models were used: (i) 90% pancreatectomy was carried out and the rats were killed at 1, 2, 3 and 6 days after resection; (ii) acute pancreatitis was induced with caerulein (12 micrograms/body weight three times a day every 8 h for 2 days) and the rats were killed at 1, 2, 5, 7 and 9 days after the first injection. Total RNA was extracted by the guanidinium isothiocyanate method and Northern blots were performed using total RNA and labeled cRNA probes. Abundance of the different mRNA transcripts was estimated by densitometric scanning and normalized to the abundance of 18 S rRNA for each time point. Northern blot analysis during ontogeny showed four (0.8-1.2, 1.9, 4.7 and 7.5 kb) major transcripts in the rat pancreas and liver. Total IGF-I mRNA was 40-fold higher in the adult liver than in the adult pancreas. Moreover, in the liver, IGF-I mRNA levels were higher in the adult than in the fetus, whereas in the pancreas, the highest levels were observed around birth. During the first 3 days after pancreatectomy, a peak of maximal expression was observed after the second day. Densitometric analysis of each IGF-I mRNA species showed concomitant increases in all transcripts. After 6 days, all transcripts had returned to near-control values. IGF-I mRNA expression 2 days after pancreatectomy was 3.5-fold higher than in the newborn. During the first 2 days of acute pancreatitis induction, overexpression of IGF-I mRNA was observed. However, soon after the second day of caerulein treatment, the 7.5 kb transcripts remained elevated whereas those of the others regressed toward control values. Our results show that IGF-I mRNA is overexpressed in both models of pancreatic regeneration but downregulated in the normal adult pancreas.

Endogenous arachidonic acid release and pancreatic amylase secretion

Recent studies have suggested the involvement of phospholipase A2 (PLA2) in pancreatic amylase secretion. The present study was designed to investigate the secretory role of arachidonic acid (AA) in carbachol (Cch)-stimulated rat pancreatic acini and its origin. From enzymatic assays, PLA2 and diacylglycerol (DAG) lipase were activated by Cch and respectively inhibited by the PLA2 inhibitors, mepacrine and aristolochic acid, and by the DAG lipase inhibitor, RHC 80267. Melittin-activated PLA2 activity was also inhibited by the PLA2 inhibitors. Cch-stimulated endogenous AA release from pancreatic acini was partially inhibited by 150 microM RHC 80267 and by 150 microM mepacrine or 200 microM aristolochic acid and totally inhibited by a combination of the two enzyme inhibitors. Exogenous AA caused amylase release in a concentration-dependent manner. Eicosatetraynoic acid (a cyclooxygenase and lipoxygenase inhibitor), significantly increased basal and Cch-induced AA release and amylase secretion. RHC 80267 and the PLA2 inhibitors separately and partially suppressed Cch-stimulated amylase secretion, with an additive effect observed when the DAG lipase and the PLA2 inhibitors were combined. A combination of RHC 80267, mepacrine, or aristolochic acid and the phospholipase C (PLC) inhibitor U73122 completely inhibited Cch-stimulated amylase secretion. Finally, the PLA2 activator melittin-stimulated amylase secretion was blocked by the two PLA2 inhibitors. We conclude that exogenous and endogenous AA can induce amylase secretion. Therefore, AA released from either PLC-DAG lipase or PLA2 pathways can be considered an additional and important intracellular mediator of amylase secretion.

Models of exocrine pancreatic pathologies: a microscopical point of view

The objective of this review is to emphasize the contribution of optical and electronic microscopy to the study of the normal and pathological rat pancreas. These basic techniques used to explore the pancreatic morphology are capital to precisely localize specific enzymes or proteins in cellular subcompartments, to establish the normal or the pathological state of the gland, and to detect and describe unusual structures that appear under certain experimental conditions.

Localization of rat pancreatitis-associated protein during bile salt-induced pancreatitis

BACKGROUND & AIMS

Pancreatitis-associated protein (PAP), which is overexpressed in pancreatic acinar cells, appears in pancreatic juice and serum after acute pancreatitis. The aim of this study was to examine intracellular localization of PAP and amylase in healthy rat pancreas and pancreatitis pancreas to ascertain PAP transport from the rough endoplasmic reticulum to the zymogen granules into the acinar lumen.

METHODS

Control rats and rats with taurocholate-induced pancreatitis were killed after 24 hours. Pancreata prepared for light and electron microscopy were used for amylase and PAP detection with specific antibodies.

RESULTS

Induced acute pancreatitis disturbed the gross histology and ultrastructure of the acinar cells with the formation of new intracellular fibrous material into the cytoplasm, which was also found into the acinar lumen. PAP is almost absent from normal acinar cells; after acute pancreatitis, it appears in rough endoplasmic reticulum, it is strongly present in normal and abnormal zymogen granules, and it remains an important component of the fibrous material. Except for its exclusive presence in fibrous material, PAP is always colocalized with amylase in the other cell compartments.

CONCLUSIONS

These observations show that the accumulated PAP into the acinar cells in response to acute pancreatitis behaves like all the other secretory proteins with the exception that it also accumulates in a new fibrillous cellular structure also found in the acinar lumen.

Modulation of pancreatic secretion of individual digestive enzymes in octreotide (SMS 201-995)-infused rats

We demonstrated previously that pancreatic secretion of individual enzymes is specifically regulated (1). In the present study, we investigated and defined contributing roles of cholinergic and cholecystokinin tones to the specific regulation of rat pancreatic secretion of digestive enzymes. Animals were provided with pancreatic, biliary, duodenal, and jugular vein cannulas allowing separate drainage of bile and pure pancreatic juice, as well as intravenous infusions of MK329 or atropine sulfate along with SMS 201-995 (SMS). Rats kept in restraint cages were divided into four groups. The first rat group was infused with 5 micrograms kg-1 h-1 SMS alone; the second group was infused with a mixture of SMS and MK329 (5 micrograms kg-1 h-1:0.5 mg kg-1 h-1); the third group received a mixture of SMS and atropine (5 micrograms kg-1 h-1); and rats in the fourth group were administrated a mixture of SMS, MK329, and atropine (5 micrograms kg-1 h-1:0.5 mg kg-1:100 micrograms kg-1 h-1). Food, but not water, was denied rats 10 h before the experiment and throughout the 6-h experimental period. During the experiment, pancreatic juice was continuously collected every 15 min from each rat, and a 15-microliter aliquot of the pancreatic juice sample was removed for total protein, amylase, lipase, trypsinogen, chymotrypsinogen, and proelastase assays. Pancreatic juice previously collected from a donor rat was mixed with the fresh bile and the mixture was recirculated into the duodenum. The secretory patterns over the 6-h experimental period showed that during the first hour of drug infusion, MK329 alone did not alter the SMS-induced inhibitory process of total protein and amylase, trypsinogen, and proelastase secretion, and there was no marked change in total protein and enzyme outputs. Adding atropine to SMS did not alter the secretory pattern during the first hour of drug infusion, but a significantly greater decrease in protein and enzymes outputs occurred. Correlations between paired enzyme outputs greatly increased with SMS alone, but some changed when either MK329 or atropine was infused along with SMS. When all drugs were infused together, enzyme outputs became strongly correlated. These results suggest that under fasting conditions, somatostatin and atropine can neutralize basal pancreatic enzyme outputs, leading to a constitutive type of secretion characterized by parallel secretion of the digestive enzymes. Furthermore, it is proposed that under basal secretion conditions, acetylcholine and cholecystokinin reaching the pancreatic acinar cells may act to dissociate pancreatic secretion of individual digestive enzymes originating from heterogeneous secretory granules.

Ontogeny of hepatocyte growth factor and c-met/hgf receptor in rat pancreas

Hepatocyte growth factor has several activities in epithelial cells, including mitogenesis, dissociation of epithelial sheets, stimulation of motility, and promotion of matrix invasion. HGF is the ligand of a dimeric transmembrane tyrosine kinase receptor encoded by the met proto-oncogene. The objective of this study was to characterize by Northern blot the HGF and c-met mRNA expression in rat pancreas during development. Our findings show that simultaneous expression of both messengers occurs during the early development of the rat pancreas. Pancreatic HGF and c-met mRNA levels were higher between late fetal and 11 post-natal days and then decreased to a very low level at 26 days. This low level was maintained until the adult age. We conclude that HGF gene expression and c-met pancreatic gene expression are age dependent with the highest expression before weaning. These new data demonstrate that HGF and its receptor may be implicated in normal pancreas development and maturation.

Increases in Ki-ras and ornithine decarboxylase gene expression in rat pancreas after caerulein-induced pancreatitis

Caerulein-induced pancreatitis (CIP) in rats is characterized by oedema and cell necrosis followed by spontaneous regeneration. The ras protein as well as ornithine decarboxylase (ODC) play a central role in the transmission of signals induced by growth factors. Therefore, we analyzed these gene products during the course of CIP and during the regeneration of the gland. Growth and biochemical parameters (pancreatic weight, total DNA, RNA and proteins) were determined along with ODC activity and quantitative reverse-transcriptase polymerase chain reaction measurements of mRNA levels. During CIP, the significant increases in pancreatic weight were the result of oedema. During that period, maximal increases in ODC activity were observed at 3 h, in ODC mRNA expression at 2, 3, and 4 h, and in Ki-ras mRNA expression at 1 h. During the 3-day resting period within which no treatment was given, pancreatic weight exhibited its maximal reduction after 2 days in the CIP group. In that same group, the ODC activity reached its maximal level above control after 3 days and ODC and Ki-ras mRNA expression after 1 and 2 days. During the regeneration period of 5 days, the pancreata of the untreated pancreatitis rats did not totally recover, whereas those of the animals receiving the small dose of caerulein (1 microgram) showed full recovery and even a significant increase above control after 5 days. During that period, maximal increases in ODC activity and Ki-ras mRNA expression occurred after 1 day of caerulein treatment; ODC mRNA expression was also significantly increased after 3 and 5 days in the pancreatitis animals with no effect of caerulein treatment. The positive effect of caerulein on Ki-ras mRNA suggests that the cholecystokinin analogue can induce the expression of essential growth-promoting genes.