Alterations in EGF binding to acini during pancreatic regeneration in the rat

Epidermal growth factor serum levels and the 61 G/A polymorphism in patients with acute pancreatitis

BACKGROUND

Epidermal growth factor (EGF) binds to pancreatic acinar cells and facilitates recovery from acute pancreatitis (AP). In animal models, EGF protects against pancreatic injury and prevents septic complications. The role of EGF in human AP is unknown.

AIMS

The aim of this study was to assess EGF serum levels in AP patients and whether the EGF +61 G/A single nucleotide polymorphism (SNP) affects susceptibility and/or severity of AP.

METHODS

Hospitalized AP patients were prospectively enrolled. Demographics, clinical features, DNA and early serum samples were collected when available. Patients were classified into mild (79%) and severe AP (21%) based on organ failure for >or=48 h. Early serum samples were quantitatively assayed for EGF levels. The EGF +61 G/A SNP was evaluated by restriction fragment length polymorphism analysis.

RESULTS

There were 179 patients ascertained with AP. EGF levels were measured in a subgroup of 60 patients with early serum samples (17 severe) and in serum from 58 healthy controls. Serum EGF levels within 48 h from the onset of pain were significantly lower in AP patients (mean 13.5 pg/ml) compared to controls (25.2 pg/ml; P=0.015). Furthermore, EGF levels were significantly lower in severe patients when compared to mild (7.8 vs. 14.3 pg/ml; P=0.026). DNA from all 179 patients and 189 healthy controls was sequenced. The EGF +61 G/A SNP did not affect susceptibility to or severity of AP.

CONCLUSIONS

EGF serum levels are decreased early in the course of AP and are further suppressed in severe AP. The EGF +61 G/A polymorphism has no effect on AP.

Epidermal growth factor receptor expression in pancreatic lesions induced in the rat by azaserine

In the present study, the expression of the epidermal growth factor receptor (EGFR) was investigated in putative preneoplastic and neoplastic acinar cell lesions induced in the rat pancreas by azaserine, using Northern blotting, in situ hybridisation (ISH) and immunohistochemistry. EGFR protein levels were decreased in putative preneoplastic eosinophilic acinar cell lesions (atypical acinar cell nodules, AACN) in comparison with normal acinar cells of the pancreas. However, EGFR mRNA expression correlated positively with the volume of AACN in pancreatic homogenates and ISH showed equal or stronger EGFR mRNA expression in AACN than in the surrounding normal acinar cells. Neither EGFR protein nor EGFR mRNA was detected in more advanced lesions such as acinar adenocarcinomas (in situ). Moreover, EGFR protein expression showed an inverse relationship with the mitotic rate of the acinar cells. These findings suggest that down-regulation of EGFR at the protein level may abrogate negative constraints on cell growth, which may stimulate the development of putative preneoplastic AACN to more advanced lesions and, ultimately, acinar adenocarcinomas.

Secretion of protein and epidermal growth factor (EGF) by transplanted human pancreas

Epidermal growth factor (EGF) has been localized in human salivary and Brunner's glands and found to stimulate the proliferation of gastrointestinal and pancreatic tissues in animals, but little is known about EGF in human pancreas. This study was designed to determine the distribution and release of EGF in the pancreas and to assess the secretion of EGF and protein by the transplanted human pancreas. The peroxidase antiperoxidase (PAP) immunocytochemical method with anti-hEGF showed that EGF was restricted mainly to the excretory cells lining pancreatic ducts. The EGF immunoreactivity in the pancreatic tissue averaged about 15 +/- 0.5 micrograms/g of tissue wt. The concentration and output of EGF in the pancreatic juice were, respectively, about 3.4 +/- 0.7 ng/mL and 68 + 12 ng/h in basal secretion collected from the whole pancreatic transplant. A significant increase in EGF release from this transplant started about 2 h after its reperfusion and was accompanied by a parallel increase in protein output. Injection of iv secretion (1 U/kg) resulted in a transient rise in EGF output, probably as a result of washout by increased vol flow, whereas HCCK (1 U/kg) caused more prolonged release of EGF accompanied by a marked stimulation of protein secretion. Ingestion of a mixed meal caused an immediate and sustained increment in EGF output, and protein output showed a more protracted increase, reaching its peak in the second postprandial hour. Fractionation of an extract of pancreatic juice on G-5O Sephadex superfine column revealed that EGF immunoreactivity emerged as a major peak in the same position as authentic human EGF (hEGF).(ABSTRACT TRUNCATED AT 250 WORDS)

Release and binding of epidermal growth factor in the pancreas of rats

Previous studies showed that EGF is produced by salivary and duodenal glands and released in saliva and duodenal secretion. Using specific radioimmunoassay of EGF, this study showed that the salivary glands and duodenal mucosa contain high levels of EGF, reaching, respectively, about 38 and 4 micrograms/g of tissue weight. EGF immunoreactivity was also found in high amounts in the pancreatic tissue (20 micrograms/g) and the pancreatic juice (32 ng/mL), where the content of EGF was found to increase in response to feeding, cholecystokinin, or bombesin and to decrease after the administration of atropine and somatostatin. Studies on the binding of EGF revealed that pancreatic acinar membranes possess the specific and saturable EGF receptors with a high affinity sites with Kd of about 4.3 nM and binding capacity of about 62 fmol/mg of protein, and with low affinity sites with Kd of 21 nM and binding capacity of about 180 fmol/mg of protein. The observed high content of immunoreactive EGF in the pancreatic tissue and the presence of high and low affinity binding sites for EGF in the pancreatic acinar membranes, as well as the high EGF output in the pancreatic juice and its alterations in response to hormonal and postprandial stimulation, suggest an important role of EGF in pancreatic physiology.