RABBIT PANCREATIC-POLYPEPTIDE

1. In almost all studies involving localization or quantitation of regulatory peptides, an essential prerequisite is the generation of specific antisera in rabbits. Despite this almost universal practice, the primary structures of some established regulatory peptides, such as pancreatic polypeptide (PP), of the rabbit, remain unknown.

THE PRIMARY STRUCTURE OF PANCREATIC-POLYPEPTIDE FROM A PRIMITIVE INSECTIVOROUS MAMMAL, THE EUROPEAN HEDGEHOG (ERINACEOUS-EUROPAEUS)

Pancreatic polypeptide (PP) has been isolated from extracts of the pancreas of the European hedgehog (Erinaceous europaeus) which is a representative of the order Insectivora, deemed to be the most primitive group of placental mammals. Pancreatic tissues were extracted in acidified ethanol and the peptide was purified chromatographically using a PP C-terminal hexapeptide amide specific radioimmunoassay to monitor purification. Two major PP-immunoreactive peptides were baseline-resolved following the final analytical reverse phase HPLC fractionation. Each was separately subjected to plasma desorption mass spectroscopy (PDMS) and gas-phase sequencing. The molecular masses of each peptide were similar: (I) 4237.6 +/- 4 Da and (II) 4238.2 +/- 4 Da. The full primary structures of each peptide were deduced and these were identical: VPLEPVYPGDNATPEQMAHYAAELRRYINMLTRPRY. The peptides were deemed to be amidated due to their full molar cross-reactivity with the amide-requiring PP antiserum employed in radioimmunoassay. The molecular mass (4233.8 Da) calculated from the sequence was in close agreemeent with PDMS estimates and the reason for the different retention times of each peptide is unknown at present. Hedgehog PP exhibits only 2 unique amino acid substitutions, at positions 1 (Val) and 19 (His), when compared with other mammalian analogues.

Antitumor alkyl-lysophospholipid analog edelfosine induces apoptosis in pancreatic cancer by targeting endoplasmic reticulum

Pancreatic cancer remains as one of the most deadly cancers, and responds poorly to current therapies. The prognosis is extremely poor, with a 5-year survival of less than 5%. Therefore, search for new effective therapeutic drugs is of pivotal need and urgency to improve treatment of this incurable malignancy. Synthetic alkyl-lysophospholipid analogs (ALPs) constitute a heterogeneous group of unnatural lipids that promote apoptosis in a wide variety of tumor cells. In this study, we found that the anticancer drug edelfosine was the most potent ALP in killing human pancreatic cancer cells, targeting endoplasmic reticulum (ER). Edelfosine was taken up in significant amounts by pancreatic cancer cells and induced caspase-and mitochondrial-mediated apoptosis. Pancreatic cancer cells show a prominent ER and edelfosine accumulated in this subcellular structure, inducing a potent ER stress response, with caspase-4, BAP31 and c-Jun NH 2-terminal kinase (JNK) activation, CHOP/GADD153 upregulation and phosphorylation of eukaryotic translation initiation factor 2 a-subunit that eventually led to cell death. Oral administration of edelfosine in xenograft mouse models of pancreatic cancer induced a significant regression in tumor growth and an increase in apoptotic index, as assessed by TUNEL assay and caspase-3 activation in the tumor sections. The ER stress-associated marker CHOP/GADD153 was visualized in the pancreatic tumor isolated from edelfosine-treated mice, indicating a strong in vivo ER stress response. These results suggest that edelfosine exerts its pro-apoptotic action in pancreatic cancer cells, both in vitro and in vivo, through its accumulation in the ER, which leads to ER stress and apoptosis. Thus, we propose that the ER could be a key target in pancreatic cancer, and edelfosine may constitute a prototype for the development of a new class of antitumor drugs targeting the ER. © 2012 Macmillan Publishers Limited All rights reserved.

Slug-dependent upregulation of L1CAM is responsible for the increased invasion potential of pancreatic cancer cells following long-term 5-FU treatment

BACKGROUND: Pancreatic adenocarcinoma is a lethal disease with 5-year survival of less than 5%. 5-fluorouracil (5-FU) is a principal first-line therapy, but treatment only extends survival modestly and is seldom curative. Drug resistance and disease recurrence is typical and there is a pressing need to overcome this. To investigate acquired 5-FU resistance in pancreatic adenocarcinoma, we established chemoresistant monoclonal cell lines from the Panc 03.27 cell line by long-term exposure to increasing doses of 5-FU.

RESULTS: 5-FU-resistant cell lines exhibited increased expression of markers associated with multidrug resistance explaining their reduced sensitivity to 5-FU. In addition, 5-FU-resistant cell lines showed alterations typical for an epithelial-to-mesenchymal transition (EMT), including upregulation of mesenchymal markers and increased invasiveness. Microarray analysis revealed the L1CAM pathway as one of the most upregulated pathways in the chemoresistant clones, and a significant upregulation of L1CAM was seen on the RNA and protein level. In pancreatic cancer, expression of L1CAM is associated with a chemoresistant and migratory phenotype. Using esiRNA targeting L1CAM, or by blocking the extracellular part of L1CAM with antibodies, we show that the increased invasiveness observed in the chemoresistant cells functionally depends on L1CAM. Using esiRNA targeting β-catenin and/or Slug, we demonstrate that in the chemoresistant cell lines, L1CAM expression depends on Slug rather than β-catenin.

CONCLUSION: Our findings establish Slug-induced L1CAM expression as a mediator of a chemoresistant and migratory phenotype in pancreatic adenocarcinoma cells.

Pancreatic cancer: medical management (novel chemotherapeutics)

Pancreatic adenocarcinoma is the fourth leading cause of cancer death and has an extremely poor prognosis: The 5-year survival probability is less than 5% for all stages. The only chance for cure or longer survival is surgical resection; however, only 10% to 20% of patients have resectable disease. Although surgical techniques have improved, most who undergo complete resection experience a recurrence. Adjuvant systemic therapy reduces the recurrence rate and improves outcomes. There is a potential role for radiation therapy as part of treatment for locally advanced disease, although its use in both the adjuvant and neoadjuvant settings remains controversial. Palliative systemic treatment is the only option for patients with metastatic disease. To date, however, only the gemcitabine plus erlotinib combination, and recently the FOLFIRINOX regimen, have been associated with relatively small but statistically significant improvements in OS when compared directly with gemcitabine alone. Although several meta-analyses have suggested a benefit associated with combination chemotherapy, whether this benefit is clinically meaningful remains unclear, particularly in light of the enhanced toxicity associated with combination regimens. There is growing evidence that the exceptionally poor prognosis in PC is caused by the tumor's characteristic abundant desmoplastic stroma that plays a critical role in tumor cell growth, invasion, metastasis, and chemoresistance. Carefully designed clinical trials that include translational analysis will provide a better understanding of the tumor biology and its relation to the host stromal cells. Future directions will involve testing of new targeted agents, understanding the pharmacodynamics of our current targeted agents, searching for predictive and prognostic biomarkers, and exploring the efficacy of different combinations strategies.

Reduced risk of pancreatic cancer associated with asthma and nasal allergies

OBJECTIVE: Studies indicate an inverse association between ductal adenocarcinoma of the pancreas (PDAC) and nasal allergies. However, controversial findings are reported for the association with asthma. Understanding PDAC risk factors will help us to implement appropriate strategies to prevent, treat and diagnose this cancer. This study assessed and characterised the association between PDAC and asthma and corroborated existing reports regarding the association between allergies and PDAC risk.

DESIGN: Information about asthma and allergies was collated from 1297 PDAC cases and 1024 controls included in the PanGenEU case-control study. Associations between PDAC and atopic diseases were studied using multilevel logistic regression analysis. Meta-analyses of association studies on these diseases and PDAC risk were performed applying random-effects model.

RESULTS: Asthma was associated with lower risk of PDAC (OR 0.64, 95% CI 0.47 to 0.88), particularly long-standing asthma (>=17 years, OR 0.39, 95% CI 0.24 to 0.65). Meta-analysis of 10 case-control studies sustained our results (metaOR 0.73, 95% CI 0.59 to 0.89). Nasal allergies and related symptoms were associated with lower risk of PDAC (OR 0.66, 95% CI 0.52 to 0.83 and OR 0.59, 95% CI 0.46 to 0.77, respectively). These results were supported by a meta-analysis of nasal allergy studies (metaOR 0.6, 95% CI 0.5 to 0.72). Skin allergies were not associated with PDAC risk.

CONCLUSIONS: This study shows a consistent inverse association between PDAC and asthma and nasal allergies, supporting the notion that atopic diseases are associated with reduced cancer risk. These results point to the involvement of immune and/or inflammatory factors that may either foster or restrain pancreas carcinogenesis warranting further research to understand the molecular mechanisms driving this association.