Ras activity in acinar cells links chronic pancreatitis and pancreatic cancer

Deciphering cellular plasticity in pancreatic cancer for effective treatments

Cellular plasticity and therapy resistance are critical features of pancreatic cancer, a highly aggressive and fatal disease. The pancreas, a vital organ that produces digestive enzymes and hormones, is often affected by two main types of cancer: the pre-dominant ductal adenocarcinoma and the less common neuroendocrine tumors. These cancers are difficult to treat due to their complex biology characterized by cellular plasticity leading to therapy resistance. Cellular plasticity refers to the capability of cancer cells to change and adapt to different microenvironments within the body which includes acinar-ductal metaplasia, epithelial to mesenchymal/epigenetic/metabolic plasticity, as well as stemness. This plasticity allows heterogeneity of cancer cells, metastasis, and evasion of host's immune system and develops resistance to radiation, chemotherapy, and targeted therapy. To overcome this resistance, extensive research is ongoing exploring the intrinsic and extrinsic factors through cellular reprogramming, chemosensitization, targeting metabolic, key survival pathways, etc. In this review, we discussed the mechanisms of cellular plasticity involving cellular adaptation and tumor microenvironment and provided a comprehensive understanding of its role in therapy resistance and ways to overcome it.

CREB activation drives acinar to ductal reprogramming and promote pancreatic cancer progression in animal models of alcoholic chronic pancreatitis

BACKGROUND AND AIMS

In vivo induction of alcoholic chronic pancreatitis (ACP) causes significant acinar damage, increased fibroinflammatory response, and heightened activation of cyclic response element binding protein 1 (CREB) when compared with alcohol (A) or chronic pancreatitis (CP) mediated pancreatic damage. However, the study elucidating the cooperative interaction between CREB and the oncogenic Kras G12D/+ (Kras*) in promoting pancreatic cancer progression with ACP remains unexplored.

METHODS

Experimental ACP induction was established in multiple mouse models, followed by euthanization of the animals at various time intervals during the recovery periods. Tumor latency was determined in these mice cohorts. Here, we established CREB deletion (Creb fl/fl ) in Ptf1a CreERTM/+ ;LSL-Kras G12D+/-(KC) genetic mouse models (KCC-/-). Western blot, phosphokinase array, and qPCR were used to analyze the pancreata of Ptf1a CreERTM+/-, KC and KCC -/- mice. The pancreata of ACP-induced KC mice were subjected to single-cell RNA sequencing (scRNAseq). Further studies involved conducting lineage tracing and acinar cell explant cultures.

RESULTS

ACP induction in KC mice had detrimental effects on the pancreatic damage repair mechanism. The persistent existence of acinar cell-derived ductal lesions demonstrated a prolonged state of hyperactivated CREB. Persistent CREB activation leads to acinar cell reprogramming and increased pro-fibrotic inflammation in KC mice. Acinar-specific Creb ablation reduced advanced PanINs lesions, hindered tumor progression, and restored acinar cell function in ACP-induced mouse models.

CONCLUSIONS

Our findings demonstrate that CREB cooperates with Kras* to perpetuate an irreversible ADM and PanIN formation. Moreover, CREB sustains oncogenic activity to promote the progression of premalignant lesions toward cancer in the presence of ACP.

Krüppel-like Factor 5 Plays an Important Role in the Pathogenesis of Chronic Pancreatitis

Chronic pancreatitis results in the formation of pancreatic intraepithelial neoplasia (PanIN) and poses a risk of developing pancreatic cancer. Our previous study demonstrated that Krüppel-like factor 5 (KLF5) is necessary for forming acinar-to-ductal metaplasia (ADM) in acute pancreatitis. Here, we investigated the role of KLF5 in response to chronic injury in the pancreas. Human tissues originating from chronic pancreatitis patients showed increased levels of epithelial KLF5. An inducible genetic model combining the deletion of Klf5 and the activation of KrasG12D mutant expression in pancreatic acinar cells together with chemically induced chronic pancreatitis was used. The chronic injury resulted in increased levels of KLF5 in both control and KrasG12D mutant mice. Furthermore, it led to numerous ADM and PanIN lesions and extensive fibrosis in the KRAS mutant mice. In contrast, pancreata with Klf5 loss (with or without KrasG12D) failed to develop ADM, PanIN, or significant fibrosis. Furthermore, the deletion of Klf5 reduced the expression level of cytokines and fibrotic components such as Il1b, Il6, Tnf, Tgfb1, Timp1, and Mmp9. Notably, using ChIP-PCR, we showed that KLF5 binds directly to the promoters of Il1b, Il6, and Tgfb1 genes. In summary, the inactivation of Klf5 inhibits ADM and PanIN formation and the development of pancreatic fibrosis.

Pancreatic acinar cell fate relies on system xC- to prevent ferroptosis during stress

Acinar cell dedifferentiation is one of the most notable features of acute and chronic pancreatitis. It can also be the initial step that facilitates pancreatic cancer development. In the present study, we further decipher the precise mechanisms and regulation using primary human cells and murine experimental models. Our RNAseq analysis indicates that, in both species, early acinar cell dedifferentiation is accompanied by multiple pathways related to cell survival that are highly enriched, and where SLC7A11 (xCT) is transiently upregulated. xCT is the specific subunit of the cystine/glutamate antiporter system xC-. To decipher its role, gene silencing, pharmacological inhibition and a knock-out mouse model were used. Acinar cells with depleted or reduced xCT function show an increase in ferroptosis relating to lipid peroxidation. Lower glutathione levels and more lipid ROS accumulation could be rescued by the antioxidant N-acetylcysteine or the ferroptosis inhibitor ferrostatin-1. In caerulein-induced acute pancreatitis in mice, xCT also prevents lipid peroxidation in acinar cells. In conclusion, during stress, acinar cell fate seems to be poised for avoiding several forms of cell death. xCT specifically prevents acinar cell ferroptosis by fueling the glutathione pool and maintaining ROS balance. The data suggest that xCT offers a druggable tipping point to steer the acinar cell fate in stress conditions.

Hematopoietic progenitor kinase 1 inhibits the development and progression of pancreatic intraepithelial neoplasia

Ras plays an essential role in the development of acinar-to-ductal metaplasia (ADM) and pancreatic ductal adenocarcinoma (PDAC). However, mutant Kras is an inefficient driver for PDAC development. The mechanisms of the switching from low Ras activity to high Ras activity that are required for development and progression of pancreatic intraepithelial neoplasias (PanINs) are unclear. In this study, we found that hematopoietic progenitor kinase 1 (HPK1) was upregulated during pancreatic injury and ADM. HPK1 interacted with the SH3 domain and phosphorylated Ras GTPase-activating protein (RasGAP) and upregulated RasGAP activity. Using transgenic mouse models of HPK1 or M46, a kinase-dead mutant of HPK1, we showed that HPK1 inhibited Ras activity and its downstream signaling and regulated acinar cell plasticity. M46 promoted the development of ADM and PanINs. Expression of M46 in KrasG12D Bac mice promoted the infiltration of myeloid-derived suppressor cells and macrophages, inhibited the infiltration of T cells, and accelerated the progression of PanINs to invasive and metastatic PDAC, while HPK1 attenuated mutant Kras-driven PanIN progression. Our results showed that HPK1 plays an important role in ADM and the progression of PanINs by regulating Ras signaling. Loss of HPK1 kinase activity promotes an immunosuppressive tumor microenvironment and accelerates the progression of PanINs to PDAC.

Acinar cells and the development of pancreatic fibrosis

Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.

The Role of Krüppel-like Factors in Pancreatic Physiology and Pathophysiology

Krüppel-like factors (KLFs) belong to the family of transcription factors with three highly conserved zinc finger domains in the C-terminus. They regulate homeostasis, development, and disease progression in many tissues. It has been shown that KLFs play an essential role in the endocrine and exocrine compartments of the pancreas. They are necessary to maintain glucose homeostasis and have been implicated in the development of diabetes. Furthermore, they can be a vital tool in enabling pancreas regeneration and disease modeling. Finally, the KLF family contains proteins that act as tumor suppressors and oncogenes. A subset of members has a biphasic function, being upregulated in the early stages of oncogenesis and stimulating its progression and downregulated in the late stages to allow for tumor dissemination. Here, we describe KLFs' function in pancreatic physiology and pathophysiology.

5-FU-miR-15a Inhibits Activation of Pancreatic Stellate Cells by Reducing YAP1 and BCL-2 Levels In Vitro

Chronic pancreatitis is characterized by chronic inflammation and fibrosis, processes heightened by activated pancreatic stellate cells (PSCs). Recent publications have demonstrated that miR-15a, which targets YAP1 and BCL-2, is significantly downregulated in patients with chronic pancreatitis compared to healthy controls. We have utilized a miRNA modification strategy to enhance the therapeutic efficacy of miR-15a by replacing uracil with 5-fluorouracil (5-FU). We demonstrated increased levels of YAP1 and BCL-2 (both targets of miR-15a) in pancreatic tissues obtained from Ptf1aCreERTM and Ptf1aCreERTM;LSL-KrasG12D mice after chronic pancreatitis induction as compared to controls. In vitro studies showed that delivery of 5-FU-miR-15a significantly decreased viability, proliferation, and migration of PSCs over six days compared to 5-FU, TGFβ1, control miR, and miR-15a. In addition, treatment of PSCs with 5-FU-miR-15a in the context of TGFβ1 treatment exerted a more substantial effect than TGFβ1 alone or when combined with other miRs. Conditioned medium obtained from PSC cells treated with 5-FU-miR-15a significantly inhibits the invasion of pancreatic cancer cells compared to controls. Importantly, we demonstrated that treatment with 5-FU-miR-15a reduced the levels of YAP1 and BCL-2 observed in PSCs. Our results strongly suggest that ectopic delivery of miR mimetics is a promising therapeutic approach for pancreatic fibrosis and that 5-FU-miR-15a shows specific promise.

Chronic inflammation promotes epithelial-mesenchymal transition-mediated malignant phenotypes and lung injury in experimentally-induced pancreatitis

Patients with chronic pancreatitis have an increased risk of pancreatic malignancy, but the mechanisms underlying this relationship are poorly understood. We developed a mouse model of chronic pancreatitis by treatment with a combination of cerulein and azoxymethane. In our model, we show that cerulein and azoxymethane treated mice develop pathological malignant phenotype and associated lung inflammation. We observed chronic pancreatitis-associated induction of proinflammatory cytokines such as interleukin-6, interleukin-15, and granulocyte-macrophage colony-stimulating factor, along with accumulation of macrophages and eosinophilic inflammation. We also observed eosinophils degranulation, pancreatic stellate cell activation-mediated epithelial-to-mesenchymal transition-associated proteins that display a pancreatic malignant phenotype including acinar-to-ductal metaplasia and acinar cell atrophy. We observed highly induced interleukin-15 that has been earlier reported to have a protective role against fibrosis and malignancy; therefore, further evaluated its role in our mouse model of chronic pancreatitis. We observed that introduction of recombinant interleukin-15 has indeed improve chronic pancreatitis-associated epithelial-to-mesenchymal transition-mediated development of a malignant phenotype in the mouse model of chronic pancreatitis. In conclusion, we present evidence that rIL-15 overexpression improves eosinophilic inflammation-induced epithelial-to-mesenchymal transition-mediated progression of pancreatic remodeling associated malignant phenotype and acute lung injury by inducing NKT cells and IFN-γ mediated innate immunity in experimental pancreatitis.

REG3A/REG3B promotes acinar to ductal metaplasia through binding to EXTL3 and activating the RAS-RAF-MEK-ERK signaling pathway

Persistent acinar to ductal metaplasia (ADM) is a recently recognized precursor of pancreatic ductal adenocarcinoma (PDAC). Here we show that the ADM area of human pancreas tissue adjacent to PDAC expresses significantly higher levels of regenerating protein 3A (REG3A). Exogenous REG3A and its mouse homolog REG3B induce ADM in the 3D culture of primary human and murine acinar cells, respectively. Both Reg3b transgenic mice and REG3B-treated mice with caerulein-induced pancreatitis develop and sustain ADM. Two out of five Reg3b transgenic mice with caerulein-induced pancreatitis show progression from ADM to pancreatic intraepithelial neoplasia (PanIN). Both in vitro and in vivo ADM models demonstrate activation of the RAS-RAF-MEK-ERK signaling pathway. Exostosin-like glycosyltransferase 3 (EXTL3) functions as the receptor for REG3B and mediates the activation of downstream signaling proteins. Our data indicates that REG3A/REG3B promotes persistent ADM through binding to EXTL3 and activating the RAS-RAF-MEK-ERK signaling pathway. Targeting REG3A/REG3B, its receptor EXTL3, or other downstream molecules could interrupt the ADM process and prevent early PDAC carcinogenesis.

Migrated Inferior Vena Cava (IVC) Filter Strut: A Rare Cause of Chronic Distal Pancreatitis with Likely Malignant Transformation

Patient: Female, 44-year-old

Final Diagnosis: Pancreatic adenocarcinoma

Symptoms: Abdominal pain

Medication:—

Clinical Procedure: Neoplasm

Specialty: Surgery

The Role of Mitochondria in the Chemoresistance of Pancreatic Cancer Cells

The first-line chemotherapies for patients with unresectable pancreatic cancer (PC) are 5-fluorouracil (5-FU) and gemcitabine therapy. However, due to chemoresistance the prognosis of patients with PC has not been significantly improved. Mitochondria are essential organelles in eukaryotes that evolved from aerobic bacteria. In recent years, many studies have shown that mitochondria play important roles in tumorigenesis and may act as chemotherapeutic targets in PC. In addition, according to recent studies, mitochondria may play important roles in the chemoresistance of PC by affecting apoptosis, metabolism, mtDNA metabolism, and mitochondrial dynamics. Interfering with some of these factors in mitochondria may improve the sensitivity of PC cells to chemotherapeutic agents, such as gemcitabine, making mitochondria promising targets for overcoming chemoresistance in PC.

Interleukin-1β-induced pancreatitis promotes pancreatic ductal adenocarcinoma via B lymphocyte-mediated immune suppression

OBJECTIVE

Long-standing chronic pancreatitis is an established risk factor for pancreatic ductal adenocarcinoma (PDAC). Interleukin-1β (IL-1β) has been associated in PDAC with shorter survival. We employed murine models to investigate the mechanisms by which IL-1β and chronic pancreatitis might contribute to PDAC progression.

DESIGN

We crossed LSL-Kras^+/G12D;Pdx1-Cre (KC) mice with transgenic mice overexpressing IL-1β to generate KC-IL1β mice, and followed them longitudinally. We used pancreatic 3D in vitro culture to assess acinar-to-ductal metaplasia formation. Immune cells were analysed by flow cytometry and immunohistochemical staining. B lymphocytes were adoptively transferred or depleted in Kras-mutant mice. B-cell infiltration was analysed in human PDAC samples.

RESULTS

KC-IL1β mice developed PDAC with liver metastases. IL-1β treatment increased Kras^+/G12D pancreatic spheroid formation. CXCL13 expression and B lymphocyte infiltration were increased in KC-IL1β pancreata. Adoptive transfer of B lymphocytes from KC-IL1β mice promoted tumour formation, while depletion of B cells prevented tumour progression in KC-IL1β mice. B cells isolated from KC-IL1β mice had much higher expression of PD-L1, more regulatory B cells, impaired CD8⁺ T cell activity and promoted tumorigenesis. IL-35 was increased in the KC-IL1β pancreata, and depletion of IL-35 decreased the number of PD-L1⁺ B cells. Finally, in human PDAC samples, patients with PDAC with higher B-cell infiltration within tumours showed significantly shorter survival.

CONCLUSION

We show here that IL-1β promotes tumorigenesis in part by inducing an expansion of immune-suppressive B cells. These findings point to the growing significance of B suppressor cells in pancreatic tumorigenesis.

International consensus guidelines on surveillance for pancreatic cancer in chronic pancreatitis. Recommendations from the working group for the international consensus guidelines for chronic pancreatitis in collaboration with the International Association of Pancreatology, the American Pancreatic Association, the Japan Pancreas Society, and European Pancreatic Club

BACKGROUND

Patients with chronic pancreatitis (CP) have an increased risk of pancreatic cancer. We present the international consensus guidelines for surveillance of pancreatic cancer in CP.

METHODS

The international group evaluated 10 statements generated from evidence on 5 questions relating to pancreatic cancer in CP. The GRADE approach was used to evaluate the level of evidence available per statement. The working group voted on each statement for strength of agreement, using a nine-point Likert scale in order to calculate Cronbach's alpha reliability coefficient.

RESULTS

In the following domains there was strong consensus: (1) the risk of pancreatic cancer in affected individuals with hereditary pancreatitis due to inherited PRSS1 mutations is high enough to justify surveillance; (2) the risk of pancreatic cancer in patients with CP associated with SPINK1 p. N34S is not high enough to justify surveillance; (3) surveillance should be undertaken in pancreatic specialist centers; (4) surveillance should only be introduced after the age of 40 years and stopped when the patient would no longer be suitable for surgical intervention. All patients with CP should be advised to lead a healthy lifestyle aimed at avoiding risk factors for progression of CP and pancreatic cancer. There was only moderate or weak agreement on the best methods of screening and surveillance in other types of environmental, familial and genetic forms of CP.

CONCLUSIONS

Patients with inherited PRSS1 mutations should undergo surveillance for pancreatic cancer, but the best methods for cancer detection need further investigation.

Novel therapeutic strategies and perspectives for metastatic pancreatic cancer: vaccine therapy is more than just a theory

Pancreatic cancer is an aggressive and malignant tumor with an exceedingly high mortality rate. The quality of life and survival rates of pancreatic cancer patients with metastasis are poor compared with those without metastasis. Thus far, no effective treatment strategy has been established for metastatic pancreatic cancer patients. Therefore, an appropriate therapeutic method based on the elimination of metastatic pancreatic cancer is critical to improve patient outcome. Tumor-targeted vaccines have been widely discussed in recent studies and enabled important breakthroughs in the treatment of pancreatic cancer by preventing the escape of tumor cells from immune surveillance and activating the immune system to eliminate cancer cells. T cells can be activated by the stimulation of tumor-targeted vaccines, but to mount an effective immune response, both immune checkpoint inhibitors and positive costimulatory molecules are required. In this review, we discuss potential tumor-targeted vaccines that can target pancreatic cancer, elaborate the probably appropriate combination of vaccines therapy and evaluate the underlying benefits as well as obstacles in the current therapy for metastatic pancreatic cancer.

Deciphering the Role of Protein Kinase D1 (PKD1) in Cellular Proliferation

Protein kinase D1 (PKD1) is a serine/threonine kinase that belongs to the calcium/calmodulin-dependent kinase family, and is involved in multiple mechanisms implicated in tumor progression such as cell motility, invasion, proliferation, protein transport, and apoptosis. While it is expressed in most tissues in the normal state, PKD1 expression may increase or decrease during tumorigenesis, and its role in proliferation is context-dependent and poorly understood. In this review, we present and discuss the current landscape of studies investigating the role of PKD1 in the proliferation of both cancerous and normal cells. Indeed, as a potential therapeutic target, deciphering whether PKD1 exerts a pro- or antiproliferative effect, and under what conditions, is of paramount importance.

Statins and pancreatic cancer risk in patients with chronic pancreatitis: A Danish nationwide population-based cohort study

Statins (HMG-CoA reductase inhibitors) have antiinflammatory and possibly anticancer properties. We hypothesized that statin use is associated with lower risk of pancreatic cancer in patients with chronic pancreatitis. This nationwide population-based cohort study included all Danish patients diagnosed with incident chronic pancreatitis from 1 January 1996 to 31 December 2012. We used the Danish National Prescription Registry to ascertain information on statin prescriptions for members of the study population before and after their pancreatitis diagnosis. We computed crude incidence rates, incidence rate ratios (IRRs) and adjusted hazard ratios (HRs) with associated 95% confidence intervals (CIs) for pancreatic cancer, comparing statin users with nonusers. We computed HRs using Cox proportional hazards regression with statins treated as a time-varying exposure lagged by 1 year, adjusting for age, sex, socioeconomic status and individual comorbidities. The study included 8,311 chronic pancreatitis patients with a median age of 54 years. We observed 153 pancreatic cancers during 60,365 person-years of follow-up. The unadjusted IRR comparing statin users with nonusers was 1.00 (95% CI: 0.60-1.60). Adjustment for potential confounders only had a small impact on the estimate (adjusted HR: 0.90; 95% CI: 0.56-1.44). Our findings suggest that statin use is not associated with pancreatic cancer risk in patients with chronic pancreatitis.

ROBO2 is a stroma suppressor gene in the pancreas and acts via TGF-β signalling

Whereas genomic aberrations in the SLIT-ROBO pathway are frequent in pancreatic ductal adenocarcinoma (PDAC), their function in the pancreas is unclear. Here we report that in pancreatitis and PDAC mouse models, epithelial Robo2 expression is lost while Robo1 expression becomes most prominent in the stroma. Cell cultures of mice with loss of epithelial Robo2 (Pdx1Cre;Robo2F/F) show increased activation of Robo1+ myofibroblasts and induction of TGF-β and Wnt pathways. During pancreatitis, Pdx1Cre;Robo2F/F mice present enhanced myofibroblast activation, collagen crosslinking, T-cell infiltration and tumorigenic immune markers. The TGF-β inhibitor galunisertib suppresses these effects. In PDAC patients, ROBO2 expression is overall low while ROBO1 is variably expressed in epithelium and high in stroma. ROBO2low;ROBO1high patients present the poorest survival. In conclusion, Robo2 acts non-autonomously as a stroma suppressor gene by restraining myofibroblast activation and T-cell infiltration. ROBO1/2 expression in PDAC patients may guide therapy with TGF-β inhibitors or other stroma /immune modulating agents.

CDKN2B deletion is essential for pancreatic cancer development instead of unmeaningful co-deletion due to juxtaposition to CDKN2A

Pancreatic cancer is among the deadliest malignancies; however, the genetic events that lead to pancreatic carcinogenesis in adults remain unclear. In vivo models in which these genetic alterations occur in adult animals may more accurately reflect the features of human cancer. In this study, we demonstrate that inactivation of Cdkn2b (p15ink4b) is necessary for induction of pancreatic cancer by oncogenic KRAS^G12D expression and inactivation of Tp53 and Cdkn2a in adult mouse pancreatic ductal cells (P60 or older). KRAS^G12D overexpression in these cells activated transforming growth factor-β signaling and expression of CDKN2B, which, along with CDKN2A, led to cellular senescence and protected cells from KRAS-mediated transformation via inhibition of retinoblastoma phosphorylation. These results show a critical role of CDKN2B inactivation in pancreatic carcinogenesis, and provide a useful adult animal model by genetic engineering via lentiviral delivery.

Activating transcription factor 3 promotes loss of the acinar cell phenotype in response to cerulein-induced pancreatitis in mice

Pancreatitis is a debilitating disease of the exocrine pancreas that, under chronic conditions, is a major susceptibility factor for pancreatic ductal adenocarcinoma (PDAC). Although down-regulation of genes that promote the mature acinar cell fate is required to reduce injury associated with pancreatitis, the factors that promote this repression are unknown. Activating transcription factor 3 (ATF3) is a key mediator of the unfolded protein response, a pathway rapidly activated during pancreatic insult. Using chromatin immunoprecipitation followed by next-generation sequencing, we show that ATF3 is bound to the transcriptional regulatory regions of >30% of differentially expressed genes during the initiation of pancreatitis. Of importance, ATF3-dependent regulation of these genes was observed only upon induction of pancreatitis, with pathways involved in inflammation, acinar cell differentiation, and cell junctions being specifically targeted. Characterizing expression of transcription factors that affect acinar cell differentiation suggested that acinar cells lacking ATF3 maintain a mature cell phenotype during pancreatitis, a finding supported by maintenance of junctional proteins and polarity markers. As a result, Atf3-/- pancreatic tissue displayed increased tissue damage and inflammatory cell infiltration at early time points during injury but, at later time points, showed reduced acinar-to-duct cell metaplasia. Thus our results reveal a critical role for ATF3 as a key regulator of the acinar cell transcriptional response during injury and may provide a link between chronic pancreatitis and PDAC.

Acinar cell plasticity and development of pancreatic ductal adenocarcinoma

Acinar cells in the adult pancreas show high plasticity and can undergo transdifferentiation to a progenitor-like cell type with ductal characteristics. This process, termed acinar-to-ductal metaplasia (ADM), is an important feature facilitating pancreas regeneration after injury. Data from animal models show that cells that undergo ADM in response to oncogenic signalling are precursors for pancreatic intraepithelial neoplasia lesions, which can further progress to pancreatic ductal adenocarcinoma (PDAC). As human pancreatic adenocarcinoma is often diagnosed at a stage of metastatic disease, understanding the processes that lead to its initiation is important for the discovery of markers for early detection, as well as options that enable an early intervention. Here, the critical determinants of acinar cell plasticity are discussed, in addition to the intracellular and extracellular signalling events that drive acinar cell metaplasia and their contribution to development of PDAC.

Transcriptional Maintenance of Pancreatic Acinar Identity, Differentiation, and Homeostasis by PTF1A

Maintenance of cell type identity is crucial for health, yet little is known of the regulation that sustains the long-term stability of differentiated phenotypes. To investigate the roles that key transcriptional regulators play in adult differentiated cells, we examined the effects of depletion of the developmental master regulator PTF1A on the specialized phenotype of the adult pancreatic acinar cell in vivo Transcriptome sequencing and chromatin immunoprecipitation sequencing results showed that PTF1A maintains the expression of genes for all cellular processes dedicated to the production of the secretory digestive enzymes, a highly attuned surveillance of unfolded proteins, and a heightened unfolded protein response (UPR). Control by PTF1A is direct on target genes and indirect through a ten-member transcription factor network. Depletion of PTF1A causes an imbalance that overwhelms the UPR, induces cellular injury, and provokes acinar metaplasia. Compromised cellular identity occurs by derepression of characteristic stomach genes, some of which are also associated with pancreatic ductal cells. The loss of acinar cell homeostasis, differentiation, and identity is directly relevant to the pathologies of pancreatitis and pancreatic adenocarcinoma.

Animal models of gastrointestinal and liver diseases. Animal models of acute and chronic pancreatitis

Animal models of pancreatitis are useful for elucidating the pathogenesis of pancreatitis and developing and testing novel interventions. In this review, we aim to summarize the most commonly used animal models, overview their pathophysiology, and discuss their strengths and limitations. We will also briefly describe common animal study procedures and refer readers to more detailed protocols in the literature. Although animal models include pigs, dogs, opossums, and other animals, we will mainly focus on rodent models because of their popularity. Autoimmune pancreatitis and genetically engineered animal models will be reviewed elsewhere.

Pathobiology of pancreatic cancer: implications on therapy

Although the concept of tumor heterogeneity was established several decades ago, the interest in this topic is still unbroken. With the identification of inter- and intratumoral genomic rearrangements and the detection of cancer stem cells (CSCs) through phenotypic variations of cancer cells there are increasing options for pancreatic cancer therapy. Indeed, some pre-clinical studies have shown promising results in the treatment of drug-resistant CSCs, whereby a few strategies were already tested in clinical trials. Basically, CSCs are influenced by the tumor microenvironment and an epigenetic reprogramming to gain stem cell-like characteristics. Targeting options inhibiting the epithelial-mesenchymal crosstalk or promoting epigenetic-driven differentiation of CSCs to a less aggressive phenotype raised the possibilities of further therapeutic applications, which will be discussed in this review.

p53 mutations cooperate with oncogenic Kras to promote adenocarcinoma from pancreatic ductal cells

Pancreatic cancer is one of the most lethal malignancies, with virtually all patients eventually succumbing to their disease. Mutations in p53 have been documented in >50% of pancreatic cancers. Owing to the high incidence of p53 mutations in PanIN 3 lesions and pancreatic tumors, we interrogated the comparative ability of adult pancreatic acinar and ductal cells to respond to oncogenic Kras and mutant Tp53(R172H) using Hnf1b:CreER(T2) and Mist1:CreER(T2) mice. These studies involved co-activation of a membrane-tethered GFP lineage label, allowing for direct visualization and isolation of cells undergoing Kras and mutant p53 activation. Kras activation in Mist1(+) adult acinar cells resulted in brisk PanIN formation, whereas no evidence of pancreatic neoplasia was observed for up to 6 months following Kras activation in Hnf1beta(+) adult ductal cells. In contrast to the lack of response to oncogenic Kras alone, simultaneous activation of Kras and mutant p53 in adult ductal epithelium generated invasive PDAC in 75% of mice as early as 2.5 months after tamoxifen administration. These data demonstrate that pancreatic ductal cells, whereas exhibiting relative resistance to oncogenic Kras alone, can serve as an effective cell of origin for pancreatic ductal adenocarcinoma in the setting of gain-of-function mutations in p53.

Elevated miR-483-3p expression is an early event and indicates poor prognosis in pancreatic ductal adenocarcinoma

MiR-483-3p has been reported to be widely involved in diverse human malignancies. However, the exact role of miR-483-3p remains elusive in pancreatic ductal adenocarcinoma (PDAC). The objective of this study is to determine the expression pattern and clinical implications of miR-483-3p in PDAC. MiR-483-3p levels were evaluated by locked nucleic acid-in situ hybridization (LNA-ISH) in a tissue microarray including 63 PDAC tumors and 10 normal pancreatic tissues, followed by evaluation in an independent set of 117 pairs of matched PDAC tumors and adjacent tumor-free pancreatic tissues. Expression of miR-483-3p was further evaluated in pancreatic intra-epithelial neoplasias (PanINs) and chronic pancreatitis (CP). The impact of miR-483-3p on cell proliferation, growth, and anchorage-independent colony formation was also assessed in vitro and in vivo. Microarray analysis revealed that miR-483-3p was positively stained in 61 (96.8 %) PDAC samples, but not detectable in normal pancreatic duct tissue. In the 117 PDAC samples, 100 % were miR-483-3p positive, with 55.6 % (65/117) strongly positive, compared to only 13.7 % (16/117) weakly positive in adjacent normal pancreatic duct tissues. MiR-483-3p expression was associated with tumor grading (p < 0.05) and was an independent predictor of poor overall survival in multivariate analysis (HR = 2.584; 95 % CI = 1.268-5.264). Moreover, from PanIN1 to PanIN3, the rate of strong miR-483-3p-positive staining was 0 % (0/39), 14.8 % (4/27), and 87.5 % (14/16), respectively. Six (54.5 %) CP samples were only weakly stained for miR-483-3p. Inhibition of miR-483-3p suppressed cell proliferation, growth, and colony formation in vitro and decreased tumor cell growth in nude mouse xenografts in vivo. These results suggest that aberrant miR-483-3p expression is an early event in PDAC tumorigenesis and is associated with tumor differentiation and prognosis. It also may be a potential target for PDAC molecular therapeutics.

Deregulation of the MiR-193b-KRAS Axis Contributes to Impaired Cell Growth in Pancreatic Cancer

Modulation of KRAS activity by upstream signals has revealed a promising new approach for pancreatic cancer therapy; however, it is not clear whether microRNA-associated KRAS axis is involved in the carcinogenesis of pancreatic cancer. Here, we identified miR-193b as a tumor-suppressive miRNA in pancreatic ductal adenocarcinoma (PDAC). Expression analyses revealed that miR-193b was downregulated in (10/11) PDAC specimens and cell lines. Moreover, we found that miR-193b functioned as a cell-cycle brake in PDAC cells by inducing G1-phase arrest and reducing the fraction of cells in S phase, thereby leading to dampened cell proliferation. miR-193b also modulated the malignant transformation phenotype of PDAC cells by suppressing anchorage-independent growth. Mechanistically, KRAS was verified as a direct effector of miR-193b, through which the AKT and ERK pathways were modulated and cell growth of PDAC cells was suppressed. Taken together, our findings indicate that miR-193b-mediated deregulation of the KRAS axis is involved in pancreatic carcinogenesis, and suggest that miR-193b could be a potentially effective target for PDAC therapy.

Protein kinase D1 drives pancreatic acinar cell reprogramming and progression to intraepithelial neoplasia

The transdifferentiation of pancreatic acinar cells to a ductal phenotype (acinar-to-ductal metaplasia, ADM) occurs after injury or inflammation of the pancreas and is a reversible process. However, in the presence of activating Kras mutations or persistent epidermal growth factor receptor (EGF-R) signalling, cells that underwent ADM can progress to pancreatic intraepithelial neoplasia (PanIN) and eventually pancreatic cancer. In transgenic animal models, ADM and PanINs are initiated by high-affinity ligands for EGF-R or activating Kras mutations, but the underlying signalling mechanisms are not well understood. Here, using a conditional knockout approach, we show that protein kinase D1 (PKD1) is sufficient to drive the reprogramming process to a ductal phenotype and progression to PanINs. Moreover, using 3D explant culture of primary pancreatic acinar cells, we show that PKD1 acts downstream of TGFα and Kras, to mediate formation of ductal structures through activation of the Notch pathway.

Utilizing past and present mouse systems to engineer more relevant pancreatic cancer models

The study of pancreatic cancer has prompted the development of numerous mouse models that aim to recapitulate the phenotypic and mechanistic features of this deadly malignancy. This review accomplishes two tasks. First, it provides an overview of the models that have been used as representations of both the neoplastic and carcinoma phenotypes. Second, it presents new modeling schemes that ultimately will serve to more faithfully capture the temporal and spatial progression of the human disease, providing platforms for improved understanding of the role of non-epithelial compartments in disease etiology as well as evaluating therapeutic approaches.

Pancreatic cancer and its stroma: A conspiracy theory

Pancreatic cancer is characterised by a prominent desmoplastic/stromal reaction that has received little attention until recent times. Given that treatments focusing on pancreatic cancer cells alone have failed to significantly improve patient outcome over many decades, research efforts have now moved to understanding the pathophysiology of the stromal reaction and its role in cancer progression. In this regard, our Group was the first to identify the cells (pancreatic stellate cells, PSCs) that produced the collagenous stroma of pancreatic cancer and to demonstrate that these cells interacted closely with cancer cells to facilitate local tumour growth and distant metastasis. Evidence is accumulating to indicate that stromal PSCs may also mediate angiogenesis, immune evasion and the well known resistance of pancreatic cancer to chemotherapy and radiotherapy. This review will summarise current knowledge regarding the critical role of pancreatic stellate cells and the stroma in pancreatic cancer biology and the therapeutic approaches being developed to target the stroma in a bid to improve the outcome of this devastating disease.

Galectin-3 and PTEN expression in pancreatic ductal adenocarcinoma, pancreatic neuroendocrine neoplasms and gastrointestinal tumors on fine-needle aspiration cytology

OBJECTIVE

Galectin-3 has been implicated in the carcinogenesis of pancreatic ductal adenocarcinoma (PDAC). Its applicability in pancreatic fine-needle aspiration (FNA) in separating malignant from benign lesions has never been addressed. In addition, a correlation between Galectin-3 and tumor suppressor phosphatase and tensin homolog (PTEN) and their potential diagnostic value has never been tested.

STUDY DESIGN

This study analyzed Galectin-3 immunohistochemical expression in FNA cell blocks of PDAC, pancreatic neuroendocrine neoplasms (PNEN), gastrointestinal stromal tumors (GIST) and non-tumor pancreatic tissue. In parallel, Galectin-3 and PTEN levels were evaluated in a tumor tissue microarray (TMA).

RESULTS

Forty-four of 46 PDAC FNA and 32 of 33 PDAC TMA demonstrated tumor-specific Galectin-3 positivity. In contrast, Galectin-3 was not detected in PNEN and GIST. Total loss of PTEN was displayed by 26 of 33 PDAC, while non-neoplastic tissues all retained PTEN expression.

CONCLUSION

Galectin-3 could be a valuable marker to help diagnose PDAC and rule out PNEN and GIST. In addition, PTEN positivity strongly argues against a diagnosis of PDAC. These data also advocate their potential diagnostic roles in the work up of challenging cytologic cases requiring ancillary test confirmation.

Inflammation to cancer: The molecular biology in the pancreas (Review)

Inflammatory responses are known to be correlated with cancer initiation and progression, and exploration of the route from inflammation to cancer makes a great contribution in elucidating the mechanisms underlying cancer development. Pancreatic cancer (PC) is a lethal disease with a low radical-resection rate and a poor prognosis. As chronic pancreatitis is considered to be a significant etiological factor for PC development, the current review aims to describe the molecular pathways from inflammation to pancreatic carcinogenesis, in support of the strategies for the prevention, diagnosis and treatment of PC.

Pancreatitis-diabetes-pancreatic cancer: summary of an NIDDK-NCI workshop

A workshop sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Cancer Institute (NCI) on "Pancreatitis-Diabetes-Pancreatic Cancer" focused on the risk factors of chronic pancreatitis (CP) and diabetes mellitus (DM) on the development of pancreatic ductal adenocarcinoma (PDAC). Sessions were held on (a) an overview of the problem of PDAC; (b) CP as a risk factor of PDAC; (c) DM as a risk factor of PDAC; (d) pancreatogenic, or type 3c, DM; (e) genomic associations of CP, DM, and PDAC; (f) surveillance of high-risk populations and early detection of PDAC; and (g) effects of DM treatment on PDAC. Recent data and current understandings of the mechanisms of CP- and DM-associated factors on PDAC development were discussed, and a detailed review of the possible risks of DM treatment on the development of PDAC was provided by representatives from academia, industry, and the Food and Drug Administration. The current status of possible biomarkers of PDAC and surveillance strategies for high-risk populations were discussed, and the gaps in knowledge and opportunities for further research were elucidated. A broad spectrum of expertise of the speakers and the discussants provided an unusually productive workshop, the highlights of which are summarized in the accompanying article.

EVI1 oncogene promotes KRAS pathway through suppression of microRNA-96 in pancreatic carcinogenesis

Despite frequent KRAS mutation, the early molecular mechanisms of pancreatic ductal adenocarcinoma (PDAC) development have not been fully elucidated. By tracking a potential regulator of another feature of PDAC precursors, acquisition of foregut or gastric epithelial gene signature, we herein report that aberrant overexpression of ecotropic viral integration site 1 (EVI1) oncoprotein, which is usually absent in normal pancreatic duct, is a widespread marker across the full spectrum of human PDAC precursors and PDAC. In pancreatic cancer cells, EVI1 depletion caused remarkable inhibition of cell growth and migration, indicating its oncogenic roles. Importantly, we found that EVI1 upregulated KRAS expression through suppression of a potent KRAS suppressor, miR-96, in pancreatic cancer cells. Collectively, the present findings suggest that EVI1 overexpression and KRAS mutation converge on activation of the KRAS pathway in early phases of pancreatic carcinogenesis and propose EVI1 and/or miR-96 as early markers and therapeutic targets in this dismal disease.

Complexity of molecular alterations impacts pancreatic cancer prognosis

Individualized cancer treatment (e.g. targeted therapy) based on molecular alterations has emerged as an important strategy to improve the current standard-of-care chemotherapy. A large number of studies have demonstrated the importance of biomarkers not only in predicting prognosis but more importantly in predicting the response towards therapies. For example, amplification or mutation status of the two biomarkers HER2 (human epidermal growth factor 2) and BRCA (breast cancer) can be used to decide on a specific targeted therapy in breast cancer. However, no biomarkers with a similar clinical impact have been identified in pancreatic ductal adenocarcinoma. Although many genome-wide and proteome-based high-throughput studies have identified candidate genes or proteins as promising biomarkers, none of them were eventually transferred into the clinical setting. Notably, the most reliable markers for predicting prognosis are still the tumor stage and grade and biomarkers for therapy response remain undefined. One reason lies in the lack of systemic approaches to analyze the complexity of dominating cancer pathways and the impact of such signal complexity on prognosis and therapy response.

Acting on Hormone Receptors with Minimal Side Effect on Cell Proliferation: A Timely Challenge Illustrated with GLP-1R and GPER

G protein-coupled receptors (GPCRs) constitute a large family of receptors that sense molecules outside the cell and activate inside signal transduction pathways and cellular responses. GPCR are involved in a wide variety of physiological processes, including in the neuroendocrine system. GPCR are also involved in many diseases and are the target of 30% of marketed medicinal drugs. Whereas the majority of the GPCR-targeting drugs have proved their therapeutic benefit, some of them were associated with undesired effects. We develop two examples of used drugs whose therapeutic benefits are tarnished by carcinogenesis risks. The chronic administration of glucagon-like peptide-1 (GLP-1) analogs widely used to treat type-2 diabetes was associated with an increased risk of pancreatic or thyroid cancers. The long-term treatment with the estrogen antagonist tamoxifen, developed to target breast cancer overexpressing estrogen receptors ER, presents agonist activity on the G protein-coupled estrogen receptor which is associated with an increased incidence of endometrial cancer and breast cancer resistance to hormonotherapy. We point out and discuss the need of pharmacological studies to understand and overcome the undesired effects associated with the chronic administration of GPCR ligands. In fact, biological effects triggered by GPCR often result from the activation of multiple intracellular signaling pathways. Deciphering which signaling networks are engaged following GPCR activation appears to be primordial to unveil their contribution in the physiological and physiopathological processes. The development of biased agonists to elucidate the role of the different signaling mechanisms mediated by GPCR activation will allow the generation of new therapeutic agents with improved efficacy and reduced side effects. In this regard, the identification of GLP-1R biased ligands promoting insulin secretion without inducing pro-tumoral effects would offer therapeutic benefit.

Surgery for chronic pancreatitis decreases the risk for pancreatic cancer: a multicenter retrospective analysis

BACKGROUND

Chronic pancreatitis is suggested to be one of the risk factors for the development of pancreatic cancer. The aim of this study was to confirm the high incidence of pancreatic cancer in patients with chronic pancreatitis in Japan and to determine the factors associated with the risk for pancreatic cancer in patients with chronic pancreatitis.

METHODS

The working group of the Research Committee of Intractable Disease supported by the Ministry of Health, Labour and Welfare of Japan carried out a nationwide survey to investigate the relationship between chronic pancreatitis and pancreatic cancer. This retrospective study included patients diagnosed with chronic pancreatitis who had had at least 2 years of follow-up. They were contacted through 22 Japanese referral centers experienced in the management of chronic pancreatitis.

RESULTS

The standardized incidence ratio (95 CI) of pancreatic cancer was 11.8 (7.1-18.4). The incidence of pancreatic cancer was significantly lower in patients who had received surgery for chronic pancreatitis than in those who had not undergone surgery (hazard ratio estimated by Cox regression 0.11; 95% CI, 0.0014-0.80; P = .03). Patients who continued to drink alcohol after diagnosis of chronic pancreatitis showed a significantly higher incidence of pancreatic cancer than those who stopped drinking after diagnosis of chronic pancreatitis (hazard ratio, 5.07; 95% CI, 1.13-22.73; P = .03).

CONCLUSION

This study confirmed that chronic pancreatitis is an important risk factor for the development of pancreatic cancer in Japan. Patients who underwent surgery for the treatment of chronic pancreatitis had significantly lower incidences of pancreatic cancer. Surgery for chronic pancreatitis may inhibit the development of pancreatic cancer in patients with chronic pancreatitis.

Hepatitis B and C virus infections as possible risk factor for pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PAC) is a very aggressive and lethal cancer, with a very poor prognosis, because of absence of early symptoms, advanced stage at presentation, early metastatic dissemination and lack of both specific tests to detect its growth in the initial phases and effective systemic therapies. To date, the causes of PAC still remain largely unknown, but multiple lines of evidence from epidemiological and laboratory researches suggest that about 15-20% of all cancers are linked in some way to chronic infection, in particular it has been shown that several viruses have a role in human carcinogenesis. The purpose of this report is to discuss the hypothesis that two well-known oncogenic viruses, Human B hepatitis (HBV) and Human C hepatitis (HCV) are a possible risk factor for this cancer. Therefore, with the aim to examine the potential link between these viruses and PAC, we performed a selection of observational studies evaluating this association and we hypothesized that some pathogenetic mechanisms involved in liver carcinogenesis might be in common with pancreatic cancer development in patients with serum markers of present or past HBV and HCV infections. To date the available observational studies performed are few, heterogeneous in design as well as in end-points and with not univocal results, nevertheless they might represent the starting-point for future larger and better designed clinical trials to define this hypothesized relationship. Should these further studies confirm an association between HBV/HCV infection and PAC, screening programs might be justified in patients with active or previous hepatitis B and C viral infection.

Exocrine pancreatic carcinogenesis and autotaxin expression

Exocrine pancreatic cancer is an aggressive disease with an exceptionally high mortality rate. Genetic analysis suggests a causative role for environmental factors, but consistent epidemiological support is scarce and no biomarkers for monitoring the effects of chemical pancreatic carcinogens are available. With the objective to identify common traits for chemicals inducing pancreatic tumors we studied the National Toxicology Program (NTP) bioassay database. We found that male rats were affected more often than female rats and identified eight chemicals that induced exocrine pancreatic tumors in males only. For a hypothesis generating process we used a text mining tool to analyse published literature for suggested mode of actions (MOA). The resulting MOA analysis suggested inflammatory responses as common feature. In cell studies we found that all the chemicals increased protein levels of the inflammatory protein autotaxin (ATX) in Panc-1, MIA PaCa-2 or Capan-2 cells. Induction of MMP-9 and increased invasive migration were also frequent effects, consistent with ATX activation. Testosterone has previously been implicated in pancreatic carcinogenesis and we found that it increased ATX levels. Our data show that ATX is a target for chemicals inducing pancreatic tumors in rats. Several lines of evidence implicate ATX and its product lysophosphatidic acid in human pancreatic cancer. Mechanisms of action may include stimulated invasive growth and metastasis. ATX may interact with hormones or onco- or suppressor-genes often deregulated in exocrine pancreatic cancer. Our data suggest that ATX is a target for chemicals promoting pancreatic tumor development.

Overexpressed galectin-3 in pancreatic cancer induces cell proliferation and invasion by binding Ras and activating Ras signaling

Pancreatic cancer (PDAC) is a lethal disease with a five-year survival of 3–5%. Mutations in K-Ras are found in nearly all cases, but K-Ras mutations alone are not sufficient for the development of PDAC. Additional factors contribute to activation of Ras signaling and lead to tumor formation. Galectin-3 (Gal-3), a multifunctional β-galactoside-binding protein, is highly expressed in PDAC. We therefore investigated the functional role of Gal-3 in pancreatic cancer progression and its relationship to Ras signaling. Expression of Gal-3 was determined by immunohistochemistry, Q-PCR and immunoblot. Functional studies were performed using pancreatic cell lines genetically engineered to express high or low levels of Gal-3. Ras activity was examined by Raf pull-down assays. Co-immunoprecipitation and immunofluorescence were used to assess protein-protein interactions. In this study, we demonstrate that Gal-3 was highly up-regulated in human tumors and in a mutant K-Ras mouse model of PDAC. Down-regulation of Gal-3 by lentivirus shRNA decreased PDAC cell proliferation and invasion in vitro and reduced tumor volume and size in an orthotopic mouse model. Gal-3 bound Ras and maintained Ras activity; down-regulation of Gal-3 decreased Ras activity as well as Ras down-stream signaling including phosphorylation of ERK and AKT and Ral A activity. Transfection of Gal-3 cDNA into PDAC cells with low-level Gal-3 augmented Ras activity and its down-stream signaling. These results suggest that Gal-3 contributes to pancreatic cancer progression, in part, by binding Ras and activating Ras signaling. Gal-3 may therefore be a potential novel target for this deadly disease.

An NF-κB pathway-mediated positive feedback loop amplifies Ras activity to pathological levels in mice

Genetic mutations that give rise to active mutant forms of Ras are oncogenic and found in several types of tumor. However, such mutations are not clear biomarkers for disease, since they are frequently detected in healthy individuals. Instead, it has become clear that elevated levels of Ras activity are critical for Ras-induced tumorigenesis. However, the mechanisms underlying the production of pathological levels of Ras activity are unclear. Here, we show that in the presence of oncogenic Ras, inflammatory stimuli initiate a positive feedback loop involving NF-κB that further amplifies Ras activity to pathological levels. Stimulation of Ras signaling by typical inflammatory stimuli was transient and had no long-term sequelae in wild-type mice. In contrast, these stimuli generated prolonged Ras signaling and led to chronic inflammation and precancerous pancreatic lesions (PanINs) in mice expressing physiological levels of oncogenic K-Ras. These effects of inflammatory stimuli were disrupted by deletion of inhibitor of NF-κB kinase 2 (IKK2) or inhibition of Cox-2. Likewise, expression of active IKK2 or Cox-2 or treatment with LPS generated chronic inflammation and PanINs only in mice expressing oncogenic K-Ras. The data support the hypothesis that in the presence of oncogenic Ras, inflammatory stimuli trigger an NF-κB-mediated positive feedback mechanism involving Cox-2 that amplifies Ras activity to pathological levels. Because a large proportion of the adult human population possesses Ras mutations in tissues including colon, pancreas, and lung, disruption of this positive feedback loop may be an important strategy for cancer prevention.

Acute pancreatitis accelerates initiation and progression to pancreatic cancer in mice expressing oncogenic Kras in the nestin cell lineage

Targeting of oncogenic Kras to the pancreatic Nestin-expressing embryonic progenitor cells and subsequently to the adult acinar compartment and Nestin-expressing cells is sufficient for the development of low grade pancreatic intraepithelial neoplasia (PanIN) between 2 and 4 months. The mice die around 6 month-old of unrelated causes, and it is therefore not possible to assess whether the lesions will progress to carcinoma. We now report that two brief episodes of caerulein-induced acute pancreatitis in 2 month-old mice causes rapid PanIN progression and pancreatic ductal adenocarcinoma (PDAC) development by 4 months of age. These events occur with similar frequency as observed in animals where the oncogene is targeted during embryogenesis to all pancreatic cell types. Thus, these data show that oncogenic Kras-driven PanIN originating in a non-ductal compartment can rapidly progress to PDAC when subjected to a brief inflammatory insult.

Pancreatic cancer in chronic pancreatitis; aetiology, incidence, and early detection

Acute pancreatitis, chronic pancreatitis and pancreatic cancer are responsible for most of the burden of exocrine pancreatic disease. Glandular damage from recurrent bouts of acute pancreatitis can lead to irreversible changes characteristic of chronic pancreatitis. In recent decades accumulating evidence has defined longstanding pre-existing chronic pancreatitis as a strong risk factor for pancreatic cancer. The lag period between diagnosis of chronic pancreatitis and pancreatic cancer is usually one or two decades: pancreatitis appearing a year or two before the diagnosis of pancreatic cancer is often the result of tumour-related ductal obstruction. The risk of developing pancreatic cancer appears to be highest in rare types of pancreatitis with an early onset, such as hereditary pancreatitis and tropical pancreatitis. Even though there is a strong link between chronic pancreatitis and pancreatic cancer, over a 20 year period only around five percent of patients with chronic pancreatitis will develop pancreatic cancer. Until the development of more sophisticated screening procedures, screening is not recommended for patients with chronic pancreatitis.