Phenotype screens of murine pancreatic cancer identify a Tgf-α-Ccl2-paxillin axis driving human-like neural invasion

Solid cancers like pancreatic ductal adenocarcinoma (PDAC), a type of pancreatic cancer, frequently exploit nerves for rapid dissemination. This neural invasion (NI) is an independent prognostic factor in PDAC, but insufficiently modeled in genetically engineered mouse models (GEMM) of PDAC. Here, we systematically screened for human-like NI in Europe's largest repository of GEMM of PDAC, comprising 295 different genotypes. This phenotype screen uncovered 2 GEMMs of PDAC with human-like NI, which are both characterized by pancreas-specific overexpression of transforming growth factor α (TGF-α) and conditional depletion of p53. Mechanistically, cancer-cell-derived TGF-α upregulated CCL2 secretion from sensory neurons, which induced hyperphosphorylation of the cytoskeletal protein paxillin via CCR4 on cancer cells. This activated the cancer migration machinery and filopodia formation toward neurons. Disrupting CCR4 or paxillin activity limited NI and dampened tumor size and tumor innervation. In human PDAC, phospho-paxillin and TGF-α-expression constituted strong prognostic factors. Therefore, we believe that the TGF-α-CCL2-CCR4-p-paxillin axis is a clinically actionable target for constraining NI and tumor progression in PDAC.

Abstract PR003: Fibroblast plasticity driven by Prrx1 interferes the tumor cells - tumor microenvironment crosstalk towards a more aggressive pancreatic ductal adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a fibroblast-rich desmoplastic stroma which plays a critical role in the progression and therapeutic resistance of PDAC. The stroma is composed of extracellular matrix proteins, mainly deposited by the cancer-associated-fibroblasts (CAFs) and various types of immune cells. Cancer-associated fibroblasts display a high degree of interconvertible states including quiescent, inflammatory and myofibroblastic phenotypes. However, the mechanisms by which this plasticity is achieved are poorly understood. Here, we demonstrate that CAF plasticity promotes PDAC cell aggressiveness through multiple mechanism, particularly promoting Epithelial-to-Mesenchymal Transition and immune cell infiltration.

Methods: To manipulate fibroblast plasticity in PDAC, we generated genetically engineered mouse models (GEMMs) in which CAF plasticity is modulated by genetical depletion of the transcription factor Prrx1 in fibroblasts by using orthotopic implantation models (Sm22-CreERT, Prrx1fl/fl, Rosa26mTmG) as well as dual recombinase-driven GEMMs (Pdx-Flp, FSF-KrasG12D/w t, p53fr/wtt, Sm22-CreERT, Prrx1fl/fl). To characterize the impact of CAFs on tumor differentiation, immune cell infiltration and response to chemotherapy various in vivo and in vitro co-culture experiments were performed.

Results: Our in vivo results demonstrate that restraining CAF plasticity by Prrx1-depletion leads to more differentiated tumors, disrupts systemic tumor dissemination, including circulating tumor cells as well as metastases. Interestingly in tumors with Prrx1-deficient stroma, infiltration of macrophages and lymphocytes was increased. Specifically, we observed more B-cells as well as cytotoxic T-cells. Gene expression profiling of primary murine fibroblast samples revealed that Prrx1-deficient CAFs express myofibroblastic gene signatures characterized by ECM secretion phenotype. Indeed, on a functional level Prrx1-deficient CAFs secret more collagen and are highly migratory. Additionally, co-culture experiments of tumor cells and CAFs revealed that Prrx1-driven CAF-derived hepatocyte growth factor confers to a more invasive PDAC cell phenotype and resistant to therapy-induced apoptosis by inducing EMT in vitro. Importantly, in line with our in vitro and in vivo findings, compartment specific-gene expression analysis of human data revealed that pancreatic cancer patients with high stromal expression of Prrx1 display the squamous, most aggressive, subtype of PDAC.

Conclusions: Here, we define that the Prrx1 transcription factor is critical for CAF plasticity, allowing a dynamic switch between different states. This work demonstrates that Prrx1-mediated CAF plasticity has significant impact on PDAC biology and therapeutic resistance.

Citation Format: Karin Feldmann, Carlo Maurer, Katja Peschke, Steffen Teller, Kathleen Schuck, Katja Steiger, Thomas Engleitner, Rupert Öllinger, Aristeidis Papargyriou, Rim Sabrina Jahan Sarker, Wilko Weichert, Anil K. Rustgi, Roland M. Schmid, Roland Rad, Günter Schneider, Dieter Saur, Maximilian Reichert. Fibroblast plasticity driven by Prrx1 interferes the tumor cells - tumor microenvironment crosstalk towards a more aggressive pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PR003.

Mesenchymal Plasticity Regulated by Prrx1 Drives Aggressive Pancreatic Cancer Biology

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a fibroblast-rich desmoplastic stroma. Cancer-associated fibroblasts (CAFs) have been shown to display a high degree of interconvertible states including quiescent, inflammatory, and myofibroblastic phenotypes; however, the mechanisms by which this plasticity is achieved are poorly understood. Here, we aim to elucidate the role of CAF plasticity and its impact on PDAC biology.

METHODS

To investigate the role of mesenchymal plasticity in PDAC progression, we generated a PDAC mouse model in which CAF plasticity is modulated by genetic depletion of the transcription factor Prrx1. Primary pancreatic fibroblasts from this mouse model were further characterized by functional in vitro assays. To characterize the impact of CAFs on tumor differentiation and response to chemotherapy, various coculture experiments were performed. In vivo, tumors were characterized by morphology, extracellular matrix composition, and tumor dissemination and metastasis.

RESULTS

Our in vivo findings showed that Prrx1-deficient CAFs remain constitutively activated. Importantly, this CAF phenotype determines tumor differentiation and disrupts systemic tumor dissemination. Mechanistically, coculture experiments of tumor organoids and CAFs showed that CAFs shape the epithelial-to-mesenchymal phenotype and confer gemcitabine resistance of PDAC cells induced by CAF-derived hepatocyte growth factor. Furthermore, gene expression analysis showed that patients with pancreatic cancer with high stromal expression of Prrx1 display the squamous, most aggressive, subtype of PDAC.

CONCLUSIONS

Here, we define that the Prrx1 transcription factor is critical for tuning CAF activation, allowing a dynamic switch between a dormant and an activated state. This work shows that Prrx1-mediated CAF plasticity has significant impact on PDAC biology and therapeutic resistance.

Indirect cholinergic activation slows down pancreatic cancer growth and tumor-associated inflammation

Background

Nerve-cancer interactions are increasingly recognized to be of paramount importance for the emergence and progression of pancreatic cancer (PCa). Here, we investigated the role of indirect cholinergic activation on PCa progression through inhibition of acetylcholinesterase (AChE) via clinically available AChE-inhibitors, i.e. physostigmine and pyridostigmine.

Methods

We applied immunohistochemistry, immunoblotting, MTT-viability, invasion, flow-cytometric-cell-cycle-assays, phospho-kinase arrays, multiplex ELISA and xenografted mice to assess the impact of AChE inhibition on PCa cell growth and invasiveness, and tumor-associated inflammation. Survival analyses were performed in a novel genetically-induced, surgically-resectable mouse model of PCa under adjuvant treatment with gemcitabine+/−physostigmine/pyridostigmine (n = 30 mice). Human PCa specimens (n = 39) were analyzed for the impact of cancer AChE expression on tumor stage and survival.

Results

We discovered a strong expression of AChE in cancer cells of human PCa specimens. Inhibition of this cancer-cell-intrinsic AChE via pyridostigmine and physostigmine, or administration of acetylcholine (ACh), diminished PCa cell viability and invasion in vitro and in vivo via suppression of pERK signaling, and reduced tumor-associated macrophage (TAM) infiltration and serum pro-inflammatory cytokine levels. In the novel genetically-induced, surgically-resectable PCa mouse model, adjuvant co-therapy with AChE blockers had no impact on survival. Accordingly, survival of resected PCa patients did not differ based on tumor AChE expression levels. Patients with higher-stage PCa also exhibited loss of the ACh-synthesizing enzyme, choline-acetyltransferase (ChAT), in their nerves.

Conclusion

For future clinical trials of PCa, direct cholinergic stimulation of the muscarinic signaling, rather than indirect activation via AChE blockade, may be a more effective strategy.

Localisation analysis of nerves in the mouse pancreas reveals the sites of highest nerve density and nociceptive innervation

BACKGROUND

Neuropathy and neuro-inflammation drive the severe pain and disease progression in human chronic pancreatitis and pancreatic cancer. Mice, especially genetically induced-mouse models, have been increasingly utilized in mechanistic research on pancreatic neuropathy, but the normal "peripheral neurobiology" of the mouse pancreas has not yet been critically compared to human pancreas.

METHODS

We introduced a standardized tissue-harvesting technique that preserves the anatomic orientation of the mouse pancreas and allows complete sectioning in an anterior to posterior fashion. We applied immunohistochemistry and quantitative colorimetry of all nerves from the whole organ for studying pancreatic neuro-anatomy.

KEY RESULTS

Nerves in the mouse pancreas appeared as "clusters" of nerve trunks in contrast to singly distributed nerve trunks in the human pancreas. Nerve trunks in the mouse pancreas were exclusively found around intrapancreatic blood vessels, and around lymphoid structures. The majority of nerve trunks were located in the pancreatic head (0.15 ± 0.08% of tissue area) and the anterior/front surface of the corpus/body (0.17 ± 0.27%), thus significantly more than in the tail (0.02 ± 0.02%, P = .006). Nerves in the tail included a higher proportion of nociceptive fibers, but the absolute majority, ie, ca. 70%, of all nociceptive fibers, were localized in the head. Mice heterozygous for Bdnf knockout allele (Bdnf^+/- ) exhibited enrichment of nitrergic nerve fibers specifically in the head and corpus.

CONCLUSIONS & INFERENCES

Neuro-anatomy of the "mesenteric type" mouse pancreas is highly different from the "compact" human pancreas. Studies that aim at reproducing human pancreatic neuro-phenomena in mouse models should pay diligent attention to these anatomic differences.

Neoadjuvant Therapy Remodels the Pancreatic Cancer Microenvironment via Depletion of Protumorigenic Immune Cells

PURPOSE

Neoadjuvant therapy (neoTx) has dramatically improved the prognosis of patients with locally advanced and borderline resectable pancreatic ductal adenocarcinoma, yet its mechanisms of action on tumor cells and the tumor microenvironment are still unknown. Here, we aimed to characterize the multiple facets of neoTx-induced alterations in the pancreatic cancer microenvironment.

EXPERIMENTAL DESIGN

We performed the currently most comprehensive histopathologic analysis of desmoplasia, angiogenesis, neural invasion, and immune cell infiltration at the tumor-host interface of pancreatic cancer after neoTx (n = 37) versus after primary resection (n = 37) through quantitative IHC and double immunofluorescence using automated and software-based quantification algorithms.

RESULTS

We demonstrate that, independently of the applied pretreatment, neoadjuvant regimes are able to reverse the immunosuppressive behavior of malignant cells on pancreatic cancer microenvironment. Here, neoTx-driven selective depletion of regulatory T cells and myeloid-derived suppressor cells was associated with enrichment of antitumor immune cells in the peritumoral niche, decreased stromal activation, and less neural invasion. Importantly, the degree of this antitumor immune remodeling correlates to the degree of histopathologic response to neoTx. Survival analysis revealed that the tumor proliferation rate together with the activation of the stroma and the intratumoral infiltration with CD4⁺ T cells and natural killer cells constitute as independent prognostic factors for neoadjuvantly treated pancreatic cancer.

CONCLUSIONS

NeoTx is not only cytotoxic but has pleiotropic, beneficial effects on all cellular and noncellular components of pancreatic cancer. Combinational approaches including immunotherapy may unleash long-term and more effective antitumor responses and improve prognosis of pancreatic cancer.

Targeting nNOS ameliorates the severe neuropathic pain due to chronic pancreatitis

BACKGROUND

Pain due to pancreatic cancer/PCa or chronic pancreatitis/CP, is notoriously resistant to the strongest pain medications. Here, we aimed at deciphering the specific molecular mediators of pain at surgical-stage pancreatic disease and to discover novel translational targets.

METHODS

We performed a systematic, quantitative analysis of the neurotransmitter/neuroenzmye profile within intrapancreatic nerves of CP and PCa patients. Ex vivo neuronal cultures treated with human pancreatic extracts, conditional genetically engineered knockout mouse models of PCa and CP, and the cerulein-induced CP model were employed to explore the therapeutic potential of the identified targets.

FINDINGS

We identified a unique enrichment of neuronal nitric-oxide-synthase (nNOS) in the pancreatic nerves of CP patients with increasing pain severity. Employment of ex vivo neuronal cultures treated with pancreatic tissue extracts of CP patients, and brain-derived-neurotrophic-factor-deficient (BDNF^+/-) mice revealed neuronal enrichment of nNOS to be a consequence of BDNF loss in the progressively destroyed pancreatic tissue. Mechanistically, nNOS upregulation in sensory neurons was induced by tryptase secreted from perineural mast cells. In a head-to-head comparison of several genetically induced, painless mouse models of PCa (KPC, KC mice) or CP (Ptf1a-Cre;Atg5^fl/fl) against the hypersecretion/cerulein-induced, painful CP mouse model, we show that a similar nNOS enrichment is present in the painful cerulein-CP model, but absent in painless genetic models. Consequently, mice afflicted with painful cerulein-induced CP could be significantly relieved upon treatment with the specific nNOS inhibitor NPLA.

INTERPRETATION

We propose nNOS inhibition as a novel strategy to treat the unbearable pain in CP. FUND: Deutsche Forschungsgemeinschaft/DFG (DE2428/3-1 and 3-2).

Genetically induced vs. classical animal models of chronic pancreatitis: a critical comparison

Chronic pancreatitis (CP) is an utmost complex disease that is pathogenetically linked to pancreas-intrinsic ( e.g., duct obstruction), environmental-toxic ( e.g., alcohol, smoking), and genetic factors. Studying such a complex disease naturally requires validated experimental models. In the past 2 decades, the various animal models of CP usually addressed either the pancreas-intrinsic ( e.g., the caerulein model), the environmental-toxic ( e.g., diet-induced models), or the genetic component of CP. As such, these models were far from mirroring CP in its full spectrum, and the correct choice of models was vital for valid scientific conclusions on CP. The quest for mechanistic, genetic models gave rise to models based on gene modification and transgene insertion, such as the PRSS1 and the IL-1β/IL-1β models. Recently, we witnessed the development of highly exciting models that rely on the importance of autophagy in CP, that is, the murine pancreas-specific Atg5 and LAMP2 knockout models. Today, critical comparison of these several models is more important than ever for guiding research on CP in an efficient direction. The present review outlines the characteristics of the new genetic models in comparison with the well-known classic models for CP, notes the caveats in the choice of models, and also indicates novel directions for model development.-Klauss, S., Schorn, S., Teller, S., Steenfadt, H., Friess, H., Ceyhan, G. O., Demir, I. K. Genetically induced vs. classical animal models of chronic pancreatitis: a critical comparison.

3D Cancer Migration Assay with Schwann Cells

In pancreatic cancer, neural invasion is one of the most common paths of cancer dissemination. Classically, cancer cells actively invade nerves and cause local recurrence and pain. Three-dimensional (3D) neural migration assay has become a standard tool for scientists to study neural invasion by confronting the involved cell types. This protocol introduces Schwann cells, i.e., the most prevalent cell type in peripheral nerves, in a novel heterotypic, glia-cancer-neuron, 3D migration assay for assessing their relevance in the early pathogenesis of neural invasion. Particularly, this assay allows the monitoring of the early Schwann cell migratory activity.

Tumour-specific delivery of siRNA-coupled superparamagnetic iron oxide nanoparticles, targeted against PLK1, stops progression of pancreatic cancer

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies and is projected to be the second leading cause of cancer-related death by 2030. Despite extensive knowledge and insights into biological properties and genetic aberrations of PDAC, therapeutic options remain temporary and ineffective. One plausible explanation for the futile response to therapy is an insufficient and non-specific delivery of anticancer drugs to the tumour site.

DESIGN

Superparamagnetic iron oxide nanoparticles (SPIONs) coupled with siRNA directed against the cell cycle-specific serine-threonine-kinase, Polo-like kinase-1 (siPLK1-StAv-SPIONs), could serve a dual purpose for delivery of siPLK1 to the tumour and for non-invasive assessment of efficiency of delivery in vivo by imaging the tumour response. siPLK1-StAv-SPIONs were designed and synthesised as theranostics to function via a membrane translocation peptide with added advantage of driving endosomal escape for mediating transportation to the cytoplasm (myristoylated polyarginine peptides) as well as a tumour-selective peptide (EPPT1) to increase intracellular delivery and tumour specificity, respectively.

RESULTS

A syngeneic orthotopic as well as an endogenous cancer model was treated biweekly with siPLK1-StAv-SPIONs and tumour growth was monitored by small animal MRI. In vitro and in vivo experiments using a syngeneic orthotopic PDAC model as well as the endogenous LSL-KrasG12D, LSL-Trp53R172H, Pdx-1-Cre model revealed significant accumulation of siPLK1-StAv-SPIONs in PDAC, resulting in efficient PLK1 silencing. Tumour-specific silencing of PLK1 halted tumour growth, marked by a decrease in tumour cell proliferation and an increase in apoptosis.

CONCLUSIONS

Our data suggest siPLK1-StAv-SPIONs with dual specificity residues for tumour targeting and membrane translocation to represent an exciting opportunity for targeted therapy in patients with PDAC.

Activated Schwann cells in pancreatic cancer are linked to analgesia via suppression of spinal astroglia and microglia

OBJECTIVE

The impact of glia cells during GI carcinogenesis and in cancer pain is unknown. Here, we demonstrate a novel mechanism how Schwann cells (SCs) become activated in the pancreatic cancer (PCa) microenvironment and influence spinal activity and pain sensation.

DESIGN

Human SCs were exposed to hypoxia, to pancreatic cancer cells (PCCs) and/or to T-lymphocytes. Both SC and intrapancreatic nerves of patients with PCa with known pain severity were assessed for glial intermediate filament and hypoxia marker expression, proliferation and for transcriptional alterations of pain-related targets. In conditional PCa mouse models with selective in vivo blockade of interleukin (IL)-6 signalling (Ptf1a-Cre;LSL-Kras(G12D)/KC interbred with IL6(-/-) or sgp130(tg) mice), SC reactivity, abdominal mechanosensitivity and spinal glial/neuronal activity were quantified.

RESULTS

Tumour hypoxia, PCC and/or T-lymphocytes activated SC via IL-6-signalling in vitro. Blockade of the IL-6-signalling suppressed SC activation around PCa precursor lesions (pancreatic intraepithelial neoplasia (PanIN)) in KC;IL6(-/-) (32.06%±5.25% of PanINs) and KC;sgp130(tg) (55.84%±5.51%) mouse models compared with KC mice (78.27%±3.91%). Activated SCs were associated with less pain in human PCa and with decreased abdominal mechanosensitivity in KC mice (von Frey score of KC: 3.9±0.5 vs KC;IL6(-/-) mice: 5.9±0.9; and KC;sgp130(tg): 10.21±1.4) parallel to attenuation of spinal astroglial and/or microglial activity. Activated SC exhibited a transcriptomic profile with anti-inflammatory and anti-nociceptive features.

CONCLUSIONS

Activated SC in PCa recapitulate the hallmarks of 'reactive gliosis' and contribute to analgesia due to suppression of spinal glia. Our findings propose a mechanism for how cancer might remain pain-free via the SC-central glia interplay during cancer progression.

Investigation of Schwann cells at neoplastic cell sites before the onset of cancer invasion

BACKGROUND

In neural invasion (NI), cancer cells are classically assumed to actively invade nerves and to cause local recurrence and pain. However, the opposite possibility, that nerves may reach cancer cells even in their preinvasive stage and thereby promote cancer spread, has not yet been genuinely considered. The present study analyzes the reaction of Schwann cells of peripheral nerves to carcinogenesis in pancreatic cancer and colon cancer.

METHODS

Two novel 3D migration and Schwann cell outgrowth assays were developed to monitor the timing and the specificity of Schwann cell migration and cancer invasion toward peripheral neurons through digital-time-lapse microscopy and after blockade of nerve growth factor (NGF) signalling via siRNA or a small-molecule inhibitor of the p75(NTR) receptor. The frequency and emergence of the Schwann cell markers Sox10, S100, ALDH1L1, and glial-fibrillary-acidic-protein (GFAP) around cancer precursor lesions were studied in human and conditional murine pancreatic and colon cancer specimens using multiple immunolabeling.

RESULTS

Schwann cells migrated toward pancreatic and colon cancer cells, but not toward benign cells, before the onset of cancer migration toward peripheral neurons. This chemoattraction was inhibited after blockade of p75(NTR)-signaling on Schwann and pancreatic cancer cells. Schwann cells were specifically detected around murine and human pancreatic intraepithelial neoplasias (PanINs) (mean percent of murine PanINs surrounded by Schwann cells = 78.9%, 95% CI = 70.9 to 86.8%, and mean percent of human PanINs surrounded by Schwann cells = 52.5%, 95% CI = 14.7 to 90.4%; human: n = 44, murine: n = 14) and intestinal adenomas (mean percent of murine adenomas surrounded by Schwann cells = 64.2%, 95% CI = 28.6 to 99.8%, and mean percent of human adenomas surrounded by Schwann cells = 17.2%, 95% CI = -126.9 to 161.4; human: n = 36, murine: n = 12). The Schwann cell presence in this premalignant stage was associated with the frequency of NI in the malignant phase.

CONCLUSIONS

Schwann cells have particular and specific affinity to cancer cells. Emergence of Schwann cells in the premalignant phase of pancreatic and colon cancer implies that, in contrast with the traditional assumption, nerves-and not cancer cells-migrate first during NI.

Association analysis of genetic variants in the myosin IXB gene in acute pancreatitis

INTRODUCTION

Impairment of the mucosal barrier plays an important role in the pathophysiology of acute pancreatitis. The myosin IXB (MYO9B) gene and the two tight-junction adaptor genes, PARD3 and MAGI2, have been linked to gastrointestinal permeability. Common variants of these genes are associated with celiac disease and inflammatory bowel disease, two other conditions in which intestinal permeability plays a role. We investigated genetic variation in MYO9B, PARD3 and MAGI2 for association with acute pancreatitis.

METHODS

Five single nucleotide polymorphisms (SNPs) in MYO9B, two SNPs in PARD3, and three SNPs in MAGI2 were studied in a Dutch cohort of 387 patients with acute pancreatitis and over 800 controls, and in a German cohort of 235 patients and 250 controls.

RESULTS

Association to MYO9B and PARD3 was observed in the Dutch cohort, but only one SNP in MYO9B and one in MAGI2 showed association in the German cohort (p < 0.05). Joint analysis of the combined cohorts showed that, after correcting for multiple testing, only two SNPs in MYO9B remained associated (rs7259292, p = 0.0031, odds ratio (OR) 1.94, 95% confidence interval (95% CI) 1.35-2.78; rs1545620, p = 0.0006, OR 1.33, 95% CI 1.16-1.53). SNP rs1545620 is a non-synonymous SNP previously suspected to impact on ulcerative colitis. None of the SNPs showed association to disease severity or etiology.

CONCLUSION

Variants in MYO9B may be involved in acute pancreatitis, but we found no evidence for involvement of PARD3 or MAGI2.

Differential roles of inflammatory cells in pancreatitis

The incidence of acute pancreatitis per 100,000 of population ranges from 5 to 80. Patients suffering from hemorrhagic-necrotizing pancreatitis die in 10-24% of cases. 80% of all cases of acute pancreatitis are etiologically linked to gallstone disease immoderate alcohol consumption. As of today no specific causal treatment for acute pancreatitis exists. Elevated C-reactive protein levels above 130,mg/L can also predict a severe course of acute pancreatitis. The essential medical treatment for acute pancreatitis is the correction of hypovolemia. Prophylactic antibiotics should be restricted to patients with necrotizing pancreatitis, infected necrosis or other infectious complications. However, as premature intracellular protease activation is known to be the primary event in acute pancreatitis. Severe acute pancreatitis is characterized by an early inflammatory immune response syndrome (SIRS) and a subsequent compensatory anti-inflammatory response syndrome (CARS) contributing to severity as much as protease activation does. CARS suppresses the immune system and facilitates nosocomial infections including infected pancreatic necrosis, one of the most feared complications of the disease. A number of attempts have been made to suppress the early systemic inflammatory response but even if these mechanisms have been found to be beneficial in animal models they failed in daily clinical practice.

Phosphoproteomic identification of a PDX-1/14-3-3ε interaction in pancreatic beta cells

Glucose-dependent activation of the homeodomain transcription factor PDX-1 leads to its phosphorylation, to an increase in DNA binding capacity, and to NLS dependent translocation into the nucleus. To uncover unknown mediators of PDX-1 activation, PDX-1 interacting proteins were analysed by pull-down from (32)P-labelled, glucose-stimulated MIN6 cells. Recovered proteins were analysed by 2D gel electrophoresis and mass spectrometry. We identified 14-3-3ε as a novel PDX-1 binding protein and confirmed the interaction in vivo by Fluorescence Resonance Energy Transfer (FRET) analysis. We propose that 14-3-3ε interacts directly with PDX-1 to regulate its cellular distribution in pancreatic beta cells.

Integrin-mediated cell attachment induces a PAK4-dependent feedback loop regulating cell adhesion through modified integrin alpha v beta 5 clustering and turnover

Cell-to-extracellular matrix adhesion is regulated by a multitude of pathways initiated distally to the core cell-matrix adhesion machinery, such as via growth factor signaling. In contrast to these extrinsically sourced pathways, we now identify a regulatory pathway that is intrinsic to the core adhesion machinery, providing an internal regulatory feedback loop to fine tune adhesion levels. This autoinhibitory negative feedback loop is initiated by cell adhesion to vitronectin, leading to PAK4 activation, which in turn limits total cell-vitronectin adhesion strength. Specifically, we show that PAK4 is activated by cell attachment to vitronectin as mediated by PAK4 binding partner integrin αvβ5, and that active PAK4 induces accelerated integrin αvβ5 turnover within adhesion complexes. Accelerated integrin turnover is associated with additional PAK4-mediated effects, including inhibited integrin αvβ5 clustering, reduced integrin to F-actin connectivity and perturbed adhesion complex maturation. These specific outcomes are ultimately associated with reduced cell adhesion strength and increased cell motility. We thus demonstrate a novel mechanism deployed by cells to tune cell adhesion levels through the autoinhibitory regulation of integrin adhesion.

Cathepsin L inactivates human trypsinogen, whereas cathepsin L-deletion reduces the severity of pancreatitis in mice

BACKGROUND & AIMS

Acute pancreatitis is characterized by an activation cascade of digestive enzymes in the pancreas. The first of these, trypsinogen, can be converted to active trypsin by the peptidase cathepsin B (CTSB). We investigated whether cathepsin L (CTSL) can also process trypsinogen to active trypsin and has a role in pancreatitis.

METHODS

In CTSL-deficient (Ctsl(-/-)) mice, pancreatitis was induced by injection of cerulein or infusion of taurocholate into the pancreatic duct. Human tissue, pancreatic juice, mouse pancreatitis specimens, and recombinant enzymes were studied by enzyme assay, immunoblot, N-terminal sequencing, immunocytochemistry, and electron microscopy analyses. Isolated acini from Ctsl(-/-) and Ctsb(-/-) mice were studied.

RESULTS

CTSL was expressed in human and mouse pancreas, colocalized with trypsinogen in secretory vesicles and lysosomes, and secreted into pancreatic juice. Severity of pancreatitis was reduced in Ctsl(-/-) mice, whereas apoptosis and intrapancreatic trypsin activity were increased. CTSL-induced cleavage of trypsinogen occurred 3 amino acids toward the C-terminus from the CTSB activation site and resulted in a truncated, inactive form of trypsin and an elongated propeptide (trypsinogen activation peptide [TAP]). This elongated TAP was not detected by enzyme-linked immunosorbent assay (ELISA) but was effectively converted to an immunoreactive form by CTSB. Levels of TAP thus generated by CTSB were not associated with disease severity, although this is what the TAP-ELISA is used to determine in the clinic.

CONCLUSIONS

CTSL inactivates trypsinogen and counteracts the ability of CTSB to form active trypsin. In mouse models of pancreatitis, absence of CTSL induces apoptosis and reduces disease severity.

Altered expression of tumor protein D52 regulates apoptosis and migration of prostate cancer cells

Tumor protein D52 (TPD52) is a protein found to be overexpressed in prostate and breast cancer due to gene amplification. However, its physiological function remains under investigation. In the present study, we investigated the response of the LNCaP human prostate carcinoma cell line to deregulation of TPD52 expression. Proteomic analysis of prostate biopsies showed TPD52 overexpression at the protein level, whereas its transcriptional upregulation was demonstrated by real-time PCR. Transfection of LNCaP cells with a specific small hairpin RNA giving efficient knockdown of TPD52 resulted in significant cell death of the carcinoma LNCaP cells. As demonstrated by activation of caspases (caspase-3 and -9), and by the loss of mitochondrial membrane potential, cell death occurs due to apoptosis. The disruption of the mitochondrial membrane potential indicates that TPD52 acts upstream of the mitochondrial apoptotic reaction. To study the effect of TPD52 expression on cell proliferation, LNCaP cells were either transfected with enhanced green fluorescence protein-TPD52 or a specific small hairpin RNA. Enhanced green fluorescence protein-TPD52 overexpressing cells showed an increased proliferation rate, whereas TPD52-depleted cells showed the reverse effect. Additionally, we demonstrate that exogenous expression of TPD52 promotes cell migration via alphav beta3 integrin in prostate cancer cells through activation of the protein kinase B/Akt signaling pathway. From these results, we conclude that TPD52 plays an important role in various molecular events, particularly in the morphological diversification and dissemination of prostate carcinoma cells, and may be a promising target with respect to developing new therapeutic strategies to treat prostate cancer.

[Clinical accuracy of fluoroscopic navigation at the thoracic and lumbar spine]

The aim of the present study was the verification of the accuracy of 2-D fluoroscopy-based navigated pedicle screws at the thoracic and lumbar spine in a case series of traumatised patients. Within 36 months 111 pedicle screws in 29 patients were instrumented using C-arm based navigation, 60 at the thoracic and 51 at the lumbar spine. All screw positions were evaluated postoperatively by a routine thin slice CT scan using multiplanar reconstruction. The position of a screw in relation to its pedicle was classified in a) screw completely intraosseous, b) screw perforated less than thread level and c) screw perforated more than thread level. In 34 thoracic (56.7%) and 32 lumbar (62.7%) screws complete intraosseous placement was observed, 14 thoracic (23.3%) and 14 lumbar (27.5%) screws perforated less than thread level. Perforations more than thread level were found in 12 thoracic (20%) and 5 lumbar (9.8%) screws. Only medial and lateral perforations of the pedicle were documented (without neurological signs), cranial or caudal ones did not occur. Segmentation of the C-arm navigation into two comparable treatment periods showed a learning curve with a reduction of perforations in the second sequence (after 57 pedicle instrumentations) of about 15%, this was found to be not statistically significant. The fluoroscopic navigation of pedicle screws is a safe procedure at the lumbar spine with equal accuracy compared to the non-navigated conventional instrumentation. Application of C-arm navigation at the thoracic spine showed more inaccuracies, so that 3-D-based navigation seems to be advantageous in this region.

[Establishing a protein signature from prostate tissue biopsies]

The prostate-specific antigen test (PSA) has been a major factor contributing to a better management of prostate cancer. The low specificity limits its use in diagnosis especially in early detection of prostate cancer. Multiply expressed proteins need to be identified to establish a disease-specific protein signature that distinguishes between cancerous and noncancerous tissue. The first aim of our study is to identify differentially expressed proteins in both tissues using two-dimensional gel electrophoresis and subsequent mass spectrometry. We elucidated whether prostate biopsies are useful. First results have shown a different protein expression pattern in cancerous and noncancerous tissue. PCR revealed an increasing amount of mRNA for some upregulated proteins. We conclude that biopsies are useful material to establish protein expression patterns.

Expression of annexin AI in conventional renal cell carcinoma (CRCC) correlates with tumour stage, Fuhrman grade, amount of eosinophilic cells and clinical outcome

There is increasing evidence that Annexin AI (ANX AI) expression is dysregulated in several carcinomas and tumour cell lines. In order to gain insight into the putative role of ANX AI in tumorigenesis, clinical outcome and metastatic potential of conventional renal cell carcinomas (CRCCs) we investigated the expression of ANX AI in CRCCs and metastases. Furthermore, it was elucidated whether ANX AI overexpression affects migratory potential in Caki-1 cells. ANX AI immunohistochemistry was performed on 33 samples of CRCCs and 10 metastases. ANX AI expression was assessed in 12 samples by 2-dimensional gelelectrophoresis (2-DE), subsequent mass spectrometry and RT-PCR. Immunohistochemical data were statistically correlated with pathological parameters, amount of eosinophilic cells and clinical outcome. Furthermore, a haptotactic migration assay was done on Caki-1 cells transfected with ANX AI. Immunostaining for ANX AI was found in 18 tumours and all metastases investigated. Intensity of immunohistochemical staining correlated to Fuhrman grade, amount of eosinophilic cells and clinical outcome. 2-DE and RT-PCR confirmed the presence of ANX AI in neoplastic tissue. Overexpression of ANX AI did not significantly influence cell migration. From these findings ANX AI expression seems to be related to Fuhrman grade, clinical outcome and metastatic potential of CRCCs. Thus ANX AI could serve as a prognostic marker for tumour progression.

[Precision of navigation-assisted surgery of the thoracic and lumbar spine]

The goal of these studies was to evaluate the accuracy of in vivo and in vitro application of CT- and C-arm-based navigation at the thoracic and lumbar spine. With CT based navigation, 82 pedicle screws were consecutively inserted, 53 into the thoracic and 29 into the lumbar spine. Seven (13%) perforations were detected at the thoracic spine and two (7%) at the lumbar spine. Additionally, minor perforations below the thread depth were seen in six (11%) thoracic and in two (7%) lumbar instrumentation. With C-arm-based navigation, 74 screws were consecutively placed into 38 thoracic and 36 lumbar pedicles. Perforations were noted in ten (26%) thoracic and four (11%) lumbar implants. Minor perforations were observed in another nine (24%) thoracic and ten (28%) lumbar pedicles. The observer-independent and standardized in vitro study based on a transpedicular 3.2-mm drill hole aiming a 4-mm steel ball in a plastic bone model showed pedicle perforations of the drill canal only in thoracic vertebrae, 1 of 15 in CT-based and 3 of 15 in C-arm navigation. The quantitative calculation of the smallest distance between the central line through the drill canal and the center of the steel ball resulted in 1.4 mm (0.5-4.8 mm) for the CT-based navigation at the thoracic spine and in 1.8 mm (0.5-3 mm) at the lumbar spine. For the C-arm based navigation the distance was 2.6 mm (0.9-4.8 mm) for the thoracic spine and 2 mm (1.2-3 mm) for the lumbar spine. In our opinion, the clinical results of the comparative accuracy of CT- and C-arm-based navigation in the present study showed moderate advantages of the CT-based technique in the thoracic spine, whereas CT- and C-arm based navigation had comparable perforation rates at the lumbar pedicle. The results of the experimental study correlated with the clinical data.

Increased expression and altered location of annexin IV in renal clear cell carcinoma: a possible role in tumour dissemination

The proteome of renal cell carcinoma and non-neoplastic kidney tissue was analysed from 12 patients by two-dimensional polyacrylamide gel electrophoresis to search for differentially expressed proteins in the tumour. Annexin IV was identified to be up-regulated in tumour cells. These patients and further 11 were characterized by RT-PCR. We found an increased amount of annexin IV mRNA. Immunohistochemical analysis revealed an altered localization of annexin IV in tumour cells. Additionally we demonstrate that over-expressed annexin IV promotes cell migration in a carcinoma model system. From these results above it seems possible that annexin IV plays an important role in the morphological diversification and dissemination of the clear cell renal cell carcinoma.

Are NADP-dependent isocitrate dehydrogenases and ferredoxin-dependent glutamate synthase co-regulated by the same photoreceptors?

Activities of NADP-dependent isocitrate dehydrogenases (cytosolic and plastidic isoforms, ICDH1 and ICDH2; EC 1.1.1.42) and ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) in turions of Spirodela polyrhiza were all stimulated by light. Single or repeated red light (R) pulses induced the activity of the enzymes and this effect was reverted by subsequent far-red light (FR) pulses. The enzymes are, therefore, co-regulated by the low-fluence response of phytochrome. For ICDH, this is reported here for the first time. Neither an effect of the very low-fluence response nor of the FR-mediated high-irradiance response was detectable. Irradiance with continuous R resulted in enhanced enzyme activities and protein levels (Western analysis using polyclonal antibodies against ICDH1 and Fd-GOGAT). These additional effects of continuous R (called a "non-induction effect") could be inhibited for ICDH1 and ICDH2 by the inhibitor of photosynthetic electron transport, 3-(3',4'-dichlorophenyl)-1,1-dimethylurea, and are therefore related to the effect of photosynthesis. In contrast, the non-induction effect of Fd-GOGAT was resistant against this inhibitor. Moreover, hourly R pulses did not replace the effect of continuous R. The non-induction effect of light on the activity and protein level of Fd-GOGAT was therefore tentatively classified as an R-mediated high-irradiance response. The activity of Fd-GOGAT but not that of ICDHs was additionally regulated by a specific blue-light receptor. It can be concluded that the levels of ICDHs and Fd-GOGAT were coordinated by light but were not co-regulated by the same photoreceptors. Nitrate is necessary for the light regulation of both enzymes, contributing to the coordinated expression of the relevant genes.

Bis(1H-2-indolyl)-1-methanones as inhibitors of the hematopoietic tyrosine kinase Flt3

Aberrant expression and activating mutations of the class III receptor tyrosine kinase Flt3 (Flk-2, STK-1) have been linked to poor prognosis in acute myeloid leukemia (AML). Inhibitors of Flt3 tyrosine kinase activity are, therefore, of interest as potential therapeutic compounds. We previously described bis(1H-2-indolyl)-1-methanones as a novel class of selective inhibitors for platelet-derived growth factor receptors (PDGFR). Several bis(1H-2-indolyl)-1-methanone derivatives, represented by the compounds D-64406 and D-65476, are also potent inhibitors of Flt3. They inhibit proliferation of TEL-Flt3-transfected BA/F3 cells with IC(50) values of 0.2-0.3 microM in the absence of IL-3 but >10 microM in the presence of IL-3. Ligand-stimulated autophosphorylation of Flt3 in EOL-1 cells and corresponding downstream activation of Akt/PKB are effectively inhibited by bis(1H-2-indolyl)-1-methanones whereas autophosphorylation of c-Kit/SCF receptor or c-Fms/CSF-1 receptor is less sensitive or insensitive, respectively. Flt3 kinase purified by different methods is potently inhibited in vitro, demonstrating a direct mechanism of inhibition. 32D cells, expressing a constitutively active Flt3 variant with internal tandem duplication are greatly sensitized to radiation-induced apoptosis in the presence of D-64406 or D-65476 in the absence but not in the presence of IL-3. Thus, bis(1H-2-indolyl)-1-methanones are potential candidates for the treatment of Flt3-driven leukemias.

Bis(1H-2-indolyl)methanones as a novel class of inhibitors of the platelet-derived growth factor receptor kinase

The novel lead bis(1H-2-indolyl)methanone inhibits autophosphorylation of platelet-derived growth factor (PDGF) receptor tyrosine kinase in intact cells. Various substituents in the 5- or 6-position of one indole ring increase or preserve potency, whereas most modifications of the ring structures and of the methanone group as well as substitution at both indoles result in weak or no activity. An ATP binding site model, derived by homology from the FGFR-1 tyrosine kinase crystal structure suggesting hydrogen bonds of one indole NH and the methanone oxygen with the backbone carbonyl and amide, respectively, of Cys684, explains why only one indole moiety is open for substitution and locates groups in the 5- or 6-position outside the pocket. The hitherto most active derivatives, 39, 53 and 67, inhibit both isoforms of the PDGF receptor kinase in intact cells, with IC(50) of 0.1-0.3 microM, and purified PDGFbeta-receptor in vitro, with IC(50) of 0.09, 0.1, or 0.02 microM, respectively. PDGF-stimulated DNA synthesis is inhibited by these derivatives with IC(50) values of 1-3 microM. Kinetic analysis of 53 showed an ATP-competitive mode of inhibition. The compounds are inactive or weakly active toward a number of other tyrosine kinases, including the FGF receptor 1, EGF receptor, and c-Src kinase, as well as toward serine-threonine kinases, including different PKC isoforms and GRK2, and appear therefore selective for PDGF receptor inhibition.

Pyrrolo[3,4-c]-beta-carboline-diones as a novel class of inhibitors of the platelet-derived growth factor receptor kinase

Members of the structurally diverse family of beta-carbolines have previously been shown to exhibit a wide range of biological activities. A novel synthetic strategy for generation of beta-carbolines was developed, allowing imido-beta-carbolines to be created in three steps from known compounds. The compounds were screened for inhibition of platelet-derived growth factor (PDGF)-stimulated tyrosine phosphorylation in Swiss 3T3 fibroblasts. A number of the newly synthesized beta-carbolines with moderate to potent inhibitory activity were revealed. The most active derivative, 2,3-dihydro-8,9-dimethoxy-5-(2-methylphenyl)-1H,6H-pyrrolo[3, 4-c]pyrido¿3,4-bĭndole-1,3-dione 2ee, inhibited purified PDGF receptor kinase and PDGF-receptor autophosphorylation in intact cells with IC(50) values of 0.4 and 2.6 microM, respectively. Dione 2ee also inhibited PDGF-stimulated DNA synthesis in Swiss 3T3 fibroblasts with an IC(50) of 3.2 microM. The compound had no effect on Src or epidermal growth factor (EGF) receptor kinase activity and a six-seven-fold higher IC(50) for inhibition of basic fibroblast growth factor (bFGF)-stimulated tyrosine phosphorylation or Kit/stem cell factor (SCF) receptor autophosphorylation, indicating a reasonable extent of kinase specificity. Thus, beta-carbolines present a new lead of tyrosine kinase inhibitors with the capacity to selectively interfere with PDGF receptor signal transduction and PDGF-dependent cell growth.

Purification and characterization of a fully active recombinant tobacco cytosolic NADP-dependent isocitrate dehydrogenase in Escherichia coli: evidence for a role for the N-terminal region in enzyme activity

The recently isolated full-length NADP-dependent isocitrate dehydrogenase (ICDH) cDNA encoding the tobacco cytosolic isoenzyme has been cloned into the expression vector pET8c and used to transform Escherichia coli strain BL21 (DE3). The recombinant protein was purified to electrophoretic homogeneity and used to raise polyclonal antibodies. Its kinetic properties were found to be identical to those of the cytosolic ICDH isoenzyme purified from tobacco cell cultures. The recombinant and the endogenous bacterial ICDH could be easily distinguished by their different behaviors during anion-exchange column chromatography and immunological response. An incomplete ICDH-encoding cDNA clone, encoding a protein lacking the first 36 amino acids at the N-terminus, was cloned into the expression vector pKK233-2 and used to transform ICDH-lacking E. coli cells (strain 2004). The truncated, recombinant ICDH produced by the bacteria was found to be inactive.

Dose-dependent and time-dependent pharmacokinetics in the dog after intravenous administration of dextrorphan

The disposition of dextrorphan after single ascending iv doses and multiple iv dosing regimens was studied in Marshall beagle dogs. A dose-dependent decrease in plasma clearance was observed after the administration of single iv doses of 0.88 mg/kg, 2.64 mg/kg, and 8.8 mg/kg of dextrorphan (i.e. mean plasma clearance values +/- SD were 100 +/- 25 vs. 68 +/- 28 vs. 48 +/- 20 ml/min.kg, respectively; p less than 0.001). Upon multiple dosing, the plasma clearance of dextrorphan increased in a time-dependent fashion for the two highest doses, approaching values observed for the 0.88 mg/kg/day iv dosing regimen. Female dogs exhibited a greater increase in plasma clearance with time. For all dogs, however, dextrorphan plasma clearance approached or exceeded hepatic plasma flow rate, suggesting the possibility of extrahepatic metabolism or elimination. Modest dose- and time-dependent changes in the steady-state volume of distribution of dextrorphan also were observed. The AUC of the conjugated metabolites of dextrorphan decreased in a time-dependent manner for the 8.8 mg/kg/day dosing regimen. The nonlinear kinetics of dextrorphan after iv administration appeared to occur only after potentially toxic dosing regimens of dextrorphan hydrochloride. We postulate mechanisms to explain the dose- and time-dependent kinetics of dextrorphan observed in the beagle dog.