Establishment of a novel specific ELISA system for rat N- and C-ERC/mesothelin. Rat ERC/mesothelin in the body fluids of mice bearing mesothelioma

CD109 expression in tumor cells and stroma correlates with progression and prognosis in pancreatic cancer

CD109 is a glycosylphosphatidylinositol-anchored glycoprotein, whose expression is upregulated in some types of malignant tumors. High levels of CD109 in tumor cells have been reported to correlate with poor prognosis; however, significance of CD109 stromal expression in human malignancy has not been elucidated. In this study, we investigated the tumorigenic properties of CD109 in pancreatic ductal adenocarcinoma (PDAC). Immunohistochemical analysis of 92 PDAC surgical specimens revealed that positive CD109 expression in tumor cells was significantly associated with poor prognosis (disease-free survival, p = 0.003; overall survival, p = 0.002), and was an independent prognostic factor (disease-free survival, p = 0.0173; overall survival, p = 0.0104) in PDAC. Furthermore, CD109 expression was detected in the stroma surrounding tumor cells, similar to that of α-smooth muscle actin, a histological marker of cancer-associated fibroblasts. The stromal CD109 expression significantly correlated with tumor progression in PDAC (TNM stage, p = 0.033; N factor, p = 0.024; lymphatic invasion, p = 0.028). In addition, combined assessment of CD109 in tumor cells and stroma could identify the better prognosis group of patients from the entire patient population. In MIA PaCa-2 PDAC cell line, we demonstrated the involvement of CD109 in tumor cell motility, but not in PANC-1. Taken together, CD109 not only in the tumor cells but also in the stroma is involved in the progression and prognosis of PDAC, and may serve as a useful prognostic marker in PDAC.

A New CD10 Antibody Inhibits the Growth of Malignant Mesothelioma

Malignant mesotheliomas (MMs) are aggressive therapy-resistant tumors that generally have a poor prognosis. We previously reported the establishment of four new monoclonal antibodies (mAbs) for the diagnosis and treatment of MM. In this report, we characterized one of these antibodies, JMAM-1. The molecules whose antibodies were calibrated were picked up, transfected assuming CD10, and elucidated by fluorescence activated cell sorter. Survival experiments were performed using tumor-bearing mice model. JMAM-1 mAb was found to bind with CD10 antigen. The Kaplan–Meier survival curve showed a small but prolonged survival effect. JMAM-1 mAb-treated MSTO-211H cells showed increased cell cycle arrest involved by cyclin-dependent-kinase. JMAM-1 antibody has cytostatic effect and may be a candidate for the treatment of MM. Among mesothelioma, CD10-positive cases have been reported to have a poorer prognosis than negative cases, which can be used as a tool for diagnosis.

CD109 mediates tumorigenicity and cancer aggressiveness via regulation of EGFR and STAT3 signalling in cervical squamous cell carcinoma

Background

CD109 was involved in the tumorigenesis and progression of various cancers via TGF-β1 signalling and STAT3 activation. As CD109 is strongly expressed in cervical squamous cell carcinoma, this study was conducted to investigate its functional characteristics in cervical cancer.

Methods

CD109 expression was examined by immunohistochemistry (IHC) with cervical tissue microarray. The effects of CD109 expression were examined on migration, cell proliferation, spheroid formation and soft-agar colony-formation assay. Meanwhile, cervical cancer cell lines with high CD109 expression were chosen for the functional study using siRNA knockdown and CRISPR/Cas9 knockout.

Results

IHC demonstrated an upregulation of CD109 in the cell membrane of cervical squamous cell carcinoma. CD109( + ) cells isolated by flow-cytometric sorting displayed enhanced migration, cell proliferation, sphere-forming and anchorage-independent cell growth ability. In contrast, silencing of CD109 expression could reverse the in vitro and in vivo tumorigenic and aggressive properties. Furthermore, CD109 induced EGFR-mediated STAT3 phosphorylation known to be responsible for cell migration, proliferation and maintenance of CSC phenotype.

Conclusion

Abundant CD109( + ) populations in cervical cancer cells potentially contributed to carcinogenesis and aggressiveness, whereas silencing of CD109 expression could reverse those properties. CD109 mediates cervical tumorigenicity and aggressiveness via CD109/EGFR/STAT3 signalling.

CD109 and squamous cell carcinoma

Squamous cell carcinoma (SCC) is well-known for its high rate of metastasis with poor prognosis. CD109 is a glycosylphosphatidylinositol-anchored cell-surface glycoprotein. Recently, CD109 emerges as a potential biomarker and a therapeutic target for SCCs. Accumulating studies have reported that CD109 is highly expressed in human SCCs of multiple organs, and may contribute to the progression of SCCs. In this review, we summarized the findings on expression pattern of CD109 in SCCs, and discussed the molecular mechanisms underlying the roles of CD109 in pathogenesis of SCCs.

Development of improved therapeutic mesothelin-based vaccines for pancreatic cancer

Pancreatic cancer is the 5^th leading cause of cancer deaths, and there are no effective treatments. We developed a poxvirus platform vaccine with improved immunogenicity and inserted the mesothelin gene to create an anti-mesothelin cancer vaccine. Mesothelin expression is mostly restricted to tumors in adult mammals and thus may be a good target for cancer treatment. We show here that the modified vaccinia virus Ankara (MVA) virus expressing mesothelin and the enhanced MVA virus missing the immunosuppressive A35 gene and expressing mesothelin were both safe in mice and were able to induce IFN-gamma secreting T cells in response to mesothelin expressing tumor cells. In addition, the MVA virus has oncolytic properties in vitro as it can replicate in and kill Panc02 pancreatic adenocarcinoma cell line tumor cells, even though it is unable to replicate in most mammalian cells. Deletion of the A35 gene in MVA improved T cell responses as expected. However, we were unable to demonstrate inhibition of Panc02 tumor growth in immunocompetent mice with pre-vaccination of mice, boosts, or even intratumoral injections of the recombinant viruses. Vaccine efficacy may be limited by shedding of mesothelin from tumor cells thus creating a protective screen from the immune system.

Myxofibrosarcoma primary cultures: molecular and pharmacological profile

Background:

Myxofibrosarcoma (MFS), formerly considered as a myxoid variant of malignant fibrous histiocytoma, is the most common sarcoma of the extremities in adults and is characterized by a high frequency of local recurrence. The clinical behavior of MFS is unpredictable and the efficacy of chemotherapy is still not well documented. Furthermore, given the relatively recent recognition of MFS as a distinct pathologic entity its cellular and molecular biology has still not been extensively studied in patient-derived preclinical models. We examined the molecular biology and treatment outcomes of high-grade, patient-derived MFS primary cultures.

Methods:

A total of three patient-derived MFS primary cultures were analyzed. We evaluated the role of CD109 expression and also looked for a correlation between transforming growth factor-beta (TGF-β) expression and sensitivity of the primary cultures to different drugs.

Results:

CD109 was a promising marker for the identification of more aggressive high-grade MFS and a potential therapeutic target. The results also highlighted the potential role of TGF-β in chemoresistance. Pharmacological analysis confirmed the sensitivity of the cultures to chemotherapy. The most active treatments were epirubicin alone and epirubicin in combination with ifosfamide, the latter representing the current standard of care for soft tissue sarcomas (STSs), including MFS.

Conclusions:

Our results provide a starting point for further research aimed at improving the management of MFS patients undergoing chemotherapy.

CD109, a negative regulator of TGF-β signaling, is a putative risk marker in diffuse large B-cell lymphoma

CD109 is a glycosylphosphatidylinositol-anchored glycoprotein that negatively regulates TGF-β signaling. CD109 was originally identified in hematopoietic tumors; however, the significance of CD109 in hematopoietic malignancies remains unclear. Here, we study the association of CD109 with diffuse large B-cell lymphoma (DLBCL) prognosis. Eighty-four DLBCL specimens were immunohistochemically analyzed for CD109 expression, and 31 and 53 cases were classified into low- and high-CD109 expression groups, respectively. CD109 expression was not associated with overall survival using the Kaplan-Meier analysis and log-rank tests (P = 0.17); however, a significant association was observed between high-CD109 expression and low-1-year survival (P = 0.01). Moreover, in combination with the revised International Prognostic Index (R-IPI), R-IPI-poor/CD109-high was associated with poorer prognosis compared with R-IPI-poor alone. We assessed TGF-β signaling in CD109-depleted Nalm6 cells (a human B-lymphoblastic leukemia/lymphoma cell line), and found prolonged Smad2 phosphorylation compared with control cells after TGF-β1 stimulation, suggesting that CD109 attenuates TGF-β1 signaling in human B-cell tumors. These results suggest that CD109 is a putative biomarker for identifying a high-risk group among DLBCL patients.

Murine mesothelin: characterization, expression, and inhibition of tumor growth in a murine model of pancreatic cancer

Background

Mesothelin has attracted much interest as a tumor specific antigen; it has been reported to promote tumor development and to be a good target for cancer treatment. Most studies to date have used human mesothelin in immunocompromised mice. Since these models do not allow for study of the natural immune response to mesothelin expressing tumors, we have undertaken the characterization of mouse mesothelin so the effects of this protein can be assessed in immunocompetent mouse strains.

Methods

We analyzed mouse mesothelin expression, tissue distribution, shedding and biochemistry. In addition we constructed stable mesothelin overexpressing lines of the pancreatic cancer line Panc02 by two methods and tested them for growth and tumorigencity in vitro and in vivo.

Results

We show here that mouse mesothelin is similar to human mesothelin in biochemical characteristics, tumor expression and tissue distribution, suggesting the mouse may be a suitable model for study of mesothelin. Stable overexpression of mesothelin in a pancreatic cancer cell line did not increase cell proliferation or anchorage-independent growth in vitro, suggesting that mesothelin is not necessarily a tumor progression factor. Surprisingly overexpression of mesothelin inhibited tumor formation in vivo in immunocompetent mice.

Conclusion

The mouse may be a good model for studying mesothelin in the context of an intact immune response. Mesothelin is not necessarily a tumor progression factor, and indeed mesothelin overexpression inhibited tumor growth in immunocompetent mice.

Soluble CD109 binds TGF-β and antagonizes TGF-β signalling and responses

Transforming growth factor-β (TGF-β) is a multifunctional cytokine implicated in many diseases, including tissue fibrosis and cancer. TGF-β mediates diverse biological responses by signalling through type I and II TGF-β receptors (TβRI and TβRII). We have previously identified CD109, a glycosylphosphatidylinositol (GPI)-anchored protein, as a novel TGF-β co-receptor that negatively regulates TGF-β signalling and responses and demonstrated that membrane-anchored CD109 promotes TGF-β receptor degradation via a SMAD7/Smurf2-mediated mechanism. To determine whether CD109 released from the cell surface (soluble CD109 or sCD109) also acts as a TGF-β antagonist, we determined the efficacy of recombinant sCD109 to interact with TGF-β and inhibit TGF-β signalling and responses. Our results demonstrate that sCD109 binds TGF-β with high affinity as determined by surface plasmon resonance (SPR) and cell-based radioligand binding and affinity labelling competition assays. SPR detected slow dissociation kinetics between sCD109 and TGF-β at low concentrations, indicating a stable and effective interaction. In addition, sCD109 antagonizes TGF-β-induced Smad2/3 phosphorylation, transcription and cell migration. Together, our results suggest that sCD109 can bind TGF-β, inhibit TGF-β binding to its receptors and decrease TGF-β signalling and TGF-β-induced cellular responses.

Membrane proteome analysis of glioblastoma cell invasion

Glioblastoma multiforme (GBM) tumor invasion is facilitated by cell migration and degradation of the extracellular matrix. Invadopodia are actin-rich structures that protrude from the plasma membrane in direct contact with the extracellular matrix and are proposed to participate in epithelial-mesenchymal transition. We characterized the invasiveness of 9 established GBM cell lines using an invadopodia assay and performed quantitative mass spectrometry-based proteomic analyses on enriched membrane fractions. All GBM cells produced invadopodia, with a 65% difference between the most invasive cell line (U87MG) and the least invasive cell line (LN229) (p = 0.0001). Overall, 1,141 proteins were identified in the GBM membrane proteome; the levels of 49 proteins correlated with cell invasiveness. Ingenuity Pathway Analysis predicted activation "cell movement" (z-score = 2.608, p = 3.94E(-04)) in more invasive cells and generated a network of invasion-associated proteins with direct links to key regulators of invadopodia formation. Gene expression data relating to the invasion-associated proteins ITGA5 (integrin α5), CD97, and ANXA1 (annexin A1) showed prognostic significance in independent GBM cohorts. Fluorescence microscopy demonstrated ITGA5, CD97, and ANXA1 localization in invadopodia assays, and small interfering RNA knockdown of ITGA5 reduced invadopodia formation in U87MG cells. Thus, invasion-associated proteins, including ITGA5, may prove to be useful anti-invasive targets; volociximab, a therapeutic antibody against integrin α5β1, may be useful for treatment of patients with GBM.

Genome-wide association study of copy number variations (CNVs) with opioid dependence

Single-nucleotide polymorphisms that have been associated with opioid dependence (OD) altogether account for only a small proportion of the known heritability. Most of the genetic risk factors are unknown. Some of the 'missing heritability' might be explained by copy number variations (CNVs) in the human genome. We used Illumina HumanOmni1 arrays to genotype 5152 African-American and European-American OD cases and screened controls and implemented combined CNV calling methods. After quality control measures were applied, a genome-wide association study (GWAS) of CNVs with OD was performed. For common CNVs, two deletions and one duplication were significantly associated with OD genome-wide (eg, P=2 × 10(-8) and OR (95% CI)=0.64 (0.54-0.74) for a chromosome 18q12.3 deletion). Several rare or unique CNVs showed suggestive or marginal significance with large effect sizes. This study is the first GWAS of OD using CNVs. Some identified CNVs harbor genes newly identified here to be of biological importance in addiction, whereas others affect genes previously known to contribute to substance dependence risk. Our findings augment our specific knowledge of the importance of genomic variation in addictive disorders, and provide an addiction CNV pool for further research. These findings require replication.

Rat N-ERC/mesothelin as a marker for in vivo screening of drugs against pancreas cancer

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease, which is usually diagnosed in an advanced stage. We have established transgenic rats carrying a mutated K-ras gene controlled by Cre/loxP activation. The animals develop PDA which is histopathologically similar to that in humans. Previously, we reported that serum levels of N-ERC/mesothelin were significantly higher in rats bearing PDA than in controls. In the present study, to determine whether serum levels of N-ERC/mesothelin correlated with tumor size, we measured N-ERC/mesothelin levels in rats bearing PDA. Increased serum levels of N-ERC/mesothelin correlated with increased tumor size. This result indicates an interrelationship between the serum level of N-ERC/mesothelin and tumor size. We next investigated the effect of chemotherapy on serum N-ERC/mesothelin levels. Rat pancreatic cancer cells were implanted subcutaneously into the flank of NOD-SCID mice. In the mice treated with 200 mg/kg gemcitabine, tumor weight and the serum level of N-ERC/mesothelin were significantly decreased compared to controls. These results suggest that serum N-ERC/mesothelin measurements might be useful for monitoring response to therapy.

Iron overload signature in chrysotile-induced malignant mesothelioma

Exposure to asbestos is a risk for malignant mesothelioma (MM) in humans. Among the commercially used types of asbestos (chrysotile, crocidolite, and amosite), the carcinogenicity of chrysotile is not fully appreciated. Here, we show that all three asbestos types similarly induced MM in the rat peritoneal cavity and that chrysotile caused the earliest mesothelioma development with a high fraction of sarcomatoid histology. The pathogenesis of chrysotile-induced mesothelial carcinogenesis was closely associated with iron overload: repeated administration of an iron chelator, nitrilotriacetic acid, which promotes the Fenton reaction, significantly reduced the period required for carcinogenesis; massive iron deposition was found in the peritoneal organs with high serum ferritin; and homozygous deletion of the CDKN2A/2B/ARF tumour suppressor genes, the most frequent genomic alteration in human MM and in iron-induced rodent carcinogenesis, was observed in 92.6% of the cases studied with array-based comparative genomic hybridization. The induced rat MM cells revealed high expression of mesoderm-specific transcription factors, Dlx5 and Hand1, and showed an iron regulatory profile of active iron uptake and utilization. These data indicate that chrysotile is a strong carcinogen when exposed to mesothelia, acting through the induction of local iron overload. Therefore, an intervention to remove local excess iron might be a strategy to prevent MM after asbestos exposure.

CD105 (Endoglin) exerts prognostic effects via its role in the microvascular niche of paediatric high grade glioma

Paediatric high grade glioma (pHGG) (World Health Organisation astrocytoma grades III and IV) remains poor prognosis tumours, with a median survival of only 15 months following diagnosis. Current investigation of anti-angiogenic strategies has focused on adult glioblastoma multiforme (GBM) with phase III trials targeting vascular endothelial growth factor continuing. In this study we investigated whether the degree of vascularity correlated with prognosis in a large cohort of pHGG (n = 150) and whether different vessel markers carried different prognostic value. We found that CD105 (endoglin) had a strongly significant association with poor prognosis on multivariate analysis (p = <0.001). Supervised hierarchical clustering of genome wide gene expression data identified 13 genes associated with differential degrees of vascularity in the cohort. The novel angiogenesis-associated genes identified in this analysis (including MIPOL-1 and ENPP5) were validated by realtime polymerase chain reaction. We also demonstrate that CD105 positive blood vessels associate with CD133 positive tumour cells and that a proportion of CD105 positive vessel cells demonstrates co-positivity for CD133, suggesting that the recently described phenomenon of vasculogenic mimicry occurs in pHGG. Together, the data suggest that targeting angiogenesis, and in particular CD105, is a valid therapeutic strategy for pHGG.

LRRN4 and UPK3B are markers of primary mesothelial cells

BACKGROUND

Mesothelioma is a highly malignant tumor that is primarily caused by occupational or environmental exposure to asbestos fibers. Despite worldwide restrictions on asbestos usage, further cases are expected as diagnosis is typically 20-40 years after exposure. Once diagnosed there is a very poor prognosis with a median survival rate of 9 months. Considering this the development of early pre clinical diagnostic markers may help improve clinical outcomes.

METHODOLOGY

Microarray expression arrays on mesothelium and other tissues dissected from mice were used to identify candidate mesothelial lineage markers. Candidates were further tested by qRTPCR and in-situ hybridization across a mouse tissue panel. Two candidate biomarkers with the potential for secretion, uroplakin 3B (UPK3B), and leucine rich repeat neuronal 4 (LRRN4) and one commercialized mesothelioma marker, mesothelin (MSLN) were then chosen for validation across a panel of normal human primary cells, 16 established mesothelioma cell lines, 10 lung cancer lines, and a further set of 8 unrelated cancer cell lines.

CONCLUSIONS

Within the primary cell panel, LRRN4 was only detected in primary mesothelial cells, but MSLN and UPK3B were also detected in other cell types. MSLN was detected in bronchial epithelial cells and alveolar epithelial cells and UPK3B was detected in retinal pigment epithelial cells and urothelial cells. Testing the cell line panel, MSLN was detected in 15 of the 16 mesothelioma cells lines, whereas LRRN4 was only detected in 8 and UPK3B in 6. Interestingly MSLN levels appear to be upregulated in the mesothelioma lines compared to the primary mesothelial cells, while LRRN4 and UPK3B, are either lost or down-regulated. Despite the higher fraction of mesothelioma lines positive for MSLN, it was also detected at high levels in 2 lung cancer lines and 3 other unrelated cancer lines derived from papillotubular adenocarcinoma, signet ring carcinoma and transitional cell carcinoma.

CD109 release from the cell surface in human keratinocytes regulates TGF-β receptor expression, TGF-β signalling and STAT3 activation: relevance to psoriasis

Transforming growth factor (TGF)-β is an important cytokine that negatively regulates keratinocyte proliferation. Deregulation of TGF-β signalling has been reported in psoriasis, where despite increased expression of TGF-β, psoriatic keratinocytes continue to hyperproliferate. Recently, we have identified CD109, a glycosyl phosphatidylinositol (GPI)-anchored protein, as a novel co-receptor and negative regulator of TGF-β signalling. In the current work, we demonstrate that release of CD109 from the cell surface or the addition of CD109 protein results in downregulation of TGF-β signalling and TGF-β receptor expression in human keratinocytes. Moreover, these effects are associated with an increase in phospho-STAT3 levels, enhanced total STAT3 and Bcl-2 expression and an increase in cell growth and survival, suggesting that released/soluble CD109 is able to induce molecular changes that are known to occur in psoriasis. Analysis of CD109 expression in psoriasis patients reveals that CD109 protein expression is markedly decreased in psoriatic epidermis as compared to adjacent uninvolved skin. In contrast, CD109 mRNA expression is unchanged in psoriatic plaques in comparison with normal skin. This raises a possibility that CD109 protein release is enhanced in psoriatic keratinocytes. Furthermore, psoriatic epidermis displays decreased expression of TGF-β receptors, consistent with the results obtained in vitro in keratinocytes with CD109 release or addition of CD109 recombinant protein. Together our findings suggest that aberrant CD109 release from the cell surface in human keratinocytes may induce molecular changes that are usually observed in psoriasis and may explain TGF-β receptor downregulation and decrease in TGF-β signalling in psoriasis.

Serum level of expressed in renal carcinoma (ERC)/ mesothelin in rats with mesothelial proliferative lesions induced by multi-wall carbon nanotube (MWCNT)

Expressed in renal carcinoma (ERC)/mesothelin is a good biomarker for human mesothelioma and has been investigated for its mechanistic rationale during the mesothelioma development. Studies are thus ongoing in our laboratories to assess expression of ERC/mesothelin in sera and normal/proliferative/neoplastic mesothelial tissues of animals untreated or given potentially mesothelioma-inducible xenobiotics, by an enzyme-linked immunosorbent assay (ELISA) for N- and C-(terminal fragments of) ERC/mesothelin and immunohistochemistry for C-ERC/mesothelin. In the present paper, we intend to communicate our preliminary data, because this is the first report to show how and from what stage the ERC/mesothelin expression changes during the chemical induction of mesothelial proliferative/neoplatic lesions. Serum N-ERC/mesothelin levels were 51.4 +/- 5.6 ng/ml in control male Fischer 344 rats, increased to 83.6 +/- 11.2 ng/ml in rats given a single intrascrotal administration of 1 mg/kg body weight of multi-wall carbon nanotube (MWCNT) and bearing mesothelial hyperplasia 52 weeks thereafter, and further elevated to 180 +/- 77 ng/ml in rats similarly treated and becoming moribund 40 weeks thereafter, or killed as scheduled at the end of week 52, bearing mesothelioma. While C-ERC/mesothelin was expressed in normal and hyperplastic mesothelia, the protein was detected only in epithelioid mesothelioma cells at the most superficial layer. It is thus suggested that ERC/mesothelin can be used as a biomarker of mesothelial proliferative lesions also in animals, and that the increase of levels may start from the early stage and be enhanced by the progression of the mesothelioma development.

Processing of CD109 by furin and its role in the regulation of TGF-beta signaling

CD109 is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein, whose expression is upregulated in squamous cell carcinomas of the lung, esophagus, uterus and oral cavity. CD109 negatively regulates transforming growth factor (TGF)-beta signaling in keratinocytes by directly modulating receptor activity. In this study, we further characterized CD109 regulation of TGF-beta signaling and cell proliferation. We found that CD109 is produced as a 205 kDa glycoprotein, which is then processed in the Golgi apparatus into 180 kDa and 25 kDa proteins by furin (furinase). 180 kDa CD109 associated with GPI-anchored 25 kDa CD109 on the cell surface and was also secreted into the culture medium. To investigate whether furinase cleavage of CD109 is necessary for its biological activity, we mutated arginine 1273 in the CD109 furinase cleavage motif (amino acid 1270-RRRR-1273) to serine (R1273S). Interestingly, CD109 R1273S neither significantly impaired TGF-beta signaling nor affected TGF-beta-mediated suppression of cell growth, although it was expressed on the cell surface as a 205 kDa protein. Consistent with this finding, the 180 kDa and 25 kDa CD109 complex, but not CD109 R1273S, associated with the type I TGF-beta receptor. These findings indicate that processing of CD109 into 180 kDa and 25 kDa proteins by furin, followed by complex formation with the type I TGF-beta receptor is required for the regulation of TGF-beta signaling in cancer cells and keratinocytes.

An animal model of preclinical diagnosis of pancreatic ductal adenocarcinomas

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease, which is usually diagnosed in an advanced stage. Animal PDA models which reflect the human condition are clearly necessary to develop early diagnostic tools and explore new therapeutic approaches. We have established transgenic rats carrying a mutated H- or K-ras gene (Hras250 and Kras327) controlled by Cre/loxP activation. These animals develop PDA which are histopathologically similar to that in humans. We utilized this model to identify biomarkers to detect early PDA. We report here that serum levels of Erc/Mesothelin are significantly higher in rats bearing PDA than in controls. Importantly, the levels are significantly elevated in rats before grossly visible carcinomas develop. Even in rats with very small microscopic ductal carcinoma lesions, elevated serum Erc/Mesothelin can be detected. We believe this is the first report of a pancreas tumor animal model in which pre-symptomatic lesions can be diagnosed.