Expression of cripto in Human Pancreatic Tumors

The expression of cripto gene product was examined immunohistochemically in 45 surgically resected pancreatic tumors, including 32 invasive ductal carcinomas, 4 intraductal papillary adenocarcinomas, 4 intraductal papillary adenomas, 2 mucinous cystadenomas, 2 islet cell tumors, and one solid and cystic tumor, and compared with that in 32 areas of accompanying chronic pancreatitis present in the cases of invasive ductal carcinomas and 5 non-tumorous areas of pancreas without pancreatitis. All pancreatic ductal tumors including adenomas and carcinomas showed positive staining with no difference in terms of staining intensity among intraductal tumors and invasive carcinomas with or without mucin hypersecretion. Islet cell tumors were positively stained but the solid and cystic tumor was negative. Duct epithelial cells and acinar cells were negative but islet cells were positive in the pancreas tissues without pancreatitis. Cells arranged in duct-like structures in areas of accompanying chronic pancreatitis were positively stained. The results suggest that cripto expression might be associated with a growth advantage of tumor cells and also with differentiation to form duct-like structures.     

A Case of Mistaken Identity? Nonductal Origins of Pancreatic “Ductal” Cancers

In this issue of Cancer Cell, Guerra and colleagues provide important new insights regarding the ability of specific pancreatic cell types to generate invasive pancreatic cancer. First, they demonstrate that classical pancreatic "ductal" neoplasia can be induced by activation of oncogenic Kras in nonductal exocrine cells. Second, they show that, while Kras activation in immature acinar and centroacinar cells is readily able to induce ductal neoplasia, Kras-mediated tumorigenesis in mature exocrine pancreas requires the induction of chronic epithelial injury. The results shed new light on the "cell of origin" of pancreatic ductal cancer and demonstrate that chronic pancreatitis provides a permissive environment for Kras-induced pancreatic neoplasia.     

Expression of human regenerating gene mRNA and its product in normal and neoplastic human pancreas.

BACKGROUND. Localization of human regenerating gene (reg) mRNA and its product was investigated in normal and neoplastic human pancreas with the in situ hybridization method and immunohistochemical studies. METHODS. Both reg mRNA and reg protein were observed in acinar cells of the pancreas, but neither was found in ductal or islet cells. Immunoreactive reg was observed in an acinar cell carcinoma, a pancreatoblastoma, a solid and cystic tumor, and 5 of 20 duct cell carcinomas, but it was not found in 15 endocrine tumors and 2 microcystic adenomas. RESULTS. For comparison with reg, alpha-1-antitrypsin (AAT), lysozyme, chromogranin A (CMG), CA 19-9, carcinoembryonic antigen (CEA), cytokeratin, vimentin, and alpha-fetoprotein (AFP) were assessed in those tumors. An acinar cell carcinoma and a pancreatoblastoma had positive results for AAT, lysozyme, cytokeratin, and AFP but negative results for vimentin. An acinar cell carcinoma showed cells focally immunoreactive for CMG and CEA. A solid and cystic tumor had strongly positive results for AAT and vimentin and focally positive results for CMG and pancreatic hormones. Microcystic adenomas had abundant glycogen and strong immunoreactivity for cytokeratin. Ductal cell carcinomas showed cells focally positive for AAT, lysozyme, CMG, CA 19-9, and CEA. CONCLUSIONS. The localization of reg protein was not consist with that of any other proteins examined in the current study. Thus, reg protein was considered a useful marker for acinar cell differentiation; however, ectopic expression of reg also was observed in ductal cell carcinomas. In ductal cell carcinomas, expression of reg immunoreactivity was considered as one of phenotypic heterogeneity, as seen in AAT, lysozyme, and CMG immunoreactivity.     

Animal models of exocrine pancreatic carcinogenesis

In order to understand the evolution, histogenesis, and biological behaviour of exocrine pancreatic carcinoma, some reproducible experimental models have been developed in certain rodent species. To date, more than 16 chemicals, many of them structurally unrelated, have been shown to induce pancreatic tumors. Although some of these chemicals appear species specific in their effect on the pancreas, others have been shown to be capable of inducing pancreatic tumors in more than one species. In hamsters, the administration of diisopropylnitrosamine or its oxidized metabolites leads to the development of ductal adenocarcinomas that histologically resemble human pancreatic carcinomas. The histogenesis of the ductal type of adenocarcinoma in hamsters is complex, and appears to involve both the duct cells and dedifferentiated acinar cells. All pancreatic tumors in rats develop from acinar cells showing variable degrees of differentiation, regardless of the type of carcinogen used. The type of pancreatic lesions that develop in mice are also of acinar cell origin. In guinea pigs the tumors are adenocarcinomas of the ductal type and are shown to be derived from dedifferentiated acinar cells that have undergone duct-like transformation. Irrespective of the type of tumor that develops in these experimental animals, all of these models can be successfully used to evaluate the various modifying (risk) factors and biological behaviour of these neoplasms.     

Expression Profile and Potential Roles of EVA1A in Normal and Neoplastic Pancreatic Tissues

Background: EVA1A (eva-1 homolog A) is a novel gene that regulates programmed cell death throughautophagy and apoptosis. Our objective was to investigate the expression profiles and potential role of EVA1Ain normal and neoplastic human pancreatic tissues. Materials and Methods: The expression pattern of EVA1Ain normal pancreatic tissue was examined by indirect immunofluorescence and confocal microscopy. Proteinlevels in paraffin-embedded specimens from normal and diseased pancreatic and matched non-tumor tissueswere evaluated by immunohistochemistry. Results: EVA1A colocalized with glucagon but not with insulin,demonstrating production in islet alpha cells. Itwas strongly expressed in chronic pancreatitis, moderately orweakly expressed in the plasma membrane and cytoplasm in pancreatic acinar cell carcinoma, and absent innormal pancreatic acinar cells. Although the tissue architecture was deformed, EVA1A was absent in the alphacells of pancreatic ductal adenocarcinomas, intraductal papillary mucinous neoplasms, mucinous cystadenomas,solid papillary tumors and pancreatic neuroendocrine tumors. Conclusions: EVA1A protein is specificallyexpressed in islet alpha cells, suggesting it may play an important role in regulating alpha-cell function. Theectopic expression of EVA1A in pancreatic neoplasms may contribute to their pathogenesis and warrants furtherinvestigation.     

Pancreatic carcinoma with duct, endocrine, and acinar differentiation. A histologic, immunocytochemical, and ultrastructural study

An unusual case of pancreatic carcinoma with components of poorly differentiated adenocarcinoma and islet cell tumor is reported. Histologic, immunocytochemical, and ultrastructural evidence of ductal, endocrine, and exocrine (acinar) differentiation is presented. The implications with regard to endocrine cell differentiation and the histogenesis of pancreatic neoplasms are discussed.     

ErbB2 oncogene antibodies differentiate between the normal and diseased pancreas, and between chronic pancreatitis and pancreatic cancer

Histological differentiation between chronic pancreatitis and pancreatic cancer, especially in biopsy material, remains challenging and the frequent association of 'secondary' chronic pancreatitis (due to ductal obstruction) with pancreatic cancer causes additional diagnostic problems. Our study, using anti-ErbB2 antibodies from Santa Cruz and Dako in tissues from the normal pancreas, chronic pancreatitis and pancreatic cancer showed that these antibodies discriminate between primary chronic pancreatitis and 'secondary' chronic pancreatitis due to pancreatic cancer. Tissues from 28 pancreatic cancer patients, 15 chronic pancreatitis patients and 12 organ donors or early autopsy cases were subjected to immunohistochemical studies using polyclonal ErbB2 antibodies from Santa Cruz and Dako. The Santa Cruz antibody immunoreacted with islet cells in all tissues from the normal pancreas and pancreatic cancer but not in any chronic pancreatitis specimen. The Dako antibody showed a membrane staining of ductal and ductular cells only in chronic pancreatitis cases but in none of the normal or cancer specimens. Moreover, in chronic pancreatitis cases, ductular cells were stained with the Santa Cruz antibody only in the severe form, but not in the mild or moderate form of the disease. The utilized ErbB2 antibodies discriminate between the normal pancreas, chronic pancreatitis and pancreatic cancer. Hence, these antibodies seem to present an additional useful aid in the surgical pathology of pancreatic diseases.     

Developmental aspects of early pancreatic cancer

The specific cell of origin responsible for generating pancreatic intraepithelial neoplasia and pancreatic ductal adenocarcinoma remains unknown. During development, epithelial stem cells within embryonic pancreatic epithelium give riseto mature acinar, ductal, and islet elements. Emerging evidence suggests that cells with precursor potential also exist within adult pancreas, resulting in significant developmental plasticity among both endocrine and exocrine cell types. In this review, the contribution of developmental plasticity in initiating pancreatic metaplasia and neoplasia is considered, and evidence supporting a role for epithelial stem cells in pancreatic cancer is discussed.     

Human pancreatic ribonuclease 1: expression and distribution in pancreatic adenocarcinoma

BACKGROUND: Human pancreatic ribonuclease (RNase 1) is a pancreatic enzyme that is present at high levels in the serum of most patients with pancreatic adenocarcinoma. For this reason, the authors studied its patterns of expression at the single-cell level in pancreatic adenocarcinoma tissues by immunohistochemical analysis and in situ hybridization (ISH). METHODS: Immunohistochemical analysis with polyclonal antibodies against RNase 1 and by ISH with digoxigenin-labeled RNase 1 probe were used to detect RNase 1 in the neoplastic cells of ductal type pancreatic adenocarcinomas. RESULTS: Fifteen of 18 carcinoma samples were positive for RNase 1, demonstrating that the expression of ribonuclease that the authors observed previously in human pancreatic adenocarcinoma cell lines was not an artifact of cell culture. The authors also found RNase 1 in some of the metaplastic ducts and atrophic islets in 4 of 6 chronic pancreatitis samples, and they observed RNase 1 immunostaining in hyperplastic ducts adjacent to one of the well-differentiated adenocarcinomas. CONCLUSIONS: The expression levels of RNase 1 by tumor cells from pancreatic adenocarcinomas are consistent with the high RNase 1 levels found in the serum of most patients with pancreatic adenocarcinoma. This expression of RNase 1, which is an acinar protein, demonstrates that the patterns of gene expression in pancreatic adenocarcinoma are distinct from those of normal pancreatic duct cells. Conversely, RNase 1 expression levels in altered ductal cells from some chronic pancreatitis tissues and hyperplastic ducts from carcinoma tissues suggest that abnormal expression levels may be an early event in pancreatic tumorigenesis.     

Immunocytochemical markers of uncommon pancreatic tumors. Acinar cell carcinoma, pancreatoblastoma, and solid cystic (papillary-cystic) tumor

Nine acinar cell carcinomas of the pancreas, 2 pancreatoblastomas, 16 solid-cystic (papillary-cystic) tumors, and 20 ductal adenocarcinomas were immunocytochemically investigated using antisera against four pancreatic enzymes (alpha-amylase, lipase, trypsinogen, chymotrypsinogen), four pancreatic hormones, neuron specific enolase (NSE), alpha-1-antitrypsin (AAT), carcinoembryonic antigen (CEA), and CA 19-9. Lipase, trypsinogen, and chymotrypsinogen, but no alpha-amylase were detected in all acinar cell carcinomas and pancreatoblastomas. In contrast, solid-cystic tumors (SCT) were negative for pancreatic enzymes but 2 of 16 stained with NSE. No neuroendocrine granules or pancreatic hormones could be demonstrated. AAT was found in all tumors except ductal adenocarcinomas, which stained with CEA and CA 19-9. The study established pancreatic enzymes (except alpha-amylase) as immunocytochemical markers for acinar cell carcinomas and pancreatoblastomas. There is as yet no marker specific for SCT, which would elucidate the obscure histogenetic origin and phenotypic differentiation of these tumors.     

ADAM9 expression in pancreatic cancer is associated with tumour type and is a prognostic factor in ductal adenocarcinoma

Gene expression profiling revealed ADAM9 to be distinctly overexpressed in pancreatic ductal adenocarcinoma (PDAC). We examined the relevance of ADAM9 expression in PDAC diagnosis and prognosis. A total of 59 infiltrating PDACs, 32 specimens from patients with chronic pancreatitis, 11 endocrine tumours and 24 acinar cell carcinomas were immunohistochemically analysed for ADAM9 expression. Staining for ADAM9 was detected in 58 out of 59 (98.3%) PDACs and in two out of 24 (8.3%) acinar cell carcinomas, but not in endocrine tumours. In the non-neoplastic pancreas, whether normal or chronically inflamed, ADAM9 was expressed in centroacinar and intralobular duct cells, but not in interlobular duct cells and their hyperplastic lesions. Pancreatic ductal adenocarcinomas showing cytoplasmic ADAM9 expression correlated with poor tumour differentiation and also with shorter overall survival than in cases showing only an apical membranous staining pattern (P=0.001). Multivariate analysis identified cytoplasmic ADAM9 expression as an independent marker of shortened survival in a set of 42 curatively (R0) resected PDAC (P<0.05, hazard ratio 2.85, 95% confidence interval: 1.21-6.71). The results show that ADAM9 expression distinguishes PDACs from other solid pancreatic tumours. In addition, cytoplasmic ADAM9 overexpression is associated with poor differentiation and shortened survival. Therefore, ADAM9 overexpression might contribute to the aggressiveness of PDACs.     

Syndecan-1 expression is up-regulated in pancreatic but not in other gastrointestinal cancers

Syndecan-1 belongs to the syndecan family of cell surface transmembrane heparan-sulfate proteoglycans, which participate in cell proliferation, cell migration and cell-matrix interactions. Decreased expression of syndecan-1 has been observed in some gastrointestinal malignancies, and it is thought that high levels of syndecan-1 correlate with the maintenance of epithelial morphology and inhibition of invasiveness. In our study, we characterized the expression of syndecan-1 in normal, chronic pancreatitis and primary and metastatic human pancreatic cancer tissues, in cultured pancreatic cancer cell lines and in esophageal, gastric, colon, and liver cancers. Pancreatic cancer cell lines expressed syndecan-1 mRNA and protein at variable levels. In addition, these cells also released syndecan-1 into the culture medium. Pancreatic cancer tissues markedly over-expressed syndecan-1 mRNA in comparison with both chronic pancreatitis (2.4-fold increase, p < 0.01) and normal pancreatic samples (10.6-fold increase, p < 0.01). There was no difference in syndecan-1 mRNA expression between early and advanced tumors. By in situ hybridization and immunohistochemistry, syndecan-1 expression was evident at relatively low levels in the ductal cells and less frequently in acinar cells of the normal pancreas. In chronic pancreatitis, syndecan-1 was present at low to moderate levels in areas with atrophic acinar cells and ductular complexes. In contrast, in pancreatic cancer tissues, syndecan-1 was present at moderate to high levels in the majority of the cancer cells within the tumor mass and also in metastatic lesions of pancreatic tumors. Syndecan-1 mRNA levels in other gastrointestinal malignancies (esophageal, gastric, colon and liver cancers) were not significantly different from the levels observed in the corresponding normal samples. Together, our findings suggest that syndecan-1 expression by pancreatic cancer cells may be of importance in the pathobiology of this disorder and that its role in pancreatic cancer seems to be different from that in other gastrointestinal malignancies.     

Fas (CD95/APO-1) and Fas ligand expression in normal pancreas and pancreatic tumors. Implications for immune privilege and immune escape

BACKGROUND: Fas (CD95/APO-1) and Fas ligand (FasL) play key roles in immunologic homeostasis and immune privilege and may regulate normal cell turnover. Earlier studies had suggested that FasL-positive pancreatic carcinoma cell lines can induce apoptosis in T cells, thereby evading host immune surveillance. In the current study the authors have characterized the expression of Fas and FasL in the normal pancreas and in pancreatic neoplasia. METHODS: Pancreatic resection specimens with ductal-type adenocarcinoma or intraductal dysplasia (n = 41), nonductal pancreatic neoplasms (n = 5), and chronic pancreatitis (n = 4) were examined for Fas and FasL expression by immunohistochemistry. The results in invasive adenocarcinoma were compared to those for benign ducts and intraductal dysplasia, and correlated with clinicopathologic features of the tumors and with patient survival. RESULTS: Fas was expressed in the normal pancreatic ducts and in intraductal dysplasia in a mixed membrane/cytoplasmic pattern. In all cases of invasive ductal-type adenocarcinoma, membranous Fas could not be detected; cytoplasmic Fas staining was reduced or completely lost. Loss of Fas expression in pancreatic ductal-type adenocarcinomas significantly correlated with poorer differentiation and extrapancreatic spread of the tumors and was associated with a shorter overall survival. FasL expression was present in the normal pancreatic ducts as well as in islet cells and was maintained in all pancreatic tumors. CONCLUSIONS: These results implicate the Fas pathway in the regulation of physiologic cell turnover and immune privilege in the normal pancreas and indicate that loss of Fas expression is correlated with malignant transformation and biologic aggressiveness in pancreatic adenocarcinomas. This may represent a mechanism by which pancreatic tumor cells become resistant to apoptosis and escape immune surveillance in vivo.     

Overexpression of ErbB2 in the exocrine pancreas induces an inflammatory response but not increased proliferation

Tyrosine kinase receptors such as members of the epidermal growth factor receptor family and their respective ligands are frequently overexpressed in pancreatic cancer as well as in chronic pancreatitis. In this study, the role of ErbB2 in the exocrine pancreas was examined by ectopic overexpression under the control of the proximal rat elastase promoter. Three independent transgenic mouse lines overexpressing ErbB2 were established by pronuclear injection. Pancreatic mRNA and protein levels were analyzed by real time PCR, immunohistochemistry and immunoblot analysis, RAS activity by using a specific immunoprecipitation assay and various kinase activities by phosphospecific antibodies. Overexpression of ErbB2 in the exocrine pancreas resulted in increased RAS activity and downstream activation of ERK1/2, but not in transgenic increased proliferation of acinar and ductal cells. At later timepoints, some mice showed focal areas of acinar cell damage with upregulated mRNA levels for Cyclin D1 and p16(INK4a). Despite the increased mRNA level, cyclin D1 protein levels were downregulated. We observed areas of focal infiltrations with inflammatory cells interspersed in the exocrine pancreas. NF-kappaB activity was induced in transgenic acinar cells compared with controls contributing to high levels of chemokine and cytokine gene expression such as CCR-1 and CCL3. These data suggest that overexpression of ErbB2 in acinar cells leads to increased RAS activity without cell cycle progression and mediates inflammation via NF-kappaB. We conclude that the biological response of ErbB2/RAS signaling depends highly on cellular context.     

Cripto,a member of the epidermal growth factor family,is over-expressed in human pancreatic cancer and chronic pancreatitis

Cripto is a 188 amino-acid protein containing a central segment that shares amino-acid sequence homology with epidermal growth factor (EGF) and transforming growth factor alpha (TGF-α). The EGF receptor, EGF and TGF-α are expressed in the normal human pancreas, and are over-expressed in human pancreatic cancer. Therefore, in the present study we sought to determine whether cripto is found in the normal human pancreas and whether its expression is altered in pancreatic cancer. Because chronic pancreatitis (CP) is associated with interstitial fibrosis similar to that observed in pancreatic cancer, we also examined cripto expression in pancreatic tissues from patients with CP. In the normal pancreas, cripto immunoreactivity was found at moderate levels in most ductal cells and was present very faintly in a rare acinar cell. In 26 of 58 pancreatic cancers, cripto immunoreactivity was present in many cancer cells. Its presence was associated with advanced tumor stage, but not with shorter post-operative survival. Cripto was also present in acinar and ductal cells adjacent to the cancer cells, and in many ductal and atrophic acinar cells in the CP samples. Northern blot analysis revealed a marked increase in cripto mRNA levels in the cancer and CP samples. By densitometry, there was a 11 - and 4-fold increase in cripto mRNA levels in pancreatic cancer and CP respectively. Southern blot analysis did not reveal an increase in gene copies encoding cripto either in cancer or in CP. These findings indicate that cripto expression may contribute to disease progression in pancreatic cancer, and implicate cripto in the histopathological alterations that occur in the pancreas both in cancer and in CP.     

Ductal metaplasia of human exocrine pancreas and its association with carcinoma

Monoclonal antibodies to cell surface markers of human exocrine pancreas were used to establish the cytotypic expression of cells forming "tubular complexes" in pancreases from six adults without carcinoma and in the nontumorous pancreatic parenchyma of 16 pancreases with carcinoma. These cells manifested duct cell determinants. In general, the presence of cells with duct cell surface markers within the acini corresponded to the normal distribution of centroacinar cells in the 30 control human pancreases (from cadaveric donors); however, foci of abnormal acini were seen in these pancreases independent of or intermingled with the "tubular complexes." The acini in these abnormal areas were formed by a core of cells and cell processes that expressed duct cell determinants. They were partially surrounded by acinar cells and showed slight or no lumenal dilation. While the causative agent(s), the cell(s) of origin, and the regression and/or progression of these lesions are yet to be determined, the replacement of acini by the spectrum of lesions composed of cells with duct cell surface marker is suggested to constitute ductal metaplasia.     

Ductal origin of pancreatic adenocarcinomas induced by conditional activation of a human Ha-ras oncogene in rat pancreas

Pancreatic ductal adenocarcinoma is one of the most debilitating malignancies in humans. Currently, radiation and chemotherapy are ineffective, with median survival times after treatment of <12 months. Animal models that reflect the human condition and can be used to explore screening and therapeutic approaches are clearly desirable. One feature of human pancreatic adenocarcinoma is an exceedingly high frequency of K-ras mutation. The present study was conducted to determine if targeted activation of a human oncogenic-ras transgene in rat pancreas would induce carcinomas correspondent to human pancreatic ductal adenocarcinomas. We established transgenic (Hras250) rats in which expression of a human Ha-rasG12V oncogene is regulated by the Cre/lox system. Targeted pancreatic activation of the transgene was accomplished by injection of Cre-carrying adenovirus into the pancreatic ducts and acini through the common bile duct. Adenoviral infection of injected animals was exclusive to the pancreas; infected cells could be identified in duct, intercalated duct, centroacinar and, less frequently, acinar cells, but not in endocrine islet cells. Four weeks after injection, proliferative lesions in the duct epithelium, intercalated ducts and centroacinar cells, but not acinar cells, were widespread. Tumorigenesis in other tissues was not observed. Most lesions, including atypical duct proliferative lesions, PanIN-like lesions and carcinomas, were positive for cytokeratins 19 and 7, cyclooxygenase 2 and MMP-7 but negative for amylase and chymotrypsin. Many adenocarcinoma lesions were positive for EGF and EGFR. Duct epithelial and atypical duct proliferative lesions and carcinoma lesions were all positive for transduced Ha-rasG12V oncogene expression. The cytogenesis of pancreatic ductal type carcinoma was depicted. This model exhibits important similarities to the human disease and promises to advance our understanding of the behavior of pancreas adenocarcinomas and expedite screening and therapy.     

Enhanced expression of annexin II in human pancreatic carcinoma cells and primary pancreatic cancers

Annexin II is a calcium and phospholipid binding protein anda substrate for protein-tyrosine kinases. Recent investigationshave revealed involvement of annexin II in DNA synthesis andcell proliferation. Increased levels of annexin II are observedin cancer cells and tissues. To investigate the expression ofannexin II in pancreatic adenocarcinoma cells and primary tumors,we measured the levels of annexin II mRNA and protein in normalhuman pancreas, five established human pancreatic adenocarcinomacell lines, three primary pancreatic cancers and one metastatictumor. All five cell lines examined had 5- to 15-fold higherlevels of annexin II as compared to normal pancreas. Significantelevations (2-to 8-fold) of annexin II expression were observedin the three primary pancreatic tumors and one metastatic tumorexamined. Immunocytochemical analysis indicates that the increasedexpression of annexin II is limited to proliferating ductularadenocarcinoma, and annexin II expression co-localizes withcells that express PCNA. In normal pancreas, annexin II expressionis seen in ductal and ductular cells and no expression is seenin acinar or islet cells. We conclude from these findings thatannexin II has a role in cell proliferation and its regulationis altered in pancreatic cancer.     

Pten constrains centroacinar cell expansion and malignant transformation in the pancreas

To determine the role of the phosphatidylinositol 3-kinase (PI3-K) pathway in pancreas development, we generated a pancreas-specific knockout of Pten, a negative regulator of PI3-K signaling. Knockout mice display progressive replacement of the acinar pancreas with highly proliferative ductal structures that contain abundant mucins and express Pdx1 and Hes1, two markers of pancreatic progenitor cells. Moreover, a fraction of these mice develop ductal malignancy. We provide evidence that ductal metaplasia results from the expansion of centroacinar cells rather than transdifferentiation of acinar cells. These results indicate that Pten actively maintains the balance between different cell types in the adult pancreas and that misregulation of the PI3-K pathway in centroacinar cells may contribute to the initiation of pancreatic carcinoma in vivo.     

Production of three monoclonal antibodies specifically reactive respectively with the ductal, acinar and islet cells of the human pancreas.

Three monoclonal antibodies, designated FP-1, FP-2 and FP-3, were obtained by immunizing a BALB/c mouse with dispersed human fetal pancreatic cells and using hybridoma technology. FP-1, FP-2 and FP-3 reacted specifically, respectively, with the ductal epithelial, acinar and islet cells, of the fetal pancreas as well as with adult human pancreatic tissue, suggesting a use in the discrimination of pancreatic cell types. Upon screening various tumor tissues, FP-1 was found to react with adenocarcinomas of the pancreas (16/23), stomach (7/8), colon (4/6) and gall bladder (2/2) as well as with the three malignant cell lines, PANC-1 (pancreas), HT-29 (colon) and LoVo (colon). In contrast to FP-1, FP-2 and FP-3 reacted with only 5% (2/39) and 0% (0/39), respectively, of these adenocarcinomas. Although FP-3 did not react with any of these adenocarcinomas, it did react with various APUDoma cells such as islet cell tumors of the pancreas (3/5), pheochromocytomas (2/2), medullary thyroid carcinomas (2/3) and gastrointestinal carcinoids (1/3). FP-3 thus appears to be the first monoclonal antibody with extremely high endocrine cell specificity.