Anti-CA19-9 Antibody [121SLE] (A86801)

Neurogenin 3 (NGN3) is necessary and sufficient for endocrine differentiation during pancreatic development and is expressed by a population of progenitor cells that give rise exclusively to hormone-secreting cells within islets. NGN3 protein can be detected in the adult rodent pancreas only following certain types of injury, when it is transiently expressed by exocrine cells undergoing reprogramming to an endocrine cell fate. Here, NGN3 protein can be detected in 2% of acinar and duct cells in living biopsies of histologically normal adult human pancreata and 10% in cadaveric biopsies of organ donor pancreata. The percentage and total number of NGN3+ cells increase during culture without evidence of proliferation or selective cell death. Isolation of highly purified and viable NGN3+ cell populations can be achieved based on coexpression of the cell surface glycoprotein CD133. Transcriptome and targeted expression analyses of isolated CD133+ / NGN3+ cells indicate that they are distinct from surrounding exocrine tissue with respect to expression phenotype and Notch signaling activity, but retain high level mRNA expression of genes indicative of acinar and duct cell function. NGN3+ cells have an mRNA expression profile that resembles that of mouse early endocrine progenitor cells. During in vitro differentiation, NGN3+ cells express genes in a pattern characteristic of endocrine development and result in cells that resemble beta cells on the basis of coexpression of insulin C-peptide, chromogranin A and pancreatic and duodenal homeobox 1. NGN3 expression in the adult human exocrine pancreas marks a dedifferentiating cell population with the capacity to take on an endocrine cell fate. These cells represent a potential source for the treatment of diabetes either through ex vivo manipulation, or in vivo by targeting mechanisms controlling their population size and endocrine cell fate commitment.

Circulating leukocytes that express selectin ligands such as the carbohydrate epitope sialyl Lewis X (sLeX) may interact with endothelial selectins, resulting in transmigration of the leukocyte across the endothelial wall to adjacent tissue. Due to the potential of selectin-ligand interactions as targets in viral pathogenesis, we aimed at determining whether herpes simplex virus type 1 (HSV1) is able to induce the appearance of sLeX at the surface of infected leukocytes. We found that HSV1 infection of a T-cell line resulted in transcriptional activation of human fucosyltransferase genes FUT3, FUT6 and FUT7, the two latter genes encoding the fucosyltransferases rate limiting for sLeX synthesis. Flow cytometry and confocal microscopy demonstrated that HSV1 infection resulted in a 2-fold rise in the proportion of sLeX-positive cells. Increased levels of FUT3, FUT6 and FUT7 RNA were detected already at 3 h post infection, and treatment with cycloheximide, a translation inhibitor, blocked a HSV1-induced increase in the expression of FUT3, FUT6 and FUT7 RNA, suggesting involvement of viral or cellular proteins. Studies with infectious viral mutants indicated that the viral immediate early (α) protein ICP0 is essential for the initiation of FUT7 though not for FUT3 or FUT6 transcription. In CD3+ cells, derived from peripheral blood mononuclear cells, HSV1 infection induced expression of FUT3, FUT5 and FUT6, whereas FUT7 was not altered. The mean sLeX fluorescence intensity of CD3+ cells was significantly higher in HSV1-infected CD3+ cells. This suggests that infected leukocytes during HSV1 viremia may express selectin ligands with possible but as yet unproven roles in viral pathogenesis.

The CA 19-9 antigen is currently the best individual marker for the detection of pancreatic cancer. In order to optimize the CA 19-9 assay and to develop approaches to further improve cancer detection, it is important to understand the specificity differences between CA 19-9 antibodies and the consequential affect on biomarker performance. Antibody arrays enabled multiplexed comparisons between five different CA 19-9 antibodies used in the analysis of plasma samples from pancreatic cancer patients and controls. Major differences were observed between antibodies in their detection of particular patient samples. Glycan array analysis revealed that certain antibodies were highly specific for the canonical CA 19-9 epitope, sialyl-Lewis A, while others bound sialyl-Lewis A in addition to a related structure called sialyl-Lewis C and modification with Nue5Gc. In a much larger patient cohort, we confirmed the binding of sialyl-Lewis C glycan by one of the antibodies and showed that the broader specificity led to the detection of an increased number of cancer patients without increasing detection of pancreatitis patient samples. This work demonstrates that variation between antibody specificity for cancer-associated glycans can have significant implications for biomarker performance and highlights the value of characterizing and detecting the range of glycan structures that are elevated in cancer.

Mouse models of human cancers may provide a valuable resource for the discovery of cancer biomarkers. We have developed a practical strategy for profiling specific proteins in mouse plasma using low-volume sandwich-immunoassays. We used this method to profile the levels of 14 different cytokines, acute-phase reactants, and other cancer markers in plasma from a mouse models of intestinal tumors and their wild-type littermates, using as little as 1.5 microliters of diluted plasma per assay. Many of the proteins were significantly and consistently up-regulated in the mutant mice. The mutant mice could be distinguished nearly perfectly from the wild-type mice based on the combined levels of as few as three markers. Many of the proteins were up-regulated even in the mutant mice with few or no tumors, suggesting the presence of a systemic host response at an early stage of cancer development. These results have implications for the study of host responses in mouse models of cancers and demonstrate the value of a new low-volume, high-throughput sandwich-immunoassay method for sensitively profiling protein levels in cancer.

The ISOBM TD-6 Workshop is the first international workshop on monoclonal antibodies against the Sialyl Lewisa (SLea) antigen. Eight research groups participated in a blind study to characterize the epitope binding, relative affinity and performance in immunoradiometric assays, of a panel of 20 monoclonal antibodies. The antibodies were tested against a diverse panel of neoglycoconjugates, purified antigens and human serum pools from gastrointestinal malignancies. Epitope specificities were determined for the majority of antibodies in the panel. Cross-reactivity with related saccharide structures was noted in several antibodies. Overall, the results of the TD-6 Workshop show further development of SLea immunoassays may yield yet more specific assays for the detection and management of gastrointestinal and other malignancies.

BACKGROUND AND OBJECTIVE:

E- and P-selectins expressed on the luminal surface of mesodermally derived endothelial cells play a crucial role in the formation of haematogenous metastases in a number of malignancies. As peritoneal mesothelial cells are also derived form the mesoderm, it was hypothesised that selectins are also of importance in peritoneal tumour spread.

METHODS:

Immunohistochemistry was used to identify selectin expression on normal human peritoneum and isolated mesothelial cells. E- and P-selectin interactions with human pancreatic adenocarcinoma cells were investigated in dynamic flow assays and flow cytometry; the latter was also used to determine the main selectin ligands on pancreatic adenocarcinoma cell lines PaCa 5061, BxPC-3 and PaCa 5072, and selectin expression on human mesothelial cells. All cell lines were xenografted into the peritoneum of E- and P-selectin-deficient pfp/rag2 mice and selectin wild-type controls. Peritoneal carcinomatosis was quantified using MRI or a scoring system.

RESULTS:

E- and P-selectin were constitutively expressed on human mesothelial and endothelial cells in the peritoneum. PaCa 5061 and BxPC-3 cells interacted with E- and P-selectins in dynamic flow assays and flow cytometry, with CA19-9 (Sialyl Lewis a) being the main E-selectin ligand. For xenografted PaCa 5061 and BxPC-3 cells, peritoneal metastasis was significantly reduced in E- and P-selectin double knockout mice compared with wild-type pfp/rag2 animals. In contrast, PaCa 5072 cells were almost devoid of selectin binding sites and no intraperitoneal tumour growth was observed.

CONCLUSION:

Interactions of tumour cells with peritoneal selectins play an important role in the peritoneal spread of pancreatic adenocarcinoma.

BACKGROUND:

Glycosylation of the tumour cell surface is of importance in metastasis formation as indicated by lectin-binding studies. In particular, binding of the lectin HPA is associated with metastasis formation, both in clinical studies and in xenograft models of breast and colon cancer. Here we examined if there is an association between the HPA-positive glycotopes of metastasizing cancer cells and selectin-binding properties.

MATERIALS AND METHODS:

Glycotope expression of human breast and colon cancer cells (MCF7, T47D, HBL100, HT29, SW480) grown in culture and xenografted into SCID mice were investigated by histochemical analysis.

RESULTS:

HPA binding was observed in metastasizing breast and colon cancers and not in non-metastasizing ones. In colon cancer, E-selectin binding and expression of the selectin ligands CD15s and CA19-9 was higher in metastatic HT29 than in non-metastatic SW480 cells, especially when cells were grown in vitro. In breast cancer, E-selectin binding, CD15s and CA19-9 expression were independent of the metastatic potential. P-Selectin binding was slightly higher in metastasizing breast cancer cells (MCF7, T47D) than in non-metastasizing HBL100 cells.

CONCLUSION:

Binding to E-selectin and expression of E-selectin ligands of colon cancer cells grown in vitro is associated with metastasis formation in a xenograft model. However, analysis of selectin ligands is of limited predictive value for the metastatic potential of breast cancer cells in our xenograft model.