Anti-CD24 Antibody [SN3] (FITC) (A86015)

Evidence suggests that multiple tumors, including pancreatic adenocarcinoma, display heterogeneity in parameters that are critical for tumor formation, progression and metastasis. Understanding heterogeneity in solid tumors is increasingly providing a plethora of new diagnostic and therapeutic approaches. In this study, a particular focus was put on identifying a subpopulation of stem cell-like, slow cycling tumor cells in a pancreas adenocarcinoma cell lines. Using a label retention technique a subpopulation of slow cycling cells (DiI+/SCC) was identified and further evaluated in the BxPC-3 and Panc03.27 cell lines. These slowly cycling cells managed to retain the lipophilic labeling dye DiI, while the bulk of the cells (>94%) did not. The DiI+/SCC population, showed only a partial overlap with the CSC markers CD24(+)/CD44(+), CD133(+) and ALDH but they survived chemotherapeutic treatment, and were able to recreate the initial heterogeneous tumor cell population. DiI+/SCCs exhibited an increased invasive potential as compared with their non-label retaining, faster cycling cells (DiI-/FCC). They also had increased tumorigenic potential and morphological changes resembling cells that have undergone an epithelial to mesenchymal transition (EMT). Analysis of DiI+/SCC cells by real time PCR revealed a selective up-regulation of tell tale components of the Hedgehog/TGFbeta pathways, as well as a down-regulation of EGFR, combined with a shift in crucial components implied in EMT. The presented findings offer an expanded mechanistic understanding that associates tumor initiating potential with cycling speed and EMT in pancreatic cancer cell lines.

BACKGROUND:

The estrogen receptor-positive M13SV1 breast epithelial cell line was proposed to be a suitable in vitro model for breast cancer research since two derivatives with graduated tumorigenicity-M13SV1-R2-2 and M13SV1-R2-N1-are available for this cell line. In the present study, these three cell lines were comparatively examined for their morphological and their biochemical properties on the molecular level.

METHODS:

A transcriptomic approach (gene array analysis) was chosen to unravel differences in gene expression among the three cell lines. Network analysis was conducted to identify deregulated signaling pathways. Cellular viability was determined by impedance measurements as well as by neutral red uptake assay. Apoptosis was determined by using a caspase assay. For morphological characterization, cells were grown in three-dimensional cell culture, and cellular differentiation and spheroid formation was followed by immunofluorescence staining by using confocal laser scanning microscopy.

RESULTS:

The gene array results indicated that there were only marginal differences in gene expression among the three cell lines. Network analysis predicted the R2-N1 derivative (1) to display enhanced apoptosis and (2) to have a higher migration capability compared to its parent cell line M13SV1. Enhanced apoptosis was confirmed by elevated caspase activity, and increased migration was observed in 3D culture when cells migrated out of the globular spheroids. In 3D cell culture, all three cell lines similarly formed spheroids within three days, but there was no acini formation until day 21 which is indicated by a growth arrest around day 15, cellular polarization, and the formation of hollow lumen inside the spheroids. These characteristics, however, are crucial to study, e.g., the differentiation process of breast epithelial cells in vitro.

CONCLUSION:

Due to the molecular and morphological features, the M13SV1 cell line and its tumorigenic derivatives seem to be less suitable as in vitro models than other cell lines such as the MCF-10A cell line which displays proper acini formation in 3D culture.

Recurrence of breast cancer after chemotherapy is thought to arise from resistant breast cancer stem cells which are eventually able to repopulate the tumor. The Hedgehog (HH) signaling pathway has been shown to regulate the proliferation and survival of breast cancer stem cells, and has been shown to promote resistance to chemotherapy through the activation of multi-drug resistance and pro survival pathways. Here we report that exposure of heterogenous breast cancer cell lines to docetaxel (DOC) resulted in release of Sonic Hedgehog ligand (SHH) and activation of the HH pathway as evidenced by increased expression and nuclear translocation of the downstream effector Gli-1 at 4-24 h after DOC treatment. This activation had little effect on the bulk of the tumor cell population as inhibition of HH signaling failed to increase apoptosis in response to DOC. However, HH pathway activation was required for clonogenic growth of cell lines after DOC. Increases in stemness markers as well as mammosphere formation were observed after treatment with DOC suggesting an increase in the breast cancer stem cell populations. These increases were similar to that of cell lines cultured in the presence of recombinant SHH and could be eliminated by co-treatment with HH inhibitors. These results suggest that HH pathway activation induced by DOC treatment does not have a chemosensitizing effect on the heterogeneous tumor population, but may be required for survival and expansion of breast cancer stem cells after chemotherapy.

A monoclonal antibody, SN3, has been prepared against a cell membrane fraction of the pre-B leukemic cell line NALM-1. By radioimmunoassay, SN3 reacted with four of four non-T/non-B, two of two pre-B and one of three leukemic B cell lines. The reagent was unreactive, however, with established leukemic T and myelomonocytic cell lines or normal B cell lines. On immunohistochemical assays on frozen sections of nine reactive lymph nodes and three spleens, SN3 showed a preferential binding to 50-95 per cent mantle zone (MZ) cells and 5-20 per cent interfollicular or red pulp B-lymphocytes. This was uninhibited by pre-incubation with heterologous anti-HLA-DR or anti-delta reagents. SN3 was unreactive with normal germinal centre (GC), epidermal or Langerhans cells but did react with less than 1 per cent thymic B-lymphocytes. In eight follicular small cleaved cell lymphomas tested SN3 exhibited three patterns of reactivity: peripheral follicular, combined peripheral and central follicular, and combined follicular and interfollicular. Three follicular lymphomas were essentially SN3-. In three diffuse small lymphocytic lymphomas, SN3 showed patchy areas of reactivity unassociated with proliferation centres. In four diffuse B-cell lymphomas (one mixed small and large cell, two large non-cleaved cell, and one small non-cleaved (Burkitt) cell), SN3 reactivity was uniformly distributed in the majority (60-90 per cent) of the cells. SN3 was unreactive with one diffuse B-large cell lymphoma, three nodal T-cell lymphomas and three cases of mycosis fungoides. The findings indicate that SN3 detects an antigen that is present in subpopulations of normal MZ cells, the antigen is also detected in GC cells undergoing lymphomatous transformation but is not readily detected in normal GC cells, and the antigen is also expressed in subpopulations of diffuse B- but not T-cell lymphomas.

We have generated and characterized three new monoclonal antibodies (mAbs), termed SN3, SN3a, and SN3b, which are directed to sialic acid of a glycoprotein(s) on human non-T leukemia cells. These mAbs were generated by immunizing mice with an antigen preparation isolated from cell-membrane glycoconjugates of NALM-1, a pre-B leukemia cell line. The initial characterization of the mAbs consisted of a sensitive cellular radioimmunoassay against various cultured human leukemia-lymphoma (HLL) and nonmalignant cell lines. They strongly reacted with all four (all three in the case of SN3a) non-T/non-B HLL cell lines tested and both pre-B HLL cell lines tested. However, they reacted with only one of three B HLL cell lines tested. In addition, these mAbs did not react with other cell lines, which include T- and myelomonocytic HLL cell lines and nonmalignant B-cell lines. Normal peripheral blood cells were also tested; the mAbs reacted with B cells and granulocytes but not with T cells, monocytes, erythrocytes, or platelets. In a test using SN3 and SN3b with uncultured cell specimens derived from various cancer patients, the mAbs primarily reacted with non-T/non-B and B HLL specimens, as well as with chronic myelocytic leukemia specimens. The biochemical nature of antigenic determinants defined by the three mAbs was studied by treating the non-T leukemia cells with sialidase and proteases. The results show that the antigenic determinants defined by these mAbs all contain a sialic acid residue(s) that is attached to the cells via a protein backbone(s). Competitive binding experiments show that binding of SN3 to the leukemia cells was blocked almost completely by SN3a and SN3b, as well as by BA-1. Both SN3 and SN3a are IgG1 antibodies, whereas SN3b is an IgM antibody; SN3b showed a strong complement-mediated cytotoxic activity against non-T leukemia cells.

BACKGROUND & AIMS:

Pancreatic adenocarcinoma (PAC) is often diagnosed at an advanced and inoperable stage, and standard systemic treatments are generally ineffective. We investigated the effects of adoptive transfer of tumor-specific T cells that express chimeric antibody-based receptors (CAR) to mice with primary and metastatic PAC xenografts.

METHODS:

Human effector T cells were genetically modified to express CAR against Her2/neu or CD24, a putative PAC stem cell antigen. The antitumor reactivity of the engineered T cells (T-bodies) was evaluated in SCID mice with different PAC xenografts. A total of 1 × 10(7) T-bodies were injected via the tail vein or directly administered to the subcutaneous tumor on 3 or 4 alternating days. Mice were then given twice-daily intraperitoneal injections of interleukin-2 for 10 days.

RESULTS:

Intratumor injection of human CD24 and Her2/neu-specific T-bodies completely eliminated the tumors from most animals. Intravenous injection of T-bodies reduced tumor size and prolonged survival of mice with orthotopically transplanted tumors; more than 50% of animals appeared to be disease-free more than 2 months later. Additional systemic administration of T-bodies 8 weeks after the initial injection eliminated primary tumors, along with liver and draining lymph node metastases. A single administration of the Her2/neu-specific T-bodies prolonged the survival of mice with tumors in which most of the cells expressed the target antigen. In contrast, the CD24-specific T-bodies prolonged survival of mice in which only a subpopulation of the tumor cells expressed the antigen.

CONCLUSIONS:

CAR-redirected T cells stop growth and metastasis of PAC xenografts in mice. T-bodies specific to CD24, a putative cancer stem cell antigen, were effective against PAC xenografts that had only a subset of antigen-expressing cells.

Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.

PURPOSE:

Low-grade fibromyxoid sarcoma (LGFMS) is typically characterized by the specific translocation t(7;16)(q33;p11) and the corresponding fusion gene FUS-CREB3L2. The present study aimed to extract LGFMS-specific, and putatively FUS-CREB3L2-dependent, gene expression patterns to learn more about the pathogenesis of this tumor.

EXPERIMENTAL DESIGN:

We carried out single nucleotide polymorphism (SNP) and global gene expression array analyses, and/or immunohistochemical (IHC) analyses on 24 LGFMS tumor biopsies. Tumor types that are important differential diagnoses to LGFMS were included as comparison in the gene and protein expression analyses. In addition, cells that stably expressed FUS-CREB3L2 were analyzed with gene expression array and the influence of FUS-CREB3L2 on gene expression was investigated in vitro.

RESULTS:

The SNP array analysis detected recurrent microdeletions in association with the t(7;16) chromosomal breakpoints and gain of 7q in cases with ring chromosomes. Gene expression analysis clearly distinguished LGFMS from morphologically similar tumors and MUC4 was identified as a potential diagnostic marker for LGFMS by gene expression and IHC analysis. FOXL1 was identified as the top upregulated gene in LGFMS and CD24 was upregulated in both LGFMS tumors and FUS-CREB3L2 expressing cells. FUS-CREB3L2 was capable of activating transcription from CD24 regulatory sequences in luciferase assays, suggesting an important role for the upregulation of this gene in LGFMS.

CONCLUSIONS:

The gene expression profile of LGFMS is distinct from that of soft tissue tumors with similar morphology. The data could be used to identify a potential diagnostic marker for LGFMS and to identify possible FUS-CREB3L2 regulated genes.

©2011 AACR.