Characterization of gastric adenocarcinoma cell lines established from CEA424/SV40 T antigen-transgenic mice with or without a human CEAtransgene
© Nöckel et al; licensee BioMed Central Ltd. 2006
Received: 06 February 2006
Accepted: 14 March 2006
Published: 14 March 2006
Gastric carcinoma is one of the most frequent cancers worldwide. Patients with gastric cancer at an advanced disease stage have a poor prognosis, due to the limited efficacy of available therapies. Therefore, the development of new therapies, like immunotherapy for the treatment of gastric cancer is of utmost importance. Since the usability of existing preclinical models for the evaluation of immunotherapies for gastric adenocarcinomas is limited, the goal of the present study was to establish murine in vivo models which allow the stepwise improvement of immunotherapies for gastric cancer.
Since no murine gastric adenocarcinoma cell lines are available we established four cell lines (424GC, mGC3, mGC5, mGC8) from spontaneously developing tumors of CEA424/SV40 T antigen (CEA424/Tag) mice and three cell lines derived from double-transgenic offsprings of CEA424/Tag mice mated with human carcinoembryonic antigen (CEA)-transgenic (CEA424/Tag-CEA) mice (mGC2CEA, mGC4CEA, mGC11CEA). CEA424/Tag is a transgenic C57BL/6 mouse strain harboring the Tag under the control of a -424/-8 bp CEA gene promoter which leads to the development of invasive adenocarcinoma in the glandular stomach. Tumor cell lines established from CEA424/Tag-CEA mice express the well defined tumor antigen CEA under the control of its natural regulatory elements.
The epithelial origin of the tumor cells was proven by morphological criteria including the presence of mucin within the cells and the expression of the cell adhesion molecules EpCAM and CEACAM1. All cell lines consistently express the transgenes CEA and/or Tag and MHC class I molecules leading to their susceptibility to lysis by Tag-specific CTL in vitro. Despite the presentation of CTL-epitopes derived from the transgene products the tumor cell lines were tumorigenic when grafted into C57BL/6, CEA424/Tag or CEA424/Tag-CEA-transgenic hosts and no significant differences in tumor take and tumor growth were observed in the different hosts. Although no spontaneous tumor rejection was observed, vaccination of C57BL/6 mice with lysates from gastric carcinoma cell lines protected C57BL/6 mice from tumor challenge, demonstrating the tumorigenicity of the tumor cell lines in nontransgenic mice of the H-2b haplotype.
These tumor cell lines grafted in different syngeneic hosts should prove to be very useful to optimize immunotherapy regimens to be finally tested in transgenic animals developing primary gastric carcinomas.
Gastric cancer is the second most common cancer world-wide. It is often not detected until an advanced stage; consequently, the 5-year survival rates are low (10 to 20%). Owing to local invasion and metastasis, radiation therapy or chemotherapy does not significantly increase the length or quality of life of patients with advanced gastric cancer. Therefore, development of new neoadjuvant and adjuvant treatment modalities are needed. Immunotherapy might be a promising alternative option. A number of immunotherapy approaches like adoptive transfer of tumor-specific T cells, and vaccination using either undefined tumor antigens derived from tumor lysates and tumor cell lines or defined tumor antigens commonly presented by dendritic cells are being evaluated for various cancers[2, 3]. For gastric cancers, immunotherapy was not taken seriously into consideration due to the concept that gastric cancer is poorly immunogenic. Therefore, only a small number of clinical immunotherapy trials have been reported [4–7]. In addition, only a limited number of tumor-associated antigens with potential use for immunotherapy have been identified [8–11]. Consequently, the capability of the immune system to recognize and eradicate gastric cancers is largely unknown. To gain insight into the efficacy of various immunotherapies for the treatment of gastric cancer and to elucidate the underlying mechanism of induced immune responses animal models of gastric adenocarcinoma are indispensable.
To this end, several groups including ours have recently established transgenic or knock-out mouse strains which develop gastric adenomas or adenocarcinomas in various parts of the stomach after different latencies. We have developed a transgenic gastric carcinoma C57BL/6 mouse model based on a SV40 large T antigen (SV40 Tag) transgene controlled by a human carcinoembryonic antigen (CEA) gene promoter (from -424 to -8 of the translational start site). In 100% of the animals, dysplastic crypt formation in the stomach mucosa is observed in the pyloric region already in 30 day old CEA424/SV40 Tag-transgenic mice. Dysplasia progresses to invasive carcinomas and by day 50 the whole pyloric gastric mucosa has been replaced by carcinoma cells. Between the age of 90 to 110 days the transgenic mice become moribund and die probably of undernourishment due to blockage of the pylorus. The control of Tag expression by a minimal CEA gene promoter allows the tumor-directed expression of CEA by crossing CEA424/SV40 Tag-transgenic mice with human CEA-transgenic C57BL/6 mice, which express the CEA transgene in a similar spatiotemporal expression pattern as found in humans[13, 14]. The human tumor marker CEA is expressed in many human adenocarcinomas including more than 50% of gastric carcinomas[15, 16]. CEA is increasingly used as target antigen for a variety of antibody- and cell-mediated tumor immunotherapy approaches [17–19]. CEA and Tag are suitable immunotherapy target antigens since a number of T cell epitopes of these antigens have been identified in C57BL/6 mice [20–22]. Although these transgenic mouse strains mirror very closely gastric adenocarcinoma development in humans, experimentation with these mice is relatively time consuming and expensive due to the difficulties to determine tumor growth and the requirement of breeding transgenic mice. Therefore, it is desirable to have a syngeneic transplantable tumor system of gastric adenocarcinomas in immunocompetent mice for optimization of a given immunotherapy protocol before it is evaluated in the transgenic mice. Here we describe murine gastric adenocarcinoma cell lines established from spontaneously developing tumors of SV40 Tag-transgenic mice that are tumorigenic in both syngeneic wild type and transgenic mice.
Mouse strains and cell lines
CEA424/Tag-transgenic mice (C57BL/6-Tg(CEACAM5-Tag)L5496Wzm), CEA-transgenic mice (C57BL/6-Tg(CEACAM5)2682Wzm; CEA2682) and F1 mice from a cross between CEA424/Tag-transgenic and CEA-transgenic mice have been described previously [13, 14]. Meanwhile the transgenic lines have been backcrossed to C57BL/6 mice (H-2b) for more than 15 generations. The transgenic lines as well as C57BL/6 mice (Charles River, Sulzfeld, Germany) were bred and kept under standard pathogen-free conditions in the animal facility of the Institute for Surgical Research, Ludwig-Maximilians-University of Munich. The animal experiments were performed after approval by the local animal welfare committee. For tumorigenicity and immunogenicity assays mice were used at 8–12 weeks of age. African green monkey kidney Cos7L cell line was obtained from the American Tissue Culture Collection (ATCC, Rockville, MD). The BALB/c-derived fibrosarcoma Meth-A was kindly provided by W. Deppert (Heinrich-Pette-Institut, Hamburg). Meth-A-CEA cells were obtained by transfection of Meth-A cells with the pRc/CMV-CEA expression plasmids using FuGENE™ 6 transfection reagent (Roche Molecular Biochemicals, Switzerland) according to the manufacturer's instruction. Meth-A-cTag and RBL5/T transfectants were previously described.
Establishment of gastric carcinoma cell lines
The gastric carcinomas used to establish tumor cell lines were obtained from 8 different, 13 week-old mice. Four derived from CEA424/Tag-transgenic mice and 4 from CEA424/TAg-CEA-double transgenic mice. The names of the cell lines derived from the latter mice are marked by the superscript "CEA". All cultures were performed in RPMI1640 supplemented with 10% heat inactivated fetal calf serum (FCS "Gold"; PAA Laboratories, Coelbe, Germany), 2 mM L-glutamine, 100 U/ml penicillin, 100 μg/ml streptomycin, non-essential amino acids and 1 mM sodium pyruvate (GIBCO/Invitrogen, Karlsruhe, Germany), further referred to as tumor medium (TM). Tumor tissues were extensively washed in phosphate-buffered saline (PBS) supplemented with 200 μg/ml gentamicin and 2.5 μg/ml amphotericin B (GIBCO/Invitrogen), cut into 1 mm3 pieces with a scalpel and plated in tissue culture flasks containing TM. The culture medium was changed every 3–4 days. Epithelial cells and fibroblasts growing out of the tissue fragments were separated by cell scraping, selective trypsinization and selective passaging with 1,000 U/ml collagenase and 500 U/ml hyaluronidase (Biochrom, Berlin, Germany). During dissociation, the flasks were monitored under an inverted microscope and digestion was stopped when fibroblasts but not epithelial cells were detached (trypsin) or vice versa (collagenase/hyaluronidase). This procedure was repeated weekly until all fibroblasts were eliminated from the tumor cell cultures. During generation of the 424GC cell line, a fibroblast culture was established from contaminating fibroblasts (424 fibroblasts). Spheroids formed within 5–7 days after seeding 0.5 × 103 mGC8 cells into Noble agar (Sigma-Aldrich, Taufkirchen, Germany)-coated 96-well plates (TPP-Biochrom, Berlin, Germany) in 200 μl TM which was replaced with fresh medium every two days. To assess viability of cells on the surface of the spheroids, spheroids were incubated with FITC-labeled annexin V (Annexin V FITC Apoptosis Detection Kit; Calbiochem, Merck Biosciences, Darmstadt, Germany) for detection of apoptotic cells or with propidium iodide to identify necrotic cells according to the manufacturer's recommendations.
Flow cytometry analyses
For surface staining cells were trypsinized, washed with PBS and suspended in PBS/0.5% w/v bovine serum albumin (BSA) supplemented with 0.02% w/v sodium azide. For induction of MHC molecules, cells were incubated with 20 ng/ml of interferon-γ (IFNγ ; Peprotec, London, UK) for 24 hours prior harvesting. Non-specific binding of antibodies to Fc receptors was blocked by preincubation of the cells with 1 μg/106 cells of anti-CD16/CD32 monoclonal antibody (mAb) 2.4G2 (BD Pharmingen, Heidelberg, Germany) for 15 min. Subsequently the cells were incubated with 0.5 μg/106 cells of the mAb of interest for 30 min at 4°C, washed twice, and where appropriate, subsequently reacted with a second-step antibody for 15 min at 4°C. Cells were washed twice and analyzed using a FACScan (BD, Mountain View, CA). Dead cells were excluded by propidium iodide staining. The following reagents and mAbs against murine antigens from BD Pharmingen were used: phycoerythrin (PE)-conjugated mouse IgG2a anti-I-Ab, biotinylated mouse IgG2a anti-H-2Db, PE-conjugated mouse IgG2aanti-H-2Kb, PE-conjugated anti-mouse CD80/B7-1, PE-conjugated rat IgG2a anti-mouse CD40, PE-conjugated rat IgG2a anti-mouse CD86/B7-2, fluorescein isothiocyanate (FITC)-conjugated, Armenian hamster IgG2 anti-mouse CD80/B7-1. FITC-conjugated rat IgG1 mAb R3-34, PE-conjugated rat IgG1 mAb R3-34, PE-conjugated mouse IgG2a anti-rat SIRP, FITC-conjugated Armenian hamster IgG2anti-KLH and PE-conjugated rat IgG2amAb served as isotype controls. Mouse anti-mouse CEACAM1 mAb CC1, rat anti-mouse CEACAM1 AgB10  and rat anti-mouse E-cadherin and anti-mouse EpCAM mAbs were a kind gift from K. Holmes, University of Colorado, B. B. Singer, Charité Berlin, and P. Ruf, Trion Research, Munich, respectively. The cross-reactive mouse anti-human CEACAM mAb 4/3/17 (specific for human CEA/CEACAM5 in the mouse) were purchased from GENOVAC (Freiburg, Germany). Murine antibodies were detected with PE-conjugated goat anti-mouse IgG, rat antibodies with FITC-conjugated donkey anti-rat-IgG (DAKO).
Detection of CEA and SV40 Tag by Western blotting
Exponentially growing gastric carcinoma cells, Cos7L cells, Cos7L-CEA transfectants, Meth-A cells and Meth-A-cTag transfectants which express a truncated cytoplasmically located SV40 Tag were harvested by trypsinization. Cells were washed three times in PBS and lysed at a density of 106 cells/ml in lysis buffer. Protein concentration was determined using the BCA Protein Assay Kit (Pierce, Rockford, Illinois, USA). Cell extracts corresponding to 10 μg of protein were separated by electrophoresis through 10% SDS polyacrylamide gels (Invitrogen, Karlsruhe, Germany), transferred to polyvinyliden fluoride membranes and incubated with 10 μg/ml anti-human CEACAM mAb 4/3/17 or a 1:100 diluted hamster anti-SV40 Tag antiserum (a kind gift by K.-H. Scheidtmann, University of Bonn). Bound antibodies were reacted with horse-radish peroxidase-labeled secondary antibodies and visualized using a chemiluminescence-based detection system (ECL; Amersham Biosciences Europe GmbH, Freiburg, Germany).
Cell doubling time determination
In vitro doubling times of the cell lines were determined by plating the gastric carcinoma cells in 24-well plates in TM at the indicated starting cell numbers and counting of the cell samples from triplicate wells after gentle trypsinization every 3 days for 21 days. The in vivo doubling times were calculated from tumor volume measurements (see below) after inoculation with three different starting cell numbers (three mice per group). Doubling times were calculated from the log phase of the growth curves.
Tumorigenicity and immunogenicity of the cell lines
For tumorigenicity assessment tumor cells were washed three times in PBS and 50 μl of cell suspensions with the indicated cell numbers were injected subcutaneously into the shaved right flank of the mice. To determine the immunogenicity, 107 tumor cells/ml were lysed by two consecutive freeze and thaw cycles. Mice were immunized four times at weekly intervals with 106 lysed tumor cells into the right flank. Three weeks later, the mice were challenged by subcutaneous injection of 3 × 106 viable tumor cells into the left flank. Experimental groups consisted of 4–6 mice. Tumor development was followed by serial measurements of the tumor size and the tumor volume was calculated according to the equation: tumor volume (mm3) = d2 × D/2, where d and D were the shortest and the longest tumor diameter, respectively. Animals were euthanized when the tumors reached a volume of 300 mm3.
Generation of Tag-specific cytotoxic T lymphocytes (CTL) and stimulation by gastric carcinoma cell lines
CTLs were generated as previously described. Briefly, mice were intradermally inoculated with 1 μm gold particles coated with a Tag expression plasmid (BMG/cT-Ag.1 ) into the shaved abdominal skin using a helium pressure (200 psi) powered biolistic device (Helios gene gun; Bio-Rad Laboratories GmbH, Munich, Germany). Spleen cells obtained 14 days post vaccination were restimulated at weekly intervals with irradiated RBL5/T transfectants in RPMI-1640/10% FCS supplemented with 30 IU/ml IL-2. RBL5/T is a Rauscher virus-transformed T-lymphoma cell line derived from a C57BL6 (H-2b) mouse transfected with a SV40 Tag expression plasmid. To generate epitope-specific CTL, spleen cells taken 10 days post vaccination were restimulated in vitro with irradiated, Tag peptide-pulsed RBL5 cells. The T1, T2/3 and T4 epitope specificity of the CTL was controlled by determination of the IFNγ content of media upon stimulation with peptide-pulsed target cells using ELISA.
Cytokine detection by ELISA
For capture and detection of IFNγ in supernatants by conventional sandwich ELISA, we used mAb R4-6A2 and biotinylated mAb XMG1.2, respectively (BD Pharmingen). Extinction was analyzed at 405/490 nm on a TECAN microplate ELISA reader (TECAN Crailsheim, Germany) with the EasyWin software (TECAN). The detection limit of the ELISA for IFNγ was 20 pg/ml.
Establishment and phenotype of the gastric carcinoma cell lines
In order to determine the potential of the cell lines to be used for the generation of three-dimensional tumor models we analyzed tumor cell spheroid formation in vitro. As illustrated in Fig. 1B the cell lines formed compact tumor cell spheroids after 8 days of culture when 103 cells were seeded into soft agar-coated 96-well plates. Only minor intra-experimental variation was observed concerning the size of the spheroids. Staining with propidium iodide and FITC-labeled annexin V demonstrated that at least the surface layer of the spheroids consisted of viable cells with very few dead cells attached to it (Fig. 1B).
Transgene expression by the gastric carcinoma cell lines
Tumorigenicity of the gastric carcinoma cell lines
Immunogenicity of the gastric carcinoma cell lines
The main goal of the present study was to establish a therapeutic model of gastric cancer in immunocompetent mice that would provide an animal model to evaluate anti-tumor immunity and immunotherapeutic strategies. Towards this end, the murine cell lines described in this paper were established from spontaneously developing gastric tumors of two different transgenic mouse strains. Together with the transgenic mice, these cell lines now provide a useful experimental system for gastric cancer. A similar experimental system for prostate cancer, the TRAMP mice in combination with the C1 and C2 cell lines has already proven its great impact on prostate cancer research [25–27]. This is of particular importance, since in contrast to the large number of human gastric carcinoma cell lines to our knowledge only one murine gastric carcinoma cell line is available. This cell line was established from the forestomach but not from the glandular part of the stomach from which the most common carcinomas arise in humans.
The cell lines which we have established from CEA424/Tag-transgenic and CEA424/Tag-CEA-transgenic mice, have most likely originated from transformed gastric glandular epithelial cells for several reasons: all cell lines have an epithelial phenotype, contain reduced but detectable amounts of mucin, and express, with one exception (mGC11CEA), the epithelial cell marker EpCAM. The mGC11CEA cell line which was established from a CEA424/Tag-CEA-double transgenic mouse which expresses CEA, a molecule that is exclusively expressed by epithelial cells. Finally, all cell lines are tumorigenic and form tumors readily when transplanted subcutaneously into syngeneic mice (Fig. 5).
The murine gastric carcinoma cell lines as well as the primary gastric carcinomas mimic closely human gastric carcinomas and derived cell lines in expressing CEA (when established from tumor-bearing CEA-transgenic mice), upregulate CEACAM1, downregulate E-cadherin expression and express EpCAM. CEA has been found to increase tumorigenicity by blocking differentiation, inhibiting anoikis, a mechanism which results in destruction of epithelial cells once detached from their basement membrane and disrupting cell polarity. CEACAM1 is downregulated in colonic, prostate and mammary carcinomas and its re-expression reduces the tumorigenicity of epithelial tumor cell lines[36, 37]. Therefore, CEACAM1 is considered a tumor suppressor. On the other hand, CEACAM1 expression appears to be upregulated in subsets of other tumors like in stomach carcinomas in humans and mice[29, 30]. It was shown for melanoma and lung adenocarcinomas, that CEACAM1 upregulation is significantly associated with a poor prognosis[30, 38–40]. Furthermore, EpCAM has a direct effect on tumor cell proliferation by upregulation of c-myc and cyclin A/E and loss of E-cadherin expression is observed in undifferentiated-type gastric carcinomas upon mucosal spread and deep invasion beyond the submucosa. Taken together, these findings imply that similar molecular mechanisms are responsible for the tumorigenic properties of the murine gastric carcinoma cell lines as found for human gastric carcinomas and derived cell lines.
It is of particular relevance that the gastric cancer cell lines express different potential target antigens since the type of immunological tolerance may differ between different tumor antigens and between different transgenic strains. Indeed it was shown that depending on the expression pattern of Tag in different Tag-transgenic mice one can encounter all facets of immunological tolerance, ranging from immunological ignorance to central tolerance[25, 41–43]. There is strong evidence that also in CEA424/Tag mice central tolerance against the Tag exists (R. K., and W. Z., unpublished results). On the other hand, only a peripheral tolerance appears to exist for CEA in CEA2682-mice [44–47]. If needed, this allows testing of strategies to break tolerance to CEA without interference of the viral antigen Tag.
Finally, the cell lines generated from the transgenic mice have significant advantages to other subcutaneously transplantable CEA-expressing murine tumor cell lines, since in the transgenic cell lines CEA is expressed under the control of its naturally existing regulatory elements, which may be relevant in respect to possible immune escape mechanisms (i.e. escape variants).
For the optimization of tumor immunotherapy protocols, a series of in vivo models are needed which gradually make higher demands on the efficacy of the therapy. Ideally the whole series should be composed of the same cellular system and reach high relevance for the human disease for which immunotherapy is to be developed. The model system composed of wild-type C57BL/6, CEA424/Tag, CEA2682 and CEA424/Tag-CEA transgenic mice and the respective tumor cell lines described in the present report offers such a model for immunotherapies of gastric carcinoma. The established murine gastric adenocarcinoma cell lines may also be helpful for the identification of new tumor antigens relevant to gastric cancer as well as for the understanding of molecular events during gastric cancer progression.
SV40 virus large T antigen
The expert technical assistance by Anja Hennig, Michael Heide, Tanja Popp and Matthias Schiller is gratefully acknowledged. The CC1, AgB10, E-cadherin, EpCAM and SV40 Tag antibodies were kind gifts from K. Holmes, B. B. Singer, P. Ruf and K.-H. Scheidtmann. This work was supported by grants from the Deutsche Krebshilfe (70–2729) and the E. A. Chiles Foundation.
- Dicken BJ, Bigam DL, Cass C, Mackey JR, Joy AA, Hamilton SM: Gastric adenocarcinoma: review and considerations for future directions. Ann Surg. 2005, 241: 27-39.PubMedPubMed CentralGoogle Scholar
- Banchereau J, Palucka AK: Dendritic cells as therapeutic vaccines against cancer. Nat Rev Immunol. 2005, 5: 296-306. 10.1038/nri1592.View ArticlePubMedGoogle Scholar
- Overwijk WW: Breaking tolerance in cancer immunotherapy: time to ACT. Curr Opin Immunol. 2005, 17: 187-194. 10.1016/j.coi.2005.01.011.View ArticlePubMedGoogle Scholar
- Homma S, Matai K, Irie M, Ohno T, Kufe D, Toda G: Immunotherapy using fusions of autologous dendritic cells and tumor cells showed effective clinical response in a patient with advanced gastric carcinoma. J Gastroenterol. 2003, 38: 989-994. 10.1007/s00535-002-1183-3.View ArticlePubMedGoogle Scholar
- Kono K, Takahashi A, Ichihara F, Amemiya H, Iizuka H, Fujii H, Sekikawa T, Matsumoto Y: Prognostic significance of adoptive immunotherapy with tumor-associated lymphocytes in patients with advanced gastric cancer: a randomized trial. Clin Cancer Res. 2002, 8: 1767-1771.PubMedGoogle Scholar
- Yanai H, Kuroiwa Y, Shimizu N, Matsubara Y, Okamoto T, Hirano A, Nakamura Y, Okita K, Sekine T: The pilot experience of immunotherapy-combined photodynamic therapy for advanced gastric cancer in elderly patients. Int J Gastrointest Cancer. 2002, 32: 139-142. 10.1385/IJGC:32:2-3:139.View ArticlePubMedGoogle Scholar
- Matsumoto S, Saito H, Tsujitani S, Ikeguchi M: Allogeneic gastric cancer cell-dendritic cell hybrids induce tumor antigen (carcinoembryonic antigen) specific CD8+ T cells. Cancer Immunol Immunother. 2006, 55: 131-139. 10.1007/s00262-005-0684-3.View ArticlePubMedGoogle Scholar
- Niiya F, Nishizaka S, Matsunaga K, Koufuji K, Mori M, Katai H, Yamana H, Itoh K: Expression of SART3 tumor-rejection antigen in gastric cancers. Jpn J Cancer Res. 2000, 91: 337-342.View ArticlePubMedGoogle Scholar
- Sasada T, Takedatsu H, Azuma K, Koga M, Maeda Y, Shichijo S, Shoumura H, Hirai T, Takabayashi A, Itoh K: Immediate early response gene X-1, a stress-inducible antiapoptotic gene, encodes cytotoxic T-lymphocyte (CTL) epitopes capable of inducing human leukocyte antigen-A33-restricted and tumor-reactive CTLs in gastric cancer patients. Cancer Res. 2004, 64: 2882-2888. 10.1158/0008-5472.CAN-03-3549.View ArticlePubMedGoogle Scholar
- Inoue H, Mori M, Honda M, Li J, Shibuta K, Mimori K, Ueo H, Akiyoshi T: The expression of tumor-rejection antigen "MAGE" genes in human gastric carcinoma. Gastroenterology. 1995, 109: 1522-1525. 10.1016/0016-5085(95)90639-8.View ArticlePubMedGoogle Scholar
- Zhang HK, Zhang QM, Zhao TH, Li YY, Yi YF: Expression of mucins and E-cadherin in gastric carcinoma and their clinical significance. World J Gastroenterol. 2004, 10: 3044-3047.View ArticlePubMedPubMed CentralGoogle Scholar
- Pritchard DM, Przemeck SM: Review article: How useful are the rodent animal models of gastric adenocarcinoma?. Aliment Pharmacol Ther. 2004, 19: 841-859. 10.1111/j.1365-2036.2004.01911.x.View ArticlePubMedGoogle Scholar
- Thompson J, Epting T, Schwarzkopf G, Singhofen A, Eades-Perner AM, van Der PH, Zimmermann W: A transgenic mouse line that develops early-onset invasive gastric carcinoma provides a model for carcinoembryonic antigen-targeted tumor therapy. Int J Cancer. 2000, 86: 863-869. 10.1002/(SICI)1097-0215(20000615)86:6<863::AID-IJC16>3.0.CO;2-4.View ArticlePubMedGoogle Scholar
- Eades-Perner AM, van Der PH, Hirth A, Thompson J, Neumaier M, von Kleist S, Zimmermann W: Mice transgenic for the human carcinoembryonic antigen gene maintain its spatiotemporal expression pattern. Cancer Res. 1994, 54: 4169-4176.PubMedGoogle Scholar
- Chung JK, Choi CW, Lee MC, Chung HK, Kim NK, Choi KW, Koh CS: Radioimmunoscintigraphy of advanced gastrointestinal carcinomas employing I-131 labeled CEA-79 monoclonal antibody. Ann Nucl Med. 1993, 7: 65-70.View ArticlePubMedGoogle Scholar
- Tamai M, Tanimura H, Yamaue H, Iwahashi M, Tsunoda T, Tani M, Noguchi K, Mizobata S, Hotta T, Arii K, .: Clinical significance of quantitative analysis of carcinoembryonic antigen assessed by flow cytometry in fresh human gastric cancer cells. Cancer Lett. 1995, 90: 111-117. 10.1016/0304-3835(95)03695-S.View ArticlePubMedGoogle Scholar
- Horig H, Medina FA, Conkright WA, Kaufman HL: Strategies for cancer therapy using carcinoembryonic antigen vaccines. Expert Rev Mol Med. 2000, 2000: 1-24.Google Scholar
- Sarobe P, Huarte E, Lasarte JJ, Borras-Cuesta F: Carcinoembryonic antigen as a target to induce anti-tumor immune responses. Curr Cancer Drug Targets. 2004, 4: 443-454. 10.2174/1568009043332916.View ArticlePubMedGoogle Scholar
- Babatz J, Rollig C, Lobel B, Folprecht G, Haack M, Gunther H, Kohne CH, Ehninger G, Schmitz M, Bornhauser M: Induction of cellular immune responses against carcinoembryonic antigen in patients with metastatic tumors after vaccination with altered peptide ligand-loaded dendritic cells. Cancer Immunol Immunother. 2006, 55: 268-276. 10.1007/s00262-005-0021-x.View ArticlePubMedGoogle Scholar
- Mylin LM, Bonneau RH, Lippolis JD, Tevethia SS: Hierarchy among multiple H-2b-restricted cytotoxic T-lymphocyte epitopes within simian virus 40 T antigen. J Virol. 1995, 69: 6665-6677.PubMedPubMed CentralGoogle Scholar
- Mylin LM, Schell TD, Roberts D, Epler M, Boesteanu A, Collins EJ, Frelinger JA, Joyce S, Tevethia SS: Quantitation of CD8(+) T-lymphocyte responses to multiple epitopes from simian virus 40 (SV40) large T antigen in C57BL/6 mice immunized with SV40, SV40 T-antigen-transformed cells, or vaccinia virus recombinants expressing full-length T antigen or epitope minigenes. J Virol. 2000, 74: 6922-6934. 10.1128/JVI.74.15.6922-6934.2000.View ArticlePubMedPubMed CentralGoogle Scholar
- Schmitz J, Reali E, Hodge JW, Patel A, Davis G, Schlom J, Greiner JW: Identification of an interferon-gamma-inducible carcinoembryonic antigen (CEA) CD8(+) T-cell epitope, which mediates tumor killing in CEA transgenic mice. Cancer Res. 2002, 62: 5058-5064.PubMedGoogle Scholar
- Kammerer R, Stober D, Riedl P, Oehninger C, Schirmbeck R, Reimann J: Noncovalent association with stress protein facilitates cross-priming of CD8+ T cells to tumor cell antigens by dendritic cells. J Immunol. 2002, 168: 108-117.View ArticlePubMedGoogle Scholar
- Kuprina NI, Baranov VN, Yazova AK, Rudinskaya TD, Escribano M, Cordier J, Gleiberman AS, Goussev AI: The antigen of bile canaliculi of the mouse hepatocyte: identification and ultrastructural localization. Histochemistry. 1990, 94: 179-186.View ArticlePubMedGoogle Scholar
- Foster BA, Gingrich JR, Kwon ED, Madias C, Greenberg NM: Characterization of prostatic epithelial cell lines derived from transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Cancer Res. 1997, 57: 3325-3330.PubMedGoogle Scholar
- Williams TM, Hassan GS, Li J, Cohen AW, Medina F, Frank PG, Pestell RG, Di Vizio D, Loda M, Lisanti MP: Caveolin-1 promotes tumor progression in an autochthonous mouse model of prostate cancer: genetic ablation of Cav-1 delays advanced prostate tumor development in tramp mice. J Biol Chem. 2005, 280: 25134-25145. 10.1074/jbc.M501186200.View ArticlePubMedGoogle Scholar
- Xiao D, Zeng Y, Choi S, Lew KL, Nelson JB, Singh SV: Caspase-dependent apoptosis induction by phenethyl isothiocyanate, a cruciferous vegetable-derived cancer chemopreventive agent, is mediated by Bak and Bax. Clin Cancer Res. 2005, 11: 2670-2679. 10.1158/1078-0432.CCR-04-1545.View ArticlePubMedGoogle Scholar
- Qian SS, Gao J, Wang JX, Liu Y, Dong HY: [Establishment of a mouse forestomach carcinoma cell line (MFC) with spontaneous hematogenous metastasis and preliminary study of its biological characteristics]. Zhonghua Zhong Liu Za Zhi. 1987, 9: 261-264.PubMedGoogle Scholar
- Kinugasa T, Kuroki M, Takeo H, Matsuo Y, Ohshima K, Yamashita Y, Shirakusa T, Matsuoka Y: Expression of four CEA family antigens (CEA, NCA, BGP and CGM2) in normal and cancerous gastric epithelial cells: up-regulation of BGP and CGM2 in carcinomas. Int J Cancer. 1998, 76: 148-153. 10.1002/(SICI)1097-0215(19980330)76:1<148::AID-IJC23>3.0.CO;2-7.View ArticlePubMedGoogle Scholar
- Zebhauser R, Kammerer R, Eisenried A, McLellan A, Moore T, Zimmermann W: Identification of a novel group of evolutionarily conserved members within the rapidly diverging murine Cea family. Genomics. 2005, 86: 566-580. 10.1016/j.ygeno.2005.07.008.View ArticlePubMedGoogle Scholar
- Nakamura E, Sugihara H, Bamba M, Hattori T: Dynamic alteration of the E-cadherin/catenin complex during cell differentiation and invasion of undifferentiated-type gastric carcinomas. J Pathol. 2005, 205: 349-358. 10.1002/path.1718.View ArticlePubMedGoogle Scholar
- Munz M, Kieu C, Mack B, Schmitt B, Zeidler R, Gires O: The carcinoma-associated antigen EpCAM upregulates c-myc and induces cell proliferation. Oncogene. 2004, 23: 5748-5758. 10.1038/sj.onc.1207610.View ArticlePubMedGoogle Scholar
- Eidelman FJ, Fuks A, DeMarte L, Taheri M, Stanners CP: Human carcinoembryonic antigen, an intercellular adhesion molecule, blocks fusion and differentiation of rat myoblasts. J Cell Biol. 1993, 123: 467-475. 10.1083/jcb.123.2.467.View ArticlePubMedGoogle Scholar
- Ordonez C, Screaton RA, Ilantzis C, Stanners CP: Human carcinoembryonic antigen functions as a general inhibitor of anoikis. Cancer Res. 2000, 60: 3419-3424.PubMedGoogle Scholar
- Ilantzis C, DeMarte L, Screaton RA, Stanners CP: Deregulated expression of the human tumor marker CEA and CEA family member CEACAM6 disrupts tissue architecture and blocks colonocyte differentiation. Neoplasia. 2002, 4: 151-163. 10.1038/sj.neo.7900201.View ArticlePubMedPubMed CentralGoogle Scholar
- Luo W, Tapolsky M, Earley K, Wood CG, Wilson DR, Logothetis CJ, Lin SH: Tumor-suppressive activity of CD66a in prostate cancer. Cancer Gene Ther. 1999, 6: 313-321. 10.1038/sj.cgt.7700055.View ArticlePubMedGoogle Scholar
- Turbide C, Kunath T, Daniels E, Beauchemin N: Optimal ratios of biliary glycoprotein isoforms required for inhibition of colonic tumor cell growth. Cancer Res. 1997, 57: 2781-2788.PubMedGoogle Scholar
- Laack E, Nikbakht H, Peters A, Kugler C, Jasiewicz Y, Edler L, Brummer J, Schumacher U, Hossfeld DK: Expression of CEACAM1 in adenocarcinoma of the lung: a factor of independent prognostic significance. J Clin Oncol. 2002, 20: 4279-4284. 10.1200/JCO.2002.08.067.View ArticlePubMedGoogle Scholar
- Sienel W, Dango S, Woelfle U, Morresi-Hauf A, Wagener C, Brummer J, Mutschler W, Passlick B, Pantel K: Elevated expression of carcinoembryonic antigen-related cell adhesion molecule 1 promotes progression of non-small cell lung cancer. Clin Cancer Res. 2003, 9: 2260-2266.PubMedGoogle Scholar
- Thies A, Moll I, Berger J, Wagener C, Brummer J, Schulze HJ, Brunner G, Schumacher U: CEACAM1 expression in cutaneous malignant melanoma predicts the development of metastatic disease. J Clin Oncol. 2002, 20: 2530-2536. 10.1200/JCO.2002.05.033.View ArticlePubMedGoogle Scholar
- Schell TD, Mylin LM, Georgoff I, Teresky AK, Levine AJ, Tevethia SS: Cytotoxic T-lymphocyte epitope immunodominance in the control of choroid plexus tumors in simian virus 40 large T antigen transgenic mice. J Virol. 1999, 73: 5981-5993.PubMedPubMed CentralGoogle Scholar
- Soldevila G, Geiger T, Flavell RA: Breaking immunologic ignorance to an antigenic peptide of simian virus 40 large T antigen. J Immunol. 1995, 155: 5590-5600.PubMedGoogle Scholar
- Zheng X, Gao JX, Zhang H, Geiger TL, Liu Y, Zheng P: Clonal deletion of simian virus 40 large T antigen-specific T cells in the transgenic adenocarcinoma of mouse prostate mice: an important role for clonal deletion in shaping the repertoire of T cells specific for antigens overexpressed in solid tumors. J Immunol. 2002, 169: 4761-4769.View ArticlePubMedGoogle Scholar
- Hance KW, Zeytin HE, Greiner JW: Mouse models expressing human carcinoembryonic antigen (CEA) as a transgene: evaluation of CEA-based cancer vaccines. Mutat Res. 2005, 576: 132-154.View ArticlePubMedPubMed CentralGoogle Scholar
- Saha A, Baral RN, Chatterjee SK, Mohanty K, Pal S, Foon KA, Primus FJ, Krieg AM, Weiner GJ, Bhattacharya-Chatterjee M: CpG oligonucleotides enhance the tumor antigen-specific immune response of an anti-idiotype antibody-based vaccine strategy in CEA transgenic mice. Cancer Immunol Immunother. 2005, [Epub ahead of print]: 1-13.Google Scholar
- Schwegler C, Dorn-Beineke A, Nittka S, Stocking C, Neumaier M: Monoclonal anti-idiotype antibody 6G6.C4 fused to GM-CSF is capable of breaking tolerance to carcinoembryonic antigen (CEA) in CEA-transgenic mice. Cancer Res. 2005, 65: 1925-1933. 10.1158/0008-5472.CAN-04-3591.View ArticlePubMedGoogle Scholar
- Xiang R, Silletti S, Lode HN, Dolman CS, Ruehlmann JM, Niethammer AG, Pertl U, Gillies SD, Primus FJ, Reisfeld RA: Protective immunity against human carcinoembryonic antigen (CEA) induced by an oral DNA vaccine in CEA-transgenic mice. Clin Cancer Res. 2001, 7: 856s-864s.PubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2407/6/57/prepub
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