Monoclonal antibody raised by sera of athymic mice bearing human lung cancer xenografts

A monoclonal antibody, NCC-LU-165 (IgM, k), was obtained by somatic cell hybridization between mouse myeloma cells (P3-X63-Ag8-U1) and spleen cells of an immunocompetent mouse (BALB/c, nu/+) immunized with sera of immunodeficient athymic mice (BALB/c, nu/nu) bearing human giant cell lung cancer xenografts (Lu65). Immunohistochemically, the antibody was reactive with most nonsmall cell carcinoma of the lung. It also reacted with adenocarcinoma of the stomach, colon, pancreas and breast. Antigens were detected in sera of athymic mice bearing human lung cancer xenografts and in cell-free conditioned media of Lu65 cells by a sandwich enzyme immunoassay. This immunization method may be useful to raise monoclonal antibodies that detect circulating tumor-associated antigen.     

A novel method for the detection of necrotic lesions in human cancers

Data are presented in support of the hypothesis that malignant tumors, containing abnormally permeable, degenerating cells, can be selectively detected using monoclonal antibodies to intracellular antigens. Biodistribution, imaging, and autoradiographic studies were performed in nude mice transplanted with four different human tumor cell lines to demonstrate the binding of radiolabeled antinuclear monoclonal antibodies within bulky tumors containing necrotic lesions. For these studies, two monoclonal antibodies, designated TNT-1 (IgG2a) and TNT-2 (IgM) were chosen since they were found to bind to abundant nuclear antigens which are retained in permeable, dying cells. F(ab')2 fragments prepared by pepsin digestion were radiolabeled with iodine-125 or iodine-131 by the iodogen method for i.v. administration. Biodistribution studies in nontumor-bearing BALB/c mice at various time intervals revealed normal patterns of antibody excretion with no accumulation of antibody in healthy organs. In contrast, biodistribution studies performed on Day 3 in tumor-bearing nude mice showed high tumor to organ ratios in those animals bearing necrotic tumors. Necrotic regions dissected at necropsy gave tumor to blood ratios as high as 131:1. Transplants having little demonstrable necrosis were found to have low tumor to blood ratios (0.4:1). Sequential imaging studies confirmed the high tumor-to-organ ratios and showed positive tumor imaging as early as 4 h. Autoradiographic studies of excised tumors showed the presence of label selectively in necrotic areas with preferential labeling over the nuclei of degenerating cells. Because of the universal presence of these nuclear antigens and the known prevalence of necrosis in tumors, this approach may be of value for the imaging and treatment of a wide variety of cancers in humans.     

Anti-CD74 antibody-doxorubicin conjugate, IMMU-110, in a human multiple myeloma xenograft and in monkeys.

PURPOSE: IMMU-110 is a drug immunoconjugate composed of doxorubicin conjugated to the humanized anti-CD74 monoclonal antibody, hLL1, at a doxorubicin/monoclonal antibody ratio of approximately 8:1 (mol/mol). CD74 is a rapidly internalizing molecule associated with HLA-DR, which has high expression by several tumor types. Here, we describe safety evaluations of IMMU-110 in mice and monkeys as well as efficacy studies in a xenograft model of the human multiple myeloma cell line, MC/CAR. EXPERIMENTAL DESIGN: In vitro binding of IMMU-110 was determined by a cell-based ELISA and cytotoxicity of IMMU-110 assayed with a tetrazolium assay. Pharmacokinetics and biodistribution of radiolabeled IMMU-110 were examined in tumor-free BALB/c mice, and the therapeutic effectiveness was evaluated in severe combined immunodeficient mice bearing MC/CAR cells. Acute toxicity of IMMU-110 was studied in CD74-positive cynomolgus monkeys (Macaca fascicularis). RESULTS: In vitro, IMMU-110 specifically binds to CD74 and is cytotoxic against MC/CAR cells. In vivo, IMMU-110 displayed a pharmacokinetic and biodistribution profile identical to that of unconjugated hLL1 monoclonal antibody, except for higher kidney uptake. Treatment with a single dose of IMMU-110 as low as 50 microg antibody/mouse (or 1.4 microg doxorubicin/mouse), 5 days postinjection of the multiple myeloma cells, resulted in cure of most mice. In mice, no host toxicity of IMMU-110 was observed at the highest protein dose tested (125 mg/kg). In cynomolgus monkeys, bone marrow toxicity was observed at 30 and 90 mg/kg doses. CONCLUSIONS: The excellent safety and efficacy profile of IMMU-110 supports clinical testing of this immunoconjugate in the treatment of CD74-positive B-cell malignancies.     

Evaluation of novel antimouse VEGFR2 antibodies as potential antiangiogenic or vascular targeting agents for tumor therapy

We generated a panel of eight rat IgG(2a) monoclonal antibodies with high affinity for mouse VEGFR2 (KDR/Flk-1), the main receptor that mediates the angiogenic effect of VEGF-A. The antibodies (termed RAFL, R at Anti Flk) bound to dividing endothelial cells more strongly than they did to nondividing cells. Most of the RAFL antibodies blocked [(125)I]VEGF(165) binding to VEGFR2. Three of eight antibodies localized to VEGFR2-positive tumor endothelium after intravenous injection into mice bearing orthotopic MDA-MB-231 breast carcinomas, as judged by indirect immunohistochemistry. An average of 60% of vessels in the tumors was stained. The majority (50-80%) of vessels were also stained in a variety of other human and murine tumors growing in mice. The antibodies did not bind detectably to the vascular endothelium in normal heart, lung, liver, and brain cortex, whereas the vascular endothelium in kidney glomerulus and pancreatic islets was stained. Treatment of mice bearing orthotopic MDA-MB-231 tumors with RAFL-1 antibody inhibited tumor growth by an average of 48% and reduced vascular density by 65%, compared to tumors in mice treated with control IgG. Vascular damage was not observed in normal organs, including kidneys and pancreas. These studies demonstrate that anti-VEGFR2 antibodies have potential for vascular targeting and imaging of tumors in vivo.     

Preclinical studies on the pharmacokinetic properties of human monoclonal antibodies to colorectal cancer and their use for detection of tumors

We studied the pharmacokinetic properties of two human monoclonal antibodies to colon carcinoma cells and their ability to detect tumors in nude mice bearing primary human colon carcinoma xenografts. The 16-88 and 28A32 monoclonal antibodies are immunoglobulin M class human antibodies produced by cell lines derived from peripheral blood lymphocytes from patients with colon carcinoma. The patients received an autologous tumor cell vaccine as part of an active specific immunotherapy protocol. The 125I-labeled antibodies were cleared from the circulation of non-tumor-bearing and tumor-bearing nude mice with a 6-8-h half-life. The half-life of the antibodies in tumor tissue was 48 to 72 h compared to 8 to 12 h for normal tissues. Tumor:normal tissue ratios were highest 4 to 7 days postinjection with tumor:blood ratios of 12:1 for 16-88 and 10:1 for 28A32 antibody. Experiments with a control human immunoglobulin M myeloma protein confirmed the specificity of the human monoclonal antibodies. Radioimmunoscintigraphic studies using nude mice bearing contralateral antibody-reactive and nonreactive colon tumor xenografts further confirmed that the antibodies specifically localized in tumor tissues. The antibody-reactive tumors were clearly visible by radioimmunoscintigraphy within 4 days of injection. These experiments, undertaken as a preliminary step to clinical trials, demonstrated for the first time that i.v. administered human immunoglobulin M monoclonal antibodies could be taken up by human colon tumor tissue and retained to a sufficient extent to easily permit tumor detection by external radioimmunoscintigraphy. These studies also demonstrated that the nude mouse human colon tumor xenograft model is a useful in vivo system for comparison studies of human monoclonal antibodies as part of a selection process for clinical trials and for evaluating immunoconjugates containing these antibodies for relative pharmacokinetic properties and potential diagnostic or therapeutic efficacy.     

Importance of Lyt 1+ T-cells in the antitumor activity of an immunomodulator, SSM, extracted from human-type Tubercle bacilli

An arabinomannan lipid extracted from Mycobacterium tuberculosis strain Aoyama B (SSM) is an immunopotentiating agent with interferon-inducing and antitumor activities. In the present study, the possible role(s) of various immunocompetent cells on the antitumor effect of SSM was investigated in mice bearing syngeneic (RL male 1 leukemia) and allogeneic (Ehrlich carcinoma) ascites tumors. When Thy 1+ T-cells were depleted from tumor-bearing mice by the administration of monoclonal anti-Thy 1.2 antibody, the protective effect of SSM was eliminated. However, when macrophage (M phi) and natural killer (NK) cell activities were depleted by treatment with M phi blockers (trypan blue and carrageenan) or a blocker for NK cells (anti-asialo GM1 antiserum), no alteration of the antitumor activity of SSM was observed. Therefore, T-lymphocytes, but not M phi or NK cells, were required for the expression of the antitumor efficacy of SSM. The antitumor activity of SSM was also abrogated by Lyt 1+ T-cells being depleted by treatment with monoclonal anti-Lyt 1.2 antibody, whereas the administration of monoclonal anti-Lyt 2.2 antibody had no effect on the antitumor activity. Independent of M phi, NK cells, or Lyt 2+ T-cells, Lyt 1+ T-lymphocytes appear to play an important role in the expression of the antitumor effects of SSM.     

CXCR4 neutralization,a novel therapeutic approach for non-Hodgkin's lymphoma

The chemokine stromal cell-derived factor-1 (CXCL12/SDF-1) and its monogamous receptor CXCR4 are involved in trafficking of B cells and hematopoietic progenitors. CXCR4 expression was found in the large majority of non-Hodgkin's lymphoma (NHL) cell lines and primary cells, and CXCR4 neutralization by monoclonal antibodies had profound in vitro effects on NHL cells including inhibition of transendothelial/stromal migration, enhanced apoptosis, decreased proliferation, and inhibition of pseudopodia formation. In a nonobese diabetes/severe combined immunodeficiency (NOD/SCID) mouse model of human high-grade NHL, CXCR4 neutralization had an impressive efficacy. In a first tumor-challenge trial, CXCR4 neutralization of Namalwa cells injected i.p. delayed tumor growth and reduced tumor weight. In a second tumor-challenge trial, NOD/SCID mice received Namalwa cells i.v. All of the controls died of neoplasia within day 36, whereas 83% of mice injected with cells incubated with anti-CXCR4 were still alive and disease-free >150 days after transplant. The crucial role of CXCR4 in tumor cell extravasation was confirmed by the finding that CXCR4 neutralization before i.v. injection of Namalwa cells in NOD/SCID mice increased the number of cancer cells circulating 24 h after injection. In additional preclinical trials, the therapeutic effect of anti-CXCR4 antibodies was evaluated in mice bearing Namalwa cells injected 3 days before. Tumor growth was abrogated in the majority of treated mice and significantly delayed in the remaining group. Taken together, these data support clinical studies on CXCR4 neutralization in NHL patients by monoclonal antibodies or CXCR4 antagonists.     

Effective cancer targeting using an anti-tumor tissue vascular endothelium-specific monoclonal antibody (TES-23).

Immunoconjugate targeting of solid tumors has not been routinely successful because the endo-thelial cells of blood vessels act as a physical barrier against the transport of macromolecules, such as antibodies. In the present study, we attempted to achieve tumor vascular targeting with an anti-tumor tissue endothelium-specific monoclonal antibody (TES-23). TES-23, an IgG1 monoclonal antibody raised against rat KMT-17 fibrosarcoma-derived endothelial cells, was covalently conjugated with neocarzinostatin (NCS) in a previous study. The TES-23-NCS conjugate induced tumor hemorrhagic necrosis, and showed marked anti-tumor effects against rat KMT-17 fibrosarcoma. This result prompted us to investigate whether this approach would be applicable to various other types of solid tumors. One hour after injection of (125)I-labeled TES-23 into BALB / c mice bearing Meth-A fibrosarcoma and Colon 26 adenocarcinoma, the tumor accumulation of TES-23 was greater than that of the control IgG. In the present study, we report the anti-tumor effects of this monoclonal antibody in mice bearing Meth-A fibrosarcoma. Mice treated with the immunoconjugate showed improved survival with no side effects. This result indicates that common antigens may be found in different kinds of tumor endothelial cells, and that TES-23 might recognize these antigens.     

Serotherapy of L1210 murine leukaemia--reasons for ineffectiveness of in vivo treatment by L.1 monoclonal antibody.

A monoclonal antibody (L.1), reacting in vitro specifically with L1210 leukaemia cells in a complement-dependent cytotoxicity assay (CDC), has been exploited for serotherapy studies. Different regiments of L.1 treatment of CD2F1 mice bearing the semi-syngeneic L1210 leukaemia did not prolong the life span of tumor-bearing animals. Moreover, the administration of L.1 did not enhance the antitumour effects of cyclophosphamide. Studies of in vivo localization showed that L.1 was able to bind specifically to L1210 leukaemic cells, although 30-40% of the cells remained negative. The presence of L.1 in mouse blood was demonstrated up to 15 days after the inoculation. On the other hand, in vivo administration of L.1 was probably accompanied by loss of the cytotoxic activity, perhaps through a mechanism of complement inactivation, since the presence of undiluted normal mouse serum in a CDC assay inhibited the cytotoxic activity of L.1. Moreover, serum from L.1-treated mice did not display any cytotoxic activity, although the presence of the antibody could be demonstrated by indirect immunofluorescence. Shedding of the antigen defined by L.1 was probably not responsible for the failure of the serotherapy, since the L.1 neutralizing antigen could be found in body fluids only long after the start of therapy.     

Effective Cancer Targeting Using an Anti-tumor Tissue Vascular Endotheliumspecific Monoclonal Antibody (TES-23)

Immunoconjugate targeting of solid tumors has not been routinely successful because the endothelial cells of blood vessels act as a physical barrier against the transport of macromolecules, such as antibodies. In the present study, we attempted to achieve tumor vascular targeting with an antitumor tissue endothelium-specific monoclonal antibody (TES-23). TES-23, an IgG1 monoclonal antibody raised against rat KMT-17 fibrosarcoma-derived endothelial cells, was covalently conjugated with neocarzinostatin (NCS) in a previous study. The TES-23-NCS conjugate induced tumor hemorrhagic necrosis, and showed marked anti-tumor effects against rat KMT-17 fibrosarcoma. This result prompted us to investigate whether this approach would be applicable to various other types of solid tumors. One hour after injection of ¹²⁵I-labeled TES-23 into BALB/c mice bearing Meth-A fibrosarcoma and Colon 26 adenocarcinoma, the tumor accumulation of TES-23 was greater than that of the control IgG. In the present study, we report the anti-tumor effects of this monoclonal antibody in mice bearing Meth-A fibrosarcoma. Mice treated with the immunoconjugate showed improved survival with no side effects. This result indicates that common antigens may be found in different kinds of tumor endothelial cells, and that TES-23 might recognize these antigens.     

The role of immune factors in the survival of circulating tumor cells.

The effects of immune serum on the survival of hematogenously disseminated malignant cells were investigated in six murine tumor systems with varying immunogenicity. Blood containing circulating tumor cells demonstrable by bioassay was obtained from donor mice with disseminated tumor. The cellular fraction was isolated by centrifugation and resuspended in immune serum obtained from donor animals bearing the same tumor (Group 1), in immune serum from mice bearing a differing tumor (Group 2), or in normal nonimmune serum (Group 3). The mixed cellular and serum fractions were intravenously inoculated into normal recipient mice which were subsequently scored for the development of pulmonary tumors. Similar incidence (35-50%) of pulmonary tumor deposits were seen in Groups 2 and 3. A significant enhancement in the incidence of lung tumors was present in the Group 1 animals for all tumor systems studies. It was suggested that the observed enhancement resulted from factors present in isologous immune serum but absent from both normal serum and immune serum obtained from hosts bearing heterologous tumors.     

Prolonged survival of mice with human gastric cancer treated with an anti-c-ErbB-2 monoclonal antibody.

A monoclonal antibody (MAb), 4D5, specifically recognising an extracellular epitope of the c-ErbB-2 protein, inhibited the growth of human gastric cancer overexpressing c-ErbB-2 severe combined immunodeficient (SCID) mice. This antibody also reduced the mass of established tumours xenografted into SCID mice, whereas gastric cancer not expressing c-ErbB-2 exhibited no regression in response to 4D5 treatment. In addition, administration of 4D5 prevented colonisation of cancer cells and prolonged the survival of host SCID mice inoculated i.v. with c-ErbB-2-overexpressing tumour cells. This is the first reported study to show that treatment with a single antibody specific to c-ErbB-2 prolongs the survival of host SCID mice bearing xenotransplanted tumours.     

Reversal of drug resistance in a human colon cancer xenograft expressing MDR1 complementary DNA by in vivo administration of MRK-16 monoclonal antibody.

One strategy to overcome multidrug resistance in neoplasia is to inhibit the gp170 glycoprotein (relative molecular mass, 170,000) that functions as a plasma membrane, energy-dependent, drug-efflux pump. The human colon cancer cell line HT-29, which grows as an ascitic tumor in athymic NCr-nu/nu nude mice, was made multidrug resistant by infection with an MDR1 (also known as PGY1) retrovirus. Referred to as HT-29mdr1, it was used to study reversal of drug resistance in vivo by the anti-P-glycoprotein monoclonal antibody MRK-16. Flow cytometry and radioimmunoassay demonstrated a marked increase in MRK-16 reactivity on HT-29mdr1 cells as compared with its reactivity on the parental, uninfected cell line (HT-29par). The 50% inhibitory concentrations (IC50) of vincristine on HT-29par and HT-29mdr1 cells were 2.5 and 15 ng/mL, respectively. The MRK-16 monoclonal antibody did not affect the vincristine sensitivity of the HT-29par cells. Pretreatment of HT-29mdr1 cells with 10 micrograms/mL MRK-16 in tissue culture partially restored the vincristine sensitivity (IC50 = 7 ng/mL). This modulation of vincristine sensitivity by MRK-16 was then tested in vivo. The median survival times of mice given intraperitoneal transplants of 5 x 10(6) HT-29par or HT-29mdr1 were 37 and 39 days, respectively. Treatment of mice with 1 mg/kg vincristine weekly for 3 weeks, beginning 10 days after tumor injection, resulted in a significant increase in the median survival time of the HT-29par tumor-bearing mice (68 days, P less than .0001), but it had no effect on the HT-29mdr1 tumor-bearing mice. However, treatment of mice bearing the HT-29mdr1 tumor with MRK-16 before vincristine therapy reversed the resistance to the drug (median survival time = 64 days, P less than .0001). The MRK-16 monoclonal antibody alone had no effect on the median survival time of mice given an injection of either HT-29par or HT-29mdr1 cells. These results suggest that strategies employing monoclonal antibody against gp170 may be clinically useful to reverse multidrug resistance.     

NRP-1单抗联合节律化疗对裸鼠胃癌移植瘤生长的抑制

目的：探讨NRP-1 单抗联合多西他赛节律化疗对胃癌裸鼠移植瘤的抗肿瘤疗效。方法：BALB/c裸鼠皮下接种胃癌BGC-823 细胞制备移植瘤模型,将荷瘤裸鼠以数字随机表法随机分为对照组、NRP-1 单抗组、节律化疗组(MCT)、联合组(NRP-1mAb+MCT),每组6 只。除对照组,其余各组于造模第8 天开始分别给予相应治疗,给药2 周,观察裸鼠一般状况,隔天测量裸鼠体重及肿瘤体积。裸鼠处死后称瘤质量,H-E 染色观察瘤组织形态,免疫组化检测裸鼠瘤组织中NRP-1 蛋白、VEGF、MVD表达。结果：联合组移植瘤的体积和质量显著低于其他各组[ （0.394±0.128）vs（0.748±0.152）、0.867±0.361）、（1.247±0.494）g;（0.613±0.223) vs (0.866±0.115)、(1.098±0.343)、(1.474±0.644) cm3。均P<0.05],抑瘤率较其他治疗组差异有统计学意义(P<0.05)。对照组癌组织细胞生长良好,血管丰富,给药组癌组织出现不同程度的片状坏死,血管成分减少。免疫组化染色显示,对照组NRP-1 表达明显高于治疗各组(P<0.05),联合组的NRP-1、VEGF、MVD表达均显著低于其余各组(P<0.05)。结论：NRP-1单抗联合多西他赛节律化疗可能通过下调NRP-1 表达而显著抑制BGC-823 胃癌移植瘤的生长及血管生成。     

CpG‐ODN increases the release of VEGF in a mouse model of lung carcinoma

Vascular endothelial‐derived growth factor (VEGF) plays a fundamental role in the formation of new vessels within the tumour mass. Increasing evidence has highlighted the involvement of Toll‐like receptors (TLRs) in cancer. Of interest, TLR9 is over‐expressed in human lung carcinoma tissues. The aim of our study was to determine whether TLR9 activation could alter VEGF release in a mouse model of lung carcinoma. Lewis lung carcinoma cells were intravenously (i.v.) inoculated and 10 days later, tumour‐bearing mice were treated with CpG‐ODN (CpG, a TLR9 ligand) or PBS. CpG administration enhanced VEGF release, which was associated with increased tumour lesions in the lung. CpG induced high levels of IL‐6 expression and activation of STAT3 in tumour‐bearing mice. Moreover, CpG induced VEGF release from primary fibroblasts and endothelial cells, which correlated with IL‐6 and TGFβ production. This may explain the large influx of fibroblasts and the production of basic fibroblast growth factor (bFGF) in the tumour mass. The administration of a monoclonal antibody against VEGF A arrested tumour progression and induced a Th1‐like response in CpG‐treated tumour‐bearing mice. In conclusion, our study demonstrates that the combination of CpG with anti‐VEGF monoclonal antibody could be of potential therapeutic in lung carcinoma.     

Activating Fc receptors are required for antitumor efficacy of the antibodies directed toward CD25 in a murine model of adult t-cell leukemia

We previously showed therapeutic efficacy of humanized anti-Tac (HAT), murine anti-Tac (MAT), and 7G7/B6 monoclonal antibodies, which recognize CD25, for human adult T-cell leukemia (ATL) in a murine model. In this study, we investigated the mechanism underlying the tumor-killing action mediated by these antibodies on an ATL model in nonobese diabetic/severe combined immunodeficient (SCID/NOD) wild-type mice that lack effective T and natural killer (NK) cells and in SCID/NOD Fc receptor common gamma chain knockout (FcRgamma-/-) mice. The ATL model was established by i.p. injection of human ATL cells (MET-1) into SCID/NOD wild-type or SCID/NOD FcRgamma-/- mice. HAT, MAT, and 7G7/B6 were given to the leukemia-bearing mice at a dose of 100 microg weekly for 4 weeks. The three antibodies inhibited the leukemia growth significantly in SCID/NOD wild-type mice, as monitored by serum levels of human beta2-microglobulin (P < 0.01), and prolonged survival of the leukemia-bearing SCID/NOD wild-type mice (P < 0.01) as compared with the control group. However, none of the antibodies manifested efficacy on the leukemia growth and survival of the SCID/NOD FcRgamma-/- mice bearing MET-1 leukemia. In a pharmacokinetics study, the blood concentrations of the radiolabeled antibodies decreased with time similarly in SCID/NOD wild-type and SCID/NOD FcRgamma-/- mice. Although NK cells may play a role in humans, in this murine model FcRgamma receptors on non-NK cells, such as polymorphonuclear leukocytes or monocytes, are required for the tumor-killing action of the antibodies directed toward CD25.     

Experimental immunotherapy of colorectal carcinoma by monoclonal antibody ND4

The potential for experimental immunotherapy of colorectal cancers by mouse IgG2a monoclonal antibody (MAb) ND4 is investigated. The MAb ND4 recognizes a 160 kd cell surface glycoprotein that is strongly expressed in 58% of colorectal carcinomas. The antibody is internalizable by MIP-101 colorectal carcinoma cells. Biodistribution studies in nude mice bearing MIP-101 subcutaneous tumors showed accumulation of 125I-ND4 MAb in tumors from 5% at 18 hours to 14% of the injected dose per gram tissue at 14 days after intraperitoneal (i.p.) injection. Experimental immunotherapy studies using 125I-ND4 in MIP-101 tumor-bearing nude mice showed 64% inhibition of tumor growth 2 weeks after two i.p. injections at 7-day intervals. The MAb ND4 may be useful as a therapeutic reagent for colorectal tumors.     

Epidermal growth factor prolongs survival time of tumor-bearing mice

We observed that human epidermal growth factor (hEGF) alone prolonged the survival time of mice bearing various murine syngeneic tumors as well as athymic nude mice bearing human xenografts. No changes in the subcutaneous solid tumor mass volume were observed. Prolongation of survival time by hEGF was observed in mice bearing murine epidermoid carcinoma (BSC) and human gastric carcinoma (KATO III), but not in murine epidermoid carcinoma (KLN205) or human epidermoid carcinoma (A431). Human tumor cells such as A431, KATO III, and murine tumor cells, KLN205, BSC had roughly 2 X 10(6), 3 X 10(4), 1.3 X 10(3) and 1 X 10(3) EGF receptors/cell, respectively. Although KLN205 and BSC tumor cells maintained nearly the same number of EGF receptors, the effects of hEGF were very different. Although A431 tumor cells had nearly 100 times more receptors than KATO III cells, the prolongation of survival time of mice bearing A431 by hEGF was no better than that of mice bearing KATO III. Accordingly, it appears that this prolongation of survival time by hEGF is independent of the number of EGF receptors on tumor cells. In addition, hEGF was shown to inhibit experimental pulmonary metastasis of murine BSC tumor, but was ineffective with murine KLN205 tumor. These results suggest that prolongation of survival time by hEGF may result from the inhibition of tumor cell metastasis and EGF may play a role in preventing the metastasis of certain malignant neoplasms unrelated to its effects through the EGF receptor on tumor cells.     

Antibody-dependent cytotoxic activity on human cancer cells expressing UK 114 tumor membrane antigen

The monoclonal antibody (P-3 mAb) and the rabbit immune sera (RIS) recognizing a 14 kDa perchloric acid soluble protein extracted from goat liver (UK 114), locate this antigen on the cell membrane of several human cancer cell lines. UK 114-positive cells (e.g. HT 29 and KATO VI cells) undergo antibody-dependent cytolysis bl vitro. In nu/nu mice bearing xenografted HT 29 cells, tumor growth was markedly impaired by peri-tumoral injection of anti-UK 114 antibodies. These experiments suggest that human tumors expressing UK 114 over the cell membrane may undergo antibody-mediated cytolysis and growth control.     

Development of neoplastic phenotype following transfection of HNF cells with sarcoma DNA

DNA isolated from chondrosarcoma cells effectively transformedNIH-3T3 cells and human foreskin fibroblasts. The transfectedNIH-3T3 cells, directly implanted three or four passages later,formed progressively growing tumors ( 2.0 cm in diameter) subcutaneouslyin nude mice. No metastasis was evident upon pathological examinationof the tumor bearing mice. Transfected human foreskin fibroblaststhat exhibited anchorage independent growth formed only smalltumors in nude mice (<0.6 cm in diameter). The transfectedhuman cells which exhibited anchorage independent growth reactedwith the monoclonal antibody 345.134S, specific for an epitopeexpressed by human sarcoma cells. The transfected NIH-3T3 cellsdid not exhibit reactivity with the same monoclonal antibody.Southern blot analysis of the DNA prepared from the transfectedNIH-3T3 cells, that developed as a progressively growing tumorin a nude mouse, revealed the presence of human repetitive DNAsequences.