不同增殖能力结肠癌细胞株iNOSmRNA表达的比较研究

目的:探讨iNOSmRNA在结肠癌不同增殖能力细胞株中的表达和作用,研究ATRA对于结肠癌不同增殖能力细胞株iNOSmRNA表达的影响。方法:采用MTT方法确定结肠癌细胞株CW-2和LS174T的生长增殖状况,用RT-PCR和Northernblot方法检测结肠癌中iNOSmRNA的表达量。结果:MTT生长曲线显示结肠癌细胞株LS174T的生长增殖比CW-2快;RT-PCR显示CW-2细胞株有较强的iNOSmRNA表达,而LS174T细胞株iNOSmRNA的表达较弱;Northernblot检测在CW-2中有明显的iNOSmRNA表达,但在细胞株LS174T中表达相对较弱;ATRA对结肠癌CW-2和LS174T细胞株iNOSmRNA的表达量无明显影响。结论:iNOSmRNA对结肠癌细胞株生长有双重作用,即在低增殖结肠癌CW-2呈高表达,可以通过细胞毒或诱导细胞凋亡等作用发挥抗肿瘤效应;在高增殖结肠癌LS174T呈低表达,产生NO作为信号转导的重要分子,增加血供和血管生成,促进肿瘤生长、侵袭和转移。ATRA可以抑制结肠癌细胞株的生长。     

Netrin-4 delays colorectal cancer carcinomatosis by inhibiting tumor angiogenesis

A close relationship between tumor angiogenesis, growth, and carcinomatosis has been observed. Netrin-4 (NT-4) has been shown to regulate angiogenic responses. We aimed to examine the effects of NT-4 on colon tumor angiogenesis, growth, and carcinomatosis. We showed that NT-4 was expressed in human colon cancer cells (LS174). A 20-fold increase in NT-4 expression was stably induced by NT-4 pcDNA in LS174 cells. In vivo, a Matrigel angiogenesis assay showed that NT-4 overexpression altered vascular endothelial growth factor (VEGF)/basic fibroblast growth factor-induced angiogenesis. In nude mice with LS174 xenografts, NT-4 overexpression inhibited tumor angiogenesis and growth. In addition, these NT-4-involved inhibitory effects were associated with decreased tumor cell proliferation and increased tumor cell apoptosis. Using an orthotopic peritoneal carcinomatosis model, we demonstrated that NT-4 overexpression decreased colorectal cancer carcinomatosis. Moreover, carcinomatosis-related ascites formation was significantly decreased in mice transplanted with NT-4 LS174 cells versus control LS174 cells. The antiangiogenic activity of NT-4 was probably mediated by binding to its receptor neogenin. Netrin-4 had a direct effect on neither in vitro apoptosis and proliferation of cultured LS174 cells nor the VEGF-induced acute increase in vascular permeability in vivo. We propose that NT-4 overexpression decreases tumor growth and carcinomatosis, probably via an antiangiogenic effect, underlying the potential therapeutic interest in NT-4 in the treatment of colorectal cancer growth and carcinomatosis.     

全反式维甲酸对结肠癌不同增殖潜能细胞株VEGF表达的影响

目的:探讨全反式维甲酸对结肠癌不同增殖潜能细胞株VEGF表达的作用；研究VEGF在结肠癌侵袭和转移中的作用。 方法:采用细胞培养观察、ATRA干预、MTT和FACS方法确定结肠癌细胞株CW-2和LS174T的生长增殖状况，用Northern blotting方法检测结肠癌中VEGF mRNA的表达量，用免疫细胞化学观察细胞VEGF蛋白的表达。 结果:MTT生长曲线显示结肠癌细胞株LS174T的生长增殖比CW-2快;FACS结果显示LS174T细胞的S期细胞较CW-2细胞数多；Northern blotting和免疫细胞化学检测在CW-2中有明显的VEGF表达，但在高增殖细胞株LS174T中VEGF的表达更明显。 结论:VEGF在结肠癌细胞株中有较高的表达。在高增殖结肠癌细胞株VEGF表达更明显。ATRA可能通过抑制VEGF表达，而抑制结肠癌细胞的增生。     

Role of nitric oxide in tumor microcirculation. Blood flow, vascular permeability, and leukocyte-endothelial interactions.

The present study was designed to define the role of nitric oxide (NO) in tumor microcirculation, through the direct intravital microcirculatory observations after administration of NO synthase (NOS) inhibitor and NO donor both regionally and systemically. More specifically, we tested the following hypotheses: 1) endogenous NO derived from tumor vascular endothelium and/or tumor cells increases and/or maintains tumor blood flow, decreases leukocyte-endothelial interactions, and increases vascular permeability, 2) exogenous NO can increase tumor blood flow via vessel dilatation and decrease leukocyte-endothelial interactions, and 3) NO production and tissue responses to NO are tumor dependent. To this end, a murine mammary adenocarcinoma (MCaIV) and a human colon adenocarcinoma (LS174T) were implanted in the dorsal skinfold chamber in C3H and severe combined immunodeficient mice, respectively, and observed by means of intravital fluorescence microscopy. Both regional and systemic inhibition of endogenous NO by N omega-nitro-L-arginine methyl ester (L-NAME; 100 mumol/L superfusion or 10 mg/kg intravenously) significantly decreased vessel diameter and local blood flow rate. The diameter change was dominant on the arteriolar side. Superfusion of NO donor (spermine NO, 100 mumol/L) increased tumor vessel diameter and flow rate, whereas systemic injection of spermine NO (2.62 mg/kg) had no significant effect on these parameters. Rolling and stable adhesion of leukocytes were significantly increased by intravenous injection of L-NAME. In untreated animals, both MCaIV and LS174T tumor vessels were leaky to albumin. Systemic NO inhibition significantly attenuated tumor vascular permeability of MCaIV but not of LS174T tumor. Immunohistochemical studies, using polyclonal antibodies to endothelial NOS and inducible NOS, revealed a diffuse pattern of positive labeling in both MCaIV and LS174T tumors. Nitrite and nitrate levels in tumor interstitial fluid of MCaIV but not of LS174T were significantly higher than that in normal subcutaneous interstitial fluid. These results support our hypotheses regarding the microcirculatory response to NO in tumors. Modulation of NO level in tumors is a potential strategy for altering tumor hemodynamics and thus improving oxygen, drug, gene vector, and effector cell delivery to solid tumors.     

Malignant and other properties of human colon carcinoma cells after suppression of sulfomucin production in vitro

Although the loss of sulfomucins was known as an indicator of carcinogenesis and malignant progression of colonic epithelia, it was not known whether the loss was directly related to the malignant behavior of colon carcinoma cells. We have studied the biological properties of LS174T human colon carcinoma cells before and after suppression of sulfomucin production. Incorporation of [³⁵S]-sulfate into high molecular weight mucins decreased after carcinoma cell treatment with 1.5% dimethylsulfoxide (DMSO) for 8 days. The amounts of sulfomucin determined using a sulfomucin-specific monoclonal antibody (mAb 91.9H), in Western blot and flowcytometric analyses, also decreased. In addition, the levels of MUC2 and MUC5B mucin gene expression measured by RT-PCR were reduced after DMSO-treatment, whereas the levels of MUC1, MUC5AC, and MUC6 mucin gene expression were not. The DMSO-treated cells were tested in vitro and in vivo for their properties. Differences were not detected in their anchorage-independent growth, anchorage-dependent growth, E-selectin-dependent cell adhesion or sensitivity to interleukin (IL)-2-activated lymphocyte cytolysis. When untreated or DMSO-treated LS174T cells were injected intrasplenically into nude mice, the treated cells lacking certain cell surface sulfomucins formed fewer metastatic colonies in the liver. These results suggest that the loss of sulfomucins by colonic epithelial cells during progression is not directly related to the enhanced malignant behavior.     

Effect of host microenvironment on the microcirculation of human colon adenocarcinoma.

It is generally accepted that the host microenvironment influences tumor biology. There are discrepancies in growth rate, metastatic potential, and efficacy of systemic treatment between ectopic and orthotopic tumors. Liver is the most common and critical site of distant metastasis of colorectal carcinoma. Tumorigenicity and efficacy of chemotherapeutic agents in colorectal tumors are different in liver and subcutaneous sites. Thus, we hypothesize that the liver (orthotopic) versus subcutaneous (ectopic) microenvironment would have different effects on the angiogenesis and maintenance of the microcirculation of colorectal tumor. To this end, we developed a new method to monitor and to quantify microcirculatory parameters in the tumor grown in the liver. Using this approach, we compared the microcirculation of LS174T, a human colon adenocarcinoma, metastasized to the liver with that of the host liver vessels and that of the same tumor grown in the subcutaneous space. In the liver metastasis model, 5 x 10(6) LS174T cells were injected into the spleen of nude mice. Four to eight weeks later, the liver with metastatic tumors was exteriorized and placed on a special stage and observed under an intravital fluorescence microscope. The dorsal skinfold chamber model was used to study the subcutaneous tumors. Red blood cell velocity, vessel diameter, density, permeability, and leukocyte-endothelial interactions were measured using fluorescence microscopy and image analysis. Vascular endothelial growth factor/ vascular permeability factor (VEGF/VPF) mRNA expression was determined by the Northern blot analysis. LS174T tumor foci in the liver had tortuous vascular architecture, heterogeneous blood flow, significantly lower vascular density, and significantly higher vascular permeability than normal liver tissue. Tumors grown in the liver had significantly lower vessel density, especially in the center coincident with central necrosis, than the subcutaneous tumors. The frequency distribution of vessel diameters of liver tumor was slightly shifted to smaller size compared with that of subcutaneous tumor. Leukocyte rolling in liver tumor was twofold lower than that in subcutaneous tumor. These physiological findings were consistent with the measurement of VEGF/VPF in that the VEGF/VPF mRNA level was lower in the liver tumor than that in the subcutaneous tumor. However, macromolecular vascular permeability in the liver tumor was significantly higher than in the subcutaneous tumor. Liver sinusoidal endothelial cells, the origin of liver tumor vessel endothelium, are known to be fenestrated and not to have a basement membrane, suggesting that the difference in endothelial cell origin may explain the difference in tumor vascular permeability in two sites. These findings demonstrate that liver microenvironment has different effects on some aspects of the tumor angiogenesis and microcirculation compared with the subcutaneous tissues. The new model/method described in this paper has significant implications in two research areas: 1) the liver microenvironment and its effect on tumor pathophysiology in conjunction with cytokine/ growth factor regulation and 2) the delivery of drugs, cells, and genes to liver tumors.     

非甾体类抗炎药对结肠癌细胞NAG-1 基因表达的诱导

研究非甾体类抗炎药(Non-steroidal anti-inflammatory drug,NSAID)对结肠癌细胞生长的影响及NSAID活化基因-1(NAG-1)的诱导作用。体外培养HT-29、SW480及LS174-T三种结肠癌细胞,分别加入不同浓度的aspirin、celecoxib及meloxicam作用于HT-29及SW480细胞,采用MTT法检测结肠癌细胞增殖;蛋白质印迹技术检测三种结肠癌细胞COX-2的表达;采用半定量RT-PCR技术分析NSAID对三种结肠癌细胞NAG-1基因表达的影响。aspirin、celecoxib及meloxicam均能有效抑制体外培养的HT-29、SW480结肠癌细胞生长,并具有良好的量-效关系。Western blot表明,HT-29细胞表达COX-2,而SW480细胞不表达COX-2。三种结肠癌细胞均表达NAG-1基因mRNA,其中LS174-T细胞NAG-1基础水平较低;NSAID能不同程度上调结肠癌细胞NAG-1基因表达。NSAID能有效抑制结肠癌细胞生长,这种作用可能部分通过诱导结肠癌细胞NAG-1基因表达实现,NAG-1基因表达不受肿瘤细胞是否表达COX-2的影响。     

Stromal extracellular matrix reduces chemotherapy-induced apoptosis in colon cancer cell lines

Several studies have shown that extracellular matrix reduces chemotherapeutic drugs-induced apoptosis in small cell lung cancer cells, myelomas and gliomas. We have investigated the protective effect of defined extracellular matrix components and of extracellular matrix from different cell types (fibroblasts, hepatocytes and intestinal epithelial cells) on the toxicity of three types of chemotherapeutic drugs on colon cancer cells. Human colon cancer cell lines LS174T and LiM6 were plated on plastic, on hepatocyte-derived ECM or on stromal ECM and in the presence of the antimetabolite 5-fluorouracil (5-FU), the topoisomerase I inhibitor camptothecin and the topoisomerase II inhibitor etoposide. We determined IC50 for the drugs for each of these culture conditions. We also determined the expression of the anti-apoptotic proteins bcl-2 and bcl-x (L) under these culture conditions. We found that stromal ECM protected LiM6 cells from the toxicity of etoposide and LS174T, but not LiM6 cells, from the toxicity of camptothecin. Collagen I, fibronectin and fibroblast-derived ECM rendered LiM6 cells, but not LS174T, more sensitive to the harmful effect of 5-FU. Both colon cell lines had increased expression of anti-apoptotic proteins bcl-2 and bcl-x(L) when cultured on the various ECMs and with the drugs, but there was no correlation between a protective ECM effect and expression of the anti-apoptotic proteins. Stromal-derived ECM may protect colon cancer cells from etoposide and camptothecin-induced apotosis, through a mechanism that is not bcl-2 or bcl-x(L) dependant.     

Liposome-encapsulated tumor necrosis factor-alpha enhances the effects of radiation against human colon tumor xenografts.

Recent reports have shown that tumor necrosis factor-alpha (TNF-alpha) can augment the effects of radiation against certain tumor types. However, the high concentrations of intravenous infusion of TNF-alpha needed to cause tumor regression can induce many systemic side effects. The aims of this study were to determine if TNF-alpha encapsulated in sterically stabilized (Stealth, ALZA Corporation, Mountain View, CA), PEGylated liposomes (SL) augments the antitumor effects of radiation and to compare its efficacy and possible toxicity with free TNF-alpha in the LS174T human colon tumor xenograft model. Nude mice were injected subcutaneously (s.c.) with LS174T cells and treated intravenously (i.v.) with Stealth-liposomal TNF-alpha (SL-TNF-alpha) with and without radiation or TNF-alpha with or without radiation when tumor size was approximately 200 mm(3). In phase 1, a significant decrease (p = 0.047) in tumor growth was observed with radiation at day 21 but not with SL-TNF-alpha or free TNF-alpha alone. By the end of phase 1 (day 27) with continued treatments, the SL-TNF-alpha plus radiation group had significantly smaller tumors (p = 0.044) than those in the free TNF-alpha plus radiation group. In phase 2, where a similar tumor growth reduction pattern was observed, the addition of TNF-alpha to radiation, either as free protein or within SL, increased lymphocyte activation and natural killer (NK) cell numbers in both blood and spleen. The effect was generally more pronounced with SL-TNF-alpha. Systemic toxicity, based on hematologic analyses and body weight, was absent or minimal. Collectively, the data show that pretreatment with SL-TNF-alpha can enhance more effectively, and possibly more safely, the effects of radiation against human colon tumor xenografts than can free TNF-alpha and that the increased antitumor action may involve upregulation of lymphocytes.     

α-Difluoromethylornithine inhibits liver metastasis produced by intrasplenic injection of human tumor cells into nude mice

The purpose of these studies was to examine metastatic potentials of a human colon tumor xenograft (T6) and three different human tumor cell lines (LS174T, HT29 and A549) using the intrasplenic-nude mouse model system (ISMS model system). A further objective was to study the activity of-difluoromethylornithine (DFMO) against primary and metastatic growth of the xenograft and the three cell lines. DFMO is an irreversible inhibitor of ornithine decarboxylase, a rate-limiting step in polyamine biosynthesis. Tumor burdens in the liver of nude mice were observed 6 weeks after the intrasplenic injection with LS174T and 12–14 weeks after intrasplenic injections with T6, HT29 and A549. Most of the mice developed primary tumor growth in the spleens. DFMO showed significant activity against liver metastases but had little or no activity against primary tumor growth in the spleens of the ISMS model and against s.c. growth of the xenograft. The studies demonstrated that the ISMS model system is an excellent system for studying metastatic behavior of human tumors and for studying the antimetastatic activity of experimental drugs.     

Interaction of tumor cells with vascular endothelia: Role of platelet-activating factor

We investigated whether tumor cell/endothelia interaction can be influenced by platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine), a lipid mediator that promotes adhesiveness and extravasation of leukocytes in the inflammatory reaction. We found that the PAF receptor antagonist WEB 2086 prevents adhesion of melanoma Hs294T and colon carcinoma LS180 lines to IL-1-stimulated endothelial cells. Moreover, PAF stimulated the adhesiveness of Hs294T and LS180 cells to VCAM-1 and E- selectin, respectively, in an artificial model consisting of recombinant adhesive proteins bound to protein A-coated substrata. Thus, tumoral and not endothelial cell surface seems to be involved in the PAF-mediated enhancement of tumor cell adhesiveness to IL-1-activated endothelia. This observation is supported by the finding that Hs294T and LS180 cells express high affinity and functionally active receptors for PAF. By using specific inhibitors, we found that PAF-induced enhancement of cell adhesiveness was mediated by G-protein activation and protein tyrosine phosphorylation. In addition, protein tyrosine phosphorylation was observed in Hs294T and LS180 cells stimulated by PAF. In conclusion, we demonstrated that PAF-mediated activation of tumor cells enhances their adhesiveness to IL-1-stimulated vascular endothelia.     

Mesenchymal progenitor cell-mediated inhibition of tumor growth in vivo and in vitro in gelatin matrix

A preformed gelatin matrix containing adherent rat colon carcinoma cells was transplanted subcutaneously into rats to analyze the outgrowth of the tumor and the inflammatory response. The gelatin matrix simplifies the precise localization of the tumor cells early after implantation and allows the gelatin piece with a growing tumor to be dissected for analysis in vitro, after various times in vivo. The immortalized mesenchymal progenitor cell line MPC1cE was cocultured with rat colon carcinoma cells in vivo in gelatin matrix. The mesenchymal progenitor cells inhibited the outgrowth of the rat colon carcinoma and a complete inhibition was seen if the number of mesenchymal progenitor cells were at least equal to the number of tumor cells. The mixture of tumor cells and mesenchymal progenitor cells induced more infiltration of monocytes and granulocytes than tumor cells or mesenchymal progenitor cells alone. Infiltration of T cells and CD31+ endothelial cells correlated to the presence of tumor cells and not to mesenchymal progenitor cells. These findings suggest that tumor cell culture in vivo in a gelatin matrix is effective for early localization of tumor cells in vivo and that mesenchymal progenitor cells effectively inhibit the growth of the tumor cells in vivo.     

Kinetics of tumor cell apoptosis and immune cell activation during the regression of tumors induced by lipid A in a rat model of colon cancer

Despite the wide range of available therapies, human colon cancers remain difficult to cure. Evidence for efficient antitumoral immune responses to be raised is now widely accepted, and numerous strategies exploiting the host immune system have been developed. A treatment based on the lipid-A derivative OM-174 has been developed in our laboratory. OM-174 induces the rejection of tumors established by injection of PROb colon cancer cells in syngeneic BDIX rats. Our immunohistochemistry study demonstrated that OM-174 treatment is associated with tumor cell apoptosis. Caspase 3 activation was detected 24 h after the first OM-174 injection. Six days after the beginning of the treatment, dendritic cells were the first immune cells that invaded tumor nodules. When dendritic cells came into contact with apoptotic tumor cells, an increased expression of the costimulatory molecules B7-1 and B7-2 was detected at the surface of these cells. Five days later, macrophages were found in the tumor nodules. Lymphocytes organized into a crown surrounding the nodules that progressively regressed during the treatment. T lymphocytes were not in contact with tumor cells or apoptotic cells at any time point. The kinetics of tumor cell apoptosis induced by OM-174, as well as the appearance of innate followed by adaptative immune cells in the tumor nodules, were compatible with cell activation and the development of immune response.     

EGFR单克隆抗体抗结肠癌作用的实验研究

目的:观察表皮生长因子受体单克隆抗体(EGFRMcAb)对结肠癌的作用。方法:用不同剂量的EGFRMcAb处理LST174结肠癌细胞系, 采用细胞计数、生长曲线测定及MTT法测定体外培养细胞的生长和增殖抑制率。结果:可见一定程度的增殖抑制并呈剂量依赖性。抗-EGFR抗体组细胞数明显低于对照组(P<0.01).不同浓度之间比较:当EGFRMcAb为0.625mL/L时细胞计数相对高, 是对照组的61.3%;当EGFRMcAb为2.5mL/L时细胞计数最低, 是对照组的33.8%.EGFRMcAb组细胞生长受到抑制, 细胞生长曲线较对照组速度减慢。MTT值显示实验组细胞增殖能力低于对照组, 抑制率为42.3%(P<0.01).结论:EGFRMcAb可抑制人结肠癌LST174细胞生长, 具有一定的抗结肠癌作用。     

Preparation and in vitro evaluation of 111In-CHX-A"-DTPA-labeled anti-VEGF monoclonal antibody bevacizumab

Bevacizumab is a humanized monoclonal antibody that binds to vascular endothelial growth factor (VEGF) and prevents tumor angiogenesis. Radionuclide imaging using radiolabeled bevacizumab might be useful for selection of patients for anti-VEGF therapy. This study describes preparation of a potential imaging agent, 111In-CHX-A"-DTPA-bevacizumab, and evaluation of specificity of its binding to three tumor cell lines, SKOV3, LS174T and DU 145. Bevacizumab was conjugated with CHX-A"-DTPA and radiolabeled with 111In with high yield and excellent stability. Specificity of cellular binding was examined by a saturation assay using 100-fold excess of non-radiolabeled antibody. SKOV3 and LS174T tumor cell lines showed significantly specific binding, while DU 145 cells did not showed any specific binding. The specific binding is dependent to type of cell lines, which it is important for selection of tumor model for scintigraphic imaging of the VEGF expression.     

Rate of incorporation of radiolabelled nucleosides does not necessarily reflect the metabolic state of cells in culture: effects of latent mycoplasma contamination.

In response to cell-free conditioned medium derived from the human bladder carcinoma line T24 (T24 SN), we found greatly reduced incorporation of tritiated thymidine and uridine ([3H]TdR, [3H]UR) by the human carcinoma lines UCHNCu (small-cell lung carcinoma) and LS174T (colon carcinoma). The effect was not due to an excess of nucleosides or cytokines known to be present in T24 SN. Cell-cycle distribution, increase in cell numbers, and de novo nucleoside synthesis in the indicator cells were only slightly altered. This was in contrast to the gross reduction in [3H]TdR/[3H]UR incorporation and seemed to indicate selective downregulation of pyrimidine-salvage pathways, despite ongoing polynucleotide synthesis. Spontaneous [3H]TdR uptake remained low for several passages in vitro but was readily restored by pharmacological inhibition of de novo pathways with 5-fluoro-deoxy-uridine (5-FUdR). This suggested a stable but reversible regulatory effect of T24 SN on the pyrimidine metabolism of the indicator cells. Further investigation showed degradation of [3H]TdR by a particle-bound activity in T24 SN. Mycoplasma contamination of T24 had not been detectable using standard cultural and staining methods, but became apparent when T24-cell lysates were hybridized with a recently described DNA probe (Goebel & Stanbridge, 1984). We conclude that latent mycoplasma contamination can stimulate changes in cellular pyrimidine metabolism. Our results provide an example for latent mycoplasma infection mimicking metabolic changes in cultured cells by direct interference of a microbial enzyme with the assay system. We describe a rapid and simple bioassay to detect and distinguish particle-associated and soluble phosphorylase activity by [3H]TdR degradation. It may be a useful screening assay for mycoplasma contamination in tissue culture.     

脂质体介导的cripto反义寡核苷酸抑制结肠癌细胞端粒酶活性

目的：探讨cripto反义寡核苷酸（ASODN）对结肠癌细胞端粒酶活性的影响。 方法: 应用脂质体瞬时转染法介导cripto 反义寡核苷酸，处理人结肠癌细胞系后，分别采用实时定量PCR检测cripto mRNA表达，用TRAP检测端粒酶活性，采用软琼脂集落培养试验检测结肠癌细胞的生长。 结果: Cripto ASODN可有效抑制结肠癌细胞集落生长，且与浓度相关。结肠癌细胞经Cripto ASODN转染后，端粒酶活性明显受到抑制，呈作用浓度和时间依赖性。并与ASODN的浓度和处理时间有关。 结论: cripto基因可能参与对结肠癌细胞端粒酶活性的调控。     

Inhibition of colon carcinoma cell lung colony formation by a soluble form of E-selectin.

During metastasis, tumor cells adhere to vascular endothelia. E-selectin is an adhesive protein expressed by cytokine-activated endothelium that can support adhesion of colon cancer cells through the recognition of specific carbohydrate ligands. Using a series of colon carcinoma cell lines that displayed E-selectin adhesiveness and an increased metastatic capacity in cytokine-treated mice, we examined possible inhibition of cytokine-dependent experimental lung metastasis by a soluble form of E-selectin, the recombinant fusion protein E-selectin-immunoglobulin. We found that E-selectin-immunoglobulin bound to the surfaces of HT-29 colon carcinoma cells and blocked the formation of cytokine-inducible experimental lung metastases; control L-selectin-immunoglobulin also bound to HT-29 cells but had no effect on tumor cell lung colonization. E-selectin-immunoglobulin was found to interfere with E-selectin-dependent adhesion of HT-29 cells to activated vascular endothelium and to block the retention of these cells in the lung, a process that implies tumor cell adhesive interactions with the host vasculature. Our results demonstrate that E-selectin-immunoglobulin inhibits adhesion and formation of lung metastases by colon carcinoma cells and suggest that impairment of tumor cell-endothelium adhesion might represent a therapeutic approach to the metastatic diffusion of tumors.