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.     

Paracrine signalling in colorectal liver metastases involving tumor cell-derived PDGF-C and hepatic stellate cell-derived PAK-2

In a nude mouse model of colorectal liver metastases, we have identified a paracrine tumor cell/host cell signalling pathway that is apparently required for successful tumor growth. Whereas recombinant platelet derived growth factor-C (PDGF-C) and supernatants from PDGF-C secreting wild type LS174T colon carcinoma cells could rescue tumor promoting hepatic stellate cells (HSC) from growth inhibition by serum starvation, supernatants from LS174T colon carcinoma cells with reduced secretion of PDGF-C had much less effect on serum starved HSC. Autocrine growth inhibition of LS174T cells by PDGF-C knock-down was only marginal. In vivo, a prominent inhibition of liver metastasis was observed if PDGF-C was knocked-down in LS174T cells. By whole genome array analysis of host cells of the invasion front and subsequent immunohistochemical staining we identified p21 activated kinase-2 (PAK-2) as being strongly and specifically expressed by HSC. The above described effect of PDGF-C on HSC was found to be dependent on PAK-2 because in contrast to wild type HSC, silencing of PAK-2 in HSC only allowed for a partial PDGF-C-mediated rescue from serum starvation leading to only a slight increase of proliferation. These data indicate that PDGF-C promotes tumor growth via a growth promoting effect on HSC that is at least in part dependent on the presence of functional PAK-2.     

不同人结直肠肿瘤细胞系对常用抗肿瘤药物体外化疗敏感性的比较

 目的：观察5种常用抗肿瘤药物对这些人结直肠肿瘤细胞系的生长抑制作用,探讨5种常用抗肿瘤药物对11株人结直肠肿瘤细胞系的作用强度以及比较其体外敏感性,研究不同抗肿瘤药物对人结直肠癌细胞系HCT116和SW480热休克蛋白27（HSP27）和HSP70表达水平的影响。方法：采用CCK-8（Cell Counting Kit-8）法检测5种常用抗肿瘤药物分别对11株人结直肠肿瘤细胞系的生长抑制效应,计算50%抑制浓度（50% inhibitory concentration, IC50）及敏感指数,并比较不同人结直肠肿瘤细胞系对5种抗肿瘤药物的敏感性,Western blotting检测HSP27和HSP70蛋白表达水平。结果：11株人结直肠肿瘤细胞系对5-氟尿嘧啶(5-FU)和奥沙利铂(OHP)均比较敏感,没有明显耐药性;5株人结直肠肿瘤细胞系对丝裂霉素(MMC)敏感,6株中度敏感;除SW1116 外的10株人结直肠肿瘤细胞系都对多西紫杉醇(DXL)敏感,而SW1116细胞对DXL表现出明显耐药性;除LS174T和SW1116外的9株人结直肠肿瘤细胞系都对伊立替康(IFL)表现出中度敏感,LS174T细胞对IFL表现敏感,而SW1116细胞对IFL表现出明显耐药性。抗肿瘤药物作用于人结直肠癌细胞系HCT116和SW480使HSP27的表达上调,但HSP70的表达水平变化不明显。结论：LS174T是多药敏感细胞株,SW1116是多药耐药细胞株,5-FU和OHP为广谱抗结直肠肿瘤药物;化疗药物的敏感性及HSP27表达量检测对临床选择化疗药物具有一定的提示意义。     

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.     

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。     

Treatment of established tumor is associated with ICAM-1 upregulation and reversed by CD8 depletion in a tumor necrosis factor-alpha gene transfected mouse mammary tumor.

INTRODUCTION: We have performed TNF-alpha gene transfection in a mouse mammary cancer line and found significant antitumor effects. We hypothesize that the antitumor effects observed in this model are mediated by ICAM-1 and by the recruitment of CD4+ and CD8+ T cells. In vivo (Balb/c mice) tumor growth inhibition, treatment of established tumor and the effects of ICAM-1 and CD4+ and CD8+ T cells were evaluated. METHODS AND RESULTS: Gene transfection with highly efficient vectors resulted in secretion of large amounts of TNF-alpha (ELISA). In vivo antitumor effects were tested. The number of cells required to generate palpable tumor 7-10 days after subcutaneous injection was determined (1 x 10(6)). The same number of transfected cells were injected subcutaneously and compared to nontransfected controls. Tumors were measured blindly and size was analyzed on day 30 by the Wilcoxon rank sum test. Mean tumor size after injection of transfected cells is compared to that of controls. Control tumors reached the maximum allowable size by day 30 (4 cm(2)). On day 30 EMT6-TNF-alpha tumors were 0.48 cm(2) (p < 0.05). The effect of repeat injection (challenge was also tested. Animals were injected with transfected cells or wild-type control on day -6 and challenged with the same number of wild-type tumor cells on day 0. Significant immune protection against subsequent challenge was seen after first time injection with EMT6-TNF-alpha but not after first time EMT6 wild-type injection (1.62 vs. 4 cm(2)). Treatment of 6-day-old tumor was also evaluated. On day 30, mean tumor size in animals treated with EMT6-TNF-alpha was 0.9 cm(2) compared to 4 cm(2) for controls. In all experiments, CD8+ T cell depletion and CD4+ T cell depletion caused a reversal of TNF-alpha-induced inhibitory effects. In addition, in vivo antibody blocking of ICAM-1 in tumor growth experiments reversed antitumor effects (control 4 cm(2), TNF-alpha 0.2 cm(2) and ICAM-1 blocking 3.14 cm(2)). Using flow cytometry, MHC class I and II and ICAM-1 adhesion molecule expression of transfected tumor was tested. ICAM-I expression was significantly upregulated. MHC class II antigen expression was also increased. TNF-alpha-transfected human breast cancer was also evaluated. Three cell lines and fresh tumor were transfected to express TNF-alpha. In vitro analysis revealed ICAM-1 upregulation following transfection. Histologic analysis and immunohistochemical staining revealed TNF-alpha and ICAM-1 in transfected tumors and not in wild-type tumors. CONCLUSION: Highly significant in vivo tumor growth inhibition and immune protection after injection with TNF-alpha-transfected tumors appears to be mediated predominantly by CD8+ T cells and ICAM-1 upregulation. These findings suggest that TNF-alpha increases recruitment and adhesion of effector T cells.     

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.     

A new approach for the immunogenic presentation of membrane-bound human colon tumor antigens

Liposomes bearing human tumor membrane vesicles were effective immunogenic complexes for inducing antibodies in rabbits. Multilamellar liposomes (MLV) at 7:4:1 molar ratios of phosphatidylcholine, cholesterol and phosphatidic acid were prepared with sonicated membrane (MN) isolated from LS174T colon tumor cells. MLV liposomes prepared together with MN (i.e., MN-MLV antigens) or MN added to preformed MLV (i.e., MN+MLV antigens), and MN antigens alone were used as immunogens. Rabbits were immunized i.v. with 100 g protein of each antigen group. Boosters (i.v.) were at days 13 and 29. Binding assays were performed by indirect radioimmunoassay on viable tumor cell targets. The MN+MLV groups were distinguished by earlier reactivity and greater specificity to the colon tumor antigens.     

A New Approach for the Immunogenic Presentation of Membrane-Bound Human Colon Tumor Antigens

Liposomes bearing human tumor membrane vesicles were effective immunogenic complexes for inducing antibodies in rabbits. Multilamellar liposomes (MLV) at 7:4:1 molar ratios of phosphatidylcholine, cholesterol and phosphatidic acid were prepared with sonicated membrane (MN) isolated from LS174T colon tumor cells. MLV liposomes prepared together with MN (i.e., MN-MLV antigens) or MN added to preformed MLV (i.e., MN+MLV antigens), and MN antigens alone were used as immunogens. Rabbits were immunized i.v. with 100 g protein of each antigen group. Boosters (i.v.) were at days 13 and 29. Binding assays were performed by indirect radioimmunoassay on viable tumor cell targets. The MN+MLV groups were distinguished by earlier reactivity and greater specificity to the colon tumor antigens.     

胸腺肽α1联合DC疫苗对结肠癌体内外抗肿瘤的效应

目的观察胸腺肽α1(Tα1)对结肠癌细胞裂解物(TuLy)负载DC(LyDC)的表型和功能的影响,以及二者联合应用对裸鼠结肠癌的治疗作用.方法从健康人外周血单个核细胞中常规诱导培养未成熟DC(imDC),并负载TuLy后制备LyDC疫苗.Tα1体外刺激imDC、LyDC,流式细胞术(FCM)检测DC表型变化;ELISA法检测LyDC与自体T细胞共培养时,Tα1对LyDC分泌IL-12以及活化T细胞分泌IFN-γ水平的影响;MTT法检测LyDC经Tα1刺激后所诱导的细胞毒活性的变化.对HT-29结肠癌裸鼠模型行人源化T细胞免疫重建,观察LyDC与Tα1联合应用时的体内抗肿瘤效果.结果Tα1刺激后的imDC、LyDC表型HLA-DR、CD80、CD86、CD83均上调(P＜0.01);Tα1刺激组上清液中细胞因子IL-12和IFN-γ的水平较未刺激组增加(P＜0.05,P＜0.01);LyDC经Tα1刺激后诱导的CTL细胞毒活性较未经Tα1刺激组增强(P＜0.01).结肠癌裸鼠模型体内的人源化细胞免疫重建成功,在接种HT-29细胞58 d后,LyDC Tα1组和LyDC组的抑瘤率分别为60.41%和37.20%,二组之间瘤体积及瘤质量比较具有统计学意义(P＜0.01).结论Tα1可促进DC分化成熟,并能增强LyDC诱导的CD4 Th1细胞反应和CTL的杀伤效应.Tα1与LyDC疫苗联合应用时具有较好的免疫佐剂活性和抗肿瘤作用.     

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.     

Injection of recombinant tumor necrosis factor directly into liver metastases: an experimental and clinical approach

Systemic treatment with tumor necrosis factor (TNF) is associated with side-effects, limiting its clinical use in the treatment of malignancies. To investigate the feasibility of other routes of administration experimental and clinical studies were started to establish the toxicity and antitumor activity of TNF after intratumoral (i.t.) injection. In a rat model for colon adenocarcinoma, tumor fragments, implanted subcutaneously or under the hepatic capsule, were treated with TNF injected i.v. or i.t. A dosage of 40 g/kg was lethal when given i.v., but not i.t. Injection of TNF (40 g/kg) directly into the tumor resulted in inhibition of tumor growth in the subcutaneous as well as subhepatic tumor model. A phase I study was started in patients with advanced malignancies to determine the toxicity of TNF injected into liver metastases. Injection of TNF into liver metastases was accomplished by ultrasonography. A 50 g-dose escalating schedule (3 patients/dosage) was chosen, starting at a dose of 100 g TNF/injection. Up to now, 12 patients have been treated, the highest dosage of TNF injected being 250 g. Chills, fever, nausea and vomiting were the main side-effects. No significant changes were found in circulatory, hematologic, renal and liver parameters. In summary, i.t. administration of TNF is associated with antitumor efficacy in experimental models and well-tolerated in man. The antitumor efficacy of TNF i.t. in man awaits evaluation in a phase II study.     

Mycobacterial sulfolipid shows a virulence by inhibiting cord factor induced granuloma formation and TNF-alpha release

Virulence mechanism of infection with Mycobacterium tuberculosis is currently focused to be clarified in the context of cell surface lipid molecule. Comparing two mycobacterial glycolipids, we observed toxicity and prominent granulomatogenic activity of trehalose 6,6'-dimycolate (TDM) injection in mice, evident by delayed body weight gain and histological observations, whereas 2,3,6,6'-tetraacyl trehalose 2'-sulfate (SL) was non-toxic and non-granulomatogenic. Likewise, TDM but not SL caused temporarily, but marked increase of lung indices, indicative of massive granuloma formation. Interestingly, co-administration of TDM and SL prevented these symptoms distinctively and SL inhibited TDM-induced release of tumor necrosis factor alpha (TNF-alpha) in a dose-dependent manner. Histological findings and organ index changes also showed marked inhibition of TDM induced granuloma formation by co-administration of SL. Simultaneous injection of SL together with TDM was highly effective for this protection, as neither injection 1h before nor after TDM injection showed highly inhibitory. In parallel studies on a cellular level, TDM elicited strong TNF-alpha release from alveolar but not from peritoneal macrophages in vitro. This effect was blocked when alveolar macrophages were incubated in wells simultaneously coated with TDM and SL, indicating that SL suppresses TDM-induced TNF-alpha release from macrophages. Our results suggest a novel mechanism by which SL could contribute to virulence at early stage of mycobacterial infection or stimulation with the glycolipids by counteracting the immunopotentiating effect of TDM.     

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。     

Antitumor effect of FP3 in combination with cetuximab on patient-derived tumor tissue xenograft models of primary colon carcinoma and related lymphatic and hepatic metastases

FP3 is an engineered protein which contains the extracellular domain 2 of vascular endothelial growth factor (VEGF) receptor 1 (Flt-1) and the extracellular domain 3 and 4 of VEGF receptor 2 (Flk-1, KDR) fused to the Fc portion of human immunoglobulin G1. Previous studies have demonstrated its antiangiogenic effects in vitro and in vivo, and its antitumor activity in vivo. Cetuximab is a monoclonal antibody against epidermal growth factor (EGF) receptor. Combined inhibition of VEGF and EGF signaling may act additively or synergistically. In this study, patient-derived tumor tissue (PDTT) xenograft models of primary colon carcinoma and lymphatic and hepatic metastases were established for assessment of the antitumor activity of FP3 in combination with cetuximab. Xenografts were treated with FP3 and cetuximab, alone or in combination. After tumor growth was confirmed, volume and microvessel density in tumors were evaluated. Levels of VEGF, EGFR and PCNA in the tumor were examined by immunohistochemical staining, and levels of related cell signaling pathway proteins were examined by western blotting. FP3 in combination with cetuximab showed significant antitumor activity in three xenograft models (primary colon carcinoma, lymphatic metastasis and hepatic metastasis). The microvessel density in tumor tissues treated with FP3 in combination with cetuximab was lower compared to that of the control. Antitumor activity of FP3 in combination with cetuximab was significantly higher than that of each agent alone in two xenograft models (colon carcinoma lymphatic metastasis and hepatic metastasis). This study indicated that addition of FP3 to cetuximab significantly improved tumor growth inhibition in the PDTT xenograft models of colon carcinoma lymphatic and hepatic metastases. Combination anti-VEGF (FP3) and anti-EGFR (cetuximab) therapies may represent a novel therapeutic strategy for the management of metastatic colon carcinoma.     

Antitumor activity and immune enhancement of murine interleukin-23 expressed in murine colon carcinoma cells

Interleukin （IL）-23, a cytokine composed of p19 and the p40 subunit of IL-12, can enhance the proliferation of memory T cells and production of IFN-γ from activated T cells. It can also induce antitumor effects in murine model. To further evaluate the antitumor activity and immune enhancement of IL-23 in vivo, murine colon carcinoma cells retrovirally transduced with mIL-23 gene were injected subcutaneously （s.c.） into BALB/c mice. Survival time and tumor volume were observed. LDH release assay, [^3H]-TdR incorporation assay and ELISA were used to determine CTL activity, proliferation of splenocytes and level of cytokines, respectively. Number of dendritic cells （DCs） was analyzed by flow cytometry （FCM）. IL-23 secreted by Colon26/IL-23 cells suppressed the growth of tumor and prolonged the survival time of mice, enhanced proliferation of splenocytes, CTL activity, and number of DCs. IL-23 also promoted the production of Thl cytokines such as IFN-γ, IL-12 and TNF-α. However, the level of IL-4 was not enhanced significantly. These data suggested that IL-23 secreted by tumor cells can induce antitumor activitv bv enhancing immune resnonse.     

Tumor antigen presentation by epidermal antigen-presenting cells in the mouse: modulation by granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha, and ultraviolet radiation.

I-A+ epidermal antigen-presenting cells (APCs, Langerhans cells) have been shown to present tumor-associated antigens (TAAs) and to induce tumor immunity in vivo. This study examined the effects of ultraviolet radiation (UVR) and the cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor alpha (TNF-alpha) on the ability of epidermal cells (ECs) to induce or to elicit immunity against the murine spindle cell tumor S1509a. Naive syngeneic mice were immunized three times at weekly intervals with ECs that had been cultured in GM-CSF for 18 h and then pulsed with TAA derived from S1509a. This resulted in protective immunity against subsequent tumor challenge, providing a model to study the conditions required for sensitization against TAAs by epidermal APCs. Culture of ECs in GM-CSF was required for induction of significant protective tumor immunity, and UV irradiation or incubation in TNF-alpha for 2 h after GM-CSF incubation abrogated the immunostimulatory effect of GM-CSF. However, unlike UVR, TNF-alpha did not significantly inhibit the induction of immunity when ECs were exposed to TNF-alpha before overnight incubation in GM-CSF, together with GM-CSF, or after pulsing with TAA, and anti-TNF-alpha antibody treatment did not abrogate the effects of UVR on this system. Furthermore, TNF-alpha incubation of ECs augmented their ability to elicit delayed-type hypersensitivity (DTH) and also enhanced elicitation of DTH by GM-CSF-cultured ECs, whereas UV-irradiation reduced it in a dose-dependent fashion. Taken together, these results demonstrate that GM-CSF, TNF-alpha, and UVR are significant regulators of tumor antigen presentation by epidermal APCs and that the effects of the cytokines examined differ with regard to induction or elicitation of immunity.     

Antitumor monoclonal antibodies generated by immunization with mucins.

This report describes the development and characterization of monoclonal antibody EG2.3. Although produced from a fusion that used splenocytes from donor mice immune to bovine salivary mucin (BSM), EG2.3 bound selectively to a number of human tumor cell lines including colon adenocarcinoma LS174T. Therefore, EG2.3 was compared to B72.3, another mucin (TAG-72) binding monoclonal antibody that also binds to LS174T. Like B72.3, EG2.3 reacted with an epitope on TAG-72. However, these two MAbs differed in a number of ways. Treatment of mucin or TAG-72 with periodate did not reduce the binding of EG2.3 to either antigen. In contrast, B72.3 did not react with either periodate treated antigens. Removal of sialic acid from either BSM or TAG-72 compromised the reactivity of both EG2.3 and B72.3. It was concluded that the EG2.3 binding site was distinct from the carbohydrate structure detected by B72.3.     

A pooled analysis of adjuvant chemotherapy for resected colon cancer in elderly patients

BACKGROUND: Adjuvant chemotherapy is standard treatment for patients with resected colon cancer who are at high risk for recurrence, but the efficacy and toxicity of such treatment in patients more than 70 years of age are controversial. METHODS: We performed a pooled analysis, based on the intention to treat, of individual patient data from seven phase 3 randomized trials (involving 3351 patients) in which the effects of postoperative fluorouracil plus leucovorin (five trials) or fluorouracil plus levamisole (two trials) were compared with the effects of surgery alone in patients with stage II or III colon cancer. The patients were grouped into four age categories of equal size, and analyses were repeated with 10-year age ranges (< or =50, 51 to 60, 61 to 70, and >70 years), with the same conclusions. The toxic effects measured in all trials were nausea or vomiting, diarrhea, stomatitis, and leukopenia. Patients in the fluorouracil-plus-leucovorin and fluorouracil-plus-levamisole groups were combined for the efficacy analysis but kept separate for toxicity analyses. RESULTS: Adjuvant treatment had a significant positive effect on both overall survival and time to tumor recurrence (P<0.001 for each, with hazard ratios of death and recurrence of 0.76 [95 percent confidence interval, 0.68 to 0.85] and 0.68 [95 percent confidence interval, 0.60 to 0.76], respectively). The five-year overall survival was 71 percent for those who received adjuvant therapy, as compared with 64 percent for those untreated. No significant interaction was observed between age and the efficacy of treatment. The incidence of toxic effects was not increased among the elderly (age >70 years), except for leukopenia in one study. CONCLUSIONS: Selected elderly patients with colon cancer can receive the same benefit from fluorouracil-based adjuvant therapy as their younger counterparts, without a significant increase in toxic effects.     

Interleukin (IL)-24 transforms the tumor microenvironment and induces anticancer immunity in a murine model of colon cancer

Interleukin-24 (IL-24) is a novel tumor suppressor and can mediate the induction of Th1-type cytokines from peripheral blood mononuclear cells. The individual properties of IL-24 have been previously examined; however, its in vivo immunological consequences and antitumor properties have not been previously evaluated with respect to colon cancer, the most commonly diagnosed cancer in China. Thus, we evaluated whether IL-24 could inhibit the progression of colon cancer in murine models with intact immune competence and explored the mechanisms underlying the immunological effects of IL-24 on colon cancer progression in vivo. In these murine models, we found that IL-24 promoted CD4⁺ T cells and CD8⁺ T cells to secrete interferon gamma and enhanced the cytotoxicity of CD8⁺ T cells in vivo. More importantly, we demonstrated that IL-24 transformed the tumor microenvironment and enhanced antitumor effects in favor of tumor eradication. Additionally, IL-24 expression correlated inversely with the clinical stage of human colorectal cancer. Thus, our study establishes a role of IL-24 in promoting antitumor immune responses and supports the development of a novel cytokine immunotherapy against colon cancer.