Environmental Enrichment Mitigates Age-Related Metabolic Decline and Lewis Lung Carcinoma Growth in Aged Female Mice

Aging is a complex physiological process that leads to the progressive decline of metabolic and immune function, among other biological mechanisms. As global life expectancy increases, it is important to understand determinants of healthy aging-including environmental and genetic factors-and thus slow the onset or progression of age-related disease. Environmental enrichment (EE) is a housing environment wherein laboratory animals engage with complex physical and social stimulation. EE is a prime model to understand environmental influences on aging dynamics, as it confers an antiobesity and anticancer phenotype that has been implicated in healthy aging and health span extension. Although EE is frequently used to study malignancies in young mice, fewer studies characterize EE-cancer outcomes in older mice. Here, we used young (3-month-old) and aged (14-month-old) female C57BL/6 mice to determine whether EE would be able to mitigate age-related deficiencies in metabolic function and thus alter Lewis lung carcinoma (LLC) growth. Overall, EE improved metabolic function, resulting in reduced fat mass, increased lean mass, and improved glycemic processing; many of these effects were stronger in the aged cohort than in the young cohort, indicating an age-driven effect on metabolic responses. In the aged-EE cohort, subcutaneously implanted LLC tumor growth was inhibited and tumors exhibited alterations in various markers of apoptosis, proliferation, angiogenesis, inflammation, and malignancy. These results validate EE as an anticancer model in aged mice and underscore the importance of understanding environmental influences on cancer malignancy in aged populations. PREVENTION RELEVANCE: Environmental enrichment (EE) serves as a model of complex physical and social stimulation. This study validates EE as an anticancer intervention paradigm in aged mice and underscores the importance of understanding environmental influences on cancer malignancy in aged populations.

Phloroglucinol inhibits the bioactivities of endothelial progenitor cells and suppresses tumor angiogenesis in LLC-tumor-bearing mice

BACKGROUND

There is increasing evidence that phloroglucinol, a compound from Ecklonia cava, induces the apoptosis of cancer cells, eventually suppressing tumor angiogenesis.

METHODOLOGY/PRINCIPAL FINDINGS

This is the first report on phloroglucinol's ability to potentially inhibit the functional bioactivities of endothelial progenitor cells (EPCs) and thereby attenuate tumor growth and angiogenesis in the Lewis lung carcinoma (LLC)-tumor-bearing mouse model. Although Phloroglucinol did not affect their cell toxicity, it specifically inhibited vascular endothelial growth factor (VEGF) dependent migration and capillary-like tube formation of EPCs. Our matrigel plug assay clearly indicated that orally injected phloroglucinol effectively disrupts VEGF-induced neovessel formation. Moreover, we demonstrated that when phloroglucinol is orally administered, it significantly inhibits tumor growth and angiogenesis as well as CD45(-)/CD34(+) progenitor mobilization into peripheral blood in vivo in the LLC-tumor-bearing mouse model.

CONCLUSIONS/SIGNIFICANCE

These results suggest a novel role for Phloroglucinol: Phloroglucinol might be a modulator of circulating EPC bioactivities, eventually suppressing tumorigenesis. Therefore, phloroglucinol might be a candidate compound for biosafe drugs that target tumor angiogenesis.

A novel vaccine delivery system: biodegradable nanoparticles in thermosensitive hydrogel

In this work, a novel vaccine delivery system, biodegradable nanoparticles (NPs) in thermosensitive hydrogel, was investigated. Human basic fibroblast growth factor (bFGF)-loaded NPs (bFGF-NPs) were prepared, and then bFGF-NPs were incorporated into thermosensitive hydrogel to form bFGF-NPs in a hydrogel composite (bFGF-NPs/hydrogel). bFGF-NPs/hydrogel was an injectable sol at ambient temperature, but was converted into a non-flowing gel at body temperature. The in vitro release profile showed that bFGF could be released from bFGF-NPs or bFGF-NPs/hydrogel at an extended period, but the release rate of bFGF-NPs/hydrogel was much lower. In vivo experiments suggested that immunogenicity of bFGF improved significantly after being incorporated into the NPs/hydrogel composite, and strong humoral immunity was maintained for longer than 12 weeks. Furthermore, an in vivo protective anti-tumor immunity assay indicated that immunization with bFGF-NPs/hydrogel could induce significant suppression of the growth and metastases of tumors. Thus, the NPs/hydrogel composite may have great potential application as a novel vaccine delivery system.

Chemokine-containing exosomes are released from heat-stressed tumor cells via lipid raft-dependent pathway and act as efficient tumor vaccine

Exosomes derived from dendritic cells or tumor cells are a population of nanometer-sized membrane vesicles that can induce specific antitumor immunity. During investigation of the effects of hyperthermia on antitumor immune response, we found that exosomes derived from heat-stressed tumor cells (HS-TEX) could chemoattract and activate dendritic cells (DC) and T cells more potently than that by conventional tumor-derived exosomes. We show that HS-TEX contain chemokines, such as CCL2, CCL3, CCL4, CCL5, and CCL20, and the chemokine-containing HS-TEX are functionally competent in chemoattracting CD11c(+) DC and CD4(+)/CD8(+) T cells both in vitro and in vivo. Moreover, the production of chemokine-containing HS-TEX could be inhibited by ATP inhibitor, calcium chelator, and cholesterol scavenger, indicating that the mobilization of chemokines into exosomes was ATP- and calcium-dependent and via a lipid raft-dependent pathway. We consistently found that the intracellular chemokines could be enriched in lipid rafts after heat stress. Accordingly, intratumoral injection of HS-TEX could induce specific antitumor immune response more efficiently than that by tumor-derived exosomes, thus inhibiting tumor growth and prolonging survival of tumor-bearing mice more significantly. Therefore, our results demonstrate that exosomes derived from HS-TEX represent a kind of efficient tumor vaccine and can chemoattract and activate DC and T cells, inducing more potent antitumor immune response. Release of chemokines through exosomes via lipid raft-dependent pathway may be a new method of chemokine exocytosis.

[Potential of prevention of metastasizing with the aid of tumor-specific transfer-factor]

The report discusses our experimental data in support of biotherapy which uses chemotherapy and antitumor immune treatment with in vivo xenogenic transfer-factor polypeptides (TFP) isolated from lymphocytes sensitized to antigens of given tumor. After excision of primary tumor--lung carcinoma of Lewis--mice C57BL/6 were injected intraperitoneally with xenogenic TFP (200 pg/body, twice) and a cytostaic dose of cyclophosphamide. Such adjuvant chemotherapy was found to prevent metastases from spreading to the lung in 100%. The marked anti-metastatic effect of the treatment correlated with recovery of splenic cell mass and its cellular structure, higher levels of large granular lymphocytes in peripheral blood and enhanced functional activity of cytotoxic cells in vitro. Our results point to a possibility of raising efficacy of treating solid malignancies with adjuvant chemotherapy in combination with adoptive immune therapy.

Integrating individual functional moieties of CXCL10 and CXCL11 into a novel chimeric chemokine leads to synergistic antitumor effects: a strategy for chemokine-based multi-target-directed cancer therapy

The complexity of tumor biology necessitates a multimodality approach that targets different aspects of tumor environment in order to generate the greatest benefit. IFN-inducible T cell alpha chemoattractant (ITAC)/CXCL11 and IFN-inducible protein 10 (IP10)/CXCL10 could exert antitumor effects with functional specificity and thus emerge as attractive candidates for combinatorial strategy. Disappointedly, a synergistic antitumor effect could not be observed when CXCL10 and CXCL11 were pooled together. In this regard, we seek to improve antitumor efficacy by integrating their individual functional moieties into a chemokine chimeric molecule, designated ITIP, which was engineered by substituting the N-terminal and N-loop region of CXCL10 with those of CXCL11. The functional properties of ITIP were determined by chemotaxis and angiogenesis assays. The antitumor efficacy was tested in murine CT26 colon carcinoma, 4T1 mammary carcinoma and 3LL lung carcinoma. Here we showed that ITIP not only exhibited respective functional superiority but strikingly promoted regression of established tumors and remarkably prolonged survival of mice compared with its parent chemokines, either alone or in combination. The chemokine chimera induced an augmented anti-tumor immunity and a marked decrease in tumor vasculature. Antibody neutralization studies indicated that CXCL10 and CXCL11 moieties of ITIP were responsible for anti-angiogenesis and chemotaxis in antitumor response, respectively. These results indicated that integrating individual functional moieties of CXCL10 and CXCL11 into a chimeric chemokine could lead to a synergistic antitumor effect. Thus, this integration strategy holds promise for chemokine-based multiple targeted therapy of cancer.

Platelet granule secretion continuously prevents intratumor hemorrhage

Cancer is associated with a prothrombogenic state capable of platelet activation. Platelets, on the other hand, can support angiogenesis, a process involved in the progression of tumor growth and metastasis. However, it is unclear whether platelet/tumor interactions substantially contribute to tumor physiology. We investigated whether platelets stabilize tumor vessels and studied the underlying mechanisms. We induced severe acute thrombocytopenia in mice bearing s.c. Lewis lung carcinoma or B16F10 melanoma. Intravital microscopy revealed that platelet depletion led to a rapid destabilization of tumor vessels with intratumor hemorrhage starting as soon as 30 min after induction of thrombocytopenia. Using an inhibitor of glycoprotein Ibalpha (GPIbalpha) and genetically engineered mice with platelet adhesion defects, we investigated the role of platelet adhesion receptors in stabilizing tumor vessels. We found that a single defect in either GPIbalpha, von Willebrand factor, P-selectin, or platelet integrin activation did not lead to intratumor hemorrhage. We then compared the ability of transfused resting and degranulated platelets to prevent intratumor hemorrhage. Whereas resting platelets prevented thrombocytopenia-induced tumor bleeding, circulating degranulated platelets did not. This suggests that the prevention of intratumor hemorrhage by platelets relies on the secretion of the content of platelet granules. Supporting this hypothesis, we further found that thrombocytopenia dramatically impairs the balance between propermeability and antipermeability factors in tumor-bearing animals, in particular depleting blood of angiopoietin-1 and serotonin. Our results show a crucial contribution of platelets to tumor homeostasis through continuous prevention of severe intratumor hemorrhage and consequent cell death. The study also suggests platelet function as a reasonable target for specific destabilization of tumor vessels.

Targeting matrix metalloproteinases and endothelial cells with a fusion peptide against tumor

Development of novel therapy for patients with tumor is still a challenge at the present time. We designed a fusion peptide (RK5) with two targets as a novel agent against tumor. The fusion peptide RK5 containing the kringle 5 fragment of human plasminogen and a decapeptide (CTTHWGFTLC) was constructed and expressed in yeast. Matrix metalloproteinase (MMP) activity, proliferation, and migration of endothelial cells were examined in vitro, respectively. Angiogenesis, tumor growth, metastasis, and survival time were evaluated in in vivo models. Administration of RK5 was delivered by both protein and gene approach. The results showed that RK5 inhibited the activity of MMP-9 and exhibited more inhibitory effects on proliferation and migration of endothelial cells than that of kringle 5 fragment and decapeptide individually. RK5 also inhibited angiogenesis, tumor growth, and metastasis and increased survival time of mice bearing tumor. In addition, the effectiveness of RK5 could be achieved by both protein and gene delivery. In conclusion, RK5 has potential to inhibit tumor growth and metastasis and to prolong survival time of animals bearing tumor. Therefore, fusion peptide RK5 with two targets provides a new design for the development of antitumor drugs and has potential for clinical application.

Expression of the chemokine receptor CCR6 in the Lewis lung carcinoma (LLC) cell line reduces its metastatic potential in vivo

Chemokines and their receptors play important roles in various aspects of tumoral processes, and evidence was provided for their critical involvement in determining the metastatic destination of tumor cells. Here, we analyzed in vitro and in vivo, how CCR6 expression could alter the behavior of Lewis lung carcinoma (LLC) cells, which were shown to express low levels of the CCR6 ligand, CCL20 (LARC), both in vitro and in vivo. The expression of CCR6 significantly decreased the number of metastases in immunocompetent C57BL/6 mice, without affecting the tumor-forming ability of LLC cells. This was correlated with a decrease in clonogenicity in soft and hard agar, and with increased adhesion to type-IV collagen. These two observations made in basal conditions were enhanced when CCL20 was added to the assay medium. Thus, expression of CCR6 in tumor cells, associated with the local production of CCL20, decreased the metastatic potential of the LLC line. We propose a model, in which the expression of a chemokine receptor in tumor cells can act as a metastasis-suppressor, or a metastasis-promoting factor, according to the expression, or the absence of expression of the cognate ligand(s) in the tumor.

Inhibition of tumorigenesis by intratumoral delivery of the circadian gene mPer2 in C57BL/6 mice

Biological clocks are intrinsic time-keeping systems that regulate behavior and physiological functions in most living organisms. Previous works suggested a possible link between the endogenous circadian clock and cell cycle regulation. The mammalian Period-2 gene (mPer2), an important component of the circadian clock mechanism, is recently demonstrated to play an important role in repressing tumor growth. In this study, we found that polyethylenimine-mediated intratumoral Per2 gene delivery had significant antitumor effects in C57BL/6 mice transplanted with Lewis lung carcinoma. Our data illustrated that the Per2 gene delivery inhibited PCNA expression and induced apoptosis. Our results support the emerging role of the circadian clock in critical aspects of tumorigenesis. These findings underscore the potential use of Per2 gene delivery as a novel therapeutic intervention for the treatment of malignant tumors.

Inhibition of tumor growth and tumor metastasis by a Chinese herbal formula--ZYD88, in an animal model with metastatic Lewis lung carcinoma

Tumor metastasis is the leading cause of cancer death. In the present study, we determined the effectiveness of ZYD88, a Chinese herbal formula, in the inhibition of tumor growth and distant tumor metastases to the lung and liver in an animal model with metastatic Lewis lung carcinoma (LLC). Treatment with ZYD88 in adult C57BL/6 mice with metastatic LLC produced dose-dependent deceases in primary tumor weight, the mitotic tumor cell number, microvessel density, distant tumor metastases and red blood cell immune complexes, while it significantly increased tumor necrosis, thymus cortical thickness, the thymus medullar reticular epithelial cell (REC) number, and the activity of red blood cell C3b receptors. Although cyclophosphamide inhibited tumor growth, it had no significant effects on distant tumor metastases, thymus cortical thickness, the thymus medullar REC number, red blood cell C3b receptor activity and red blood cell immune complexes. These results indicate that ZYD88 possesses significant anti-angiogenic, anti-tumor and anti-metastatic effects in this animal model, and warrants further investigation.

Prophylactic naked DNA vaccination with the human vascular endothelial growth factor induces an anti-tumor response in C57Bl/6 mice

Passive immunotherapy against soluble pro-angiogenic factors and/or their receptors in endothelial cells has become a promising approach in cancer therapeutics. There is also experimental evidence indicating that an active immunotherapy strategy directed towards these target molecules could also be effective. In this paper we show that it is possible to reduce tumor growth or increase the survival of tumor-bearing C57Bl/6 mice when animals are vaccinated with the human vascular endothelial growth factor (VEGF) isoform 121 gene (hVEGF(121)), and later challenged with melanoma or lung carcinoma tumor cells. Immunization was done with 10 microg DNA doses of the hVEGF121 gene, which is highly homologous to its mouse counterpart, administered on a weekly basis using a plasmid bearing 5 CpG bacterial motifs. Histopathology analyses of tumors of hVEGF(121) immunized animals showed a decrease in tumor cell density around vessels and in mitotic figures, as well as an increase in apoptotic tumor cells. A statistically significant cell cytotoxic response was found when spleen cells of immunized mice were co-cultured in vitro with mouse tumor VEGF-producing cells. Vaccination with an hVEGF121 gene mutated to make it deficient for VEGF receptor binding, produced similar in vitro and in vivo results, and significantly reduced the number of spontaneous metastases produced by the mouse Lewis lung carcinoma. Our results indicate that human VEGF DNA can be employed for anti-angiogenic active immunotherapy in mice, and that direct cell cytotoxicity is a contributor mechanism to the overall anti-tumor effects seen in immunized animals.

Hyporesponsiveness to natural killer T-cell ligand alpha-galactosylceramide in cancer-bearing state mediated by CD11b+ Gr-1+ cells producing nitric oxide

CD1d-restricted natural killer T (NKT) cells are a potential therapeutic target for cancer, for which several clinical trials have already been reported. NKT cells are specifically activated by a synthetic glycolipid, alpha-galactosylceramide (alpha-GalCer). However, it is known that, in human cancer patients, NKT cells express a degree of hyporesponsiveness to alpha-GalCer. In this study, we have examined the mechanism by which hyporesponsiveness to alpha-GalCer can be induced. In cancer-bearing mice, alpha-GalCer-induced NKT cell expansion, cytokine production, cytotoxicity, and antimetastatic effect in vivo were all significantly impaired. In fact, alpha-GalCer could eliminate metastatic disease in naive animals but failed to protect cancer-bearing mice. CD11b(+) Gr-1(+) cells were particularly increased in cancer-bearing mice and were necessary and sufficient for the suppression of the alpha-GalCer response in a nitric oxide-mediated fashion. Administration of a retinoic acid to cancer-bearing mice reduced the population of CD11b(+) Gr-1(+) cells and effectively restored alpha-GalCer-induced protection. These results show a novel feature of NKT cell function in cancer. Furthermore, our data suggest a new strategy to enhance NKT cell-mediated anticancer immune responses by suppressing CD11b(+) Gr-1(+) cell functions.

Angiopoietin-like 4 prevents metastasis through inhibition of vascular permeability and tumor cell motility and invasiveness

Angiopoietin-like 4 (ANGPTL4), a secreted protein of the angiopoietin-like family, is induced by hypoxia in both tumor and endothelial cells as well as in hypoxic perinecrotic areas of numerous cancers. Here, we investigated whether ANGPTL4 might affect tumor growth as well as metastasis. Metastatic 3LL cells were therefore xenografted into control mice and mice in which ANGPTL4 was expressed by using in vivo DNA electrotransfer. Whereas primary tumors grew at a similar rate in both groups, 3LL cells metastasized less efficiently to the lungs of mice that expressed ANGPTL4. Fewer 3LL emboli were observed in primary tumors, suggesting that intravasation of 3LL cells was inhibited by ANGPTL4. Furthermore, melanoma B16F0 cells injected into the retro-orbital sinus also metastasized less efficiently in mice expressing ANGPTL4. Although B16F0 cells were observed in lung vessels, they rarely invaded the parenchyma, suggesting that ANGPTL4 affects extravasation. In addition, recombinant B16F0 cells that overexpress ANGPTL4 were generated, showing a lower capacity for in vitro migration, invasion, and adhesion than control cells. Expression of ANGPTL4 induced reorganization of the actin cytoskeleton through inhibition of actin stress fiber formation and vinculin localization at focal contacts. Together, these results show that ANGPTL4, through its action on both vascular and tumor compartments, prevents the metastatic process by inhibiting vascular activity as well as tumor cell motility and invasiveness.

Vaccination with Viable Human Umbilical Vein Endothelial Cells Prevents Metastatic Tumors by Attack on Tumor Vasculature with Both Cellular and Humoral Immunity

PURPOSE

Because tumor endothelium is rarely targeted by immunity but is critically important for tumor growth, the immunity against tumor endothelium is to be developed as a novel antitumor strategy.

EXPERIMENTAL DESIGN

First, viable human umbilical vein endothelial cells (HUVEC) were immunized to C57BL/6 and BALB/c mice to evoke specific CTLs as well as antibodies against tumor endothelium. Lewis lung carcinoma or myeloma cells were subsequently inoculated to evaluate the effect on tumor growth by vaccination. Second, the effect on tumor metastasis by vaccination was studied using tumor-resected mice receiving HUVEC immunization 3 days after excision. Third, the immune sera and T lymphocytes from HUVEC-immunized mice were transferred to tumor-bearing mice and added to cultured HUVECs to investigate their antiproliferative effect.

RESULTS

Viable HUVEC immunization showed potent antitumor effects in Lewis lung carcinoma and myeloma tumor models. Both immune sera and CTL inhibited tumor growth and specifically suppressed proliferation of HUVECs. Particularly, tumors entirely disappeared on day 90 after tumor inoculation in four of six tumor-bearing mice receiving CTL therapy. In a metastatic tumor model, we found that the HUVEC vaccination prolonged life span from 30.9 to 41.5 days after tumor resection compared with PBS-treated mice without apparent side effects.

CONCLUSIONS

Vaccination with viable HUVECs evoked both humoral and cellular immunity against tumor microvasculature, and therefore significantly inhibited tumor growth and prolonged life span of tumor-resected mice. This may provide with a novel treatment for metastatic tumors. Moreover, we have established a convenient method to evoke specific CTL against tumor angiogenesis.

Host and Direct Antitumor Effects and Profound Reduction in Tumor Metastasis with Selective EP4 Receptor Antagonism

Prostaglandin E(2) (PGE(2)), one of the major metabolites of cyclooxygenase-2, has been implicated in tumorigenesis and tumor progression in several human cancers, including colorectal and lung. Here, we show that one of the PGE(2) receptors, the EP4 receptor, plays an important role in metastasis in both of these tumor types. Using i.v. injected Lewis lung carcinoma (3LL), we found that tumor metastasis to lung was significantly reduced when mice were treated with a specific EP4 antagonist ONO-AE3-208 or when EP4 receptor expression was knocked down in the tumor cells using RNA interference technology. Host EP4 receptors also contributed to tumor metastasis and tumor growth with decreased metastasis and tumor growth observed in EP4 receptor knockout animals. In vitro tumor cell adhesion, motility, invasion, colony formation, and Akt phosphorylation were all significantly inhibited when 3LL cells were treated with the EP4 receptor-specific antagonist. When the cells were treated with an EP4-specific agonist (AE1-734), we observed a worsening of these same features in vitro. Treatment with ONO-AE3-208 also profoundly decreased liver metastases after intrasplenic injection of MC26 colon cancer cells. Our data show that selective antagonism of EP4 receptor signaling results in a profound reduction in lung and colon cancer metastasis. Selective antagonism of the EP4 receptor may thus represent a novel therapeutic approach for the treatment of cancer and especially its propensity to metastasize.

Antibody-directed targeting of angiostatin's receptor annexin II inhibits Lewis Lung Carcinoma tumor growth via blocking of plasminogen activation: Possible biochemical mechanism of angiostatin's action

Angiostatin, the N-terminal four kringles (K1-4) of parent molecule plasminogen, is reported to block Lewis Lung Carcinoma (LLC) tumor growth and metastasis. However, angiostatin's mechanism of action is unclear. We earlier reported that angiostatin binds to cell surface annexin II through the lysine-binding domain (kringles 1-4) [Tuszynski, G.P., Sharma, M., Rothman, V.L., Sharma, M.C., 2002. Angiostatin binds to tyrosine kinase substrate annexin II through the lysine-binding domain in endothelial cells. Microvasc. Res. 64:448-462.]). We now show that annexin II on the cell surface of LLC cells regulates conversion of plasminogen to plasmin. Activation of plasminogen to plasmin is time-dependent, with the linear activation lasting up to 120 min. Monoclonal antibodies to annexin II reduced plasminogen activation by 92.6%, suggesting a specific role of annexin II in plasmin generation. Angiostatin also reduced plasmin generation by 81.6%, suggesting that angiostatin may be competing with plasminogen through lysine-binding domain. epsilon-Aminocaproic acid, a lysine analogue, effectively blocked plasminogen activation indicating that, indeed, the lysine-binding site of the kringles domain is required for activation. These data suggest that annexin II may be a receptor target for angiostatin's action. Therefore, we tested the effect of high affinity monoclonal antibody to annexin II in mouse model of LLC. A single dose of antibody treatment inhibited LLC tumor growth almost 70% with concomitant inhibition of circulating plasmin generation and its proteolytic activity. Taken together, it is possible that inhibition of LLC tumor growth and metastasis reported by angiostatin therapy may be due to blocking of annexin-II-dependent plasmin generation. Plasmin is known to influence angiogenic, invasive and metastatic capability of tumors.

Caffeoyl pyrrolidine derivative LY52 inhibits tumor invasion and metastasis via suppression of matrix metalloproteinase activity

BACKGROUND

LY52 is a caffeoyl pyrrolidine derivative designed to fit and extend into the active pocket of matrix metalloproteinase (MMP). In this study, the effects of LY52 on MMP-2 and MMP-9 activities and tumor invasion and metastasis were examined.

MATERIALS AND METHODS

MMP expression in SKOV3 cells was analyzed by gelatin zymography. The anti-invasion and anti-metastasis abilities of LY52 were evaluated with penetration of SKOV3 cells through Matrigel-coated membrane in vitro and pulmonary metastasis of Lewis lung carcinoma in mice, respectively.

RESULTS

LY52 significantly blocked the proteolytic activity of gelatinase. Gelatin zymography revealed that MMP-2 and MMP-9 expressions in SKOV3 cells were reduced in the presence of LY52. LY52 also suppressed SKOV3 cell invasion in vitro. Furthermore, a significant inhibition of pulmonary metastasis of Lewis lung carcinoma cells was observed in LY52-administrated mice.

CONCLUSION

LY52 might suppress invasion and metastasis of carcinoma cells via inhibition of MMP-2 and MMP-9 proteolytic activities.

Hybrid-primed lymphocytes and hybrid vaccination prevent tumor growth of lewis lung carcinoma in mice

Dendritic cell (DC)-tumor cell hybrids are currently being evaluated as a novel antitumor vaccination strategy. We have explored in an animal model whether administration of DCs fused with poorly immunogenic carcinoma cells could elicit an antitumor response. Fusion of C57/BL6 mice bone marrow-derived DCs with Lewis lung carcinoma (LLC1) cells resulted in approximately 50% fusion efficiency. Hybrid cells (HCs) were used to explore 3 potential tumor therapy strategies: protective immunization, vaccination, and adoptive cellular therapy. Immunization with HCs induced activation of proliferating cytotoxic T cells, upregulation of distinct cytokines genes, and a significant retardation of tumor growth. Similar results were observed by vaccination with HCs in the tumor-bearing host. Finally, when T cells from HC-vaccinated mice were transferred into naive tumor-bearing mice, tumor growth was strongly retarded and an efficient proliferative and cytotoxic T-cell response was observed. Tumor growth was reduced by more than 50%, and tumor development was significantly delayed. Taken together, we demonstrate that HCs offer effective immunotherapy of poorly immunogenic carcinomas. This is independent of whether the HCs are taken for adoptive transfer or as a vaccine.

Full-length ADAMTS-1 and the ADAMTS-1 fragments display pro- and antimetastatic activity, respectively

The exact role of a disintegrin and metalloproteinase with thrombospondin motifs-1 (ADAMTS-1) and the underlying mechanism of its involvement in tumor metastasis have not been established. We have now demonstrated that overexpression of ADAMTS-1 promotes pulmonary metastasis of TA3 mammary carcinoma and Lewis lung carcinoma cells and that a proteinase-dead mutant of ADAMTS-1 (ADAMTS-1E/Q) inhibits their metastasis, indicating that the prometastatic activity of ADAMTS-1 requires its metalloproteinase activity. Overexpression of ADAMTS-1 in these cells promoted tumor angiogenesis and invasion, shedding of the transmembrane precursors of heparin-binding epidermal growth factor (EGF) and amphiregulin (AR), and activation of the EGF receptor and ErbB-2, while overexpression of ADAMTS-1E/Q inhibited these events. Furthermore, we found that ADAMTS-1 undergoes auto-proteolytic cleavage to generate the NH(2)- and COOH-terminal cleavage fragments containing at least one thrombospondin-type-I-like motif and that overexpression of the NH(2)-terminal ADAMTS-1 fragment and the COOH-terminal ADAMTS-1 fragment can inhibit pulmonary tumor metastasis. These fragments also inhibited Erk1/2 kinase activation induced by soluble heparin-binding EGF and AR. Taken together, our results suggest that the proteolytic status of ADAMTS-1 determines its effect on tumor metastasis, and that the ADAMTS-1E/Q and the ADAMTS-1 fragments likely inhibit tumor metastasis by negatively regulating the availability and activity of soluble heparin-binding EGF and AR.

Ten tandem repeats of beta-hCG 109-118 enhance immunogenicity and anti-tumor effects of beta-hCG C-terminal peptide carried by mycobacterial heat-shock protein HSP65

The beta-subunit of human chorionic gonadotropin (beta-hCG) is secreted by many kinds of tumors and it has been used as an ideal target antigen to develop vaccines against tumors. In view of the low immunogenicity of this self-peptide,we designed a method based on isocaudamer technique to repeat tandemly the 10-residue sequence X of beta-hCG (109-118), then 10 tandemly repeated copies of the 10-residue sequence combined with beta-hCG C-terminal 37 peptides were fused to mycobacterial heat-shock protein 65 to construct a fusion protein HSP65-X10-betahCGCTP37 as an immunogen. In this study, we examined the effect of the tandem repeats of this 10-residue sequence in eliciting an immune by comparing the immunogenicity and anti-tumor effects of the two immunogens, HSP65-X10-betahCGCTP37 and HSP65-betahCGCTP37 (without the 10 tandem repeats). Immunization of mice with the fusion protein HSP65-X10-betahCGCTP37 elicited much higher levels of specific anti-beta-hCG antibodies and more effectively inhibited the growth of Lewis lung carcinoma (LLC) in vivo than with HSP65-betahCGCTP37, which should suggest that HSP65-X10-betahCGCTP37 may be an effective protein vaccine for the treatment of beta-hCG-dependent tumors and multiple tandem repeats of a certain epitope are an efficient method to overcome the low immunogenicity of self-peptide antigens.

The ubiquitin-proteasome system plays essential roles in presenting an 8-mer CTL epitope expressed in APC to corresponding CD8+ T cells

MUT1 is an H-2Kb-restricted 8-mer CTL epitope expressed in Lewis lung carcinoma (3LL) tumor cells derived from C57BL/6 (B6) mice. We constructed a chimeric gene encoding ubiquitin-fused MUT1 (pUB-MUT1). By using a gene gun, B6 mice were immunized with the gene prior to challenge with 3LL tumor cells. Tumor growth and lung metastasis were prominently suppressed in mice immunized with pUB-MUT1 but only slightly in those immunized with the MUT1 gene (pMUT) alone. CD8+ T cells were confirmed to be the final effector by in vitro experiments and in vivo removal of the cells with a corresponding antibody. Anti-tumor immunity was profoundly suppressed in mice deficient in an immuno-subunit of proteasome, LMP7. Furthermore, mice deficient in a proteasome regulator, PA28alpha/beta, failed to acquire protective immunity. Thus, application of the ubiquitin-fusion degradation pathway was useful even in immunization with genes encoding a single CTL epitope for induction of specific and active CD8+ T cells.

Resveratrol, a natural diphenol, reduces metastatic growth in an experimental cancer model

Administration of different doses of the diphenol resveratrol had no effect on the growth of an intramuscularly implanted experimental tumour, the Lewis lung carcinoma. These results do not agree with previous reports where a clear effect of resveratrol was shown on tumour burden in both mice and rats. However, administration of the diphenol had a clear anti-metastatic effect, decreasing both the number and the weight of the lung metastases. Similar effects were observed both at 5 and 25mg/kg body weight per day, resulting in an approximately 40% reduction in the number of metastases. These results suggest that resveratrol could be tentatively given as a preventive agent in cancer patients undergoing radiotherapy or chemotherapy.

[The effect of preliminary administration of water with reduced deuterium content on the growth of transplantable tumors in mice]

It was investigated whether preliminary administration of water with reduced Deuterium content may modify the inhibitory effect of the water given to BDF1 and CDA mice on the day of tumor transplantation. Two models were used: Lewis lung carcinoma (LLC) and uterine cervical carcinoma (UCC). Experimental mice (20 per group) used the water with reduced Deuterium content. Water with a Deuterium content close to that of drinking water was given to controls (30 per group). Both kinds of water were given to mice 4 weeks before the experiment. Inhibitory effect was acknowledged by the time at which the first nodules appeared at site of transplantation and assessed with respect to volume of tumor and animal life-span. Metastasis inhibition coefficient was determined for Lewis carcinoma metastasizing to the lung. It was found that water with reduced Deuterium content effectively inhibited the growth of the transplantable tumors under study, significantly reduced metastasis weight in mice with LLC and increased life-span in animals with transplantable UCC.

Inhibition of heme oxygenase-1 by zinc protoporphyrin IX reduces tumor growth of LL/2 lung cancer in C57BL mice

Heme oxygenase (HO)-1 is a key player reducing cytotoxicity and enhancing protumoral effects of nitric oxide (NO). We examined zinc protoporphyrin (ZnPP) IX, an HO-1 inhibitor, to affect tumor growth of LL/2 mouse lung cancer cells. ZnPPIX reduced HO-1 expression and HO activity in LL/2 cells, whereas cobalt PPIX (CoPPIX), an HO-1 activator, increased both. LL/2 cells treated with sodium nitropurusside, an NO donor, showed growth inhibition dose-dependently, which was enhanced by ZnPPIX cotreatment, but was reduced by CoPPIX. In mice tumors, ZnPPIX decreased HO-1 expression. LL/2-tumors were found in 88% (7/8) vehicle-treated mice, whereas tumors were found in 38% (3/8) and 25% (2/8) mice treated with 5 and 20 microg/mouse ZnPPIX, respectively (p = 0.0302). Tumor growth was inhibited dose-dependently by ZnPPIX. Vascular endothealial growth factor concentration in tumors was reduced by ZnPPIX (p = 0.0341). Microvessel density (MVD) in ZnPPIX-treated tumors was lower than that in vehicle-treated tumors (p = 0.0362). Apoptotic cell count in ZnPPIX-treated tumors was higher than that in vehicle-treated tumors (p = 0.0003). In contrast, CoPPIX treatment increased HO-1 expression, enhanced tumorigenicity and MVD and reduced apoptosis. From these findings, inhibition of HO-1 by ZnPPIX provides relevant antitumoral effects.

[An anti-tumor research of recombinant phage vaccine expressed xenogenic EGFR]

A recombinant phage vaccine expressing EGFR on it's capsid was constructed and used to study the anti-tumor effect. The T7 phage display system was applied to display seven xenogenic (human, chicken) epidermal growth factor receptor extracellular domain fragments. The EGFR fragment was expressed as fused protein with 10B capsid on the surface of T7 phage. The T7-EGFR phage vaccines were injected into C57BL/6J mice, and then Lewis lung cancer cells were inoculated after 4 weeks immunization. The tumor tissue was excised and weighed after 10 days to evaluate the anti-tumor effect of each experimental group. The EGFR expression of the phage vaccine was verified by western-blot analysis. The A431 cells with high expressed EGFR was used to detect the anti-EGFR antibody by flow cytometry analysis. The results showed that the A431 cell can react with the serum obtained from the mice after three-week immunization. The experimental results confirmed that special EGFR antibody could be induced by the T7-EGFR phage vaccine. The T7-EGFR phage vaccine can elicit endogenous special EGFR antibody in mice and is capable of suppressing the tumor proliferation and retarding the growth of Lewis lung cancer. This research can be used to develop an anti-tumor vaccine for the target-therapy of EGFR(+) tumor.

Controlled release of paclitaxel from photocrosslinked chitosan hydrogels and its subsequent effect on subcutaneous tumor growth in mice

A photocrosslinkable chitosan (Az-CH-LA) aqueous solution containing paclitaxel resulted in an insoluble hydrogel within 30 s of ultrtaviolet light (UV)-irradiation. About 35-40% of the paclitaxel was released from the paclitaxel-incorporated chitosan hydrogel into phosphate buffered saline (PBS) within 1 day, after which gradual release occurred during 3 days under in vitro non-degradation conditions of the hydrogel. The paclitaxel remaining in the chitosan hydrogel retained its biological activity in vitro for at least 21 days, and was released from the chitosan hydrogel in vivo upon degradation of the hydrogel. The paclitaxel-incorporated Az-CH-LA hydrogel inhibited the growth of subcutaneously induced tumors with Lewis lung cancer (3LL) cells more effectively than those treated with only Az-CH-LA, only paclitaxel, and a non-treated group (control) for at least 11 days. Furthermore, paclitaxel-incorporated chitosan hydrogel markedly reduced the number of CD34-positive vessels in subcutaneous 3LL tumors, indicating a strong inhibition of angiogenesis. These results suggested that application of paclitaxel-incorporated Az-CH-LA hydrogel has an inhibitory activity on angiogenesis and tumor growth.

Cyclooxygenase 2 inhibition promotes IFN-gamma-dependent enhancement of antitumor responses

In previous studies, we demonstrated an immune suppressive network in non-small cell lung cancer that is due to overexpression of tumor cyclooxygenase 2 (COX-2). In this study, we assessed the vaccination response to tumor challenge following either pharmacological or genetic inhibition of COX-2 in a murine lung cancer model. Treatment of naive mice with the COX-2 inhibitor, SC-58236, skewed splenocytes toward a type 1 cytokine response, inducing IFN-gamma, IL-12, and IFN-gamma-inducible protein 10, whereas the type 2 cytokines IL-4, IL-5, and IL-10 remained unaltered. Fifty percent of mice receiving SC-58236 and an irradiated tumor cell vaccine completely rejected tumors upon challenge. Those mice that did form tumors following challenge demonstrated a reduced tumor growth. In contrast, all mice either vaccinated with irradiated tumor cells alone or receiving SC-58236 alone showed progressive tumor growth. Studies performed in CD4 and CD8 knockout mice revealed a requirement for the CD4 T lymphocyte subset for the complete rejection of tumors. To determine the role of host COX-2 expression on the vaccination responses, studies were performed in COX-2 gene knockout mice. Compared with control littermates, COX-2(-/-) mice showed a significant tumor growth reduction, whereas heterozygous COX-2(-/+) mice had an intermediate tumor growth reduction following vaccination. In vivo depletion of IFN-gamma abrogated the COX-2 inhibitor-mediated enhancement of the vaccination effect. These findings provide a strong rationale for additional evaluation of the capacity of COX-2 inhibitors to enhance vaccination responses against cancer.

Protective immunity against disparate tumors is mediated by a nonpolymorphic MHC class I molecule

Current peptide-based immunotherapies for treatment of model cancers target tumor Ags bound by the classical MHC class I (class Ia) molecules. The extensive polymorphism of class Ia loci greatly limits the effectiveness of these approaches. We demonstrate in this study that the murine nonpolymorphic, nonclassical MHC class I (class Ib) molecule Q9 (Qa-2) promotes potent immune responses against multiple syngeneic tumors. We have previously shown that ectopic expression of Q9 on the surface of class Ia-negative B78H1 melanoma led to efficient CTL-mediated rejection of this tumor. In this study, we report that surface-expressed Q9 on 3LLA9F1 Lewis lung carcinoma and RMA T cell lymphoma also induces potent antitumor CTL responses. Importantly, CTL harvested from animals surviving the initial challenge with Q9-positive 3LLA9F1, RMA, or B78H1 tumors recognized and killed their cognate tumors as well as the other cancer lines. Furthermore, immunization with Q9-expressing 3LLA9F1 or RMA tumor cells established immunological memory that enhanced protection against subsequent challenge with a weakly immunogenic, Q9-bearing melanoma variant. Collectively, the generation of cross-reactive CTL capable of eliminating multiple disparate Q9-expressing tumors suggests that this nonpolymorphic MHC class I molecule serves as a restriction element for a shared tumor Ag(s) common to lung carcinoma, T cell lymphoma, and melanoma.

Suppressing effects of daily oral supplementation of beta-glucan extracted from Agaricus blazei Murill on spontaneous and peritoneal disseminated metastasis in mouse model

PURPOSE

The Basidiomycete fungus Agaricus blazei Murill has traditionally been used as a health food for the prevention of cancer.

METHODS

We examined whether beta-(1-6)-D: -glucan extracted from A. blazei is a potential anticancer agent in an in vitro and in vivo animal model.

RESULTS

Here we show that (1) beta-glucan had cytotoxic effect against human ovarian cancer HRA cells, but not against murine Lewis lung cancer 3LL cells, in vitro; (2) beta-glucan promotes p38 MAPK activity for suppressing HRA cell proliferation and amplifying the apoptosis cascade; (3) beta-glucan stimulates translocation of the proapoptotic protein, Bax, from the cytosol to mitochondria, cytochrome c release, and subsequent caspase-9 activation; (4) treatment with SB203580, a p38 MAPK-specific inhibitor, suppresses beta-glucan-induced effects, indicating that activation of p38 MAPK is involved in the suppression of cell proliferation and mitochondrial activation-mediated cell death pathway; (5) in mice, oral supplementation with beta-glucan reduces pulmonary metastasis of 3LL cells and peritoneal disseminated metastasis of HRA cells and inhibits the growth of these metastatic tumors in lung or peritoneal cavity, in part, by suppressing uPA expression; and (6) in an in vivo experimental metastasis assay, however, the oral supplementation with beta-glucan after i.v. tumor cell inoculation did not reduce the number of lung tumor colonies.

CONCLUSION

Treatment with beta-glucan may be beneficial for cancer patients with or at risk for metastasis. The beta-glucan-dependent signaling pathways are critical for our understanding of anticancer events and development of cancer therapeutic agents.

Inhibition of hepatocellular carcinomas in vitro and hepatic metastases in vivo in mice by the histone deacetylase inhibitor HA-But

PURPOSE

The purpose is to evaluate the CD44-mediated cellular targeting of HA-But, a hyaluronic acid esterified with butyric acid (But) residues, to hepatocellular carcinoma cell lines in vitro and to hepatic tumor metastases in vivo.

EXPERIMENTAL DESIGN

In vitro, the CD44-dependent cytotoxicity in two human hepatocellular carcinoma cell lines (HepB3 and HepG2) with high and low CD44 expression was investigated; in vivo, the effect on liver metastases originating from intrasplenic implants of Lewis lung carcinoma (LL3) or B16-F10 melanoma in mice was compared with the pharmacokinetics of organ and tissue distribution using different routes of administration.

RESULTS

HepB3 and HepG2 cell lines showed different expression of CD44 (78 and 18%, respectively), which resulted in a CD44-dependent HA-But inhibitory effect as demonstrated also by the uptake analysis performed using radiolabeled HA-But ((99m)Tc-HA-But). Pharmacokinetic studies showed different rates of (99m)Tc-HA-But distribution according to the route of administration (i.v., i.p., or s.c.): very fast (a few minutes) after i.v. treatment, with substantial accumulation in the liver and spleen; relatively slow after i.p. or s.c. treatment, with marked persistence of the drug at the site of injection. The effect of s.c. and i.p. treatment with HA-But on liver metastases originating from intrasplenic implants of LL3 carcinoma or B16-F10 melanoma (both CD44-positive: 68 and 87%, respectively), resulted in 87 and 100% metastases-free animals, respectively (regardless of the route of administration), and a significant prolongation of the life expectancy compared with control groups.

CONCLUSIONS

HA-But tends to concentrate in the liver and spleen and appears to be a promising new drug for the treatment of intrahepatic tumor lesions.

New anticancer agents: in vitro and in vivo evaluation of the antitumor and antimetastatic actions of various compounds isolated from medicinal plants

In this review, in the search for the development of new anticancer drugs, the effects of compounds isolated from various medicinal plants on tumor growth and metastasis, using mice bearing a highly metastatic drug-resistant mouse tumor, were studied. The antitumor and antimetastatic actions of stilbene derivatives isolated from Polygonum and Cassia species were examined. Among the stilbene derivatives, resveratrol and cassiagrol A (stilbene dimer) displayed antitumor and antimetastatic actions through the inhibition of tumor-induced neovascularization in in vitro and in vivo models. It was found that two chalcone derivatives from Angelica keiskei roots also inhibited tumor growth and metastasis in tumor-bearing mice through the inhibition of tumor-induced neovascularization and/or the inhibition of immune suppression caused by tumors. Recently, basidiomycete fungi have been used for the treatment of cancer. Then, the low molecular weight substances were isolated from Agaricus blazei and Ganoderma lucidum as antitumor and antimetastatic substances. It is suggested that these substances of basidiomycete also inhibited tumor growth and metastasis to the lung through the inhibition of tumor-induced neovascularization and/or the inhibition of immune suppression caused by tumors.

[Studies on the enhancement of DC vaccine to mouse Lewis lung cancer by CpG oligonucleotides]

OBJECTIVE

To investigate whether CpG ODN can affect the antitumor responses of DC-tumor cell vaccine against Lewis lung cancer.

METHODS

CpG oligonucleotides 1826 (ODN 1826) were used to promote maturation of DCs in vitro. By fusing DCs with Lewis lung carcinoma L3-8 cells, DC-based tumor cell vaccines were developed. To determine the immune responses to the vaccines, T cell proliferation and cytotoxicity were done in vitro. Therapeutic and prophylactic immunization with DC vaccines were performed in C57BL/6 mice bearing Lewis lung carcinoma.

RESULTS

Bone marrow cells cultured in the presence of GM-CSF and IL-4 plus additional ODN 1862 appeared typical morphology of DCs. FACS analyses showed that the mean fluorescence index (MFI) of CD40 expression of DCs stimulated with and without CpG ODN was 24 and 11, respectively, and that of CD86 expression was 75 and 33, respectively. IL-12 secreted by DCs cultured with ODN 1826 was 10-fold as high as that without ODN 1826. Significant T-cell proliferation and T cell-mediated cytotoxicity against L3-8 was induced in vitro. Marked inhibition of tumor growth in L3-8 bearing mice was observed upon prophylactic and therapeutic immunizations with the vaccine.

CONCLUSION

CpG ODN can enhance the antitumor responses of DC vaccine by promoting DC maturation.

Isolation of an anti-angiogenic substance from Agaricus blazei Murill: its antitumor and antimetastatic actions

We previously found that ergosterol isolated from Agaricus blazei inhibited tumor growth through the inhibition of tumor-induced neovascularization. In the present study, we isolated further anti-angiogenic substances (A-1 and A-2) from this fungus using an assay system of angiogenesis induced by Matrigel supplemented with vascular endothelial growth factor, and A-1 was identified as sodium pyroglutamate. Next, we examined the antitumor and antimetastatic actions of A-1 using Lewis lung carcinoma (LLC)-bearing mice. A-1 (30, 100 and 300 mg/kg) inhibited tumor growth and metastasis to the lung. The reduction of the numbers of splenic lymphocytes, CD4+ and CD8+ T cells in LLC-bearing mice was inhibited by the oral administration of A-1 (30, 100 and 300 mg/kg). Further, A-1 increased the number of apoptotic cells of tumors and the numbers of CD8+ T and natural killer cells invading the tumors, and inhibited the increase of von Willebrand factor expression (a measure of angiogenesis) in the tumors. These results suggest that the antitumor and antimetastatic actions of A-1 (sodium pyroglutamate) may be associated with inhibition of the reduction of immune response caused by the tumor growth and tumor-induced neovascularization. This is the first report showing that sodium pyroglutamate isolated from A. blazei as an anti-angiogenic substance has potent antitumor and antimetastatic actions, as well as immune-modulatory activity, in tumor-bearing mice.

Angiopoietin-3 inhibits pulmonary metastasis by inhibiting tumor angiogenesis

Angiopoietins (Ang-1, Ang-2, and Ang-3) are the ligands of Tie-2 receptor tyrosine kinase. The essential roles of Ang-1 and Tie-2 in embryonic angiogenesis have been established, and studies have demonstrated the involvement of Ang-1 and Ang-2 in tumor angiogenesis. However, the role of Ang-3 in tumor angiogenesis and metastasis and the mechanism underlying its function are totally unknown. We have shown recently that Ang-3 is tethered on cell surface via heparan sulfate proteoglycans. In our current study, we have demonstrated that overexpression of Ang-3 inhibits pulmonary metastasis of Lewis lung carcinoma and TA3 mammary carcinoma (TA3) cells by inhibiting tumor angiogenesis and promoting apoptosis of the tumor cells. In addition, we have demonstrated that the binding of Ang-3 to the cell surface is required for the effective inhibition of Ang-3 on tumor metastasis and that Ang-3 inhibits endothelial cell proliferation and survival and blocks Ang-1- and vascular endothelial growth factor-induced activation of extracellular signal-regulated kinase 1/2 and Akt kinases, which likely underlie the Ang-3-mediated inhibition on tumor angiogenesis and metastasis.

ISCOM based vaccines for cancer immunotherapy

Immunostimulating complex (ISCOM) vaccines are particulate antigen delivery vehicles composed of saponin, cholesterol, phospholipid and immunogen. Here we illustrate that ISCOM-based vaccines represent an attractive modality for the development of anti-cancer vaccines. Using murine models and a model cancer antigen, ISCOM vaccines were shown to induce potent CD8 T cell responses, to mediate protection in three different tumor models, to promote Th1-biased immunity, and to induce CD8 T cell responses in the absence of CD4+ T cell help. The former three activities were also found to be substantially improved when the vaccine antigen was associated with the ISCOM structure. Furthermore, the presence in vivo of pre-existing antibodies against the vaccine antigen did not inhibit CD8 T cell induction by the ISCOM vaccine. Although vaccination was effective against challenge with vaccine-antigen expressing tumors, no activity against neighboring vaccine-antigen negative tumor cells was observed, indicating that determinant spreading or bystander activity does not lead to significant anti-cancer activity.

Induction of apoptosis and tumor regression by vesicular stomatitis virus in the presence of gemcitabine in lung cancer

Vesicular stomatitis virus (VSV) has been shown to replicate rapidly in vitro and kill selectively a variety of tumor cell lines. The present study was designed to determine whether gemcitabine potentiates the antitumor activity of VSV in vitro and in vivo. A549 human lung adenocarcinoma cells and LLC Lewis lung carcinoma cells were treated with VSV (0.1-10 plaque-forming units per cell) plus gemcitabine (20 nM to 20 microM). Mice bearing A549 or LLC were treated with VSV (5 x 10(4) to 1 x 10(8) plaque-forming units) daily for 5 days plus gemcitabine (5-125 mg/kg/day) once every 3 days for 4 times. Induction of apoptosis and effects on growth inhibition were assessed. The lung cancer cells treated with VSV plus gemcitabine displayed the apparently increased apoptotic cells compared with treatment with VSV or gemcitabine alone. The combined treatment with VSV plus gemcitabine induced the apparent antitumor activity with complete regression of the established lung cancer in both A549 and LLC lung cancer models and augmented the induction of apoptosis in lung cancer cells in vivo as well. This study suggests that the combined treatment with VSV plus gemcitabine may augment the induction of apoptosis in lung cancer cells in vitro and in vivo, and that the augmented antitumor activity in vivo may result from the increased induction of apoptosis in lung cancer cells. The present findings may be of importance to the further exploration of the potential application of this combined approach in the treatment of lung cancer.

alpha-Tocopheryl succinate sensitizes established tumors to vaccination with nonmatured dendritic cells

PURPOSE

Dendritic cells (DCs) are considered potential candidates for cancer immunotherapy due to their ability to process and present antigens to T cells and stimulate immune responses. However, DC-based vaccines have exhibited minimal effectiveness against established tumors in mice and human cancer patients. The use of appropriate adjuvants can enhance the efficacy of DC-based cancer vaccines in treating established tumors.

METHODS

In this study we have employed alpha-tocopheryl succinate (alpha-TOS), a nontoxic esterified analogue of vitamin E, as an adjuvant to enhance the effectiveness of DC vaccines in treating established murine Lewis lung (3LL) carcinomas.

RESULTS

We demonstrate that locally or systemically administered alpha-TOS in combination with nonmatured DCs injected intratumorally (i.t.) or subcutaneously (s.c.) significantly inhibits the growth of preestablished 10-day tumors (mean tumor volume of 77.5 +/- 17.8 mm3 on day 30 post-tumor injection) as compared to alpha-TOS alone (mean tumor volume of 471 +/- 68 mm3 on day 30 post-tumor injection). Additionally, the adjuvant effect of alpha-TOS was superior to that of cyclophosphamide (CTX). The mean tumor volume on day 28 post-tumor injection in mice treated with CTX+DCs was 611 +/- 94 mm3 as compared to 105 +/- 36 mm3 in mice treated with alpha-TOS+DCs. Analysis of purified T lymphocytes from mice treated with alpha-TOS+DC revealed significantly increased secretion of IFN-gamma as compared to T cells from the various control groups.

CONCLUSION

This study demonstrates the potential usefulness of alpha-tocopheryl succinate, an agent nontoxic to normal cell types, as an adjuvant to augment the effectiveness of DC-based vaccines in treating established tumors.

Inhibition of experimental lung metastases of Lewis lung carcinoma cells by chemically modified heparin with reduced anticoagulant activity

Heparin, a widely used anticoagulant, is known to have anti-metastatic activity, although the mechanism is not fully understood. In the present study, we investigated the mechanism of this anti-metastatic activity using periodate-oxidized and borohydride-reduced heparin with low anticoagulant activity (LAC heparin). The anticoagulant activity of LAC heparin is markedly reduced to almost the control level in terms of prothrombin time in vitro, and no hemorrhagic complication was observed with injection of LAC heparin into mice in vivo. LAC heparin injected intravenously with Lewis lung carcinoma cells or 10 min before tumor cell injection significantly inhibited, to the same extent as intact heparin and in a dose- and time-dependent manner, the lung colonization that develops after intravenous injection (i.v.) of tumor cells. Flow cytometric analysis revealed that Lewis lung carcinoma cells strongly express heparan sulfate on their surface. Both the LAC heparin and intact heparin inhibited the adhesion and invasion of tumor cells to Matrigel-coated dishes in vitro without significant effect on the tumor cell growth. LAC heparin also significantly diminished tumor cell retention in the lung after i.v. of LacZ gene-tagged Lewis lung carcinoma cells. These results suggest that LAC heparin may prevent tumor cells from attachment to the subendothelial matrix of lung capillaries by competitively inhibiting cell surface heparan sulfate functions and suppress lung colonization.

Antitumor and antimetastatic activities of 4-hydroxyderricin isolated from Angelica keiskei roots

The roots of Angelica keiskei Koizumi (Umbelliferae) have traditionally been used as a health food considered to have diuretic, laxative, analeptic and lactagogue effects. Recently, it has been thought that the roots and herbs of A. keiskei have preventive effects against coronary heart disease, hypertension and cancer. It has been reported that chalcone derivatives, such as xanthoangelol and 4-hydroxyderricin, are isolated as main components from this root. Recently, we reported that the 50 % ethanol extract, the ethyl acetate-soluble fraction and the isolated xanthoangelol, inhibited tumor growth and metastasis to the lung in Lewis lung carcinoma (LLC)-bearing mice. In the present study, we examined the effects of 4-hydroxyderricin on tumor growth and metastasis to the lung or liver in subcutaneous or intrasplenic LLC-implanted C57BL/6J female mice. 4-Hydroxyderricin at a dose of 50 mg/kg x 2/day orally inhibited the tumor growth in subcutaneous LLC-implanted mice and inhibited the lung metastasis and prolonged the survival time in mice after the removal of subcutaneous tumors by surgical operation. Doxorubicin (5 mg/kg x 2/week, i. p.) inhibited the tumor growth and metastasis to the lung, but it shortened the survival time and reduced the survival rate compared to those in 4-hydroxyderricin-treated mice. 4-Hydroxyderricin inhibited DNA synthesis in LLC cells at a concentration of 100 microM, but it had no effect on the DNA synthesis in human umbilical vein endothelial cells (HUVECs) or on the adherence of LLC cells to HUVECs. 4-Hydroxyderricin inhibited Matrigel-induced formation of capillary-like tubes by HUVECs at concentrations of 10 to 100 microM. The weights of the spleen and thymus in mice with subcutaneously implanted LLC were maintained close to those of normal mice by orally administered 4-hydroxyderricin. In addition, 4-hydroxyderricin (50 mg/kg x 2/day) inhibited the reduction of the numbers of lymphocytes, CD4+, CD8+ and natural killer (NK)-T cells in the spleen of tumor-removed mice. Doxorubicin reduced the numbers of lymphocytes, CD4+, CD8+ and NK cells compared to those in LLC-removed mice. These results suggest that the antitumor and antimetastatic activities of 4-hydroxyderricin may be modulated by the immune system and the inhibition of angiogenesis.

Depletion of CXCR2 Inhibits Tumor Growth and Angiogenesis in a Murine Model of Lung Cancer

The Glu-Leu-Arg(+) (ELR(+)) CXC chemokines are potent promoters of angiogenesis and have been demonstrated to induce a significant portion of nonsmall cell lung cancer-derived angiogenic activity and support tumorigenesis. ELR(+) CXC chemokines share a common chemokine receptor, CXCR2. We hypothesized that CXCR2 mediates the proangiogenic effects of ELR(+) CXC chemokines during tumorigenesis. To test this postulate, we used syngeneic murine Lewis lung cancer (LLC; 3LL, H-2(b)) heterotopic and orthotopic tumor model systems in C57BL/6 mice replete (CXCR2(+/+)) and deficient in CXCR2 (CXCR2(-/-)). We first demonstrated a correlation of the expression of endogenous ELR(+) CXC chemokines with tumor growth and metastatic potential of LLC tumors. Next, we found that LLC primary tumors were significantly reduced in growth in CXCR2(-/-) mice. Moreover, we found a marked reduction in the spontaneous metastases of heterotopic tumors to the lungs of CXCR2(-/-) mice. Morphometric analysis of the primary tumors in CXCR2(-/-) mice demonstrated increased necrosis and reduced vascular density. These findings were further confirmed in CXCR2(+/+) mice using specific neutralizing Abs to CXCR2. The results of these studies support the notion that CXCR2 mediates the angiogenic activity of ELR(+) CXC chemokines in a preclinical model of lung cancer.

Selective inhibition of tumor microvascular permeability by cavtratin blocks tumor progression in mice

Tumor vasculature is hyperpermeable to macromolecules compared to normal vasculature; however, the relationship between tumor hyperpermeability and tumor progression is poorly understood. Here we show that a cell-permeable peptide derived from caveolin-1, termed cavtratin, reduces microvascular hyperpermeability and delays tumor progression in mice. These antipermeability and antitumor actions of cavtratin occur in the absence of direct cytostatic or antiangiogenic effects. Cavtratin blocks microvascular permeability by inhibiting endothelial nitric oxide synthase (eNOS), as the antipermeability and antitumor actions of cavtratin are markedly diminished in eNOS knockout mice. Our results support the concepts that hyperpermeability of tumor blood vessels contributes to tumor progression and that blockade of eNOS may be exploited as a novel target for antitumor therapy.

Expression of the Mig (CXCL9) gene in murine lung carcinoma cells generated angiogenesis-independent antitumor effects

We examined whether expression of monokine induced by IFN-gamma (Mig, CXCL9) in tumors could produce antitumor effects. Murine lung carcinoma cells (A11) were retrovirally transduced with the murine Mig gene (A11/Mig) and were inoculated into syngeneic mice. Although proliferation in vitro of A11/Mig cells was not different from that of parent cells, the growth in vivo of A11/Mig tumors was significantly retarded compared with that of parent tumors. The antitumor effect was dependent on the amount of Mig produced. We compared the expression level of marker genes of lymphocytes and endothelial cells between parent and A11/Mig tumor masses with reverse transcription-polymerase chain reaction. Expression of CD4, CD8alpha, CD40, CD86, CD28, CD31 and vascular endothelial growth factor was not different between the two tumor groups but expression of CD40 ligand, CD80, NK1.1 and CXCR3 was relatively lower in A11/Mig tumors. Although Mig is a chemotactic factor for activated T and NK cells and an inhibitor for angiogenesis, the present data suggested that production of Mig in tumors did not recruit activated T and NK cells efficiently or suppress angiogenesis. The antitumor effects by Mig could be independent of anti-angiogenesis and recruitment of T and NK cells.

Physiological levels of tumstatin, a fragment of collagen IV alpha3 chain, are generated by MMP-9 proteolysis and suppress angiogenesis via alphaV beta3 integrin

We demonstrate a physiological role for tumstatin, a cleavage fragment of the alpha3 chain of type IV collagen (Col IValpha3), which is present in the circulation. Mice with a genetic deletion of Col IValpha3 show accelerated tumor growth associated with enhanced pathological angiogenesis, while angiogenesis associated with development and tissue repair are unaffected. Supplementing Col IValpha3-deficient mice with recombinant tumstatin to a normal physiological concentration abolishes the increased rate of tumor growth. The suppressive effects of tumstatin require alphaVbeta3 integrin expressed on pathological, but not on physiological, angiogenic blood vessels. Mice deficient in matrix metalloproteinase-9, which cleaves tumstatin efficiently from Col IValpha3, have decreased circulating tumstatin and accelerated growth of tumor. These results indicate that MMP-generated fragments of basement membrane collagen can have endogenous function as integrin-mediated suppressors of pathologic angiogenesis and tumor growth.

Structural elucidation and antitumor activity of a fructan from Cyathula officinalis Kuan

A fructan named CoPS3 was isolated from Cyathula officinalis Kuan. The structure of CoPS3 was determined by methylation, by the reductive-cleavage method combined with GC-MS analysis, and both 1D and 2D 1H and 13C NMR spectroscopy. These results show that CoPS3 is a graminans-type fructan that is comprised of a beta-D-fructofuranosyl backbone having residues linked (2-->1)- and (2-->6) with branches and an alpha-D-glucopyranose residue on the nonreducing end of the fructan chain. Each branch is terminated by a beta-D-Fruf residue. Bioassay showed that it could inhibit growth of Lewis pulmonary carcinoma implanted in mice.

Dual Action of NAMI-A in inhibition of solid tumor metastasis: selective targeting of metastatic cells and binding to collagen

NAMI-A is a ruthenium complex endowed with a selective effect on lung metastases of solid metastasizing tumors. The aim of this study is to provide evidence that NAMI-A's effect is based on the selective sensitivity of the metastasis cell, as compared with other tumor cells, and to show that lungs represent a privileged site for the antimetastatic effects. The transplantation of Lewis lung carcinoma cells, harvested from the primary tumor of mice treated with 35 mg/kg/day NAMI-A for six consecutive days, a dose active on metastases, shows no change in primary tumor take and growth but a significant reduction in formation of spontaneous lung metastases. Transmission electron microscopy examination of lungs and kidney shows NAMI-A to selectively bind collagen of the lung extracellular matrix and also type IV collagen of the basement membrane of kidney glomeruli. The half lifetime of NAMI-A elimination from the lungs is longer than for liver, kidney, and primary tumor. NAMI-A bound to collagen is active on tumor cells as shown in vitro by an invasion test, using a modified Boyden chamber and Matrigel, and it inhibits the matrix metallo-proteinases MMP-2 and MMP-9 at micromolar concentrations, as shown in vitro by a zimography test. These data show NAMI-A to significantly affect tumor cells with metastatic ability. Binding to collagen allows NAMI-A to exert its selective activity on metastatic cells during dissemination and particularly in the lungs. These data also stress the wide spectrum of daily doses and treatment schedules at which NAMI-A is active against metastases.

Host prostaglandin E(2)-EP3 signaling regulates tumor-associated angiogenesis and tumor growth

Nonsteroidal antiinflammatories are known to suppress incidence and progression of malignancies including colorectal cancers. However, the precise mechanism of this action remains unknown. Using prostaglandin (PG) receptor knockout mice, we have evaluated a role of PGs in tumor-associated angiogenesis and tumor growth, and identified PG receptors involved. Sarcoma-180 cells implanted in wild-type (WT) mice formed a tumor with extensive angiogenesis, which was greatly suppressed by specific inhibitors for cyclooxygenase (COX)-2 but not for COX-1. Angiogenesis in sponge implantation model, which can mimic tumor-stromal angiogenesis, was markedly suppressed in mice lacking EP3 (EP3(-/-)) with reduced expression of vascular endothelial growth factor (VEGF) around the sponge implants. Further, implanted tumor growth (sarcoma-180, Lewis lung carcinoma) was markedly suppressed in EP3(-/-), in which tumor-associated angiogenesis was also reduced. Immunohistochemical analysis revealed that major VEGF-expressing cells in the stroma were CD3/Mac-1 double-negative fibroblasts, and that VEGF-expression in the stroma was markedly reduced in EP3(-/-), compared with WT. Application of an EP3 receptor antagonist inhibited tumor growth and angiogenesis in WT, but not in EP3(-/-). These results demonstrate significance of host stromal PGE(2)-EP3 receptor signaling in tumor development and angiogenesis. An EP3 receptor antagonist may be a candidate of chemopreventive agents effective for malignant tumors.

Wf-536 prevents tumor metastasis by inhibiting both tumor motility and angiogenic actions

The signaling pathway of Rho and Rho-associated coiled-coil forming protein kinase (ROCK) is involved in tumor metastasis. In the present study, we investigated the suppressive effect of a novel inhibitor of ROCK, Wf-536 [(+)-(R)-4-(1-Aminoethyl)-N-(4-pyridyl) benzamide monohydrochloride], on spontaneous tumor metastasis in vivo and analyzed its action on tumor cell motility and angiogenesis to clarify its action mechanism. Wf-536 (0.3-3 mg/kg/day) was found to inhibit Lewis lung carcinoma (LLC) metastasis and LLC-induced angiogenesis in orally treated mice; in vitro, it inhibited both invasion and migration by LLC cells and invasion, migration, and formation of capillary-like tubes on Matrigel by endothelial cells, without cytotoxicity or anti-proliferative action in either cell type. We conclude that Wf-536 has tumor anti-metastatic activity which may depend on inhibition of tumor motility and angiogenesis. The findings support its further clinical development as an anti-metastatic agent.