Macrophage cell-derived exosomes/staphylococcal enterotoxin B against fibrosarcoma tumor.

Targeted immune therapies are a modern approach to harness the immunity to treat cancer patients. Exosomes (EXOs) are nano-vesicles used for drug delivery in cancer treatment. We aimed to assess the effectiveness of novel designed EXO structures for immunotherapy alone and in combination with other components in animal models. EXO derived from untreated macrophage (EXO), WEHI-164 cell lysate treated EXO (EXOLys), HSP70 enriched WEHI-164 cell lysate treated EXO (EXOHSP70), Naloxone (NLX) treated EXO (EXONLX), Propranolol (PRP) treated EXO (EXOPRP) and staphylococcal enterotoxin B (SEB) anchored to three kinds of EXOs designated as EXO/SEB, EXOLys/SEB, EXOHSP70/SEB were purified from J774 cell line. To determine the therapeutic effect of these novel constructed nano-vesicles, the animals were immunized with different types of EXOs at weekly intervals for three consecutive weeks and in the fourth week the WEHI-164 tumor cells were injected. Finally, the splenocyte proliferation was examined by MTT assay and tumor growth was also determined in each group. We observed that EXOHSP was more effective than EXO and EXOLys to decrease the number of tumor cells and to stimulate immune responses in animal models (P < 0.05). In SEB-anchored EXO group, EXOHSP70/SEB has the potency to stimulate immune responses more efficiently than EXO/SEB and EXOLys/SEB and the tumor was not palpable until 28th day which may refer to synergistic effect of HSP70 and SEB on immunity. In EXONLX treated mice proliferative response decreased significantly compared to control group (P > 0.05) and the tumor number was constant within a period of 28 days and EXOPRP may delay the occurrence of the fibrosarcoma tumor; After development of fibrosarcoma the number of tumors diminished over the studied period of time. Our results demonstrate that HSP70 enriched EXO is an effective immunoadjuvant in cancer immunotherapy and causes tumor regression in animal model.

A longevity study with enhancer substances (selegiline, BPAP) detected an unknown tumor-manifestation-suppressing regulation in rat brain.

AIMS: First proof to show that (-)-deprenyl/selegiline (DEP), the first selective inhibitor of MAO-B, later identified as the first ß-phenylethylamine (PEA)-derived synthetic catecholaminergic activity enhancer (CAE) substance and (2R)-1-(1-benzofuran-2-yl)-N-propylpentane-2-amine (BPAP), the tryptamine-derived presently known most potent, selective, synthetic enhancer substance, are specific markers of unknown enhancer-sensitive brain regulations. MAIN METHODS: Longevity study disclosing the operation of tumor-manifestation-suppressing (TMS) regulation in rat brain. Immonohistochemical identification of a fibromyxosarcoma in rats. Experiments with human medulloblastoma cell lines. Analysis of the mechanism of action of enhancer substances. KEY FINDINGS: Whereas 20/40 saline-treated rats manifested a fibromyxosarcoma, in groups of rats treated with 0.001mg/kg DEP: 15/40 rats; with 0.1mg/kg DEP: 11/40 rats (P<0.01); with 0.0001mg/kg BPAP: 8/40 rats (P<0.001); with 0.05mg/kg BPAP: 7/40 rats (P<0.01) manifested the tumor. Experiments with human medulloblastoma cell lines, HTB-186 (Daoy); UW-228-2, showed that BPAP was devoid of direct cytotoxic effect on tumor cells, and did not alter the direct cytotoxic effectiveness of temozolomide, cisplatin, etoposide, or vincristine. Interaction with distinct sites on vesicular monoamine-transporter-2 (VMAT2) is the main mechanism of action of the enhancer substances which clarifies the highly characteristic bi-modal, bell-shaped concentration-effect curves of DEP and BPAP. SIGNIFICANCE: Considering of the safeness of the enhancer substances and the finding that DEP and BPAP, specific markers of unknown enhancer sensitive brain regulations, detected the operation of an enhancer-sensitive TMS-regulation in rat brain, it seems reasonable to test in humans low dose DEP or BPAP treatment against the spreading of a malignant tumor.

MULTIMERIN2 binds VEGF-A primarily via the carbohydrate chains exerting an angiostatic function and impairing tumor growth.

Angiogenesis is a key process occurring under both physiological and pathological conditions and is a hallmark of cancer. We have recently demonstrated that the extracellular matrix (ECM) molecule MULTIMERIN2 exerts an angiostatic function through the binding to VEGF-A. In this study we identify the region of the molecule responsible for the binding and demonstrate that the interaction involves the carbohydrate chains. MULTIMERIN2 interacts with other VEGF-A isoforms and VEGF family members such as VEGF-B, -C, -D and PlGF-1 suggesting that the molecule may function as a reservoir for different cytokines. In response to VEGF-A165, we show that MULTIMERIN2 impairs the phosphorylation of VEGFR2 at both Y1175 and Y1214 residues, halts SAPK2/p38 activation and negatively affects endothelial cell motility. In addition, MULTIMERIN2 and its active deletion mutant decrease the availability of the VEGFR2 receptor at the EC plasma membrane. The ectopic expression of MULTIMERIN2 or its active deletion mutant led to a striking reduction of tumor-associated angiogenesis and tumor growth. In conclusion, these data pinpoint MULTIMERIN2 as a key angiostatic molecule and disclose the possibility to develop new prognostic tools and improve the management of cancer patients.

Caffeine promotes anti-tumor immune response during tumor initiation: Involvement of the adenosine A2A receptor.

Epidemiologic studies depict a negative correlation between caffeine consumption and incidence of tumors in humans. The main pharmacological effects of caffeine are mediated by antagonism of the adenosine receptor, A2AR. Here, we examine whether the targeting of A2AR by caffeine plays a role in anti-tumor immunity. In particular, the effects of caffeine are studied in wild-type and A2AR knockout (A2AR(-/-)) mice. Tumor induction was achieved using the carcinogen 3-methylcholanthrene (3-MCA). Alternatively, tumor cells, comprised of 3-MCA-induced transformed cells or B16 melanoma cells, were inoculated into animal footpads. Cytokine release was determined in a mixed lymphocyte tumor reaction (MLTR). According to our findings, caffeine-consuming mice (0.1% in water) developed tumors at a lower rate compared to water-consuming mice (14% vs. 53%, respectively, p=0.0286, n=15/group). Within the caffeine-consuming mice, tumor-free mice displayed signs of autoimmune alopecia and pronounced leukocyte recruitment intocarcinogen injection sites. Similarly, A2AR(-/-) mice exhibited reduced rates of 3-MCA-induced tumors. In tumor inoculation studies, caffeine treatment resulted in inhibition of tumor growth and elevation in proinflammatory cytokine release over water-consuming mice, as depicted by MLTR. Addition of the adenosine receptor agonist, NECA, to MLTR resulted in a sharp decrease in IFNγ levels; this was reversed by the highly selective A2AR antagonist, ZM241385. Thus, immune response modulation through either caffeine or genetic deletion of A2AR leads to a Th1 immune profile and suppression of carcinogen-induced tumorigenesis. Taken together, our data suggest that the use of pharmacologic A2AR antagonists may hold therapeutic potential in diminishing the rate of cancer development.

NRP1 presented in trans to the endothelium arrests VEGFR2 endocytosis, preventing angiogenic signaling and tumor initiation.

Neuropilin 1 (NRP1) modulates angiogenesis by binding vascular endothelial growth factor (VEGF) and its receptor, VEGFR2. We examined the consequences when VEGFR2 and NRP1 were expressed on the same cell (cis) or on different cells (trans). In cis, VEGF induced rapid VEGFR2/NRP1 complex formation and internalization. In trans, complex formation was delayed and phosphorylation of phospholipase Cγ (PLCγ) and extracellular regulated kinase 2 (ERK2) was prolonged, whereas ERK1 phosphorylation was reduced. Trans complex formation suppressed initiation and vascularization of NRP1-expressing mouse fibrosarcoma and melanoma. Suppression in trans required high-affinity, steady-state binding of VEGF to NRP1, which was dependent on the NRP1 C-terminal domain. Compatible with a trans effect of NRP1, quiescent vasculature in the developing retina showed continuous high NRP1 expression, whereas angiogenic sprouting occurred where NRP1 levels fluctuated between adjacent endothelial cells. Therefore, through communication in trans, NRP1 can modulate VEGFR2 signaling and suppress angiogenesis.

The antibody-based targeted delivery of interleukin-4 and 12 to the tumor neovasculature eradicates tumors in three mouse models of cancer.

Preclinical studies with recombinant murine interleukin 4 (IL4) in models of cancer have shown potent tumor growth inhibition. However, systemic administration of human IL4 to cancer patients exhibited modest antitumor activity and considerable toxicities. To improve the therapeutic index and reduce side effects of this cytokine, we developed of a novel "immunocytokine" based on sequential fusion of murine IL4 with the antibody fragment F8 (specific to the alternatively spliced extra-domain A of fibronectin, a marker for tumor-angiogenesis) in diabody format. The resulting fusion protein, termed F8-IL4, retained full antigen-binding activity and cytokine bioactivity and was able to selectively localize on solid tumors in vivo. When used as single agent, F8-IL4 inhibited tumor growth in three different immunocompetent murine cancer models (F9 teratocarcinoma, CT26 colon carcinoma and A20 lymphoma). Furthermore, F8-IL4 showed synergistic effects when coadministered with immunocytokines based on IL2 and IL12. Indeed, combination therapy with an IL12-based immunocytokine yielded complete tumor eradication, in spite of the fact that IL4 and IL12 display opposite immunological mechanisms of action in terms of their polarization of T-cell based responses. No weight loss or any signs of toxicity were observed in treated mice, both in monotherapy and in combination, indicating a good tolerability of the immunocytokine treatment. Interestingly, mice cured from CT26 tumors acquired a durable protective antitumor immunity. Depletion experiments indicated that the antitumor activity was mediated by CD8+ T cells and by NK cells.

An analysis of factors related to recurrence of myxofibrosarcoma.

OBJECTIVE: Myxofibrosarcoma is clinically characterized by a high frequency of local recurrence after surgery. To improve the clinical outcome of patients with myxofibrosarcoma, it is imperative to control any postsurgical local recurrence. METHODS: In this study, we performed a retrospective clinicopathologic analysis of 100 consecutive patients with myxofibrosarcoma to identify factors related to poor prognosis. All of the patients had been diagnosed, and had undergone surgery at the National Cancer Center Hospital between 1999 and 2008. RESULTS: At the initial visit to our hospital, 64 patients had primary myxofibrosarcoma, whereas 36 had undergone primary unplanned resection at other facilities. Of the 36 patients, 11 consulted our hospital before recurrence and 25 did so after recurrence. A histologically positive margin after surgery was evident in 28% of the cases overall. The estimated 5-year recurrence-free survival rate was 74.8%. Univariate analysis showed that primary unplanned resection at another facility (P = 0.0001) and a histologically positive margin (P = 0.0224) were significant predictors of local recurrence. When these two factors were subjected to multivariate analysis, only primary unplanned resection at another facility was significantly correlated with the estimated recurrence-free survival rate (P = 0.0011). Primary unplanned resection was also significantly related to the 5-year disease-free survival rate (P = 0.0401). CONCLUSIONS: Our findings indicate that primary unplanned resection at a non-referral hospital is the most important risk factor related to poor prognosis of myxofibrosarcoma. Accurate diagnosis and adequate initial surgery are most important factors for improving the clinical outcomes of myxofibrosarcoma.

Adenoviral transduction of human acid sphingomyelinase into neo-angiogenic endothelium radiosensitizes tumor cure.

These studies define a new mechanism-based approach to radiosensitize tumor cure by single dose radiotherapy (SDRT). Published evidence indicates that SDRT induces acute microvascular endothelial apoptosis initiated via acid sphingomyelinase (ASMase) translocation to the external plasma membrane. Ensuing microvascular damage regulates radiation lethality of tumor stem cell clonogens to effect tumor cure. Based on this biology, we engineered an ASMase-producing vector consisting of a modified pre-proendothelin-1 promoter, PPE1(3x), and a hypoxia-inducible dual-binding HIF-2α-Ets-1 enhancer element upstream of the asmase gene, inserted into a replication-deficient adenovirus yielding the vector Ad5H2E-PPE1(3x)-ASMase. This vector confers ASMase over-expression in cycling angiogenic endothelium in vitro and within tumors in vivo, with no detectable enhancement in endothelium of normal tissues that exhibit a minute fraction of cycling cells or in non-endothelial tumor or normal tissue cells. Intravenous pretreatment with Ad5H2E-PPE1(3x)-ASMase markedly increases SDRT cure of inherently radiosensitive MCA/129 fibrosarcomas, and converts radiation-incurable B16 melanomas into biopsy-proven tumor cures. In contrast, Ad5H2E-PPE1(3x)-ASMase treatment did not impact radiation damage to small intestinal crypts as non-dividing small intestinal microvessels did not overexpress ASMase and were not radiosensitized. We posit that combination of genetic up-regulation of tumor microvascular ASMase and SDRT provides therapeutic options for currently radiation-incurable human tumors.

A cyanoacrylate and silastic patch to reduce the risk of opening of the tumor: technical note.

BACKGROUND: Wide surgery is the main factor influencing survival in muscular skeletal tumor. Sometimes the margin can be very thin and the contamination risk can be very high because of manipulation of the mass. MATERIALS AND METHODS: A patch of cyanoacrylate and a silastic mesh are applied on tumor surface. In order to demonstrate the tumor sealing an histologic exam was performed. DISCUSSION: The application of protective patch can decrease the risk of accidental tumor rupture and neoplastic cells spreading.

Chemopreventive property of Trichosanthes dioica root against 3-methylcholanthrene-induced carcinogenesis in albino mice.

This work reports the chemopreventive property of hydroalcoholic extract of the Trichosanthes dioica root (TDA) against 3-methylcholanthrene (3-MC)-induced carcinogenesis in Swiss albino mice. TDA was administered orally at 2 and 4 mg/kg for 45 days after 24 hours of a single subcutaneous administration of 3-MC (200 µg) in mice. The mice were observed for 15 weeks to record tumor incidence (fibrosarcoma) and survival. After 15 weeks the mice were killed for the evaluation of hematological profiles and hepatic biochemical parameters viz lipid peroxidation, reduced glutathione, glutathione-S-transferase, superoxide dismutase, and catalase. TDA treatment markedly reduced tumor incidence and prolonged the life span of sarcoma-bearing mice compared with 3-MC control mice. Hematological profiles of TDA-treated mice were restored significantly to normal levels. TDA treatment significantly modulated the liver biochemical parameters compared with 3-MC control. Therefore, TDA possesses remarkable cancer chemopreventive efficacy plausibly mediated by multiple mechanisms in Swiss albino mice.

Immunotherapy of tumors with α2-macroglobulin-antigen complexes pre-formed in vivo.

The cell surface receptor CD91/LRP-1 binds to immunogenic heat shock proteins (HSP) and α(2)M ligands to elicit T cell immune responses. In order to generate specific immune responses, the peptides chaperoned by HSPs or α(2)M are cross-presented on MHC molecules to T cells. While the immunogenic HSPs naturally chaperone peptides within cells and can be purified as an intact HSP-peptide complex, the peptides have had to be complexed artificially to α(2)M in previous studies. Here, we show that immunogenic α(2)M-peptide complexes can be isolated from the blood of tumor-bearing mice without further experimental manipulation in vitro demonstrating the natural association of tumor antigens with α(2)M. The naturally formed immunogenic α(2)M-peptide complexes are effective in prophylaxis and therapy of cancer in mouse models. We investigate the mechanisms of cross-presentation of associated peptides and co-stimulation by APCs that interact with α(2)M. These data have implications for vaccine design in immunotherapy of cancer and infectious disease.

Chemical sympathectomy suppresses fibrosarcoma development and improves survival of tumor-bearing rats.

Both experimental and clinical data indicate that the sympathetic nervous system may affect the development of certain tumors. To test this, in the present study we combined in vivo and in vitro approaches to study the effect of the sympathetic nervous system on proliferation of BP6-TU2 fibrosarcoma cells. First, we investigated the effect of 6-hydroxydopamine-induced sympathectomy on tumor development and survival of tumor-bearing rats. One week after chemical sympathectomy, we injected the BP6-TU2 fibrosarcoma cells intraperitoneally into male Wistar rats. The sympathectomy significantly reduced the incidence of intraperitoneal tumors and resulted in significantly improved survival of tumor-bearing rats compared to those with intact sympathetic innervation. Using immunohistochemical methods, we found neuron-specific enolase immunopositive structures within fibrosarcoma tissue, indicating innervation of tumors. Finally, an in vitro study showed elevated proliferation of BP6-TU2 fibrosarcoma cells in response to adding norepinephrine to the culture medium. Our findings indicate that sympathetic nerves directly potentiate the proliferation of BP6-TU2 fibrosarcoma cells in rats.

The development of a novel cancer immunotherapeutic platform using tumor-targeting mesenchymal stem cells and a protein vaccine.

An ideal anticancer strategy should target only the malignant cells but spare the normal ones. In this regard, we established a platform, consisting of an antigen-delivering vehicle and a protein vaccine, for developing an immunotherapeutic approach with the potential for eliminating various cancer types. Mesenchymal stem cells (MSCs) have been demonstrated capable of targeting tumors and integrating into the stroma. Moreover, we have developed a protein vaccine PE(ΔIII)-E7-KDEL3 which specifically recognized E7 antigen and elicited immunity against cervical cancer. Taking advantage of tumor-homing property of MSCs and PE(ΔIII)-E7-KDEL3, we used E6/E7-immortalized human MSCs (KP-hMSCs) as an E7 antigen-delivering vehicle to test if this protein vaccine could effectively eliminate non-E7-expressing tumor cells. Animals which received combined treatment of KP-hMSCs and PE(ΔIII)-E7-KDEL3 demonstrated a significant inhibition of tumor growth and lung-metastasis when compared to PE(ΔIII)-E7-KDEL3 only and KP-hMSCs only groups. The efficiency of tumor suppression correlated positively to the specific immune response induced by PE(ΔIII)-E7-KDEL3. In addition, this combined treatment inhibited tumor growth via inducing apoptosis. Our findings indicated that KP-hMSCs could be used as a tumor-targeting device and mediate antitumor effect of PE(ΔIII)-E7-KDEL3. We believe this strategy could serve as a platform for developing a universal vaccine for different cancer types.

In vivo anti- and pro-tumour activities of the TLR2 ligand FSL-1.

TLR ligands as Th1 inducers have been investigated as potential anti-tumour agents. However, few attempts have been made to investigate the anti-tumour activity of TLR ligands as Th2 inducers. This study, therefore, was carried out to determine whether the TLR2 ligand FSL-1 as a Th2 inducers affects the growth of a QRsP tumour, a fibrosarcoma derived from the C57BL/6 (TLR2(+/+)) mouse in vivo. Tumour volumes in TLR2(+/+) mice immunized with both FSL-1 and tumour-associated antigens were significantly smaller than those in control mice. Immunization with both FSL-1 and tumour-associated antigens increased the survival rate of TLR2(+/+) mice. However, surprisingly, immunization with FSL-1 alone significantly enhanced the growth of tumour. Both anti- and pro-tumour activities of FSL-1 were not observed in TLR2(-/-) mice. Immunization of both FSL-1 and tumour-associated antigens induced tumour-associated antigen-specific cytolytic T cells, antibody-dependent cell-mediated cytotoxicity of natural killer cells by production of the tumour-specific antibodies, tumour lysis by complement activation and reduction of the number of regulatory T cells in the draining lymph node. Immunization with FSL-1 alone increased the number of regulatory T cells in the draining lymph node, and in vivo administration of anti-CD25 antibody into mice abrogated the pro-tumour activity of FSL-1, suggesting that regulatory T cells are involved in the pro-tumour activity. This study demonstrated that FSL-1 exhibited TLR2-mediated anti- and pro-tumour activities when immunized with and without tumour-associated antigens, respectively.

Cancer preventive effect of Kumaizasa bamboo leaf extracts administered prior to carcinogenesis or cancer inoculation.

BACKGROUND: Kumaizasa bamboo found in Hokkaido is used for traditional medicine in Japan. The cancer preventive effect of vigorous (multistep) hot water extract of Kumaizasa was examined in relation to immunological conditioning and free radical scavenging activity. MATERIALS AND METHODS: Cytokine induction in mice, free radical scavenging activity in vitro, and cancer preventive effect by oral administration of the vigorous extracts prior to tumor implantation or carcinogenesis by 7,12-dimethylbenz[a]anthracene (DMBA) were examined. RESULTS: In tumor inoculated mouse models (S-180 sarcoma, Meth-A fibrosarcoma, B16-F10 melanoma), the vigorous extracts from Kumaizasa bamboo leaves suppressed tumor growth and prolonged survival significantly. In the chemical carcinogenesis model suppression of cancer incidence on day 100, tumor size and survival time were significantly improved with the vigorous extract, at/or above 0.03% in the diet, when given two weeks prior to the administration of the carcinogen. CONCLUSION: The vigorous extracts of bamboo leaf show immunopotentiating and radical scavenging effects and administration prior to carcinogen exposure or tumor inoculation significantly suppresses tumor incidence and tumor growth and prolongs survival.

Dendritic cell-based immunotherapy induces transient clinical response in advanced rat fibrosarcoma - comparison with preventive anti-tumour vaccination.

In this study we present the models of preventive and therapeutic vaccination of sarcoma-bearing rats with dendritic cells that present tumour antigens from killed tumour cells. We present the characteristics of dendritic cell-based vaccine and its capacity to induce anti-tumour immune response both in vitro and in vivo. We show that preventive vaccination efficiently prevents tumour growth. On the other hand, vaccination of rats with established tumours did not lead to eradication of the tumours. Despite the induction of a vigorous immune response after administration of dendritic cell-based vaccine and transient decrease in tumour progression, tumours eventually resumed their growth and animals vaccinated with dendritic cells succumbed to cancer. In both settings, preventive and therapeutic, dendritic cell-based vaccination induced a vigorous tumour-specific T-cell response. These results argue for the timing of cancer immunotherapy to the stages of low tumour load. Immunotherapy initiated at the stage of minimal residual disease, after reduction of tumour load by other modalities, will have much better chance to offer a clinical benefit to cancer patients than the immunotherapy at the stage of metastatic disease.

Effects of Toxoplasma gondii and Toxocara canis antigens on WEHI-164 fibrosarcoma growth in a mouse model.

Cancer is the main cause of death in developed countries. However, in underdeveloped countries infections and parasitic diseases are the main causes of death. There are raising scientific evidences indicating that parasitic infections induce antitumor activity against certain types of cancers. In this study, the effects of Toxoplasma gondii and Toxocara canis egg antigens in comparison with Bacillus Calmette Guerin (BCG) (known to have anticancer distinctive) on WEHI-164 fibosarcoma transplanted to BALB/c mice was investigated. Groups of 6 male BALB/c mice injected with T. gondii antigen, BCG, or T. canis egg antigen as case groups and alum alone as control groups. All mice were then challenged with WEHI-164 fibrosarcoma cells. The mice were examined for growth of the solid tumor and the tumor sizes were measured every other day up to 4 wk. The mean tumor area in T. gondii, BCG, or alum alone injected mice in 4 different days of measurements was 25 mm(2), 23 mm(2), and 186 mm(2) respectively. Also the mean tumor area in T. canis injected mice in 4 different days was 25.5 mm(2) compared to the control group (alum treated) which was 155 mm(2). T. gondii parasites and T. canis egg antigens induced inhibition of the tumor growth in the fibrosarcoma mouse model. We need further study to clarify the mechanisms of anti-cancer effects.

Limited role of murine ATM in oncogene-induced senescence and p53-dependent tumor suppression.

Recent studies in human fibroblasts have provided a new general paradigm of tumor suppression according to which oncogenic signaling produces DNA damage and this, in turn, results in ATM/p53-dependent cellular senescence. Here, we have tested this model in a variety of murine experimental systems. Overexpression of oncogenic Ras in murine fibroblasts efficiently induced senescence but this occurred in the absence of detectable DNA damage signaling, thus suggesting a fundamental difference between human and murine cells. Moreover, lung adenomas initiated by endogenous levels of oncogenic K-Ras presented abundant senescent cells, but undetectable DNA damage signaling. Accordingly, K-Ras-driven adenomas were also senescent in Atm-null mice, and the tumorigenic progression of these lesions was only modestly accelerated by Atm-deficiency. Finally, we have examined chemically-induced fibrosarcomas, which possess a persistently activated DNA damage response and are highly sensitive to the activity of p53. We found that the absence of Atm favored genomic instability in the resulting tumors, but did not affect the persistent DNA damage response and did not impair p53-dependent tumor suppression. All together, we conclude that oncogene-induced senescence in mice may occur in the absence of a detectable DNA damage response. Regarding murine Atm, our data suggest that it plays a minor role in oncogene-induced senescence or in p53-dependent tumor suppression, being its tumor suppressive activity probably limited to the maintenance of genomic stability.

Restoration of tumor immunosurveillance via targeting of interleukin-13 receptor-alpha 2.

In previous studies, we described a "counter-immunosurveillance" mechanism initiated by tumor-activated, interleukin-13 (IL-13)-producing natural killer T cells that signal Gr-1(+) cells to produce transforming growth factor-beta(1) (TGF-beta(1)), a cytokine that suppresses the activity of tumor-inhibiting cytolytic CD8(+) T cells. Here, we show that in two tumor models (the CT-26 metastatic colon cancer and the 15-12RM fibrosarcoma regressor models), this counter-surveillance mechanism requires the expression of a novel IL-13 receptor, IL-13R alpha(2), on Gr-1(intermediate) cells, because down-regulation of IL-13R alpha(2) expression or the activator protein-1 signal generated by the receptor via in vivo administration of specific small interfering RNA or decoy oligonucleotides leads to loss of TGF-beta(1) production. Furthermore, acting on prior studies showing that IL-13R alpha(2) expression is induced (in part) by tumor necrosis factor-alpha (TNF-alpha), we show that receptor expression and TGF-beta(1) production is inhibited by administration of a TNF-alpha-neutralizing substance, TNF-alpha R-Fc (etanercept). Taking advantage of this latter fact, we then show in the CT-26 model that counter-immunosurveillance can be inhibited, anti-CT-26-specific CD8(+) cytolytic activity can be restored, and CT-26 metastatic tumor nodules can be greatly decreased by administration of TNF-alpha R-Fc. Corroborative data were obtained using the 15-12RM fibrosarcoma model. These studies point to the prevention of metastatic cancer with an available agent with already known clinically acceptable adverse effects and toxicity.

Immune gene therapy as a neoadjuvant to surgical excision to control metastatic cancers.

We investigated if the range of efficacy of a gene-based immunotherapy of solid tumours against systemic disease could be extended when used as a neoadjuvant to surgery. Hundred percent mice whose subcutaneous tumours were surgically removed 4 days post-electroporation with GM-CSF and B7-1 plasmid were systemically resistance to tumour rechallenge. In mice bearing both subcutaneous and hepatic tumours, neoadjuvant treatment of the primary tumour resulted in significant reduction in, or elimination of, hepatic tumour growth, with a significant increase in survival, indicating that control of the primary tumour by immunotherapy was not a prerequisite for containment of systemic disease.