Pre-treatment with Bifidobacterium infantis and its specific antibodies enhance targeted radiosensitization in a murine model for lung cancer.

PURPOSE: The hypoxic microenvironments of solid tumours are complex and reduce the susceptibility of cancer cells to chemo- and radiotherapy. Conventional radiosensitisers have poor specificity, unsatisfactory therapeutic effects, and significant side effects. Anaerobic bacteria colonise and destroy hypoxic areas of the tumour and consequently enhance the effects of radiation. METHODS: In this study, we treated a Lewis lung carcinoma transplant mouse model with Bifidobacterium infantis (Bi) combined with its specific monoclonal antibody (mAb) and radiotherapy (RT) to investigate its ability to radiosensitise the tumour. The tumour metabolism and hypoxia in the tumour tissue were monitored by micro-18F-FDG and 18F-FMISO PET/CT imaging. Immunohistochemistry was used to detect phosphorylated histone (γ-H2AX), proliferation (Ki-67), platelet endothelial cell adhesion molecules (CD31), tumour necrosis factor-α (TNF-α), hypoxia-inducible factor-1α (HIF-1α), and glucose transporter 1 (Glut-1) levels. RESULTS: Tumour growth was slowed and survival time was markedly prolonged in mice subjected to the combination of B. infantis, specific antibody, and radiotherapy. Levels of HIF-1α, Glut-1, Ki-67, and CD31 expression, as well as uptake of FDG and FMISO, were the lowest in the combination-treated mice. In contrast, γ-H2AX and TNF-α expression levels were elevated and hypoxia in tumour tissue was reduced compared with controls. CONCLUSION: In conclusion, our data indicated that the curative effect of radiotherapy for lung cancer was enhanced by pre-treating mice with a combination of B. infantis and its specific monoclonal antibody.

Toll-Like Receptor-4 Disruption Suppresses Adipose Tissue Remodeling and Increases Survival in Cancer Cachexia Syndrome.

Cancer-induced cachexia, characterized by systemic inflammation, body weight loss, adipose tissue (AT) remodeling and muscle wasting, is a malignant metabolic syndrome with undefined etiology. Here, we show that both genetic ablation and pharmacological inhibition of TLR4 were able to attenuate the main clinical markers of cachexia in mice bearing Lewis lung carcinoma (LLC). AT remodelling was not found in LLC tumor-bearing (TB) TLR4-/- mice due to reduced macrophage infiltration and adipocyte atrophy. TLR4-/- mice were also resistant to cold-induced browning of subcutaneous AT (scAT). Importantly, pharmacological inhibition of TLR4 (Atorvastatin) reproduced the main protective effect against AT remodeling found in TLR4-/- TB mice. Moreover, the treatment was effective in prolonging survival and attenuating tumor mass growth when compared to non-treated-TB animals. Furthermore, tumor-induced elevation of circulating pro-inflammatory cytokines was similarly abolished in both genetic ablation and pharmacological inhibition of TLR4. These data suggest that TLR4 is a critical mediator and a promising target for novel anti-cachexia therapies.

A novel pathway of LPS uptake through syndecan-1 leading to pyroptotic cell death.

Intracellular lipopolysaccharide (LPS) triggers the non-canonical inflammasome pathway, resulting in pyroptosis of innate immune cells. In addition to its well-known proinflammatory role, LPS can directly cause regression of some tumors, although the underlying mechanism has remained unknown. Here we show that secretoglobin(SCGB)3A2, a small protein predominantly secreted in airways, chaperones LPS to the cytosol through the cell surface receptor syndecan-1; this leads to pyroptotic cell death driven by caspase-11. SCGB3A2 and LPS co-treatment significantly induced pyroptosis of macrophage RAW264.7 cells and decreased cancer cell proliferation in vitro, while SCGB3A2 treatment resulted in reduced progression of xenograft tumors in mice. These data suggest a conserved function for SCGB3A2 in the innate immune system and cancer cells. These findings demonstrate a critical role for SCGB3A2 as an LPS delivery vehicle; they reveal one mechanism whereby LPS enters innate immune cells leading to pyroptosis, and they clarify the direct effect of LPS on cancer cells.

Disulfide-cross-linked PEG-block-polypeptide nanoparticles with high drug loading content as glutathione-triggered anticancer drug nanocarriers.

The development of stimuli-responsive drug carrier systems enabling to deliver high doses of anti-cancer drugs to tumor tissues is still urgently needed. In this study, we report the preparation of reduction-responsive methoxypolyethylene glycol-block-(poly(l-lysine)-co-poly(l-tyrosine)) (mPEG-b-(PLL-co-PLY)) nanoparticles (NPs) exhibiting sizes smaller than 100 nm and high drug loading content (DLC) of doxorubicin (DOX) by selecting the Lys and Tyr residues as the polypeptide building blocks. The disulfide-cross-linked mPEG-b-(PLL-co-PLY) assemblies with sizes can be tuned by varying the polypeptide composition followed by subsequent disulfide-cross-linking. Cytotoxicity assays showed that the Dox-loaded NPs exhibited efficient cell internalization and proliferation inhibition toward cancer cells, whereas the copolymers exhibited low hemolysis to human red blood cells and excellent biocompatibility to both normal and cancer cells. The enhanced internalization and cytotoxicity of DOX-NPs can be possible due to their small size and their reduction-responsive property. Anticancer studies using C57BL/6 mice bearing LLC tumor model showed that the DOX-loaded NPs significantly suppressed tumor growth and prolonged the survival of tumor-bearing mice without obvious body weight loss and damage to major organs. This approach provides a platform for developing stimuli-responsive, polypeptide-based drug delivery systems with high DLC for cancer treatment.

Bacterial ghosts as adjuvants in syngeneic tumour cell lysate-based anticancer vaccination in a murine lung carcinoma model.

Instead of relying on external anticancer factors for treatment, immunotherapy utilizes the host's own immune system and directs it against given tumour antigens. This study demonstrated that it is possible to overcome the documented immunosuppressive properties of tumour cell lysate by supplementing it with appropriate adjuvant. Lewis lung carcinoma (LLC)­challenged C57BL/6 mice were treated with LLC cryo­lysate mixed with either bacterial ghosts (BGs) generated from E. coli Nissle 1917 or B. subtilis 70 kDa protein as adjuvants. Median and overall survival, the size of metastatic foci in lung tissue and levels of circulating CD8a+ T cells were evaluated and compared to the untreated control mice or mice treated with LLC lysate alone. After primary tumour removal, a course of three subcutaneous vaccinations with LLC lysate supplemented with BGs led to a significant increase in overall survival (80% after 84 days of follow­up vs. 40% in untreated control mice), a significant increase in circulating CD8a+ T cells (16.57 vs. 12.6% in untreated control mice) and a significant decrease in metastasis foci area and incidence. LLC lysate supplemented with B. subtilis protein also improved the inspected parameters in the treated mice, when compared against the untreated control mice, but not to a significant degree. Therefore, whole cell lysate supplemented with BGs emerges as an immunostimulatory construct with potential clinical applications in cancer treatment.

Optimized magnitude of cryosurgery facilitating anti-tumor immunoreaction in a mouse model of Lewis lung cancer.

BACKGROUND: Cryosurgery has reemerged as a less invasive local treatment with possible immune-regulatory effects. However, the optimal magnitude of cryosurgery for achieving immune-regulatory responses at abscopal tumor sites remains unclear. We aimed to investigate appropriate magnitude of cryosurgery for this goal using a mouse model. METHODS: C57BL/6J mice were inoculated with Lewis lung carcinoma cells or B16 melanoma cells in bilateral flanks. The left-sided tumor was cryoablated with repeated freeze/thaw cycles either once, twice, or thrice. The peritumoral injections of LPS were performed. Abscopal tumor volumes were measured, immunohistochemistry was performed for CD4, CD8, Foxp3, and Ki-67, and proinflammatory cytokines were measured in lavage fluid of cryoablated tumor. RESULTS: The growth rate of the abscopal tumor was slowest in the Cryosurgery ×2 group among the five experimental groups. The proportions of CD4(+) T cells and CD8(+) T cells in the abscopal tumor were also significantly higher in the Cryosurgery ×2 group. The levels of IL-1ß, IL-2, IL-6, IL-12ß, IFN-γ, and TNF-α in the peritumoral lavage fluid in Cryosurgery ×2 + LPS group were significantly increased compared with the other groups. CONCLUSIONS: This study suggested that achievement of approximately 73 % damaged area in the cryoablated tumor by two cycles of cryosurgery generates the most favorable immune-regulatory response for abscopal tumors via activation of anti-tumor immune cells as well as increased secretion of proinflammatory cytokines.

Thymosin α1 promotes the activation of myeloid-derived suppressor cells in a Lewis lung cancer model by upregulating Arginase 1.

Thymosin α1 (Tα1) has been tested for cancer therapy for several years, in most cases, the anti-tumor effect of Tα1 was limited, especially when Tα1 was used as a single agent. The role of Tα1 in cancer treatment and the regulatory mechanisms by which Ta1 takes effects are not yet completely understood. Using a Lewis lung caner model, here we report that Tα1 used alone elevated CD8(+) T cells, but failed to inhibit tumor growth. Furthermore, immunosuppressive myeloid-derived suppressor cells (MDSCs) showed heightened Arginase 1 production in response to Tα1 treatment, which led to stronger suppression of anti-tumor immunity. In addition, the upregulation of ARG1 was dependent on TLRs/MyD88 signaling, blocking MyD88 signaling abrogated the enhanced ARG1 expression and restored the anti-tumor efficacy of Tα1. This study provides the first demonstration that Tα1 treatment activates but not expands MDSCs via MyD88 signaling, which indicates better immunotherapeutic strategy of Tα1 against cancer.

Enhanced dendritic cell-based immunotherapy using low-dose cyclophosphamide and CD25-targeted antibody for transplanted Lewis lung carcinoma cells.

Regulatory T cells (Tregs) is one of the main obstacles to the success of cancer immunotherapy. The effect of dendritic cell (DC)-based immunotherapy can be attenuated by immune suppressive functions of Tregs. We used a CD25-targeted antibody and low-dose cyclophosphamide (CTX) as immunomodulators to increase the antitumor effect of intratumoral injection of immature DCs into the irradiated tumor cells (IR/iDC). CTX or CD25-targeted antibody alone showed a significant reduction in the number of Tregs within the tumor microenvironment. When they are combined with IR/iDC, the number of Tregs was further reduced. Although IR/IDC showed strong antitumor effects such as reduction in tumor growth, increase in Th1 immune response, and improvement of survival, the therapeutic effect was further improved by combining treatments with immunomodulators. CTX and CD25-targeted antibody showed no significant difference in tumor growth when combined with IR/iDC, but CTX further increased the number of interferon (IFN)-γ-secreting T cells, cytotoxicity, and survival rate. Although irradiation induced depletion of T lymphocytes, administration of DCs recovered this depletion. Particularly, the lymphocytes were more significantly increased when CTX and IR/iDC were combined. Low-dose CTX has already been used as an immunomodulator in clinical trials, and it offers several advantages, including convenience, low-cost, and familiarity to clinicians. However, CD25-targeted antibody cannot only deplete Tregs, but also may affect IL-2-dependent effector T lymphocytes. Therefore, CTX is an effective means to inhibit Tregs, and an effective immunomodulatory agent for multimodality therapy such as combination treatment of conventional cancer therapy and immunotherapy.

Anti-CD40-induced inflammatory E-cadherin+ dendritic cells enhance T cell responses and antitumour immunity in murine Lewis lung carcinoma.

BACKGROUND: Agonistic CD40 antibodies have been demonstrated to activate antigen-presenting cells (APCs) and enhance antitumour T cell responses, thereby providing a new therapeutic option in cancer immunotherapy. In agonistic CD40 antibody-mediated inflammatory responses, a novel subset of E-cadherin + dendritic cells (DCs) has been identified, and little is known about the role of these DCs in tumour immunity. This study investigated the effect of anti-CD40-mediated inflammatory E-cadherin + DCs in murine Lewis lung carcinoma (LLC). METHODS: The phenotype and characteristics of anti-CD40-mediated inflammatory E-cadherin + DCs isolated from the anti-CD40 model were assessed in vitro. The antitumour activity of E-cadherin + DCs were evaluated in vivo by promoting the differentiation of effector CD4+ T cells, CEA-specific CD8+ T cells and CD103+ CD8+ T cells and assessing their resistance to tumour challenge, including variations in tumour volume and survival curves. RESULTS: Here, we demonstrated that anti-CD40-mediated E-cadherin + inflammatory DCs accumulate in the lungs of Rag1 KO mice and were able to stimulate naïve CD4+ T cells to induce Th1 and Th17 cell differentiation and polarisation and to inhibit regulatory T cell and Th2 responses. Importantly, with the adoptive transfer of E-cadherin + DCs into the Lewis lung cancer model, the inflammatory DCs increased the Th1 and Th17 cell responses and reduced the Treg cell and Th2 responses. Interestingly, following the injection of inflammatory E-cadherin + DCs, the CD103+ CD8+ T cell and CEA-specific CD8+ T cell responses increased and exhibited potent antitumour immunity. CONCLUSIONS: These findings indicate that anti-CD40-induced E-cadherin + DCs enhance T cell responses and antitumour activity in non-small cell lung cancer (NSCLC)-bearing mice and may be used to enhance the efficacy of DC-based peptide vaccines against NSCLC.

Alternating electric fields (tumor-treating fields therapy) can improve chemotherapy treatment efficacy in non-small cell lung cancer both in vitro and in vivo.

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-related deaths worldwide. Common treatment modalities for NSCLC include surgery, radiotherapy, chemotherapy, and, in recent years, the clinical management paradigm has evolved with the advent of targeted therapies. Despite such advances, the impact of systemic therapies for advanced disease remains modest, and as such, the prognosis for patients with NSCLC remains poor. Standard modalities are not without their respective toxicities and there is a clear need to improve both efficacy and safety for current management approaches. Tumor-treating fields (TTFields) are low-intensity, intermediate-frequency alternating electric fields that disrupt proper spindle microtubule arrangement, thereby leading to mitotic arrest and ultimately to cell death. We evaluated the effects of combining TTFields with standard chemotherapeutic agents on several NSCLC cell lines, both in vitro and in vivo. Frequency titration curves demonstrated that the inhibitory effects of TTFields were maximal at 150 kHz for all NSCLC cell lines tested, and that the addition of TTFields to chemotherapy resulted in enhanced treatment efficacy across all cell lines. We investigated the response of Lewis lung carcinoma and KLN205 squamous cell carcinoma in mice treated with TTFields in combination with pemetrexed, cisplatin, or paclitaxel and compared these to the efficacy observed in mice exposed only to the single agents. Combining TTFields with these therapeutic agents enhanced treatment efficacy in comparison with the respective single agents and control groups in all animal models. Together, these findings suggest that combining TTFields therapy with chemotherapy may provide an additive efficacy benefit in the management of NSCLC.

Superior anti-tumor protection and therapeutic efficacy of vaccination with dendritic cell/tumor cell fusion hybrids for murine Lewis lung carcinoma.

BACKGROUND: The development of protocols for the ex vivo generation of dendritic cells (DCs) has led to intensive research into their potential use in immunotherapy in the treatment of cancer. In this study, we examined the efficacy of dendritic cell-tumor cell fusion hybrid vaccines in eliciting an immune response against Lewis lung carcinoma (LLC) cells, as compared to other types of tumor vaccines. In addition, we also tested whether the efficacy of the vaccines was affected by the route of administration. Four different tumor vaccines were compared: (1) HC (hybrid cell), consisting of DC/LLC hybrids; (2) DC+LLC (DCs pulsed with apoptotic LLCs); (3) DC without antigen loading/pulsing; (4) LLC (apoptotic/irradiated tumor cells). We also compared four different routes of administration for each vaccine: (1) Preimmunization; (2) Vaccination therapy; (3) Adoptive immunotherapy; (4) Vaccination therapy combined with adoptive immunotherapy. Anti-tumor immunity was assessed in vivo and the CTL (cytotoxic T lymphocyte) response as well as the expression of key cytokines, IFN-γ and IL-10 were further evaluated using in vitro assays. RESULTS: Our data demonstrate that vaccination with HC hybrids provides more effective anti-tumor protective immunity and significantly greater therapeutic immunity than vaccination with DC+LLC, DC or LLC. Most remarkably, vaccination therapy with HC hybrids was more successful than combination (vaccination + adoptive) therapy for the induction of anti-tumor responses. Splenocytes harvested from mice immunized with HC hybrids demonstrated the greatest cytotoxic T lymphocyte (CTL) activity and their production of IFN-γ was high, while their production of IL-10 was very low. CONCLUSIONS: Our results suggest that vaccination therapy with DC-tumor cell fusion hybrids provides more effective protection against lung cancer.

HPMA copolymer conjugates of DOX and mitomycin C for combination therapy: physicochemical characterization, cytotoxic effects, combination index analysis, and anti-tumor efficacy.

The synthesis, characterization and results of evaluation of the biological behavior of HPMA copolymer conjugates bearing anti-cancer drugs doxorubicin and mitomycin C are described. Two HPMA copolymer carrier types were synthesized: the linear copolymer and the biodegradable high-molecular-weight diblock copolymer containing a degradable disulfide bond. The polymer-drug conjugates incubated in buffers modeling the intracellular environment released the drugs more rapidly than those incubated in bloodstream conditions. Significant in vitro and in vivo antitumor synergistic activity of the conjugates in the treatment of EL-4 T-cell demonstrates their high potential for solid tumor treatment.

Endostar combined with cisplatin inhibits tumor growth and lymphatic metastasis of lewis lung carcinoma xenografts in mice.

OBJECTIVE: To investigate the effects of endostar, a recombined humanized endostatin, plus cisplatin on the growth, lymphangiogenesis and lymphatic metastasis of the Lewis lung carcinoma (LLC) in mice. METHODS: A tumor model were established in C57BL/6 mice by intravenious transplantation of LLC cells. Then the mice were randomized to receive administration with NS, endostar, cisplatin, or endostar plus cisplatin. After the mice were sacrificed, tumor multiplicity, tumor size and lymph node metastasis were assessed. Then the expression of vascular endothelial growth factor-c (VEGF-C) and podoplanin were determined by immunohistochemical staining. RESULTS: Endostar plus cisplatin significantly suppressed tumor growth. lymphatic metastasis and prolonged survival time of the mice without obvious toxicity. The inhibition of lymphatic metastasis was associated with decreased microlymphatic vessel density (MLVD) and expression of VEGF-C. CONCLUSIONS: Endostar combined with cisplatin was more effective to suppress tumor growth and lymphatic metastasis than either agent alone. Thus this may provide a rational alternative for lung carcinoma treatment.

Synergistic effect of CTLA-4 blockade and cancer chemotherapy in the induction of anti-tumor immunity.

Several chemotherapeutics exert immunomodulatory effects. One of these is the nucleoside analogue gemcitabine, which is widely used in patients with lung cancer, ovarian cancer, breast cancer, mesothelioma and several other types of cancer, but with limited efficacy. We hypothesized that the immunopotentiating effects of this drug are partly restrained by the inhibitory T cell molecule CTLA-4 and thus could be augmented by combining it with a blocking antibody against CTLA-4, which on its own has recently shown beneficial clinical effects in the treatment of patients with metastatic melanoma. Here we show, using two non-immunogenic murine tumor models, that treatment with gemcitabine chemotherapy in combination with CTLA-4 blockade results in the induction of a potent anti-tumor immune response. Depletion experiments demonstrated that both CD4(+) and CD8(+) T cells are required for optimal therapeutic effect. Mice treated with the combination exhibited tumor regression and long-term protective immunity. In addition, we show that the efficacy of the combination is moderated by the timing of administration of the two agents. Our results show that immune checkpoint blockade and cytotoxic chemotherapy can have a synergistic effect in the treatment of cancer. These results provide a basis to pursue combination therapies with anti-CTLA-4 and immunopotentiating chemotherapy and have important implications for future studies in cancer patients. Since both drugs are approved for use in patients our data can be immediately translated into clinical trials.

Cell surface receptor FPR2 promotes antitumor host defense by limiting M2 polarization of macrophages.

FPR2 (Fpr2 in mouse) is a G-protein-coupled receptor interacting with bacterial and host-derived chemotactic agonists. Fpr2 supports innate and adaptive immune responses as illustrated by the reduction in severity of allergic airway inflammation in Fpr2-KO mice, due to impaired trafficking of antigen-presenting dendritic cells (DC). The aim of this study is to examine the role of Fpr2 in host antitumor responses. We found that Fpr2-KO mice bearing subcutaneously implanted Lewis lung carcinoma (LLC) cells exhibited significantly shortened survival than normal mice due to more rapidly growing tumors. In contrast, in Fpr2-transgenic mice overexpressing Fpr2, subcutaneously implanted LLC tumors grew more slowly than those in wild-type (WT) littermates. Investigation of tumor tissues revealed an increased number of macrophages associated with tumors grown in Fpr2-KO mice. Macrophages derived from Fpr2-KO mice showed a more potent chemotactic response to LLC-derived supernatant (LLC Sup), which could be neutralized by an anti-CCL2 antibody. The increased chemotaxis of Fpr2-KO mouse macrophages in response to LLC Sup was due to their higher level expression of CCR4, a chemokine receptor that also recognizes the ligand CCL2. Furthermore, macrophages from Fpr2-KO mice acquired an M2 phenotype after stimulation with LLC Sup. These results suggest that Fpr2 plays an important role in host defense against implanted LLC by sustaining macrophages in an M1 phenotype with more potent antitumor activities.

Inhibitory effect of Bifidobacterium infantis-mediated sKDR prokaryotic expression system on angiogenesis and growth of Lewis lung cancer in mice.

BACKGROUND: To construct the Bifidobacterium infantis-mediated soluble kinase insert domain receptor (sKDR) prokaryotic expression system and to observe its inhibitory effect on growth of human umbilicus vessel endothelial cells (HUVECs) in vitro and Lewis lung cancer (LLC) on mice in vivo. METHODS: The Bifidobacterium infantis-mediated sKDR prokaryotic expression system was constructed through electroporation and subsequently identified through PCR and Western blot analysis. HUVECs were added to the products of this system to evaluate the anti-angiogenesis effect through MTT assay in vitro. The LLC mice models were divided into three groups: one group treated with saline (group a); one group treated with recombinant Bifidobacterium infantis containing pTRKH2-PsT plasmid group (group b); and one group treated with recombinant Bifidobacterium infantis containing pTRKH2-PsT/sKDR plasmid group (group c). The quality of life and survival of mice were recorded. Tumor volume, tumor weight, inhibitive rate, and necrosis rate of tumor were also evaluated. Necrosis of tumor and signals of blood flow in tumors were detected through color Doppler ultrasound. In addition, microvessel density (MVD) of the tumor tissues was assessed through CD31 immunohistochemical analysis. RESULTS: The positively transformed Bifidobacterium infantis with recombinant pTRKH2-PsT/sKDR plasmid was established, and was able to express sKDR at gene and protein levels. The proliferation of HUVECs cultivated with the extract of positively transformed bacteria was inhibited significantly compared with other groups (P < 0. 05). The quality of life of mice in group c was better than in group a and b. The recombinant Bifidobacterium infantis containing pTRKH2-PsT/sKDR plasmid enhanced the efficacy of tumor growth suppression and prolongation of survival, increased the necrosis rate of tumor significantly, and could obviously decrease MVD and the signals of blood flow in tumors. CONCLUSION: The Bifidobacterium infantis-mediated sKDR prokaryotic expression system was constructed successfully. This system could express sKDR at gene and protein levels and significantly inhibit the growth of HUVECs induced by VEGF in vitro. Moreover, it could inhibit tumor growth and safely prolong the survival time of LLC C57BL/6 mice.

Endoplasmic reticulum chaperone glucose regulated protein 170-Pokemon complexes elicit a robust antitumor immune response in vivo.

Previous evidence suggested that the stress protein grp170 can function as a highly efficient molecular chaperone, binding to large protein substrates and acting as a potent vaccine against specific tumors when purified from the same tumor. In addition, Pokemon can be found in almost all malignant tumor cells and is regarded to be a promising candidate for the treatment of tumors. However, the potential of the grp170-Pokemon chaperone complex has not been well described. In the present study, the natural chaperone complex between grp170 and the Pokemon was formed by heat shock, and its immunogenicity was detected by ELISPOT and (51)Cr-release assays in vitro and by tumor bearing models in vivo. Our results demonstrated that the grp170-Pokemon chaperone complex could elicit T cell responses as determined by ELISPOT and (51)Cr-release assays. In addition, immunized C57BL/6 mice were challenged with subcutaneous (s.c.) injection of Lewis cancer cells to induce primary tumors. Treatment of mice with the grp170-Pokemon chaperone complex also significantly inhibited tumor growth and prolonged the life span of tumor-bearing mice. Our results indicated that the grp170-Pokemon chaperone complex might represent a powerful approach to tumor immunotherapy and have significant potential for clinical application.

Efficacy against lung metastasis with a tumor-targeting mutant of Salmonella typhimurium in immunocompetent mice.

Salmonella typhimurium double leu-arg auxotrophs have been shown to be highly effective as antitumor agents in nude mouse models of human metastatic cancer. In order to proceed to clinical development of the S. typhimurium double auxotroph, termed A1-R, it is necessary to evaluate antitumor efficacy in immunocompetent mice. In the present study, we have observed the efficacy of A1-R on the Lewis lung (LLC) carcinoma in vitro as well as in C57BL/6 (C57) immunocompetent mice. In vitro, A1-R treatment of LLC began to induce cell death within one hour. Various doses and schedules of A1-R were administered to C57 mice implanted with LLC, including bolus single intravenous injection; medium dose with weekly intravenous administration and metronomic treatment with small intravenous doses twice a week. Bolus treatment was toxic to the immunocompetent host, in contrast to nude mice. Lower-dose weekly doses and metronomic doses were well tolerated by the immunocompetent host. Weekly intravenous injection with 2 × 10(7) bacteria and twice a week intravenous injection with 10(7) bacteria significantly inhibited metastasis formation, while bolus injection was toxic. Intra-thoracic administration was carried out with 10(8) bacteria A1-R injected into Lewis lung-bearing C57 mice weekly for three weeks. Lung metastasis was significantly inhibited by intrathoracic bacterial administration, without toxicity. The results in this report, demonstrating the anti-metastatic efficacy of S. typhimurium A1-R in immunocompetent mice, indicate the clinical potential of bacterial therapy of cancer.

The in vivo study on the radiobiologic effect of prolonged delivery time to tumor control in C57BL mice implanted with Lewis lung cancer.

BACKGROUND: High-precision radiation therapy techniques such as IMRT or sterotactic radiosurgery, delivers more complex treatment fields than conventional techniques. The increased complexity causes longer dose delivery times for each fraction. The purpose of this work is to explore the radiobiologic effect of prolonged fraction delivery time on tumor response and survival in vivo. METHODS: 1-cm-diameter Lewis lung cancer tumors growing in the legs of C57BL mice were used. To evaluate effect of dose delivery prolongation, 18 Gy was divided into different subfractions. 48 mice were randomized into 6 groups: the normal control group, the single fraction with 18 Gy group, the two subfractions with 30 min interval group, the seven subfractions with 5 min interval group, the two subfractions with 60 min interval group and the seven subfractions with 10 min interval group. The tumor growth tendency, the tumor growth delay and the mice survival time were analyzed. RESULTS: The tumor growth delay of groups with prolonged delivery time was shorter than the group with single fraction of 18 Gy (P < 0.05). The tumor grow delay of groups with prolonged delivery time 30 min was longer than that of groups with prolonged delivery time 60 min P < 0.05). There was no significant difference between groups with same delivery time (P > 0.05). Compared to the group with single fraction of 18 Gy, the groups with prolonged delivery time shorten the mice survival time while there was no significant difference between the groups with prolonged delivery time 30 min and the groups with prolonged delivery time 60 min. CONCLUSIONS: The prolonged delivery time with same radiation dose shorten the tumor growth delay and survival time in the mice implanted with Lewis lung cancer. The anti-tumor effect decreased with elongation of the total interfractional time.

mTHPC-mediated photodynamic treatment of Lewis lung carcinoma in vitro and in vivo.

BACKGROUND AND OBJECTIVE: The ongoing search for the enhancement of efficacy of photodynamic therapy stimulates the interest in molecular mechanisms of the response to the treatment. Looking for the cell line suitable for investigation of cellular response both in vivo and in vitro, we evaluated phototoxicity of m-tetrakis-(3-hydroxyphenyl)-chlorin (mTHPC) on viability of Lewis lung carcinoma (LLC1) cells in vitro, growth of murine transplantable tumor, and mice survival. MATERIAL AND METHODS: LLC1 cell culture and male C57BL/6 mice bearing Lewis lung carcinoma were used for the experiments. Photodynamic treatment was mediated by m-tetrakis-(3-hydroxyphenyl)-chlorin as a photosensitizer. Light emitting diode array was used for illumination. The effect of the photodynamic treatment was evaluated by comparison of viability of control and treated cells, growth of tumors, and survival of the control and treated mice. RESULTS: In vitro, a cytotoxic dose inducing a reduction in viability of LLC1 cells by 50% was achieved at 60 mJ/cm(2) and approximately 400 ng/mL of the photosensitizer, or 30 mJ/cm(2) and 600 ng/mL of mTHPC. Both the concentration of the photosensitizer and duration of light exposure were significant determinants of cytotoxic effect. In vivo, an injection of 0.25 mg/kg of mTHPC to mice bearing Lewis lung tumor and illumination at 120 J/cm(2) taking place after 24 h significantly inhibited tumor growth and prolonged mice survival. However, the tumors regained their growth potential after 9 days. CONCLUSIONS: Photodynamic treatment mediated by m-tetrakis-(3-hydroxyphenyl)-chlorin had a significant effect on LLC1 cells in vitro and growth of Lewis lung carcinoma in vivo.