CT26-bearing Mice Research Articles

Biomimetic modification of macrophage membrane-coated prussian blue nanoparticles loaded with SN-38 to treat colorectal cancer by photothermal-chemotherapy.

SN-38 is the active metabolite of irinotecan and acts as an effective topoisomerase I inhibitor with therapeutic effects on many malignant tumors, including some drug-resistant cancers. However, the poor solubility, low bioavailability, and severe dose-dependent toxicity limits the clinical application of SN-38. Currently, emerging macrophage membrane-coated nanoparticles provide an efficient biomimetic approach to develop novel SN-38 formulations for the reduction of its side effects. Photothermal therapy (PTT) is a promising methods in tumor treatment to thermally ablate tumors using various materials such Prussian blue nanoparticles (NPs) and can combined with chemotherapy to synergistically work. There is no report that combined SN38 and photothermal therapy for the treatment of colorectal cancer (CRC). SN38-PB@CM NPs were constructed by loading SN-38 into macrophage cell membrane-coated hollow mesoporous Prussian blue (PB) NPs. The morphology, size and zeta potential were evaluated by transmission microscopy and dynamic light scatter (DLS). Coomassie bright blue staining was performed to assess total protein profile. The photothermal properties of it were also investigated via near-infrared imaging. CCK8 and calcein-AM/PI staining were used to evaluate cell viability. Flow cytometry was performed to assess cell apoptosis. The fluorescent microscopy was used to observe cellular uptake of SN38-PB@CM NPs to assess its internalization in vitro. The biodistribution, tumor-targeting efficacy, antitumor efficacy and safety of SN38-PB@CM NPs in vivo were assessed in CT26 tumor-bearing mice via In Vivo Imaging System. SN38-PB@CM NPs were successfully constructed and exhibited a uniform size distribution (140.5 ± 4.3nm) and an excellent drug-loading capacity (5.61 ± 0.64%). SN38-PB@CM NPs showed stable release properties within 72h. It can also enhance the selective intracellular delivery of SN38 in vitro and showed good near-infrared (NIR) photothermal properties. And the NPs showed excellent tumor targeting, effective photothermal therapy, improved biosafety and antitumor efficacy on CT26-bearing mice. Multifunctional SN38-PB@CM NPs could achieve improved biosafety, great tumor-targeting, high-efficiency PTT and excellent antitumor efficacy, which provided a promising and attractive combination therapy for the treatment of CRC.

Resistant Starch-Encapsulated Probiotics Attenuate Colorectal Cancer Cachexia and 5-Fluorouracil-Induced Microbial Dysbiosis.

5-Fluorouracil (5-FU) is commonly used as the primary chemotherapy for colorectal cancer (CRC). However, it can lead to unwanted chemoresistance. Resistant starch (RS), which functions similarly to fermentable dietary fiber, has the potential to reduce the risk of CRC. The effects of RS on improving CRC-associated cachectic symptoms and 5-FU chemotherapy-induced microbial dysbiosis remain unknown. Female BALB/cByJNarl mice were randomly divided into four groups: one tumor group (with CT26 colonic carcinoma but no treatment) and three CT26 colonic carcinoma-bearing groups that were administered 20 mg/kg 5-FU (T+5-FU group), a probiotic cocktail (4 × 108 CFUs) plus chemotherapy (T+5-FU+Pro), or resistant-starch-encapsulated probiotics plus chemotherapy (T+5-FU+RS-Pro). T+5-FU and T+5-FU+RS-Pro administration significantly suppressed tumor growth and activated apoptotic cell death in CT26-bearing mice. 5-FU-induced increases in inflammatory cytokines and NF-κB signaling were mitigated by the Pro or RS-Pro supplementation. A gut microbial composition comparison indicated that the abundance of intestinal bacteria in the T and T+5-FU groups decreased significantly, while the groups receiving Pro or RS-Pro maintained a greater abundance and healthy gut microbiota composition, suggesting that RS can reduce the microbial dysbiosis that occurs during 5-FU chemotherapy. The use of RS-Pro before chemotherapy should be considered for the regulation of chemotherapy-associated cachectic symptoms, inflammation, and chemotherapy-induced microbial dysbiosis.

PD-L1 targeted peptide demonstrates potent antitumor and immunomodulatory activity in cancer immunotherapy.

In recent years, immunotherapy has been emerging as a promising alternative therapeutic method for cancer patients, offering potential benefits. The expression of PD-L1 by tumors can inhibit the T-cell response to the tumor and allow the tumor to evade immune surveillance. To address this issue, cancer immunotherapy has shown promise in disrupting the interaction between PD-L1 and its ligand PD-1. We used mirror-image phage display technology in our experiment to screen and determine PD-L1 specific affinity peptides (PPL-C). Using CT26 cells, we established a transplanted mouse tumor model to evaluate the inhibitory effects of PPL-C on tumor growth in vivo. We also demonstrated that PPL-C inhibited the differentiation of T regulatory cells (Tregs) and regulated the production of cytokines. In vitro, PPL-C has a strong affinity for PD-L1, with a binding rate of 0.75 μM. An activation assay using T cells and mixed lymphocytes demonstrated that PPL-C inhibits the interaction between PD-1 and PD-L1. PPL-C or an anti-PD-L1 antibody significantly reduced the rate of tumor mass development in mice compared to those given a control peptide (78% versus 77%, respectively). The results of this study demonstrate that PPL-C prevents or retards tumor growth. Further, immunotherapy with PPL-C enhances lymphocyte cytotoxicity and promotes proliferation in CT26-bearing mice. PPL-C exhibited antitumor and immunoregulatory properties in the colon cancer. Therefore, PPL-C peptides of low molecular weight could serve as effective cancer immunotherapy.

Curcuma xanthorrhiza extract and xanthorrhizol ameliorate cancer-induced adipose wasting in CT26-bearing mice by regulating lipid metabolism and adipose tissue browning

BackgroundCancer cachexia—characterized by anorexia, body weight loss, skeletal muscle atrophy, and fat loss—affects nearly 80% of cancer patients and accounts for 20% of cancer deaths. Curcuma xanthorrhiza, known as Java turmeric, and its active compound xanthorrhizol (XAN) exhibit anticancer, anti-inflammatory, and antioxidant properties. However, the ameliorative effects of C. xanthorrhiza extract (CXE) and XAN on cancer-associated adipose atrophy remain unexplored. This study aimed to evaluate the therapeutic effects of CXE and XAN on cancer cachexia-induced adipose tissue wasting in CT26 tumor-bearing mice. MethodsCT26 cells were injected subcutaneously into the right flank of BALB/c mice to establish a cancer cachexia model. To evaluate the inhibitory effects of CXE and XAN on cancer cachexia, 50 and 100 mg/kg CXE and 15 mg/kg XAN were administered orally every day for 1 week. ResultsCXE and XAN administration significantly attenuated the loss of body weight and epidydimal fat mass by cancer cachexia. In epididymal adipose tissues, administration of CXE or XAN inhibited white adipose tissue browning by repressing expression of the thermogenic genes. Simultaneously, CXE or XAN attenuated fat catabolism through the downregulation of lipolytic genes. The administration of CXE or XAN induced the expression of genes associated with adipogenesis and lipogenesis-related genes. Moreover, CXE or XAN treatment was associated with maintaining metabolic homeostasis; regulating the expression of adipokines and AMP-activated protein kinase (AMPK). ConclusionsCXE and XAN mitigate cancer-induced adipose tissue atrophy, primarily by modulating lipid metabolism and WAT browning, indicating their therapeutic potential for cachectic cancer patients.

Bacterial Expression of Promelittin for Safe and Effective Tumor Therapy.

Bacteria-based tumor therapy has attracted much attention due to its unique mechanism and abundant application. With the rapid development of synthetic biology, utilizing gene technology to make bacteria express therapeutic agents has greatly innovated bacterial therapy paradigms. Herein, we constructed an Escherichia coli expressing promelittin protein system based on the Trojan horse strategy, which limited the toxicity of melittin through the fusion protein during melittin expression. After targeted colonization of bacteria in tumor tissues, promelittin was activated by matrix metalloproteinase, followed by causing tumor cell death through a membrane-lytic mechanism. Additionally, the released cytolytic melittin in turn killed the maternal bacteria, eliminating safety hazards and triggering host immunity. Detailed experiments revealed that the bacteria expressing the promelittin system could significantly inhibit the proliferation and metastasis of primitive tumors in a CT26-bearing mice model. This study sheds insights into the development of bacteria-based synergistic tumor therapy.

Robust IL-2-dependent antitumor immunotherapy requires targeting the high-affinity IL-2R on tumor-specific CD8+ T cells

BackgroundDevelopment of interleukin (IL)-2-dependent antitumor responses focus on targeting the intermediate affinity IL-2R to stimulate memory-phenotypic CD8+ T and natural killer (NK) cells while minimizing regulatory T cell (Treg) expansion....

Microwave ablation induces abscopal effect via enhanced systemic antitumor immunity in colorectal cancer.

Thermal ablation is the primary procedure for the local treatment of lung metastases. It is known that radiotherapy and cryoablation can stimulate an abscopal effect, while the occurrence of abscopal effect induced by microwave ablation is less; the cellular and molecular mechanisms involved in the abscopal effect after microwave ablation should be further elucidated. CT26 tumor-bearing Balb/c mice were treated with microwave ablation with several combinations of ablation power and time duration. The growth of primary or abscopal tumors and the survival of mice were both monitored; moreover, immune profiles in abscopal tumors, spleens, and lymph nodes were examined by flow cytometry. Microwave ablation suppressed tumor growth in both primary and abscopal tumors. Both local and systemic T-cell responses were induced by microwave ablation. Furthermore, the mice exhibiting significant abscopal effect after microwave ablation markedly elevated Th1 cell proportion both in the abscopal tumors and spleens. Microwave ablation at 3 w-3 min not only suppressed tumor growth in the primary tumors but also stimulated an abscopal effect in the CT26-bearing mice via the improvement of systemic and intratumoral antitumor immunity.

GRIK5 stimulates colon cancer growth and metastasis through cAMP/PKA/CADM3 signaling.

Glutamate receptor, ionotropic, kainate 5 (GRIK5) is a member of glutamate receptors participating, and the kainate receptor family has been proved to regulate cell proliferation and transformation. Our study aimed at exploring the role of GRIK5 in colon tumor progression. Three hundred and ninety eightcolon cancer patients in The Cancer Genome Atlas Program (TCGA) data set and 26 clinical colon cancer patients were included for GRIK5 expression and prognosis analysis. GRIK5 overexpressed HCT116 and CT26 cell lines were established for cell proliferation and Transwell assay. Western blot analysis and immunostaining assay was conducted to evaluate the activation of activation of cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)/cell adhesion molecular 3 (CADM3) signaling in cell lines and tumor tissues. Subcutaneous CT26-bearing mice model was established to examine GRIK5-induced tumor growth and metastasis in vivo. Our study identified GRIK5 to be upregulated in patients with colon cancer, and higher GRIK5 levels correlated with the poor overall survival in patients. In vitro, GRIK5 overexpression markedly enhanced the proliferative properties and aggressive behaviors of colon cancer cells. Mechanistically, GRIK5 induced the activation of cAMP/PKA signaling, proceeded with augmented CADM3 expression, eventually resulting in sustained tumor growth.GRIK5 was a crucial scaffold in enabling colon cancer growth and metastasis, which offered a promising target for therapeutic manipulation of colon cancer.

Neutrophil membrane-derived nanoparticle loading TLR7 agonists augments radiotherapy efficacy and boosts abscopal effect via regulating tumor microenvironment

BackgroundIncreasing evidence indicates that radiotherapy (RT) has synergistic inhibitory efficiency with immunotherapy agents in multiple cancers and enhances abscopal effects by regulating the innate immune response, which was further investigated in this study. Neutrophils are recruited in radiated tumors. Therefore, neutrophil membrane-coated nanoparticles potentially deliver R837 (Toll-like receptor 7 agonist) to radiated tumors.MethodsA novel nanoparticle R837@PLGA@Neu was prepared by initially assembling PLGA (poly (lactic-co-glycolic acid)) with R837 (TLR7 agonist) into R837@PLGA followed by coating with neutrophil membrane. Characterizations of R837@PLGA@Neu were performed. Tumor targeting efficiency was evaluated by in vivo fluorescent imaging of CT26-bearing mice. Treatments of R837@PLGA@Neu combined with RT were carried out in unilateral and bilateral CRC tumor-bearing mice, followed by validations of immune cells in tumors by flow cytometry.ResultsThe characteristics of R837@PLGA@Neu were well identified, and it was confirmed to have high uptake ability and low cytotoxicity in colorectal cancer (CRC) cells in vitro, as well as its strong tumor-targeting efficiency in vivo in CRC tumor-bearing mice. The exciting findings were that R837@PLGA@Neu combined with RT exerted prominent tumor inhibition not only in radiated tumors, but also in distant tumors without RT, suggesting its enhancement of the efficacy and abscopal effect of RT. The possible underlying mechanisms were remodeling of the tumor microenvironment by triggering mature dendritic cells and CD8+ T cells.ConclusionIn summary, our findings suggested that neutrophil membrane-derived nanoparticle R837@PLGA@Neu with high uptake ability and low cytotoxicity showed strong tumor-targeting efficiency, and combination with RT had a promising effect in CT26-bearing mice via immune cell regulation. Our results provide a probable combination strategy for CRC treatment.

Novel Nanotherapeutics for Cancer Immunotherapy by PD-L1-Aptamer-Functionalized and Fexofenadine-Loaded Albumin Nanoparticles.

Immune checkpoint blockade (ICB) is an important strategy for cancer treatment and has achieved remarkable clinical results. Further enhancement of the efficacy of ICB therapy with a new technical approach is of potential medical importance. In this study, we constructed a novel nanotherapeutic agent (PDL1-NP-FEXO) for cancer immunotherapy by attaching PD-L1 aptamers to albumin nanoparticles that were loaded with H1-antihitamine fexofenadine (FEXO). FEXO has been reported to enhance the immunotherapy response by reducing the immunosuppressive M2-like macrophages in the tumor microenvironment. The albumin nanoparticle was fabricated using a self-assembly method. A dynamic light scattering (DLS) study revealed that the average size of PD-L1 aptamer-modified nanoparticle without FEXO (PDL1-NP) was 135.5 nm, while that of PDL1-NP-FEXO was 154.6 nm. Similar to free PD-L1 aptamer, PDL1-NP could also bind with PD-L1-expressing tumor cells (MDA-MB-231). Of note, compared with free PD-L1 aptamer, PDL1-NP significantly boosted tumor inhibition in CT26-bearing mice. Moreover, PDL1-NP-FEXO further enhanced the antitumor efficacy vs. PDL1-NP in an animal model, without raising systemic toxicity. These results indicate that PDL1-NP-FEXO represents a promising strategy to improve ICB efficacy and may have application potential in cancer immunotherapy.

A modulatory effect of L-arginine supplementation on anticancer effects of chemoimmunotherapy in colon cancer-bearing aged mice.

Myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) are increased in cancer-bearing aged hosts. Arginase-I in MDSCs degrades L-arginine, an amino acid required for T cell activation and proliferation. In this study, we compared the therapeutic efficacy of 5-fluorouracil (5-FU)/oxaliplatin (L-OHP) and cyclophosphamide (CP) between young and aged colon cancer-bearing mice. Therapy with 5-FU/L-OHP and CP significantly suppressed the in vivo growth of CT26 and MC38 colon carcinomas in syngeneic young mice, whereas this effect was attenuated in aged mice. L-arginine monotherapy showed no effect in aged mice. However, additional therapy with anti-programmed cell death (PD)-1 antibody and L-arginine supplementation boosted the effect of chemoimmunotherapy in aged mice, and some mice were cured. During all combination therapy, tumor-specific cytotoxic T lymphocytes (CTLs) were generated from mice with non-progressing tumor, but not from those with progressing tumor. Plasma L-arginine levels were lower in aged than young mice, and chemotherapy tended to decrease the plasma L-arginine levels in aged mice. Compared to young mice, CT26-bearing aged mice decreased arginase activity, arginase-I expression, and the proportion of monocytic MDSCs in tumor tissues, whereas contrasting results were observed in MC38-bearing aged mice. Importantly, the induction of tumor-specific CTLs was impaired at lower doses of L-arginine in vitro, and the infiltration of CTLs into CT26 tissues after chemoimmunotherapy was promoted by L-arginine administration in vivo. These results indicate that chemoimmunotherapy was less effective in cancer-bearing aged mice, but that L-arginine supplementation can modulate its therapeutic efficacy via its effect on tumor-specific CTLs.

Chidamide plus Tyrosine Kinase Inhibitor Remodel the Tumor Immune Microenvironment and Reduce Tumor Progression When Combined with Immune Checkpoint Inhibitor in Naïve and Anti-PD-1 Resistant CT26-Bearing Mice.

Combined inhibition of vascular endothelial growth factor receptor (VEGFR) and the programmed cell death protein 1 (PD-1) pathways has shown efficacy in multiple cancers; however, the clinical outcomes show limited benefits and the unmet clinical needs still remain and require improvement in efficacy. Using murine colon carcinoma (CT26) allograft models, we examined the efficacy and elucidated novel tumor microenvironment (TME) remodeling mechanisms underlying the combination of chidamide (a benzamide-based class l histone deacetylase inhibitor; brand name in Taiwan, Kepida®) with VEGF receptor tyrosine kinase inhibitor (TKIs; cabozantinib/regorafenib, etc.) and immune checkpoint inhibitors (ICIs; anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies). The TME was assessed using flow cytometry and RNA-sequencing to determine the novel mechanisms and their correlation with therapeutic effects in mice with significant treatment response. Compared with ICI alone or cabozantinib/regorafenib + ICI, combination of chidamide + cabozantinib/regorafenib + ICI increased the tumor response and survival benefits. In particular, treatment of CT26-bearing mice with chidamide + regorafenib + anti-PD-1 antibody showed a better objective response rate (ORR) and overall survival (OS). Similar results were observed in anti-PD-1 treatment-resistant mice. After treatment with this optimal combination, in the TME, RNA-sequencing revealed that downregulated mRNAs were correlated with leukocyte migration, cell chemotaxis, and macrophage gene sets, and flow cytometry analysis showed that the cell numbers of myeloid-derived polymorphonuclear suppressor cells and tumor-associated macrophages were decreased. Accordingly, chidamide + regorafenib + anti-PD-1 antibody combination therapy could trigger a novel TME remodeling mechanism by attenuating immunosuppressive cells, and restoring T-cell activation to enhance ORR and OS. Our studies also showed that the addition of Chidamide to the regorafenib + anti-PD-1 Ab combination could induce a durable tumor-specific response by attenuating immune suppression in the TME. In addition, this result suggests that TME remodeling, mediated by epigenetic immunomodulator combined with TKI and ICI, would be more advantageous for achieving a high objective response rate, when compared to TKI plus ICI or ICI alone, and maintaining long-lasting antitumor activity.

Corrigendum: Swimming attenuates muscle wasting and mediates multiple signaling pathways and metabolites in CT-26 bearing mice

[This corrects the article DOI: 10.3389/fmolb.2021.812681.].

Japanese Kampo Medicine Juzentaihoto Improves Antiviral Cellular Immunity in Tumour-Bearing Hosts.

Global and antigen-independent immunosuppression by growing tumours can cause life-threating damage when concurrent with an infection in tumour-bearing hosts. In the present study, we investigated whether the oral administration of the Japanese traditional herbal (Kampo) medicine, juzentaihoto (JTT), plays a role in the improvement of antiviral cellular immunity in tumour-bearing hosts. Female BALB/c mice subcutaneously injected with murine colorectal cancer CT26 cells fed a control or JTT diet were inoculated with recombinant vaccinia virus expressing human immunodeficiency virus-1 glycoprotein 160 (vSC25). At 7 days postinfection, anti-vSC25 cellular immunity was evaluated by measuring the abundance of splenic virus-specific CD8+ T cells. JTT had no impact on CT26 tumour growth in vivo. Surprisingly, JTT augmented anti-vSC25 cellular immunity in CT26-bearing mice. Depletion of either CD25+ regulatory T (Treg) cells or myeloid-derived suppressor cells (MDSCs) also enhanced anti-vSC25 cellular immunity in tumour-bearing mice but had no therapeutic benefit against tumour growth. However, JTT had no impact on the abundance of these immunosuppressive cells. Overall, our data indicates that JTT contributes to the improvement of anti-vSC25 cellular immunity in tumour-bearing hosts possibly via a mechanism independent of CD25+ Treg cells and MDSCs, suggesting that this Kampo medicine can act as a promising antiviral adjuvant in an immunosuppressive state caused by tumours.

Abstract 6025: Baseline cytokine profiling in naïve and tumor-bearing Balb/c and C57BL/6 Charles River mice

Abstract Background: Syngeneic studies are still the backbone of oncology research. These rely on immunocompetent mice to model anti-cancer immune responses elicited by experimental treatments. Cytokines mediate these responses through cell signaling, which contributes to an immunosuppressive milieu in the tumor microenvironment. Determining the secretion patterns of these protein modulators can help understand pathogenesis, disease progression and resistance to targeted therapies. To evaluate biological effects of potential interventions, we compared systemic cytokine activities in naïve and untreated tumor-bearing Balb/c and C57BL/6 mice. Study Details: Charles River wild type Balb/c (n=9) and C57BL/6 (n=10) mice were used for all experiments. CT26 and B16.F10 tumor cell lines for inoculations were purchased from ATCC (Manassas, VA). Serum samples were collected from colon carcinoma (Balb/c) and melanoma (C57BL/6) bearing mice as well as tumor-free animals. For rapid multiplex measurements on the Meso Scale Discovery platform the V-PLEX Proinflammatory Panel 1 Mouse Kit was used (cat no. K15048D-1). IFN-γ, IL-1β, IL-2, IL-4, IL-5, IL-6, KC/GRO, IL-10, IL-12p70, and TNF-α were detected simultaneously by electrochemiluminescence within the manufacturer’s specification for each analyte. Results: Sera from CT26 and B16.F10 tumor-bearing mice exhibited higher average concentrations of IFN-γ, IL1-β, IL-4, IL-10, KC/GRO and TNF-α, when compared to naïve mice of the Balb/c or C57BL/6 background, respectively; however, IL-2 production was found increased in tumor-bearing Balb/c and decreased in tumor-bearing C57BL/6 mice. Though known to be promoting tumor growth, IL-6 was only measurable in three out of ten B16.F10-bearing mice and below the limit of detection in CT26-bearing mice. IL-5 and IL-12 p70 levels showed no difference between CT26-bearing and naïve Balb/c mice, whereas both cytokines were elevated in the B16.F10 model over naïve C57BL/6 mice. Conclusions: Circulating serum cytokines have been quantified in commonly used syngeneic mouse strains with and without tumor burden. These reference data provide baseline levels to compare soluble proinflammatory biomarkers suitable for assessing potential immunomodulatory effects of experimental cancer treatments in combination with other pharmacodynamic readouts. Citation Format: Kenneth Munroe, Christoph S. Eberle, Robert Mihalek, Stephen Festin. Baseline cytokine profiling in naïve and tumor-bearing Balb/c and C57BL/6 Charles River mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6025.

Targeting the high-affinity IL-2R with high-dose mIL-2/CD25 induces effective antitumor responses

Abstract Much interest remains to harness the T cell activating properties of IL-2 to promote antitumor immunity. Current efforts largely utilize approaches directed toward the intermediate-affinity IL-2R to broadly stimulate memory-phenotypic CD8+ T and NK cells while minimizing off-target Tregs. However, this approach does not effectively engage tumor-reactive CD4+ and CD8+ T effector cells that express the high-affinity IL-2R. Recently, we developed a fusion protein where mouse IL-2 was linked to CD25 (mIL-2/CD25 or FP) with selectivity toward the high-affinity IL-2R. At a low dose, the FP is Treg-selective to limit autoimmunity, but at a high dose with a tumor vaccine it expands tumor-reactive T cells to develop antitumor immunity. Here, we assessed the efficacy of high-dose (HD) FP as a cancer monotherapy or with checkpoint blockade. HD FP supports antitumor responses in mice bearing CT26, MC38, or B16.F10 tumors. Although HD FP led to increases in Tregs in immune tissues, Tregs were at a lower frequency in the tumor microenvironment (TME), leading to a high CD8+ T cell:Treg ratio. Further, adding anti-PD-1 to HD FP treatment was more effective in controlling tumors in CT26-bearing mice. Surprisingly, at the doses tested, HD FP supported more robust antitumor responses in each model than IL-2/S4B6 anti-IL-2 complexes (IL2/IC), directed to the intermediate-affinity IL-2R. In the CT26 TME, the number of tumor antigen-specific CD8+ T cells trended upward with HD FP over IL2/IC. These studies indicate that targeting the high-affinity IL-2R on activated tumor-specific T cells with HD FP alone or with PD-1 blockade supports antitumor responses and suggests that this strategy may be more effective than targeting the intermediate-affinity IL-2R. Supported by Bristol Myers Squibb grant support

Newcastle disease virus expressing an angiogenic inhibitor exerts an enhanced therapeutic efficacy in colon cancer model.

Newcastle disease virus (NDV)-mediated gene therapy is a promising new approach for treatment of cancer but shows limited anti-angiogenesis. VEGF-Trap plays a vital role in anti-angiogenesis. To enhance the anti-tumor effect of NDV, VEGF-Trap gene was incorporated into the genome of rNDV in this study (named rNDV-VEGF-Trap). Results showed that rNDV-VEGF-Trap reduced cell growth ratio by 85.37% and migration ratio by 87.9% in EA.hy926 cells. In vivo studies, rNDV-VEGF-Trap reduced tumor volume and weight of CT26-bearing mice by more than 3 folds. Immunohistochemistry analysis of CD34 showed rNDV-VEGF-Trap significantly decreased the number of vascular endothelial cells in the tumor tissues. Moreover, Western blot analysis demonstrated that treatment with rNDV-VEGF-Trap significantly decreased the phosphorylation levels of AKT, ERK1/2 and STAT3 and increased the expression levels of P53, BAX and cleaved caspase-3 in the tumor tissue. In addition, to evaluate the toxicity of rNDV-VEGF-Trap, serum chemistries were analyzed. The results showed that rNDV-VEGF-Trap caused insignificant changes of creatinine levels, alanine aminotransferase and aspartate transaminase. Furthermore, administration of rNDV-VEGF-Trap did not cause the diarrhoea, decreased appetite, weight decrease and haemorrhage of the experimental mice. These data suggest that rNDV-VEGF-Trap exhibits an enhanced inhibition of CT26-bearing mice by enhancing anti-angiogenesis and apoptosis and may be a potential candidate for carcinoma therapy especially for colon cancer.

Swimming Attenuates Muscle Wasting and Mediates Multiple Signaling Pathways and Metabolites in CT-26 Bearing Mice.

Objectives: To investigate the effects of swimming on cancer induced muscle wasting and explore its underlying mechanism in CT-26 bearing mice. Methods: BALB/c mice (n = 16) injected with CT-26 cells were divided into two groups, including Tumor group (n = 8) and Swimming group (n = 8). Another 8 un-injected mice were set as Control group. Mice in Swimming group were subjected to physical training for swimming twice per day for 30 min intervals and 6 days per week for a total of 4 weeks. The tumor volume was monitored every 3 days and tumor weight was measured at the end of experiment. The changes of muscle function, pathological and cell apoptosis of quadriceps muscles were further assessed, and its underlying mechanisms were further explored using multiple biological technologies. Results: Swimming obviously alleviated tumor volume and weight in CT-26 bearing mice. Moreover, swimming attenuated the decrease of muscle tension, autonomic activities, and increase of muscle atrophy, pathological ultrastructure, as well as cell apoptosis of quadriceps muscles in CT-26 bearing mice. Furthermore, swimming significantly down-regulated the protein expression of NF-κB, p-NF-κB, TNF-α, IL-1β, IL-6 and Bax, while up-regulated the expression of Bcl-2. Further differential expressed metabolites (DEMs) analysis identified a total of 76 (in anion mode) and 330 (in cationic mode) DEMs in quadriceps muscles of CT-26 bearing mice after swimming, including taurochenodeoxycholic acid, taurocholic acid, ascorbic acid and eicosapentaenoic acid. Conclusion: Swimming attenuates tumor growth and muscle wasting, and by suppressing the activation of NF-κB signaling pathway mediated inflammation, reducing the level of Bax medicated cell apoptosis, as well as modulating multiple metabolites might be the importantly underlying mechanisms.

The Class I HDAC Inhibitor, MS-275, Prevents Oxaliplatin-Induced Chronic Neuropathy and Potentiates Its Antiproliferative Activity in Mice.

Oxaliplatin, the first-line chemotherapeutic agent against colorectal cancer (CRC), induces peripheral neuropathies, which can lead to dose limitation and treatment discontinuation. Downregulation of potassium channels, which involves histone deacetylase (HDAC) activity, has been identified as an important tuner of acute oxaliplatin-induced hypersensitivity. MS-275, a class I histone deacetylase inhibitor (HDACi), prevents acute oxaliplatin-induced peripheral neuropathy (OIPN). Moreover, MS-275 exerts anti-tumor activity in several types of cancers, including CRC. We thus hypothesized that MS-275 could exert both a preventive effect against OIPN and potentially a synergistic effect combined with oxaliplatin against CRC development. We first used RNAseq to assess transcriptional changes occurring in DRG neurons from mice treated by repeated injection of oxaliplatin. Moreover, we assessed the effects of MS-275 on chronic oxaliplatin-induced peripheral neuropathy development in vivo on APCMin/+ mice and on cancer progression when combined with oxaliplatin, both in vivo on APCMin/+ mice and in a mouse model of an orthotopic allograft of the CT26 cell line as well as in vitro in T84 and HT29 human CRC cell lines. We found 741 differentially expressed genes (DEGs) between oxaliplatin- and vehicle-treated animals. While acute OIPN is known as a channelopathy involving HDAC activity, chronic OIPN exerts weak ion channel transcriptional changes and no HDAC expression changes in peripheral neurons from OIPN mice. However, MS-275 prevents the development of sensory neuropathic symptoms induced by repeated oxaliplatin administration in APCMin/+ mice. Moreover, combined with oxaliplatin, MS-275 also exerts synergistic antiproliferative and increased survival effects in CT26-bearing mice. Consistently, combined drug associations exert synergic apoptotic and cell death effects in both T84 and HT29 human CRC cell lines. Our results strongly suggest combining oxaliplatin and MS-275 administration in CRC patients in order to potentiate the antiproliferative action of chemotherapy, while preventing its neurotoxic effect.

Abstract 523: Modulation of immune suppressive cells by toll-like 7 agonist DSP-0509 which leads to potentiate anti-tumor activity of radiotherapy

Abstract Toll-like receptors (TLRs) are a family of pattern-recognition receptors that recognize pathogen-associated molecular patterns. TLR7 stimulation in pDCs (plasmacytoid dendritic cell) induces type I interferon, which results in innate immune activation. We previously showed that intravenously injectable DSP-0509 activated anti-tumor immunity in combination with immune checkpoint inhibitors. In this study, we present that DSP-0509 can enhance anti-tumor activity of radiation therapy (RT). RT is generally known to induce not only anti-tumor effector T cells through immunogenic cell death, but also cause immune suppression. We assessed the modulatory activity of DSP-0509 on immune suppressive cells. In CD8+ T cell suppression assay in which CD8+ T cells were cocultured with mMDSC (monocytic myeloid-derived suppressor cell, CD11b+Gr-1low), DSP-0509 restored the proliferation of CD8+ T cell suppressed by mMDSC. In Treg differentiation assay, in which Treg (CD4+CD25+Foxp3+) was differentiated from naïve CD4+ T cell in the presence of TGF-β, DSP-0509 suppressed the Treg differentiation. Treg function was assessed in coculture system, in which proliferation of CTV-labeled (CellTrace™ Violet) CD4+ T cell was suppressed by Treg. DSP-0509 restored the proliferation of CD4+ T cell. As a next step, to confirm a combination effect with RT, DSR-0509 (5 mg/kg, weekly) was administered with RT (5 Gy x 5 consecutive day). The combination administration extended the survival of CT26-bearing mice. The ratio of effector memory T cell (CD8+CD62L-CD127+) in CD8+ T cell was increased after administration of combination of DSP-0509 with RT. ELISpot assay using splenocytes collected from CT26-bearing mice after the administration of combination of DSP-0509 with RT was conducted. As a result, the number of IFNγ secreting cytotoxic T lymphocytes (CTLs) that responded to gp70 peptide was increased in combination of DSP-0509 with RT. When CT26 cells were re-challenged to the mice that completely rejected tumor after combination of DSP-0509 with RT, no tumor growth was observed in all mice. Anti-CD8 antibody treatment prior to re-challenge of CT26 cells cancelled this memory effect. qPCR analysis using mRNA isolated from treated tumor was conducted. RT monotherapy increased the expression of Cd8b1, but addition of DSP-0509 further enhanced the expression of Gzmb and Il12b in tumor. We showed two novel effects of DSP-0509 in this study, 1) modulation of immune suppressive cells and 2) extension of the survival of tumor-bearing mice in combination with RT, which would be explained by the additive CTL activation and memory T cell induction. Taken together, these results supported the hypothesis that combination of DSP-0509 with RT may enhance the anti-tumor immune activity by modulating CTL activity as well as immune suppressive cells. Citation Format: Yosuke Ota, Yasuhiro Nagai, Masashi Goto, Jun Oishi, Setsuko Yamamoto. Modulation of immune suppressive cells by toll-like 7 agonist DSP-0509 which leads to potentiate anti-tumor activity of radiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 523.