CT26 Murine Colon Carcinoma Cells Research Articles

Chemo-immunotherapy by dual-enzyme responsive peptide self-assembling abolish melanoma

Herein, we designed Comp. 1 to simultaneously respond to two enzymes: alkaline phosphatase and matrix metalloproteinase 2, which is commonly found in highly malignant cancer cell lines containing B16–F10 murine melanoma cells and CT26 murine colon carcinoma cells. We used the regional differences in the expression levels of dual-markers to accurately release immune molecule IND into tumor microenvironment for the activation of anti-tumor related immune effects, while in-situ self-assembly occurs. The dual-enzyme response process can further regulate the peptide precursors’ self-assembly in the form of short rod-shaped nanofibers, enabling the delivery of the loaded chemotherapeutic drug HCPT into the cancer cells and further allowing the peptide assemblies to escape from lysosomes and return to cytoplasm in the form of tiny nanoparticles to induce apoptosis of cancer cells. This process does not occur in the single-positive breast cancer cell line MCF-7 or the normal hepatocytes cell line LO2, indicating the selectivity of the cancer cells exhibited using our strategy. In vivo studies revealed that Comp. 1 can effectively cooperate with chemotherapy to enhance the immunotherapy effect and induce immune responses associated with elevated pro-inflammatory cytokines in vivo to inhibit malignant tumors growth. Our dual-enzyme responsive chemo-immunotherapy strategy feasible in anti-tumor treatment, provides a new avenue for regulating peptide self-assembly to adapt to diverse tumor properties and may eventually be used for the development of novel multifunctional anti-tumor nanomedicines.

Gene Immunotherapy of Colon Carcinoma with IL-2 and IL-12 Using Gene Electrotransfer.

Gene immunotherapy has become an important approach in the treatment of cancer. One example is the introduction of genes encoding immunostimulatory cytokines, such as interleukin 2 and interleukin 12, which stimulate immune cells in tumours. The aim of our study was to determine the effects of gene electrotransfer of plasmids encoding interleukin 2 and interleukin 12 individually and in combination in the CT26 murine colon carcinoma cell line in mice. In the in vitro experiment, the pulse protocol that resulted in the highest expression of IL-2 and IL-12 mRNA and proteins was used for the in vivo part. In vivo, tumour growth delay and also complete response were observed in the group treated with the plasmid combination. Compared to the control group, the highest levels of various immunostimulatory cytokines and increased immune infiltration were observed in the combination group. Long-term anti-tumour immunity was observed in the combination group after tumour re-challenge. In conclusion, our combination therapy efficiently eradicated CT26 colon carcinoma in mice and also generated strong anti-tumour immune memory.

Lactate oxidase/catalase-displaying nanoparticles efficiently consume lactate in the tumor microenvironment to effectively suppress tumor growth

The aggressive proliferation of tumor cells often requires increased glucose uptake and excessive anaerobic glycolysis, leading to the massive production and secretion of lactate to form a unique tumor microenvironment (TME). Therefore, regulating appropriate lactate levels in the TME would be a promising approach to control tumor cell proliferation and immune suppression. To effectively consume lactate in the TME, lactate oxidase (LOX) and catalase (CAT) were displayed onto Aquifex aeolicus lumazine synthase protein nanoparticles (AaLS) to form either AaLS/LOX or AaLS/LOX/CAT. These complexes successfully consumed lactate produced by CT26 murine colon carcinoma cells under both normoxic and hypoxic conditions. Specifically, AaLS/LOX generated a large amount of H2O2 with complete lactate consumption to induce drastic necrotic cell death regardless of culture condition. However, AaLS/LOX/CAT generated residual H2O2, leading to necrotic cell death only under hypoxic condition similar to the TME. While the local administration of AaLS/LOX to the tumor site resulted in mice death, that of AaLS/LOX/CAT significantly suppressed tumor growth without any severe side effects. AaLS/LOX/CAT effectively consumed lactate to produce adequate amounts of H2O2 which sufficiently suppress tumor growth and adequately modulate the TME, transforming environments that are favorable to tumor suppressive neutrophils but adverse to tumor-supportive tumor-associated macrophages. Collectively, these findings showed that the modular functionalization of protein nanoparticles with multiple metabolic enzymes may offer the opportunity to develop new enzyme complex-based therapeutic tools that can modulate the TME by controlling cancer metabolism.Graphical

Lactobacillus rhamnosus R0011 Treatment Enhanced Efficacy of Capecitabine against Colon Cancer in Male Balb/c Mice

The microbiome of the intestinal system is well-known as a modulatory factor. Having a balanced status of microbiota could help to prevent diseases, especially cancers related to the gastrointestinal system. We investigated the effects of Lactobacillus rhamnosus (Lr) and capecitabine on tumor size and physiologic features, such as bodyweight, liver enzymes, and blood profile, in a subcutaneously induced cancer model using CT-26 murine colon carcinoma cells. We divided 48 male Balb/c inbred mice into six groups. Lr had been orally pre-inoculated to the mice for 14 day consecutively. CT-26 cells were implanted subcutaneously into the mice’s flank. Following the injection of cancer cells, Lr was inoculated to the mice three times per week for four weeks. Capecitabine was inoculated in the third week after the induction of cancer. The tumor size was significantly decreased in treated groups in comparison to the cancer group (1174.5 ± 63.8, 1119.2 ± 86.3, and 985.6 ± 48 mm3 vs. 1674.2 ± 66 mm3, P < 0.0001). Data showed that Lr and capecitabine enhanced Bax/Bcl-2 ratio and caspase-3 level compared to cancer group (p < 0.0001). White blood cells (WBCs) were significantly decreased in the capecitabine group compared to probiotic group (P < 0.05). Measurement of bodyweight, liver enzymes, and interleukin-6 (IL-6) level showed that Lr, in addition to preventive and therapeutic effects, might have protective effects against chemotherapy side effects. Preventing WBCs’ reduction, protecting mice from losing weight, induction of apoptosis, and enhancing the serum level of IL-6 indicated that Lr might be associated with better management of colorectal cancer and chemotherapy side effects.

A novel method for the development of plasmid DNA-loaded nanoliposomes for cancer gene therapy.

We aimed to develop a simple yet novel method to prepare plasmid DNA-loaded nanoliposomes for cancer gene therapy. Murine interleukin-12 (mIL-12) pDNA-loaded nanoliposomes were prepared via novel freeze-drying of a monophase solution method. The physicochemical characteristics, cytotoxicity, and transfection efficiency of the prepared nanoliposomes in murine CT-26 colon carcinoma cells were evaluated. Furthermore, tumor progression and survival rate in CT-26 colon carcinoma-bearing BALB/c mice subsequent to direct intratumoral injections were investigated over a period of 40 days. Using this preparation method, nanoliposomes with particle size of around 300 nm and zeta potential of 96.5 mV were obtained. The transmission electron microscope results showed that the liposomes were nano-sized and almost spherical. The agarose gel retardation assay revealed the pDNA encapsulation in the nanoliposomes. The nanoliposomes with 72.4% encapsulation efficiency and low cell toxicity could significantly improve mIL-12 expression by approximately 25-fold relative to the naked mIL-12 pDNA. There was a significant tumor growth inhibition after repeated injections of mIL-12 pDNA-loaded nanoliposomes. This is the first study on the freeze-drying of a monophase solution method as a simple yet novel technique for the preparation of pDNA-loaded nanoliposomes. Given the ease of preparation method and promising in vitro and in vivo characteristics, this investigation demonstrates advances in pDNA lipid formulation for cancer gene therapy.

Enhancement of cytotoxicty of diallyl disulfide toward colon cancer by Eudragit S100/PLGA nanoparticles

According to WHO cancer is the second leading cause of death globally, amounting to about 1 in 6 deaths. Among these, colon cancer is the third leading cause of mortalities worldwide. Current measures for cancer treatment: chemotherapy, radiation, and surgery are accompanied by myriad side effects. In light of a mediocre success of synthetic drugs against cancer exploring the treasure of naturally occurring compounds with anti-cancer activity can be an effective strategy. Diallyl disulfide (DADS), a dietary phytochemical derived from garlic possesses a substantial anti-cancer activity against colon cancer. Nevertheless, its poor water solubility and restricted selectivity towards tumor tissues have limited its clinical applications. Moreover, to deliver intact drugs is another major concern in the treatment of ailments associated with the colon. To address these aforementioned clinically significant issues, we report dual functioning DADS loaded polymeric nanoparticles composed of a combination of Eudragit S100 (ES100) as a pH-sensitive polymer for targeted delivery to colon and poly (lactic-co-glycolic acid) (PLGA) as a biodegradable polymer for sustained release of DADS along with their physicochemical characteristics. Secondly, we report in-vitro cytotoxicity study, cell cycle analysis, and cellular uptake study of DADS loaded polymeric nanoparticles (ES100/PLGA-NPs) in CT26 murine colon carcinoma cells. ES100/PLGA-NPs elucidated higher cell growth inhibition and low IC50 value, in comparison to free DADS. Cellular uptake study exhibited the internalization of ES100/PLGA-NPs. These outstanding data illuminate that the fabricated polymeric nanoparticles as an effective modality for site-specific targeting and its use to augment the efficacy of highly hydrophobic dietary phytochemicals locally in the inflamed colon while minimizing systemic side effects.

Magnetic molding of tumor spheroids: emerging model for cancer screening

Three-dimensional tissue culture, and particularly spheroid models, have recently been recognized as highly relevant in drug screening, toxicity assessment and tissue engineering due to their superior complexity and heterogeneity akin to the in vivo microenvironment. However, limitations in size control, shape reproducibility and long maturation times hinder their full applicability. Here, we report a spheroid formation technique based on the magnetic aggregation of cells with internalized magnetic nanoparticles. The method yields magnetic spheroids with high sphericity and allows fine-tuning the final spheroid diameter. Moreover, cohesive spheroids can be obtained in less than 24 h. We show the proof of concept of the method using the CT26 murine colon carcinoma cell line and how different cell proliferation and invasion potentials can be attained by varying the spheroid size. Additionally, we show how the spheroid maturation impacts cell invasion and doxorubicin penetrability, highlighting the importance of this parameter in drug screening and therapeutic applications. Finally, we demonstrate the capability of the method to allow the measurement of the surface tension of spheroids, a relevant output parameter in the context of cancer cell invasion and metastasis. The method can accommodate other cell lines able to be magnetically labeled, as we demonstrate using the U-87 MG human glioblastoma cell line, and shows promise in the therapeutic screening at early time points of tissue formation, as well as in studies of drug and nanoparticle tumor penetration.

Abstract 4532A: Development of selective small molecule STING agonists suitable for systemic administration

Abstract Background: Stimulator of Interferon Genes (STING) is a major player in the activation of robust innate immune response leading to initiation and enhancement of tumor-specific adaptive immunity. Several clinical and pre-clinical programs are developing cyclic dinucleotides - analogues of endogenous STING ligands. However their chemical nature and stability limit their use as systemic immuno-therapeutics. Herein, we present potent and selective non-nucleotide, non-macrocyclic, small molecule direct STING agonists, structurally unrelated to known chemotypes and suitable for systemic administration. Methods: Binding to recombinant STING protein was examined using FTS, MST, FP and crystallography studies. Phenotypic screen was performed in THP-1 Dual reporter cells. Human macrophages (HMDM) and dendritic cells (HMDC) were differentiated from monocytes (obtained from PBMC) in the presence of M-CSF and GM-CSF/IL-4 for HMDM and HMDC, respectively. Mouse bone marrow-derived dendritic cells (BMDC) were obtained from C57BL/6 or STING KO mice and differentiated with mIL-4 and mGM-CSF. STING agonists were administered into BALB/c mice and cytokine release was measured in plasma. Additionally, mice were inoculated with CT26 murine colon carcinoma cells and the compound was administered, followed by the regular tumor growth monitoring. Finally, the compound was administered to C57BL/6 WT and STING KO mice in several escalating doses. Results: Ryvu's agonists demonstrate a strong binding affinity to recombinant STING proteins across tested species. They trigger pro-inflammatory cytokine release from human PBMC and HMDC and induce dendritic cell maturation regardless of the STING haplotype. Systemic in vivo administration leads to dose-dependent upregulation of STING-dependent pro-inflammatory cytokines, suggesting immune activation which translates into efficacy in vivo in CT26 mouse colorectal cancer model and complete tumor remissions. Furthermore, cured animals develop lasting immunological response demonstrated by diminished tumor growth or lack of palpable tumors in re-challenged mice. Conclusion: Ryvu's STING agonists selectively activate STING-dependent signaling in both mouse and human immune cells promoting anti-tumor immunity. Treatment with Ryvu's STING agonists leads to engagement of the immune system which results in complete tumor remission and development of immunological memory against cancer cells. The compounds show good selectivity and ADME properties enabling development for systemic administration as a single agent or in combinations with immunotherapies or targeted agents. Citation Format: Stefan Chmielewski, Magdalena Zawadzka, Jolanta Mazurek, Maciej K. Rogacki, Karolina Gluza, Katarzyna Wójcik-Jaszczyńska, Aleksandra Poczkaj, Grzegorz Ćwiertnia, Grzegorz Topolnicki, Maciej Kujawa, Eliza Zimoląg, Urszula Głowniak-Kwitek, Magdalena Mroczkowska, Agnieszka Gibas, Marcin Leś, Sylwia Sudoł, Marek Wronowski, Kinga Michalik, Katarzyna Banaszak, Katarzyna Wiklik, Federico Malusa, Michał Combik, Karolina Wiatrowska, Łukasz Dudek, Jose Alvarez, Anna Rajda, Faustyna Gajdosz, Aniela Gołas, Katarzyna Wnuk-Lipińska, Kamil Kuś, Ewelina Gabor-Worwa, Charles Fabritius, Luigi Stasi, Peter Littlewood, Krzysztof Brzózka, Monika Dobrzańska. Development of selective small molecule STING agonists suitable for systemic administration [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4532A.

Enhanced Cellular Uptake and Photodynamic Effect with Amphiphilic Fluorinated Porphyrins: The Role of Sulfoester Groups and the Nature of Reactive Oxygen Species

A class of amphiphilic photosensitizers for photodynamic therapy (PDT) was developed. Sulfonate esters of modified porphyrins bearing—F substituents in the ortho positions of the phenyl rings have adequate properties for PDT, including absorption in the red, increased cellular uptake, favorable intracellular localization, low cytotoxicity, and high phototoxicity against A549 (human lung adenocarcinoma) and CT26 (murine colon carcinoma) cells. Moreover, the role of type I and type II photochemical processes was assessed by fluorescent probes specific for various reactive oxygen species (ROS). The photodynamic effect is improved not only by enhanced cellular uptake but also by the high generation of both singlet oxygen and oxygen-centered radicals. All of the presented results support the idea that the rational design of photosensitizers for PDT can be further improved by better understanding the determinants affecting its therapeutic efficiency and explain how smart structural modifications can make them suitable photosensitizers for application in PDT.

Surface Modification of Liposomes Using IR700 Enables Efficient Controlled Contents Release Triggered by Near-IR Light.

Stimuli-responsive liposomes are promising drug carriers for cancer treatment because they enable controlled drug release and the maintenance of desired drug concentrations in tumor tissue. In particular, near-IR (NIR) light is a useful stimulus for triggering drug release from liposomes based on its advantages such as deep tissue penetration and safety. Previously, we found that a silicon phthalocyanine derivative, IR700, conjugated to antibodies, can induce the rupture of the cell membrane following irradiation by NIR light. Based on this finding, we constructed IR700-modified liposomes (IR700 liposomes) and evaluated their drug release properties triggered by NIR light. IR700 liposomes released substantial amounts of encapsulated calcein following irradiation by NIR light. Drug release was substantially suppressed by the addition of sodium azide, suggesting that liposomal membrane permeabilization was mediated by singlet oxygen generated from IR700. Moreover, calcein release from IR700 liposomes triggered by NIR light was promoted under conditions of deoxygenation and the presence of electron donors. Thus, membrane disruption should be induced by the physical change of IR700 from highly hydrophilic to hydrophobic as we previously described, although singlet oxygen can cause a certain level of membrane disruption under normoxia. We also observed that doxorubicin-encapsulated IR700 liposomes exhibited significant cytotoxic effects against CT-26 murine colon carcinoma cells following NIR light exposure. These results indicate that IR700 liposomes can efficiently release anti-cancer drugs following NIR light irradiation even under hypoxic conditions and, therefore, they would be useful for cancer treatment.

Ultrasound-Sensitive Liposomes for Triggered Macromolecular Drug Delivery: Formulation and In Vitro Characterization.

Mistletoe lectin-1 (ML1) is a nature-derived macromolecular cytotoxin that potently induces apoptosis in target cells. Non-specific cytotoxicity to normal cells is one of the major risks in its clinical application, and we therefore propose to encapsulate ML1 in a nanocarrier that can specifically release its cargo intratumorally, thus improving the efficacy to toxicity ratio of the cytotoxin. We investigated the encapsulation of ML1 in ultrasound-sensitive liposomes (USL) and studied its release by high-intensity focused ultrasound (HAccessedIFU). USL were prepared by entrapment of perfluorocarbon nanodroplets in pegylated liposomes. The liposomes were prepared with different DPPC/cholesterol/DSPE-PEG2000 lipid molar ratios (60/20/20 for USL20; 60/30/10 for USL10; 65/30/5 for USL5) before combination with perfluorocarbon (PFC) nanoemulsions (composed of DPPC and perfluoropentane). When triggered with HIFU (peak negative pressure, 2–24 MPa; frequency, 1.3 MHz), PFC nanodroplets can undergo phase transition from liquid to gas thus rupturing the lipid bilayer of usl. Small unilamellar liposomes were obtained with appropriate polydispersity and stability. ML1 and the model protein horseradish peroxidase (HRP) were co-encapsulated with the PFC nanodroplets in USL, with 3% and 7% encapsulation efficiency for USL20 and USL10/USL5, respectively. Acoustic characterization experiments indicated that release is induced by cavitation. HIFU-triggered release of HRP from USL was investigated for optimization of liposomal composition and resulted in 80% triggered release for USL with USL10 (60/30/10) lipid composition. ML1 release from the final USL10 composition was also 80%. Given its high stability, suitable release, and ultrasound sensitivity, USL10 encapsulating ML1 was further used to study released ML1 bioactivity against murine CT26 colon carcinoma cells. Confocal live-cell imaging demonstrated its functional activity regarding the interaction with the target cells. We furthermore demonstrated the cytotoxicity of the released ML1 (I.E., After USL were treated with HIFU). The potent cytotoxicity (IC50 400 ng/ml; free ML1 IC50 345 ng/ml) was compared to non-triggered USL loaded with ML1. Our study shows that USL in combination with HIFU hold promise as trigger-sensitive nanomedicines for local delivery of macromolecular cytotoxins.

Engineering of a novel subnanomolar affinity fibronectin III domain binder targeting human programmed death-ligand 1.

The programmed death-ligand 1 (PD-L1) is a major checkpoint protein that helps cancer cells evade the immune system. A non-invasive imaging agent with rapid clearance rate would be an ideal tool to predict and monitor the efficacy of anti-PD-L1 therapy. The aim of this research was to engineer a subnanomolar, high-affinity fibronectin type 3 domain (FN3)-based small binder targeted against human PD-L1 (hPD-L1) present on tumor cells. A naive yeast G4 library containing the FN3 gene with three binding loop sequences was used to isolate high-affinity binders targeted to purified full-length hPD-L1. The selected binder clones displayed several mutations in the loop regions of the FN3 domain. One unique clone (FN3hPD-L1-01) with a 6x His-tag at the C-terminus had a protein yield of >5mg/L and a protein mass of 12kDa. In vitro binding assays on six different human cancer cell lines (MDA-MB-231, DLD1, U87, 293T, Raji and Jurkat) and murine CT26 colon carcinoma cells stably expressing hPD-L1 showed that CT26/hPD-L1 cells had the highest expression of hPD-L1 in both basal and IFN-γ-induced states, with a binding affinity of 2.38±0.26nM for FN3hPD-L1-01. The binding ability of FN3hPD-L1-01 was further confirmed by immunofluorescence staining on ex vivo CT26/hPD-L1 tumors sections. The FN3hPD-L1-01 binder represents a novel, small, high-affinity binder for imaging hPD-L1 expression on tumor cells and would aid in earlier imaging of tumors. Future clinical validation studies of the labeled FN3hPD-L1 binder(s) have the potential to monitor immune checkpoint inhibitors therapy and predict responders.

75P - Pulse mode irradiation regimen of PDT results in high progression free and overall survival in mice with model tumour

BackgroundPhotodynamic therapy (PDT) is one of actively developing modalities of cancer treatment. During PDT procedure systemically injected photosensitizer molecules are activated by laser irradiation in tumor location leading to generation of singlet oxygen which induces cytotoxic effect. In modern clinical practice PDT uses continuous wave irradiation. In such mode fast depletion of molecular (triplet) oxygen in tissue occurs leading to reduction of PDT efficiency. Previously we have shown that photodynamic treatment using pulse mode irradiation regimens could be more efficient in damaging tumor cells than standard PDT due to reoxygenation (Klimenko et. al., Photodiagnosis Photodyn Ther., 2016). In present study we have evaluated specially designed pulse mode PDT regimes on tumor model in vivo. MethodsPDT pulse mode irradiation regimens were designed using physics and mathematical modelling. BALB/c male mice were subcutaneous injected into right flanks with CT26 murine colon carcinoma cells. At day ten after inoculation mice were randomized into 3 groups with 10 animals in each (control group, PDT at continuous wave irradiation mode – CW group, PDT at pulse irradiation mode – PM group) and PDT was made. The RadachlorinⓇ photosensitizer and «Lahta-Milon» semiconductor laser (662nm) were used. After treatment the tumor size was estimated every two days. All experiments were performed in accordance with the animal ethics guidelines. ResultsWe have designed new pulse mode irradiation regimens of PDT. We have shown that antitumor efficiency of PDT at pulse irradiation mode is much better than one at standard continuous wave irradiation mode. Median survival after day of treatment was 14 days in control group, 16 days in CW group and 28 days in PM group. In PM group 5 animals had total regress of tumor and progression free survival till the end of experiment (100 days after treatment) compared with only 1 animal in CW group. Thus, we can suggest that overall survival should be much higher in PM group. ConclusionsWe have demonstrated that PDT using pulse mode irradiation regimens is much more effective that PDT using standard regimens and leads to higher progression free and overall survival in mice with CT26 colon carcinoma. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

Abstract 3202: A probody drug conjugate targeting CD166 (ALCAM) enhances preclinical antitumor activity of a probody therapeutic targeting PD-1

Abstract Immune checkpoint blockade therapies have been shown to induce potent and durable anti-tumor immunity in many cancer types. Nevertheless, not all patients benefit from immunotherapy, and immune-related adverse events remain a problem. Recently, it has been demonstrated that Antibody Drug Conjugates (ADCs) are not only capable of killing cancer cells but also can act to induce the immunogenic cell death of tumor cells as well as directly activate dendritic cells. These results provided a rationale to combine ADCs with immunotherapy to enhance the potential of immune checkpoint blockade therapies in a broader population of patients. CytomX Therapeutics has developed a new class of antibodies called Probody™ therapeutics, designed to widen the therapeutic window by minimizing binding to target in healthy tissue while being specifically activated in the tumor microenvironment (TME) by tumor-associated proteases. Probody technology has been evaluated in preclinical studies in several antibody formats, with efficacy and increased safety windows observed for Probody therapeutics targeting the PD-1 pathway, Probody drug conjugates (PDCs) targeting highly expressed tumor antigens, and T-cell engaging bispecific Probody therapeutics. Here we extend our evaluation of the Probody platform to the combination of CX-2009, an investigational PDC targeting human CD166, with an investigational Probody therapeutic targeting PD-1. To evaluate the anti-tumor activity of PDC CX-2009 in a syngeneic mouse model, human CD166 was overexpressed on the surface of the CT-26 murine colon carcinoma cell line. The combination treatment of CX-2009 with a surrogate mouse anti-PD-1 Probody molecule significantly inhibited tumor growth in human CD166 positive CT-26 tumor-bearing mice as compared to CX-2009 or anti-PD-1 Probody molecule alone. Tumor rejection is partially dependent on CD8+ T cells as illustrated by the evidence of a CD8+ memory T cell response in a re-challenge assay, and a reduced activity of CX-2009 alone or in combination with a mouse anti-PD-1 Probody molecule after CD8+ T cell depletion. The immunogenic potential of CX-2009 was further evaluated in multiple in vitro assays using human cancer cells and human PBMCs. In contrast to its cytotoxic activity towards CD166+ tumor cells, CX-2009 spares T cells and may enhance T cell priming. These preclinical data demonstrate the potential utility of a combination of PDC CX-2009 with a Probody therapeutic targeting the PD-1 pathway. Generally, these data highlight the potential to combine ADCs or PDCs with immune checkpoint blockade therapies. PROBODY is a trademark of CytomX Therapeutics, Inc. Citation Format: Erwan Le Scolan, Tiffany Tse, Michael Krimm, Will Garner, Hikmat Assi, Jennifer Razo, Laurie Wong, Kenneth Wong, Victoria Singson, Jennifer Leong, Linnea Diep, Jennifer Richardson, Siew Schleyer, Dylan Daniel, Marcia Belvin, Michael Kavanaugh. A probody drug conjugate targeting CD166 (ALCAM) enhances preclinical antitumor activity of a probody therapeutic targeting PD-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3202.

Dietary fructose-induced gut dysbiosis promotes mouse hippocampal neuroinflammation: a benefit of short-chain fatty acids

BackgroundWestern-style diets arouse neuroinflammation and impair emotional and cognitive behavior in humans and animals. Our previous study showed that a high-fructose diet caused the hippocampal neuroinflammatory response and neuronal loss in animals, but the underlying mechanisms remained elusive. Here, alterations in the gut microbiota and intestinal epithelial barrier were investigated as the causes of hippocampal neuroinflammation induced by high-fructose diet.ResultsA high-fructose diet caused the hippocampal neuroinflammatory response, reactive gliosis, and neuronal loss in C57BL/6N mice. Depletion of the gut microbiota using broad-spectrum antibiotics suppressed the hippocampal neuroinflammatory response in fructose-fed mice, but these animals still exhibited neuronal loss. Gut microbiota compositional alteration, short-chain fatty acids (SCFAs) reduction, intestinal epithelial barrier impairment, NOD-like receptor family pyrin domain-containing 6 (NLRP6) inflammasome dysfunction, high levels of serum endotoxin, and FITC-dextran were observed in fructose-fed mice. Of note, SCFAs, as well as pioglitazone (a selective peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist), shaped the gut microbiota and ameliorated intestinal epithelial barrier impairment and NLRP6 inflammasome dysfunction in fructose-fed mice. Moreover, SCFAs-mediated NLRP6 inflammasome activation was inhibited by histamine (a bacterial metabolite) in ex vivo colonic explants and suppressed in murine CT26 colon carcinoma cells transfected with NLRP6 siRNA. However, pioglitazone and GW9662 (a PPAR-γ antagonist) exerted no impact on SCFAs-mediated NLRP6 inflammasome activation in ex vivo colonic explants, suggesting that SCFAs may stimulate NLRP6 inflammasome independently of PPAR-γ activation. SCFAs and pioglitazone prevented fructose-induced hippocampal neuroinflammatory response and neuronal loss in mice. Additionally, SCFAs activated colonic NLRP6 inflammasome and increased DCX+ newborn neurons in the hippocampal DG of control mice.ConclusionsOur findings reveal that gut dysbiosis is a critical factor for a high-fructose diet-induced hippocampal neuroinflammation in C57BL/6N mice possibly mediated by impairing intestinal epithelial barrier. Mechanistically, the defective colonic NLRP6 inflammasome is responsible for intestinal epithelial barrier impairment. SCFAs can stimulate NLRP6 inflammasome and ameliorate the impairment of intestinal epithelial barrier, resulting in the protection against a high-fructose diet-induced hippocampal neuroinflammation and neuronal loss. This study addresses a gap in the understanding of neuronal injury associated with Western-style diets. A new intervention strategy for reducing the risk of neurodegenerative diseases through SCFAs supplementation or dietary fiber consumption is emphasized.

PH-sensitive polymeric nanoparticles of quercetin as a potential colon cancer-targeted nanomedicine

Quercetin (QCT) is an abundant plant polyphenol with demonstrated efficacy in several diseases including colon cancer. Herein we have developed polymeric nanoparticles (NPs) of QCT based on the pH-sensitive polymer Eudragit® S100 to achieve colon pH-specific drug release following oral administration. NPs were prepared by the nanoprecipitation technique and showed a mean diameter of 66.8 nm and a partially negative surface charge of −5.2 mV. NPs contained on average 2.2% w/w QCT at an encapsulation efficiency of 41.8%. IR spectroscopy and differential scanning calorimetry (DSC) both revealed the presence of intermolecular interactions, most likely H-bonding, between QCT and Eudragit® S100, which likely contributed to drug loading. DSC also indicated that the drug was present in the NPs in an amorphous state, which was further confirmed by X-ray diffraction. In vitro release testing showed a delay in drug release in acidic pH, but complete release within 24 h at pH 7.2. A cytotoxicity assay was performed on CT26 murine colon carcinoma cells, where QCT-loaded NPs displayed significantly higher potency (IC50 = 0.8 μM) than free QCT (IC50 = 65.1 μM). Our findings present a promising nanomedicine for colon-targeted delivery of QCT in diseases such as colon cancer.

Thermosensitive liposomes for triggered release of cytotoxic proteins

Lysolipid-containing thermosensitive liposomes (LTSL) are clinically-relevant drug nanocarriers which have been used to deliver small molecule cytostatics to tumors in combination with local hyperthermia (42 °C) to trigger local drug release. The objective of this study was to investigate the feasibility of LTSL for encapsulation and triggered release of macromolecular drugs such as plant-derived cytotoxins. As therapeutic protein we used Mistletoe lectin-1 (ML1) - a ribosome-inactivating protein with potent cytotoxic activity in tumor cells.Model macromolecules (dextrans, albumin) and ML1 were encapsulated in small unilamellar LTSL with varying lipid compositions by the thin film hydration method and extrusion. LTSLs showed molecular weight dependent heat-triggered release of the loaded cargo. The most promising composition, ML1 formulated in LTSL composed of 86:10:4 %mol DPPC:MSPC:DSPE-PEG2000, was further studied for bioactivity against murine CT26 colon carcinoma cells. Confocal live-cell imaging showed uptake of released ML1 after mild hyperthermia at 42 °C, subsequently leading to potent cytotoxicity by LTSL-ML1. Our study shows that LTSL in combination with localized hyperthermia hold promise as local tumor delivery strategy for macromolecular cytotoxins.

A novel herbal formula, SGE, induces endoplasmic reticulum stress-mediated cancer cell death and alleviates cachexia symptoms induced by colon-26 adenocarcinoma.

Cachexia in cancer patients, characterized by marked involuntary weight loss and impaired physical function, is associated with a poor prognosis in response to conventional treatment and with an increase in cancer-related mortality. Prevention of skeletal muscle loss under cancer-induced cachexia via inhibition of pro-cachectic factors, as well as a reduction in tumor mass, has been considered reasonable pharmacological and nutritional interventions to treat cancer patients. In this study, we constructed a novel herbal formula, SGE, which contains Ginseng Radix alba, Atractylodis Rhizoma alba, and Hoelen, examined its anti-cancer and anti-cachexia efficacies. In in vitro experiments, SGE induced death of CT-26 murine colon carcinoma cells via endoplasmic reticulum stress, and suppressed the production of inflammatory cytokines in Raw 264.7 murine macrophage-like cells. In addition, SGE treatment attenuated CT-26-induced C2C12 skeletal muscle cell atrophy as well as CT-26-induced reduction in lipid accumulation in 3T3-L1 adipocyte. In CT-26 tumor-bearing mice, daily oral administration of 10 and 50 mg/kg SGE remarkably attenuated the cachexia-related symptoms, including body weight and muscle loss, compared with saline treatment, while food intake was not affected. These data collectively suggest that SGE is beneficial as an anti-cancer adjuvant to treat cancer patients with severe weight loss.

Abstract B148: Activity of the TAM kinase-targeting compound, SLC-391, is mediated by the engagement of the immune system in CT-26 syngeneic mouse model

Abstract Overexpression of TAM family receptor tyrosine kinases such as Axl has been reported in numerous types of human cancer, and found to correlate with tumor progression and prognosis, metastasis, and drug resistance. Aside from the role in cell growth and survival, TAM kinases have long been recognized for their immunosuppressive activity as well. Hence, downregulation of their activity is expected to unleash antitumor immunity in the tumor microenvironment. As one of the several TAM-targeting small-molecule inhibitors identified, SLC-391 displays a relatively strong activity against Axl, as evidenced by the reductions of phosphotransferase activity in radiometric biochemical assay and the level of Axl Y779 phosphorylation in the cell-based assay. Contradictorily, proliferation of CT-26 murine colon carcinoma cells seemed to be unaffected by the compound in the thymidine incorporation assay with an IC50 of ~10 μM. Interestingly, SLC-391 inhibited CT-26 tumor growth by 37% in a 15-day efficacy study in which the compound was administered at 50 mg/kg p.o.. In comparison, a PD-1 antibody delayed tumor growth by 27%. Tumor-infiltrating lymphocyte phenotyping revealed increases in the number of NK cells and the ratio of M1/M2-polarized macrophages in SLC-391 treatment group, followed by the rise of CD8+ T/Treg ratio and reduction in immunosuppressive myeloid cells. This is indicative of sequential engagement and stimulation of proinflammatory innate immune response and adaptive immune response. In addition, a synergistic antitumor effect was observed when the anti-PD-1 insensitive CT-26 syngeneic model was treated with a combination of SLC-391 and an anti-PD-1 antibody and the overall survival rate of the combination group was prolonged dramatically in comparison with the vehicle control group. To summarize, the antitumor activity of SLC-391 is at least in part mediated by reversing the immunosuppressive tumor microenvironment in CT-26 colon carcinoma model. Citation Format: Shenshen Lai, Rick Li, Paromita Raha, Yuxiang Hu, Jun Yan, Hong Zhang, Anthony Marotta, Zaihui Zhang. Activity of the TAM kinase-targeting compound, SLC-391, is mediated by the engagement of the immune system in CT-26 syngeneic mouse model [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B148.

Abstract 4896: Role of CDK8 in colon cancer hepatic metastasis

Abstract About half of all colon cancer patients will develop liver metastases and the 5-year survival for these patients is less than 13%, making colon cancer the second most lethal cancer worldwide. Cyclin dependent kinase 8 (CDK8), which regulates transcription but not cell cycle progression, has been identified as an oncogene amplified in many colon cancers. CDK8 acts as a positive mediator of oncogenic transcription pathways regulated by Wnt/beta-catenin and TGF-beta, both of which are strongly associated with tumor metastasis. In a colon cancer liver metastasis model based on splenic injection of CT26 murine colon carcinoma cells, treatment with Senexin B, a highly selective small-molecule inhibitor of CDK8 and its paralog CDK19, strongly inhibited metastatic growth in the liver and prolonged the survival of mice with hepatic metastases. In contrast to the effect on liver metastasis, CDK8 inhibition had little or no effect on cell growth in culture or at primary tumor sites. Hepatic metastasis was inhibited to the same extent when Senexin B was administered starting from the time of tumor injection or only during a later part of the study, suggesting that the drug affected metastatic growth in the liver rather than just initial colonization. Liver metastasis was similarly decreased by CDK8 knockdown in CT26 cells, suggesting that the anti-metastatic activity of Senexin B was due at least in part to its effect on tumor cells. Transcription profiling indicated that CDK8 inhibition by shRNA or Senexin B strongly decreased the expression of metastasis-associated metalloproteinases MMP 13, MMP10, and MMP3 and at the same time drastically increased the expression of TIMP3, a metalloproteinase inhibitor. TIMP3 overexpression in CT26 cells, like CDK8 inhibition, decreased hepatic metastasis. CDK8 inhibition also blocked TGF-beta or Wnt3a-stimulated transwell Matrigel invasion of CT26 cells in vitro. Knockdown of beta-catenin in CT26 cells decreased the expression of MMP3 and MMP13, while knockdown of SMAD4 (transcriptional mediator of TGF-beta pathway) induced TIMP3 expression. Beta-catenin knockdown decreased both the primary tumor growth in the spleen and metastatic growth in the liver, whereas SMAD4 knockdown, like that of CDK8, selectively inhibited liver metastasis. Senexin B also suppressed hepatic metastasis after splenic injection of human HCT116 colon carcinoma cells. In summary, our data identified CDK8 as a key transcriptional regulator of colon cancer metastatic growth in the liver, interacting with TGF-beta and Wnt/beta-catenin pathways and regulating the expression of MMPs and Timp3. CDK8/19 inhibitors, which are now entering clinical trials, may be effective for the treatment of hepatic metastasis of colon cancer. Citation Format: Jiaxin Liang, Mengqian Chen, Mythreye Karthikeyan, M. Marjorette Pena, Daniel Hughes, Vimala Kaza, Chang-Uk Lim, Eugenia Broude, Igor B. Roninson. Role of CDK8 in colon cancer hepatic metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4896. doi:10.1158/1538-7445.AM2017-4896