Murine Colon Carcinoma Cells Research Articles

Abstract 639: Targeting TET3 potentiates an effective anti-tumor immune response after irradiation

Abstract The benefits of radiotherapy (RT) have long been appreciated as limited by formation and repair of DNA double-strand breaks (DSBs) in tumor cells, but recent understanding has identified a key role for RT and DNA damage in promoting inflammation that drives anti-tumor immune response. While chromosomal DSBs indeed directly limit cancer cell survival and proliferation, RT-induced damage leads to cytosolic DNA that activates cGAS/STING/IRF3 signaling and drives IFNα/β expression, recruiting cytotoxic T and NK cells to shrink tumors. In turn, along with DSB repair, another determinant of RT resistance is rebound immunosuppression. Here, IFNγ released by the infiltrating lymphocytes activates JAK/STAT to induce interferon-stimulated genes (ISGs) including PD-L1 that can reduce tumor inflammation and restore growth. Though combining PD-1/PD-L1 blockade with RT is sufficient to block this adaptive response in mice, the lack of benefit to patients suggests the need to more broadly target immunosuppressive ISG expression. Targeting IFNγ signaling by blocking JAK/STAT may limit immunosuppressive ISG expression but will impair T and NK cytotoxicity. Looking downstream, blocking JAK/STAT-dependent ISG promoter CpG demethylation by Ten Eleven Translocation (TET) dioxygenase enzymes may prevent PD-L1 expression without affecting cytotoxicity. In this study, we disrupted TET activity with small-molecule inhibitors and CRISPR RNP knockouts (KO) to evaluate effects on radiation response in vitro and in tumors. As predicted, TET inhibitors blocked PD-L1 induction in irradiated CT26 murine colon carcinoma cells. Assaying TET1, 2 and/or 3 KO CT26 cells for PD-L1 induction identified TET3 as the critical mediator. TET3 KO cells also exhibited slower DSB repair after irradiation, associated with markedly increased ssDNA resection and cytosolic DNA. The irradiated TET3 KO cells also displayed enhanced IFNα/β expression, suggesting intact cGAS/STING/IRF3 signaling. While TET3 KO CT26 cells formed tumors in syngeneic BALB/c mice much like CT26 controls, RT produced greater NK cell infiltrates by one week and increased tumor elimination by two weeks. TET3 KO 4T1 mammary carcinoma cells formed orthotopic tumors in BALB/c mice but produced fewer lung metastases compared to controls. In conclusion, TET3 may offer an attractive, druggable target for radiosensitization by slowing DSB repair, enhancing tumor inflammation, and blocking immunosuppressive ISG expression. Citation Format: Sera Averbek, Stephen J. Kron. Targeting TET3 potentiates an effective anti-tumor immune response after irradiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 639.

Colon cancer exosome-associated HSP90B1 initiates pre-metastatic niche formation in the liver by polarizing M1 macrophage into M2 phenotype

BackgroundColorectal cancer (CRC) frequently metastasizes to the liver, worsening patient outcomes. The formation of a pre-metastatic niche (PMN) is essential for this process, but how the primary colon tumor orchestrates the PMN formation remains unclear.MethodsThis study investigated the role of CRC-derived exosomes using CT-26 murine colon carcinoma cells. The effects of these exosomes on immune cells, specifically M1 macrophage polarization and CD8 + T cell viability, were assessed. HSP90B1 expression in CT-26-derived exosomes was analyzed to understand its contribution to PMN formation. HSP90B1 silencing experiments were conducted to evaluate its impact on immunosuppressive PMN creation and liver metastasis. Patient blood samples were also examined to correlate exosomal HSP90B1 levels with CRC progression.ResultsExosomes from CT-26 cells were found to polarize M1 macrophages into an M2 phenotype and decrease CD8 + T cell viability, promoting liver metastasis. High expression of HSP90B1 in CT-26 cell-derived exosomes was identified as a key factor in inducing M2 macrophage polarization and creating an immunosuppressive PMN. Silencing HSP90B1 significantly inhibited the exosome-mediated formation of the immunosuppressive PMN and reduced liver metastasis. Furthermore, elevated levels of HSP90B1 in patient-derived exosomes were associated with advanced CRC and poorer prognosis.ConclusionsCRC-derived exosomes promote liver metastasis by forming an immunosuppressive PMN through HSP90B1. Targeting HSP90B1 in CRC exosomes may offer a new therapeutic strategy to prevent liver metastasis and improve patient outcomes.

Perfluorohexane Emulsions Induce Macrophage-Stimulating Effects through iNOS Expression.

Despite advances in cancer immunotherapy, efficacy has been limited to a subset of patients, highlighting the need for continued development of innovative therapeutic approaches. Perfluorocarbon-filled (PFC) particles, due to unique physicochemical properties, biological stability, and quantifiability as 19F-MRI tracers, have been intensely investigated as in vivo macrophage imaging agents. Despite this, little is known about the effect of PFC particle uptake on macrophage behavior. Here, phospholipid-stabilized perfluorohexane (PFH) nanodroplets (NDs) were used to treat bone-marrow-derived macrophages (BMDMs) in vitro and tumor-implanted mice in vivo. Physiological response was assessed by using biochemistry, flow cytometry, fluorescence imaging, and tumor measurements. The incubation of alternatively-activated (M2) BMDMs with PFH NDs led to a dose- and time-dependent increase of iNOS expression but not that of other common M1 or M2 markers. PFH ND-induced iNOS expression was further enhanced when treated M2 BMDMs were co-cultured with MC38 murine colon carcinoma cells, resulting in more effective tumoral cell apoptosis. Similarly, intratumoral injection of PFH NDs in a murine colon carcinoma model led to increased iNOS expression within the tumors and caused a substantial decrease in tumor size. This size reduction was also unexpectedly accompanied by the formation of peritumoral gas pockets, which, when aspirated, abrogated tumoral effects. Conversely, intratumoral injection of emulsions made with high-boiling-point (BP = 142 °C) perfluorooctyl bromide (PFOB) did not produce gas pockets or inhibit tumor growth. Our data collectively show the immunogenic potential of PFH NDs through iNOS expression and promote the potential development of theranostic PFC-based platforms.

MTT assay-based evaluation of live, heat-killed, and cell-free supernatants of probiotic bacteria on CT-26 murine colon carcinoma cells

MTT assay-based evaluation of live, heat-killed, and cell-free supernatants of probiotic bacteria on CT-26 murine colon carcinoma cells

Antitumor efficacy of intermittent low‐dose erlotinib plus sulindac via MHC upregulation and remodeling of the immune cell niche

A previously reported clinical trial in familial adenomatous polyposis (FAP) patients treated with erlotinib plus sulindac (ERL + SUL) highlighted immune response/interferon‐γ signaling as a key pathway. In this study, we combine intermittent low‐dose ERL ± SUL treatment in the polyposis in rat colon (Pirc) model with mechanistic studies on tumor‐associated immune modulation. At clinically relevant doses, short‐term (16 weeks) and long‐term (46 weeks) ERL ± SUL administration results in near‐complete tumor suppression in Pirc colon and duodenum (p < 0.0001). We identify a low‐dose threshold for significant antitumor activity in Pirc rats given SUL at 125 ppm in the diet plus ERL at 5 mg/kg body weight via twice‐weekly oral gavage (SUL125 + ERL5 × 2). Longitudinal analyses show diminished expression of MHC class I and II genes in polyps larger than Grade 5, a novel finding in the Pirc model. Treatment with ERL ± SUL upregulates the corresponding MHC and immune‐associated factors in a subset of Pirc colon polyps, Pirc tumor cell lines, murine colon carcinoma cells, and FAP patient‐derived organoids, with Nlrc5 playing a critical role in this effect. Imaging mass cytometry reveals that SUL125 + ERL5 × 2 increases tumor‐associated Cd4+ T cells by ~2.6‐fold (p < 0.05), with no apparent effect on Cd8+ T cells. The treatment also increases tumor‐associated Cd68+ cells (p < 0.05) and decreases Foxp3+ (p < 0.01) and Arg1+ (p < 0.05) cells. Thus, intermittent low‐dose ERL + SUL treatment enhances tumor‐associated MHC expression and remodels the immune cell niche toward a more permissive “helper” immune microenvironment. We conclude that early immune‐interception strategies targeting interferon‐γ signaling may benefit FAP patients at drug doses below the clinical standard of care.

A77 THE INFLUENCE OF IRON SUPPLEMENTATION IN EARLY LIFE ON COLORECTAL CANCER PROGRESSION

Abstract Background During the first years of life, the immune system develops simultaneously with the gut microbiota, and it has been previously shown that perturbations to gut microbiota development can lead to altered immune phenotypes later in life. One factor that may influence the gut microbiota in early life, and therefore immune development, is iron supplementation. Aims We aim to evaluate how iron supplementation in early life affects immune system development and therefore cancer progression in adulthood. Methods BALB/c mice were given either an iron sufficient or an iron excess diet beginning at weaning until adulthood at 8 weeks of age. All mice were then placed on the iron sufficient diet for two weeks prior to beginning the experimental model in order to establish the effect of iron only during the early life period. Mice were then injected subcutaneously with the murine colon carcinoma cell line CT-26. Results Mice that recieved iron supplementation in early life had significantly higher levels of iron in both the liver and spleen, indicating that this diet was successful in increasing iron levels. Furthermore, mice given iron supplementation had significantly more sebaceous glands per mm ear tissue than mice given the iron sufficient diet. Sebaceous glands are structures in the skin important for coordination of the innate immune response and regulation of the skin microbiota. We next measured several cytokines by ELISA. Mice supplemented with iron had significantly lower levels of interleukin (IL)-4, IL-10, and interferon (IFN)-γ. Conclusions Considering that mice given the iron excess diet had significantly altered skin immune structures and significantly decreased basal cytokine levels in ear tissue, we conclude that iron supplementation in early life modulates immune system development. Next, we will evaluate how iron supplementation in early life affects colorectal cancer development and progression. Funding Agencies CIHRFRQS, NSERC

Sesquiterpene lactones from Tithonia diversifolia with ferroptosis-inducing activities

Sesquiterpene lactones from Tithonia diversifolia with ferroptosis-inducing activities

Abstract 6647: Established 3D tumor-spheroid co-culture models demonstrate macrophage plasticity and unveil potential supportive roles of macrophages in the T cell-tumor-macrophage crosstalk post radiation therapy

Abstract Ionizing radiation therapy (RT) has been characterized as an immunogenic event that in some tumors results in cell-death mediated activation of innate inflammatory and immunostimulatory mediators. These inflammatory mediators in turn modulate lymphocyte effector function in the tumor environment that can contribute to radiation-mediated control of tumors. We aim to model these interactions ex vivo, to identify the critical signals regulating immune function. We demonstrate that it is necessary to establish a three-dimensional model for crosstalk between tumor cells and immune cells to recapitulate myeloid and T cell responses to radiation. We have established 3D tumor spheroid co-culture models using murine MC38 colon carcinoma and Panc02-SIY pancreatic carcinoma cell lines with bone-marrow derived macrophages (BMDM). The spheroid cultures were exposed to 12 Gy RT and maintained in culture over a period of 5 days. Analyses were done using live-cell imaging and flow cytometry. Our findings demonstrate a decrease in hypoxia post RT, and exposure to RT increased the phagocytosis of dying cancer cells by macrophages. This was followed by a significant increase in CD80 and CD86 expression on the surface of macrophages in co-cultures on day 3 and day 4 post RT. These data matched our analyses of tumors treated in vivo with radiation and analyzed on day 4 post RT. In addition to RT-mediated upregulation of costimulatory molecules on macrophages, we also observed an increase in PD-L1 expression that may also impact T cell responses. To test T cell function in the 3D model, antigen-specific T cells were added to the Panc-02-SIY and BMDM spheroid co-cultures, which resulted in enhanced T cell proliferation in RT-treated groups. To assess the mechanism of macrophage activation in co-cultures, we evaluated HMGB1 as an innate adjuvant that may cause TLR4-mediated macrophage activation; however, the pattern of activation did not match that of RT. The involvement of the nucleic acid sensing cGAS-STING pathway was assessed by using BMDM from STING knockout (KO) mice in the 3D co-cultures. Similar upregulation of CD80 and CD86 were observed on STING KO macrophages in 3D co-cultures on day 4 post RT, indicating the observed phenomena to be independent of STING signaling. Ongoing studies aim to decrypt the innate downstream signaling pathways involved in RT-mediated polarization of macrophages so as to identify potential targeted therapies for tumor-associated macrophages, and also translate this to patient tumors. Citation Format: Aanchal Preet Kaur, Alejandro F. Alice, Megan R. Potuznik, Gwen Kramer, Jason Baird, David J. Friedman, Marka R. Crittenden, Michael J. Gough. Established 3D tumor-spheroid co-culture models demonstrate macrophage plasticity and unveil potential supportive roles of macrophages in the T cell-tumor-macrophage crosstalk post radiation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6647.

Abstract 5276: Immunomodulatory activity of intermittent low-dose erlotinib plus sulindac: Implications for hereditary and sporadic colorectal cancer

Abstract A once-weekly optimized dosing regimen of erlotinib (ERL) in the polyposis in rat colon (Pirc) model [1] was a reliable predictor of antitumor efficacy in familial adenomatous polyposis (FAP) patients [2]. Pirc rats are increasingly used as a translational tool for FAP studies. Based on transcriptomic data from FAP patients receiving ERL plus sulindac (SUL) vs. placebo [3], we determined the timing of changes in interferon-γ signaling in Pirc adenomas, while performing additional dose titration. In rats that were given ERL administered at 5 mg per kilogram of body weight through oral gavage (two times a week) and that received a diet containing 125 parts per million of SUL, a regimen referred to as SUL125+ERL5x2, significant suppression of tumor growth was observed. This combination represented half of the standard of care SUL dose and about one-quarter of the ERL dose in FAP patients. In adenomas collected after one year of treatment from SUL125+ERL5x2 treated rats, the expression of genes related to the major histocompatibility complex (MHC) class I (β2m, Cnx, Psmb8 and Tap1) and MHC class II (RT1-A2, Cd74, RT-1Bb, Cd74, and Ciita) was increased, compared to vehicle controls, excluding a subset of adenomas that remained resistant. Through the use of multiplex mass cytometry (CyTOF), an increase in tumor-infiltrating CD4+ T cells was observed in adenomas from the SUL125+ERL5x2 treatment group. Administration of single or combined agents increased CD68+ cells and reduced the presence of Foxp3+ and Arg1+ cells in Pirc adenomas. The natural history of adenomatous colon polyps indicated an increase in MHC gene expression as tumors increased in size; however, this trend reversed markedly in fully occluding lesions. Additionally, expression of MHC-related factors increased in Pirc colon adenoma and murine colon carcinoma cells treated with ERL±SUL, resulting in enhanced CD8+ T-cell activation and IL-2 secretion. In conclusion, treatment with intermittent low doses of ERL±SUL increased MHC gene expression and induced changes in the immune cell component in the tumor microenvironment of Pirc rat adenomas. A subset of non-responsive adenomas could benefit from additional immunopreventive approaches, with implications for possible clinical applications in both hereditary and sporadic colorectal cancer.

High efficacy of particle beam therapies against tumors under hypoxia and prediction of the early stage treatment effect using 3'-deoxy-3'-[18F]fluorothymidine positron emission tomography

ObjectiveCompared with radiation therapy using photon beams, particle therapies, especially those using carbons, show a high relative biological effectiveness and low oxygen enhancement ratio. Using cells cultured under normoxic conditions, our group reported a greater suppressive effect on cell growth by carbon beams than X-rays, and the subsequent therapeutic effect can be predicted by the cell uptake amount of 3'-deoxy-3'-[18F]fluorothymidine (18F-FLT) the day after treatment. On the other hand, a hypoxic environment forms locally around solid tumors, influencing the therapeutic effect of radiotherapy. In this study, the influence of tumor hypoxia on particle therapies and the ability to predict the therapeutic effect using 18F-FLT were evaluated.MethodsUsing a murine colon carcinoma cell line (colon 26) cultured under hypoxic conditions (1.0% O2 and 5.0% CO2), the suppressive effect on cell growth by X-ray, proton, and carbon irradiation was evaluated. In addition, the correlation between decreased 18F-FLT uptake after irradiation and subsequent suppression of cell proliferation was investigated.ResultsTumor cell growth was suppressed most efficiently by carbon-beam irradiation. 18F-FLT uptake temporarily increased the day after irradiation, especially in the low-dose irradiation groups, but then decreased from 50 h after irradiation, which is well correlated with the subsequent suppression on tumor cell growth.ConclusionsCarbon beam treatment shows a strong therapeutic effect against cells under hypoxia. Unlike normoxic tumors, it is desirable to perform 18F-FLT positron emission tomography 2–3 days after irradiation for early prediction of the treatment effect.Graphical

High Salt Diet Exacerbates Intestinal Radiotoxicity by Promoting Intestinal Epithelial Barrier Dysfunction after RT

High Salt Diet Exacerbates Intestinal Radiotoxicity by Promoting Intestinal Epithelial Barrier Dysfunction after RT

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

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

Synergistic Effect of Ginsenoside Rh2 Combines with Ionizing Radiation on CT26/luc Colon Carcinoma Cells and Tumor-Bearing Animal Model.

The local tumor control rate of colon cancer by radiotherapy is unsatisfactory due to recurrence and radioresistance. Ginsenoside Rh2 (Rh2), a panoxadiol saponin, possesses various antitumor effects. CT26/luc murine colon carcinoma cells and a CT26/luc tumor-bearing animal model were used to investigate the therapeutic efficacy of Rh2 combined with ionizing radiation and the underlying mechanisms. Rh2 caused cell cycle arrest at the G1 phase in CT26/luc cells; however, when combined with ionizing radiation, the cells were arrested at the G2/M phase. Rh2 was found to suppress the activity of NF-κB induced by radiation by inhibiting the MAPK pathway, consequently affecting the expression of effector proteins. In an in vivo study, the combination treatment significantly increased tumor growth delay time and overall survival. Furthermore, the combination treatment significantly reduced NF-κB and NF-κB-related effector proteins, along with PD-1 receptor expression. Additionally, Rh2 administration led to increased levels of interleukin-12, -18, and interferon-γ in the mice's sera. Importantly, biochemical analysis revealed no toxicities associated with Rh2 alone or combined with radiation. The combination of Rh2 with radiation may have potential as an alternative to improve the therapeutic efficacy of colorectal cancer.

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.

A Chinese Medicine, Huajie Xiaoliu Formula, Enhances the Anti-Colon Cancer Effect of Tegafur, Gimeracil, and Oteracil Potassium Capsules Through Bcl-2/Bax Signaling Pathway

Research Objective This study was aimed to determine the main ingredients of Huajie Xiaoliu Formula (HJF) and investigate the anti-colon cancer effect of its combination with Tegafur, Gimeracil, and Oteracil Potassium Capsules (S-1) in vivo as well as to preliminarily explore its possible mechanism. Materials and Methods The chemical composition of HJF was determined by ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). The murine colon carcinoma cell (CT 26.WT) subcutaneous xenograft model of colon cancer mice was established to evaluate the in vivo anti-colon cancer effect of HJF. Evaluation of pathological changes in tumor tissue was evaluated by hematoxylin–eosin staining. Enzyme-linked immunosorbent assay (ELISA) was used to measure the expressions of interleukin-1β (IL-1β), inflammatory cytokines interleukin (IL-6), and tumor necrosis factor-α (TNF-α) in mice serum. Immunohistochemistry was used to evaluate B cell lymphoma-2 (Bcl-2), Bax, and Ki67 protein expression in tumor tissue. Results Twenty chemicals in HJF were identified by UPLC-QTOF-MS. In vivo experiments showed that HJF has obvious inhibitory effects on the subcutaneous xenograft model of colon cancer mice. Results of ELISA showed HJF is able to increase mice body weight, inhibit tumor growth, and reduce the serum levels of IL-1β and IL-6 along with TNF-α. Immunohistochemistry results demonstrated that HJF can significantly inhibit the levels of Bax, Bcl-2, and Ki67 in mice with colon cancer transplant tumors. Furthermore, the combination of HJF and S-1 demonstrated a more significant antitumor effect than any other group in vivo. Conclusions Huajie Xiaoliu Formula is effective in CT 26.WT subcutaneous xenograft model of colon cancer mice by inhibiting tumorigenesis, metastasis, and angiogenesis through the Bcl-2/Bax signaling pathway, resulting in anti-colorectal tumor effects. Huajie Xiaoliu Formula provides a strong theoretical basis for its clinical use and also provides a basis for further research.

Abstract 4899: Inhibition of murine tumor growth by decitabine is correlated with enhanced expression of the mouse mammary tumor virus

Abstract The purpose of this study is to clarify the mechanisms of the antineoplastic effect of decitabine (DAC), a DNA methyltransferase inhibitor. We previously reported that DAC inhibited the proliferation of the 4T1 mammary cancer cell line in vitro while inhibiting MMTV env and pol expression in the same cells. Here we present findings in vivo using two murine tumor models. We inoculated 4T1 cells into BALB/c mice from which the cell line was derived. In addition, we inoculated the murine colon carcinoma cell line, MC38, into C57BL/6 mice, the mouse strain of its origin. We treated the mice with DAC when tumors became palpable. DAC inhibited tumor growth in both tumor models and inhibited metastasis of 4T1 cells into the lungs. Quantitative PCR detected elevated expression of MMTV genes in the tumor tissues of DAC-treated mice in both models. The levels of MMTV env RNA in tumor tissues were negatively correlated with tumor mass in both models, so were the levels of the MMTV Env protein in 4T1 tumors. DAC also significantly mitigated tumor-induced splenomegaly. Hepatotoxicity of DAC was observed in C57BL/6 mice. Our data suggest the possibility that decitabine inhibits tumor growth in vivo and in vitro via different mechanisms. The findings also support the current understanding of decitabine upregulating endogenous retroviruses (ERVs) which subsequently activate an interferon response. The negative correlation between tumor mass and MMTV Env protein expression suggests a possible role of ERV proteins serving as tumor-associated antigens and decitabine enhancing adaptive immunity against cancer by stimulating ERV expression on tumor cells. Further studies of the interaction between decitabine and MMTV using immunodeficient mice may help us understand the possible involvement of adaptive immunity in the pharmacodynamics of decitabine as well as the role of ERVs in tumor development. Citation Format: Jieyu Zhang, Savannah Higgins, Riley Smith, Tania Reginald, Andrew Qi, Jiayi Li, Anna King, Yingguang Liu. Inhibition of murine tumor growth by decitabine is correlated with enhanced expression of the mouse mammary tumor virus. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4899.

Macrophage STING signaling promotes NK cell to suppress colorectal cancer liver metastasis via 4-1BBL/4-1BB co-stimulation

Background and aimsMacrophage innate immune response plays an important role in tumorigenesis. However, the role and mechanism of macrophage STING signaling in modulating tumor microenvironment to suppress tumor growth at...

Effects of Iron on Efficacy of Photodynamic Therapy Using Photolon in a Mouse Model of CT26 Colon Cancer

Photodynamic therapy (PDT) -a minimally invasive anti-cancer therapy-is undergoing experimental studies to increase its anti-cancer effects. This study investigated the influence of iron on the anti-cancer effects of PDT. PDT was performed in a cancer-bearing mouse model, which was created by using a murine colon carcinoma (CT26) cell line after administration of Photolon and iron. Tumor volume and the results of TdT-mediated dUTP-biotin nick end labeling (TUNEL), 8-OHdG, and TBARS assays were used to measure anti-cancer effect. On day 14, tumor volume had increased by 49% in the PDT group and decreased by 72% in the iron+PDT group. The percentage of TUNEL-positive cells in tumor tissues was 45% in the PDT group and 69% in the iron+PDT group, suggesting that the proportion of TUNEL-positive cells had increased in the iron+PDT group. The 8-OHdG content in tumor tissues was 33% higher in the iron+PDT group than in the PDT group. The TBARS content in tumor tissues was 46% higher in the iron+PDT group than in the PDT group. Iron enhances the anti-cancer effect of PDT using Photolon, most likely by increasing oxidative damage.

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

IGF1R and HIF-1α Gene Silencing Inhibits Cancer Cell Growth

Background: According to several studies, hypoxia-inducible factor-1α (HIF-1α) and insulin-like growth factor 1 receptor (IGF1R) promote cancer progression and drug resistance. The overexpression of IGF1R and HIF-1 α is observed in various cancers, including breast and colon cancers. Thus, we tried to inhibit the progression of tumor cells by blocking IGF1R and HIF-1α. Methods: This study used Lipofectamine to transfect small interfering RNAs (siRNAs) into tumor cells. We treated murine mammary carcinoma (4T1) and murine colon carcinoma (CT26) cells with anti-IGF1R and anti-HIF-1 siRNAs. The real-time polymerase chain reaction (PCR) assay studied the impact of siRNA transfection on the mRNA levels of affected factors. Moreover, the viability of cancer cells was investigated by the MTT assay. Results: The investigations demonstrated that the mRNA levels of IGF1R and HIF-1α strongly reduced in tumor cell lines following siRNA transfection. Moreover, silencing IGF1R and HIF-1 additively downregulated cell viability in cancer cell lines. Conclusion: These findings imply that cancer combination therapy based on IGF1R and HIF-1α targeting may be a novel promising approach for the immunotherapy of breast and colorectal cancers; however, more study is required.