Murine Colorectal Cancer Cell Research Articles

Atypical chemokine receptor 2 expression is directly regulated by hypoxia inducible factor-1 alpha in cancer cells under hypoxia

Lack of significant and durable clinical benefit from anti-cancer immunotherapies is partly due to the failure of cytotoxic immune cells to infiltrate the tumor microenvironment. Immune infiltration is predominantly dependent on the chemokine network, which is regulated in part by chemokine and atypical chemokine receptors. We investigated the impact of hypoxia in the regulation of Atypical Chemokine Receptor 2 (ACKR2), which subsequently regulates major pro-inflammatory chemokines reported to drive cytotoxic immune cells into the tumor microenvironment. Our in silico analysis showed that both murine and human ACKR2 promoters contain hypoxia response element (HRE) motifs. Murine and human colorectal, melanoma, and breast cancer cells overexpressed ACKR2 under hypoxic conditions in a HIF-1α dependent manner; as such overexpression was abrogated in melanoma cells expressing non-functional deleted HIF-1α. We also showed that decreased expression of ACKR2 in HIF-1α-deleted cells under hypoxia was associated with increased CCL5 levels. Chromatin immunoprecipitation data confirmed that ACKR2 is directly regulated by HIF-1α at its promoter in B16-F10 melanoma cells. This study provides new key elements on how hypoxia can impair immune infiltration in the tumor microenvironment.

Peptides as modulators of FPPS enzyme: A multifaceted evaluation from the design to the mechanism of action

Bone diseases are medical conditions caused by the loss of bone homeostasis consecutive to increased osteoclast activity and diminished osteoblast activity. The mevalonate pathway (MVA) is crucial for maintaining this balance since it drives the post-translational prenylation of small guanosine triphosphatases (GTPases) proteins. Farnesyl pyrophosphate synthase (FPPS) plays a crucial role in the MVA pathway. Consequently, in the treatment of bone-related diseases, FPPS is the target of FDA-approved nitrogen-containing bisphosphonates (N-BPs), which have tropism mainly for bone tissue due to their poor penetration in soft tissues. The development of inhibitors targeting the FPPS enzyme has garnered significant interest in recent decades due to FPPS's role in the biosynthesis of cholesterol and other isoprenoids, which are implicated in cancer, bone diseases, and other conditions. In this study, we describe a multidisciplinary approach to designing novel FPPS inhibitors, combining computational modeling, biochemical assays, and biophysical techniques. A series of peptides and phosphopeptides were designed, synthesized, and evaluated for their ability to inhibit FPPS activity. Molecular docking was employed to predict the binding modes of these compounds to FPPS, while Surface Plasmon Resonance (SPR) and Nuclear Magnetic Resonance (NMR) spectroscopy experiments – based on Saturation Transfer Difference (STD) and an enzymatic NMR assay – were used to measure their binding affinities and kinetics. The biological activity of the most promising compounds was further assessed in cellular assays using murine colorectal cancer (CRC) cells. Additionally, genomics and metabolomics profiling allowed to unravel the possible mechanisms underlying the activity of the peptides, confirming their involvement in the modulation of the MVA pathway. Our findings demonstrate that the designed peptides and phosphopeptides exhibit significant inhibitory activity against FPPS and possess antiproliferative effects on CRC cells, suggesting their potential as therapeutic agents for cancer.

Assessment of the Anti-cancer Effects of Camel Milk Exosomes (CMEXOs) on Murine Colorectal Cancer Cell Line (CT-26).

Today, camel milk consumption in the Middle East is trendy because it is believed that it reduces the risk of cancer. Recently, studies have discovered that most of milk's beneficial effects are because of its nanoparticles, especially exosomes. The objective of the present research was to investigate the anti-cancer effects of camel milk exosomes (CMEXOs) in the murine colorectal cancer cell line (CT-26). Our findings verified the existence of exosomes measuring approximately 114.1±3.4 nm in diameter. Through MTT and migration assays, we established that CMEXOs exhibit dose-dependent anti-proliferative and anti-migration effects on the CT-26 cell line. Furthermore, our study showed that treatment with CMEXOs led to a reduction in TNF-α and IL-6 gene expression in CT-26 cells. While additional in vivo studies are required, our data demonstrate that CMEXOs have anti-proliferative and anti-migration effects on CT-26, possibly by influencing crucial genes within the inflammation pathway.

Limited impact of cancer-derived gangliosides on anti-tumor immunity in colorectal cancer.

Aberrant glycosylation is a key mechanism employed by cancer cells to evade immune surveillance, induce angiogenesis and metastasis, among other hallmarks of cancer. Sialic acids, distinctive terminal glycan structures located on glycoproteins or glycolipids, are prominently upregulated across various tumor types, including colorectal cancer (CRC). Sialylated glycans modulate anti-tumor immune responses through their interactions with Siglecs, a family of glycan-binding receptors with specificity for sialic acid-containing glycoconjugates, often resulting in immunosuppression. In this paper, we investigated the immunomodulatory function of ST3Gal5, a sialyltransferase that catalyzes the addition of α2-3 sialic acids to glycosphingolipids, since lower expression of ST3Gal5 is associated with better survival of CRC patients. We employed CRISPR/Cas9 to knock out the ST3Gal5 gene in two murine CRC cell lines MC38 and CT26. Glycomics analysis confirmed the removal of sialic acids on glycolipids, with no discernible impact on glycoprotein sialylation. Although knocking out ST3Gal5 in both cell lines did not affect in vivo tumor growth, we observed enhanced levels of regulatory T cells in CT26 tumors lacking ST3Gal5. Moreover, we demonstrate that the absence of ST3Gal5 affected size and blood vessel density only in MC38 tumors. In summary, we ascertain that sialylation of glycosphingolipids has a limited influence on the anti-tumor immune response in CRC, despite detecting alterations in the tumor microenvironment, possibly due to a shift in ganglioside abundance.

Abstract LB267: Disrupting cytoplasmic proton motive force induces ferroptotic cell death in colorectal cancer: A novel anti-cancer mechanism

Abstract Introduction: Chemotherapeutic resistance and tumor recurrence remain the leading causes of poor prognosis in colorectal cancer (CRC). Herein, we evaluated the anti-cancer effect of a novel repurposed drug HLN* in CRC. Methods: The changes in membrane potential were studied using DiSC(3) fluorescence by confocal microscopy. Cytotoxic activity of compound was studied using Sulphorhodamine-B (SRB) assay. Changes in mitochondrial membrane potential were studied using JC-1 dye. ROS accumulation was analyzed using DCFDA fluorescence using FACS analysis. Ferrorange assay was used to check the ferrous ion influx within the cell. Western blot was used to identify mode of cell death enacted. Results: Our results show that HLN treatment reduced the survival of human and murine CRC cells (CT26, HCT116, Colo 205 and MC38) with IC50 ranging 1-4 µM. HLN further inhibited proton motive force (PMF) by sequentially depolarizing and hyperpolarizing the cell membrane, as examined by cellular membrane potential using DiSC(3) dye by confocal microscopy. Disruption of the PMF leads to changes in various cellular signaling cascades including ROS production and mitochondrial membrane potential (MMP) changes. The MMP was significantly reduced by HLN treatment in CRC cells. Furthermore, we also observed an increase in ROS production by HLN. Pretreatment with N-acetyl cysteine (NAC), an antioxidant, blocked the effects of HLN. Interestingly, ferroptotic cell death markers GPX4, GPX1, SLC7A11/xCT, NRF2 and KEAP1 were significantly inhibited by HLN treatment in CRC cells as observed by western blotting. Ferroptotic induction was then confirmed using ferrorange assay wherein we observed a concentration dependent increase in ferrorange intensity indicating an increase in Fe+2. Overall, HLN dissipates ΔpH by modulating iron influx leading to ferroptotic cell death through ROS. Conclusion: Taken together, our results demonstrate the anti-cancer activity of a novel repurposed drug HLN and its unique mechanism of action. Our results provide a promise for developing this drug as a potential treatment option for CRC, through a novel anti-cancer mechanism. * Due to Intellectual property issued, the name of the drug is not provided Citation Format: Shreyas R. Gaikwad, Mohamed A. Eltokhy, Morgan Moore, Keerthi Kailath, Sanjay K. Srivastava. Disrupting cytoplasmic proton motive force induces ferroptotic cell death in colorectal cancer: A novel anti-cancer mechanism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB267.

Abstract 1688: Nuclear receptor coactivator SRC-1 promotes colorectal cancer immune escape by enhancing PD-L1 transcription and protein stability

Abstract Programmed death-ligand 1 (PD-L1), one of the immunosuppressive molecules, overexpresses in multiple cancers and is critical for their immune escape. We previously showed that the nuclear coactivator SRC-1 promoted colorectal cancer (CRC) progression by enhancing CRC cell viability; however, the role of SRC-1 in CRC immune escape is unclear. Here, we demonstrated that SRC-1 was positively correlated with PD-L1 in human CRC specimens. SRC-1 deficiency significantly inhibited PD-L1 expression in both human and murine CRC cells and retarded murine CRC growth in subcutaneous grafts by enhancing CRC immune escape via increasing tumor infiltration and antitumor activity of effector CD8+ T cells. Genetic ablation of SRC-1 in mice also decreased PD-L1 expression in AOM/DSS-induced murine CRC. These results suggest that tumor-derived SRC-1 promotes CRC immune escape by enhancing PD-L1 expression. Mechanistically, SRC-1 activated JAK-STAT signaling by inhibiting SOCS1 expression and coactivated STAT3 and IRF1 to enhance PD-L1 transcription as well as stabilized PD-L1 protein by inhibiting proteasome-dependent degradation mediated by speckle type POZ protein (SPOP). Pharmacological inhibition of SRC-1 improved the antitumor effect of PD-L1 antibody in both subcutaneous graft and AOM/DSS-induced murine CRC models. Taken together, our findings highlight a crucial role of SRC-1 in facilitating CRC immune escape and targeting SRC-1 in combination with PD-L1 antibody immunotherapy may be an attractive strategy for CRC treatment. Citation Format: Yilin Hong, Qiang Chen, Zinan Wang, Yong Zhang, Bei Li, Xu Kong, Pingli Mo, Nengming Xiao, Jianming Xu, Yunbin Ye, Chundong Yu. Nuclear receptor coactivator SRC-1 promotes colorectal cancer immune escape by enhancing PD-L1 transcription and protein stability [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 1688.

Abstract 5264: KRASG12C inhibition synergizes with checkpoint blockade in KRASG12C-mutated tumor model

Abstract Introduction: The KRASG12C mutation is found in 14% of non-small cell lung cancer (NSCLC) and 3% of colorectal cancer (CRC). Sotorasib (AMG510), which covalently binds to the mutated cysteine 12 of KRASG12C protein, became the first KRASG12C inhibitors approved by the FDA for KRASG12C-mutated NSCLC treatment. AMG510 not only increased apoptosis in cancer cells harboring KRASG12C mutation, but also re-modelled tumor microenvironment. Thus, to evaluate novel therapeutic strategies for treating KRASG12C-mutated tumors, we established a CT26-KRASG12C tumor model and explored the combination of AMG510 with anti-PD1 therapy. Methods: We knocked in KRASG12C mutation in murine CT26 colorectal cancer cells using CRISPR/Cas9 to generate CT26-KRASG12C cells. The mutation was confirmed by PCR sequencing. In vitro, CT26-KRASG12C cells were treated with AMG510 for 2h or 72h, and then p-ERK and cell viability were analyzed. In vivo, 3×105 CT26-KRASG12C cells were subcutaneously injected into BALB/c mice, and the tumor bearing mice were treated with AMG510 (30 mg/kg or 100 mg/kg, QD×21), anti-PD-1 (10 mg/kg, BIW×3) and combination of AMG510 and anti-PD-1. On day 5 after randomization, the composition of immune cells, including CD4+ T cells, CD8+ T cells, dendritic cells (DC), and natural killer (NK) cells in tumors were analyzed by flow cytometry. The mice with complete tumor regression were re-challenged with bilateral tumors of CT26-KRASG12C (3×105) and unrelated mouse breast tumor cells, 4T1 (3×105) to evaluate the effect on tumor growth. Results: Following confirmation of KRASG12C mutation, AMG510 treatment decreased p-ERK expression by ~50% and impaired the cell growth with IC50 value of 0.1802 μM in CT26-KRASG12C cells. In vivo, single treatment of AMG510 at 30 mg/kg or 100 mg/kg significantly inhibited tumor growth with TGI of 60% or 99% on day 15 after randomization, respectively (both p<0.001). Combined treatment of AMG510 (30 mg/kg or 100 mg/kg) and anti-PD-1 also led to significant tumor inhibition with TGI of 64% or 99% on the same day, respectively (both p<0.001), although PD-1 blockade didn’t show anti-tumor effect alone. Noticeably, combined treatment of AMG510 (100 mg/kg) and anti-PD-1 induced complete tumor regression in 3 of 10 mice, which remained cured 124 days later. Moreover, the combined treatment significantly improved survival compared to the AMG510 treatment alone. Notably, all 4T1 tumors grew, but none of the CT26-KRASG12C tumors were palpable in the cured mice after the re-challenge. In the control group, all tumors were well established. Additionally, combined treatment of AMG510 (100mg/kg) and anti-PD-1 markedly increased the infiltration of CD4+ T cells, DC, and NK cells in the tumors. Conclusion: The successfully established CT26-KRASG12C model is a useful tool for investigating therapeutic strategies to combine KRASG12C inhibitors with immunotherapy. Citation Format: Li Hua, Shuang Li, Chenpan Nie, Chenfei Zhang, Ludovic Bourre, Jingjing Wang. KRASG12C inhibition synergizes with checkpoint blockade in KRASG12C-mutated tumor model [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 5264.

Abstract 6690: Gut microbial metabolite butyrate facilitates antitumor efficacy of telomerase-specific oncolytic adenovirus via MHC-I and cGAS-STING pathway activation

Abstract Introduction: Gut microbiota has been reported to have a potential to modulate tumor sensitivity to chemo- or immuno-therapies although the underlying mechanism is still unclear. Oncolytic virotherapy is a promising antitumor treatment that selectively induces oncolytic cell death in tumor cells. We have previously developed OBP-702, a telomerase-specific oncolytic adenovirus armed with the p53 tumor suppressor gene, highlighting potent antitumor effects across different cancer types. To explore the potential of gut microbial metabolites, particularly butyrate, in augmenting the antitumor efficacy of oncolytic virotherapy. Materials and Methods: We assessed the synergistic antitumor effects of butyrate and OBP-702 in cytotoxic assay using two human (HCT116, SW48) and two murine (CT26, MC38) colorectal cancer cell lines in vitro, and the in vivo antitumor effects in subcutaneous tumor models using HCT116 and CT26. We explored underlying mechanisms of the synergistic effects, focusing on the influences of butylate on viral infectivity via Coxsackie-Adenovirus Receptor (CAR) and integrins, and antitumor immunity via tumor MHC-I expression and CD8-positive T cells. Results: Butyrate and OBP-702 showed potent synergistic effects in all four cell lines in vitro, and the combination suppressed tumor growth significantly in HCT116 and CT26 subcutaneous tumors compared to each monotherapy. These synergistic effects were produced by butyrate increasing the potential of OBP-702 by enhancing viral infection efficiency via upregulating expressions of CAR and integrins on tumor cells. Butyrate also increased MHC-I expression on tumor cells by activating the cGAS-STING pathway, leading to increased CXCL10 expression, which led to activation of antitumor immunity through recruitment of CD8-positive T cells in tumor tissues. The synergistic effects of butyrate and OBP-702 were proved in an orthotopic colorectal tumor model with liver metastases using CT26 cells expressing luciferase, in which this combination not only reduced tumor growth, but also improved survival by activating antitumor immunity via CD8-positive T cells. Conclusion: Butyrate and OBP-702 showed synergistic antitumor effects via activation of systemic antitumor immunity in addition to direct effects of butyrate on viral cytotoxic potential, which provides valuable insights into the development of innovative cancer treatment strategies. Citation Format: Masaki Sakamoto. Gut microbial metabolite butyrate facilitates antitumor efficacy of telomerase-specific oncolytic adenovirus via MHC-I and cGAS-STING pathway activation [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 6690.

Abstract 585: Regorafenib antitumor immune response is enhanced by a novel drug combination in CRC syngeneic model

Abstract Purpose: In the United States, colorectal cancer (CRC) is the second leading cause of cancer mortality. Metastatic CRC (mCRC) refractory to traditional chemotherapy is managed with regorafenib, a multiple-kinase inhibitor. However, patients show only a modest improvement in overall survival but experience high drug toxicity, adverse side effects, and poor tolerability. Thus, to reduce regorafenib-induced toxicity and to enhance antitumor activity, we combined it with a hybrid/dual JAK/HDAC small-molecule inhibitor (JAK/HDACi) to leverage the advantages of both JAK and HDAC inhibition in a single agent. With syngeneic mice, the efficacy and impact on immunomodulation of this drug combination was assessed. Methods: To assess effects of the agents, C57BL/6 immunocompetent mice were injected with MC38 murine CRC cells and treated with regorafenib (6mg/kg body wt) or JAK/HDACi (30mg/kg body wt), and their combination every third day for 21 days. Upon completion of the experiment, the tumors were harvested and processed for RNA and protein expression profiles. The effect of drug treatment on immune response was analyzed by nCounter Gene Expression assays (NanoString Technologies). Cytokines were measured in serum using the MesoScale Discovery mouse V-Plex Proinflammatory Panel kit. For pharmacokinetic studies, plasma samples were assayed from C57BL/6 treated with drugs after 1, 7, 21, and 48 hrs of treatment. Results: The combination treatment significantly reduced tumor growth (volume and weight),relative to the vehicle control or single treatments. Gene expression showed higher CD45 abundance score in the combination treatment. This is an exciting observation, as CD45 has phosphatase activity and dephosphorylates key targets of the drugs used in the study. Additionally, after treatment with the combination, there was higher expression of Gzmb and Gzme and lower expression of Cx3cr1, indicating enhanced immuno modulation relative to regorafenib alone. We confirmed these findings by immunoprofiling of tumors. Higher CD45 staining, noted in tumors of mice treated with the combination, corroborated the gene expression results. Pronounced CD8 T lymphocytes infiltration was observed in combination, compared to regorafenib alone. Reduction of proinflammatory cytokine, TNF-α was noted in the combination group. This is an interesting observation as CD45 negatively regulates TNF, and combination treated mice had highest number of CD45 positive cells. Pharmacokinetic studies showed that the bioavailability of regorafenib was elevated after combination treatment relative to single-agent treatment. Conclusions: Relative to the single agents, the combination of regorafenib with JAK/HDACi was more effective, with an elevated antitumor immune response and with sustained inhibition of tumor growth. A clinical trial to evaluate this combination for the treatment of mCRCs is warranted. Citation Format: Prachi Bajpai, Farrukh Afaq, Sameer Al Diffalha, Sumit Agarwal, Hyung Gyoon Kim, Dennis Otali, Sooryanarayana Varambally, Ashish Manne, Ravi Paluri, Moh’d Khushman, Upender Manne. Regorafenib antitumor immune response is enhanced by a novel drug combination in CRC syngeneic model [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 585.

Abstract 6011: Pharmacological inhibition of PMS2 increases tumor mutational burden, induces microsatellite instability and elicits immune mediated rejection in vivo

Abstract Tumors carrying defects in DNA mismatch repair (MMR-d) display high tumor mutational burden (TMB) and increased tumor neoantigen levels. MMR-d leads to accumulation of single nucleotide variants (SNVs) and insertions or deletions (indels) amongst repetitive DNA sequences generating microsatellite instability (MSI). Cancers that harbor >40% microsatellite variations are described as MSI-high (MSI-H). These tumors display unique clinical features including better prognosis, increased immune infiltration and remarkable response to immune checkpoint blockade (ICB) therapy. Colorectal cancer (CRC) patients with MMR-d often respond to therapies based on immune checkpoint blockade, whilst those with mismatch repair proficient (MMR-p) tumors do not. Therefore, identifying strategies to enhance the efficacy of immunotherapeutic treatments and transform this prevalent subgroup of CRCs from immunologically cold to hot remains an urgent and an unmet clinical need. We discovered NP1867 a first-in-class, potent, selective, covalent small molecule inhibitor of the DNA Mismatch Repair protein PMS2. We show by biochemical, biophysical, and protein-ligand X-ray crystallographic methods that NP1867 binds irreversibly to the ATP binding site of the N-terminal ATPase domain of PMS2. NP1867 displays potent binding to PMS2 in a NanoBRET cellular target engagement assay and inhibits MMR activity in mechanistic and functional cell-based assays of MMR-dependent DNA repair. Continuous treatment of murine CRC cell line CT26 (MMR-p) with NP1867 increases TMB, specifically enriches gained mutations with typical MMR-d related COSMIC mutational signatures, and elicits MSI-H status in a time-dependent manner, demonstrating for the first time that inhibition of PMS2 with a small molecule phenocopies the inactivation of MMR observed in patients. Remarkably, inoculation of immune-competent mice with CT26 cells pre-treated with NP1867 elicits tumor regressions in anti-PD1-treated animals, recapitulating the unique clinical features of MMR-d/MSI-H tumors. Conversely, no response is observed in immune-competent animals inoculated with control-treated cells. The extent of in vivo response correlates with the duration of in vitro NP1867 treatment and with the MSI-H status of treated CT26 cells. In conclusion, small molecule NP1867 functionally inhibits DNA MMR by targeting PMS2, enriches gained mutations with MMR-d COSMIC signatures, elicits MSI-H status, and enhances immune surveillance in preclinical models. These findings pave the way for the development of orally bioavailable compounds suitable for long-term dosing in animal models. Citation Format: Eleonora Piumatti, Alexia Hervieu, Philippe Riou, Julian Blagg, Adam Peall, Sam Weeks, Maria T. Rodríguez-Plata, Giuseppe Rospo, Sasi Arunachalam, Bettina Meier, Paige Tongue, Tessa McLaren, Kalpesh Parmar, Pradip Patel, David Clark, Gareth Langley, Charles Nichols, Benoît Rousseau, Paul Winship, Matthew Baker, Martin Drysdale, Giovanni Germano, Alberto Bardelli. Pharmacological inhibition of PMS2 increases tumor mutational burden, induces microsatellite instability and elicits immune mediated rejection in vivo [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 6011.

Interferon-γ in the tumor microenvironment promotes the expression of B7H4 in colorectal cancer cells, thereby inhibiting cytotoxic T cells

The bioactivity of interferon-γ (IFN-γ) in cancer cells in the tumor microenvironment (TME) is not well understood in the current immunotherapy era. We found that IFN-γ has an immunosuppressive effect on colorectal cancer (CRC) cells. The tumor volume in immunocompetent mice was significantly increased after subcutaneous implantation of murine CRC cells followed by IFN-γ stimulation, and RNA sequencing showed high expression of B7 homologous protein 4 (B7H4) in these tumors. B7H4 promotes CRC cell growth by inhibiting the release of granzyme B (GzmB) from CD8+ T cells and accelerating apoptosis in CD8+ T cells. Furthermore, interferon regulatory factor 1 (IRF1), which binds to the B7H4 promoter, is positively associated with IFN-γ stimulation-induced expression of B7H4. The clinical outcome of patients with CRC was negatively related to the high expression of B7H4 in cancer cells or low expression of CD8 in the microenvironment. Therefore, B7H4 is a biomarker of poor prognosis in CRC patients, and interference with the IFN-γ/IRF1/B7H4 axis might be a novel immunotherapeutic method to restore the cytotoxic killing of CRC cells.

MIIP downregulation drives colorectal cancer progression through inducing peri-cancerous adipose tissue browning

BackgroundThe enrichment of peri-cancerous adipose tissue is a distinctive feature of colorectal cancer (CRC), accelerating disease progression and worsening prognosis. The communication between tumor cells and adjacent adipocytes plays a crucial role in CRC advancement. However, the precise regulatory mechanisms are largely unknown. This study aims to explore the mechanism of migration and invasion inhibitory protein (MIIP) downregulation in the remodeling of tumor cell-adipocyte communication and its role in promoting CRC.ResultsMIIP expression was found to be decreased in CRC tissues and closely associated with adjacent adipocyte browning. In an in vitro co-culture model, adipocytes treated with MIIP-downregulated tumor supernatant exhibited aggravated browning and lipolysis. This finding was further confirmed in subcutaneously allografted mice co-injected with adipocytes and MIIP-downregulated murine CRC cells. Mechanistically, MIIP interacted with the critical lipid mobilization factor AZGP1 and regulated AZGP1’s glycosylation status by interfering with its association with STT3A. MIIP downregulation promoted N-glycosylation and over-secretion of AZGP1 in tumor cells. Subsequently, AZGP1 induced adipocyte browning and lipolysis through the cAMP-PKA pathway, releasing free fatty acids (FFAs) into the microenvironment. These FFAs served as the primary energy source, promoting CRC cell proliferation, invasion, and apoptosis resistance, accompanied by metabolic reprogramming. In a tumor-bearing mouse model, inhibition of β-adrenergic receptor or FFA uptake, combined with oxaliplatin, significantly improved therapeutic efficacy in CRC with abnormal MIIP expression.ConclusionsOur data demonstrate that MIIP plays a regulatory role in the communication between CRC and neighboring adipose tissue by regulating AZGP1 N-glycosylation and secretion. MIIP reduction leads to AZGP1 oversecretion, resulting in adipose browning-induced CRC rapid progression and poor prognosis. Inhibition of β-adrenergic receptor or FFA uptake, combined with oxaliplatin, may represent a promising therapeutic strategy for CRC with aberrant MIIP expression.

Antitumor effect of tubeimoside-I on murine colorectal cancers through PKM2-dependent pyroptosis and immunomodulation.

Induction of cancer cell death is an established treatment strategy, but chemotherapy drug-mediated apoptosis can be evaded by many tumors. Pyroptosis is a type of inflammatory programmed cell death (PCD) that is important for organism immunity. Tubeimoside-I (TBMS1) is a plant-derived component that exhibits antitumor activity. However, it is unclear how TBMS1 induces pyroptosis to inhibit colorectal cancer (CRC). In this study, we demonstrated that TBMS1 is able to induce pyroptosis in murine CRC cells and releases pro-inflammatory cytokines. Mechanistically, we found that TBMS1 inhibits CRC cell proliferation and migration and induces pyroptosis by activating caspase-3 and cleaving gasdermin E (GSDME) through the inhibition of PKM2. In the animal experiments, TBMS1 attenuated the weight of solid tumors, increased the proportion of CD8+ cytotoxic T cells, and reduced the content of M2-type macrophages in the spleen of tumor-bearing mice. Furthermore, TBMS1 inhibited M2-type polarization by blocking STAT6 pathway activation in RAW 264.7 cells. To sum up, our findings suggest that TBMS1 triggers pyroptosis in CRC by acting on the PKM2/caspase-3/GSDME signaling pathway. Additionally, it modulates the antitumor immune response in CRC murine models. This study provides a promising basis for the potential use of TBMS1 in treating CRC.

Towards Copper(I) Clusters for Photo-Induced Oxidation of Biological Thiols in Living Cells.

The cell redox balance can be disrupted by the oxidation of biological peptides, eventually leading to cell death, which provides opportunities to develop cytotoxic drugs. With the aim of developing compounds capable of specifically inducing fatal redox reactions upon light irradiation, we have developed a library of copper compounds. This metal is abundant and considered essential for human health, making it particularly attractive for the development of new anticancer drugs. Copper(I) clusters with thiol ligands (including 5 novel ones) have been synthesized and characterized. Structures were elucidated by X-ray diffraction and showed that the compounds are oligomeric clusters. The clusters display high photooxidation capacity towards cysteine - an essential amino acid - upon light irradiation in the visible range (450 nm), while remaining completely inactive in the dark. This photoredox activity against a biological thiol is very encouraging for the development of anticancer photoredox drugs.The in vitro assay on murine colorectal cancer cells (CT26) did not show any toxicity - whether in the dark or when exposed to 450 nm light, likely because of the poor solubility of the complexes in biological medium.

MiR-30e-5p overexpression promotes proliferation and migration of colorectal cancer cells by activating the CXCL12 axis via downregulating PTEN

To investigate the regulatory effects of miR-30e-5p on biological behaviors of colorectal cancer cells and the role of PTEN/CXCL12 axis in mediating these effects. Bioinformatic analysis was performed to explore the differential expression of miR-30e-5p between colorectal cancer tissues and normal tissues. RT-qPCR was used to detect the differential expression of miR-30e-5p in intestinal epithelial cells and colorectal cancer cells. Bioinformatics and dual luciferase assay were used to predict and validate the targeting relationship between miR-30e-5p and PTEN. Human and murine colorectal cancer cell lines were transfected with miR-30e-5p mimics, miR-30e-5p inhibitor, miR-30e-5p mimics+LV-PTEN, or miR-30e-5p inhibitor + si-PTEN. The changes in biological behaviors of the cells were detected using plate clone formation assay, CCK-8 assay, flow cytometry, scratch healing and Transwell assays. PTEN and CXCL12 expressions in the cancer cells were detected by Western blotting. The effects of miR-30e-5p inhibitor on colorectal carcinogenesis and development were observed in nude mice. Bioinformatic analysis showed that miR-30e-5p expression was significantly elevated in colorectal cancer tissues compared with the adjacent tissue (P < 0.01). Higher miR-30e-5p expression was detected in colorectal cancer cell lines than in intestinal epithelial cells (P < 0.01). Dual luciferase assay confirmed the targeting relationship between miR-30e-5p and PTEN (P < 0.05). Transfection with miR-30e-5p mimics significantly enhanced proliferation and metastasis and inhibited apoptosis of the colorectal cancer cells (P < 0.05), and co-transfection with LV-PTEN obviously reversed these changes (P < 0.05). MiR-30e-5p mimics significantly inhibited PTEN expression and enhanced CXCL12 expression in the cancer cells (P < 0.01), and miR-30e-5p inhibitor produced the opposite effect. Transfection with miR-30e-5p inhibitor caused cell cycle arrest in the cancer cells, which was reversed by co-transfection with si-PTEN (P < 0.05). In the in vivo experiments, the colorectal cancer cells transfected with miR-30e-5p inhibitor showed significantly lowered tumorigenesis. Overexpression of miR-30e-5p promotes the malignant behaviors of colorectal cancer cells by downregulating PTEN to activate the CXCL12 axis.

Electroacupuncture at “Zusanli(ST36)” alleviates 5-fluorouracil-induced renal injury in colorectal cancer-bearing mice by exerting effects on oxidative stress, inflammatory responses, and cell apoptosis: 电针“足三里”减轻大肠癌荷瘤小鼠5-FU化疗后肾损伤及其氧化应激、炎症反应和细胞凋亡的研究

ObjectiveTo observe the effect of electroacupuncture at “Zusanli (ST36)” on 5-fluorouracil (5-FU)-induced renal injury in colorectal cancer-bearing mice, and to further investigate its effects on oxidative stress, inflammatory responses, and cell apoptosis in mouse renal tissue. MethodsThirty-five male BALB/c mice were randomly divided into five groups of seven mice each, namely the control, CT26, 5-FU, sham point (SP), and ST36 (which received EA at the “ST36”) groups. With the exception of the control group, each group was subjected to establishment of a subcutaneous implantation tumor model using the murine CT26 colorectal cancer cell line. Once the models were successfully established, the 5-FU, SP, and ST36 groups received 5-FU injection solution intraperitoneally at a dose of 5 mg/mL once every three days over a 21-day period. Mice in the SP and ST36 groups additionally received an EA intervention after each intraperitoneal 5-FU injection. EA were performed on mice of the SP group at bilateral sham acupoints and on mice of the ST36 group at the bilateral “ST36” using the continuous wave mode at a frequency of 2 Hz for a duration of 5 min, intervention was administered once every two days for a duration of 21 days. Samples were collected from the mice at the end of the experiment. The pathological morphology of the renal tissue was observed using hematoxylin and eosin (HE) staining; the contents of creatine (Cre), blood urea nitrogen (BUN) and malondialdehyde (MDA), and superoxide dismutase (SOD) activity were measured using biochemical assays; the expression and nuclear translocation of nuclear factor kappa B p65 subunit (NF-κB p65) were measured by immunofluorescence; the expression levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in serum were measured by ELISA; cell apoptosis in renal tissue was detected using the TUNEL assay; and the expression levels of the anti-B-cell lymphoma/leukemia 2 (Bcl-2), Bcl-2-associated X protein (Bax), cleaved caspase-3, cleaved caspase-9, and cytochrome C (cyt c) in renal tissue were measured by Western blotting. ResultsCompared with the control group, mice of the CT26 group showed a significant increase in serum Cre content (P<0.01), but the difference in BUN content was not statistically significant (P>0.05). HE staining of renal tissue revealed clear structures with normal glomerular and renal tubular morphology. SOD activity was decreased (P<0.01); MDA content was increased, but the increase was not statistically significant (P>0.05). Differences in NF-κB p65 protein expression in the cytoplasm of renal tissue and serum levels of TNF-α, IL-6, and IL-1β were not statistically significant (all P>0.05). Results of immunofluorescent TUNEL staining indicated an absence of significant cell apoptosis. In the renal tissue, Bcl-2 protein expression was slightly increased (P<0.05), and the expression levels of Bax (P<0.01), cleaved caspase-3 (P>0.05), cleaved caspase-9 (P<0.01), and cyt c (P>0.05) were increased. Compared with the CT26 group, mice of the 5-FU group exhibited an increase in Cre (P<0.01) and BUN (P<0.05) content. HE staining of renal tissue revealed the presence of glomerular atrophy and dilated Bowman's capsular spaces. SOD activity was significantly decreased (P<0.01), while the increase of MDA content was not significant (P>0.05). The expression of NF-κB p65 in the nucleus and serum TNF-α, IL-6, and IL-1β levels showed significant increases (P<0.05). The cell apoptosis level was significantly increased. The protein expression of Bcl-2 (P<0.05), Bax (P<0.01), cleaved caspase-9 (P<0.01), and cyt c (P<0.05) was significantly increased. Compared with the 5-FU group, the ST36 group showed decreased serum Cre and BUN levels (both P<0.01). HE staining of renal tissue showed less renal tissue injury and less dilation of renal capsular cavities. SOD activity was significantly higher (P<0.01), while MDA content was lower (P<0.05). Nuclear expression of NF-κB p65 and serum TNF-α (P<0.05), IL-6 (P<0.05), and IL-1β (P<0.01) levels were lower. The cell apoptosis level was decreased relative to the 5-FU group. Bcl-2 protein expression was significantly increased (P<0.01), while the protein expression levels of Bax (P<0.01), cleaved caspase-3 (P<0.01), cleaved caspase-9 (P<0.01), and cyt c (P<0.05) also were reduced. ConclusionEA at “ST36” attenuated 5-FU-induced renal injury in colorectal cancer-bearing mice. The mechanism may be related to the regulation of renal oxidative stress, alleviation of inflammatory responses, and inhibition of cell apoptosis.

Harnessing NK cell-based immunotherapy to prevent the high-dose radiotherapy-inducing tumor survival recurrence

Natural killer cells play crucial roles in tumor immunosurveillance and serve as first responders to recognize abnormal cells. Radiotherapy is the mainstay of cancer treatment. However, the effect of high-dose radiotherapy on NK cells remains elusive. Here, we used tumor-bearing mice in the murine colorectal cancer cell line, MC38. The function of NK cells in tumor-draining lymph nodes and tumors was explored after the mice were treated using radiotherapy with 20 Gy and/or blocking antibody αTIGIT at the indicated time. High-dose radiotherapy shaped an immunosuppressive tumor microenvironment to support tumor growth, showing a decreased anti-tumor immunity phenotype in which effector T cells were reduced significantly. Furthermore, the production of functional cytokines and markers in NK cells, including CD107a, granzyme B, and IFN-γ, also remarkably decreased after radiotherapy, while the inhibitory receptor TIGIT was significantly upregulated by FACS analysis. The effect of radiotherapy was significantly elevated after treatment with the combination of radiotherapy and TIGIT inhibition. Moreover, this combination significantly decreased tumor recurrence. Our findings reported that local single high-dose radiotherapy shaped the immunosuppressive microenvironment and inhibited the function of NK cells. Our study revealed compelling evidence suggesting that the enhancement of NK cell function through TIGIT targeting is an effective strategy to mitigate immune suppression caused by high-dose radiotherapy, thereby promoting the inhibition of tumor recurrence.

Abstract 5136: Surgical stress promotes long-lasting protumorigenic changes in bone marrow derived progenitor cells

Abstract Introduction: Surgery is a crucial intervention for cancer patients. However, the perioperative period is characterized by an increased risk for accelerated growth of metastatic disease. Our recent work shows that the protumorigenic systemic inflammatory changes and the formation of neutrophil extracellular traps (NETs) persist months after surgery in both mice and humans, and parallel micrometastatic tumor growth and recurrence. Here we hypothesized that surgery may induce long-term sustained epigenetic and transcriptomic changes in bone marrow derived granulocytes-monocytes progenitor cells (GMPs) leading to functional reprogramming of mature neutrophils and persistent systemic release of these protumorigenic NET-forming neutrophils. Methods: Eight-week-old mice were subjected to non-lethal surgical stress (laparotomy) for 30 mins. Seven days after, mice were inoculated with 1x106 MC38 (murine colorectal cancer cells) subcutaneously. For bone marrow (BM) transplant model, a group of B6 congenic (CD45.1) mice were subjected to laparotomy. BM derived cells were harvested 7 days after the procedure and orthotopically transplanted into B6 CD45.2 irradiated (1000 rads) mice. After the establishment of hematopoiesis (6 weeks), MC38 cancer cells were implanted into the recipient mice. Results: Mice that underwent laparotomy had significantly increased tumor volume at 3 weeks compared to control mice, that only underwent anesthesia (Laparotomy vs control **p&amp;lt;0.01). While the intratumoral flowcytometry analysis showed no difference in the frequency of infiltrating immune cells, quantitative (q) PCR analysis revealed significant plasticity in the tumor infiltrating neutrophils (TANs) observed by an increase in the expression of genes (MCP1, Arg1) associated with pro-inflammatory (N2) type neutrophils compared to control. A persistent increased level of NETs was also observed within the tumors and circulation of mice several weeks after laparotomy. ATAC-seq and Bulk-RNA-seq analysis further revealed major epigenetic and transcriptomic changes in TANs, circulating neutrophils and GMPs. To substantiate long-lasting surgical effects, tumor burden was assessed in the BM recipient mice and showed to be significantly increased in mice that had received BM cells from laparotomy mice versus BM cells from sham group. Conclusion: Surgery promotes long-term rewiring of the bone marrow derived cells resulting in increased tumor growth. Understanding the underlying molecular mechanism may help with therapeutic interventions to prevent protumorigenic surgical effects and improve patient outcomes. Citation Format: Hamza O. Yazdani, Tony Haykal, Ruiqi Yang, Celine Tohme, David A. Geller, Samer Tohme. Surgical stress promotes long-lasting protumorigenic changes in bone marrow derived progenitor cells. [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 5136.

Abstract 3636: Liver endothelium secreted LRG1 promotes metastatic colorectal cancer growth through the HER3/RSK/EIF4B AXIS

Abstract Background: 25% of patients diagnosed with colorectal cancer (CRC) have liver metastasis at presentation, and ~80% of all metastatic CRC are developed in the liver. We previously reported that liver endothelial cells (ECs), a key component of the liver microenvironment, secrete LRG1 to promote CRC growth via activating human epidermal growth factor receptor (ERbB3, also known as HER3). However, we found that LRG1-induced HER3 activation is distinct from the canonical neuregulin 1 (NRG1)-induced HER3 pathway. The present study further validated LRG1 as a new HER3 ligand for promoting mCRC growth and elucidated the novel downstream signaling pathway induced by LRG1-HER3. Methods: We first measured the binding affinity between HER3 and LRG1 by Biolayer interferometry (BLI). We then used in vitro and in vivo xenograft approaches to determine the effect of LRG1 monoclonal antibody (15C4) on HER3 activation and CRC growth. To further determine the role of LRG1 in promoting CRC growth in the liver, we used murine CRC cells in a syngeneic orthotropic liver injection model to establish CRC allografts in the liver of LRG1−/− mice with systemic LRG1 knockout and wild-type siblings (LRG1+/+). We also performed unbiased phospho-MS analysis and subsequent validations to determine the downstream signaling pathway activated by LRG1-HER3. Results: We identified that LRG1 binds to HER3 with the affinity at ~100nM. The LRG1 antibody 15C4 completely attenuated LRG1-induced HER3 activation and in vitro and xenograft growth in vivo. Moreover, LRG1−/− mice with CRC allografts in the liver had 2 times longer overall survival than tumor-bearing LRG1+/+ mice. Lastly, unbiased -omics analysis identified eIF4-protein synthesis is significantly activated by LRG1. With target-specific inhibitors, we further determined that LRG1-HER3 activates the PI3K-PDK1-RSK1/3-eIF4 axis independent of AKT. Conclusions: We identified LRG1 as a novel HER3 ligand and demonstrated that the liver microenvironment-derived LRG1 plays a key oncogenic role in mCRC, by activating a novel RSK-eIF4 survival pathway. Our findings highlighted the potential of blocking LRG1-HER3 and involved downstream pathways for treating patients with mCRC. Citation Format: Moeez Ghani Rathore, Michelle Wright, Wei Huang, Derek Taylor, Yamu Li, Jordan Winter, Zhenghe Wang, John Greenwood, Stephen Moss, Rui Wang. Liver endothelium secreted LRG1 promotes metastatic colorectal cancer growth through the HER3/RSK/EIF4B AXIS. [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 3636.

Abstract 1317: Exercise training prevents exosome mediated pre-metastatic niche formation in the liver

Abstract Introduction: Primary tumor cells release exosomes facilitating pre-metastatic niche formation in distant organs, initiating the process of metastasis. As metastasis is the main prognostic factor for patients, it is essential to understand the pre-metastatic niches and develop therapies to target them. It has been shown that Kupffer cells play an crucial role in the formation of pre-metastatic niche in the liver. We have recently shown that exercise training (ExT) alters the phenotype of Kupffer cells and attenuates tumor metastasis after surgery. Here, we hypothesize that ExT can interfere with exosome mediated pre-metastatic niches, hence decreasing metastasis. Methods: Eight-week-old male mice were randomized into sedentary and ExT group. Mice were pre-educated with cancer exosomes for 4 weeks to induce pre-metastatic niche and intra-splenically injected with murine colorectal cancer (MC38) cells. Tumor metastasis and growth was followed by 3 weeks. Results: Compared to the sedentary group, there was a significant decrease in metastatic nodules and hepatic tumor replacement in the ExT mice liver. To further study the effects of ExT, livers from both groups were harvested 4 weeks after exosome pre-education. We observed decrease in the uptake of tumor exosome, immune cells infiltration and fibronectin deposition in the ExT livers, which demonstrates less pre-metastatic niche formation. Bulk RNA sequencing was performed on Kupffer cells isolated from both groups. Ingenuity pathway analysis shows that Triggering Receptor Expressed on Myeloid cells 1 (TREM1) signaling pathway was downregulated in EXT group, indicating less activation of Kupffer cells. Conclusions: These results indicate that exercise reduces pre-metastatic niche formation and tumor metastasis by affecting the interaction between cancer exosomes and Kupffer cells. In light of these findings, potential may exist to reduce exosome-induced liver pre-metastatic niches through the use of ExT as a nonpharmacologic therapy in patients with cancer. Citation Format: Ruiqi Yang, Tony Haykal, Celine Tohme, Ronghua Wang, Christof Kaltenmeier, David Geller, Hamza Yazdani, Samer Tohme. Exercise training prevents exosome mediated pre-metastatic niche formation in the liver [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 1317.