Deciphering genetic and nongenetic factors underlying tumour dormancy: insights from multiomics analysis of two syngeneic MRD models of melanoma and leukemia.

BACKGROUND: Tumour dormancy, a resistance mechanism employed by cancer cells, is a significant challenge in cancer treatment, contributing to minimal residual disease (MRD) and potential relapse. Despite its clinical importance, the mechanisms underlying tumour dormancy and MRD remain unclear. In this study, we employed two syngeneic murine models of myeloid leukemia and melanoma to investigate the genetic, epigenetic, transcriptomic and protein signatures associated with tumour dormancy. We used a multiomics approach to elucidate the molecular mechanisms driving MRD and identify potential therapeutic targets. RESULTS: We conducted an in-depth omics analysis encompassing whole-exome sequencing (WES), copy number variation (CNV) analysis, chromatin immunoprecipitation followed by sequencing (ChIP-seq), transcriptome and proteome investigations. WES analysis revealed a modest overlap of gene mutations between melanoma and leukemia dormancy models, with a significant number of mutated genes found exclusively in dormant cells. These exclusive genetic signatures suggest selective pressure during MRD, potentially conferring resistance to the microenvironment or therapies. CNV, histone marks and transcriptomic gene expression signatures combined with Gene Ontology (GO) enrichment analysis highlighted the potential functional roles of the mutated genes, providing insights into the pathways associated with MRD. In addition, we compared "murine MRD genes" profiles to the corresponding human disease through public datasets and highlighted common features according to disease progression. Proteomic analysis combined with multi-omics genetic investigations, revealed a dysregulated proteins signature in dormant cells with minimal genetic mechanism involvement. Pathway enrichment analysis revealed the metabolic, differentiation and cytoskeletal remodeling processes involved in MRD. Finally, we identified 11 common proteins differentially expressed in dormant cells from both pathologies. CONCLUSIONS: Our study underscores the complexity of tumour dormancy, implicating both genetic and nongenetic factors. By comparing genomic, transcriptomic, proteomic, and epigenomic datasets, our study provides a comprehensive understanding of the molecular landscape of minimal residual disease. These results provide a robust foundation for forthcoming investigations and offer potential avenues for the advancement of targeted MRD therapies in leukemia and melanoma patients, emphasizing the importance of considering both genetic and nongenetic factors in treatment strategies.

Tumor microenvironment dynamics in oral cancer: unveiling the role of inflammatory cytokines in a syngeneic mouse model.

The process of cervical lymph node metastasis is dependent on the phenotype of the tumor cells and their interaction with the host microenvironment and immune system; conventional research methods that focus exclusively on tumor cells are limited in their ability to elucidate the metastatic mechanism. In cancer tissues, a specialized environment called the tumor microenvironment (TME) is established around tumor cells, and inflammation in the TME has been reported to be closely associated with the development and progression of many types of cancer and with the response to anticancer therapy. In this study, to elucidate the mechanism of metastasis establishment, including the TME, in the cervical lymph node metastasis of oral cancer, we established a mouse-derived oral squamous cell carcinoma cervical lymph node highly metastatic cell line and generated a syngeneic orthotopic transplantation mouse model. In the established highly metastatic cells, epithelial-mesenchymal transition (EMT) induction was enhanced compared to that in parental cells. In the syngeneic mouse model, lymph node metastasis was observed more frequently in tumors of highly metastatic cells than in parental cells, and Cyclooxygenase-2 (COX-2) expression and lymphatic vessels in primary tumor tissues were increased, suggesting that this model is highly useful. Moreover, in the established highly metastatic cells, EMT induction was enhanced compared to that in the parent cell line, and CCL5 and IL-6 secreted during inflammation further enhanced EMT induction in cancer cells. This suggests the possibility of a synergistic effect between EMT induction and inflammation. This model, which allows for the use of two types of cells with different metastatic and tumor growth potentials, is very useful for oral cancer research involving the interaction between cancer cells and the TME in tumor tissues and for further searching for new therapeutic agents.

Generation of Murine Chimeric Antigen Receptor-Modified T Cells for In Vivo Studies in Syngeneic Tumor Models.

CAR-T cell therapy has emerged as a potent and effective tool in the immunotherapy of refractory cancers. However, challenges exist in their clinical application, necessitating extensive preclinical research to optimize their function. Various preclinical in vitro and in vivo models have been proposed for such purpose; among which immunocompetent mouse models serve as an invaluable tool in studying host immune interactions within a more realistic simulation of the tumor milieu. We hereby describe a standardized protocol for the generation of high-titer γ-retroviral vectors through transfection of the HEK293T packaging cell line. The virus-containing supernatant is further concentrated using an inhouse concentrator solution, titrated, and applied to mouse T cells purified via a convenient and rapid method by nylon-wool columns. Using the method presented here, we were able to achieve high titer γ-retrovirus and highly pure mouse T cells with desirable CAR transduction efficiency. The mouse CAR T cells produced through this protocol demonstrate favorable CAR expression and viability, thus making them suitable for further in vitro/in vivo assays. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Production of γ-retroviral vectors from retrovirus-backbone plasmids Basic Protocol 2: Concentration of γ-retrovirus-containing supernatants Basic Protocol 3: Titration of concentrated γ-retrovirus Basic Protocol 4: Isolation and activation of mouse T cells Basic Protocol 5: Transduction of activated mouse T cells, assessment of CAR expression, and expansion of CAR T cells for further in vitro/in vivo studies Support Protocol: Surface staining of cells for flow cytometric assessment of CAR expression.

OMIP-105: A 30-color full-spectrum flow cytometry panel to characterize the immune cell landscape in spleen and tumor within a syngeneic MC-38 murine colon carcinoma model.

This panel was designed to characterize the immune cell landscape in the mouse tumor microenvironment as well as mouse lymphoid tissues (e.g., spleen). As an example, using the MC-38 mouse syngeneic tumor model, we demonstrated that we could measure the frequency and characterize the functional status of CD4 T cells, CD8 T cells, regulatory T cells, NK cells, B cells, macrophages, granulocytes, monocytes, and dendritic cells. This panel is especially useful for understanding the immune landscape in "cold" preclinical tumor models with very low immune cell infiltration and for investigating how therapeutic treatments may modulate the immune landscape.

EL4 Murine-Lymphoma-Stromal-Cell Fusion Hybrids Observed With Multiple Distinct Morphologies in the Primary Tumor and Metastatic Organs of a Syngeneic Mouse Model.

BACKGROUND/AIM: We and others have previously shown that cell fusion plays an important role in cancer metastasis. Color coding of cancer and stromal cells with spectrally-distinct fluorescent proteins is a powerful tool, as pioneered by our laboratory to detect cell fusion. We have previously reported color-coded cell fusion between cancer cells and stromal cells in metastatic sites by using color-coded EL4 murine lymphoma cells and host mice expressing spectrally-distinct fluorescent proteins. Cell fusion occurred between cancer cells or, between cancer cells and normal cells, such as macrophages, fibroblasts, and mesenchymal stem cells. In the present study, the aim was to morphologically classify the fusion-hybrid cells observed in the primary tumor and multiple metastases EL4 formed from cells expressing red fluorescent protein (RFP) in transgenic mice expressing green fluorescent protein (GFP), in a syngeneic model. MATERIALS AND METHODS: RFP-expressing EL4 murine lymphoma cells were cultured in vitro. EL4-RFP cells were harvested and injected intraperitoneally into immunocompetent transgenic C57/BL6-GFP mice to establish a syngeneic model. Two weeks later, mice were sacrificed and each organ was harvested, cultured, and observed using confocal microscopy. RESULTS: EL4 intraperitoneal tumors (primary) and metastases in the lung, liver, blood, and bone marrow were formed. All tumors were harvested and cultured. In all specimens, RFP-EL4 cells, GFP-stromal cells, and fused yellow-fluorescent hybrid cells were observed. The fused hybrid cells showed various morphologies. Immune cell-like round-shaped yellow-fluorescent fused cells had a tendency to decrease with time in liver metastases and circulating blood. In contrast fibroblast-like spindle-shaped yellow-fluorescent fused cells increased in the intraperitoneal primary tumor, lung metastases, and bone marrow. CONCLUSION: Cell fusion between EL4-RFP cells and GFP stromal cells occurred in primary tumors and all metastatic sites. The morphology of the fused hybrid cells varied in the primary and metastatic sites. The present results suggest that fused cancer and stromal hybrid cells of varying morphology may play an important role in cancer progression.

In Vivo Mouse Models for Adult Brain Tumors: Exploring Tumorigenesis and Advancing Immunotherapy Development.

Brain tumors, particularly glioblastoma (GBM), are devastating and challenging to treat, with a low 5-year survival rate of only 6.6%. Mouse models are established to understand tumorigenesis and develop new therapeutic strategies. Large-scale genomic studies have facilitated the identification of genetic alterations driving human brain tumor development and progression. Genetically engineered mouse models (GEMMs) with clinically relevant genetic alterations are widely used to investigate tumor origin. Additionally, syngeneic implantation models, utilizing cell lines derived from GEMMs or other sources, are popular for their consistent and relatively short latency period, addressing various brain cancer research questions. In recent years, the success of immunotherapy in specific cancer types has led to a surge in cancer immunology-related research which specifically necessitates the utilization of immunocompetent mouse models. In this review, we provide a comprehensive summary of GEMMs and syngeneic mouse models for adult brain tumors, emphasizing key features such as model origin, genetic alteration background, oncogenic mechanisms, and immune-related characteristics. Our review serves as a valuable resource for the brain tumor research community, aiding in the selection of appropriate models to study cancer immunology.

Characterization of a Syngeneic Orthotopic Model of Cholangiocarcinoma by [18F]FDG-PET/MRI.

Cholangiocarcinoma (CCA) is a type of primary liver cancer originating from the biliary tract epithelium, characterized by limited treatment options for advanced cases and low survival rates. This study aimed to establish an orthotopic mouse model for CCA and monitor tumor growth using PET/MR imaging. Murine CCA cells were implanted into the liver lobe of male C57BL/6J mice. The imaging groups included contrast-enhanced (CE) MR, CE-MR with static [18F]FDG-PET, and dynamic [18F]FDG-PET. Tumor volume and FDG uptake were measured weekly over four weeks. Early tumor formation was visible in CE-MR images, with a gradual increase in volume over time. Dynamic FDG-PET revealed an increase in the metabolic glucose rate (MRGlu) over time. Blood analysis showed pathological changes in liver-related parameters. Lung metastases were observed in nearly all animals after four weeks. The study concludes that PET-MR imaging effectively monitors tumor progression in the CCA mouse model, providing insights into CCA development and potential treatment strategies.

Systemic inflammation enhances metastatic growth in a syngeneic neuroblastoma mouse model.

BACKGROUND: We previously showed that total tumor resection enhances metastatic growth in a syngeneic metastatic mouse model of neuroblastoma. In this study, we further investigated which surgical factors contributed most to metastatic growth. METHODS: Tumor cells derived from MYCN transgenic mice were subcutaneously injected into wild-type mice. Mice were randomly assigned to receive partial resection (PR group), subcutaneous implantation of a sponge (Sp group), or observation (Obs group). The lymph node metastasis volume and the frequency of lung metastasis were compared 14 days after assignment by measuring C-reactive protein (CRP) and interleukin-6 (IL-6) levels. RESULTS: The lymph node metastasis volume in the Sp group was larger than in the Obs group (148.4 [standard deviation {SD}: 209.5] vs. 10.2 [SD 12.8] mm3). The frequency of lung metastasis was greater in the Sp group than in the PR group (11.9 [SD 12.2] vs. 6.6 [SD 4.0] counts/slide). The CRP level in the Sp group was higher than in the PR group (2.3 [SD 0.5] vs. 1.5 [SD 0.4] µg/mL), and the IL-6 level in the Sp group was higher than in the PR or Obs groups (28.4 [SD 34.5] vs. 12.4 [SD 19.0] vs. 5.4 [SD 8.1] pg/mL). CONCLUSION: Metastatic growth may be enhanced by systemic inflammation.

Corrigendum: Late-stage MC38 tumours recapitulate features of human colorectal cancer - implications for appropriate timepoint selection in preclinical studies.

[This corrects the article DOI: 10.3389/fimmu.2023.1152035.].

Cancer Cell Line Inhibition by Osmotic Pump-administered Xylitol in a Syngeneic Mouse Model.

Background: This study aimed to evaluate the effects of continuous administration of xylitol (a commonly used dental prebiotic) via a subcutaneous osmotic minipump in a B16F10 syngeneic mouse model. Methods: The B16F10 syngeneic model consisted of 6-8-week-old C57BL/6 male mice subcutaneously injected with five × 105 B16F10 cells suspended in 100 µl PBS in the right flank. The mice were randomly assigned to two groups: Group 1 was the treatment group with 10% xylitol-loaded pumps (n=10), while Group 2 was the control group with saline-loaded pumps (n=10). Alzet minipumps were implanted subcutaneously in the left flank of B16F10-injected mice once more than 50% of all mice developed palpable tumors. After pump implantation surgery, the mice were monitored daily and weighed 2-3x/week. Tumor sizes were measured with calipers 2-3x/week, and all mice were euthanized when their tumors became too large (20 mm on any axis or 2,000 mm3). The excised tumors were weighed and cut in half, with one half sent for histology and the other for metabolomic analysis. Results: The xylitol-treated group survived substantially longer than the control group. The tumor size was reduced by approximately 35% by volume. Histological sections of xylitol treat mice suggested reduced infiltration and angiogenesis, which is consistent with previous studies. The metabolomic analysis demonstrates that xylitol reduces the tumor production of histamine, NADP+, ATP, and glutathione from the tumor, thereby improving the host immune response with ROS reactive oxygen species. Conclusions: The results of this study suggest that xylitol has potential as an adjunct to oncological treatment and is being further investigated in comparison to monoclonal antibody therapy (Opdualag).

"Next top" mouse models advancing CTCL research.

This review systematically describes the application of in vivo mouse models in studying cutaneous T-cell lymphoma (CTCL), a complex hematological neoplasm. It highlights the diverse research approaches essential for understanding CTCL's intricate pathogenesis and evaluating potential treatments. The review categorizes various mouse models, including xenograft, syngeneic transplantation, and genetically engineered mouse models (GEMMs), emphasizing their contributions to understanding tumor-host interactions, gene functions, and studies on drug efficacy in CTCL. It acknowledges the limitations of these models, particularly in fully replicating human immune responses and early stages of CTCL. The review also highlights novel developments focusing on the potential of skin-targeted GEMMs in studying natural skin lymphoma progression and interactions with the immune system from onset. In conclusion, a balanced understanding of these models' strengths and weaknesses are essential for accelerating the deciphering of CTCL pathogenesis and developing treatment methods. The GEMMs engineered to target specifically skin-homing CD4+ T cells can be the next top mouse models that pave the way for exploring the effects of CTCL-related genes.

CDK12 Loss Promotes Prostate Cancer Development While Exposing Vulnerabilities to Paralog-Based Synthetic Lethality.

Biallelic loss of cyclin-dependent kinase 12 (CDK12) defines a unique molecular subtype of metastatic castration-resistant prostate cancer (mCRPC). It remains unclear, however, whether CDK12 loss per se is sufficient to drive prostate cancer development-either alone, or in the context of other genetic alterations-and whether CDK12-mutant tumors exhibit sensitivity to specific pharmacotherapies. Here, we demonstrate that tissue-specific Cdk12 ablation is sufficient to induce preneoplastic lesions and robust T cell infiltration in the mouse prostate. Allograft-based CRISPR screening demonstrated that Cdk12 loss is positively associated with Trp53 inactivation but negatively associated with Pten inactivation-akin to what is observed in human mCRPC. Consistent with this, ablation of Cdk12 in prostate organoids with concurrent Trp53 loss promotes their proliferation and ability to form tumors in mice, while Cdk12 knockout in the Pten-null prostate cancer mouse model abrogates tumor growth. Bigenic Cdk12 and Trp53 loss allografts represent a new syngeneic model for the study of androgen receptor (AR)-positive, luminal prostate cancer. Notably, Cdk12/Trp53 loss prostate tumors are sensitive to immune checkpoint blockade. Cdk12-null organoids (either with or without Trp53 co-ablation) and patient-derived xenografts from tumors with CDK12 inactivation are highly sensitive to inhibition or degradation of its paralog kinase, CDK13. Together, these data identify CDK12 as a bona fide tumor suppressor gene with impact on tumor progression and lends support to paralog-based synthetic lethality as a promising strategy for treating CDK12-mutant mCRPC.

Immune checkpoint inhibitor monotherapy is sufficient to promote microenvironmental normalization via the type I interferon pathway in PD-L1-expressing head and neck cancer.

Immune checkpoint blockers (ICBs) targeting programmed cell death protein 1 (PD-1) have been proven to be an effective first-line therapy against programmed cell death 1 ligand 1 (PD-L1; also known as CD274 molecule)-expressing head and neck squamous cell carcinoma (HNSCC) in recent KEYNOTE-048 trial. However, associated changes in the tumor microenvironment (TME) and underlying mechanisms remain elusive. Oral tumors in C57/BL6 mice were induced by administering 7,12-dimethylbenzanthracene into the buccal mucosa. Single-cell suspension was isolated from tumor tissue; proliferating cells were injected subcutaneously into the left flank of mice to establish Ajou oral cancer (AOC) cell lines. Subsequently, a syngeneic PD-L1-expressing HNSCC model was developed by injecting AOC cells into the buccal or tongue area. The model recapitulated human HNSCC molecular features and showed reliable in vivo tumorigenicity with significant PD-L1 expression. ICB monotherapy induced global changes in the TME, including vascular normalization. Furthermore, the antitumor effect of ICB monotherapy was superior to those of other therapeutic agents, including cisplatin and inhibitors of vascular endothelial growth factor receptor 2 (VEGFR2). The ICB-induced antitumorigenicity and TME normalization were alleviated by blocking the type I interferon pathway. In summary, ICB monotherapy is sufficient to induce TME normalization in the syngeneic model; the type I interferon pathway is indispensable in realizing the effects of ICBs. Furthermore, these results explain the underlying mechanism of the efficacy of ICB monotherapy against PD-L1-expressing HNSCC in the KEYNOTE-048 trial.

Study on the Extrapolability of Current Tumorgenicity Test With Mice by Comparing the Syngeneic or Allogeneic Mouse Transplantation Model.

The extrapolability of the current tumorigenicity test performed by transplanting human cell product into immunodeficient (NOG) mice was investigated. For this purpose, the susceptibility to form teratomas of NOG mice was assessed by transplanting undifferentiated human-induced pluripotent stem cells (hiPSCs) as positive control cells via the liver, striatum, or tail vein and evaluating the TPD50 value (dose required to form teratomas in half of the transplanted mice). This was then compared to the TPD50 of syngeneic or allogeneic mouse models. The TPD50 of C57/BL/6(B6)-iPSC or 129/Ola(129)-embryonic stem cell (ESC) transplanted into the liver of syngeneic mice was 4.08 × 105 and 4.64 × 104 cells, respectively, while the TPD50 of hiPSC administered into the liver of NOG mice was 4.64 × 104 cells. The TPD50 of B6-miPSC-synergic, 129-mESC-synergic, or 129-cell/B6 allogeneic transplantation into the striatum was 5.09 × 102, 1.0 × 104, and 3.73 × 104 cells, respectively, while that of hiPSC/NOG mice was 1.0 × 103 cells. The TPD50 for B6-miPSC or 129-mESC syngeneic tail vein infusion was 3.16 × 106 or 5.62 × 106 cells, respectively, while no incidence was observed from 1 × 107 B6-miPSCs in 129 mice or hiPSCs in NOG mice infusion study. Although the number of data sets was limited, these data indicate that the teratoma formation from transplanted undifferentiated hiPSCs via the liver or striatum in NOG mice is comparable to that in syngeneic or allogeneic mouse transplantation model, suggesting that the result of the current tumorigenicity test in NOG mice would provide useful information to infer the incidence of teratoma from residual undifferentiated hPSCs in hPSC-derived products after transplantation.

Characterization of the tumor microenvironment in the mouse oral cancer (MOC1) model after orthotopic implantation in the buccal mucosa.

BACKGROUND: Preclinical models are invaluable for studies of head and neck cancer. There is growing interest in the use of orthotopic syngeneic models, wherein cell lines are injected into the oral cavity of immunocompetent mice. In this brief report, we describe injection of mouse oral cancer 1 (MOC1) cells into the buccal mucosa and illustrate the tumor growth pattern, lymph node response, and changes in the tumor immune microenvironment over time. METHODS: MOC1 cells were injected into the buccal mucosa of C57BL6 mice. Animals were sacrificed at 7, 14, 21, or 27 days. Tumors and lymph nodes were analyzed by flow cytometry. RESULTS: All mice developed tumors by day 7 and required euthanasia for tumor burden and/or weight loss by day 27. Lymph node mapping showed that these tumors reliably drain to a submandibular lymph node. The proportion of intratumoral CD8+ T cells decreased over time, while neutrophilic myeloid cells increased dramatically. Growth of orthotopic MOC2 and MOC22 also showed similar growth patterns versus published data in flank tumors. CONCLUSIONS: When used orthotopically in the buccal mucosa, the MOC1 model induces a robust lymph node response and distinct pattern of immune cell infiltration, with peak immune infiltration by day 14.

Orthotopic and metastatic tumour models in preclinical cancer research.

Mouse models of disease play a pivotal role at all stages of cancer drug development. Cell-line derived subcutaneous tumour models are predominant in early drug discovery, but there is growing recognition of the importance of the more complex orthotopic and metastatic tumour models for understanding both target biology in the correct tissue context, and the impact of the tumour microenvironment and the immune system in responses to treatment. The aim of this review is to highlight the value that orthotopic and metastatic models bring to the study of tumour biology and drug development while pointing out those models that are most likely to be encountered in the literature. Important developments in orthotopic models, such as the increasing use of early passage patient material (PDXs, organoids) and humanised mouse models are discussed, as these approaches have the potential to increase the predictive value of preclinical studies, and ultimately improve the success rate of anticancer drugs in clinical trials.

Allograft Model of Aortic Arch Segment Grafting to Abdominal Aorta Through End-to-Side Anastomosis in Mice.

The mouse aortic transplantation model is a valuable tool for investigating the mechanisms of atherosclerosis regression, but few laboratories can generate it due to the operation difficulty, especially for the style of end-to-side anastomosis, which facilitates syngeneic heterotopic transplanting a plaque-rich aortic arch into the abdominal aorta. Here we provide a modified protocol for generating this allograft model, which is capable of overcoming several critical surgical challenges such as separating a longer abdominal aorta segment, reducing bleeding and thrombosis, optimizing aortotomy, and improving end-to-side anastomosis to guarantee a potent graft. By transplanting plaque-rich aortic arches into the abdominal aorta of wildtype mice, a high operation success rate (over 90%) was noted with aortic clamping time under 60 min, the graft potency was satisfactory evidenced by examinations of micro-CT, ultrasound, and lower limb blood flow measurement, while a significant atherosclerosis regression was observed in the grafts at 1 week after transplantation.

MYC is sufficient to generate mid-life high-grade serous ovarian and uterine serous carcinomas in a p53-R270H mouse model.

Genetically engineered mouse models (GEMM) have fundamentally changed how ovarian cancer etiology, early detection, and treatment is understood. However, previous GEMMs of high-grade serous ovarian cancer (HGSOC) have had to utilize genetics rarely or never found in human HGSOC to yield ovarian cancer within the lifespan of a mouse. MYC, an oncogene, is amongst the most amplified genes in HGSOC, but it has not previously been utilized to drive HGSOC GEMMs. We coupled Myc and dominant negative mutant p53-R270H with a fallopian tube epithelium-specific promoter Ovgp1 to generate a new GEMM of HGSOC. Female mice developed lethal cancer at an average of 15.1 months. Histopathological examination of mice revealed HGSOC characteristics including nuclear p53 and nuclear MYC in clusters of cells within the fallopian tube epithelium and ovarian surface epithelium. Unexpectedly, nuclear p53 and MYC clustered cell expression was also identified in the uterine luminal epithelium, possibly from intraepithelial metastasis from the fallopian tube epithelium (FTE). Extracted tumor cells exhibited strong loss of heterozygosity at the p53 locus, leaving the mutant allele. Copy number alterations in these cancer cells were prevalent, disrupting a large fraction of genes. Transcriptome profiles most closely matched human HGSOC and serous endometrial cancer. Taken together, these results demonstrate the Myc and Trp53-R270H transgene was able to recapitulate many phenotypic hallmarks of HGSOC through the utilization of strictly human-mimetic genetic hallmarks of HGSOC. This new mouse model enables further exploration of ovarian cancer pathogenesis, particularly in the 50% of HGSOC which lack homology directed repair mutations. Histological and transcriptomic findings are consistent with the hypothesis that uterine serous cancer may originate from the fallopian tube epithelium.

Pre and Post-high-intensity Interval Training Delays Colon Tumor Onset in a Syngeneic Mouse Model.

BACKGROUND/AIM: High-intensity interval training (HIIT) can trigger transient anti-tumor cytotoxicity through the mobilization of natural killer cells (NK cells) and myokines. Yet, the effects of HIIT on tumor development and microenvironment are unclear. MATERIALS AND METHODS: Male C57/BL6 mice were administered either MC38 of syngeneic colon cancer cells or vehicle in a single subcutaneous injection. Before injection, the training group completed four weeks of the HIIT program (progressive swimming training, 3/week, 10-12 min, 4-6% of body weight for overload). Following injection, trained mice continued to exercise for two additional weeks. RESULTS: Pre and post-HIIT training was effective in preventing tumor onset (p=0.0065), maintaining body weight gain, and counteracting splenomegaly by 40% compared to the tumor group. However, HIIT had no impact on suppressing tumor growth, modifying final tumor volume, or significantly changing tumor proliferation (Ki-67), connective tissue content, or DNA double-strand damage detected by phospho-histone gamma-H2AX (γ-H2AX). CONCLUSION: Pre and post-HIIT program is feasible for mice carrying a subcutaneous syngeneic tumor and effective in delaying tumor burden; however, HIIT did not alter colon tumor endpoints.