| Background:Colorectal cancer is one of the most common malignant tumors in the world.According to the latest epidemiological studies,colorectal cancer is the third most common cancer in the world,and the global mortality rate ranks second among all cancers.Although research on the molecular mechanisms and treatments for the colorectal cancer have been greatly developed in recent years,tumor metastasis remains one of the main causes of death in cancer patients.Currently,the common clinical treatments for colorectal cancer include surgery,chemotherapy,radiotherapy,targeted therapy,and immunotherapy,among which chemotherapy remains the cornerstone of colorectal cancer treatment.Although chemotherapy can significantly improve the survival of cancer patients and bring longterm clinical benefits,more and more studies have reported the phenomenon and mechanism of chemotherapy promoting tumor metastasis.Among chemotherapy drugs for colorectal cancer,oxaliplatin has been widely used as a first-line drug,and its potential liver toxicity has also been widely reported.However,there are few.studies on the correlation between oxaliplatin and tumor metastasis.Objective:Due to the potential liver toxicity of oxaliplatin,it is unclear whether oxaliplatin can affect tumor progression by altering the liver microenvironment and its underlying mechanisms.Therefore,this study aimed to explore the effect of oxaliplatin on colorectal cancer liver metastasis and further explore its potential mechanism.Methods:In this study,the luciferase-expressing mouse colorectal cancer cell line CT26(CT26-Luc)was used to construct liver metastasis models in BALB/c mice and BALB/cnude mice through intrasplenic injection.And Imaging small animals in vivo system and HE staining were used to evaluate the impact of chemotherapy drugs on tumor liver metastasis.The activities of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)in the peripheral blood of mice were measured to detect the effect of oxaliplatin treatment on liver function.We used single-cell RNA sequencing technology to reveal the liver transcriptome and analyze the impact of oxaliplatin treatment on the liver microenvironment.We then explored the potential mechanism of oxaliplatinpromoting metastasis through single-cell data and verified it using in vivo and in vitro experiments.Flow cytometry and immunofluorescence staining methods were used to detect the number and proportion of different immune cells in tissues.CellTrace CFSE Cell Proliferation staining method was used to evaluate T cell proliferation ability,the LDH cytotoxicity method was used to detect the killing ability of T cells against tumor cells,and Annexin V-FITC/PI staining was used to determine the effect of oxaliplatin on T cell apoptosis.Meta-analysis evaluated the correlation between lymphopenia and different survival periods of patients.Immunofluorescence staining was used to detect the effect of clinical chemotherapy drugs on the composition of immune cells in the liver of patients with colorectal cancer liver metastasis.Results:Oxaliplatin treatment significantly enhances colorectal cancer liver metastasis.HE staining and detection of peripheral blood alanine aminotransferase and alanine aminotransferase activities showed that oxaliplatin did not cause significant liver injury.The results of liver single cell RNA sequencing showed that oxaliplatin treatment can significantly alter the liver immune microenvironment.The overall number of macrophages decreased significantly,while the proportion of M2 macrophages increased,and immune regulatory genes related to suppressing T cell activation upregulated in these M2 macrophages.Analysis of T cells showed a decreasing trend in the number of T cells in the oxaliplatin group.Transcriptome analysis showed that oxaliplatin caused T cells to present a low immune response state and significantly inhibited T cell proliferation,activation and immune effector functions.In vivo and in vitro experiments verified the effects of oxaliplatin treatment on T cell proliferation,apoptosis,killing function and activation ability.Oxaliplatin-induced liver metastasis was significantly inhibited when mice were treated with T cell supplementation.Meta-analysis showed that the occurrence of chemotherapy-related lymphopenia was significantly associated with shortened overall survival,progression-free survival,and distant metastasis-free survival.And compared with other survival,lymphopenia has a higher risk(HR value)of shortening distant metastasis-free survival.Using immunofluorescence detection of the liver immune microenvironment in patients with colorectal liver metastasis,we found that the total immune cells,macrophages,and T cells in the liver of patients who received oxaliplatincontaining chemotherapy before surgery were significantly reduced.The phenomenon is consistent with what we observed in animal models.Conclusion:Our study suggests that oxaliplatin can promote liver metastasis of colorectal cancer by inducing the liver immunosuppressive microenvironment,reducing the number of liver macrophages and T cells,inducing the emergence of immunosuppressive macrophages,and inhibiting T cell proliferation,activation,and immune response functions.This presents new consideration to the clinical application of oxaliplatin,aiming to balance its anti-cancer and pro-metastasis effects as much as possible to achieve optimal clinical benefits. |
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