Analysis Of Tumorigenic And Immunological Characteristics Of Mouse Breast Stromal Tumor And Epithelial Tumor

Background:Tumor Microenvironment(TME)is an important place for tumor cells to escape immune surveillance and develop drug resistance.It is also the key to the colonization of circulating tumor cells and the generation of metastases.Intra-tumor heterogeneity(ITH)describes the different morphological,genetic,and phenotypic characteristics of tumor cells.This property is manifested in different types of tumor cells and in the same tumor.in the cell.Studies have shown that ITH is an important factor leading to tumor metastasis and drug resistance.However,current research on ITH and immune microenvironment between the anatomic margins and interiors of tumor masses is relatively inadequate.Objective:In this study,a highly metastatic 4T1 tumor mouse model was used to obtain tumor cell lines by cultivating the anatomical margins and internal cells of the tumor mass in the primary cells,and initially exploring the intratumoral heterogeneity and immune microscopy of tumor cells at different anatomical locations The environment provides relevant reference and support for breast cancer tumor metastasis and drug resistance research.Methods:(1)Using the mouse 4T1 breast cancer model,HE staining microscopic observation and other methods to explore the internal structure of mouse breast cancer tumors.PCR method was used to detect the expression difference of stromal cell tumor and epithelial cell tumor inflammatory factor and its receptor.Flow cytometry was used to detect the difference in the proportion of lymphocytes and myeloid-derived immune cells in stromal cell tumors and epithelial cell tumors.(2)To construct an epithelial cell tumor,stromal tumor tail vein injection/orthotopic transplantation model.The technique of paraffin-embedded section staining and other techniques were used to explore the metastasis of spleen,lung and tumor tissues and organs of the model mice.(3)Flow cytometry was used to detect the change trend of CD8~+T and G-MDSCs in the spleen,lung,liver,bone,peripheral blood and tumors of mice transplanted with stromal tumor tail vein injection.Results:(1)The anatomical margins and internal cell phenotypes of the 4T1 breast cancer tumor mass in mice were different,and they were named stromal tumor and epithelial tumor,respectively.There were significant differences in the expression of inflammatory factors and their receptor genes.The type of cells in the immune microenvironment of stromal tumors was complex,and the proportion of T cells was higher than that of epithelial tumor;the proportion of cells of myeloid origin(TAMs,TIDCs,MDSCs,etc.)in the immune microenvironment of epithelial tumor was higher than that of stromal tumor.(2)The tumorigenicity of stromal tumor cells was stronger than that of epithelial tumor and weaker than that of 4T1 cells;the metastatic ability was stronger than that of epithelial tumor and 4T1cells.(3)Compared with the saline control group and the epithelial tumor tail vein transplantation model,in the stromal tumor tail vein injection transplantation model,the overall trend of the proportion of CD8+T cells in the mouse spleen,lung,liver,bone,peripheral blood and tumor was negatively correlated with the increase in tumor volume and the degree of metastasis;the overall trend of G-MDSCs cell ratio was positively correlated with the increase in tumor volume and the degree of metastasis,and there was no significant difference with the 4T1 positive control group.Conclusion:Significant differences were found in the anatomical marginal location and internal tumors of mouse breast tumor masses in terms of cell morphology,gene expression,immune cell lineage,tumorigenicity,and metastasis,suggesting that intratumoral heterogeneity exists in tumors at different anatomic locations.