RESUMO
Early diagnoses and treatment methods are being constantly improved, but cancer metastasis remains a main cause of mortality in malignant tumor patients. Lung is thought to be the organ most prone to distal metastasis among malignant tumors due to its unique physiological and pathological character. Tumor lung metastasis is unpredictable and may result in irreversible damages. Presently, no exact mechanism or specific targeting therapies are found. Depending on the unique theory system-treatment based on symptom differentiation, traditional Chinese medicine has made significant progress on controlling tumor lung metastasis, but its application methods and mechanism still need further study and exploration. More appropriate and idealized animal models are required as a studying medium. Therefore, the establishment of animal models to simulate lung metastasis of cancer patients has become the key to the study of tumor lung metastasis. In order to produce a better platform for investigating the pathogenesis, underlying mechanism, early diagnosis and therapeutics for tumor lung metastasis, and to provide reference for the selection and establishment of mouse lung metastasis model, this article would introduce the implementation, application and estimation of several common methods (tail vein injection, mammary fat pad orthotopic injection, tibia injection, tissue orthotopic implantation, transgenic mice and so on). Meanwhile, the development of mouse lung metastasis model still needs expanding of thoughts, rational and flexible utilization of existing models, and interdisciplinary cooperation to establish preferable animal models and make results more reliable.
RESUMO
The diagnosis and treatment methods for cancer are being improved continually, but the mortality of cancer still remains high. At present, the academic circle has realized deficiency of existing treatment ideas, and the concept of cancer cells has been gradually changed from "extremely extinct" to "peaceful coexistence". The concept of "survival with tumors" is universally accepted in the cancer academia. The tumor microenvironment is the place where tumor cells survive and develop. Therefore, regulation of the tumor microenvironment has become an important new strategy for tumor treatment. Myeloid-derived suppressor cells (MDSCs) are a group of heterogeneous cells that have immunosuppressive properties on T cells in the tumor microenvironment and play an important role in tumor immune escape. Now, therapy with MDSCs in the tumor microenvironment as the treatment targets also provides new ideas for the tumor treatment. As MDSCs subpopulations are similar with neutrophils and monocytes, they can be divided into two major subtypes:granulocyte-like myeloid-derived suppressor cells (G-MDSCs) and monocyte-myeloid-derived suppressor cells(M-MDSCs). But how to differ these two subtypes from neutrophils and monocytes. What are the differences in the functional characteristics of different subtypes of MDSCs. How do they accumulate, differentiate, and exert immunosuppressive effects through different pathways. Traditional Chinese medicine(TCM) has always been good at modulating the body's microenvironment. More and more researches have shown that, the recruitment, amplification and activation of MDSCs can be effectively inhibited by TCM compound and its active ingredients, providing scientific basis for Chinese medicine targeting MDSCs in the tumor microenvironment. However, which specific pathways could regulate G-MDSCs or M-MDSCs is still in need of further studies. Most previous literature focus on the overall level of MDSCs, while the this paper would be based on the specific subpopulations of MDSCs to clarify the biological characteristics of these two subtypes of MDSCs, so as to achieve more precise targeted therapy in the tumor microenvironment.