Heterocellular spheroids as a model of liver metastasis

Modeling the processes occurring at various stages of cancer tumor metastasis is the basis for developing effective antimetastatic drugs. One of the most promising targets for antimetastatic therapy are single tumor cells in a dormant state in the liver, lungs, bones and/or other organs of patients - micrometastases. At the time of diagnosis of a malignant neoplasm, almost all patients already have multiple microme-tastases. Under certain conditions, a single dormant tumor cell transitions into a stemlike cell, and the growth of a secondary tumor node - macrometastasis - begins. The aim of this work was to model the transition of breast cancer micrometastasis into macrometastasis in heterocellular spheroids consisting of human liver cells, fibroblasts, and M0 macrophages. To model dormant tumor cells using the fluorescence-activated sorting method, a population of CD44'differentiated cells of the genetically modified T47D cell line expressing the red fluorescent protein RFP (T47D_Red) was isolated. To obtain liver heterospheroids, human hepatoma cells of the HepG2 line, immortalized human fibroblasts of the BJ-5ta line, M0 macrophages obtained from monocytes of the peripheral blood of healthy donors, and CD44 cells of the human breast cancer line T47D_Red were mixed in a ratio of 15:1:1:1 in a DMEM/F12 medium supplemented with 10% fetal calf serum, L-glutamine, and an antibiotic-antimycotic (Fig. 1a-e). IL6 was added to the medium to induce dedifferentiation of cancer cells within the heterospheroid. This resulted in the proliferation of single breast cancer cells and the formation of secondary tumor foci in the heterospheroid structure (Fig. 1g-j) by the 5th day of cultivation. It is important to note that the cells in the heterospheroid retained their viability for 7 days of cultivation (Fig. 1f, k). Thus, a model for the formation of breast cancer metastasis in the liver has been proposed. The advantage of the model is the ability to take into account intercellular interactions due to the inclusion of several cell types, which increases the efficiency of in vitro testing of promising antimetastatic, including immunotherapeutic and gene therapeutic, drugs using the proposed model. The article contains 1 Figure, 11 References. The Authors declare no conflict of interest.

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