Heme-TAMs prevent cancer cell apoptosis and drive growth, invasiveness, and metastasis

To study the impact of heme-TAMs on the growth, phenotype, and function of cancer cells, we cultured GFP-MC38 cells either alone or mixed with heme-treated macrophages in microwell plates, enabling us to collect large numbers of uniform spheroids for scRNA-seq. We observed that after four days, the size of GFP-MC38 spheroids regressed, and the tumor cells underwent apoptosis and decayed metabolically. In contrast, the presence of heme-TAMs within spheroids prevented apoptosis, supporting the extended growth of metabolically viable spheroids beyond 10 days of culture. Spheroids of MC38-GFP and MC38-GFP mixed with BMDMs that were stimulated with heme were grown in microwell plates for 4, 8, and 10 days. 9000 spheroids per condition were pooled and digested into single cells. Single-cell suspensions were directly used for GEM generation.