How CD300e affects tumor-associated macrophages in colon cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide and remains difficult to treat due to its genetic heterogeneity and a complex tumor microenvironment. Recent studies have focused on the role of tumor-associated macrophages (TAMs) in cancer progression and how their behaviour can be altered to improve treatment outcomes. One molecule of interest is CD300e, a receptor found on myeloid cells. Although CD300e typically activates immune responses, recent studies suggest that its activation in monocytes reduces the expression of antigen presentation molecules, which are essential for antigen presentation to T cells, meaning that CD300e activation may limit T cell mediated responses rather than promote them under certain conditions. To investigate the role of CD300e in CRC, we used a subcutaneous mouse model in wild-type (WT) and CD300e knockout (KO) mice. Tumors were induced by injecting MC38 cells and tumor growth was monitored over 21 days. At the end of the study, tissue and blood samples were collected for further analysis. We found that macrophages from CD300e KO mice had a higher phagocytic activity compared to those in WT mice, suggesting that CD300e may influence macrophage activity within the tumor environment. However, both groups showed similar tumor weight and volume at the time of the sacrifice, which was confirmed by statistical tests. These findings support the previous conclusion that CD300e promotes immune suppression by altering macrophage behaviour in tumors. Therefore, blocking CD300e could help enhance anti-tumor immune responses and improve CRC treatment.