Transcriptomic analysis of control and macrophage-conditioned meduim treated MCF-7 breast cancer cells to investigate the mechanism of macrophage-induced TNT formation.

Tumor-associated macrophages (TAMs) secrete cytokines, chemokines, and growth factors in tumor microenvironment to support cancer progression. Previous studies have demonstrated role of macrophages in stimulating long range intercellular bridges referred as tunneling nanotubes (TNTs) in cancer cells. Intercellular communication between cancer cells via TNTs promote cancer growth, invasion, and therapy resistance. Given the important role of TNTs and macrophages in cancer, the mechanism of macrophage mediated TNT formation is elusive. In this study, it is shown that the macrophage-conditioned medium treated MCF-7 cells showed enrichment of NF?B and focal adhesion pathway as well as upregulation of genes involved in EMT, extracellular remodelling, and actin cytoskeleton reorganization. Interestingly, inhibition of PKC, Src, NF?B and p38 inhibited macrophage-induced TNT formation in MCF-7 cells. These results reveal novel role of PKC and Src in inducing TNT formation in cancer cells and suggest that inhibition of PKC and Src activity may likely contribute to reduced macrophage-breast cancer cell interaction and potential therapeutic strategy of cancer. Overall design: To investigate the mechanism of macrophage induced TNT formation in MCF-7 cells, we treated MCF-7 cells with macrophage conditioned medium derived from differentiated U937 cells. We then performed transcriptomic analysis using RNA seq data from control and macrophage conditined medium treated MCF-7 cells amd identified key genes that regulate TNT formation.