M2 macrophages reduce the effect of gefitinib by activating AKT/mTOR in gefitinib-resistant cell lines HCC827/GR.

Background: The biological behavior of cells change after they develop drug resistance, and the degree of resistance will be affected by the tumor microenvironment. Here, we aimed to explore the changes in the biological behavior of tumors and to observe the differences in the release of cytokines and chemokines which can influence the tumor microenvironment. We also aimed to study how TKIs-resistant cell lines recruit macrophages to reduce the sensitivity of the cells following gefitinib administration. Methods: We generated and maintained gefitinib-resistant cell lines to study the differences between gefitinib-sensitive cell lines according to clone formation, cell growth curve analysis, whole-exome sequencing, and qPCR ARRAY technology. We used the WNT/beta-catenin inhibitor, WNT/beta-catenin activator and overexpression beta-catenin lentivirus to observe the changes in CCL2. M2 macrophages and gefitinib-resistant cell lines HCC827/GR were cocultured to detect the viability gefitinib for inducing cell death. Results: The proliferation and migratory activities were much more pronounced in HCC827/GR cells. CCL2 expression was also enhanced and regulated by beta-catenin in HCC827/GR. CCL2 promoted the chemotactic ability of M2 macrophages. M2 macrophages reduced the antitumor effect of gefitinib treatment by activating AKT/mTOR. Conclusions: Gefitinib-resistant cell lines have stronger proliferation and migration capabilities, and attract macrophages by releasing more CCL2 to reduce the sensitivity of cells to gefitinib.