Cisplatin resistant lung cancer cells promoted M2 polarization of tumor-associated macrophages via the Src/CD155/MIF functional pathway

Lung cancer often ranks one of the most prevalent malignancies in the world. One of the most challenging aspects of treating late-stage lung cancer patients is the development of drug resistance, from both conventional chemo- and targeted therapeutic agents. Tumor-associated microphages (TAMs) have been shown to promote the survival and distant metastasis of lung cancer cells.

This study investigated the TAMs - modulating potential of cisplatin-resistant non-small cell lung cancer (NSCLC) cell lines, A549R and H460R by using bioinformatics approach, immunoblotting, immunofluorescence staining, migration, invasion, colony, lung sphere formation and xenograft tumorigenecity assays.

In this study, we first demonstrated the elevated expression of oncogenic and stemenss markers such as Src, Notch1, macrophage inhibitory factor (MIF) and CD155 in trained cisplatin (CDDP)-resistant A549 and H460 cells (A549R and H460R cells). When co-cultured with TAMs, A549R and H460R cells promoted the M2-polarization in TAMs. In addition, A549R and H460R cells showed an increased self-renewal ability as they formed tumor spheres at higher frequency comparing to their parental counterparts. The increased MIF secretion by the A549R and H460R cells could be suppressed by a multiple kinase inhibitor, dasatinib, which resulted in the decreased of oncogenic network of Src, CD155 and MIF expression. Similarly, dasatinib treatment reduced the M2 polarization in TAMs and suppressed self-renewal ability of the A549R and H460R cells.

In summary, cisplatin resistant lung cancer cells not only showed an increased self-renewal ability but also promoted M2 polarization of TAMs via the secretion of MIF. These findings were linked to the increased Src-associated signaling as dasatinib treatment significantly reversed these phenomena. Thus, kinase inhibitors such as dasatinib may be of potential for treating cisplatin-resistant lung cancer by targeting both tumor and the tumor microenvironment.