Protumoral effect of macrophage through Axl activation on mucoepidermoid carcinoma

Objective This study aims to test the potential involvement of Axl signaling in the protumoral effect of tumor‐associated macrophages ( TAM s) in mucoepidermoid carcinoma ( MEC ). Materials and Methods We carried out co‐cultured experiments by incubation of MEC cells ( UT ‐ MUC ‐1) and macrophages ( THP ‐1) and examined Axl activation status. The expression of MMP s and behavior change were examined in UT ‐ MUC ‐1 cells. The effect of Axl signaling on co‐cultured cancer cells was further investigated by knockdown Axl expression and suppression by Axl‐specific inhibitor R428. Results Activation of Axl signaling and increased expression and activity of MMP ‐2 and MMP ‐9 along with increased invasion/migration ability in MEC cells were observed when co‐cultured with TAM s. Upon knockdown of Axl in MEC or addition of R428 in the co‐cultured system, these co‐cultured effects were diminished. Conclusion TAM s play a protumoral role in MEC via activation of the Axl signaling pathway, up‐regulating MMP s expression, and increasing invasion/migration ability.