Exosomes derived from -treated lung cancer cells promote the growth of lung cancer via the Wnt3a/-catenin pathway

Fine particulate matter (P[M.sub.2.5]) is associated with an increased lung cancer risk. However, the effect of P[M.sub.2.5] exposure on lung cancer cells is still largely unknown. The present study revealed that A549 lung cancer cells secreted exosomes containing high levels of Wnt3a after treatment with P[M.sub.2.5]. These exosomes activated [beta]-catenin signalling in A549 cells. These exosomes exhibited no effects on migration and invasion, but promoted proliferation of A549 cells via the Wnt3a/[beta]-catenin pathway in vitro. These exosomes promoted A549 tumour progression in a Wnt3a-dependent fashion in vivo. These results demonstrated that P[M.sub.2.5] has a direct effect on promoting lung tumour development. Inhibition of exosome production by tumour cells or blockade of the Wnt3a/[beta]-catenin pathway represents a promising strategy to impede P[M.sub.2.5]-mediated lung tumour progression.