Exosomes derived from PM2.5‑treated lung cancer cells promote the growth of lung cancer via the Wnt3a/β‑catenin pathway

Fine particulate matter (PM2.5) is associated with an increased lung cancer risk. However, the effect of PM2.5 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 PM2.5. These exosomes activated β‑catenin signalling in A549 cells. These exosomes exhibited no effects on migration and invasion, but promoted proliferation of A549 cells via the Wnt3a/β‑catenin pathway in vitro. These exosomes promoted A549 tumour progression in a Wnt3a‑dependent fashion in vivo. These results demonstrated that PM2.5 has a direct effect on promoting lung tumour development. Inhibition of exosome production by tumour cells or blockade of the Wnt3a/β‑catenin pathway represents a promising strategy to impede PM2.5‑mediated lung tumour progression.