It has been illustrated that exosomes are critical factors in mediating the communication between tumour cells and stromal cells, and exosomes play an important role in promoting tumour growth, angiogenesis, immune escape and metastasis.įor example, pancreatic cancer‐derived exosomes contain high amount of macrophage migration inhibitory factor (MIF), which recruits macrophages to induce the formation of PMN in the liver and promote liver metastasis.Įxcept proteins, a large amount of exosomal miRNAs also play key roles in regulating tumour progression. Therefore, exploring the molecular mechanisms of lung tumour‐derived exosomes mediate the PMN formation is crucial for developing targeted treatment of lung cancer metastasis in the future.Įxosomes are lipid bilayer‐encapsulated microparticles (30‐100 nm) released by various types of cells, which contain various proteins, lipids, DNA and miRNAs. Tumour‐derived exosomes, which potentially travel from primary tumour site to a new metastatic site, act as a potential mediator for establishing PMN,īut the underlying mechanisms are not fully understood. Recent evidence suggests that prior to metastasis, tumour cells can induce pre‐metastatic niche (PMN) formation by altering the environment of distant tissues, which provides a suitable condition for tumour cells colonization, a key step of tumour metastasis. However, in several cases, the primary lung cancer has already metastasized prior to initial diagnosis. And the common metastatic sites of lung cancer are the lung, brain, liver, bone and adrenal gland.Īlthough there is the possibility of multiple primary lung cancer (MPLC), patients with more than one tumour lesions are generally considered as metastasis.Įarly treatment is important to reduce lung cancer‐associated metastasis and death. More than 70% of lung cancer patients' death is caused by metastasis. Lung cancer is one of the most common malignant tumours with the highest morbidity and mortality rate.