Cancer-associated Fibroblasts (CAFs) Regulate Lung Cancer Malignant Progression by Transferring SERPINE2 (PN1) Via Exosomes.

Background and aim: Cancer-associated fibroblasts (CAFs), one of the most abundant stromal cell types in tumor microenvironment (TME), have been a potential target for cancer treatment such as lung cancer. However, the underlying mechanism by which CAFs promote lung cancer progression remains elusive.

Methods: We obtained primary CAFs, normal fibroblasts (NFs) and their exosomes, constructed protease nexin-1 (PN1) stably silenced or over-expressed CAFs cells using lentivirus. Bioinformatics was used to obtain the expression of PN1 in lung cancer and normal tissues, the relationship with overall survival, and the enriched pathways. The MTT assays and Transwell assays were performed to detect the proliferation, migration, and invasion abilities of lung cancer cells after treatments. Western blotting, qRT-PCR, immunohistochemistry, and xenograft models were used to illustrate how CAFs functions in lung cancer progression via exosomes.

Results: CAFs-derived exosomes, in which PN1 was higher expressed compared with NFs-derived ones, promoted effectively the proliferation, migration, and invasion of lung cancer cells A549 and H1975. Meanwhile, the expression of PN1 expressed higher in lung cancer tissues compared with normal ones, and was negatively associated with the overall survival rate of lung cancer patients. More importantly, over-expressing or silencing PN1 in A549 and H1975 could also promote or inhibit cell proliferation, migration, and invasion correspondingly. Furthermore, treated with PN1 over-expressed CAFs-derived exosomes, the lung cancer cells proliferation, migration, and invasion varied positively, and accompanied by activation of Toll-like and NF-κB signaling pathways. However, this phenomenon can be reversed by AN-3485, an antagonist of Toll-like pathway. Finally, over-expressing PN1 leads to an accelerated tumor growth by increasing the expression of proliferation biomarker Ki67 and activation of NF-κB signaling pathway in vivo.

Conclusions: CAFs promoted lung cancer progression by transferring PN1 and activating Toll-like/NF-κB signaling pathway via exosomes.