Trans-3, 5, 4′-trimethoxystilbene restrains non-small-cell lung carcinoma progression via suppressing M2 polarization through inhibition of m6A modified circPACRGL-mediated Hippo signaling

Background: Non-small-cell lung carcinoma (NSCLC) accounts for similar to 85% of all lung carcinomas. Trans-3,5,4 '-trimethoxystilbene (TMS) shows strong anti-tumor activity and induces tumor cell apoptosis. However, its function and mechanism in NSCLC still require investigation. Methods: PMA was used to treated THP-1 cells for macrophage differentiation. The abundance and m6A modification of circPACRGL were examined with qRT-PCR and MeRIP. Colony forming, transwell, wound healing, and Western blotting assays were applied to analyze proliferation, invasion, migration, and EMT. Macrophage polarization was determined through flow cytometry analysis of M1 and M2 markers. The interplay between circPACRGL, IGF2BP2 and YAP1 was validated by RNA pull-down and RIP assays. Mice received subcutaneous injection of NSCLC cells as a mouse model of subcutaneous tumor. Results: CircPACRGL was upregulated in NSCLC cells, but it was reduced by TMS treatment. CircPACRGL depletion blocked proliferation, migration, and invasion in H1299 and H1975 cells. TMS suppressed these malignant behaviors, but it was abolished by circPACRGL overexpression. In addition, NSCLC-derived exosomes delivered circPACRGL into THP-1 cells to promote its M2 polarization, but TMS inhibited these effects by downregulating exosomal circPACRGL. Mechanically, exosomal circPACRGL bound to IGF2BP2 to improve the stability of YAP1 mRNA and regulate Hippo signaling in polarized THP-1 cells. TMS inhibited NSCLC growth via suppressing Hippo signaling and M2 polarization in vivo. Conclusion: TMS restrains M2 polarization and NSCLC progression by reducing circPACRGL and inhibiting exosomal circPACRGL-mediated Hippo signaling. Thus, these findings provide a novel mechanism underlying NSCLC progression and potential therapeutic targets.