This study was designed to validate the anticancer effects of morusin in human non-small cell lung cancer (NSCLC) cells. Morusin suppressed the cell growth and colony formation in a concentration-dependent manner in H1299, H460 and H292 cells. These anticancer activities were related with apoptosis induction proved by the accumulation of chromatin condensation, PARP cleavage, increase of sub-G1 phage and annexin V-positive cell population. Interestingly, signal transducer and activator of transcription 3 (STAT3) was dephosphorylated by morusin. Morusin suppressed the transcriptional activity of STAT3 and down-regulated the expression of STAT3 target genes. In addition, morusin inhibited the phosphorylation of epithelial growth factor receptor (EGFR), an upstream regulator of STAT3. The docking study showed that morusin directly binds to the tyrosine kinase domain of EGFR. Furthermore, the anticancer effects of morusin were consistently observed in erlotinib-resistant H1975 cells expressing L858R and T790 M mutant EGFR, suggesting that morusin can be used for the advanced NSCLC with acquired resistance to EGFR TKI. Taken together, our results demonstrate that morusin induced apoptosis in human NSCLC cells regardless of EGFR mutation status through inhibition of EGFR/STAT3 activation.

Tumor-associated macrophages (TAMs) are closely related with poor prognosis of cancers. The current study investigated whether lupeol regulates TAMs by focusing on the recruitment and polarization of macrophages. We found that lupeol suppressed the recruitment of THP-1 macrophages (THP-1 cells differentiated into macrophages) towards H1299 lung carcinoma cells by inhibiting plasminogen activator inhibitor-1 (PAI-1) production from H1299 cells. The reduced migration of THP-1 macrophages by lupeol was recovered by adding recombinant human PAI-1 as a chemoattractant. Knockdown of PAI-1 or treatment of tiplaxtinin, a PAI-1 inhibitor, in H1299 cells abrogated the chemotaxis of macrophages. Furthermore, lupeol suppressed the interleukin (IL)-4- and IL-13-induced M2 macrophage polarization. The mRNA expression of M2 macrophage markers and the phosphorylation of signal transducer and activator of transcription 6 (STAT6) were commonly decreased by lupeol in RAW264.7 cells. In addition, lupeol-suppressed M2 macrophage polarization led to the reduced migration of Lewis lung carcinoma (LLC) cells. Taken together, our results suggest that lupeol attenuates PAI-1-mediated macrophage recruitment towards cancer cells and inhibits M2 macrophage polarization.