Tectorigenin ablates the inflammation-induced epithelial–mesenchymal transition in a co-culture model of human lung carcinoma

Tumors not only manage to escape from the host immune system, but they effectively contrive to benefit from infiltrating immune cells by modifying their functions so as to create a pro-inflammatory microenvironment favorable for tumor progression and metastasis. In this study we investigated if tectorigenin could suppress lung cancer-induced pro-inflammatory response generated from monocytes. A549:THP1 co-culture model was set-up favoring release of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α). Effect of tectorigenin on A549 imparted invasive phenotype of A549:THP-1 co-culture was monitored by cytokine release from monocytes, and metastasis/epithelial–mesenchymal transitiom (EMT) in A549 cells. In a contact A549:THP1 co-culture model, THP-1 cells were activated by A549 cells favoring secretion of pro-inflammatory cytokines, TNF-α and IL-6. However, priming of A549 cells with tectorigenin for 24 h repressed A549 cell-induced secretion of TNF-α and IL-6 by THP-1 cells. Tectorigenin induced change in functional phenotype of A549 cells rendered THP-1 cells non-responsive for the secretion of IL-6 and TNF-α in a contact co-culture setup. Additionally, conditioned media from this non-responsive A549:THP-1 co-culture suppressed metastatic potential of A549 cells as confirmed by the wound healing and transwell migration assays. These finding were further corroborated by decrease in expression of Snail with a concomitant increase in E-cadherin, the two signature markers of EMT. These results clearly demonstrate the therapeutic potential of tectorigenin to prevent lung cancer elicited inflammatory and pro-metastatic response in monocytes and warrants further investigations to elucidate its mechanism of action.