5-Iodotubercidin inhibits Epithelial to Mesenchymal Transition by inhibiting IKK/NFκB-dependent gene expression

Abstract

Epithelial to mesenchymal transition (EMT) is a process of trans-differentiation important for development, inflammation and cancer. Transforming Growth Factor-{beta} (TGF{beta}) is a physiologically relevant inducer of EMT. We had recently characterized the adenosine analogue, adenosine kinase inhibitor 5-Iodotubercidin (5-ITu), as a compound which preferentially sensitizes MK2-deficient cells to TNF-induced, RIPK1-dependent cell death. Here we investigated the effect of 5-ITu on TGF{beta}-induced EMT. 5-ITu suppressed TGF{beta}-induced morphological changes and migration in A549 (lung cancer) and PANC1 (pancreatic cancer) cell lines. Consistent with these effects, there was significant suppression of EMT markers as indicated by qPCR, immunoblotting and immunofluorescence and confocal microscopy. Mechanistic investigations revealed that 5-ITu-mediated EMT suppression was independent of adenosine kinase inhibition and RIPK1 activation. 5-ITu suppressed NF{kappa}B activity in cells undergoing EMT and IKK inhibition phenocopied the effect of 5-ITu on EMT. Kinase assays revealed IKK{beta} as a potential direct target of 5-ITu. We identified a TGF{beta}-associated, NF{kappa}B-dependent gene signature consisting of 4 genes, which are differentially regulated upon 5-ITu treatment. Interestingly, this 4 gene signature could predict survival in lung and pancreatic cancer. The identification of this role for the multitarget kinase inhibitor 5-ITu in NF{kappa}B activity-dependent EMT, in addition to RIPK1-dependent necroptosis has potential implications in anticancer strategies.