PTX3 is a component of the humoral arm of innate immunity and an extrinsic oncosuppressor gene taming tumor-promoting inflammation. Here, we show that two enhancers differently regulate PTX3 expression: enhancer 1, located 230 kb upstream of PTX3 promoter, mediated the action of inflammatory transcription factors; and enhancer 2, encompassing PTX3 second exon, was implicated in pre-initiation complex assembly. Polycomb repressive complex 2 silenced these regulatory elements and the promoter in basal condition. Enhancer 1 was epigenetically inactivated in early colorectal cancer (CRC) stages, while the promoter and enhancer 2 showed increasingly DNA methylation during CRC progression from adenomas to stage II and III CRC. Inhibition of DNA methylation rescued PTX3 expression in CRC. Finally, enhancer 1 acquired the binding of STAT3 in stage I CRC, and inhibition of STAT3 phosphorylation restored PTX3 activity and decreased enhancer 1 methylation. Thus, the expression of PTX3 is under the control of two enhancers, which emerge as important fine regulators of PTX3 expression in inflammation and cancer.
Epigenetic regulation of the extrinsic oncosuppressor PTX3 gene in inflammation and cancer / Rubino, M; Kunderfranco, P; Basso, G; Greco, CM; Pasqualini, F; Serio, S; Roncalli, M; Laghi, L; Mantovani, A; Papait, R; Garlanda, ; C,. - In: ONCOIMMUNOLOGY. - ISSN 2162-402X. - 6:7(2017). [doi: 10.1080/2162402X.2017]
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