Histone methyltransferase KMT2D inhibits ENKTL carcinogenesis by epigenetically activating SGK1 and SOCS1

Background Epigenetic alteration plays an essential role in the occurrence and development of extranodal natural killer/T cell lymphoma (ENKTL). Histone methyltransferase (HMT) KMT2D is an epigenetic regulator that plays different roles in different tumors, but its role and mechanism in ENKTL are still unclear. Methods We performed immunohistochemical staining of 112 ENKTL formalin-fixed paraffin-embedded (FFPE) samples. Then, we constructed KMT2D knockdown cell lines and conducted research on cell biological behavior. Finally, to further investigate KMT2D -mediated downstream genes, ChIP-seq and ChIP -qPCR was performed. Results The low expression of KMT2D was related to a decreased abundance in histone H3 lysine 4 mono- and trimethylation (H3K4me1/3). In KMT2D knockdown YT and NK-YS cells, cell proliferation was faster ( P < 0.05 ), apoptosis was decreased ( P < 0.05 ), the abundance of S phase cells was increased ( P < 0.05 ), and the level of H3K4me1 was decreased. Notably, ChIP-seq revealed two crucial genes and pathways downregulated by KMT2D . Conclusions KMT2D is a tumor suppressor gene that mediates H3K4me1 and influences ENKTL proliferation and apoptosis by regulating the cell cycle. Moreover, in ENKTL, serum- and glucocorticoid-inducible kinase-1 ( SGK1 ) and suppressor of cytokine signaling-1 ( SOCS1 ) are downstream genes of KMT2D .