Inactivation of the Euchromatic Histone-Lysine N -Methyltransferase 2 Pathway in Pancreatic Epithelial Cells Antagonizes Cancer Initiation and Pancreatitis-Associated Promotion by Altering Growth and Immune Gene Expression Networks

• Published in: Frontiers in cell and developmental biology 2021-06, Vol.9, p.681153
• Main Authors: Urrutia, Guillermo, de Assuncao, Thiago Milech, Mathison, Angela J, Salmonson, Ann, Kerketta, Romica, Zeighami, Atefeh, Stodola, Timothy J, Adsay, Volkan, Pehlivanoglu, Burcin, Dwinell, Michael B, Zimmermann, Michael T, Iovanna, Juan L, Urrutia, Raul, Lomberk, Gwen
• Format: Article
• Language: English
• Subjects: Cell and Developmental Biology; epigenomics; gene regulatory networks; histone methyltransferases; pancreatic carcinoma; tumor microenvironment
• ISSN: 2296-634X; 2296-634X
• DOI: 10.3389/fcell.2021.681153

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive, painful disease with a 5-year survival rate of only 9%. Recent evidence indicates that distinct epigenomic landscapes underlie PDAC progression, identifying the H3K9me pathway as important to its pathobiology. Here, we delineate the role of Euchromatic Histone-lysine -Methyltransferase 2 (EHMT2), the enzyme that generates H3K9me, as a downstream effector of oncogenic KRAS during PDAC initiation and pancreatitis-associated promotion. inactivation in pancreatic cells reduces H3K9me2 and antagonizes Kras -mediated acinar-to-ductal metaplasia (ADM) and Pancreatic Intraepithelial Neoplasia (PanIN) formation in both the and mouse models. acinar explants also show impaired EGFR-KRAS-MAPK pathway-mediated ADM upon deletion. Notably, Kras increases EHMT2 protein levels and EHMT2-EHMT1-WIZ complex formation. Transcriptome analysis reveals that inactivation upregulates a cell cycle inhibitory gene expression network that converges on the pathway. Congruently, pancreas tissue from animals with inactivation have increased P21 protein levels and enhanced senescence. Furthermore, loss of reduces inflammatory cell infiltration typically induced during Kras -mediated initiation. The inhibitory effect on Kras -induced growth is maintained in the pancreatitis-accelerated model, while simultaneously modifying immunoregulatory gene networks that also contribute to carcinogenesis. This study outlines the existence of a novel KRAS-EHMT2 pathway that is critical for mediating the growth-promoting and immunoregulatory effects of this oncogene , extending human observations to support a pathophysiological role for the H3K9me pathway in PDAC.