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Synergistic Effect of Combined Inhibition of the Checkpoint kinase 1 and G9a Methyltransferase Pathways in Pancreatic Cancer
Author(s) -
Urrutia Guillermo,
Salmonson Ann,
Lomberk Gwen
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.835.1
Subject(s) - pancreatic cancer , cancer research , cancer , population , cell cycle , epigenetics , cancer cell , cell cycle checkpoint , apoptosis , kinase , chromatin , biology , chemistry , microbiology and biotechnology , medicine , biochemistry , genetics , dna , environmental health , gene
Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer‐related deaths in the United States with a devastating overall five‐year survival rate of less than five percent. Consequently, there is an urgent need to further improve our understanding of molecular mechanisms underlying PDAC development to identify innovative therapeutic targets. Our laboratory is focused on utilizing epigenetic inhibitors in novel therapeutic approaches. Our experimental design involves harnessing the capacity of cell cycle inhibitors to arrest cells in G2/M while combining them with epigenetic inhibitors, which by altering chromatin structure can give rise to an aberrant mitotic checkpoint response leading to rapid death ( Mol Cancer Res ; 15(8): 984–97). In the present study, we have optimized and tested an experimental combinatorial therapy for pancreatic cancer using the CHK1 inhibitor LY2606368 and the G9a (Eukaryotic Histone Methyltransferase 2) inhibitor BRD4770. Using MTS assay, we show that the growth of pancreatic cancer cells grown in monolayer is reduced by both LY2606368 and BRD4770 individually, while their combination achieves a synergistic effect, as calculated using the Chou and Talalay method. In addition, this synergistic effect is also observed using pancreatic cancer cells grown as 3D spheroids. Moreover, the combination of LY2606368 with either of two additional G9a inhibitors, BIX01294 or UNC0631, reveals similar synergy, further supporting the specificity of this effect. FACS analysis of cells treated with the LY2606368 and BRD4770 combination shows an increased population in G2/M at 24 hours and an apoptotic pre‐G1 signal. The apoptotic response coincides with the activation of caspases 3 and 7. In vivo studies demonstrate that targeting these pathways reduces pancreatic tumor growth in a subcutaneous pancreatic cancer xenograft model. In summary, these data establish that targeting the epigenetic regulator G9a in the context of cell cycle inhibition holds promise as a novel combinatorial therapy for pancreatic cancer. Support or Funding Information NIH R01CA178627; Advancing a Healthier Wisconsin Endowment This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .