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Gemcitabine Exposure Induces Epigenomic Remodeling in Pancreatic Cancer Cells during Resistance Development
Author(s) -
Urrutia Guillermo,
Dusetti Nelson,
Iovanna Juan,
Urrutia Raul,
Lomberk Gwen
Publication year - 2020
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.2020.34.s1.05341
Subject(s) - epigenomics , gemcitabine , cancer research , pancreatic cancer , medicine , cancer , chromatin remodeling , epigenetics , oncology , biology , bioinformatics , dna methylation , gene , gene expression , genetics
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. Chemotherapy is a mainstay for PDAC treatment, with Gemcitabine (Gem) as a part of a first‐line regimen. Although Gem has shown clinical benefit, it possesses limited control over cancer progression, due to the major obstacle of chemoresistance. Consequently, there is an urgent need to further improve our understanding of molecular mechanisms underlying resistance development to identify innovative therapeutic targets. Our laboratory is focused on the use of epigenomic drugs as novel therapeutic approaches. Our experimental design involves developing chemoresistance in patient derived PDAC cells to identify epigenomic alterations and gene expression changes that can participate in the initiation and establishment of resistance to chemotherapeutic agents. Identifying such modifications can provide valid druggable targets to enhance the effect or reverse resistance to anti‐cancer drugs. In the present study, we induced resistance to Gem on a naïve patient‐derived PDAC cell line and evaluated epigenomic landscape remodeling through changes of histone post‐translational modifications. In addition, we characterized phenotypic changes in response to Gem exposure. Using the Incucyte® imaging system, we determined that exposure to increasing concentrations of Gem induced resistance on naïve patient‐derived PDAC cells. Gem resistant cells showed a reduced basal proliferation rate and apoptotic response compared to parental cells, as measured by activation of caspases 3 and 7. Additionally, cells developed morphological changes towards an epithelial state, coincident with the increase of Keratin 17/19 and E‐Cadherin. Moreover, treated cells demonstrated reduced sensitivity to the well‐known DNA damaging agents cisplatin and 5‐Fluorouracil. Evaluation of histone post‐translational modifications on these cells revealed reduction in the global amount of repressive marks (H3K9Me1, 2 and 3; H3K27Me2 and 3), as well as an increase of the activating histone mark H3K27Ac, associated with super enhancers. Furthermore, immunofluorescence‐based microscopy showed re‐distribution of the H3K9Me1 and H3K27Me3 repressive marks from the nuclear periphery to the whole nucleus, suggesting epigenomic remodeling of pancreatic cancer cells in response to the development of Gem resistance. In summary, these data demonstrate that Gem treatment induces chromatin remodeling and that targeting key epigenomic pathways may hold promise for novel strategies toward re‐sensitizing or preventing resistance of pancreatic cancer to chemotherapeutic agents.