Abstract
The histone methyltransferase G9a is overexpressed in a variety of cancer types, including pancreatic adenocarcinoma, and promotes tumor invasiveness and metastasis. We recently reported the discovery of BRD4770, a small-molecule inhibitor of G9a that induces senescence in PANC-1 cells. We observed that the cytotoxic effects of BRD4770 were dependent on genetic background, with cell lines lacking functional p53 being relatively resistant to compound treatment. To understand the mechanism of genetic selectivity, we used two complementary screening approaches to identify enhancers of BRD4770. The natural product and putative BH3 mimetic gossypol enhanced the cytotoxicity of BRD4770 in a synergistic manner in p53-mutant PANC-1 cells but not in immortalized non-tumorigenic pancreatic cells. The combination of gossypol and BRD4770 increased LC3-II levels and the autophagosome number in PANC-1 cells, and the compound combination appears to act in a BNIP3 (B-cell lymphoma 2 19-kDa interacting protein)-dependent manner, suggesting that these compounds act together to induce autophagy-related cell death in pancreatic cancer cells.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Antineoplastic Agents / pharmacology*
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Autophagy
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Benzamides / pharmacology*
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Benzimidazoles / pharmacology*
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Cell Line, Tumor
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Drug Resistance, Neoplasm
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Drug Screening Assays, Antitumor
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Drug Synergism
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Gene Expression / drug effects
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Gossypol / pharmacology*
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Histocompatibility Antigens / genetics
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Histocompatibility Antigens / metabolism
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Histone-Lysine N-Methyltransferase / antagonists & inhibitors*
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Histone-Lysine N-Methyltransferase / genetics
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Histone-Lysine N-Methyltransferase / metabolism
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Humans
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Microtubule-Associated Proteins / metabolism
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Pancreatic Neoplasms
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Phagosomes / metabolism
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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Tumor Suppressor Protein p53 / genetics
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Tumor Suppressor Protein p53 / metabolism
Substances
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Antineoplastic Agents
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BNIP3 protein, human
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BRD4770
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Benzamides
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Benzimidazoles
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Histocompatibility Antigens
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MAP1LC3A protein, human
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Membrane Proteins
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Microtubule-Associated Proteins
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Proto-Oncogene Proteins
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TP53 protein, human
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Tumor Suppressor Protein p53
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EHMT2 protein, human
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Histone-Lysine N-Methyltransferase
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Gossypol