Abstract:
:Dysfunction of p53 and resistance to cancer drugs can arise through mutually exclusive overexpression of MDM2 or MDM4. Cisplatin-resistant cells, however, can demonstrate increased binding of both MDM2 and MDM4 to p53 but in absence of cellular overexpression. Whether MDM2 inhibitors alone can activate p53 in these resistant cells was investigated with the goal to establish the mechanism for potential synergy with cisplatin. Thus, growth inhibition by individual drugs and combinations was assessed by a colorimetric assay. Drug-treated parental A2780 and resistant tumor cells were also examined for protein expression using immunoblot and reverse phase protein array (RPPA) and then subjected to Ingenuity Pathway Analysis (IPA). Gene expression was assessed by real-time polymerase chain reaction, DNA damage by confocal microscopy, cell cycle by flow cytometry, and homologous recombination (HR) by a GFP reporter assay. Our results demonstrate that Nutlin-3 but not RITA (reactivation of p53 and induction of tumor cell apoptosis) effectively disrupted the p53-MDM2-MDM4 complex to activate p53, which increased robustly with cisplatin/Nutlin-3 combination and enhanced antitumor effects more than either agent alone. RPPA, IPA, and confocal microscopy provided evidence for an "apparent" increase in DNA damage resulting from HR inhibition by cisplatin/Nutlin-3. Molecularly, the specific HR protein Rad51 was severely downregulated by the combination via two mechanisms: p53-dependent transrepression and p53/MDM2-mediated proteasomal degradation. In conclusion, Nutlin-3 fully destabilizes the p53-MDM2-MDM4 complex and synergizes with cisplatin to intensify p53 function, which then downregulates Rad51 through a bimodal mechanism. As a result, HR is inhibited and antitumor activity enhanced in otherwise HR-proficient sensitive and resistant tumor cells. SIGNIFICANCE STATEMENT: Rad51 downregulation by the combination of cisplatin and Nutlin-3 inhibits homologous recombination (HR), which leads to persistence in DNA damage but not an increase. Thus, inhibition of HR enhances antitumor activity in otherwise HR-proficient sensitive and resistant tumor cells.
journal_name
Mol Pharmacoljournal_title
Molecular pharmacologyauthors
Xie X,He G,Siddik ZHdoi
10.1124/mol.119.117564subject
Has Abstractpub_date
2020-04-01 00:00:00pages
237-249issue
4eissn
0026-895Xissn
1521-0111pii
mol.119.117564journal_volume
97pub_type
杂志文章abstract::Reconstitution experiments with purified components reproduce the basic characteristics of receptor/G protein coupling, i.e., GTP-sensitive high affinity agonist binding and receptor-promoted GTP binding. However, the interaction of agonists with the A1 adenosine receptor in rat and bovine but not human brain membrane...
journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
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abstract::The role of mobilization of intracellular Ca2+ in the adrenergic-stimulated cAMP accumulation in rat pinealocytes was investigated with thapsigargin, an agent that inhibits endoplasmic reticulum Ca2+-ATPase. It was found that although thapsigargin alone had no effect on the basal cAMP accumulation, it potentiated the ...
journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
pub_type: 杂志文章
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更新日期:1998-01-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
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更新日期:2008-03-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:10.1124/mol.108.052464
更新日期:2009-03-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:10.1124/mol.111.076307
更新日期:2012-03-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:10.1124/mol.107.038596
更新日期:2008-02-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1993-05-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1986-11-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1998-06-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1982-07-01 00:00:00
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pub_type: 杂志文章
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1996-09-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1986-10-01 00:00:00
abstract::The glucagon-like peptide-1 receptor (GLP-1R) is a key physiological regulator of insulin secretion and a major therapeutic target for the treatment of type II diabetes. However, regulation of GLP-1R function is complex with multiple endogenous peptides that interact with the receptor, including full-length (1-37) and...
journal_title:Molecular pharmacology
pub_type: 杂志文章
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更新日期:2011-09-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
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更新日期:2004-05-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
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更新日期:2017-09-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1998-06-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章,收录出版
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更新日期:2011-02-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1992-01-01 00:00:00
abstract::We have cloned new 5-Hydroxytryptamine 4 (5-HT4) receptor splice variants from mouse (m5-HT4(e)R and m5-HT4(f)R), rat (r5-HT4(e)R), and human brain tissue (h5-HT4(e)R) which differ, as do the previously described 5-HT4 receptor variants, in the length and composition of their intracellular C termini after the common s...
journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1999-05-01 00:00:00