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Identification of a Potent Inhibitor of CREB-Mediated Gene Transcription with Efficacious in Vivo Anticancer Activity.

Xie F, Li BX, Kassenbrock A, Xue C, Wang X, Qian DZ, Sears RC, Xiao X - J. Med. Chem. (2015)

Bottom Line: In a continuing effort to discover more potent CREB inhibitors, a series of structural congeners of 3a was designed and synthesized.Biological evaluations of these compounds uncovered compound 3i (666-15) as a potent and selective inhibitor of CREB-mediated gene transcription (IC50 = 0.081 ± 0.04 μM). 666-15 also potently inhibited cancer cell growth without harming normal cells.In an in vivo MDA-MB-468 xenograft model, 666-15 completely suppressed the tumor growth without overt toxicity.

View Article: PubMed Central - PubMed

ABSTRACT
Recent studies have shown that nuclear transcription factor cyclic adenosine monophosphate response element binding protein (CREB) is overexpressed in many different types of cancers. Therefore, CREB has been pursued as a novel cancer therapeutic target. Naphthol AS-E and its closely related derivatives have been shown to inhibit CREB-mediated gene transcription and cancer cell growth. Previously, we identified naphthamide 3a as a different chemotype to inhibit CREB's transcription activity. In a continuing effort to discover more potent CREB inhibitors, a series of structural congeners of 3a was designed and synthesized. Biological evaluations of these compounds uncovered compound 3i (666-15) as a potent and selective inhibitor of CREB-mediated gene transcription (IC50 = 0.081 ± 0.04 μM). 666-15 also potently inhibited cancer cell growth without harming normal cells. In an in vivo MDA-MB-468 xenograft model, 666-15 completely suppressed the tumor growth without overt toxicity. These results further support the potential of CREB as a valuable cancer drug target.

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Related in: MedlinePlus

Compound 3i selectively inhibited CREB-mediatedgenetranscription. HEK 293T cells were transfected with indicated combinationsof plasmids. Then the cells were treated with different concentrationsof 3i before RLuc activity measurement. Forskolin (Fsk,10 μM) was added to CRE-Rluc only transfected cells at 30 minafter drug treatment to stimulate CREB’s activity. The RLucactivity was normalized to the protein concentration and presentedas relative luciferase unit (RLU)/μg protein.
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fig5: Compound 3i selectively inhibited CREB-mediatedgenetranscription. HEK 293T cells were transfected with indicated combinationsof plasmids. Then the cells were treated with different concentrationsof 3i before RLuc activity measurement. Forskolin (Fsk,10 μM) was added to CRE-Rluc only transfected cells at 30 minafter drug treatment to stimulate CREB’s activity. The RLucactivity was normalized to the protein concentration and presentedas relative luciferase unit (RLU)/μg protein.

Mentions: To investigate 3i’s selectivity on differenttranscription activators, we employed RLuc reporter assays to monitorindividual transcription factor activity in HEK 293T cells. VP16-CREBis a fusion protein by fusing the potent activation domain VP16 tothe full-length CREB. It requires CREB-CRE interaction for transcriptionalactivation, but it is a constitutively active transcription factorindependent of phosphorylation as opposed to wild type CREB.33 As shown in Table 1 andFigure 5, 3i potently (IC50 = 81 nM) and efficaciously inhibited CREB’s transcriptionactivity in HEK 293T cells. On the other hand, it showed much lessefficacious inhibition of VP16-CREB and p53-mediated gene transcription.And even this weak inhibition only occurred at high concentrations(>1 μM). In a separate transcription reporter assay withNF-κB,much higher concentrations of 3i were required to inhibitNF-κB-mediated gene transcription (IC50 = 5290 nM, Figure S2), which is distinct from 1 and its phosphate.32 Collectively, theseresults indicate that 3i selectively inhibited CREB-mediatedgene transcription.


Identification of a Potent Inhibitor of CREB-Mediated Gene Transcription with Efficacious in Vivo Anticancer Activity.

Xie F, Li BX, Kassenbrock A, Xue C, Wang X, Qian DZ, Sears RC, Xiao X - J. Med. Chem. (2015)

Compound 3i selectively inhibited CREB-mediatedgenetranscription. HEK 293T cells were transfected with indicated combinationsof plasmids. Then the cells were treated with different concentrationsof 3i before RLuc activity measurement. Forskolin (Fsk,10 μM) was added to CRE-Rluc only transfected cells at 30 minafter drug treatment to stimulate CREB’s activity. The RLucactivity was normalized to the protein concentration and presentedas relative luciferase unit (RLU)/μg protein.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493896&req=5

fig5: Compound 3i selectively inhibited CREB-mediatedgenetranscription. HEK 293T cells were transfected with indicated combinationsof plasmids. Then the cells were treated with different concentrationsof 3i before RLuc activity measurement. Forskolin (Fsk,10 μM) was added to CRE-Rluc only transfected cells at 30 minafter drug treatment to stimulate CREB’s activity. The RLucactivity was normalized to the protein concentration and presentedas relative luciferase unit (RLU)/μg protein.
Mentions: To investigate 3i’s selectivity on differenttranscription activators, we employed RLuc reporter assays to monitorindividual transcription factor activity in HEK 293T cells. VP16-CREBis a fusion protein by fusing the potent activation domain VP16 tothe full-length CREB. It requires CREB-CRE interaction for transcriptionalactivation, but it is a constitutively active transcription factorindependent of phosphorylation as opposed to wild type CREB.33 As shown in Table 1 andFigure 5, 3i potently (IC50 = 81 nM) and efficaciously inhibited CREB’s transcriptionactivity in HEK 293T cells. On the other hand, it showed much lessefficacious inhibition of VP16-CREB and p53-mediated gene transcription.And even this weak inhibition only occurred at high concentrations(>1 μM). In a separate transcription reporter assay withNF-κB,much higher concentrations of 3i were required to inhibitNF-κB-mediated gene transcription (IC50 = 5290 nM, Figure S2), which is distinct from 1 and its phosphate.32 Collectively, theseresults indicate that 3i selectively inhibited CREB-mediatedgene transcription.

Bottom Line: In a continuing effort to discover more potent CREB inhibitors, a series of structural congeners of 3a was designed and synthesized.Biological evaluations of these compounds uncovered compound 3i (666-15) as a potent and selective inhibitor of CREB-mediated gene transcription (IC50 = 0.081 ± 0.04 μM). 666-15 also potently inhibited cancer cell growth without harming normal cells.In an in vivo MDA-MB-468 xenograft model, 666-15 completely suppressed the tumor growth without overt toxicity.

View Article: PubMed Central - PubMed

ABSTRACT
Recent studies have shown that nuclear transcription factor cyclic adenosine monophosphate response element binding protein (CREB) is overexpressed in many different types of cancers. Therefore, CREB has been pursued as a novel cancer therapeutic target. Naphthol AS-E and its closely related derivatives have been shown to inhibit CREB-mediated gene transcription and cancer cell growth. Previously, we identified naphthamide 3a as a different chemotype to inhibit CREB's transcription activity. In a continuing effort to discover more potent CREB inhibitors, a series of structural congeners of 3a was designed and synthesized. Biological evaluations of these compounds uncovered compound 3i (666-15) as a potent and selective inhibitor of CREB-mediated gene transcription (IC50 = 0.081 ± 0.04 μM). 666-15 also potently inhibited cancer cell growth without harming normal cells. In an in vivo MDA-MB-468 xenograft model, 666-15 completely suppressed the tumor growth without overt toxicity. These results further support the potential of CREB as a valuable cancer drug target.

Show MeSH
Related in: MedlinePlus