Catalog No.S7152

C646 Chemical Structure

Molecular Weight(MW): 445.42

C646 is an inhibitor for histone acetyltransferase, and inhibits p300 with a Ki of 400 nM in a cell-free assay. Preferentially selective for p300 versus other acetyltransferases.

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Cited by 9 Publications

6 Customer Reviews

  • Phosphorylation of STAT6 in butyrate-treated M2-BMDMs. Western blotting was performed with anti-phospho-STAT6, STAT6, and β-actin. Data are representative of three independent experiments. M2:M2 macrophage; But:butyrate.

    Sci Rep, 2016, 6:24838.. C646 purchased from Selleck.

    A. Immunoprecipitation of HSP90 from NT, shHSF1 or shHSF1 Mec-1 cells treated with 20 μM, C646 for 24 hours followed by immunoblotting for acetyl lysine and HSP90 (top panel). Immunoprecipitation of CDC37 followed by immunoblot analysis of HSP90 and the indicated HSP90 client kinases (bottom panel).

    Oncotarget, 2015, 6(31):31767-79.. C646 purchased from Selleck.

  • (E) si-P300-3 and C646 separately suppressed the Res-induced mRNA expression of VEGFb, VEGFR1, and VEGFR2 in differentiated PC-12 cells (*P<0.05, **P<0.01, ***P<0.01).

    Front Neurosci, 2018, doi:10.3389/fnins.2018.00341. C646 purchased from Selleck.

    The expression of Dtprp in stromal cells at 96 h decreased in a dose-dependent manner when stromal cells were treated with histone acetyltransferase inhibitor C646.

    Biol Reprod, 2015, 93(1): 13. C646 purchased from Selleck.

  • Left: The protein level of acH4K5 in the DMSO and C646 5 µM groups. H4 was used as a loading control. Right: The expression level of cyclin D3 decreased in the C646 5 µM group compared with the DMSO group detected by Western blotting analysis. Protein lysates for Western blot analysis were obtained at 48 h after C646 treatment.

    Biol Reprod, 2015, 93(1): 13. C646 purchased from Selleck.

    C646 attenuates ETV1 expression and inactivates KIT-dependent pathways. GIST882 cells were treated with C646 (5-20 μmol/l) for 24 h. Imatinib (500 nmol/l) alone or in combination with C646 (15 μmol/l) was used for the combination study. DMSO was used as the vehicle control. The expression levels of ETV1 and KIT-dependent pathway-related proteins were analysed by western blotting. GAPDH was used as a reference. ETV1, ETS translocation variant 1; GIST, gastrointestinal stromal tumor; DMSO, dimethyl sulfoxide; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.

    Oncol Rep, 2016, 36(5):2763-2770.. C646 purchased from Selleck.

Purity & Quality Control

Choose Selective Histone Acetyltransferase Inhibitors

Biological Activity

Description C646 is an inhibitor for histone acetyltransferase, and inhibits p300 with a Ki of 400 nM in a cell-free assay. Preferentially selective for p300 versus other acetyltransferases.
Features Extensively used as a pharmacologic probe in cancer cells. Potential use for prostate and lung cancers.
p300/CBP [1]
(Cell-free assay)
400 nM(Ki)
In vitro

C646 is an inhibitor for histone acetyltransferase, inhibits p300 with a Ki of 400 nM and is selective versus other acetyltransferases. C646 produces 86% inhibition of p300 in vitro at 10 μM. C646 is a classical reversible p300 inhibitor. C646 treatment (25μM) reduces histone H3 and H4 acetylation levels and abrogates TSA-induced acetylation in cells. [1] C646 (20μM) induces apoptosis in androgen-sensitive and castration-resistant prostate cancer cell lines by interfering with AR and NF-kB pathways. [2] C646 blocks dynamic acetylation of H3K4me3 globally in mouse and fly cells, and locally across the promoter and start-site of inducible genes in the mouse, thereby disrupting RNA polymerase II association and the activation of these genes. [3]

In vivo C646 infused into the ILPFC immediately after weak extinction training enhances the consolidation of fear extinction memory. [4] C646 attenuates mechanical allodynia and thermal hyperalgesia, accompanied by a suppressed COX-2 expression, in the spinal cord. [5]


Kinase Assay:[1]
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Radioactive assay:

IC50 values for the putative p300 HAT inhibitors are determined using the direct radioactive assay described above. Reactions are performed in 20 mM HEPES (pH 7.9), and contained 5 mM DTT, 80μM EDTA, 40μg/ml BSA, 100μM H4-15, and 5 nM p300. Putative inhibitors are added over a range of concentrations, with DMSO concentration kept constant (<5%). Reactions are incubated at 30°C for 10 min, then initiated with addition of a 1:1 mixture of 12C-acetyl-CoA and 14C-acetyl-CoA to 20 mM. After 10 min at 30°C, reactions are quenched with 14% SDS (w/v). All concentrations are screened in duplicate. Gels are run, washed, dried, and exposed to a PhosphorImager plate, and production of Ac-H4-15 quantified to obtain IC50s.
Cell Research:[1]
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  • Cell lines: C3H10T1/2
  • Concentrations: ~25 μM
  • Incubation Time: 1 to 3 hr
  • Method: Histone acetylation assays in mouse cells. C3H10T1/2 mouse fibroblasts are grown in DMEM with 10% FCS at 37°C with 6% CO2. Confluent cultures are rendered quiescent in DMEM with 0.5% FCS for 18-20 hr prior to treatment. Cells are treated with the following compounds: TSA (10 ng/ml [33 nM]), C646 (25 μM), C37 (25 μM). Antibodies are used at the following concentrations: total H3 (1:10000; ab7834; Abcam); H4K12ac (1:2500; 06-761; Upstate). Rabbit anti-H3K9ac (1:10000) antibodies are generated in-house. Histones are isolated from cells by acid extraction, separated by SDS and acid-urea polyacrylamide gel electrophoresis and analyzed by western blotting.
    (Only for Reference)
Animal Research:[4]
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  • Animal Models: mouse
  • Formulation: 10% DMSO
  • Dosages: 2×0.75 μl injection volume in each case, 1.5 μg, administered over 2 min
  • Administration: infusion into ILPFC
    (Only for Reference)

Solubility (25°C)

In vitro DMSO 13 mg/mL (29.18 mM)
Water Insoluble
Ethanol Insoluble
In vivo Add solvents to the product individually and in order(Data is from Selleck tests instead of citations):
5% DMSO+30% PEG 300+ddH2O
For best results, use promptly after mixing.

* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.

Chemical Information

Molecular Weight 445.42


CAS No. 328968-36-1
Storage powder
in solvent
Synonyms N/A

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Tech Support

Answers to questions you may have can be found in the inhibitor handling instructions. Topics include how to prepare stock solutions, how to store inhibitors, and issues that need special attention for cell-based assays and animal experiments.

Handling Instructions

Tel: +1-832-582-8158 Ext:3

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Frequently Asked Questions

  • Question 1:

    I am planning to conduct IP studies in mice, any specific vehicle that you can recommend to me?

  • Answer:

    We found it can be dissolved in 5% DMSO+30% PEG 300+ddH2O at 1 mg/ml as a clear solution. It should be ok for i.p. injection.

Histone Acetyltransferase Signaling Pathway Map

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID