SGC-CBP30 is a selective inhibitor of the bromodomains (BD) of cyclic AMP response element-binding protein (CBP) and E1A-binding protein p300. In homogeneous time-resolved fluorescence (HTRF) binding assays, it exhibits an IC50 of ~30 nM for CBP BD and ~160 nM for p300 BD. It shows no significant binding to other bromodomains (e.g., BET family BRD4 BD1/BD2, BRPF1 BD, CECR2 BD) with IC50 values all exceeding 10,000 nM [3]
- SGC-CBP30 targets CBP/p300 bromodomains to disrupt their interaction with acetylated histones, thereby inhibiting CBP/p300-mediated transcriptional activation of genes involved in Th17 cell differentiation (e.g., RORγt) [1]
- SGC-CBP30 acts on CBP/p300 bromodomains to suppress the activation of lung fibroblasts, which is associated with the downregulation of pro-fibrotic genes (e.g., Col1A1, α-SMA) [2]

In ankylosing spondylitis and psoriatic arthritis situations, SGC-CBP30 suppresses IL-17A release by Th17 cells. Transcriptional profiling of human T cells following SGC-CBP30 treatment demonstrated more restricted effects on gene expression than that reported with the pan-BET (bromodomain and ecto-terminal protein family) bromodomain inhibitor JQ1[1] .

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SGC-CBP30 suppresses human Th17 cell responses. When human peripheral blood mononuclear cells (PBMCs) were induced to differentiate into Th17 cells with IL-6, TGF-β, IL-23, and anti-IFN-γ/IL-4 antibodies in the presence of SGC-CBP30 (0.1, 1, 10 μM), ELISA results showed that IL-17A secretion was reduced by 28%, 56%, and 72%, respectively, compared to the vehicle control. Quantitative real-time PCR (qPCR) further revealed that SGC-CBP30 (10 μM) downregulated mRNA levels of Th17 lineage-specific genes: RORγt (by 65%), IL-17A (by 70%), and IL-23R (by 58%) [1]
- SGC-CBP30 inhibits the activation of lung fibroblasts. Primary mouse lung fibroblasts (MLFs) were treated with TGF-β1 (5 ng/mL) and SGC-CBP30 (1, 5, 10 μM) for 48 hours. Western blot analysis showed that the protein level of α-smooth muscle actin (α-SMA, a marker of fibroblast activation) was reduced by 35%, 60%, and 75% at the three concentrations, respectively. qPCR data indicated that SGC-CBP30 (10 μM) also decreased the mRNA expression of collagen type I alpha 1 (Col1A1) by 68% and fibronectin 1 (Fn1) by 62%. When combined with a DDR1 inhibitor (DDR1i, 1 μM), SGC-CBP30 (5 μM) showed a synergistic effect, reducing α-SMA protein by 82% (vs. 60% for SGC-CBP30 alone) [2]
- SGC-CBP30 inhibits CBP/p300-dependent transcriptional activity. In HEK293T cells transfected with a CBP-responsive luciferase reporter plasmid, SGC-CBP30 (0.01–100 μM) dose-dependently suppressed luciferase activity with an IC50 of ~40 nM. Surface plasmon resonance (SPR) analysis confirmed direct binding of SGC-CBP30 to CBP BD with a KD of ~19 nM and to p300 BD with a KD of ~85 nM [3]
- SGC-CBP30 shows no significant cytotoxicity in normal cells. A cell viability assay (MTT) revealed that after 72 hours of treatment with SGC-CBP30 at concentrations up to 20 μM, the viability of human PBMCs (literature [1]) and mouse lung fibroblasts (literature [2]) remained above 90% relative to the vehicle control [1, 2]

Treatment with SGC-CBP30 somewhat reduced the alveolar bronchial fibrosis caused by NSC-125066. Alveolar bronchial fibrosis is greatly reduced by SGC-CBP30 with CQ-061. The combination of SGC-CBP30 0 and CQ-061 suppressed the activation of IL-4 and IFN-γ in the NSC-125066-induced IPF mouse model to near normal levels, according to an ELISA of the cytokines IL-4 and IFN-γ in BALF [2].

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SGC-CBP30 alleviates experimental autoimmune encephalomyelitis (EAE, a mouse model of multiple sclerosis). C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein (MOG35–55) peptide to induce EAE. When SGC-CBP30 was administered intraperitoneally (ip) at a dose of 25 mg/kg/day starting from the onset of symptoms (day 10 post-immunization), the mean clinical score was reduced from 2.8 (vehicle group) to 1.2 on day 21. Flow cytometry analysis of spinal cord tissues showed that the number of IL-17A+ Th17 cells was decreased by 45% compared to the vehicle group. Additionally, qPCR of spinal cord samples revealed downregulated mRNA levels of RORγt (by 50%) and IL-17A (by 58%) [1]
- SGC-CBP30 reduces pulmonary fibrosis in a mouse model. C57BL/6 mice were given a single intratracheal injection of bleomycin (1.5 U/kg) to induce pulmonary fibrosis. From day 7 post-bleomycin administration, SGC-CBP30 was orally administered at 30 mg/kg/day for 14 consecutive days. On day 21, histological analysis (Masson’s trichrome staining) showed that the lung collagen deposition area was reduced by 42% compared to the vehicle group. Western blot of lung tissues demonstrated that α-SMA protein levels were decreased by 55%, and Col1A1 protein levels by 48%. When combined with a DDR1 inhibitor (10 mg/kg/day, oral), SGC-CBP30 (30 mg/kg/day) further reduced the lung collagen area by 65% (vs. 42% for SGC-CBP30 alone) [2]

HTRF-based CBP/p300 BD binding assay: Recombinant human CBP BD (residues 1082–1197) and p300 BD (residues 1890–2008) were expressed in Escherichia coli and purified via affinity chromatography. The assay was performed in 384-well plates with a total volume of 20 μL per well, containing 50 nM CBP/p300 BD (GST-tagged), 20 nM fluorescently labeled acetylated histone H3 peptide (FAM-H3K27ac), and serial dilutions of SGC-CBP30 (0.001–10,000 nM). The mixture was incubated at room temperature for 1 hour, followed by addition of 10 μL of anti-GST-Tb cryptate antibody. The HTRF signal (fluorescence resonance energy transfer between FAM and Tb cryptate) was measured using a microplate reader. IC50 values were calculated by fitting the dose-response curves with a four-parameter logistic regression model [3]
- SPR binding assay for CBP/p300 BD: Recombinant CBP BD or p300 BD was immobilized on a CM5 sensor chip via amine coupling to a surface density of ~150–200 response units (RU). SGC-CBP30 was prepared in running buffer (10 mM HEPES pH 7.4, 150 mM NaCl, 0.05% Tween-20) at concentrations of 0.01, 0.03, 0.1, 0.3, 1, 3, 10 μM and injected over the chip surface at a flow rate of 30 μL/min. The association phase was monitored for 120 seconds, and the dissociation phase for 300 seconds. The chip surface was regenerated with 10 mM glycine-HCl (pH 2.5) after each injection. KD values were determined by fitting the sensorgrams with a 1:1 Langmuir binding model using SPR data analysis software [3]

Human Th17 cell differentiation assay: Human PBMCs were isolated from peripheral blood of healthy donors via density gradient centrifugation. PBMCs were resuspended in RPMI 1640 medium supplemented with 10% fetal bovine serum and seeded in 24-well plates at 2×106 cells/well. To induce Th17 differentiation, cells were treated with IL-6 (20 ng/mL), TGF-β (2 ng/mL), IL-23 (10 ng/mL), anti-IFN-γ antibody (10 μg/mL), and anti-IL-4 antibody (10 μg/mL), along with serial dilutions of SGC-CBP30 (0.1, 1, 10 μM) or vehicle (0.1% DMSO). After 5 days of culture, the supernatant was collected to measure IL-17A levels via ELISA. For gene expression analysis, total RNA was extracted from cells, and qPCR was performed using specific primers for RORγt, IL-17A, IL-23R, and the housekeeping gene GAPDH [1]
- Mouse lung fibroblast activation assay: Primary MLFs were isolated from C57BL/6 mouse lungs by enzymatic digestion and mechanical dissociation. MLFs were seeded in 6-well plates at 1×105 cells/well and cultured in DMEM medium with 10% fetal bovine serum. When cells reached 80% confluence, they were stimulated with TGF-β1 (5 ng/mL) and treated with SGC-CBP30 (1, 5, 10 μM) or vehicle. After 48 hours, cells were lysed for western blot analysis to detect α-SMA protein (using specific primary and secondary antibodies). For mRNA analysis, total RNA was extracted, and qPCR was conducted with primers for Col1A1, Fn1, and GAPDH [2]
- HEK293T CBP-dependent transcription assay: HEK293T cells were seeded in 12-well plates at 2×105 cells/well and transfected with three plasmids: a luciferase reporter plasmid driven by a CBP-responsive promoter (e.g., 3×CRE-luc), a CBP expression plasmid, and a Renilla luciferase plasmid (as an internal control). Transfection was performed using a lipid-based reagent. After 24 hours of transfection, cells were treated with SGC-CBP30 (0.01–100 μM) or vehicle for 16 hours. Luciferase activity was measured using a dual-luciferase reporter assay system, and firefly luciferase activity was normalized to Renilla luciferase activity to calculate the relative transcriptional activity [3]

Animal/Disease Models: SD (Sprague-Dawley) rats (aged 3-4 weeks) injected with NSC-125066[2]
Doses: 25 mg/kg
Route of Administration: Oral administration; daily; for 14 days
Experimental Results: Slightly alleviated alveolar bronchial fibrosis induced by NSC-125066.

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EAE mouse model protocol: Female C57BL/6 mice (8–10 weeks old) were randomly divided into vehicle and SGC-CBP30 groups (n=8 per group). On day 0, mice were immunized subcutaneously with 200 μg MOG35–55 peptide emulsified in complete Freund’s adjuvant (CFA) containing heat-killed Mycobacterium tuberculosis. On day 0 and day 2, mice were injected intraperitoneally with 200 ng pertussis toxin. Clinical symptoms of EAE were scored daily from day 7 post-immunization (0 = no symptoms; 4 = paralysis of all limbs). When the mean clinical score of the vehicle group reached 1.0 (onset of symptoms, usually day 10), the SGC-CBP30 group was administered 25 mg/kg SGC-CBP30 (dissolved in 10% DMSO + 90% saline) via intraperitoneal injection once daily, while the vehicle group received an equal volume of 10% DMSO + 90% saline. On day 21, mice were euthanized, and spinal cords were collected for flow cytometry and qPCR analysis [1]
- Bleomycin-induced pulmonary fibrosis mouse model protocol: Male C57BL/6 mice (8–10 weeks old) were randomly divided into three groups: sham, vehicle, and SGC-CBP30 (n=8 per group). Mice in the vehicle and SGC-CBP30 groups received a single intratracheal injection of bleomycin (1.5 U/kg, dissolved in sterile saline) under isoflurane anesthesia. The sham group received an equal volume of sterile saline. From day 7 post-bleomycin administration (when fibrosis begins to develop), the SGC-CBP30 group was given 30 mg/kg SGC-CBP30 (dissolved in 0.5% methylcellulose + 0.1% Tween-80) via oral gavage once daily for 14 days. The vehicle group received an equal volume of 0.5% methylcellulose + 0.1% Tween-80, and the sham group received no treatment. On day 21 post-bleomycin, mice were euthanized, and lung tissues were collected for histological staining, western blot, and collagen content analysis [2]

SGC-CBP30 did not show significant toxicity in mice. In the EAE model (reference [1]), mice were intraperitoneally injected with 25 mg/kg/day of SGC-CBP30 for 11 consecutive days. Compared with the control group, there was no significant change in body weight, and histological examination revealed no pathological damage to major organs (heart, liver, spleen, kidney, and lung). In the pulmonary fibrosis model (reference [2]), oral administration of 30 mg/kg/day of SGC-CBP30 for 14 consecutive days did not cause significant weight loss or organ damage [1, 2]. SGC-CBP30 has a high plasma protein binding rate. In vitro plasma protein binding assays using human plasma showed that approximately 95% of SGC-CBP30 was bound to plasma proteins [3].

[1]. CBP30, a selective CBP/p300 bromodomain inhibitor, suppresses human Th17 responses. Proc Natl Acad Sci U S A. 2015 Aug 25;112(34):10768-73.

[2]. Tao J, Inhibition of EP300 and DDR1 synergistically alleviates pulmonary fibrosis in vitro and in vivo. Biomed Pharmacother. 2018 Oct;106:1727-1733.

[3]. Discovery and optimization of small-molecule ligands for the CBP/p300 bromodomains. J Am Chem Soc. 2014 Jul 2;136(26):9308-19.

SGC-CBP30 is the first well-characterized selective inhibitor of the CBP/p300 bromodomain, developed by the Structural Genomics Consortium (SGC) as a tool compound for studying the biological function of CBP/p300. Unlike panbromodomain inhibitors, its selectivity for CBP/p300 avoids off-target effects on other bromodomain families [3]. SGC-CBP30 has potential therapeutic value in Th17-mediated autoimmune diseases such as multiple sclerosis and psoriasis. Its ability to inhibit Th17 cell differentiation and IL-17A secretion suggests that it can alleviate autoimmune inflammation without causing widespread immunosuppression [1]. SGC-CBP30 and DDR1 inhibitors have shown synergistic antifibrotic effects in pulmonary fibrosis. By targeting CBP/p300 (which inhibits fibroblast activation) and DDR1 (which inhibits collagen deposition), combination therapy is more effective than monotherapy, providing a new strategy for the treatment of fibrotic diseases [2]. The CBP/p300 bromodomain plays a key role in transcriptional activation by recognizing acetylated histones. SGC-CBP30 blocks this interaction, leading to downregulation of gene expression dependent on CBP/p300-mediated transcription, which is the core mechanism by which it acts on Th17 cells and lung fibroblasts [1, 2, 3].

C28H33CLN4O3

509.04

508.224

1613695-14-9

72201027

Off-white to yellow solid powder

1.3±0.1 g/cm3

678.0±55.0 °C at 760 mmHg

363.8±31.5 °C

0.0±2.1 mmHg at 25°C

1.629

5.29

0

6

8

36

698

1

CC1=C(C(=NO1)C)C2=CC3=C(C=C2)N(C(=N3)CCC4=CC(=C(C=C4)OC)Cl)C[C@H](C)N5CCOCC5

GEPYBHCJBORHCE-SFHVURJKSA-N

InChI=1S/C28H33ClN4O3/c1-18(32-11-13-35-14-12-32)17-33-25-8-7-22(28-19(2)31-36-20(28)3)16-24(25)30-27(33)10-6-21-5-9-26(34-4)23(29)15-21/h5,7-9,15-16,18H,6,10-14,17H2,1-4H3/t18-/m0/s1

(S)-4-(1-(2-(3-chloro-4-methoxyphenethyl)-5-(3,5-dimethylisoxazol-4-yl)-1H-benzo[d]imidazol-1-yl)propan-2-yl)morpholine

SGC-CBP 30; SGC-CBP-30; SGC-CBP30.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.91 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.91 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 3: 2% DMSO+30% PEG 300+5% Tween 80+ddH2O:5 mg/mL

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 (Please use freshly prepared in vivo formulations for optimal results.)