| Size | Price | Stock | Qty |
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| 2mg |
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Purity: ≥98%
STA-21 (NSC628869; Ochromycinone; STA21; Rac-STA-21) is a potent STAT3 inhibitor and natural antibiotic with anticancer and antimicrobial activity. It inhibits STAT3 with IC50 of 12.2 μM in DU145 cells. In cells, STA-21 inhibits Stat3 DNA binding activity, Stat3 dimerization, and Stat3-dependent luciferase activity. STA-21 remarkably inhibits the growth and the survival of the breast carcinoma cells MDA-MB-231, MDA-MB-435s, and MDA-MB-468 that express persistently activated Stat3. In RH30 and RD2 cells, STA-21 also inhibits cell viability and growth and induced apoptosis through caspases 3, 8 and 9 pathways
| Targets |
STA-21 targets signal transducer and activator of transcription 3 (STAT3) (IC50 = 4.8 μM for STAT3 DNA-binding activity; IC50 = 5.2 μM for STAT3 phosphorylation inhibition) [1]
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| ln Vitro |
STAT3 dimerization, STAT3-dependent luciferase activity, and STAT3 DNA binding activity are all inhibited by STA-21. Moreover, STA-21 decreased the survival of breast cancer cells that expressed constitutive STAT3 signaling, while it had no effect on those that did not [2].
In human breast cancer cell lines with constitutively activated STAT3 (MDA-MB-468, MDA-MB-231, MCF-7), STA-21 (2–20 μM) inhibits cell proliferation in a dose-dependent manner, with IC50 values of 5.6 μM (MDA-MB-468), 6.3 μM (MDA-MB-231), and 8.9 μM (MCF-7) [1] - It blocks STAT3 signaling: reduces phosphorylation of STAT3 (Tyr705) (Western blot), inhibits STAT3 nuclear translocation (immunofluorescence microscopy), and abrogates STAT3 DNA-binding activity (electrophoretic mobility shift assay, EMSA) [1] - It downregulates STAT3 target oncogenes at mRNA and protein levels: Bcl-2 (reduced by ~60% at 10 μM), Survivin (reduced by ~55% at 10 μM), and Cyclin D1 (reduced by ~50% at 10 μM) (qRT-PCR and Western blot) [1] - In MDA-MB-468 cells, STA-21 (10 μM) induces apoptosis (Annexin V-FITC/PI staining shows apoptotic rate ~42%) and reduces colony formation (colony number reduced by ~68% vs. vehicle control) [1] - It shows no significant inhibition of STAT1 or STAT5 DNA-binding activity at concentrations up to 20 μM, indicating selectivity for STAT3 [1] |
| ln Vivo |
In previous animal study, IL-1Ra-KO mice were treated with i.p. injections of STA-21 at 0.5 mg/kg 3 times per week for 3 weeks. Results showed that STA-21 could suppress inflammatory arthritis in IL-1Ra-KO mice. The Th17 cell proportion decreased and the proportion of Treg cells expressing FoxP3 was increased in the spleens of STA-21-treated mice markedly. Moreover, the adoptive transfer of CD4+CD25+ T cells from STA-21-treated IL-1Ra-KO mice suppressed inflammatory arthritis markedly.
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| Enzyme Assay |
STAT3 DNA-binding activity assay: Recombinant human STAT3 protein (3 μM) was incubated with biotin-labeled STAT3-responsive DNA probe (from the Bcl-2 promoter) and reaction buffer (20 mM Tris-HCl pH 7.6, 100 mM NaCl, 1 mM DTT, 5% glycerol) at room temperature for 30 minutes. STA-21 (0.5–20 μM) was added 10 minutes before probe addition. DNA-protein complexes were separated by 6% non-denaturing polyacrylamide gel electrophoresis, transferred to a nylon membrane, and detected with streptavidin-horseradish peroxidase conjugate. Inhibition rate was quantified by densitometric analysis, and IC50 was determined by nonlinear regression [1]
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| Cell Assay |
Breast cancer cell proliferation assay: MDA-MB-468/MDA-MB-231/MCF-7 cells (5×10³ per well) were seeded in 96-well plates and allowed to adhere overnight. STA-21 (2–20 μM) was added, and cells were incubated at 37°C with 5% CO2 for 72 hours. Cell viability was measured by MTT assay, and IC50 values were calculated from dose-response curves [1]
- STAT3 signaling and target gene assay: MDA-MB-468 cells (1×10⁶ per well) were seeded in 6-well plates, treated with STA-21 (5–10 μM) for 24 hours, and lysed in RIPA buffer. Western blot detected p-STAT3 (Tyr705), STAT3, Bcl-2, Survivin, Cyclin D1, and GAPDH. For mRNA analysis, total RNA was extracted, reverse-transcribed to cDNA, and qRT-PCR was performed to quantify target gene expression [1] - Apoptosis and clonogenic assay: For apoptosis, MDA-MB-468 cells (1×10⁵ per well) were treated with STA-21 (10 μM) for 24 hours, stained with Annexin V-FITC and PI, and analyzed by flow cytometry. For clonogenic assay, cells (1×10³ per well) were seeded in 6-well plates, treated with STA-21 (2–10 μM) for 14 days (medium refreshed every 3 days), stained with crystal violet, and colonies with >50 cells were counted [1] - STAT3 nuclear translocation assay: MDA-MB-468 cells (1×10⁴ per well) were seeded on coverslips, treated with STA-21 (10 μM) for 6 hours, fixed with 4% paraformaldehyde, permeabilized, and incubated with STAT3-specific primary antibody and fluorescent secondary antibody. Nuclei were stained with DAPI, and STAT3 localization was observed under a confocal microscope [1] |
| Animal Protocol |
Dissolved in saline; 0.5 mg/kg; i.p. injection
IL-1Ra–KO mice |
| Toxicity/Toxicokinetics |
In vitro toxicity: STA-21 at concentrations up to 20 μM had no significant cytotoxicity to normal human mammary epithelial cells (HMEC) (cell viability >85%, compared with the solvent control group) [1]
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| References |
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| Additional Infomation |
See also: Ochromycinone (note moved to).
STA-21 is a small molecule inhibitor of STAT3 discovered through virtual database screening[1] - Its mechanism of action involves binding to the SH2 domain of STAT3, preventing STAT3 dimerization and subsequent nuclear translocation, thereby inhibiting STAT3-mediated transcription of oncogenes[1] - It is selective for STAT3, superior to other members of the STAT family (STAT1, STAT5), and does not affect the activity of irrelevant transcription factors (e.g., NF-κB, AP-1) at therapeutic concentrations[1] - Preclinical in vitro efficacy in STAT3-activated breast cancer cell lines supports its potential as a STAT3-driven therapeutic for malignancies[1] |
| Molecular Formula |
C19H14O4
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| Molecular Weight |
306.31
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| Exact Mass |
306.089
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| CAS # |
111540-00-2
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| Related CAS # |
(+)-Ochromycinone;28882-53-3
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| PubChem CID |
363709
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| Appearance |
Light yellow to yellow solid powder
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| LogP |
2.932
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| Hydrogen Bond Donor Count |
1
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| Hydrogen Bond Acceptor Count |
4
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| Rotatable Bond Count |
0
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| Heavy Atom Count |
23
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| Complexity |
554
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| Defined Atom Stereocenter Count |
0
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| InChi Key |
ZAWXOCUFQSQDJS-UHFFFAOYSA-N
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| InChi Code |
InChI=1S/C19H14O4/c1-9-7-10-5-6-12-17(15(10)14(21)8-9)19(23)11-3-2-4-13(20)16(11)18(12)22/h2-6,9,20H,7-8H2,1H3
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| Chemical Name |
8-hydroxy-3-methyl-3,4-dihydrotetraphene-1,7,12(2H)-trione
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| Synonyms |
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month |
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| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
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| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 1.67 mg/mL (5.45 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 16.7 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 3.2647 mL | 16.3233 mL | 32.6467 mL | |
| 5 mM | 0.6529 mL | 3.2647 mL | 6.5293 mL | |
| 10 mM | 0.3265 mL | 1.6323 mL | 3.2647 mL |
*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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