Catalog No.S1155

S3I-201 shows potent inhibition of STAT3 DNA-binding activity with IC50 of 86 μM in cell-free assays, and low activity towards STAT1 and STAT5.

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S3I-201 Chemical Structure

S3I-201 Chemical Structure
Molecular Weight: 365.36

Validation & Quality Control

Customer Product Validation(7)

Quality Control & MSDS

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Product Description

Biological Activity

Description S3I-201 shows potent inhibition of STAT3 DNA-binding activity with IC50 of 86 μM in cell-free assays, and low activity towards STAT1 and STAT5.
Targets STAT3 [1]
(Cell-free assay)
IC50 86 μM
In vitro S3I-201 inhibits growth and induces apoptosis preferentially in tumor cells that contain persistently activated Stat3 by inhibiting Stat3·Stat3 complex formation and Stat3 DNA-binding and transcriptional activitie. Moreover, S3I-201 also inhibits the expression of the Stat3-regulated genes encoding cyclin D1, Bcl-xL, and survivin. [1] S3I-201 inhibits breast carcinoma MDA-MB-435, MDA-MB-453 and MDA-MB-231 cell lines with IC50 of 100 μM. In addition, the cells with impaired TGF-β signaling are four times as sensitive to the STAT3 inhibitor S3I-201. [2] A recent study shows that S3I-201 potentiates the antiproliferative effect of cetuximab in HepG2 and Huh-7 cells via the STAT3 signalling pathway. [3]
Cell Data
Cell LinesAssay TypeConcentrationIncubation TimeFormulationActivity DescriptionPMID
BT474R MlXBSpVv[3Srb36gRZN{[Xl?NUC1eFc5PTBizszNM1vJRlExNTZyIHS=NGTmepFqdmirYnn0d{BUXEGWMzDhZ5Rqfmm2eR?=Mmf3NlU{Ojd3NkG=
GC M{m5PWdzd3e2aDDJcohq[mm2aX;uJGF{e2G7M3v4elUxNTF{NTFOwG0>MXy3NkBpMoK0ZZR1\W63YYTld{B1cGViY3XscEBoem:5dHigbY4h[SCmb4PlMYRmeGWwZHXueEBu[W6wZYK=NIXu[JozPTd5NEWwNy=>
H460 M1PTS2Fxd3C2b4Ppd{BCe3OjeR?=NUHyeoxIOTBywrDuUS=>NXjLRWJzOjUEoHi=MWTpcoR2[2W|IHPlcIwh[XCxcITvd4l{KGOxLYTy[YF1\WRid3n0bEBDTVp{M{W=MoruNlQ1PzJ3M{i=
H460 M{DJO2Fxd3C2b4Ppd{BCe3OjeR?=NGXN[HAyODEEoH7NNHHrRmgzPMLiaB?=NXr6OJNp\W6qYX7j[ZMh[2WubDDk[YF1cCClbz30doVifGWmIIfpeIghVFl{OUSwNFI>Mnj4NlQ1PzJ3M{i=
U373 MUHHdo94fGhiSX7obYJqfGmxbjDBd5NigQ>?MVmxNlUh|ryPMnvkNlQhcA>?NHLXfXRFVVORMWnkbZNzfXC2czDTWGFVOyC|aXfuZYxqdmdiYX7kJJBzd2yrZnXyZZRqd25?MYqyOFA4ODh{MB?=
T-cell MU\Hdo94fGhiSX7obYJqfGmxbjDBd5NigQ>?NXmySY5[UUN3ME21NEDPxE1?M1LYTVI1ODZ6N{Ox
H460 MoPzSpVv[3Srb36gRZN{[Xl?MYq1NE8yODBizszNMoLUOFghcA>?MkfFbY5pcWKrdIOgeIhmKFO2YYSzR{BqdmO{ZXHz[YQhdWmULUmyZUBmgHC{ZYPzbY9vM{KxWFI{QDJyMkW0
PLC/PRF/5 M3zvemdzd3e2aDDJcohq[mm2aX;uJGF{e2G7MX[xNFAhdk1?NHHwbpo1QCCqM13vZWROW09?M3Oxb4lvcGmkaYTzJJRp\SCLTD22JJN1cW23bHH0bY9vKHC{b33veIVlKGOnbHygdJJwdGmoZYLheIlwdg>?MV:yN|M3PDN6OR?=
 U-373 MGNYTP[|JXS3m2b4TvfIlkcXS7IFHzd4F6MmO1N{8yOCEQvF2=Mn3PNlQhcA>?MX;y[YR2[2W|IF\OMe6{NWmwZIXj[YQh[2WubDDu[ZVzd3SxeHnjbZR6MmPtNlA5QDh2MU[=
U373 MVPHdo94fGhiSX7obYJqfGmxbjDBd5NigQ>?M3;yV|czKGh?NGL0fW9KSzVyPUWyMlUh|ryPNH3r[ZgzODB5Mk[1Ni=>

... Click to View More Cell Line Experimental Data

In vivo S3I-201 (5 mg/kg, i.v. every 2 or every 3 days) shows the antitumor efficacy in mouse models with human breast tumor xenografts that harbor constitutively active Stat3. [1] S3I-201 treatment reduces Varicella-zoster virus (VZV) replication on the basis of the bioluminescence signal and the number of positive skin xenografts compared with DMSO-treated mice by inhibiting STAT3 phosphorylation. [4]
Features A chemical probe inhibitor of Stat3 activity.

Protocol(Only for Reference)

Kinase Assay: [1]

In vitro Stat3 DNA-binding assay and EMSA analysis Briefly, 100 mL of biotinyl-e-Ac-EPQpYEEIEL-OH (in 50 mM Tris/150 mM NaCl, pH 7.5) is added to each well of streptavidin-coated 96-well microtiter plates and incubated with shaking at 4 °C overnight. Then plates are rinsed with PBS/Tween 20 and then two times with 200 mL of BSA-T-PBS (0.2% BSA/0.1% Tween 20/PBS). Then 50 mL of Lck-SH2-GST fusion protein (6.4 ng/ml in BSA-T-PBS) is added to each well of the 96-well plate in the presence and absence of 50 mL of S3I-201 (for 30 and 100 mM final concentrations), and the plate is shaken at room temperature for 4 hours. After solutions are removed, each well is rinsed four times with BSA-T-PBS (200 mL), and 100 mL of polyclonal rabbit anti-GST antibody (100 ng/mL in BSA-T-PBS) is added to each well and incubated at 4 °C overnight. After washing with BSA-T-PBS, 100 mL of 200 ng/mL BSA-T-PBS horseradish peroxidase-conjugated mouse anti-rabbit antibody is added to each well and incubated for 45 minutes at room temperature. After four washing steps with BSA-T-PBS and three washing steps with PBS-T, 100 mL of peroxidase substrate is added to each well and incubated for 5-15 minutes. The peroxidase reaction is stopped by adding 100 mL of 1 M sulfuric acid solution, and absorbance is read at 450 nm with an ELISA plate rea

Cell Assay: [2]

Cell lines MDA-MB-435, MDA-MB-453 and MDA-MB-231 cells lines
Concentrations ~ 250 μM
Incubation Time 72 hours
Method The MTT assay is based on the conversion of the yellow tetrazolium salt MTT to purple formazan crystals by metabolically active cells. The MTT assay provides a quantitative determination of viable cells. Cells are seeded in 96-well microplates in complete culture medium in the absence or presence of increasing serial dosages of S3I-201 as indicated. At 72 hours after culture, the number of viable cells is measured by adding 100 μL/well of 2 mg/mL MTT solution. After 2 hours, the medium is removed, and the formazan crystals are dissolved by adding 100 μL dimethylsulfoxide per well. The absorbance is read at 590 nm with an enzyme-linked immunosorbent assay reader. Each treatment point is performed in 10 wells or sextuplicate.

Animal Study: [1]

Animal Models Human breast cancer MDA-MB-231 cells are injected s.c. into the left flank of athymic nu/nu mice.
Formulation S3I-201 is formulated in DMSO.
Dosages ≤5 mg/kg
Administration Administered via i.v.

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

SpeciesMouseRatRabbitGuinea pigHamsterDog
Weight (kg)
Body Surface Area (m2)0.0070.0250.
Km factor36128520
Animal A (mg/kg) = Animal B (mg/kg) multiplied by  Animal B Km
Animal A Km

For example, to modify the dose of resveratrol used for a mouse (22.4 mg/kg) to a dose based on the BSA for a rat, multiply 22.4 mg/kg by the Km factor for a mouse and then divide by the Km factor for a rat. This calculation results in a rat equivalent dose for resveratrol of 11.2 mg/kg.

Rat dose (mg/kg) = mouse dose (22.4 mg/kg) ×  mouse Km(3)  = 11.2 mg/kg
rat Km(6)


[1] Siddiquee K, et al. Proc Natl Acad Sci U S A, 2007, 104(18), 7391-7396.

[2] Lin L, et al. Oncogene, 2009, 28(7), 961-972.

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Chemical Information

Download S3I-201 SDF
Molecular Weight (MW) 365.36


CAS No. 501919-59-1
Storage 3 years -20℃powder
6 months-80℃in solvent
Synonyms NSC 74859
Solubility (25°C) * In vitro DMSO 73 mg/mL (199.8 mM)
Water <1 mg/mL (<1 mM)
Ethanol <1 mg/mL (<1 mM)
In vivo 5% DMSO, 95% PEG 300 15 mg/mL
* <1 mg/ml means slightly soluble or insoluble.
* 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 Name 2-hydroxy-4-(2-(tosyloxy)acetamido)benzoic acid

Customer Product Validation (7)

Click to enlarge
Source Clin Cancer Res 2013 19(6), 1422-32. S3I-201 purchased from Selleck
Method Histopathologic analysis
Cell Lines BCR-ABL1-positive leukemia UPN1 cells
Concentrations 30 mg/kg
Incubation Time 28 days
Results Histopathologic analysis of vehicle-treated mice revealed infiltration of bone marrow with BCR-ABL1-positive leukemia UPN1 cells; however, cotreatment with ponatinib and vismodegib showed normal hematopoiesis in the bone marrow cavity.

Click to enlarge
Source Carcinogenesis 2013 34(9), 1994-9. S3I-201 purchased from Selleck
Method Western blot
Cell Lines MDA231 cells
Incubation Time 4 h
Results Inhibition of STAT3 activation with S3I-201 in the presence of IL6 leads to a loss of phospho-STAT3, which leads to reduced WASF3 levels. However, inhibition of SRC or EGFR activation in IL6-treated cells with Dasatinib or Gefitinib could not block IL6-induced JAK2/STAT3 phosphorylation and WASF3 protein levels.

Click to enlarge
Source J Biol Chem 2013 288, 26167-76. S3I-201 purchased from Selleck
Method Western blot
Cell Lines adherent glioma CSCs
Concentrations 30, 100, 300 uM
Incubation Time 2 h
Results Both WP1066 and S3I-201 were extremely effective in inhibiting STAT3 tyrosine phosphorylation in CSCs, with nearly complete inhibition of pSTAT3 at 50 μM WP1066 and 300 μM S3I-201.

Click to enlarge
Source Mol Cancer 2014 13:176. S3I-201 purchased from Selleck
Method Colony formation assay
Cell Lines A549 cells
Concentrations 100 uM
Incubation Time 14 days
Results Colony formation assays were performed in the presence or absence of the inhibitors U0126, PP1, or S3I-201. Significantly, S3I-201 reduced the number and sizes of colonies of A549 cells carrying KIF5B-RET.

Click to enlarge
Source Microbes Infect 2014 16(1), 17-27. S3I-201 purchased from Selleck
Method Western blot
Cell Lines A549 cells
Concentrations 10-100 uM
Incubation Time 24 h
Results To corroborate this finding at the protein level, and to confirm that the apoptosis-related proteins participate in this process, Western blots were performed using total protein extracted from A549 cells. A549 cells were treated with increasing concentrations of NSC 74859 (10–100 uM) for 24 h. NSC 74859 at 100 uM completely suppressed STAT3 phosphorylation without inducing A549 cell apoptosis.

Click to enlarge
Source Int Immunopharmacol 2014 20(1), 117-23. S3I-201 purchased from Selleck
Method Western blot
Cell Lines Dendritic cells
Concentrations 100 uM
Incubation Time 6 days
Results The expression and phosphorylation of STAT3 was decreased significantly by the inhibitor NSC74859. These results indicated that it obtained an efficient and stable STAT3 blockade in the DCs. PD-L1 expression in STAT3-blockaded DCs by western blot. The results indicated that compared with control DCs, the expression of PD-L1 in TGF-β-DCs was significantly increased. After the addition of NSC74859, the elevated PD-L1 expression by TGF-β was obviously inhibited (P < 0.01).

Click to enlarge
Source S3I-201 purchased from Selleck
Method MTT
Cell Lines monolayer and adherent CSC
Concentrations 30, 100, 300 uM
Incubation Time 72 h
Results flow cytometric analysis of annexin V-stained cells demonstrated that treatment with the STAT3 inhibitor WP1066 or S3I-201 had a greater effect on the induction of apoptosis in adherent CSCs than in glioma monolayers.

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.

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID
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