For research use only.

Catalog No.S1155 Synonyms: NSC 74859

104 publications

S3I-201 Chemical Structure

Molecular Weight(MW): 365.36

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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10mM (1mL in DMSO) USD 78 In stock
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Selleck's S3I-201 has been cited by 104 publications

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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.
Features A chemical probe inhibitor of Stat3 activity.
STAT3 [1]
(Cell-free assay)
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 Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID
BT474R  M2PvTWZ2dmO2aX;uJGF{e2G7 MXy1NEDPxE1? NILldnIyOC14MDDk Ml;JbY5pcWKrdIOgV3RCXDNiYXP0bZZqfHl? MV2yOVMzPzV4MR?=
GH3 MYPHdo94fGhiSX7obYJqfGmxbjDBd5NigQ>? M1jLelUxNTF{NTFOwG0> MnvOO|IhcA>? NGHmR3pifHSnboXheIV{KHSqZTDj[YxtKGe{b4f0bEBqdiCjIHTvd4Uu\GWyZX7k[Y51KG2jbn7ldi=> MVGyOVc4PDVyMx?=
GC  NEHBXnBIem:5dHigTY5pcWKrdHnvckBCe3OjeR?= MU[1NE0yOjVizszN M{Hud|czKGh? MmTCZZR1\W63YYTld{B1cGViY3XscEBoem:5dHigbY4h[SCmb4PlMYRmeGWwZHXueEBu[W6wZYK= MnL0NlU4PzR3MEO=
H460  MkL4RZBweHSxc3nzJGF{e2G7 MkTqNVAxyqCwTR?= M2LSRlI1yqCq MXPpcoR2[2W|IHPlcIwh[XCxcITvd4l{KGOxLYTy[YF1\WRid3n0bEBDTVp{M{W= NHT5T3czPDR5MkWzPC=>
A459 M4\IUmFxd3C2b4Ppd{BCe3OjeR?= NXf6d4lZOTBywrDuUS=> Mn;HNlTDqGh? NW\ENIk{cW6mdXPld{Bk\WyuIHHwc5B1d3OrczDjc{11emWjdHXkJJdqfGhiQlXaNlM2 MlTCNlQ1PzJ3M{i=
H460  NWXxVlRLSXCxcITvd4l{KEG|c3H5 MUKxNFDDqG6P M1rVbFI1yqCq MoHX[Y5p[W6lZYOgZ4VtdCCmZXH0bEBkdy22cnXheIVlKHerdHigUHkzQTRyMEK= NWLuRo5WOjR2N{K1N|g>
MT-2 MVLBdI9xfG:|aYOgRZN{[Xl? MormO|UuOzByIN88US=> MX:yOE81QCCq M3HkN5N2eHC{ZYPz[ZMh[2WubDDwdo9tcW[ncnH0bY9vKGmwIHGg[I9{\S2mZYDlcoRmdnRibXHucoVzKGGwZDDpcoR2[2W|IHPlcIwh[XCxcITvd4l{yqB? NHnkXmEzPDB7MEm5OS=>
HUT-102 MonqRZBweHSxc3nzJGF{e2G7 NGPR[o84PS1|MECg{txO NH;VPJYzPC92ODDo NIfH[pV{fXCycnXzd4V{KGOnbHygdJJwdGmoZYLheIlwdiCrbjDhJIRwe2VvZHXw[Y5l\W62IH3hco5meiCjbnSgbY5lfWOnczDj[YxtKGGyb4D0c5Nqe8Li NXT0UGM2OjRyOUC5PVU>
U373  M4LSeWdzd3e2aDDJcohq[mm2aX;uJGF{e2G7 M1PZc|EzPSEQvF2= NF3VNGczPCCq NIH5V|JFVVOR NXOyVYk{\Gm|coXweJMhW1SDVEOgd4lodmGuaX7nJIFv\CCycn;sbYZmemG2aX;u M2fRdFI1ODdyOEKw
T-cell  M3K3Umdzd3e2aDDJcohq[mm2aX;uJGF{e2G7 MXLJR|UxRTVyIN88US=> MYmyOFA3QDd|MR?=
H1299 M{\zNWZ2dmO2aX;uJGF{e2G7 NG\KTnM2OC9zMECg{txO Mon5OFghcA>? M4jYcJN2eHC{ZYPz[ZMhdWmULUmyZUBmgHC{ZYPzbY9vKGSxc3Wt[IVx\W6mZX70cJk> NIO0[XczOzh{MEK1OC=>
H460  NEHHcGZHfW6ldHnvckBCe3OjeR?= NXXQZmNMPTBxMUCwJO69VQ>? NELXe4o1QCCq MYfpcohq[mm2czD0bIUhW3SjdEPDJIlv[3KnYYPl[EBucVJvOULhJIV5eHKnc4Ppc44> MWmyN|gzODJ3NB?=
PLC/PRF/5  MlOxS5Jwf3SqIFnubIljcXSrb36gRZN{[Xl? Mn;5NVAxKG6P MXq0PEBp MV7EUXNQ NXPTblhzcW6qaXLpeJMhfGinIFnMMVYhe3SrbYXsZZRqd25icILvcY91\WRiY3XscEBxem:uaX\ldoF1cW:w NVfQT4RTOjN|NkSzPFk>
Huh7 NH\CVmtIem:5dHigTY5pcWKrdHnvckBCe3OjeR?= NFn3OFcyODBibl2= M3e2UFQ5KGh? M2XUe2ROW09? NYnNOYFicW6qaXLpeJMhfGinIFnMMVYhe3SrbYXsZZRqd25icILvcY91\WRiY3XscEBxem:uaX\ldoF1cW:w MmLLNlM{PjR|OEm=
HUVEC  M3;5cWZ2dmO2aX;uJGF{e2G7 MljlNE42NTJyIN88US=> NWDkOoxlOjRiaB?= NUXtW|RoTE2VTx?= NYThV2g{e3WycILld5NmeyC2aHWgbJlxd3irYT3pcoR2[2WmIHHjZ5VufWyjdHnvckBw\iCKSV[tNe6y M1zyOVIyPTJ|NUW5
 U-373 MG MmrvR5l1d3SxeHnjbZR6KEG|c3H5 Ml;2N{8yOCEQvF2= NIriPZQzPCCq MVjy[YR2[2W|IF\OMe6{NWmwZIXj[YQh[2WubDDu[ZVzd3SxeHnjbZR6 MUGyNFg5QDRzNh?=
MDA-MB-231 M13CZWdzd3e2aDDJcohq[mm2aX;uJGF{e2G7 NIToN5c4OiCq NXewSGtFUUN3MP-8olExOCEQvF2= NUHTfW12OjByN{K2OVI>
SK-BR-3 NVzkVI1tT3Kxd4ToJGlvcGmkaYTpc44hSXO|YYm= MmnhO|IhcA>? M4\tUmlEPTExvK6xNFAh|ryP NHzQcmIzODB5Mk[1Ni=>
PANC-1 MmHuS5Jwf3SqIFnubIljcXSrb36gRZN{[Xl? M37WSFczKGh? MkGwTWM2OO,:nkGwNEDPxE1? MnruNlAxPzJ4NUK=
HPAC NXHS[41JT3Kxd4ToJGlvcGmkaYTpc44hSXO|YYm= MoK3O|IhcA>? NFzRcolKSzVy78{eNVAxKM7:TR?= M4PKUFIxODd{NkWy
U87 MWLHdo94fGhiSX7obYJqfGmxbjDBd5NigQ>? MWC3NkBp NVzXUZFEUUN3ME21OU4yKM7:TR?= MVSyNFA4OjZ3Mh?=
U373  M4Pvcmdzd3e2aDDJcohq[mm2aX;uJGF{e2G7 NUXMeYZEPzJiaB?= MkLzTWM2OD13Mj61JO69VQ>? NYrCWVRxOjByN{K2OVI>

... Click to View More Cell Line Experimental Data

Methods Test Index PMID
Western blot
STAT3 / p-STAT3 / Cyclin D1 / Bcl-2 / Nanog / OCT4 / ALDH1 / CD44; 

PubMed: 26556875     

Western blotting shows S3I-201 treatment decrease Cyclin D1, Bcl2 and self-renewal marker Nanog, OCT4, ALDH1, and CD44 in a dose dependent manner. Data shown are representative of three individual experiments.


PubMed: 28605599     

The expression level of PD-L1 was measured by Western blotting in a head and neck squamous cell carcinoma cell line (Cal 27 and FaDu), with and without S3I-201. β-Actin was used as the internal protein loading control. PD-L1, programmed death 1 ligand; STAT, signal transducers and activators of transcription; p-STAT3, phosphorylated STAT3.

26556875 28605599

PubMed: 26556875     

Immunoflurosece shows S3I-201 reduce nuclear expression of p-STAT3Tyr705 by confocal microscope. 

Oct4 / Twist ; 

PubMed: 27521216     

Suppression of Oct4 and Twist expression was shown in TW01 CD44/CD24 co-overexpressed cells and CSCs after S3I-201 treatment. Scale bars indicate 20 μm.

26556875 27521216
Growth inhibition assay
Cell viability; 

PubMed: 26813676     

The STAT3 inhibitor (S3I-201) decreases cellular proliferation in HTLV-I/ATL-lines. Cells were treated with 0, 12.5, 25, or 50 μM S3I-201 or dimethyl sulfoxide (DMSO) for 72 hours. The average growth curve is representative of the percentage of proliferation between S3I-201 and DMSO-treated cells. Each cell line was treated at least twice for standard deviation. 1185 (-IL2) cells were washed in phosphate-buffered saline and resuspended in media without IL2, followed by treatment with S3I-201 for 72 hours.

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]


Kinase Assay:[1]
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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 Research:[2]
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  • 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.
    (Only for Reference)
Animal Research:[1]
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  • Animal Models: Human breast cancer MDA-MB-231 cells are injected s.c. into the left flank of athymic nu/nu mice.
  • Dosages: ≤5 mg/kg
  • Administration: Administered via i.v.
    (Only for Reference)

Solubility (25°C)

In vitro DMSO 73 mg/mL (199.8 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+corn oil
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 365.36


CAS No. 501919-59-1
Storage powder
in solvent
Synonyms NSC 74859
Smiles CC1=CC=C(C=C1)[S](=O)(=O)OCC(=O)NC2=CC=C(C(O)=O)C(=C2)O

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID