NSC23005 targets p18INK4C (also known as INK4C or p18), a member of the INK4 family of cyclin-dependent kinase inhibitors that negatively regulates the cell cycle. By inhibiting p18, it relieves cell cycle blockade, thereby promoting the proliferation and expansion of hematopoietic stem cells (HSCs) without causing significant cytotoxicity or promoting leukemic cell growth.

NSC23005 sodium is a novel and potent p18 inhibitor with ED50 of 5.21 nM in promoting Hematopoietic stem cells (HSCs) expansion in both murine and human models. Hematopoietic stem cells have emerged as promising therapeutic cell sources for high-risk hematological malignancies and immune disorders. However, their clinical use is limited by the inability to expand these cells ex vivo. Therefore, there is an urgent need to identify specific targets and effective probes that can expand HSCs. NSC23005 sodium represents novel chemical agents for murine and human HSCs ex vivo expansion and also can be used as valuable chemical probes for further HSC biology research towards promising utility for therapeutic purposes. NSC23005 sodium is a novel class of INK4C (p18INK4C or p18) small molecule inhibitor (p18SMIs), which is initially found by in silico 3D screening. NSC23005 sodium shows the most potent bioactivity in hematopoietic stem cells (HSCs) expansion (ED50=5.21 nM). Notably, NSC23005 sodium does not show significant cytotoxicity toward 32D cells or HSCs, nor does it augment leukemia cell proliferation. NSC23005 sodium (ED50=5.21 nM), shows no activity in promoting the proliferation of leukemia cells.
Kinase Assay: rior to culture, cKit-enriched BM cells (1 × 106/mL) were labeled with 5- (and 6-) carboxy-fluorescein diacetatesuccinimidylester (CFSE) dye (3 μM, Molecular Probes) in PBS supplemented with 0.1% bovine serum albumin. Labeling was performed in the dark at 37 °C for 10 min. Labeling was stopped by the addition of 5 volumes of ice cold PBS. 4 days after culture with cytokine plus compound, labeled cells were harvested and stained with the antibody cocktail for lineage markers, Sca-1, CD48, and CD150. During cell division, CFSE is distributed equally between daughter cells so that the generation of cells could be reflected by the content of CFSE and measured by the intensity of fluorescence. The CyAnsystem (DakoCytomation) was used for data acquisition. The data was analyzed using cells/Proliferation module of FlowJo software (Treestar, Inc.), which would fit a curve of the input data, automatically generate peaks standing for subpopulations with different fluorescence intensity and calculate the percentage of each peak and divided statistics results.
Cell Assay: c-Kit enriched bone marrow (BM) cells are cultured for 5 days with cytokine combination plus NSC23005 sodium or DMSO. As positive controls, primary uncultured bone marrow cells are treated by ultraviolet radiation (UV) for 10 minutes prior to the staining process for apoptosis analysis. Apoptosis and cell death are measured by AnnexinV and DAPI staining in the Annexin V-FITC Apoptosis Detection Kit. Apoptosis is measured on an FACS analyzer. The data is analyzed using FlowJo software.
NSC23005 is a potent p18 inhibitor that promotes hematopoietic stem cell (HSC) expansion with an ED50 of 5.21 nM. It represents a novel class of p18 small molecule inhibitors (p18SMIs) initially discovered through in silico 3D screening. Notably, NSC23005 does not show significant cytotoxicity toward 32D cells or HSCs, nor does it augment leukemia cell proliferation, demonstrating selectivity for HSC expansion over malignant cell growth.

Mice (6–8 weeks old) were purchased from Jackson laboratory (Bar Harbor, ME) and housed in specific pathogen-free rooms within the animal-care facilities of the University of Pittsburgh Cancer Institute. All procedures of the mouse work were approved by the Institutional Animal Care and Use Committee at the University of Pittsburgh. HSCs expansion medium consists of BIT9500 (Stem Cell Technologies) supplemented with 50 ng/mL recombinant mouse (rm) SCF, 20 ng/mL FMS-like tyrosine kinase 3 ligand (Flt3L) and 10 ng/mL thrombopoietin (Tpo) (all from PeproTech, Inc.). p18SMI compounds were added where indicated. Bone marrow cells were harvested from C57BL/6 mice and made into a single-cell suspension. After immunomagnetic c-Kit enrichment (cKit-conjugated microbeads [MiltenyiBiotec, Bergisch-Gladbach]), cells were washed and resuspended in HSCs expansion medium. After culture, total nucleated cell counts were obtained, and a fraction of mononuclear cells (MNCs) or whole bone marrow cells were stained for flow cytometry analysis. Frequency of each cell population was determined by independently analyzing more than 5 × 105 cells per sample in triplicate.

Cell-free assays for NSC23005 typically involve binding or inhibition studies using purified p18 protein. As a small molecule inhibitor identified through in silico screening, its direct interaction with p18 can be assessed using surface plasmon resonance (SPR) or isothermal titration calorimetry (ITC) to measure binding affinity. Competitive binding assays with fluorescent probes can also be employed to determine inhibition constants.

Cellular assays for NSC23005 are performed using cKit-enriched bone marrow cells or purified hematopoietic stem cells. Cells are labeled with CFSE dye and cultured with cytokines plus varying concentrations of the compound for 4 days. HSC expansion is assessed by flow cytometry using lineage markers, Sca-1, CD48, and CD150. ED50 values are determined from dose-response curves, and cytotoxicity is assessed in parallel using 32D cells or other control cell lines.

Mice (6–8 weeks old)

NSC23005 is a small molecule with molecular weight of 283.34 g/mol and molecular formula C13H17NO4S. It is soluble in DMSO (45 mg/mL). As a research compound, its pharmacokinetic properties have not been extensively characterized in the literature. Its primary application is for ex vivo HSC expansion, where it is used directly in cell culture media rather than being administered systemically.

Toxicity data for NSC23005 indicate that it does not show significant cytotoxicity toward 32D cells or HSCs at concentrations that promote HSC expansion. Importantly, it does not augment leukemia cell proliferation, suggesting a favorable safety profile with respect to malignant transformation. Standard toxicological assessments for in vivo applications would be required for therapeutic development.

Sci Rep.2015 Dec 18;5:18115.

NSC23005 (molecular formula C13H17NO4S, MW 283.34) is also known as p18SMI-40 and NSC-23005. It is a novel class of INK4C (p18INK4C) small molecule inhibitor discovered through in silico 3D screening. It effectively promotes HSC expansion with an ED50 of 5.21 nM and represents a valuable chemical probe for HSC biology research. The compound is intended for research use only and is not approved for therapeutic use.

C13H17NO4S

283.34

283.088

6314-70-1

1796596-46-7 (sodium);6314-70-1 (free acid);

229357

Typically exists as solid at room temperature

1.36g/cm3

473.4ºC at 760 mmHg

240.1ºC

1.599

3.467

2

5

4

19

401

0

S(C1C([H])=C([H])C(C(=O)O[H])=C([H])C=1[H])(N([H])C1([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C1([H])[H])(=O)=O

XGOXPTXOQXHIDL-UHFFFAOYSA-N

InChI=1S/C13H17NO4S/c15-13(16)10-6-8-12(9-7-10)19(17,18)14-11-4-2-1-3-5-11/h6-9,11,14H,1-5H2,(H,15,16)

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)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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