Home Endocrinology & Hormones Aromatase inhibitor - Autophagy activator Letrozole For research use only.

Letrozole

Synonyms: CGS 20267

Letrozole is a third generation inhibitor of aromatase with IC50 of 0.07-20 nM in cell-free assays.It has no effect on the plasma levels of 17α-OH progesterone, thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), or androstenedione and does not affect normal urine electrolyte excretion or thyroid function in clinical studies. Letrozole induces autophagy.

Letrozole Chemical Structure

Letrozole Chemical Structure

CAS: 112809-51-5

Selleck's Letrozole has been cited by 34 publications

Purity & Quality Control

Batch: Purity: 99.99%
99.99

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Cell Data

Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID
JEG3 Function assay Inhibition of aromatase activity in human JEG3 cells, IC50=0.00089μM 18590272
JEG3 Function assay Inhibition of aromatase in human JEG3 cells by scintillation spectrometry, IC50=0.00089μM 20148564
MDA-MB-435 Growth inhibition assay 48 hrs Growth inhibition of human MDA-MB-435 cells after 48 hrs by sulforhodamine B assay, GI50=0.067μM 20950898
IGROV1 Growth inhibition assay 48 hrs Growth inhibition of human IGROV1 cells after 48 hrs by sulforhodamine B assay, GI50=0.095μM 20950898
MDA-MB-231 Growth inhibition assay 48 hrs Growth inhibition of human MDA-MB-231cells after 48 hrs by sulforhodamine B assay, GI50=0.15μM 20950898
T47D Growth inhibition assay 48 hrs Growth inhibition of human T47D cells after 48 hrs by sulforhodamine B assay, GI50=0.44μM 20950898
MCF7 Growth inhibition assay 48 hrs Growth inhibition of human MCF7 cells after 48 hrs by sulforhodamine B assay, GI50=0.7μM 20950898
OVCAR4 Growth inhibition assay 48 hrs Growth inhibition of human OVCAR4 cells after 48 hrs by sulforhodamine B assay, GI50=0.88μM 20950898
BT549 Growth inhibition assay 48 hrs Growth inhibition of human BT549 cells after 48 hrs by sulforhodamine B assay, GI50=0.89μM 20950898
SKOV3 Growth inhibition assay 48 hrs Growth inhibition of human SKOV3 cells after 48 hrs by sulforhodamine B assay, GI50=1.09μM 20950898
NCI/ADR-RES Growth inhibition assay 48 hrs Growth inhibition of human NCI/ADR-RES cells after 48 hrs by sulforhodamine B assay, GI50=1.16μM 20950898
MDA-N Growth inhibition assay 48 hrs Growth inhibition of human MDA-N cells after 48 hrs by sulforhodamine B assay, GI50=1.61μM 20950898
OVCAR5 Growth inhibition assay 48 hrs Growth inhibition of human OVCAR5 cells after 48 hrs by sulforhodamine B assay, GI50=1.62μM 20950898
Hs 578T Growth inhibition assay 48 hrs Growth inhibition of human Hs 578T cells after 48 hrs by sulforhodamine B assay, GI50=2.17μM 20950898
OVCAR8 Growth inhibition assay 48 hrs Growth inhibition of human OVCAR8 cells after 48 hrs by sulforhodamine B assay, GI50=4.5μM 20950898
OVCAR3 Growth inhibition assay 48 hrs Growth inhibition of human OVCAR3 cells after 48 hrs by sulforhodamine B assay, GI50=5.87μM 20950898
MCF7a Cytotoxicity assay 10 days Cytotoxicity against human MCF7a cells expressing Tet-off-3betaHSD1-Arom assessed as inhibition of TST-stimulated cell proliferation measured after 10 days, EC50=0.000004μM 22951074
V79MZh Function assay Inhibition of human CYP11B2 expressed in hamster V79MZh cells using [1,2-3H]-11-deoxy-corticosterone as substrate, IC50=1.42μM 23281812
V79MZh Function assay Inhibition of human CYP11B1 expressed in hamster V79MZh cells using [1,2-3H]-11-deoxy-corticosterone as substrate, IC50=2.62μM 23281812
H295R Function assay 5 uM 24 hrs Inhibition of CYP19 in human H295R cells using [1beta-3H(N)]-androst-4-ene-3,17-dione at 5 uM after 24 hrs by tritiated water release assay 24025069
MCF7 Cytotoxicity assay 72 hrs Cytotoxicity against estrogen-dependent human MCF7 cells after 72 hrs by MTT assay, IC50=0.007μM 24345481
MCF7 Cytotoxicity assay 24 to 96 hrs Cytotoxicity against human MCF7 cells after 24 to 96 hrs, IC50=0.02μM 24345481
JEG-3 Function assay Inhibition of aromatase (unknown origin) expressed in JEG-3 cells, IC50=0.00089μM 25992880
insect cells Function assay 30 mins Inhibition of recombinant human CYP19 expressed in baculovirus infected insect cells using MFC as substrate measured after 30 mins by fluorometric analysis, IC50=0.0053μM 27647367
T47D Function assay 24 hrs Inhibition of aromatase activity in human T47D cells after 24 hrs, IC50=29.5μM 27770735
T47D Function assay 24 hrs Inhibition of aromatase activity in human T47D cells after 24 hrs, IC50=29.5μM 28427017
MCF7 Cytotoxicity assay 48 hrs Cytotoxicity against human MCF7 cells after 48 hrs by MTT assay, IC50=4.73μM 29202405
MCF7 Growth inhibition assay 72 hrs Growth inhibition of human MCF7 cells incubated for 72 hrs by cell counting based method, GI50=4.1μM 30822713
MDA-MB-231 Growth inhibition assay 72 hrs Growth inhibition of human MDA-MB-231 cells incubated for 72 hrs by cell counting based method, GI50=10μM 30822713
insect cells Function assay Inhibition of recombinant human aromatase expressed in baculovirus infected insect cells using O-benzyl fluorescein benzyl ester as substrate in presence of NADPH generating system by fluorescence based analysis, IC50=0.0019μM 31416738
MCF-7aro Function assay 1 hr Inhibition of aromatase in human MCF-7aro cells using [1beta-3H] androstenedione as substrate incubated for 1 hr by liquid scintillation counting method, IC50=0.0019μM 31732252
insect cells Function assay 30 mins Inhibition of human recombinant aromatase expressed in baculovirus infected insect cells using O-benzylfluorescein benzyl ester as substrate after 30 mins, IC50=0.0011μM ChEMBL
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Biological Activity

Description Letrozole is a third generation inhibitor of aromatase with IC50 of 0.07-20 nM in cell-free assays.It has no effect on the plasma levels of 17α-OH progesterone, thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), or androstenedione and does not affect normal urine electrolyte excretion or thyroid function in clinical studies. Letrozole induces autophagy.
Targets
Aromatase [1]
(Cell-free assay)
0.07 nM-20 nM
In vitro
In vitro

Letrozole potently inhibits aromatase derived from a variety of different sources including human placental microsomes, particulate fractions of human breast cancer, rat ovarian microsomes, MCF-7 cells transfected with aromatase (MCF-7Ca), JEG-3 human choriocarcinoma cells , CHO cells, hamster ovarian tissue, and particulate fractions of human breast cancer with IC50 of 11, 2, 7, 0.07, 0.07, 1.4, 20 and 0.8 nM. In the non-cellular systems, the IC50 of letrozole is calculated to be 1-13 nM. [1] Letrozole maximally inhibits estradiol production in vitro in LH-stimulated hamster ovarian tissue at 0.1 μM with an IC50 of 0.02 μM and does not significantly affect progesterone production up to 350 μM. In ACTH-stimulated rat adrenal tissue in vitro, aldosterone production is inhibited by with an IC50 of 210 μM. [2] Letrozole inhibits growth of the MCF-7 epithelial breast cancer cells in a dose-dependent way with IC50 of 1 nM. Inhibition can be observesed even at the very low concentrations tested (0.1 nM). Treatment of normal MCF-12A epithelial cells with letrozole did not affect their growth even when high letrozole concentrations (100 nM) or prolonged culture times. Concurrent administration of 17-β-estradiol with letrozole (10 nM) decreased the stimulatory effect of the enzymatic activity of MMP-2 and - 9 released by estradiol. [3]
Kinase Assay Human placental aromatase activity
The assay is performed in a total volume of 1 mL at 37 ℃. Unless otherwise noted, the incubation mixture contains 11 nM [4- 14C] androstene-3, 17-dione ([4- 14C]A), 24 mM NADPH (tetrasodium salt Type III), the appropriate concentrations of the desired inhibitor, and 120 μg of microsomal protein. The (4- 14C)A is added as a solution in 1.7% ethanol in 0.05 M potassium phosphate buffer (pH 7.4), so that the final concentration of ethanol does not exceed 0.02% (v/v). The reaction is started by the addition of enzyme and stopped after 20 min by the addition of 7 vol of ethyl acetate. The mixture is agitated on a vortex mixer and centrifuged at 600 g for 5 min. The aqueous phase is re-extracted with 7 vol of ethyl acetate, and the combined extracts are evaporated to dryness using an Evapo-Mix. Over 99% of the radio- active of [4- 14C] added is recovered using this extraction system. The residue obtained is dissolved in 150 μL acetone, and 100 μL aliquots are chromatographed for 65 min on thin-layer plates precoated with silica gel 60 using ethyl: acetate: isooctane (140:60, v/v; system A) or toluene: chloroform: methanol (70:140:20; system B). The radioactive zones of the plate are located with a Berthold LB 2760 thin-layer scanner. The radioactive estradiol (E2) and estrone (E1) neaks are identified by comparison with authentic standards. The corresponding bonding band of silica gel is transferred to vials containing 10 mL of scintillation fluid, and counted with a 6880 Liquid Scintillation system.
Cell Research Cell lines Human breast cancer cells MCF-7
Concentrations ~100 nM
Incubation Time 1 days
Method

Cells are seeded in duplicate at 5,000 to 10,000 cells per well in 24-well plates. The day after plating, different concentrations of Letrozole are added. At the end of incubation, cells are trypsinizated and placed in Isotone solution and counted immediately using a Coulter particle-counter.
In Vivo
In vivo

Letrozole inhibits aromatase in vivo with ED50 of 1-3 μg/kg p.o.. [2] Letrozole displays anti-endocrine effects. Letrozole inhibits androstenedione-induced uterine hypertrophy in immature rats with ED50 of 1-3 μg/kg. In the adult female rat, Letrozole (0.3-1 mg/kg daily p.o., 14 days) completely interrupts ovarian cyclicity and reduces uterine weight and serum estradiol (E2) concentrations to a similar extent to that seen after ovariectomy. [1] Letrozole induces dose-dependent regression of estrogen-dependent, 9,10-dimethylbenz-a-anthracene-induced mammary tumors in adult female rats. The ED50 for Letrozole is determined to be 10 - 30 µg/kg/day, with complete inhibition at a daily dose of 10 µg/day. [4] Letrozole produces dose-dependent inhibition of tumor growth of MCF-7 cells transfected with human aromatase gene (MCF-7Ca) implanted athymic nude mice, with complete inhibition at 20 mg/kg per day p.o.. [5]
Animal Research Animal Models Human breast carcinoma xenografts MCF-7 with human aromatase gene (MCF-7Ca)
Dosages 20 mg/kg/day
Administration orally administered by gavage once every 2 days
NCT Number Recruitment Conditions Sponsor/Collaborators Start Date Phases
NCT05872204 Recruiting Low Grade Serous Ovarian Carcinoma|Adult Type Granulosa Cell Tumor Universitaire Ziekenhuizen KU Leuven|Kom Op Tegen Kanker|Eli Lilly and Company|European Network of Gynaecological Oncological Trial Groups (ENGOT) November 30 2023 Phase 2

Chemical lnformation & Solubility

Molecular Weight 285.3 Formula

C17H11N5
CAS No. 112809-51-5 SDF Download Letrozole SDF
Smiles C1=CC(=CC=C1C#N)C(C2=CC=C(C=C2)C#N)N3C=NC=N3
Storage (From the date of receipt)

In vitro
Batch:

DMSO : 57 mg/mL ( (199.78 mM)； Moisture-absorbing DMSO reduces solubility. Please use fresh DMSO.)

Water : Insoluble

Ethanol : Insoluble


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