AM580 (Synonyms: CD336, NSC 608001, Ro 406055)

Kinase experiment:

Approximately 1×106 NB4, HL-60, and APL fresh leukemic cells or CML neutrophils are harvested, pelletted by centrifugation at 400 g for 10 minutes, washed once with 0.9% NaCl, and centrifuged again. The washed cell pellet is resuspended in homogenization buffer (1 mM MgCl2, 1 mM CaCl2, 20 mM ZnCl2, 0.1 mM NaCl, 0.1% [vol/vol] Triton X-100, 50 mM Tris/HCl, pH 7.4) and disrupted by vigorous pipetting. The homogenate is used for the LAP assay, which is performed with p-nitrophenol phosphate as substrate according to the instructions of the manufacturer. LAP activity is normalized for the content of protein in the sample. Proteins are measured according to the Bradford method using BSA fraction V as a standard. One unit of LAP activity is defined as the amount of enzyme capable of transforming 1 nmol of substrate in 1 minute at 25°C. Enzyme assays are performed in conditions of linearity relative to the substrate and to the concentration of proteins.

Cell experiment:

MCF-10A (2×104) control cells or overexpressing RARγ are seeded in triplicates in 6-well culture dishes. After 24 hrs, cells are washed with PBS, incubated in 2 mL of DMEM-F12 culture medium, detached and counted every 24 hrs. Statistical significance is determined by t-test. pRB and p27 expression is tested by immunofluorescence analysis of control MCF-10A monolayers and monolayers stably transfected with pSG5-RARγ expression vector, using the same antibodies described for the IHC analysis.

Animal experiment:

Four months old uniparous (1 pregnancy/lactation cycle) MMTV-neu and 6 weeks old nulliparous MMTV-wnt1 female mice (50 mice/group) are treated with the RARα agonist AM580 (0.3 mg/kg body weight per mouse per day) in the diet (Purina 5053) by adding 1.5 mg AM580 per kg of Purina 5053 diet. Mice that develop tumors within the first month of treatment are removed from the study. Mice are palpated twice a week and tumor appearance is recorded. Once palpable, the size of the tumors is measured weekly. Tumor-free survival is calculated from Kaplan-Meier curves and statistical significance is determined by the Log-rank test for the survival studies and t-test for the tumor growth studies. Metastasis is evaluated by removing the lungs of all the anesthetized mice, selecting randomLy 20 mice per group and inspecting the lung surface for lesions using a stereoscope.

References:

[1]. Gianní M, et al. AM580, a stable benzoic derivative of retinoic acid, has powerful and selective cyto-differentiating effects on acute promyelocytic leukemia cells. Blood. 1996 Feb 15;87(4):1520-31.
[2]. Lu Y, et al. Mechanism of inhibition of MMTV-neu and MMTV-wnt1 induced mammary oncogenesis by RARalpha agonist AM580. Oncogene. 2010 Jun 24;29(25):3665-76.
[3]. Bosch A, et al. Reversal by RARα agonist Am580 of c-Myc-induced imbalance in RARα/RARγ expression during MMTV-Myc tumorigenesis. Breast Cancer Res. 2012 Aug 24;14(4):R121.