Isolation and identification of 4-hydroxy- and 4-oxoretinoic acid. In vitro metabolites of all-trans-retinoic acid in hamster trachea and liver

Abstract

Incubation of [3H]retinoic acid in the presence of hamster liver 10000g supernatant produces several metabolites that are more polar than the parent compound. Two of these metabolites are identical with synthetic all-trans-4-hydroxyretinoic acid and all-trans-4-oxoretinoic acid both in ultraviolet absorption and mass spectral characteristics and in migration rates on two different reverse-phase high-pressure liquid chromatographic systems. The metabolites produced in a cell-free liver incubation reaction also migrate on a high-pressure liquid chromatography column together with metabolites isolated from a tracheal organ culture system. Both the metabolites and the synthetic standards show less biological activity than the parent all-trans-retinoic acid in a tracheal organ culture assay.

All-trans-retinoic acid metabolites significantly inhibit the proliferation of MCF-7 human breast cancer cells in vitro

“…However, their activity in our study was higher than would have been expected from previous reports where these catabolites were found to be less potent than ATRA in (a) the inhibition of growth and the inhibition of hormone isobutylmethylxanthine-inducible tyrosinase activity of Cloudman S-91 mouse melanoma cells (Lotan et al, 1980;Reynolds et al, 1993); (b) the induction of differentiation of F9 mouse teratocarcinoma cells as measured by ELISA for laminin (Williams et al, 1987); and (c) the induction of differentiation and inhibition of proliferation of BA-HAN-IC rat rhabdomyosarcoma cells (Ramp et al, 1994). In contrast, both catabolites have been reported to be virtually inactive (Frolik et al, 1979;Silva et al, 1987). In our MCF-7 model system, the catabolites 4-oxo-ATRA and 5,6-epoxy-ATRA were as potent as ATRA at concentrations of 10-8 M and 10-7 M, but were twofold less potent at 10-6 M. It is clear that a complex phenomenon is occurring for which there is no obvious explanation.…”

“…ATRA metabolism has been studied in a variety of tissues and a number of metabolites have been identified ( Figure 1). One important catabolic pathway for ATRA is initiated by hydroxylation at the four position of the P-ionone ring of ATRA to yield 4-hydroxy-ATRA (Frolik et al, 1979;Roberts et al, 1980). This step is catalysed by a cytochrome P450-dependent ATRA 4-hydroxylase (Roberts et al, 1980;White et al, 1996).…”

The antiproliferative activity of all-trans-retinoic acid catabolites and isomers is differentially modulated by liarozole-fumarate in MCF-7 human breast cancer cells

“…ATRA is rapidly metabolized in a catabolic pathway that includes the 4-hydroxylation of the f-ionone ring to yield 4-hydroxy-ATRA (Frolik et al, 1979, Roberts et al, 1980). This step is catalysed by a cytochrome P450-dependent ATRA 4-hydroxylase (Roberts et al, 1980;White et al, 1996).…”

Induction of the oxidative catabolism of retinoic acid in MCF-7 cells

“…Probably because of its potent physiological activity, retinoic acid is subject to various catabolic transformations (Frolik et al, 1979;Sietsema and De Luca, 1982;Kraft et al, 1991). A primary route by which retinoic acid is catabolized consists of a cytochrome P450-dependent hydroxylation to form 4-hydroxy-RA, which is further oxidized to 4-keto-RA and more polar metabolites .…”

“…Recently all-trans-RA catabolism was further demonstrated in MCF-7 breast cancer cells and rat Dunning R3327G prostate tumour homogenates (Krekels et al, 1995). In vivo catabolism of all-trans-RA has been extensively documented in rodents (Hanni et al, 1976;Hanni and Bigler, 1977;Frolik et al, 1980 (Dijkman et al, 1994;Smets et al, 1995) and in prostate cancer patients (Mahler et al, 1993 (Muindi et al, 1992), suggesting that all-trans-RA induces its own catabolism.…”