Expression of Co-factors (SMRT and Trip-1) for Retinoic Acid Receptors in Human Neuroectodermal Cell Lines

Abstract

Retinoic acid (RA) induces growth inhibition, differentiation or cell death in many human neuroblastoma cell lines. Recently, the transactivation activity of nuclear retinoids receptors has been shown to be modulated through physical association with other proteins that act as co-activators or as co-repressors. We investigated the expression of the co-repressor (SMRT) and co-activator (Trip 1) for retinoid and thyroid-hormone receptors in several neuroectodermal tumour cell lines, and its modulation by all-trans-retinoic acid, as well as by synthetic agonists, for RARα, RARβ, RARγ and RXR. We demonstrate that (i) SMRT and Trip-1 mRNAs are expressed in many human neuroblastoma and melanoma cell lines in basal conditions, (ii) SMRT mRNA expression in human neuroblastoma cell line SK-N-BE(2) increases after 48 hours of incubation with 1 μM RA and RARs specific agonists, (iii) Trip-1 mRNA in the same cell line does not change during incubation with RA or selective synthetic agonists for RARs and RXR.