Enhancement of HL-60 Differentiation by a New Class of Retinoids with Selective Activity on Retinoid X Receptor

doi:10.1074/jbc.270.51.30765

Enhancement of HL-60 Differentiation by a New Class of Retinoids with Selective Activity on Retinoid X Receptor (*)

From the From Preclinical Research, Department of Dermatology, F. Hoffmann-LaRoche, CH-4002 Basel, Switzerland

^§ To whom correspondence should be addressed:
PRPD, 60/409, F. Hoffmann-La Roche Ltd., CH-4002 Basel, Switzerland.
Tel.: 41-61-688-5878; Fax: 41-61-688-8616.

↵^¶ Present address: Bayer AG, 42096 Wuppertal, Germany.
↵** Present address: Pfizer Central Research, Groton, CT 06340.

Abstract

Cellular responsiveness to retinoic acid and its metabolites is conferred through two distinct families of receptors: the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). Herein, we report on the identification and characterization of several conformationally restricted retinoids, which selectively bind and activate RX receptors. Under the influence of retinoids, HL-60 myelocytic leukemia cells differentiate into granulocytes. This effect is mediated by RARα, as has been demonstrated through the use of a selective RARα antagonist (Apfel, C., Bauer, F., Crettaz, M., Forni, L., Kamber, M., Kaufmann, F., LeMotte, P., Pirson, W., and Klaus, M.(1992) Proc. Natl. Acad. Sci. U. S. A. 89, 7129-7133). Here, we show that conformationally restricted RXR-specific retinoids, at doses that are per se inactive, are able to potentiate by up to one order of magnitude the pro-differentiating effects of all-trans retinoic acid and an RARα-selective synthetic retinoid. We also present evidence that these RXR-selective ligands are able to bind to a DNA RXR•RAR heterodimer complex. This finding demonstrates that agonists for RARs and RXRs can synergistically promote HL-60 differentiation, which could be mediated through a heterodimer of these receptors.

Footnotes

↵* The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

RXR

retinoid X receptor

RAR

retinoic acid receptor

t-RA

all-trans retinoic acid

9-cis RA

9-cis retinoic acid

RARα and RXRα

retinoic acid receptors

RARE

RAR response element

RXRE

RXR response element

CRBP II

cytoplasmic retinol binding protein II

SeAP

secreted alkaline phosphatase

TK

thymidine kinase

luc

luciferase

CDTA

1,2-diaminocyclohexan-N,N,N′,N′-tetraacetic acid

NBT

nitro blue tetrazolium

FCS

fetal calf serum.
- Received June 5, 1995.
- Revision received October 11, 1995.