Anti-proliferative effects of the arotinoid Ro 40-8757 on human cancer cell lines in vitro.

A novel arotinoid with a morpholine structure in the polar end group Ro 40-8757 (4-[2-[p-[(E)-2(5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2- naphthyl)propenyl]phenoxy]ethyl]-morpholine) was tested for its anti-proliferative activity against nine human cancer cell lines in vitro. The lines included two estrogen receptor positive breast cancer lines (MCF-7 and ZR-75-1), two estrogen receptor negative breast cancer lines (MDA-MB-231 and BT-20), one cervix carcinoma line (KB-3-1), two lung adenocarcinoma lines (A549 and HLC-1), one large cell lung cancer line (LXFL 529) and two colorectal lines (CXF 243 and CXF 280). Proliferation of all the lines, except the two lung adenocarcinoma lines, was inhibited by lower concentrations of Ro 40-8757 than those of all-trans retinoic acid (RA) or 13-cis RA giving the same level of inhibition. The degree of inhibition of RO 40-8757 was concentration and time dependent. The arotinoid was not cytotoxic and morphological signs by differentiation were not evident in cultures treated with Ro 40-8757 for up to 2 weeks. Because this compound is active on cells such as KB-3-1 that are not inhibited by all-trans RA and because it does not bind to nuclear retinoic acid receptors, it may represent a novel class of anti-proliferative agents.