Controlling Reproduction

RU 486 and Medical Abortion

What is it?

Misfepristone (chemfinder.com) Misoprostol (chemfinder.com)

RU 486 is an orally administered drug that can be used to chemically terminate a pregnancy. RU 486 is often called an abortifacient, meaning simply that it is a chemical that induces abortion of a developing embryo. RU 486 is synonymous with mifepristone and is part of a regime that is referred to as a medical abortion. A medical abortion consists of two processes:

1) Termination of the pregnancy

2) Expulsion of the pregnancy

The procedure itself is a regime of two pills: mifepristone and misoprostol. Mifepristone blocks the production of hormones needed to sustain pregnancy, and Misoprostol induces uterine contractions to expel the products of conception (Chesler, 2001). Misoprostol was originally approved to treat ulcers and did not need additional FDA approval for use in medical abortions. The FDA approved RU 486 in 2000 (Hatcher et al. 2003).

Misfepristone (RU 486)

RU 486 causes many cellular changes that ultimately result in the termination of embryo development. RU 486 is progesterone antagonist, meaning it blocks progesterone receptors and inhibits the transcription of progesterone dependent genes (Hatcher et al. 2003). RU 486 also antagonizes glucocorticoid receptors resulting in the down regulation of glucocorticoid dependent genes (Rodriguez and Palou, 2004). These two antagonizing functions detach the uterine lining, effectively terminating the pregnancy (Fielding and Schaff, 2004). Misfepristone was patented in 1982 by a French pharmaceutical company that later transferred the patent to the U.S. Population Council in 1994 (Population Council, 2001).

RU 486, since FDA approval, has been studied in a variety of biological capacities and looks promising not only for medical abortion but for processes unrelated to reproduction. RU 486 has been used an anti-tumor drug. Research has shown that pregnancy relies on the down regulation of Monocyte Chemotactic Protein-3 (MCP3). MCP3 is a pro-inflammatory, CC chemokine and a Th1 effecter, which is capable of eliciting significant anti-tumoral immune responses. Essentially, MCP3 is linked to suppressing tumors. RU 486 administration in mice showed MCP3 amplification, which would terminate a pregnancy and stop tumor growth (Nautiyal et al. 2004). One issue facing breast cancer treatment is resistance to anti-estrogen therapy. Studies using RU 486’s anti-progesterone qualities, when coupled with anti-estrogen therapy, combats anti-estrogen resistance in breast cancer cells (Gaddy et al. 2004)

RU 486 has also been implicated as being useful for obesity prevention. When cells were treated with a combination of RU 486 and progesterone, there was a direct effect on the growth of fat cells (Rodriguez and Palou, 2004). One possible mechanism for affecting fat cell growth is that RU 486 stimulates the production of uncoupling proteins (Rogriquez and Palou, 2004) In addition, RU 486 is a known treatment option for patients suffering from Cushing’s syndrome. Cushing’s syndrome is marked by increased production of cortisol by the adrenal gland; RU 486 helps to lessen the damage that cortisol causes to target tissues (Lader, 1991).

Questions or Comments: Email Dr. Verna Case

Davidson College Biology Department

Davidson College

This web page was produced as an assignment for an undergraduate course at Davidson College.