ID#

763

Location:

Exhibit Hall

Time of Presentation:

March 11, 2003 - 9:30 a.m.

Category (Subcategory):

In Vitro/Alternative Animal Models, (Endocrine System), (Nuclear and Cytosolic Receptors)

ICCVAM/NICEATM Expert Panel Recommendations for the Standardization and Validation of In Vitro Estrogen Receptor (ER) and Androgen Receptor (AR) Binding Assays
R.R. Tice^1,2; G. Daston³; T. Brown⁴; B.S. Shane^1,2; C.J. Inhof^1,2;
E. Zeiger⁵; W.S. Stokes²
1. ILS, Inc., RTP, NC, USA;
2. NICEATM, NIEHS, RTP, NC, USA;
3. Procter and Gamble, Cincinnati, OH, USA;
4. Johns Hopkins University, Baltimore, MD, USA;
5. Errol Zeiger Consulting, Chapel Hill, NC, USA;

A number of published studies indicate that a variety of natural and anthropogenic substances can interact with the endocrine system. As a result, legislation was enacted requiring the U.S. EPA to develop a screening and testing program to identify substances with endocrine disrupting activity. Within the Tier 1 battery of screening test methods, in vitro ligand binding assays are proposed to identify substances that might interact with the ER or AR. The in vitro results would be considered with data from other Tier 1 assays in a weight-of-evidence evaluation of the need for testing in the more definitive Tier 2 in vivo assays. A comprehensive literature review indicated no adequately validated in vitro ER or AR binding assays. After considering the available data, an ICCVAM/NICEATM-sponsored Expert Panel developed recommendations for future standardization and validation efforts. For both types of binding assays, the Panel recommended recombinant human receptors and high-throughput procedures for validation; however, patent issues with the human AR may make it necessary to use a recombinant receptor derived from a non-human primate. For ER binding assays, the Panel recommended the use of intact human ERa or b proteins or the equivalent proteins from the rat. When screening for ecological effects, recombinant receptors from wildlife should be evaluated. Recommendations were also provided for minimum procedural standards and substances for validation studies. These recommendations should facilitate standardization and validation of protocols for ER and AR binding assays. Supported by NIEHS Contract N01-ES-85424.