Recombinant Cell-Based Bioluminescence Assay for Androgen Bioactivity Determination in Clinical Samples

Abstract

Androgens regulate several physiologic processes, such as normal prostate development and maintenance of male sexual function in adult life, and they are also involved in pathologic conditions, including prostate cancer, prepubertal gynecomastia, and premature pubarche. Androgens enter the target cell and bind to androgen receptor (AR), a ligand-dependent transcription factor in the nuclear receptor superfamily comprising receptors for vitamin D3 and thyroid and steroid hormones (1)(2). After binding of the hormone, AR enters the nucleus and binds to the regulatory region of the target gene as a homodimer. Recent findings suggest that some environmental chemicals disrupt the endocrine system and cause adverse effects such as cancers and sexual abnormalities in humans and wildlife (3). These endocrine-disrupting compounds include several xenoestrogens, androgens, and antiandrogens, which present a variety of chemical structures and mechanisms of action (4)(5). Conventional detection methods for androgenic and antiandrogenic compounds cannot evaluate hormonal bioactivity, which is important in a wide range of clinical conditions, and no alternative direct and simple methods for measurement of plasma androgen bioactivity are available. In addition, the increased use of androgenic substances as therapeutic drugs and their abuse to enhance athletic performance require sensitive and rapid screening tests. The very low amounts of single analytes in anabolic cocktails and nutritional supplements are difficult to detect with standard techniques such as gas chromatography–mass spectrometry. Thus, bioassays that reveal the overall androgen bioactivity of complex mixtures would be more appropriate tools with great implications in antidoping analysis (6)(7)(8). We developed and validated a yeast-based bioassay to measure androgen bioactivity in clinical samples, including human serum, for the detection of androgen-like and antiandrogenic compounds (9). The bioassay is based on recombinant Saccharomyces cerevisiae BMA64-1A strain genetically engineered with the introduction of 2 plasmids: an …