A and B forms of the androgen receptor are expressed in a variety of human tissues

Human genital skin fibroblasts contain both the full-length 110 K androgen receptor protein (AR-B, apparent M(r) approximate to 110000) and an 87 K N-terminally truncated AR isoform (AR-A, apparent M(r) approximate to 87000). These two AR species are structurally analogous to the A- and B-isoforms of the progesterone receptor (PR). We examined the distribution pattern of human AR isoforms in a variety of fetal and adult tissues by Western blot analysis. Relative levels of immunoreactive AR proteins in high salt tissue extracts were estimated by densitometry in comparison to a standard normal genital skin fibroblast preparation. High AR levels (AR-A + AR-B = 0.8-7.7) were present in male and female reproductive tissues from mid-trimester fetuses, including penis, prostate, testis, epididymis, scrotal skin, labial skin, uterus/cervix, and ovary. AR-A and AR-B (0.08-0.9) also were found in 14 non-genital fetal tissues (bladder, fat, lung, great vessel, trachea, muscle, scalp skin, kidney, thyroid, intestine, thymus, ureter, stomach and rectum). AR-A accounted for 4-26% of the AR protein detected in these tissues. Ten other fetal tissues had low levels of AR-B (0.02-0.3) and little or no delectable AR-A. AR-B also was the predominant or only immunoreactive AR species found in 17 adult human tissues. AR levels in adult reproductive tissues (prostate, endometrium, ovary, uterus, fallopian tube, testis: seminal vesicle, myometrium, and ejaculatory duct) ranged from 0.1 to 2.2. Immunoreactive AR (0.4-0.8) also was present in specimens of prostate carcinoma, endometrial carcinoma, thyroid carcinoma and kidney. Lower levels of AR (0.03-0.1) were detected in adult breast, colon, lung and adrenal gland specimens. This study demonstrates that immunoreactive AR protein is present in a wide variety of human fetal and adult tissues and that two AR isoforms are expressed in many tissues.