RESUMO
Soluble ErbB (sErbB) growth factor receptors are being investigated as cancer biomarkers. Gonadotropic and steroid hormones have been shown to modulate the expression of ERBB family members in vivo. Accordingly, the range of sErbB1 values and their relationship to gonadotropic and steroid hormones need to be established in healthy subjects to provide a baseline for future clinical studies. We assayed sera from healthy men and women to determine p110 sErbB1 concentrations by acridinium-linked immunosorbent assay (ALISA). Follicle-stimulating hormone (FSH), estradiol, and testosterone concentrations were measured using the ACS:180 Immunoassay Analyzer. Luteinizing hormone (LH) and progesterone concentrations were quantified using the Access Immunoassay System. Unadjusted for age, p110 sErbB1 concentrations in healthy men and women do not differ significantly. However, sErbB1 concentrations show a strong age-gender interaction, increasing with age in men but decreasing with age in women. Consequently, sErbB1 concentrations are significantly higher in premenopausal women compared with either postmenopausal women or age-matched men and in age-matched men compared with postmenopausal women. Serum sErbB1 concentrations show significant negative associations with both FSH and LH concentrations in healthy women and a significant positive association with FSH concentrations in healthy men. Univariate linear regression models show that these respective gonadotropic hormones and age are independent predictors of sErbB1 concentrations in men and women. Multivariate models show that when age and FSH and LH concentrations are mutually adjusted for each other, they account for 22% of the variability observed in sErbB1 concentrations in healthy women. These data support the hypothesis that gonadotropic and steroid hormones may modulate ERBB1 expression in vivo and suggest that age- and gonadotropin-adjusted sErbB1 concentrations may be of clinical utility. Furthermore, these data demonstrate that gender, age, menstrual cycle phase, menopausal status, and exogenous hormone use must be considered when using serum p110 sErbB1 concentrations as cancer biomarkers.