Novel biomarkers of human growth hormone action from serum proteomic profiling using protein chip mass spectrometry

Context: The detection of exogenous human GH (hGH) administration in athletes poses unique analytical problems, because its short circulating half-life provides only a brief opportunity to detect the administered hormone above endogenous levels. Measurement of novel GH-regulated serum protein biomarkers might provide an indirect method to detect exogenous GH. Objective: The objective of this study was to identify new serum biomarkers of GH administration using proteomic profiling. Design: Sera from a previously reported, double-blind, placebo-controlled GH administration trial were analyzed by protein chip mass spectrometry. Setting: The study was performed at clinical research centers. Subjects: Sixty healthy subjects, aged 18-40 yr, who were not elite athletes, were studied. Interventions: Placebo or recombinant hGH treatment (0.1 or 0.2 IU/kg center dot d; 20 subjects/group) was administered for 4 wk, followed by an 8-wk washout period. Main Outcome Measures: Protein mass profiles were determined on immobilized Cu2+ chips on d 0 and 21 of GH administration, and multivariate analysis was used to classify subjects into GH and placebo administration groups. Results: When assessed by cross-validation, the classification performance of classifiers based on multivariate analysis of several GH-regulated peaks performed no better than classifiers based on the single best peak. This peak, a prominent biomarker of 15.1 kDa, was purified and identified as hemoglobin alpha-chain. The time course of the GH response of this biomarker is similar to that of other GH-dependent markers, such as IGF-I. Conclusion: This study demonstrates that protein mass profiling is an effective tool for the detection of GH administration and suggests that measurement of hemoglobin alpha-chain may have utility as a novel serum biomarker of GH action.