Novel Biomarkers of Human Growth Hormone Action from Serum Proteomic Profiling Using Protein Chip Mass Spectrometry

Abstract

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. The objective of this study was to identify new serum biomarkers of GH administration using proteomic profiling. Sera from a previously reported, double-blind, placebo-controlled GH administration trial were analyzed by protein chip mass spectrometry. The study was performed at clinical research centers. Sixty healthy subjects, aged 18-40 yr, who were not elite athletes, were studied. Placebo or recombinant hGH treatment (0.1 or 0.2 IU/kg.d; 20 subjects/group) was administered for 4 wk, followed by an 8-wk washout period. Protein mass profiles were determined on immobilized Cu(2+) chips on d 0 and 21 of GH administration, and multivariate analysis was used to classify subjects into GH and placebo administration groups. 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. 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.