Detection of growth hormone doping by gene expression profiling of peripheral blood

miRNAs detection in equine plasma by quantitative polymerase chain reaction for doping control: Assessment of blood sampling and study of eca-miR-144 as potential erythropoiesis stimulating agent biomarker

Short half-life doping substances are, quickly eliminated and therefore difficult to control with traditional analytical chemistry methods. Indirect methods targeting biomarkers constitute an alternative to extend detection time frames in doping control analyses. Gene expression analysis (i.e., transcriptomics) has already shown interesting results in both humans and equines for erythropoietin (EPO), growth hormone (GH), and anabolic androgenic steroid (AAS) misuses. In humans, circulating cell-free microRNAs in plasma were described as new potential biomarkers for control of major doping agent (MDA) abuses. The development of a quantitative polymerase chain reaction (qPCR) method allowing the detection of circulating miRNAs was carried out on equine plasma collected on different type of tubes (EDTA, lithium-heparin [LiHep]). Although analyzing plasma collected in EDTA tubes is a standard method in molecular biology, analyzing plasma collected in LiHep tubes is challenging, as heparin is a reverse transcription (RT) and a PCR inhibitor. Different strategies were considered, and attention was paid on both miRNAs extraction quality and detection sensitivity. The detection of endogenous circulating miRNAs was performed and compared between the different types of tubes. In parallel, homologs of human miRNAs characterized as potential biomarkers of doping were sought in equine databases. The miRNA eca-miR-144, described as potential erythropoiesis stimulating agents (ESAs) administration candidate biomarker was retained and assessed in equine post-administration samples. The results about the qPCR method development and optimization are exposed as well as the equine miRNAs detection. To our knowledge, this work is the first study and the proof of concept of circulating miRNAs detection in plasma dedicated to equine doping control.

Pharmacogenomics applied to recombinant human growth hormone responses in children with short stature

We present current knowledge concerning the pharmacogenomics of growth hormone therapy in children with short stature. We consider the evidence now emerging for the polygenic nature of response to recombinant human growth hormone (r-hGH). These data are related predominantly to the use of transcriptomic data for prediction. The impact of the complex interactions of developmental phenotype over childhood on response to r-hGH are discussed. Finally, the issues that need to be addressed in order to develop a clinical test are described.

The Use and Abuse of Growth Hormone in Sports

GH is banned by the World Anti-Doping Agency as a performance-enhancing anabolic agent. Doping with GH likely began in the early 1980s and became more prevalent with the advent of recombinant technology well before any scientific evidence of benefit. The expectation that GH improves physical function stems from its anabolic and lipolytic properties. Athletic performance depends on muscle strength and the energy required to power muscle function. In recreational athletes, GH selectively improves anaerobic sprint capacity but has not been proven to significantly enhance muscle strength, power, or maximum rate of oxygen consumption. GH is secreted as a family of isoform peptides in a pulsatile manner reflecting intermittent secretion and rapid clearance. Its anabolic actions are largely mediated by IGF-I, which stimulates whole-body protein synthesis, including skeletal muscle and collagen proteins. Two methods have been validated for detecting GH abuse in athletes. The first (the isoform method) is based on distinguishing pure recombinant 22-kDa GH from the heterogeneous isoforms secreted from the pituitary. The second (the marker method) is based on measuring blood levels of GH-responsive proteins, specifically IGF-I and the N-terminal propeptide of type III collagen (P-III-NP). Only a handful of athletes have been caught since the implementation of GH doping tests in 2004. The low rate likely reflects the limitation of in-competition testing using current methods. Improved detection rates may be achieved by more out-of-competition testing, introducing athletes' biological passports, and the development of novel methods. Governance, operational, technical, and political factors influence the effectiveness of an anti-doping program.

Effect of summer daylight exposure and genetic background on growth in growth hormone-deficient children

The response to growth hormone in humans is dependent on phenotypic, genetic and environmental factors. The present study in children with growth hormone deficiency (GHD) collected worldwide characterised gene–environment interactions on growth response to recombinant human growth hormone (r-hGH). Growth responses in children are linked to latitude, and we found that a correlate of latitude, summer daylight exposure (SDE), was a key environmental factor related to growth response to r-hGH. In turn growth response was determined by an interaction between both SDE and genes known to affect growth response to r-hGH. In addition, analysis of associated networks of gene expression implicated a role for circadian clock pathways and specifically the developmental transcription factor NANOG. This work provides the first observation of gene–environment interactions in children treated with r-hGH.

Molecular effects of supraphysiological doses of doping agents on health

Supraphysiological doses of doping agents, such as T/DHT and GH/IGF-1, affect cellular pathways associated with apoptosis and inflammation.

Pharmacogenomics related to growth disorders

Growth disorders resulting in short stature are caused by a wide range of underlying pathophysiological processes. To improve height many of these conditions are treated with recombinant human growth hormone (rhGH). However, substantial inter-individual variability in growth response both in the short and long-term is recognised. Over the last decade, disease-specific growth prediction models have been developed that the clinician can use to define a child's potential response to rhGH and to optimise starting and maintenance doses of rhGH. These models, however, are not able to predict all the variations in treatment response. There has, therefore, been recent interest in using genetic information to contribute to the evaluation of responses to rhGH, including high-throughput technologies for assessing DNA markers (genome) and mRNA transcripts (transcriptome) as pharmacogenomic tools. This review will focus on how these pharmacogenomic approaches are being applied to growth disorders.

Optimization of extraction of circulating RNAs from plasma--enabling small RNA sequencing

There are several protocols and kits for the extraction of circulating RNAs from plasma with a following quantification of specific genes via RT-qPCR. Due to the marginal amount of cell-free RNA in plasma samples, the total RNA yield is insufficient to perform Next-Generation Sequencing (NGS), the state-of-the-art technology in massive parallel sequencing that enables a comprehensive characterization of the whole transcriptome. Screening the transcriptome for biomarker signatures accelerates progress in biomarker profiling for molecular diagnostics, early disease detection or food safety. Therefore, the aim was to optimize a method that enables the extraction of sufficient amounts of total RNA from bovine plasma to generate good-quality small RNA Sequencing (small RNA-Seq) data. An increased volume of plasma (9 ml) was processed using the Qiagen miRNeasy Serum/Plasma Kit in combination with the QIAvac24 Plus system, a vacuum manifold that enables handling of high volumes during RNA isolation. 35 ng of total RNA were passed on to cDNA library preparation followed by small RNA high-throughput sequencing analysis on the Illumina HiSeq2000 platform. Raw sequencing reads were processed by a data analysis pipeline using different free software solutions. Seq-data was trimmed, quality checked, gradually selected for miRNAs/piRNAs and aligned to small RNA reference annotation indexes. Mapping to human reference indexes resulted in 4.8±2.8% of mature miRNAs and 1.4±0.8% of piRNAs and of 5.0±2.9% of mature miRNAs for bos taurus.

Insights into the pathophysiology of catch-up compared with non-catch-up growth in children born small for gestational age: an integrated analysis of metabolic and transcriptomic data

Small for gestational age (SGA) children exhibiting catch-up (CU) growth have a greater risk of cardiometabolic diseases in later life compared with non-catch-up (NCU) SGA children. The aim of this study was to establish differences in metabolism and gene expression profiles between CU and NCU at age 4-9 years. CU children (n=22) had greater height, weight and body mass index standard deviation scores along with insulin-like growth factor-I (IGF-I) and fasting glucose levels but lower adiponectin values than NCU children (n=11; all P<0.05). Metabolic profiling demonstrated a fourfold decrease of urine myo-inositol in CU compared with NCU (P<0.05). There were 1558 genes differentially expressed in peripheral blood mononuclear cells between the groups (P<0.05). Integrated analysis of data identified myo-inositol related to gene clusters associated with an increase in insulin, growth factor and IGF-I signalling in CU children (P<0.05). Metabolic and transcriptomic profiles in CU SGA children showed changes that may relate to cardiometabolic risk.

A pharmacogenomic approach to the treatment of children with GH deficiency or Turner syndrome

OBJECTIVE

Individual sensitivity to recombinant human GH (r-hGH) is variable. Identification of genetic factors contributing to this variability has potential use for individualization of treatment. The objective of this study was to identify genetic markers and gene expression profiles associated with growth response on r-hGH therapy in treatment-naïve, prepubertal children with GH deficiency (GHD) or Turner syndrome (TS).

DESIGN

A prospective, multicenter, international, open-label pharmacogenomic study.

METHODS

The associations of genotypes in 103 growth- and metabolism-related genes and baseline gene expression profiles with growth response to r-hGH (cm/year) over the first year were evaluated. Genotype associations were assessed with growth response as a continuous variable and as a categorical variable divided into quartiles.

RESULTS

Eleven genes in GHD and ten in TS, with two overlapping between conditions, were significantly associated with growth response either as a continuous variable (seven in GHD, two in TS) or as a categorical variable (four more in GHD, eight more in TS). For example, in GHD, GRB10 was associated with high response (≥ Q3; P=0.0012), while SOS2 was associated with low response (≤ Q1; P=0.006), while in TS, LHX4 was associated with high response (P=0.0003) and PTPN1 with low response (P=0.0037). Differences in expression were identified for one of the growth response-associated genes in GHD (AKT1) and for two in TS (KRAS and MYOD1).

CONCLUSIONS

Carriage of specific growth-related genetic markers is associated with growth response in GHD and TS. These findings indicate that pharmacogenomics could have a role in individualized management of childhood growth disorders.

Human growth is associated with distinct patterns of gene expression in evolutionarily conserved networks

Background

A co-ordinated tissue-independent gene expression profile associated with growth is present in rodent models and this is hypothesised to extend to all mammals. Growth in humans has similarities to other mammals but the return to active long bone growth in the pubertal growth spurt is a distinctly human growth event. The aim of this study was to describe gene expression and biological pathways associated with stages of growth in children and to assess tissue-independent expression patterns in relation to human growth.

Results

We conducted gene expression analysis on a library of datasets from normal children with age annotation, collated from the NCBI Gene Expression Omnibus (GEO) and EBI Arrayexpress databases. A primary data set was generated using cells of lymphoid origin from normal children; the expression of 688 genes (ANOVA false discovery rate modified p-value, q < 0.1) was associated with age, and subsets of these genes formed clusters that correlated with the phases of growth – infancy, childhood, puberty and final height. Network analysis on these clusters identified evolutionarily conserved growth pathways (NOTCH, VEGF, TGFB, WNT and glucocorticoid receptor – Hyper-geometric test, q < 0.05). The greatest degree of network ‘connectivity’ and hence functional significance was present in infancy (Wilcoxon test, p < 0.05), which then decreased through to adulthood. These observations were confirmed in a separate validation data set from lymphoid tissue. Similar biological pathways were observed to be associated with development-related gene expression in other tissues (conjunctival epithelia, temporal lobe brain tissue and bone marrow) suggesting the existence of a tissue-independent genetic program for human growth and maturation.

Conclusions

Similar evolutionarily conserved pathways have been associated with gene expression and child growth in multiple tissues. These expression profiles associate with the developmental phases of growth including the return to active long bone growth in puberty, a distinctly human event. These observations also have direct medical relevance to pathological changes that induce disease in children. Taking into account development-dependent gene expression profiles for normal children will be key to the appropriate selection of genes and pathways as potential biomarkers of disease or as drug targets.

Hormones as doping in sports

Though we may still sing today, as did Pindar in his eighth Olympian Victory Ode, "… of no contest greater than Olympia, Mother of Games, gold-wreathed Olympia…", we must sadly admit that today, besides blatant over-commercialization, there is no more ominous threat to the Olympic games than doping. Drug-use methods are steadily becoming more sophisticated and ever harder to detect, increasingly demanding the use of complex analytical procedures of biotechnology and molecular medicine. Special emphasis is thus given to anabolic androgenic steroids, recombinant growth hormone and erythropoietin as well as to gene doping, the newly developed mode of hormones abuse which, for its detection, necessitates high-tech methodology but also multidisciplinary individual measures incorporating educational and psychological methods. In this Olympic year, the present review offers an update on the current technologically advanced endocrine methods of doping while outlining the latest procedures applied-including both the successes and pitfalls of proteomics and metabolomics-to detect doping while contributing to combating this scourge.

Evolving concepts and techniques for anti-doping

Technical advances are being made in many areas of biotechnology and genetics that are facilitating the detection of doping in sport. These improvements have been catalyzed by the need to counter the ever-increasing sophistication of the community of athletes and their retinues who are intent on the illicit use of physical, pharmacological and genetic tools and methods to enhance athletic performance, in contravention of established international ethical and legal standards and of international treaty. The methods described in this article present a partial and general picture of only some of these advances.

A quantitative approach for assessing significant improvements in elite sprint performance: has IGF-1 entered the arena?

The introduction of doping substances and methods in sports triggers noticeable effects on physical performance in metric sports. Here, we use time series analysis to investigate the recent development in male and female elite sprinting performance. Time series displaying the average of the world's top 20 athletes were analyzed employing polynomial spline functions and moving averages. Outstanding changes in performance over time were statistically analyzed by Welch's t-test and by Cohen's measurements of effect. For validation we exemplarily show that our analysis is capable of indicating the effect of the introduction of in- and out-of-competition doping testing on women's shot put as well as the effects of the market introduction of erythropoietin (EPO) and the introduction of EPO and continuous erythropoiesis receptor activator (CERA) testing on 5000 m top 20 male performances. Time series analysis for 100 m men reveals a highly significant (p < 0.001) drop by more than 0.1 s from 2006 to 2011 with a large effect size of 0.952. This is roughly half of the effect size that can be found for the development of the 5000 m performance during the introduction of EPO between 1991 and 1996. While the men's 200 m sprinting performance shows a similar development, the women's 100 m and 200 m sprinting performances only show some minor abnormalities. We will discuss here why the striking sex-specific improvement in sprinting performance is indicative for a novel, very effective doping procedure with insulin-like growth factor-1 (IGF-1) being the primary candidate explaining the observed effects.

Detection of EPO gene doping in blood

Gene doping--or the abuse of gene therapy--will continue to threaten the sports world. History has shown that progress in medical research is likely to be abused in order to enhance human performance. In this review, we critically discuss the progress and the risks associated with the field of erythropoietin (EPO) gene therapy and its applicability to EPO gene doping. We present typical vector systems that are employed in ex vivo and in vivo gene therapy trials. Due to associated risks, gene doping is not a feasible alternative to conventional EPO or blood doping at this time. Nevertheless, it is well described that about half of the elite athlete population is in principle willing to risk its health to gain a competitive advantage. This includes the use of technologies that lack safety approval. Sophisticated detection approaches are a prerequisite for prevention of unapproved and uncontrolled use of gene therapy technology. In this review, we present current detection approaches for EPO gene doping, with a focus on blood-based direct and indirect approaches. Gene doping is detectable in principle, and recent DNA-based detection strategies enable long-term detection of transgenic DNA (tDNA) following in vivo gene transfer.

Growth hormone doping in sports: a critical review of use and detection strategies

GH is believed to be widely employed in sports as a performance-enhancing substance. Its use in athletic competition is banned by the World Anti-Doping Agency, and athletes are required to submit to testing for GH exposure. Detection of GH doping is challenging for several reasons including identity/similarity of exogenous to endogenous GH, short half-life, complex and fluctuating secretory dynamics of GH, and a very low urinary excretion rate. The detection test currently in use (GH isoform test) exploits the difference between recombinant GH (pure 22K-GH) and the heterogeneous nature of endogenous GH (several isoforms). Its main limitation is the short window of opportunity for detection (~12-24 h after the last GH dose). A second test to be implemented soon (the biomarker test) is based on stimulation of IGF-I and collagen III synthesis by GH. It has a longer window of opportunity (1-2 wk) but is less specific and presents a variety of technical challenges. GH doping in a larger sense also includes doping with GH secretagogues and IGF-I and its analogs. The scientific evidence for the ergogenicity of GH is weak, a fact that is not widely appreciated in athletic circles or by the general public. Also insufficiently appreciated is the risk of serious health consequences associated with high-dose, prolonged GH use. This review discusses the GH biology relevant to GH doping; the virtues and limitations of detection tests in blood, urine, and saliva; secretagogue efficacy; IGF-I doping; and information about the effectiveness of GH as a performance-enhancing agent.

Somatotropic gene response to recombinant growth hormone treatment in buffalo leucocytes

The use of recombinant bovine growth hormone (rbGH) to increase milk yield in cows is banned in some countries. In others, where it is authorised, it has triggered harsh debates on labelling of dairy products. If many studies have been performed on bovines, there is a lack of information on buffaloes, which are sometimes treated with rbGH and re-present an important economical resource for dairy products in some countries. Analytical methods with legal value for surveillance of rbGH treatments do not yet exist. Research on gene expression biomarkers is one of the most promising approaches to this purpose. For this reason, we treated five buffaloes for 10 weeks with a sustained-release formulation of rbGH and analysed the response of 20 somatotropic axis genes in leucocytes by real-time polymerase chain reaction. Overall changes in gene expression levels were of low magnitude and sometimes affected by the 'time' factor. Only the IGFBP-1 gene showed a significant under-expression (about two-fold; p <0.001) in treated animals. Taken together, these results give evidence that expression analysis of the somatotropic axis genes in leucocytes is little helpful for discrimination of rbGH-treated buffaloes, but do not exclude that another array of genes could provide useful patterns of variation.

Somatotropic gene response to recombinant growth hormone treatment in buffalo leucocytes

The use of recombinant bovine growth hormone (rbGH) to increase milk yield in cows is banned in some countries. In others, where it is authorised, it has triggered harsh debates on labelling of dairy products. If many studies have been performed on bovines, there is a lack of information on buffaloes, which are sometimes treated with rbGH and re-present an important economical resource for dairy products in some countries. Analytical methods with legal value for surveillance of rbGH treatments do not yet exist. Research on gene expression biomarkers is one of the most promising approaches to this purpose. For this reason, we treated five buffaloes for 10 weeks with a sustained-release formulation of rbGH and analysed the response of 20 somatotropic axis genes in leucocytes by real-time polymerase chain reaction. Overall changes in gene expression levels were of low magnitude and sometimes affected by the 'time' factor. Only the IGFBP-1 gene showed a significant under-expression (about two-fold; p <0.001) in treated animals. Taken together, these results give evidence that expression analysis of the somatotropic axis genes in leucocytes is little helpful for discrimination of rbGH-treated buffaloes, but do not exclude that another array of genes could provide useful patterns of variation.

OMICS-strategies and methods in the fight against doping

During the past decade OMICS-methods not only continued to have their impact on research strategies in life sciences and in particular molecular biology, but also started to be used for anti-doping control purposes. Research activities were mainly reasoned by the fact that several substances and methods, which were prohibited by the World Anti-Doping Agency (WADA), were or still are difficult to detect by direct methods. Transcriptomics, proteomics, and metabolomics in theory offer ideal platforms for the discovery of biomarkers for the indirect detection of the abuse of these substances and methods. Traditionally, the main focus of transcriptomics and proteomics projects has been on the prolonged detection of the misuse of human growth hormone (hGH), recombinant erythropoietin (rhEpo), and autologous blood transfusion. An additional benefit of the indirect or marker approach would also be that similarly acting substances might then be detected by a single method, without being forced to develop new direct detection methods for new but comparable prohibited substances (as has been the case, e.g. for the various forms of Epo analogs and biosimilars). While several non-OMICS-derived parameters for the indirect detection of doping are currently in use, for example the blood parameters of the hematological module of the athlete's biological passport, the outcome of most non-targeted OMICS-projects led to no direct application in routine doping control so far. The main reason is the inherent complexity of human transcriptomes, proteomes, and metabolomes and their inter-individual variability. The article reviews previous and recent research projects and their results and discusses future strategies for a more efficient application of OMICS-methods in doping control.

A polymerase chain reaction-based methodology to detect gene doping

The non-therapeutic use of genes to enhance athletic performance (gene doping) is a novel threat to the world of sports. Skeletal muscle is a prime target of gene therapy and we asked whether we can develop a test system to produce and detect gene doping. Towards this end, we introduced a plasmid (pCMV-FAK, 3.8 kb, 50 μg) for constitutive expression of the chicken homologue for the regulator of muscle growth, focal adhesion kinase (FAK), via gene electro transfer in the anti-gravitational muscle, m. soleus, or gastrocnemius medialis of rats. Activation of hypertrophy signalling was monitored by assessing the ribosomal kinase p70S6K and muscle fibre cross section. Detectability of the introduced plasmid was monitored with polymerase chain reaction in deoxyribonucleic acids (DNA) from transfected muscle and serum. Muscle transfection with pCMV-FAK elevated FAK expression 7- and 73-fold, respectively, and increased mean cross section by 52 and 16% in targeted muscle fibres of soleus and gastrocnemius muscle 7 days after gene electro transfer. Concomitantly p70S6K content was increased in transfected soleus muscle (+110%). Detection of the exogenous plasmid sequence was possible in DNA and cDNA of muscle until 7 days after transfection, but not in serum except close to the site of plasmid deposition, 1 h after injection and surgery. The findings suggest that the reliable detection of gene doping in the immoral athlete is not possible unless a change in the current practice of tissue sampling is applied involving the collection of muscle biopsy close to the site of gene injection.