Globally, 10-15 % of women of reproductive age suffer from endometriosis. The current ‘gold standard’ for diagnosis is still laparoscopy or laparotomy coupled with histological confirmation. Despite numerous research efforts, pathogenesis and an early, simple and definitive diagnosis of endometriosis remain elusive.Tokushige et al. (2011) described the finding of a novel urinary protein biomarker for endometriosis. This finding has exciting clinical implications. Furthermore, successful identification of urinary biomarkers may help to elucidate key molecular networks responsible for the pathogenesis of endometriosis.
We wish to establish whether there is a difference in the urinary proteome from first pass morning samples compared to urine collected during laparoscopic surgery. Ultimately, our overall objective is to identify specific and sensitive urinary biomarkers able to screen different stages of endometriosis.
Matched pairs of urine samples were collected from three patients, first urine on the morning of scheduled surgery and a second sample during surgery. Extraction and concentration of proteins were achieved using Amicon Ultra 15 Filter, 10kDa MWCO (molecular weight cut-off). Off-gel prefractionation was used to obtain three fractions (pH4.6-5.4, pH5.4-6.2 and pH6.2-7.0), and further subjected to 2D gel electrophoresis. Following gel image analysis (Progenesis SameSpot, Nonlinear Dynamics), proteins of interest were subjected to trypsin digestion and identified by MALDI-TOF mass spectrometry (MS; Voyager, AB Sciex, Australia) and MASCOT (Matrix Science, UK).
Results & Conclusions:
Detected protein spots of interest are currently undergoing MS identification. Further analyses of results are expected to lead us to assess and nominate biomarkers, which are specific and sensitive for the diagnosis and staging of endometriosis. Reduction in proteomic complexity, coupled with 2D gel electrophoresis, offered clear protein spot separation from patients with and without endometriosis. Successful identification should allow development of a non-invasive screening biomarker for endometriosis, suitable for use in clinical practice.