Proteomic analysis of eutopic and ectopic endometriotic tissues based on isobaric peptide tags for relative and absolute quantification (iTRAQ) method

OBJECTIVE: The present study aimed at performing proteomic analysis of matched eutopic endometrium and ovarian endometrioid cysts from women with endometriosis in order to discover any abnormal protein expression related to the disease. DESIGN AND SETTING: The study included 8 women with stage III/IV endometriosis according to revised American Fertility Society (rAFS) classification and one woman with no signs of the disease as a reference. Proteomic analysis was performed using a novel isobaric tag-based methodology for relative and absolute peptide quantification (iTRAQ) coupled with multidimensional liquid chromatography and tandem mass spectrometry. RESULTS: The selection of 419 proteins was found in all endometriosis specimens. Using normal eutopic endometrium from woman without endometriosis as a reference, some proteins expressions were significantly increased in all endometriosis samples. They included collagen alpha 1(XIV), calmodulin, collagen alpha(VI), plexin, integrin alpha V beta 3, transgelin, desmin, and vimentin. The comparison of these proteins' expression in paired eutopic and ovarian endometriosis samples has revealed that only vimentin was significantly increased in ovarian endometrioma. CONCLUSIONS: It was confirmed that endometriosis is associated with different expression of proteins in endometriotic samples. Nevertheless, further studies seem to be necessary as they may reveal possible markers that would be useful in clinical diagnosis of the disease.