Prostate cancer proteomics: clinically useful protein biomarkers and future perspectives

Introduction: Although prostate cancer constitutes one of the most important, death-related diseases in the male population, there is still a need for identification of sensitive biomarkers that could precociously detect the disease and differentiate aggressive from indolent cancers, in order to decrease overtreatment. Proteomics research has improved understanding on mechanisms underlying tumorigenesis, cancer cells migration and invasion potential, and castration resistance. This review has focused on proteomic studies of prostate cancer published in the recent years, with a special emphasis on determination of biomarkers for cancer progression and diagnosis. Areas covered: Shotgun and targeted-proteomic studies of prostate cancer in different matrices are reviewed, i.e., prostate tissue, prostate cell lines, blood (serum and plasma), urine, seminal plasma, and exosomes. The most important biomarkers for cancer diagnosis and aggressiveness characterization are highlighted. Expert commentary: In general, results demonstrate alteration in cell cycle control, DNA repair, proteasomal degradation, and metabolic activity. However, these studies suffer from low reproducibility due to heterogeneity of the cancer itself, as well as to techniques utilized for protein identification/quantification. Downstream confirmatory studies in separate cohorts are warranted in order to demonstrate accuracy of these results.Sao Paulo Research Foundation (FAPESP) [2014/11493-0]National Council for Scientific and Technological Development (CNPq) [306616/2013-0]Univ Fed Sao Paulo UNIFESP, Sao Paulo Hosp, Human Reprod Sect, Dept Surg,Div Urol, Sao Paulo, BrazilUniv Fed Sao Paulo UNIFESP, Sao Paulo Hosp, Human Reprod Sect, Dept Surg,Div Urol, Sao Paulo, BrazilFAPESP [2014/11493-0]CNPq [306616/2013-0]Web of Scienc

Separating the chaff from the wheat: antibody-based removal of DNA-fragmented sperm

Abstract STUDY QUESTION Is it possible to remove sperm with damaged DNA from a semen sample? SUMMARY ANSWER By using immunomagnetic cell sorting that targets the sperm head-bound epididymal sperm-binding protein 1 (ELSPBP1), it was possible to produce an ELSPBP1(−) sperm fraction characterized by consistently lower levels of sperm DNA fragmentation (SDF). WHAT IS KNOWN ALREADY In bovines, ELSPBP1 is bound to dead spermatozoa. Human ejaculates with high SDF have increased detected levels of sperm ELSPBP1 when compared to ejaculates with low native SDF. STUDY DESIGN, SIZE, DURATION We recruited 267 patients who were referred to the clinic for conjugal infertility. After applying exclusion criteria, such as fever within 90 days of the study, history of systemic diseases, alterations or surgical interventions to the genital tract and use of cigarette or drugs, a total of 133 patients were included. A total of 52 samples were used for the evaluation of sperm ELSPBP1 levels (Sub-study 1), 41 samples for determination of ELSPBP1 location in human sperm (Sub-study 2), and 40 samples for immunomagnetic cell sorting targeting ELSPBP1, to produce ELSPBP1(−) (without ELSPBP1) and ELSPBP1(+) (with ELSPBP1) fractions (Sub-study 3). Samples were collected between July 2016 and September 2019. PARTICIPANTS/MATERIALS, SETTING, METHODS In Sub-study 1, sperm ELSPBP1 levels were assessed by western blotting. For Sub-study 2, ELSPBP1 was localized in sperm by immunocytochemistry. Finally, for Sub-study 3, sperm were selected based on incubation of semen samples with antibody-coated magnetic microspheres targeting ELSPBP1. Two fractions were produced (with or without ELSPBP1), and these sub-populations were submitted to an alkaline Comet assay for determination of SDF. MAIN RESULTS AND THE ROLE OF CHANCE Men with high SDF presented higher sperm ELSPBP1 levels when compared to the control group (low SDF), while no difference between groups was observed in seminal plasma. ELSPBP1 was located in the head region of human sperm. The ELSPBP1(+) fractions presented high and variable levels of SDF, while their paired ELSPBP(−) fractions presented consistently low SDF. LIMITATIONS, REASONS FOR CAUTION This work did not validate the levels of ELSPBP1 in other functional alterations of sperm, such as acrosome integrity or mitochondrial activity. Moreover, this is still a pre-clinical study, intended to demonstrate proof-of-concept that ELSPBP1 selects sperm with low DNA fragmentation; further investigation is warranted to demonstrate safety for use in ART. Sperm fractions were not assessed for sperm vitality. A clinical trial is still necessary for these findings to be extrapolated to outcomes in ART. WIDER IMPLICATIONS OF THE FINDINGS Our findings demonstrate that ELSPBP1 is associated with sperm with higher levels of DNA fragmentation. The finding that the sperm membrane can reflect alterations in DNA integrity could give rise to a novel molecular method for sperm preparation prior to use of assisted reproductive procedures. Moreover, the detection of sperm-bound ELSPBP1 could serve as an indirect method for the determination of DNA fragmentation. STUDY FUNDING/COMPETING INTEREST(S) L.B.B. was a recipient of a Ph.D. scholarship from the Sao Paulo Research Foundation—FAPESP (process number 2016/05487-3). R.P.B. is a recipient of a Scientific Productivity scholarship from the Brazilian National Council for Scientific and Technological Development—CNPq (process number 306705/2017-6). The authors have no conflict of interest to disclose. TRIAL REGISTRATION NUMBER N/A. </jats:sec