cell line secretome is a good representation of an actual tumor in its specific microenvironment and a standardized cell line is not illustrative of the heterogeneity of a real tumor. Analysis of proximal fluids can give a better idea of a human tumor secretome, but this method also has its drawbacks. Procedures for collecting proximal fluids still need to be standardized and non-malignant controls are needed. In addition, environmental and genetic differences between patients can complicate analysis. Secretomic analysis has discovered potential new biomarkers in many cancer types, including lung cancer, liver cancer, pancreatic cancer, colorectal cancer, prostate cancer, and breast cancer. Prostate-specific antigen (PSA), the current standard biomarker for prostate cancer, has a low diagnostic specificity – PSA levels can not always discriminate between aggressive and non-aggressive cancer – and so a better biomarker is greatly needed. Using secretomic analysis of prostate cell lines, one study was able to discover multiple proteins found in higher levels in the serum of cancer patients than in healthy controls. There is also a great need for biomarkers for the detection of breast cancer – currently biomarkers only exist for monitoring later stages of cancer. Secretomic analysis of breast cancer cell lines led to the discovery of the protein ALCAM as a new biomarker with promising diagnostic potential. Assisted reproductive technologies Analyzing the human embryonic secretome could be helpful in finding a non-invasive method for determining viability of embryos. In IVF, embryos are assessed on morphological criteria in an attempt to find those with high implantation potential. Finding a more quantitative method of assessment could help reduce the number of embryos used in IVF, thereby reducing higher order pregnancies. For example, one study was able to develop secretome fingerprints for many blastocysts and found 9 proteins that could distinguish between blastocysts with normal and abnormal numbers of chromosomes. This type of analysis could help replace preimplantation genetic screening (PGS), which involves biopsy of embryonic cells and can be harmful to development. References Proteomics Secretion