Direct tissue proteomics in human diseases: potential applications to melanoma research

Although the rates of cancer are stabilizing, the number of new invasive melanoma continues to rise. Melanoma represents only 4% of all skin cancers, but nearly 80% of skin cancer deaths. In loss of potential productive life-years, it is second only to adult leukemia. Once melanoma spreads to regional and distant sites, the chance of cure decreases significantly. Unfortunately, current diagnostic and prognostic methods are often inadequate. More precise staging and disease characterization will lead to new and more rational approaches to treatment. Proteomics is a fast-growing discipline in biomedicine that can be defined as the global characterization and differential expression of the entire protein complement of a cell, tissue or organism. Despite major advances in molecular approaches to the diagnosis and prognostication of human diseases such as melanoma, there remain significant obstacles in applying the proteomic technologies to clinical samples to extract important biological information. The application of a shotgun-based technique termed direct tissue proteomics with improved extraction protocol of proteins from formalin-fixed paraffin-embedded tissue would enable retrospective biomarker investigations of the vast archive of pathologically characterized clinical samples that exist worldwide. Combination of this direct tissue proteomics method with laser-capture microdissection may assist in the discovery of new biomarkers and may lead to new diagnostic tests, risk assessment and staging tools as well as improvement in therapeutics. In addition, these tools can provide a molecular characterization of melanoma, which may enable individualized molecular therapy.