Potential tumor markers

Malignant melanocytes present defective melanosomes and tend to exhibit up-regulated melanogenesis. Melanogenuria (in the form of dark urine) is observed in some patients with widespread disease. End-product pigments, enzymes and melanin precursors or intermediates of the melanogenesis have therefore been measured in urine and blood from melanoma patients for more than 30 years. 

Based on its key regulating role, the melanocyte-specific enzyme tyrosinase has been evaluated by the measurement of its activity (abandoned due to poor sensitivity), substrates and/or metabolites (L-tyrosine, l-DOPA) and, more recently, by the detection and now 

---

To date, 16 GST isozymes have been found in humans [48]. Studies of several cancer tissues have revealed the overexpression of different GST isozymes, with GST Pl-1 (GST Pi, GST ji) being the most predominant. For this reason, GST Pl-1 is regarded as a potential tumor marker [5,49-53]. The high expression levels of GST Pl-1 (up to 2.7% of the total cytosolic protein [52]), combined with its detoxification role against xenobiotics, make GST Pl-1 a major player responsible for drug resistance in patients undergoing anticancer chemotherapy [49]. 

Similar to tumor markers discussed above, a number of hazardous proteins are not immediately linked to an accompanying nucleic acid and therefore are prime targets for IPCR. These are interesting examples of how the clinical importance of IPCR is not limited to the diagnosis of diseases. IPCR was reported as a useful tool for the prevention of intoxications or infections because of highly sensitive detection of potentially dangerous compounds, especially in food analysis. 

Diagnostic potential in bladder cancer of a panel of tumor markers (calreticulin, gamma-synuclein, and catechol-o-methyltransferase) identified by proteomic analysis. Cancer Sci. 95, 955-961. 

The potential uses of tumor markers are summarized in Table 23-3. In general, tumor markers may be used for diagnosis, prognosis, and monitoring the effects of therapy and as targets for localization and therapy. Ideally a tumor marker should be produced by the tumor cells and be... 

PSA is one of the most promising tumor markers of this decade. It is one of the few organ-specific tumor markers. Prostate cancer is the leading cancer in older men. When detected early (organ confined), it is potentially curable by radical prostatectomy. Therefore early detection is important. The role of PSA in prostate cancer has been reviewed. ... 

Several proteins having tumor marker potential are listed in Table 23-12. Included in this group of tumor markers are proteins that are not enzymes, hormones, or high in carbohydrate content. Additional research is required to assess the clinical usefulness of most of these markers. 

Andrianifahanana M, Moniaux N, Schmied BM, et al. Mucin (MUC) gene expression in human pancreatic adenocarcinoma and chronic pancreatitis a potential role of MUG4 as a tumor marker of diagnostic significance. Clin Cancer Res. 2001 7 4033-4040. 

This possibility to evaluate the potential biomarker masses directly in the histological context is one of the major strengths of MALDI imaging. This allows immediate evaluation whether the mass in question is indeed a tumor-marker or inflammation marker. 

---