Tumoral Markers in Prostate Cancer

In Mexico, in 70% of cases, the prostate cancer (PCa) is found in advanced stage. PCa currently occupies second place in frequency of cancer in men, surpassed only by skin cancer, and is the second principal cause of death in men after of lung cancer (Hall et al., 2005). Reactive oxygen species (ROS) such as superoxide (O2 −) and hydrogen peroxide (H2O2) are found in a large number of tumors and in high levels they induce cell death, apoptosis, senescence and angiogenesis (Ushio-Fukai & Nakamura, 2008). One of the major sources of ROS is NADPH oxidase (NOX). The NOX are a family of enzymes that are found in various tissues. The NOX receives an electron from NADPH generating O2 (Bánfi et al., 2001). Xia et al, Lim et al. and Brar et al. found that some NOX isozymes increase in association with ROS-production and tumor progression in ovarian and human colon cancer and in DU-145 cells of PCa, respectively (Brar et al., 2003; Lim et al., 2005; Xia et al., 2007). Cells have different antioxidant systems including low molecular weight antioxidant molecules and various antioxidant enzymes. Superoxide dismutase (SOD) catalyses the dismutation of O2  into H2O2 that can be transformed into H2O and O2 by catalase (CAT) (Genkinger et al., 2006). Mn-SOD is the major antioxidant in the mitochondria and is essential to the vitality of mammalian cells. In many types of tumor cells has been found to contain high levels of Mn-SOD, Cu/Zn-SOD or CAT expression compared to their nonmalignant counterpart such as in human tumor cancer cells of esophageal, gastric, ovary, breast, neuroblastoma, osteosarcoma, melanoma, pleura and leukemia (Grigolo et al., 1998; Janssen et al., 2000; Starcevic et al., 2003; Qian et al., 2005, López Laur et al., 2008). However, the role of these enzymes in carcinogenesis remains unclear. On the other hand, iNOS or NOS-2 is an inducible isoform of nitric oxide synthases (NOS). All isoforms of NOS catalyze the reaction of L-arginine, NADPH and oxygen to nitric oxide (NO), L-citrulline and NADP. NO is a lipophilic physiological messenger wich regulate a variety of cellular responses and may exert its cellular action by cGMP-dependent as well as by cGMP-independent pathways (Stamler, 1994). The expression of iNOS has been found to be increased in a variety of human cancers such as colon, stomach, brain and breasts cancers (Alderton et al., 2001; Church & Fulton, 2006) by multiple mechanisms that control their activity (Stamler, 1994; Friebe & Koesling, 2003).