Cancer : One Of The Most Adverse Effects Of Human Cancer

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Cancer is one of the most prevalent groups of disorders in the population in many countries worldwide. Epidemiologic studies have indicated that most human cancers are originally caused by environmental exposure to genotoxic agents (Doll et al., 1981). With respect to global human health hazard, arsenic (As) is one of the most important environmental single substance toxicants. It is a metalloid element and exists in organic and inorganic forms (iAs). Later is considered as a class I human carcinogen (IARC, 2004, 2012) and is associated with adverse effects dependent on dose, duration and exposure frequency. In particular chronic exposure to iAs is associated to an increased risk of skin, bladder, lung, kidney cancers, as well as…show more content…
The GSTs family of enzymes (i.e. GSTP1, GSTZ1, GSTM1, and GSTT1) is involved in arsenic metabolism and plays a role in the cellular response mechanism against oxidative stress. Arsenate is reduced to arsenite by two enzymes from the glutathione-S-transferase (GST) family: GSTO1 (Zakharyan et al., 2001) and GSTO2 (Whitbread et al., 2003) that use glutathione (GSH) as a reducing agent (Buchet and Lauwerys 1987) (Figure 1.2.). Arsenite is actively transported inside the cell by aquaporin’s (AQP) cell membrane proteins (Liu et al., 2002) and is then modified by methyltransferases (Marafante and Vahter, 1984) using S-adenosyl-methionine (SAM) as a methyl donor (Buchet and Lauwerys, 1985) to produce monomethylarsonous acid (MMA (III)) and dimethylarsinous acid (DMA (III)). Both become further oxidized to monomethylarsonic acid (MMA (V)) and dimethylarsinic acid (DMA (V)): predominant metabolites in urine (Aphosian and Aphosian, 2006).There are different biomarkers for assessing the genotoxicity. Biomarkers of effects are the quantifiable changes that an individual endures, which indicates an exposure to a compound and may indicate a resulting health effect. Genotoxicity endpoints are followed directly in exposed humans. The most frequently used endpoints includes chromosome aberrations, micronuclei, sister
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