Deregulation of the Expression of MTDH in Gastric Cancers

Gastric cancer is the third most frequent cause of cancer mortality in the world (Keeney et al., 2006). Although its incidence varies between different geographical areas of Iran (Malekzadeh et al., 2009), it is the leading cause of cancer-related mortality in Iran (The National Cancer Registry, 2008). The main environmental factors of gastric cancer in Iran are high H.pylori prevalence, high dietary concentration of salt and smoking (Malekzadeh et al., 2009). Moreover, conventional therapeutic methods do not provide any survival benefit for the majority of Iranian patients with gastric cancer because it is being diagnosed in advanced stages of the disease (Malekzadeh et al., 2009). Localized at chromosome 8q22, the human MTDH gene has been reported to be amplified in a number of malignancies such as malignant glioma (Kim et al., 1995), hepatocellular carcinoma (HCC) (Poon et al., 2006), and breast cancer (Wang et al., 2005). Intriguingly, expression analysis in cell lines and in patient-derived tumor samples revealed that MTDH significantly elevated in breast carcinoma (Li et al., 2008), HCC (Yoo et al., 2009), neuroblastoma (Lee et al., 2009), and malignant glioma (Liu et al., 2010) cell lines and tumor samples compared with their normal counterparts. Furthermore, it has been reported that MTDH plays important roles in multiple biological processes in the course of tumorigenesis via modulating of multiple signalling pathways (Lee et al.,