Apoptosis Pathways in Ovarian Cancer

Tumour initiation and progression are driven by constitutively activated oncogenes mediating deregulation of the balance between cell deathand survival pathways. Among the most relevant signalling cascades activated in the majority of tumour types, the RAS/mitogen-activated protein kinase (Ras/MAPK), the phosphatidyl inositol-3kinase/protein kinase B (PI3K/PKB) and the protein kinases C (PKC) signalling cascades were postulated (Weinstein, 1987; Nicosia et al., 2003; Roberts and Der, 2007; McCubrey et al., 2007; Breitkreutz et al., 2007). These cascades define individual characteristics of particular tumours and consequently their individual responsiveness to cancer therapy. In this chapter, we will address the characteristics of the apoptotic signalling pathways in ovarian carcinomas. Particular attention will be given to the HRS family of tumour suppressor genes encoding proteins with phospholipase activity and suppressed in the majority of ovarian malignancies. We will describe signalling cascades down regulating two well-characterized members of this family H-REV107-1/HRLS3/PLA2G16 and TIG3/RARRES/RIG1 in tumour cells. Furthermore, potential therapeutic consequences of the re-expression of these genes defined as a class II tumour suppressors will be discussed.