ABSTRACT
Carcinogenesis is a multistep process, caused by combination of environmental and genetic factors, leading to a series of genetic and epigenetic changes occurring at various stages in the development and progression of the disease (Aznavoorian et al., 1993). Cancer cells arise from a single transformed cell, which has undergone genetic and epigenetic changes. Thus cancerous state is a result of several sequential events triggered by various factors including genetic predispositions, transformation by viruses, radiation and/or by certain chemicals. Many genetic and cytoplasmic events including de activation of tumor suppressor genes such as P53 or Rb, triggers various events leading to cancer (Harris and Levine, 2005).
