Involvement of Oncogenes in Carcinogenesis

Recent advances in cancer research have established the involvement of transforming genes (oncogenes) in the multistep process of carcinogenesis. Over the span of several decades, epidemiological studies have drawn attention to the fact that there is a high incidence of cancer among individuals exposed to mutagens in the workplace. The effect of many of these carcinogens, both physical and chemical, has been shown to result in direct alteration of the DNA in target cells by induction of point mutations or chromosomal translocations, suggesting a crucial role for genes in carcinogenesis (1,2). The observation that human tumors contain oncogenes activated by these mechanisms has led to the speculation that the direct mutagenic effect of the carcinogen occurs at the level of activation of the proto-oncogene, bestowing upon it the ability to cause phenotypic transformation