THE ONCOGENES OF NASOPHARYNGEAL CARCINOMA

Abstract

The development of a normal cell into a cancer cell is a complex, multistep process involving alterations in cellular genetic material. Genetic analysis has led to the identification of many genes that are involved in this process and these fall into two groups, namely the oncogenes and the anti-oncogenes. Nasopharyngeal carcinoma (NPC) is an aggressive tumour of the head and neck with a very high rate of systemic dissemination. To date, it has been shown that the Epstein Barr Virus is an etiological agent for NPC. Environmental and dietary factors arc also causal factors of NPC; working in concert with the Human Lymphocyte Antigen system, all of which explains the higher incidence of NPC among the Chinese especially the Cantonese dialect group. Abnormalities of anti-oncogenes such as the retinoblastorna, p53 and erb-A genes have been demonstrated in many cancers like hepatocellular carcinoma, breast cancer and small cell lung cancer to name a few. However, their role in the carcinogenesis of NPC has been poorly understood. The results of this study revealed that certain regions within these anti-oncogenes arc not causally involved in the progression of NPC. Through Polymerase Chain Reaction amplification, sequence analysis and Southern blotting, point mutations and chromosomal abnormalities which are common in other cancer types were not observed in NPC biopsies. This however docs not rule out the possibility of mutations in other regions of the anti-oncogenes.