| Popis: |
Recent studies on carcinogenesis have revealed that genetic alteration, including both activation of proto-oncogenes and inactivation of anti-oncogenes, are crucial for initiation and progression of human malignant lesions. Glioblastoma multiforme (astrocytoma grades III and IV) is recognized as the major malignant type of tumor of the human brain. Several proto-oncogenes were found to be activated in glioblastoma. The epidermal growth factor (EGF) receptor gene (c-erbB gene) was amplified in about one-third of these tumors [1,2]. Other oncogenes or possible oncogenes, c-myc [3], N-myc [4], gli [5] and ros-1 [6] genes were also observed to be amplified or rearranged. However, the presence of activation of the latter four genes in glioblastoma is thought to be rare. Thus, the activation of proto-oncogenes in the DNA level, in about one-half of the glioblastoma multiforme in humans is still unclear. Furthermore, although the EGF receptor gene was found to be frequently amplified in these tumors, it has not been fully determined whether or not these amplified genes are changed structurally and functionally. |
