Biology And Biomedical Sciences BIOL 2960 Lecture Notes - Lecture 39: Tumor Suppressor Gene, Tumor Progression, Genome Instability
7 May 2017
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Document Summary
Transformation of normal human cells in culture to cancer cells requires participation of genes that are associated with 4 major pathways: ras, rb, p53, and telomere maintenance (robert weinberg -- mit) Cultured human cells quit dividing after about 50-60 population doublings. Accumulated stress results in activation of cdk inhibitors; senescence can be overcome by inactivating rb and p53. Erosion of telomeres results in genome instability; crisis can be overcome by expressing telomerase. Normal adult somatic cells do not express telomerase activity. - inactivating telomerase in cancer cells causes them to stop growing! (treat with sirna) Cancer is a progressive disease that requires multiple genetic lesions. It"s difficult to get access to pre-cancerous lesions because you can"t really isolate them until the cancer shows up. Progression involves both oncogene activation and tumor suppressor gene inactivation. Cancers evolve through clonal selection of increasingly aggressive tumor cells through accumulation of mutations, combinations of oncogene activation and tumor suppressor gene inactivation.
