234- Oncogenes and tummor suppressors Flashcards
by what processes can proto-oncogenes be converted to oncogenes
1- Direct mutation (missense, nonsense, translocation, gene amplification)
2- Over-expression (de-regulation of transcription or impaired degradation)
Compare oncogenes and tumor suppressors in terms of dominant/recessive and gain/loss of function
oncogenes are usually dominant and result in GOF
Tumor suppressors are usually recessive and result in LOF
what is oncogene addiction? how do you prove it?
tumor cells dependent on a particular signal transduction pathway or molecule for survival. Proven by tumor regression following selective inhibition of a particular molecular target
four pieces of experimental evidence that tell you a cell has undergone oncogene transformation
focus formation in agar, immortalization (telomerase), growth in serum (nutrient) free conditions, tumor induction in nude mice
what are the main categories of oncogenes
grwoth factors, growth factor receptors, signal transducers, transcription factors, cell cycle proteins, regulators of apoptosis
talk about the ras pathway
transducer that is associated with RTKs. Inactive is bound to GDP, binding at receptor activates ras by replacing GDP with GTP. Growth signals sent to nucleus. ras inactivates itself by cleaving GTP to GDP. GTPase activating protein (GAP) augments this but mutated ras inhibits GAP and you get increased growth signals
what is PI3K?
lipid kinase that is controlled by Ras. Pathway is often activated in cancer
why might a cell that has a mutated EGFR not respond to anti-EGFR treatment
Ras mutation which is downstream
what is Myc? what are three important kinds and their associated tumors?
nuclear transcription factor. cMyc translocation (8;14) leads to burkitt lymphoma. N-Myc amplification leads to neuroblastoma. L-Myc amplification leads to Lung cancer (small cell)
