Chapter Four Flashcards
What is common between oncogenes from human tumor cells by transfection experiments & oncogenes from transforming retroviruses?
both derive from same group of preexisting normal cellular genes
Can cancers be triggered by the activation of endogenous retroviruses?
yes:
induced by chemical agents
induced by infectious agents
What is a retrovirus?
any of a group of RNA viruses which insert a DNA copy of their genome into the host cell in order to replicate
What is an endogenous retrovirus?
endogenous viral elements in the genome that closely resemble and can be derived from retroviruses
How are oncogenes activated?
regulatory & structural
mutations
amplification
chromosome rearrangements
How does gene amplification occur?
preferential replication of a segment (amplicon) of chromosomal DNA
What is translocation & how does it impact cells?
fusion of region of one chromosome to a nonhomologous chromosome
can result in fusion of 2 protein coding sequences leading to hybrid protein that functions differently than the two normals proteins from which it arose (ex: Bcr-Abl protein encountered in chronic myelogenous leukemias)
What molecular mechanisms might cause a certain region of chromosomal DNA to accidentally undergo amplification?
promoter or enhancer insertion
chromosomal translocation
How can transfection of DNA be useful?
strategy for detecting nonviral oncogenes
can arise fro mechanisms with no apparent connection with viral infection
What are oncogenes discovered in human tumor cell lines related to?
genes carried by transformed retroviruses
activated by retroviruses & nonviral mutagens
What additional 3 mechanisms can myc oncogenes arise from?
- amplification
- translocation
- involvement of miRNA
How can structural changes in protein lead to oncogene activation?
deregulated firing of GF receptors
