Oncogenes Flashcards
what is an oncogene
it has the potential to cause malignant neoplastic growth as a result of altered form of the genes
what is an unaltered form of an oncogene called
proto-oncogene
what cellular processes are photo-oncogenes often involved in
cell division, proliferation, differentiation and apoptosis
how does Ras become oncogenic (H-Ras)
mutation localised to the 12th codon and is a G to T mutation resulting in a glycine to valine substitution mutation. this prevents binding of GAP which is responsible for Ras inactivation (Through GTP exchange for GDP) so Ras is permanently switched on
how does FGFR become oncogenic
mutations in the kinase domain activate it by mimicking the effects of phosphorylation
how can EGFR become oncogenic
through gene amplification resulting in a higher possibility of monomers colliding and so dimerising etc. resulting in aberrant ligand independent signalling. alternatively truncation removing the extracellular domain can lead to ligand independent signalling
how does c-myc become oncogenic
it can be made oncogenic through viral infection (v-myc from AMV), amplification (n-myc) and translocation (bursts lymphoma)
what is c-myc
it is a transcription factor which is involved in expression of many genes associated with the cell cycle
what is CML
a haematological cancer
what is the cause of CML
a short chromosome 22 (philidelphia chromosome) and a longer chromosome 9 as a result of translocation between these of a gene that encodes a tyrosine kinase called c-Abl which results in unregulated signalling from able kinase
what is synthetic lethality
oncogenes confer dependence on other genes for survival e.g. K-Ras mutant cells are dependent on GATA2 transcription factor so GATA2 KOs will die
