1 - Oncogenes and tumour suppressors Flashcards
Constitutively active:
always, permanently active, doesn’t need a signalling pathway to be activated.
Knudson two hit hypothesis:
This refers to the requirement of the loss / loss of function mutation of both tumour suppressor gene alleles for cancer to develop i.e. the alleles need two hits.
Oncogenes:
Mutated (Gain of function) or overexpressed forms of proto-oncogenes that encode proteins that stimulate uncontrolled proliferation or promote cell survival by either being constitutively active or overexpressed.
Oncoprotein:
Protein encoded by oncogene. They are normally regulatory proteins in proliferative signalling pathways and the cell cycle, as well as anti-apoptotic proteins in the apoptotic pathway. When overactive or over expressed, they cause a cell to become a cancer cell.
Overexpressed gene:
A gene that is transcribed more than it should be which results in an increased amount of encoded normal protein.
Overexpressed protein:
Too much protein is made because the gene encoding it is over transcribed or the protein is not degraded when it should be.
Proto-oncogenes or cellular oncogenes:
genes that encode cellular proteins that regulate normal cell proliferation and survival.
Translocation:
a chromosomal translocation is a chromosome abnormality caused by rearrangement of parts between non homologous chromosomes. A gene fusion may be created when the translocation joins two otherwise separated genes.
Tumour Suppressor gene:
These are genes that encode proteins that normally suppress cell proliferation and promote cell death. When these genes are mutated to cause a loss or reduction in their encoded protein’s function (loss of function mutation), cellular proliferation is not inhibited or apoptosis activated and the cell can progress to cancer.
Tumour suppressor:
Protein encoded by tumour suppressor gene which downregulates cell proliferation, activates DNA repair and promotes cell death.
