L45 Cancer Genetics Flashcards
Define ‘truncated’.
To shorten something by chopping off the top or bottom.
e.g. a nonsense mutation results in a truncated protein.
Amplification of the ERBB2 (HER2) oncogene can result in what cancer?
Breast, ovarian, gastric, NSCL, colon
Amplification of the MYCN oncogene can lead to what cancer?
Neuroblastoma
Point mutation in the HRAS gene can lead to what cancer?
Bladder, lung, colon, melanoma
Point mutation in the KIT oncogene can lead to what cancer?
GI stromal tumours, mastocytosis
Chromosomal rearrangement of BCR-ABL1 oncogene can lead to what cancer?
Chronic myeloid leukaemia (CML)
True or false: Loss of fnction in tumour suppressor genes require 2 mutations (both alleles) as the mutation is recessive to the wild type
True.
Conversely, oncogenes only require 1 change as the mutant is dominant to the WT, and results in gain of function.
True or false: Oncogenes trigger cell transformation
True
How do proto-oncogenes become activated oncogenes?
Via gain of function events. Activation by:
- amplification
- mutation
- chromosomal rearrangement
Her-2 is an oncogene associated with 30% of breast cancers. What effect does amplification of Her-2 have?
Cell becomes hyper-responsive to growth signals.
Trastuzumab (Herceptin) is a treatment for what?
Her2+ cancers
Ras is an oncogene associated with a third of all human cancers. What type of protein is influenced by Ras mutations?
Signal transducer proteins.
Normally transducer proteins have active and inactive forms. Mutations in Ras make it constitutively active.
What drug is used to target vascular endothelial growth factor (VEGF)?
Bevacizumab (avastin)
Slows the growth of new blood vessels.
When in the cell cycle do tumour suppressor genes work?
Check points (G1/S, G2/M)
Gatekeepers, caretakers, and landscapers are classifications for what?
Tumour suppressors
What type of gene is the Rb (retinoblastoma) gene?
Tumour suppressor
1 faulty copy can be inherited and the other allele can be lost later in life. Causes retinoblastoma in children.
True or false: Mutations in tumour suppressor genes are generally recessive. Both alleles must be mutated (inactive) in order for the gene to stop functioning (since wild type function is dominant )
True
p53 is an example of what type of gene?
Tumour suppressor gene.
Normally needed for apoptosis.
Protects genome by initiating DNA repair or apoptosis.
Tumour viral proteins usually target which gene products?
p53 and Rb tumour suppressors
Tumour-suppressor genes prevent __1__, they are deactivated in cancer by __2__ mutations in both alleles of the gene
1) uncontrolled cell division
2) recessive
