L09-Tumour suppressor genes cont. Flashcards
What is microsatellite instability and what is the result of this?
Microsatellites are repeated sequences of DNA that can become instable through mutations. These mutations lead to the microsatellites becoming abnormally long or short. This can lead to alterations or inactivation of TSGs.
How do highly microsatellite unstable (MSI-H) cancers tend to arise?
Through diploid new somatic mutations occuring, this is often as a consequence of epigenetic silencing.
What is the Wnt-B signalling pathway and how does it work?
B-catenin is a cytosolic signalling protein that is degraded by APC. The Wnt molecule can bind to the cell and result in inhibition of the activity of APC. This causes a build up of beta-catenin in the cell that trans-locates to the nucleus and upregulates target genes that stimulate proliferation. This is done through myc activation that promotes s-phase entry.
What is the TGF-B signalling pathway and what is this for?
TGF-B stands for transforming growth factor beta and is important in regulating growth and apoptosis. It binds to cell surface receptors TGFBR1, 2 or 3. In 2 somatic mutations most likely occur.
What are the two main activating pathways for cell proliferation?
The mitogen activating protein kinase pathway.
PI3K pathway
Which staging systems can be used to classify tumours based on their behaviour?
TNM system or dukes staging system
How can tumours be described histogenically?
Can be described according to its tissue of origin e.g. mesenchymal or epithelial
Can be described according to level of differentiation e.g. well or poorly differentiated.
What are anaplastic tumours?
When they are so poorly differentiated that they cannot be graded on differentiation.
What are teratomas?
Form from embryonic totipotent germ line cells e.g. most commonly from testis or ovaries.
