Cancer module 1- Oncogenes and differentiation Flashcards
What is the name for tumours that originate from only one mutated cell?
These tumours are called ‘clonal’ tumours.
What is a loss of differentiation with regards to a cancer cell?
Normally cells will proliferate and then differentiate, meaning that they specialise into the distinct parenchymal cell type that they were destined to be. Cancer cells often contain mutations so that they are stuck in the proliferative phase and they never specialise.
Loss of differentiation= loss of capacity to specialise
what percentage of cancers are due to genetic predisposition?
5-10%
what percentage of cancers are sporadic (random)?
90-95%
What is an oncogene?
An oncogene is a normal gene that encodes for an aspect of normal cell proliferation. These genes are often mutated, or manipulated by cancer viruses to form cancer cells.
Name two molecule families that are converted into oncogenes during cancer.
Tyrosine Kinases- these cells enable phosphorylation of domains that trigger proliferation of the cell.
Transcription factors- these factors bind to promotor regions on genes and begin mRNA production in cell proliferation.
What is a retrovirus?
A family of viruses that have its genome in RNA form and uses reverse transcriptases to convert its genome into DNA form, so it can incorporate its own genome into the DNA genome of its human host.
what is an acutely transforming virus?
This is a type of virus that contains a viral oncogene. An example would be the Rous sarcoma virus which contains the v-src, or sarcoma gene that is a mutated version of the human c-src proto-oncogene. These viruses use the v-src gene to convert a healthy cell into a cancer cell.
Does the location of the mutation within one pathway correspond to a different cancer being produced?
No. Provided the pathway is the same one, it doesn’t matter which part of it is mutated, they will all result in the same cancer type being produced.
Mutant p53 is an example of what type of oncogene?
A transcription factor oncogene.
High Myb expression is a feature of which 2 cancer types?
Breast and colorectal cancers. High myb expression is also correlated with low cancer survival.
What does the Myb proto-oncogene normally do in breast tissue?
The Myb gene is normally responsible for normal mammary gland cell proliferation and mammary gland development in general.
