genes and cancer Flashcards
1
Q
how are cancers induced
A
by mutations in cancer-causing genes
- majority in acquired or somatic
- some mutations may be inherited
2
Q
genes which cause cancers
A
- oncogenes
(dominant acting, promote cell growth) - tumour suppressor genes
(loss of activity, inhibit cell proliferation) - genes involved in regulation of apoptosis
also epigenetics, DNA repair gene abnormalities
3
Q
oncogenes
A
in their normal state = proto-oncogenes
if activated e.g. mutation, become an oncogene
- activation results in a gain of function
4
Q
function of an oncogene (what it codes for)
A
mostly signal transduction code for: - growth factors - growth factor receptor - intracellular signal transduction - nuclear transcription factor
5
Q
activation of oncogenes
A
- gene amplification e.g. increased copy no.
- over expression of the gene
- point mutations in the oncogene
- chromosome translocation
- epigenetic mechanisms
6
Q
HER-2
A
- proto-oncogene
- encodes for growth factor receptor in mammary glands
- amplification of this gene results in overexpression and can lead to breast cancer
7
Q
how do chromosomal translocations activate proto-oncogenes?
A
- by moving adjacent to a promoter region or actively transcribed gene
or
- brings genes together that makes novel protein resulting in increased activity e.g. proliferation of cell
8
Q
lymphoma
A
a malignant tumour arising out of B or T cells
- present with enlarged lymph nodes
9
Q
tumour suppressor genes
A
- anti-oncogenes
- ‘brakes’ of normal cell growth
- requires the loss of activity of both alleles e.g. inactivation of both alleles is required to loose function
10
Q
genes which affect apoptosis
A
- the upregulation of genes that encode for proteins that block apoptosis
- loss of activity of genes which encode for proteins that mediate apoptosis e.g. p53
11
Q
chronic myeloid leukemia
A
- acquired chromosomal translocation
- Philadelphia gene
- results in proto-oncogene activation
- uncontrolled cell proliferation
- targetted cancer therapy
