Week 12 Flashcards
Cancer Genetics
how is the mortality of cancer changing over time
it is decreasing
how is the incidence of cancer changing over time
it is not changing
is cancer inherited
no, but certain inherited mutations can predispose one to cancer
define: oncogenesis
process by which normal cells transform into cancerous cells
how does cancer begin
loss of cell cycle control forming a tumour
what are the 4 types of cancer
- carcinoma
- sarcoma
- leukemia
- lymphoma
define: carcinoma
cancer of epithelial origin
define: sarcoma
cancer of connective tissue
define: leukemia
cancer of blood-forming tissue
define: lymphoma
cancer of cells of the immune system
what are examples of tumor suppressor genes
p53 and RB
what is cyclin-dependent kinase (CDK) regulated by
cyclin
what does the CDK regulated by cyclin D normally bind to
the start checkpoint
what does p53 regulate in mammals
G1 to S checkpoint
what is the function of p53
transcription factor that induces expression of p21
what does p21 do
inactivates CDK, stops movement into S phase
at what point does apoptosis occur in relation to p53
when p53 concentration increases to a certain level
do mutations of p53 act dominantly or recessively
recessively
what percentage of all cancers are associated with mutations in p53
~50%
what does RB regulate
G1 to S checkpoint
what is the function of the protein product RB
controls the cell cycle
what happens in the absence of function RB
S phase cannot be stopped, results in uncontrolled cell growth
how does inheritance play into retinoblastoma
inheritance of one copy of the RB allele predisposes individuals to cancer of the retina
define: sporadic (in terms of retinoblastoma)
requires two independent mutations of RB to begin oncogenesis, child inherits normal alleles
why is the RB mutation considered autosomal dominant
there exists a strong likelihood that another mutation in the normal allele will eventually occur
define: oncogenes
mutant alleles that act dominantly to stimulate proliferation
how do telomerase genes play into cancer
normally the shortening of telomeres prevents uncontrolled replication, but there are mutations in genes controlling telomerase expression
how does cancer develop over time
thought to arise by successive mutations in a clone of proliferating cells
what is an example of a DNA virus that carries oncogenes
human papilloma virus strains 16 and 18
what percentage of cervical cancer is women is associated with HPV strains 16 and 18
> 90%
do cancer cells show loss of cell-cell communication
yes, they don’t stop even if they make contact with other cells
what is autocrine stimulation
form of cell signalling in which a cell produces signalling molecules which bind to receptors on its own surface
are gap junctions present in cancer cells
no
define: metastasis
disruption of local tissue (basement membrane) and invasion into distant tissues
define: angiogenesis
stimulate growth of blood capillaries
