Flashcards in Introduction to Cancer 2 Deck (36)
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1
What are the 6 hallmarks of cancer ?
1) Sustaining proliferative signalling
2) Evading growth suppressors= ignore the other cells and continue to grow
3) Activating invasion and metastasis= metastasis complicates the function of the organ
4) Enabling replicative immortality= ignoring any mechanisms initiating death
5) Inducing angiogenesis= fundamental for tumours to grow
6) Resisting cell death
2
What is cancer and what does it require?
COLLECTION of related diseases- tumours go through many of the same processes
They can start from almost any cell type
They require multiple mutations and undergo uncontrolled cell division
It is a step-wise process and can damage surrouding organs which is a key issue of the disease. They can also sometime metastasise.
3
In breast tissue what is the most common cell type to develop cancer?
the epithelial cells within the ducts
4
Where else in breast tissue can tumours occur ?
Within the lobules and stroma
5
Why is breast tissue prone to tumourogenesis?
because it is very sensitive to hormonal changes
6
What is the difference between ductal carcinoma and invasive ductal carcinoma?
ductal carcinoma= it is cancer but it is retained within the basement membrane and an operation is relatively easy because the tumour can be removed
invasive ductal carcinoma= the tumour cells break through the basement membrane and this allows them to metastasise.
7
What are the different ways of classifying cancers?
Malignant/benign= any malignant tumour left from surgery will continue to grow leading to relapse
Pathology/histological subtype
- receptor status
Grade= level of differentiation- the more undifferentiated the worse the tumour is
Stage
- size
- spread= confined or spreading throughout the body
Molecular= gene expression- the level of improvement for treatment based on this is limited
8
What are the receptor status' in breast cancer?
It is one of the most important ways to classify breast cancer
estrogen receptor= use hormone eblation therapy such as tamoxifen or aromatase inhibitors to block the production of estrogen
progesterone receptors are also important
9
What is the link between Her2/ErbB2 in breast cancer?
this is a signalling molecule which can change its gene transcription
Perceptin- monoclonal antibody that stops this molecule being activated by its ligand
10
What happens to breast cancer patients that are triple negative?
They dont demonstrate any pathological/histological references, so they are given a horrible concoction of cytotoxic chemotherapeutic drugs
11
What is a mutation ?
it is a changes in DNA- causes changes it how genes behave and their physiology
12
Why are mutations very important ?
They are essential for evolution- they are the raw material of genetic variation
13
What are the types of bases ?
Pyrimidines= cytosine, thymine and uracil
Purines= adenine and guanine
14
What is nearly always true about mutations?
They originate in DNA but their effects are shown through proteins - it is chemical modifications that cause changes to DNA
15
How many mutations occur per day ?
In every cell about 100 mutations occur in the body per day - most of them dont matter
16
What are the different types of mutations?
deletions, insertions and point mutations
Synonymous= made a change to codon but no change to amino acid
Non-synonymous= change in the codon which causes a change in the amino acid
- non-sense= truncating the protein early
-missense= substituting an aa for another one
chromosome rearrangment- often occurs in leukemias
copy number variants- Her2- entire gene is duplicated more
epigenetic mutation- ER alpha- not all mutations occur in DNA
17
What are the different mechanisms of mutations?
Spontaneous chromosome re-arrangment
Gene amplification
Random errors in replication= mistakes when DNA is replicated
Inheritance- common mutations e.g. brac-2 in breast cancer is highly inherited
Viruses- this was how oncogenes were first discovered
Environmental exposure- chemical mutagens and radiation
18
What are some causes of mutations ?
OXIDATIVE DAMAGE of DNA by ROS
- hydrogen perioxide, hydroxyl radicals and superoxide radicals
These ROS can arise from irradiation or they can be produced by aerobic metabolism
Environmental chemicals
- chemicals present in tobacco
- product of industrial activity
- resulting from metabolism of food components
-cooking food- way food is prepared
19
What are the 2 types of genomic DNA cells contain?
either contain 1 set of genomic DNA= germ cells
or they contain 2 sets of genomic DNA= regular diploid cells
20
what can defects and ineffiences in DNA repair systems lead to ?
it can increase the number of mutations
21
How effective are DNA repair systems ?
due to DNA repair systems, less than 1 incident of DNA damage in 1000 hits becomes a mutation
if mutations occur in the repair systems then this is very bad- causes cells to be prone to developing lots of mutations
22
What is the base-excision repair system ?
this cuts out the entire base
types of damage: basic sites, free radical oxidation or deamination of cytosine/methylcytosine
23
What is base mis-match repair?
notices irregular DNA so it replaces the base
types of damage: small adducts, free ROS, insertions/deletions
24
What is the nucleotide excision repair?
replace sugar aswell
types of damage: large adducts and UV cross links
25
What is alkyl transferase?
it is an enzymes
types of damage: small alkyl adducts
26
What is homologous recombination?
this only occurs in homologous recombination
types of damage: strand breaks
27
What happens if mutations are not repaired?
then there is an increased risk of cancer - it is proportional to mutation rate
28
What are the 3 classes of genes frequently mutated in cancer ?
PROTO-ONCOGENES= they can become mutated forming oncogenes. Normally they are important in making cells divide and grow
TUMOUR SUPPRESSOR GENES- these stop genes dividing
GENES LINKED TO MUTATION RATE
29
Define oncogene:
gene that has the potential to cause cancer
30
