Cancer Flashcards
Define oncogenesis/ tumourogenesis
Cancer forming process
What causes oncogensis?
Mutations
usually a series of mutations
Describe the growth in benign and malignant tumours
Benign- Expansive and slow
Malignant- infiltrating and rapid
Describe mitoses and evolution in benign and malignant tumours
Benign- rare but typical mitosis and local evolution
Malignant- numerous and atypical mitosis, local and generalised evolution
Can maligant tumours metastasize?
yes
What are tumours made up from?
And what is the collective name for all this?
Maligant cells
host cells
secreted factors
extracellular matrix proteins
Tumour microenvironment
What is the most common preventive cancer in the UK?
Lung
What can cause mutations?
Name 3 things
1) Carcinogenic substances
2) Viruses trigger trasnformation of cells
3) Inheritance of certain genes
Mutations in the gene can be generated when?
Germline- originate in the gametes
Somatic- adults/infants after birth
What is the normal function of the protooncogenes?
Promotes cell survival or proliferation
What is the effect of the mutation on protooncogene’?
Is the gene dominant or recessive?
Gain of function allows unregulated cell survival and proliferation
Dominant
What is the normal function of the tumour repressor genes?
inhibits cell survival or proliferation
What is the normal function of the caretaker genes?
Repair or prevent DNA damage.
What is the effect of the mutation on tumour suppressor genes’?
Is the gene dominant or recessive?
Loss of function allows unregulated cell survival and proliferation
Recessive gene
What is the effect of the mutation on caretaker genes?
Is the gene dominant or recessive?
Loss of function allows accumulation of mutation
Recessive gene
What is the difference between the protooncogene and oncogene?
Oncogene=mutated
Describe the C-myc gene mutation and what it causes
This is a protooncogene
Usually, mRNA is short lived and protein levels are low
BUT translocation from Ch 8 to 14 causes Burkitt lymphorma
How many classes of proteins are recognised as tumour suppressor genes?
5
Name some of the roles tumour suppressor genes have
Promote apoptosis
Enzymes that participate in DNA repair
Check piont control proteins that arrest cell cycle
Which chromosome is Tumour suppressor gene p53 found on?
Chromosome 17
What is the role of p53?
Binds DNA simulating p21 protein which interacts with a cell division stimulating protein- cdk2
What is the result of a mutated p53?
No longer bind to DNA, thus p21 protein does not provide a stop signal for cell division
HENCE CELLS DIVIDE UNCONTROLABLY
What is petos paradox?
Elephants have extra copies of p53 so blood cells are highly sensitive to DNA damage, causing apoptosis of damaged cells rather than repair
What are the 2 best studied caretaker genes?
mlh1 and mlh2
What is the result of a mutation to the caretaker genes?
Mutations can increase the rate of point mutations in genes
What chromosomal mutations can tumour cells commonly have?
Aneuploidy- extra chromosomes
Translocation
Duplications
What is does LOH stand for?
Loss of Heterozygosity
-loss of functioning allele hence having an malignant phenotype
Define mutagen
A chemical or physical agent that induces a mutation, These can act in/directly
Name 2 viruses that cause cancer
Human Papilloma Virus
HTLV-1 a retroviruses
Name 3 selection pressures for cancer
o2, competition for space , blood supply
Can cancers spread through animals?
Yes eg Canine Transmissible venereal Tumour
How can cancers be spread?
Biting, sexual contact, via seawater
