Cancer Flashcards
What are tumour suppressor genes?
genes that produce proteins to slow cell division and cause cell death if DNA copying errors are detected
What happens if a mutation occurs in tumour suppressor genes?
cell division will continue and mutated cells will not be detected and destroyed, cell division increases
What is hypermethylation?
increased number of methyl groups added
How might hypermethylation impact tumour suppressor genes?
cause them to tightly coil so would not be expressed (so it will not control mitosis or cause cell death)
What is hypomethylation?
a decrease in the number of methyl groups added
Why might hypomethylation lead to cancer?
oncogenes are turned on continually so mitosis is happening even when it is not needed
What are proto-oncogenes?
genes that regulate the production of growth factors which stimulate cell division
What are 3 roles of tumour Suppressor Genes?
- apostasis
- ‘fix’ DNA
- stop/reduce cell division
What happens if tumour suppressor genes are mutated?
cell division increases due to less regulation
What are mutated proto-oncogenes called?
oncogenes
What are 2 ways that oncogenes cause increased cell division?
- increase the amount of growth factor produced
- stimulate growth factor receptors even when no growth factor is present
How are malignant tumours different from benign tumours
malignant:
- grow fastER
- metastasise as no adhesion molecules produced
- are not surrounded by a capsule so grow into surrounding tissues
- more likely to be life-threatening
- often have systemic effects
What is the role of adhesion molecules produced by benign tumours?
makes cells stick together so tumours do not metastasise
How do tumours metastasise?
- develop blood and lymph vessels in vascularisation
- tumour cells enter blood or lymph vessels
- tumour cells circulate in blood/lymph
- tumour cells adhere to blood vessel walls, squeeze out and invade other tissues
- tumours also form in lymph nodes
How does hypermethylation of tumour suppressor genes cause cancer?
- hypermethylation in promoter region of TSG
- TSG inactivated
- transcription inhibited
- increased, uncontrolled cell division