What is cancer?
Uncontrolled cell division that can invade other tissue and impede their function
What is a tumour?
Any swelling Can be benign or malignant
What is a neoplasm?
New growth not in response to any stimulus
Metastatic potential is present This involves any neoplasm invading the basement membrane
What is metastasis?
The spreading of a neoplasm to a different part of the body
Give three pre-malignant stages
- Dysplasia - disordered growth with no stimulus (no invasion of basement membrane)
- Metaplasia - change of one cell type to another
- Hyperplasia - increase in cell number
Metaplasia is a response to _____
What can initiate metaplasia?
- Injurious or noxious stimuli
- Cytokines and cell signals
Why are post-menopausal obese women at risk to hyperplasia (and cancer)?
Oestrogen will cause proliferation of the endometrium as part of the menstrual cycle. Cholesterol is similar in structure to oestrogen Obese women have high cholesterol which can cause proliferation in the endometrium Due to increased (an unnecessary) proliferations, these women have more "chances" for cells to begin to grown autonomously and for hyperplasia to occur
What occurs in dysplasia that does not occur in either metaplasia or hyperplasia?
A genetic abnormality is developed
What is carcinoma in-situ?
This is the final stage a neoplasm goes through before becoming malignant (invading basement membrane and spreading by metastases) This is the same as high-grade dysplasia
How is the N:C (nuclear:cytoplasmic) ratio affected in malignant cells affected?
N:C ratio is high
List some causes of cancer
- UV radiation, and other rdiation types
- Burnt toast...supposedly Etc.
What are Weinberg Hallmarks?
These are "bad decisions" made by a cell that are key to becoming malignant.
- Increased growth signals
- Growth suppression removed
- Avoiding apoptosis
- Achieving immortality
- Becoming invasive
- Making own blood supply (angiogenesis)
- Lose cellular DNA spellchecking
What is Li-Fraumeni syndrome?
Genetic condition affecting the tp53 gene which codes for p53. This means sufferers from LFS are unable to stop excessive growth and attempt DNA repairs (or activate apoptosis)
How does radiation cause cancer
Pyrimidine dimers are formed in DNA which are molecular lesions involving two consecutive bases on a single DNA strand to bind together ruining the normal base pairing Numerous instances can cause repair mechanisms to become overwhelmed
Describe briefly the cell cycle
- Cyclin D activated CDK4 (cyclin dependent kinase)
- CDK4 phosphorylates Rb (retinoblastoma)
- Rb now unbinds from DNA allowing for DNA replication to occur - access to DNA is now possible
- Synthesis phase now occurs involving DNA replication
- M phase follows after G2 and the cell divides
- Cytokinesis is when the cell physically divided
What are oncogenes?
A gene with the potential to cause cancer It involves increased growth
What are tumour supressors?
These are genes preventing the pathway to cancer
How can neoplastic cells evade DNA spellchecking?
Destroying spellcheck proteins such as P53
What happens to a tumour in the bloodstream?
It will aggregate with platelets This means it will eventually slow down and stop within a blood vessel and grow in this new location
Name 2 growth factors that can aid angiogenesis (for neoplasms)
- VEGF (vascular endothelial growth factor)
- PDGF (platelet derived growth factor)
What are the three stages involved in the pathway of mutations and neoplasm development?
- Initiation - first mutation
- Promotion - accumulation of mutations (dysplasia)
- Persistance - malignant
FISH is better than PCR for _____ genetic abnormalities
PCR is ideal for _____ genetic abnormalites
What are the functions of p53? (4)
- Cell cycle arrest at G1
- Increase levels of p21 to inhibit CDKs preventing Rb phosphorylation and hence DNA replication
- Apoptosis activation when damage is too great
- Activate repair mechanisms when damage is minimal
What are first principles in relation to identifying neoplasms?
These are quick decisions that can make an estimate as to whether the neoplasm appears malignant or not
How do benign tumour look?
- round and smooth
- Normal N:C ratio
- Slow growth
How do malignant tumours look?
- Not symmetrical
- jagged edges
- High N:C ratio
- Fast growth
What is differentiation?
The process by which stem cells develop into mature cells types