Neoplasia 3&4 The "how" Flashcards
What are some requirments of carcinogenesis?
- Self-sufficiency in growth signals
- Insensitivity to growth-inhibitory signals
- Altered cellular metabolism
- Evasion of apoptosis
- Limitless replicative potential
- Sustained angiogenesis
- Ability to invade/ metastasize
- Ability to evade host immune response
How do neoplastic cells become “immortal”?
(3)
- Autocrine growth stimulation
- Reduced apoptosis
- Telomerase
What is a tumour suppressor gene?
- Genes which inhibit neoplastic growth (under normal conditions)
- Caretaker genes
- Gatekeeper genes
e.g TP53 which encodes for p53 protein
What functions does p53 have?
Both caretaker and gatekeeper functions
How does p53 lose function?
Mutations
Missence, Nonsence
What are oncogenes?
Genes which drive the neoplastic behaviour of cells
What do oncogenes produce?
Oncoproteins
What are the five groups of oncogenes/oncoproteins?
- Growth factors
- Receptors for growth factors
- DNA binding transcription factors
- Signalling mediator with tyrosine kinase activity
- Signalling mediator with nucleotide binding activity
What does “diploid” mean?
Normal amount of DNA, two copies of each chromosome
What does “polyploidy” mean?
When cell contains exact multiples of DNA
What does “Aneuploidy” mean?
When the cell contains inexact multiples of DNA
Define “carcinogen”
An environmental agent which participates in causing tumours
How are carcinogens identified?
(5)
- Epidemiological studies
- Occupational risks
- Direct evidence
- Experimental testing
- Cell culture, animal testing
Give an example of a chemical carcinogen acting directly
Polycyclic aromatic hydrocarbons
Give an example of a carcinogen acting indirectly
The conversion of dietary nitrates into nitosamines by GI bacteria
