8 Flashcards
Intrinsic Factors of Cancer
Age
Gender
Hereditary (Genetic)
Extrinsic Factors of Cancer
Behavioural
- High BMI
- Low Fruit n Veg
- Low Phys Activity
- Tobacco/ Alcohol
Environmental
- Chemical
- Radiation
- Viruses
How is a pro-carcinogen converted into a carcinogen?
Using cytochrome P450 in the liver
What is a complete carcinogen (+example)
One that acts as both initiator and promoter
E.g. cig smoke
How does radiation cause cancer DIRECTLY?
DNA damage
How does radiation cause cancer INDIRECTLY?
Generates free radicals
How do infections cause cancer DIRECTLY? (+example)
Affect genes that control cell growth
E.g. HPV expresses E6 prot which inhibits p53 (tumour suppressor gene)
How do infections cause cancer INDIRECTLY? (+example)
Cause chronic tissue injury resulting in regen
- Regen can act as pre-existing promoter for mutations
- Or can cause new mutations from DNA rep errors
E.g. HIV reduces immunity ➡️ allows carcinogenic infections to occur
What is the role of the RAS oncogene?
Encodes G proteins ➡️ relays signals ➡️ pushes cell past restric point
Encodes HER2 (GF receptors)
Encodes MYC (Transc factors)
What do tumour supressor genes do? (+examples)
X passage thru restric point
E.g p53 and RB
What causes genetic instability?
Chromosome segregation @ mitosis
Describe Xeroderma Pigmentosum
Mutation in 1 of 7 genes that affect DNA Nucleotide Excision Repair
Describe HNPCC (and what does it stand for?)
Hereditary Non-Polyposis Colon Cancer
- Colon carcinoma
- Mutation affects DNA mismatch repair
Describe Familial Breast Cancer
Mutation in BRCA1 / BRCA2 genes
- Genes resp for double strand DNA break repair
Describe Familial Retinoblastoma
1st Hit: Germline ➡️ Affects all body cells
2nd Hit: Somatic Mutation
What must both hits be in Sporadic Retinoblastoma?
Somatic mutations & both must occur on SAME cell
No germline mut
What is initiation?
First carcinogenesis stage
Mutation caused by carcinogen
What is promotion?
Second carcinogenesis stage
Cell prolif ➡️ mutated cell gen
No mutation
What is progression?
Third carcinogenesis stage
Transformation of benign tumour ➡️ neoplasms & malignancy
Karyotypic change (xsome number change)
Adenoma-Carcinoma sequence occurs
What is the Adenoma-Carcinoma Sequence?
When cells acquire further activated oncogenes / inactivated TS
Promotes gen instability
Adenoma ➡️ Carcinoma
What are the 6 Hallmarks of Cancer?
- Self Sufficiency In Growth Signals
- Resistant to Growth Stop Signals
- No limit to no. of times cell can divide
- Sustained angiogenesis ability
- Apoptosis resistance
- Ability to invade & prod. metastases
Which Hallmarks of Cancer are relevant to Malignant AND Benign Neoplasms?
1-5
Which Hallmarks of Cancer are relevant to Malignant Neoplasms ONLY?
6
Ability to Invade n prod metastases
What are 2 occupations assoc w tumour dev
Asbestos exposure
Dye manufacture
What are 2 medical conditions assoc w increased risk of malignancy?
Ulcerative Colitis
Cirrhosis
What are Caretaker genes?
Class of TS genes that give genetic stability
