MoD Neoplasia 3- Why And How Do Neoplasms Occur? Flashcards
What are intrinsic (3) and extrinsic (2) factors of cancer formation?
Intrinsic- age, gender, heredity
Extrinsic- environment, lifestyle
What are 5 risk factors of cancer?
High BMI Low fruit and veg consumption Low exercise levels Tobacco Alcohol
What are the three catergories of extrinsic carcinogens?
Chemicals, radiation, infections
What is this name of a chemical used in the dye industry? What has it showed us? (3)
2-napthylamine
- That there is a long delay between carcinogen exposure and malignant neoplasm
- Cancer risk depends on carcinogen dosage
- Can be organ specificity for carcinogens
What are initiators and promoters? What do they cause?
Initiators- mutagens
Promotors- cause prolonged proliferation.
They produce a monoclonal expansion of mutant cells.
How do procarcinogens become carcinogens?
In the liver using cytochrome P450.
What are complete carcinogens?
Carcinogens that act as promoters and initiatiors.
What is radiation?
Any type of energy that travels through space.
What two things does direct radiation damage cause?
- altered bases
- single and double strand DNA breaks
What does indirect radiation damage cause?
Free radical production.
How can infections causes mutations? (2)
- can affect genes that control cell growth
- can cause chronic tissue injury which therefore causes mutations
What cancer is HPV associated with?
Cervical
How does HPV cause carcinoma development? (2)
It expresses E6 and E7 proteins which inhibits P53 and pRB respectively. This means that DNA damage can’t be detected and either repaired, or gotten rid of by apoptosis, and cell are checked at restriction points in the cell cycle before continuing.
What inheritance pattern does retinoblastoma have?
Dominant
What is the two hit hypothesis?
The idea that familial cancers have a germ line ‘hit’ which affects all cells in the body, followed by a somatic ‘hit’ which mutates one of these already hit cells.
Where as sporadic carcinomas require 2 hits somatically, as they don’t have a genetic inheritance. For cancer to arise, the hits must be to the same cell.
What is the normal function of tumour suppressor genes?
Inhibit neoplastic growth.
How are tumour suppressor genes inactivated?
By 2 mutations- one to each allele.
How do oncogenes arise from proto-oncogenes?
Abnormal activation of one proto-oncogene allele.
What are the proto-oncogenes and tumour suppressor genes that have to be activated/inactivated to cause cells to move pass the restriction point continuously in the cell cycle?
Proto-oncogene- RAS
Tumour suppressor gene- RB gene.
What is xeroderma pigmentosum?
A rare hereditary defect in the enzymes that repair DNA after damage by UV Rays. It leads to an increased sensitivity to UV, which means they have a tendency to develop skin cancer at an early age.
What is the role of BRCA 1/2?
Repair single and double strand DNA breaks
What is genetic instability?
An accelerated mutation rate.
What are caretaker genes?
Tumour suppressor genes that maintain genetic stability.
What is progression?
Multiple mutations in malignant neoplasms.
What are the three steps of cancer formation?
Initiation, promotion, progression
What are the 6 hallmarks of cancer? What causes them?
- Self sufficiency in growth signals
- Ability to resist stop growth signals
- Cell immortalisation
- Sustained angiogenesis ability
- Resistance to apoptosis
- Ability to invade and metastasis.
Mutations
What is carcinogenesis?
The causes of cancer
