Cancer Epigentics

Question 1

What is epigenetic?

Answer 1

A gene or chromosome is temporarily modified

There is a change in gene expression and function of DNA or RNA without changing the sequence

Question 2

What are the 2 types of changes?

Answer 2

Stable - pass on to the next generation
Dynamic - response to environmental stimuli

Changes are not permanent

Question 3

When can these changes occur? 

Answer 3

During:
• Oogenesis
• spermatogenesis
• early stages of embryonic development

Question 4

Where can Epigenetic regulation occur?

Answer 4

• chromosome inactivation
• genomic imprinting
- non-Mendelian inheritance
• imprinting & DNA methylation

Question 5

Are Barr bodys formed from active or inactive chromosomes?

Answer 5

Inactive

Question 6

Phenotype | sex chromosome| Barr bodies

Answer 6

• female - XX - 1
• male - XY - 0
• Turner syndrome (f) - X0 - 0
• Triple X syndrome (f) - XXX - 2
• Klinefelter syndrome (m) - XXY - 1

Question 7

Is genomic imprinting permanent in stoma cells ?

Answer 7

Yes, but the marking of alleles can be changed from generation to another

Question 8

Where is the methyl group added in DNA Methylation?

Answer 8

CH3 is added to cytosine in DNA

This takes places in sperm or oocytes NOT both

Question 9

What models are used for Epigenetic research?

Answer 9

• Budding yeast
• protozoan
• drosophila
• arabidopsis
• Mice

Question 10

Epigenetic - key in?

Answer 10

• genetic imprinting
• development of stem cells
• X-chromosome inactivation
• differentiation in somatic cells

Question 11

FDA Epigenetic chemotherapy approved?

Answer 11

• azacytidine - lung cancer
• decitabine - leukaemia
• vorinostat - t-cell lymphoma
• romidepsin - peripheral t-cell lymphoma

Question 12

What is carcinogenesis?

Answer 12

Molecular process where cancer developed
• damage to DNA
• multiple mutations are required

Question 13

Genotoxins?

Answer 13

Cause Irreversible genetic damage
E.g: UV light (non-chemical)

Question 14

Which agent causes cancer ?

Answer 14

Carcinogens

Question 15

What are the stages in Carcinogenesis? 

Answer 15

Initiation
promotion
progression

Question 16

What occurs during initiation?

Answer 16

• carcinogen interacts with DNA - damaging the gene responsible for cell growth
• cells have repair mechanisms- is this doesnt occur cells turn into cancer
• first stage of neoplastic development

Question 17

What occurs during promotion? 

Answer 17

• cells divide - forming benign toumor
• reversible
• a promoter is not carcinogenic

Question 18

What happens during progression

Answer 18

• cells become cancerous
• irreversible
• more to tumour cells than normal
• neoplastic cells are born

Question 19

Role of tumour suppressor gene?

Answer 19

• when inactivated + oncogenes are activated = cancer can occur
• linked to normal cell activity: cell growth
• produce proteins - inhibit cell reproduction at inappropriate growth times

Question 20

Oncogenes MOA?

Answer 20

• cell surface receptors
• intracellular signal transduction pathways
• DNA-binding nuclear protein
• cell cycle proteins
• inhibitors of apoptosis

Question 21

What is the name of the most common suppressor gene ?

Answer 21

P53

Question 22

Stages of colon carcinogenesis?

Answer 22

1. Mutation of the ACP
2. DCC (deletion in colon cancer gene)
3. Changes in p53 genes
4. DNA instability

Question 23

What are tumour markers produced from ?

Answer 23

Normal or cancerous cells (a protein)

Question 24

How can tumour markers be detected?

Answer 24

• urine
• blood
• stool
• tissue

Question 25

TM Advantages?

Answer 25

• highly sensitive + specific for early detection
• can manage some cancers
• can identify stage of cancer (so treatment needed)
• can see whether tumour is responding to treatment or not

Question 26

TM Disadvantages?

Answer 26

• in non-cancerous conditions, tumour marker can increase
• have not been identified for all cancers

Question 27

Examples of TM?

Answer 27

• alpha-fetoprotein (AFP)
• beta-2-microglobin (B2M)
• beta-hCG