Lecture 31

Question 1

What causes tumours to form

Answer 1

Tumours are created by cells that have lost the ability to assemble and create tissue of normal form and function

Question 2

The plasias occur independently of each other and in a sequential manner, T or F

Answer 2

F – plasia’s often occur together or can develop over time

Question 3

What is the overall trend of cancer progression

Answer 3

Hyperplasia –> Metaplasia –> Dysplasia –> Neoplasia

Question 4

What is the major risk factor in acquiring cancer

Answer 4

Age – on average the older you are, the higher your risk of cancer

Question 5

The likelihood of developing cancer increases in with age for every cancer, T or F

Answer 5

F – the age/incidence prolife varies with different cancer – for example testicular cancer reaches its peak incidence during puberty and adolescence

Question 6

The incidence of cancer is increasing, T or F

Answer 6

T – 80% of patients that die of other causes will be found to have a tumour too

Question 7

Explain the results of the Japanese/Hawaii migrant studies in explaining the environmental influence in cancer influence

Answer 7

Amongst Japanese nationals living in Japan, stomach and liver cancer levels were elevated. After moving to Hawaii though, the rates of both stomach and liver cancer decreased. However the levels of colon and prostate cancer in these migrants did see an increase towards the higher levels seen in Caucasian Hawaiians. This shows that migrants acquire a cancer spectrum depending on their environment not just their genetic heritage

Question 8

Explain Richard Doll’s contribution to cancer research

Answer 8

Doll linked the carcinomas of the lung to smoking. He was deemed the father of epidemiology for correlating of the number of cigarettes smoked to the incidence of lung cancers. He also identified the lag phase after taking up smoking due to the time taken for the induction of genetic instability

Question 9

How long is the lag phase after taking up smoking before lung carcinomas usually begin to present

Answer 9

20 years

Question 10

Give examples of cancers that have a genetic or familiar basis of inheritance

Answer 10

Colon cancer – FAP/APC, Retinoblastoma, Kidney Cancer – Wilms’ Tumour, Breast Cancer – Hereditary (BRCA1/2)

Question 11

A single mutation is enough to cause cancer, T or F

Answer 11

F

Question 12

What is the equation that links the probability of tumorigenesis with the number of mutations and age

Answer 12

LogP(T)=nLogA+k where P(T) is the probability of a tumour forming, n is the slope or the number of mutations required, A is age and k represents a constant

Question 13

Which residues do cdks phosphorylate in target proteins

Answer 13

Serine/Threonine

Question 14

What prevents the inactive cdks from acting

Answer 14

Their active site is occluded by the T loop

Question 15

What happens in response to cyclin binding to cdk and the subsequent activation of the kinase

Answer 15

Cyclin binding to Cdk pulls the T loop away from the active site and exposes the bound ATP which allows it to access to target proteins and phosphorylate them

Question 16

What other protein is required for the full activation of cdk and why is this

Answer 16

Cdk activating kinase phosphorylates a crucial threonine in the T loop of the protein. This enables cdk to bind and phosphorylate its target proteins

Question 17

What is the role of cdk inhibitor proteins (CKIs)

Answer 17

Cdk inhibitor proteins (CKIs) help regulate the rise and fall of cyclin-Cdk activity. Some inhibitors bind directly at the kinase active site and block kinase activity by interfering with ATP binding