An outline of cancer process

Question 1

What does a monoclonal cancer mean?

Answer 1

Arises from a single cell

Question 2

Which stage of the cell cycle can give rise to non-proliferating cells?

Answer 2

G1

Question 3

Describe the activity of cancer cells

Answer 3

Frequent mitosis

Increase in growth factor secretion

Loss of contact inhibition

Question 4

Describe the structure of cancer cells

Answer 4

Lots of blood vessels

Increase in oncogene expression

Loss of tumour suppressor genes

Question 5

What are the initiation causes of cancer?

Answer 5

Chemical

Physical

Viral

Question 6

Give an example of chemicals which cause cancer

Answer 6

Nitrogen mustard gas - leukaemia

Aninline dyes - bladder cancer

Alcohol and smoking - Lung, head and neck, GI

Question 7

Give an example of physical carcinogens

Answer 7

Ionising radiation - Radon source is mainly in buildings, risk increased by smoking, ventilation reduces risk

Question 8

What is the mechanism of ionising radiation to cause cancer?

Answer 8

Chromosome translocation

Gene amplification

Oncogene activation

Question 9

Give an example of Viral carcinogens

Answer 9

Papillomavirus - cervical cancer

Hepatitis B - Liver acncer

Herpes Virus - Burkitt’s lymphoma

Question 10

What are growth factors and what are their effects?

Answer 10

Polypeptide molecules

Regulate cell growth and function, bind to cell membrane receptors, stimulate activation of intracellular signal transduction pathways

Question 11

Define autocrine stimulation

Answer 11

Cell carries the receptor and secretes growth factor

Cell escapes normal control mechanism

Question 12

Define paracrine stimuation

Answer 12

GF’s are produced by local neighbour

Question 13

Describe the process of invasion and metastasis

Answer 13

Tumour invades through basement membrane

Moves into extracellular matrix/connective tissue/surrounding cellsInvades blood vessels

Tumour cells ‘arrested’ in distant organ

Question 14

What is the effect of Matrix metalloproteinases, Plasmin and Cathepsin on Invasion and metastasis?

Answer 14

Increase the likelihood of the cell coming into the extracellular matrix and metastasising

Question 15

What is the role of enzymes involved in cell adhesion (cahedrins, Integrins, CD 44) on Invasion and metastasis?

Answer 15

makes the cell less sticky so it is more likely to invade other cells

Question 16

What is the cost of angiogenesis in the maintenance and progression of tumours?

Answer 16

Degradation of the extracellular matrix - necessary for new blood vessel formation to occur

Question 17

What is the most commonly altered gene in human tumours?

Answer 17

P53 which is a tumour suppressor gene

Question 18

What is the normal function of the p53 gene?

Answer 18

Transcriptional regulator, promotes DNA repair, apoptosis, diffrerentiation

It is the G1/S checkpoint control gene

Question 19

What stimulates p53?

Answer 19

Induced by DNA damage and hypoxia

Question 20

Give an example of a growth factor

Answer 20

Vascular endothelial growth factor VEGF - leads to the growth, proliferation, migration and survival of endothelial cells

Question 21

What is the effect of Anti-VEGF?

Answer 21

Prevents the action of VEGF on receptors.

Reduces microvascular growth, inhibits the progression of metastatic disease and reduces intratumoral pressure, which may improve the delivery of cytotoxic agents.

Question 22

What is the function of the PD-1 protein?

Answer 22

Expressed on T cels and pro-B cells.

Plays an important role in down-regulating the immune system by preventing the activation of T-cells, reducing autoimmunity and promotes self-tolerance.

Question 23

What is the effect of the binding between PDL-1 (found on the surface of cells in various tissues) and PD-1?

Answer 23

Promotes immunosuppression to various mechanisms including apoptosis

Question 24

How can a PD-1 inhibitor treat cancer?

Answer 24

Prevents the binding interaction between PD-1 and PDL-1 and so activates the immune system to attack tumours

Question 25

How does the presence of PDL-1 in cancer cells affect survival?

Answer 25

PDL-1 stops the immune system recognising the cancer cells - reduced survival rates.