CANCER GENETICS

Question 1

what are the influential factors upon cell mass?

Answer 1

proliferation, differentiation, cell contacts, extracellular matrix, blood supply, cell death, immune attack cancer cells

Question 2

what does the control of normal cell growth require?

Answer 2

Requires growth factors to signal the cell to enter the cell cycle

Question 3

how does the cell cycle ensure cell growth?

Answer 3

has internal check points that make sure DNA replication and mitosis are going ahead without errors

Question 4

what happens if errors are detected at check points?

Answer 4

the cell cycle is stopped, & the damage/error is repaired

Question 5

How do cancer cells arise?

Answer 5

Cell growth is usually a highly regulated process

When derailed, new cells are produced in an uncontrolled manner

Question 6

what are the cell masses called?

Answer 6

tumours (cancerous) or neoplasms (new growth)

Question 7

what is transformation?

Answer 7

The process of changes within a cell that lead to a neoplasm

Question 8

what are benign neoplasms?

Answer 8

restricted to one ‘clump’ of cells – not cancerous – does not spread

Question 9

what are metastatic neoplasms?

Answer 9

rare – primary cancer is not found - spreads

Question 10

what are Familial cancers?

Answer 10

Inherited in families – high penetrance genes

Question 11

what are Sporadic cancers?

Answer 11

Acquired in one’s life-time - population – combination of low penetrance genes

Question 12

what are the causes of genetic damage that lead to cancer?

Answer 12

Cancer cells are clonal
Some chromosomal aberrations are associated with cancer
Exposure to chemicals that damage DNA increases the incidence of cancer
Infection with an oncovirus can lead to cancer

Question 13

what is carcinogenesis?

Answer 13

the process of inducing cancer

Question 14

how do cells get properties of cancer?

Answer 14

A population of cells acquire a series of genomic mutations

These mutations give the cells the hallmarks of cancer

Question 15

what 2 sorts of genes do the hallmarks of cancer arise in?

Answer 15

Oncogenes

Tumour-suppressor genes

Question 16

what are the different types of small scale mutation?

Answer 16

point
insertion
deletion

Question 17

what are point mutation?

Answer 17

silent, missense, nonsense

Question 18

what are the different types of large-scale mutations?

Answer 18

amplification, deletion, translocation, inversion, loss of heterozygosity

Question 19

what are oncogenes?

Answer 19

only 1 genetic change in proto-oncogene

Question 20

what are oncogenes dominant to?

Answer 20

Dominant to WT (GAIN of function Constitutive, excessive or inappropriate activity

Question 21

what do oncogenes stimulate?

Answer 21

cell growth in response to growth factors

Question 22

what are tumour suppressors?

Answer 22

2 genetic/epigenetic changes (both alleles)

Question 23

what are tumour suppressors recessive to?

Answer 23

Recessive function to WT (LOSS of function)

Question 24

what do tumour suppressors repress?

Answer 24

Repress aberrant cell growth/entry into cell cycle

Question 25

what are Proto-oncogenes?

Answer 25

genes which encode for components of cell signalling pathways which promote cell growth and division

Question 26

what happens when Proto-oncogenes become mutated?

Answer 26

they become oncogenes

Question 27

what do oncogenes do?

Answer 27

`drive’ the cell to divide (hallmark 1)

Question 28

what do oncogenes trigger?

Answer 28

Oncogenes trigger cell transformation

Question 29

what are viral oncogenes?

Answer 29

essentially copies of a group of genes found in humans (porto-oncogenes)

Question 30

what do Proto-oncogenes control?

Answer 30

control key processes in cell growth

Question 31

what cell growth processes do Proto-oncogenes control?

Answer 31

growth factors, transcription factors, cyclins

Question 32

how do Proto-oncogenes become activated oncogenes?

Answer 32

via gain of function events

Question 33

what are gain of function events?

Answer 33

Activation by amplification, mutation, chromosomal rearrangement

Question 34

give examples of oncogenes

Answer 34

her 2 ras VEGF

Question 35

what is the normal function of tumour-suppressor genes?

Answer 35

to inhibit cell proliferation and in some cases, trigger apoptosis

Question 36

where do tumour-suppressor genes work?

Answer 36

at cell cycle check points

Question 37

when do tumour suppressor genes stop the cell cycle?

Answer 37

If DNA damage has occurred, or mitosis has gone wrong

Question 38

what happens once the cell cycle has been stopped?

Answer 38

cell `rests’ and repair is made to DNA or chromosomes

Question 39

what happens if the cell can't be repaired?

Answer 39

cell undergoes apoptosis

Question 40

what do tumour suppressors prevent?

Answer 40

prevent inappropriate entry into cell cycle

Question 41

what do tumour suppressors promote?

Answer 41

cell death of cancer cells by apoptosis

Question 42

what do tumour suppressors maintain?

Answer 42

genome stability

Question 43

what do tumour suppressors control?

Answer 43

the micro-environment around the cells

Question 44

what are tumour suppressors classified as?

Answer 44

Gatekeeper genes Caretaker genes Landscaper genes

Question 45

what do Gatekeeper genes do?

Answer 45

regulate cell division or growth

Question 46

what do Caretaker genes do?

Answer 46

DNA repair or the DNA damage response

Question 47

what do Landscaper genes do?

Answer 47

modulate the micro-environment in which tumour cells grow

Question 48

are mutations in tumour suppressor genes dominant or recessive?

Answer 48

generally recessive

Question 49

why are tumour suppressor genes recessive?

Answer 49

both alleles must be mutated (inactive) in order for the gene to stop functioning

Question 50

give examples of tumour-suppressor genes

Answer 50

Rb retinoblastoma gene p53 (TP53) BCRA1 and BRCA2

Question 51

why do viruses cause cancer?

Answer 51

they enhance proliferation and predispose cells to cancer, but are NOT sufficient to induce complete transformation

Question 52

what is the relationship between cancer risk and age?

Answer 52

as age increases the number of cancer cases increases

Question 53

what is the multi-stage model (‘Vogelgram’)?

Answer 53

``` external growth signals anti-growth signals apoptosis Immortality angiogenesis metastatic ```