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Disease processes > Cell and molecular biology of cancer > Flashcards

Cell and molecular biology of cancer Flashcards

1
Q

Neoplasm =

A

Abnormal growth of tissue that usually forms a mass.

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2
Q

A neoplasm arises when…

A

Balance between cell division, differentiation or death is disrupted.

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3
Q

Benign tumors can still do harm by mechanisms such as

A

Compression

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4
Q

Factors that favour tumor development:

A
  • genetic instability

- microenvironment inflammation

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5
Q

8 hallmarks of cancer:

A
  1. Self-sufficiency in growth signals (oncogenes)
  2. Insensitivity to antigrowth signals (tumor suppressor genes)
  3. Evasion of apoptosis
  4. Replicative immortality
  5. Sustained angiogenesis
  6. Invasion of tissue and metastasis
  7. Reprogramming of energy metabolism
  8. Evasion of immune destruction
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6
Q

Phases of the cell cycle

A 
G1
G0
S
G2
M
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7
Q

Checkpoints in the cell cycle are between

A

G1 - S
G2 - M
Metaphase - anaphase

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8
Q

Quickest phase of the cell cycle

A

Mitosis

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9
Q

Name 2 cells that don’t reenter the cell cycle

A

Neurons

Cardiac myocytes

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10
Q

Main drivers of the cell cycle =

A

Cyclins and cyclin-dependent kinases

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11
Q

What do CDK-Cyclin complexes do?

A

Signal stages of the cell cycle

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12
Q

G1 –> S restriction point

A

In environment favourable?
Is cell bid enough?
DNA damage

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13
Q

G2 –> M transition

A

Is all DNA replicated?
Is environment favourable?
DNA damage

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14
Q

Ex of external signal

A

Growth factors

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15
Q

Decribe 2 pathways activated by ATM when DNA damage is detected which act to arrest the cell cycle.

A

DNA damage - ATM - phosphorylates p53 - increase p21 - p21 inhibits cyclin-CDK - arrest

DNA damage - ATM - phosphylates Chk1/2 - inhibits cdc25 - usually activated cyclin-CDK but is inhibited - arrest

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16
Q

ATM =

A

Ataxia telangiectasia mutated

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17
Q

p21 acts to

A

Block Cyclin-CDK complex so cell cycle will arrest

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18
Q

What phosphorylates Rb?

A

G1-CDK

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19
Q

Rb is usually bound to…

A

E2F transcription factor

20
Q

What is mutated in >50% of all tumours?

A

p53

21
Q

2 main genes mutated in cancer =

A
  • protooncogenes

- tumor suppressor genes

22
Q

E2F function =

A

Transcription factor, DNA synthesis

23
Q

Proto-oncogenes are mutated to

A

Oncogenes

24
Q

Mutations in tumor suppressor need to be…

A

Both alleles need to be mutated or inactivated to completely inactivate tumor suppressor gene

25
Q

Ex of oncogenes

A

Ras

Myc

26
Q

Ex of tumour suppressor genes

A

p53
Rb
BRAC 1/2

27
Q

Oncogenes =

A

Cause pathways to be switched on inappropriately - excessive proliferation and/or promotion of cell survival

28
Q

What do oncogenes code for?

A
  • Growth factors
  • Growth factor receptors
  • Transription factors
  • Cell cycle and apoptosis regulators (e.g. CDK 4)
29
Q

Tumor suppressor genes =

A

Genes whose loss or inactivation can trigger development of cancer. Usually provice negatice control.

30
Q

What would increase someones susceptibility to a mutation in a tumor suppressor gene? (hint - retinoblastoma)

A

Inheriting one mutant allele, only a single mutation can cause a tumor.

31
Q

Gatekeeper genes =

A

Directly regulates cell proliferation, loss directly opens the gates to excessive cell proliferation

32
Q

Ex of gatekeeper genes =

A

p53

Rb

33
Q

Caretaker genes =

A

Maintain genetic stability. Not directly involved with controlling cell proliferation

34
Q

Ex of caretaker genes

A

BRCA1, BRCA 2

35
Q

What normally degraded p53?

A

Mdm2

36
Q

What stabalised p53 to increase numbers?

A

Phosphorylation my ATM

37
Q

p53 upregulated modulator of apoptosis =

A

puma protein

38
Q

Function of Bcl-2

A

Inhibit apoptosis

39
Q

Function of puma

A

p53 - increase puma - inhibits Bcl-2 - Bcl2- usually inhibits apoptosis, apoptosis occurs

40
Q

HPV infection is found in what % of cervical cancers?

A

> 90%

41
Q

HPV produces

A

Oncoproteins E6 and E7

42
Q

Function of HPV oncoproteins

A

E6 = binds to p53, cannot be stabalised if DNA damage

E7 = binds to Rb. Rb not able to sequester transcription factor.

43
Q

‘2 hit-hypothesis’

A

Most genes require multiple mutations for a phenotypic change

44
Q

The 2 hit hypothesis refers to what kind of gene?

A

Tumor suppressor genes

45
Q

Ex of cancer with multiple mutations

A

Colorectal cancer

Disease processes (21 decks)

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