Tumour Pathology 5 Flashcards

1
Q

How do tumour suppressor genes function?

A

Discourage cell growth or temporarily halt cell division to carry out DNA repair

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2
Q

What is an anti-oncogene?

A

A tumour suppressor gene

Responsible for Apoptosis
DNA repair and the negative regulation of mitosis

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3
Q

What do mutations in retinoblastoma gene cause?

A

Favour cell proliferation since it is an anti-oncogene (a tumour suppressor gene)

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4
Q

What other mutations can cause the same effect of a mutated RB gene?

A

Mutational activation of Cyclin or CDK (naturally responsible for the phosphorylation of the pRB)

Mutational inactivation of CDKI’s

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5
Q

What is the inherited form of oncogenesis?

A

One defective copy of the RB gene
Somatic point mutation of the other copy

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6
Q

What is the sporadic form of oncogenesis?

A

Both hits occur in a single cell

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7
Q

What portion of cancers are hereditary?

A

5-10% of all cancers

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8
Q

Give two examples of inherited cancer syndromes?

A

Familial retinoblastomas
Familial adenomatous polyposis of colon

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9
Q

What gene is responsible for signal transduction and also FAP colon cancer?

A

APC

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10
Q

What gene is responsible for cell cycle regulation and causes retinoblastoma and osteosarcomas?

A

Rb

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11
Q

What gene inhibits CDK’s and causes malignant melanoma?

A

p16 (INK4a)

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12
Q

Which gene is responsible for DNA repair and causes breast and ovarian cancer?

A

BRCA 1/2

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13
Q

What can cause alteration of proto-oncogene structure?

A

Point mutation
Chromosome rearrangements and translocations

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14
Q

What can cause dysregulation of proto-oncogene expression?

A

Gene amplification
Overexpression

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15
Q

Give examples of oncoprotein products

A

Growth factors
Growth factor receptors
Proteins involved in signal transduction
Nuclear regulatory proteins
Cell cycle regulators

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16
Q

What mutation of the PDGF growth factor causes Astrocytoma and osteosarcoma’s?

A

Over expression

17
Q

What mutation of the growth factor receptor EGF causes Breast ovarian lung and stomach cancer?

A

Amplification

18
Q

What mutation in GTP binding signal transducaers causes lung, colon, pancreas, leukaemia

A

Point mutation

19
Q

What mutation in transcriptional activators (a nuclear regulatory protein) causes

A

Burkitt lymphoma

20
Q

What type of mutation are cell cycle regulators Cyclin D and CDK4 susceptible to?

A

Amplification
Cyclin D also susceptible to translocation

21
Q

What type of cancer can a mutation in Cyclin D cause?

A

Translocation - mantle cell lymphoma
Amplification - breast, liver, oesophageal

22
Q

What type of cancer does a mutation in cyclin dependant kinase cause?

A

melanoma, sarcoma

23
Q

What are the mechanisms of viral carcinogenesis?

A

Virus genome inserts near a host proto - oncogene

Viral promoter or other transcription regulator causes proto-oncogene over expression

Retroviruses insert oncogene into host DNA causing cell division.

24
Q

Chemical carcinogenesis involves adduct formation, what does this lead to?

A

Activation of oncogenes and suppression of anti-oncogenes

25
Q

What is a neoplasm?

A

A new and abnormal growth of tissue in the body.

26
Q

What is the function of the p16 protein?

A

It is an inhibitor of the CDK’s which are involved in the phosphorylation of the of the pRB - progression from G1 to S phase

27
Q

What happens when pRB is bound to E2F?

A

The complex acts as a growth suppressor - prevents progression through the cell cycle

When unbound - no inhibition exists - progression is possible.