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PP Lecture Summaries > Neoplasia 3 > Flashcards

Neoplasia 3 Flashcards

1
Q

What are intrinsic factors that contribute to neoplasia?

A

Host factors;

  • Age
  • Gender (hormonal)
  • Genetics
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2
Q

What are extrinsic factors that cause neoplasia?

A

Environment and behaviour

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3
Q

What are behaviour factors that incrase risks of cancer?

A
  • high bmi
  • low intake of fruit and veg
  • lack of exercise
  • tabacco use
  • alcohol consumption
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4
Q

What are the main extrinsic carcinogenic categories that lead to neoplasia (environmental)?

A

Chemicals
Radiation
Infections

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5
Q

What are some examples of chemical carciogenic agents?

A

2-napthylamine- used in dying of fabrics
Asbestos
Coal tars
Vinyl chloride

(Normally limited to effecting working in that field)

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6
Q

How do chemical carcogens assert their effect?

A

Long delay between exposeure and development
Risk dependant on dosage
Some are organ specific

Act as initiators
Some are pro-carcogens (need converting by cytochrome P450 enzyme to assert effect

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7
Q

What are carcogens called that can act as both initiators and promotors?

A

Complete carcogens

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8
Q

What types of radiation are carcogenic?

A

UV (daily exposure)

Ionising radiation from backgroud Radon

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9
Q

How does radiation assert its effect?

A

Directly- damages DNA bases and causes strand breaks

Indirectly- generating free radicals

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10
Q

How can infections act as carcogenic agents?

A

Directly- affecting genes that cause cell growth

Indirectly- damage tissue chronially (causing regeneration that acts as a promoter or causes new DNA replication errors)

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11
Q

What type of infections act as direct carcinogenic agents?

A

HPV- inhibits p53 and pRB protein function

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12
Q

What type of infetions act as indirect carcogenic agents?

A

Hep B&C- (liver damge and regeneration)
Bacteria & parasites
Helicobacter pylori- (Gi inflammation in bile ducts and bladder mucosa)
HIV- (lowers immunity)

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13
Q

What percent of cancer risk is due to environmental factors?

A

85%

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14
Q

How can we tell that the environemnt/ country influences the risk for cancers?

A

Migrants moving from Japan

  • through generations reduced cases of gastric cancer
  • increased cases of breast cancer

Shows risk factors changed/ not the same in both coutries

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15
Q

How does HPV increase cancer risk?

A

Produces E6 and E7

E6 inhibits p53 (prevents apostosis of cell)
Interferes with Retinoblastoma protein (which is a cell cycle checkpoint)

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16
Q

What cancer is HPV related to?

A

Cervical carcinoma

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17
Q

How do mutations in the retinoblastoma gene increase risk?

A

Is a tumour surpressor gene (mutations lead to excessive proliferation)
Need mutations in both alleles

If germline mutation in RB1 gene speeds up initiation process

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18
Q

What is the RAS gene?

A

Oncogene

Mutated in 15-20% of maligant neoplasms

Activated from causes Cyclin D to be produced

19
Q

How can RAS mutations cause increase cancer risk?

A

No longer needs GF stimulation
Cyclin D constantly produced

More Retinoblastoma 1(Rb) phosphorylated
Cell cycle passes checkpoint

If Rb1 also mutated this process extrapolated

20
Q

What types of DNA repair genes are common sites of mutations?

A

Nucleotide exision repair
Mismatch repair
DNA double stranded repair breaks

21
Q

What do caretaker genes do?

A

Prevent accumilation of DNA damage

Mutations in these genes can be inherited

22
Q

What caretaker gene is mutated in Xeroderma Pigmentosa?

A

Genes that affect DNA nucleotide excision repair

23
Q

What is Xeroderma Pigmentosa?

A

Autosimal recessive

Sensitivity to UV and young development of skin cancer

Inability to repair dna damage from UV

24
Q

What caretaker genes are mutated in Familia breast carcinoma?

A

BRAC1/BRAC2

Gene that repairs double stranded DNA breaks

25
Q

What caretaker gene mutations cause Hereditary non-poliposis colon cancer symdrome (HNPCC)?

A

DNA mishmatch repair genes

26
Q

What is HNPCC?

A

Autosomal dominant
Associated with colon cancer at a younger age
DNA not repaired

27
Q

What is the 2 hit hypothesis?

A

That in recessive genes need mutations to both alleses to become mutated.

This requires two mutations to occour

This process in speeded up in inherited diseaes as already get first hit from germ line
(Only need to get 1 sporadic mutation so cancer younger)

28
Q

What is retinoblastoma?

A

Inherited mutation in the Retinoblastoma protein (which is an important tumour surpressor gene in cell cycle checkpoint)

RB1 gene

Both alleles need to be mutated for effect but as already have one develop retinoblastoma tumours younger

29
Q

What does retinoblastoma cause?

A

Tumours in the retinas of the eyes

If get inhertited gene likely affect both eyes
If due to sporadic mutations, likely to only affect one one eye

30
Q

What is Familial adenomatous polyposis (FAP)?

A

Mutation in APC tumour supressor gene

Leading to development of many adenomatous colon polyps

31
Q

How does FAP cause colon cancer?

A

Untreated polyps can develop into cancerous masses by mid 40s

Already have monclonal mutated cell population

32
Q

What is the role of c-mcy?

A

Is a proto-oncogene that drives transcription and inbibits genes with antiproliferative functions

33
Q

What cancers have muatated c-mcy genes?

A

Breat
Lung
Ovarian
Prostate

34
Q

How does c-mcy oncogene contribute to tumour cell formation?

A

Blocking cellular senescence and differentiation

Changes tumor environment (activates angiogenesis, surpresses hosts immune response)

35
Q

What is the Her-2 proto-oncogene?

A

Produces HER2 protein and aids in normal cellualr growth, division and repair of breast tissue

36
Q

How does HER2 oncogene contribute to neoplasia?

A

In some breast cancer too many copies are produced (HER2 amplification)

Too many HER2 genes- too many HER2 receptors
Breast cells grow in uncontrolled mannor

37
Q

How does ulcerative colitis increases malignancy risk?

A

Due to severe ongoing inflammation
Constant regeneration of tissue
More chnaces for initioation of mutations
Promotion can occour at a faster rate

38
Q

How does Cirrohsis increase risk of malignancy?

A

Due to chronic imflammation and repair/ regeneration of hepatocytes
Increased opportunities for DNA changes to occour and be promoted

39
Q

What medical conditions are associated with increased risk of malignancies developing?

A

Any that involve chronic imflamation

40
Q

What are the stages of carcinogenesis?

A

1- tumour initiation
2- tumour promotion
3-malignant conversion
4-tumour progression

41
Q

What is tumour initiation?

A

Initial carciogenic agent that causes a mutation (noramlly to a gene that alters cell proliferation)

42
Q

What is tumour promotion?

A

The acquired mutation being spread throughout the cell population to create a monoclonal cell population

Some initiators are also promotors

If got mutation via germ line this step is skipped

43
Q

What is tumour progression?

A

The expression of the maligant phenotype and the tendency of cells to acquire more aggressive characteristsics over time.

Get more mutations that alter cell prolifertaion genes

PP Lecture Summaries (9 decks)

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