Intro to Neoplasia and Molecular Basis of Cancer Flashcards

1
Q

Neoplasm

A

Clonal proliferation of cells exhibiting uncontrolled growth

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2
Q

Malignant neoplasm

A

Cancer

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3
Q

Carcinogens

A

Cause DNA damage leading to uncontrolled cell growth by acting on specific pathways that control cell growth

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4
Q

Benign tumor

A
  • circumscribed
  • uncontrolled growth but does not invade adjacent tissue
  • well differentiated and resemble tissue of origin
  • slow growth rate
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5
Q

Malignant tumor

A
  • poorly defined
  • infiltrates adjacent tissue
  • poorly or well differentiated
  • fast growth rate
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6
Q

What factors determine tumor growth rate?

A
  • Proportion of dividing cells
  • Rate of division
  • Ratio of division to death
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7
Q

Dysplasia

A
  • Disordered growth usually associated with the epithelium

- May progress to malignant neoplasm

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8
Q

Metastasis

A
  • Defining quality of malignant neoplasms

- Spreading requires a repertoire of abilities acquired through accumulation of mutations

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9
Q

Routes of metastatic spread

A
  • Lymphatic
  • Hematogenous
  • Seeding of body cavities
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10
Q

Oncogene

A
  • Mutated gene that promotes autonomous cell growth in cancer cells
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11
Q

Proto-oncogene

A

Normal counterpart of an oncogene; essential for cell growth and differentiation and still under normal regulatory control

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12
Q

How can a proto-oncogene become an oncogene

A
  • Translocation or transposition to a new promoter => normal growth stimulating protein in excess
  • Gene amplification => normal growth stimulating protein in excess
  • Point mutation within a control element => normal growth stimulating protein in excess
  • Point mutation within the gene => hyperactive or degradation-resistant protein
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13
Q

Oncoprotein

A

Promotes cell growth in the absence of normal growth promoting signals

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14
Q

Tumor suppressor genes

A

Encode proteins that prevent uncontrolled cell growth and division at checkpoints (p53, RB)

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15
Q

What kind of mutations are found in oncogenes?

A
  • Activating mutations are usually missense
  • Overexpression caused by translocation or amplification
  • Activation by translocation and formation of a fusion protein
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16
Q

What kind of mutations are found in tumor suppressor genes?

A
  • Loss of function variants

- Deletions

17
Q

Two hit hypothesis

A

For cancer, both copies of a gene must be damaged

18
Q

Two hit hypothesis: sporadic cancer

A

Each copy of a gene is damaged individually (sequentially)

19
Q

Two hit hypothesis: hereditary cancer

A

One damaged gene is inherited and the second copy is damaged individually

20
Q

Tumor testing

A
  • identifies somatic changes
  • sample = tumor tissue
  • provides diagnostic/prognostic information
21
Q

Germline testing

A
  • identifies germline mutations
  • sample = blood or skin cells
  • gives info about familial cancer risk
22
Q

Cancer predisposition syndromes associated with mutations in oncogenes

A

Autosomal dominant:

  • Multiple endocrine neoplasia type II
  • hereditary neuroblastoma
  • costello syndrome
  • cardio-facio-cutaneous syndrome
  • hereditary papillary renal cell cancer
23
Q

Cancer predisposition syndromes associated with mutations in tumor suppressors

A

Autosomal dominant:

  • retinoblastoma
  • li fraumeni syndrome
  • hereditary breast/ovarian cancer
  • familial adenomatous polyposis
  • cowden syndrome - PTEN hamartoma syndrome
24
Q

pRB

A
  • Tumor suppressor gene

- Inhibits G1 -> S transition via a cyclin D-Cdk4/6 mediated mechanism

25
Q

p53

A
  • tumor suppressor gene
  • activated by stress: DNA damage, oncogene activation, hypoxia
  • induces apoptosis
26
Q

Cancer predisposition syndromes associated with chromosome instability

A

All are autosomal recessive:

  • Ataxia telangiectasia
  • Fanconi anemia
  • Nijmegen breakage syndrome
  • Bloom’s syndrome