Cancer Genetics Flashcards

1
Q

Oncogenes

A
  • mutations are gain of function
  • provide a persistent proliferative signal
  • usually dominant
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2
Q

Tumor suppressor genes

A
  • mutations are loss of function
  • gatekeeper tumor suppressors: control cell cycle
  • caretaker tumor suppressors: protect the integrity of the genome
  • recessive
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3
Q

Mutations that can turn a proto-oncogene into an oncogene

A
  • hyperactive protein made in normal amounts
  • normal protein greatly overproduced
  • nearby regulatory DNA sequence causes the normal protein to be overproduced
  • fusion to actively transcribed gene produces hyperactive fusion protein
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4
Q

HER2/Neu

aka ERBB2

A
  • member of the epidermal growth factor receptor family
  • mutations are common in sporadic breast cancer
  • point mutations create a constitutively active protein
  • oncogene
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5
Q

Myc

A
  • 3 members: c-myc (rapidly proliferating cells), N-myc (pre-B cells, kidney, brain and intestine), and L-myc (embryogenesis and in kidney and lung)
  • transcription factors with roles in controlling cell cycle progression, apoptosis and trasformation
  • upregulates cyclins, downregulates p21, downregulates Bcl-2
  • hyperactive myc associated with many types of cancer
  • N-myc specifically with neuroblastoma
  • oncogene
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6
Q

Burkitt’s Lymphoma

A
  • chromosomal translocation t(8;14)
  • fuses IgH and Myc
  • B cells have high expression of IgH -> when fused leads to high expression of myc -> lymphoma
  • fastest growing human tumor
  • associated with EBV and malaria
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7
Q

BCR-ABL

Philadelphia chromosome

A
  • t(9;22)
  • fusion of BCR (breakpoint cluster region) with ABL kinase
  • associated with chronic myelogenous leukemia (CML)
  • oncogene
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8
Q

Examples of tumor supressors

A

Rb, p53, BRCA1/BRCA2, MLH1, MSH2

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9
Q

Oncomirs

A
  • microRNAs that regulate the expression of either tumor suppressors or oncogenes
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10
Q

Features that suggest hereditary cancer

A
  • early onset of cancer
  • multiple primary cancers
  • bilateral cancer
  • clustering in relatives
  • occurrences in multiple generations
  • unusual presentation or histology
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11
Q

Multiple endocrine neoplasia (MEN)

A
  • inherited cancer of endocrine glands
  • autosomal dominant
  • type 1: MEN1 gene is mutated -> tumor suppressor that regulates genes involved in cell proliferation
  • type 2: RET gene is mutated -> oncogene that gives persistent proliferative signal
  • 100% risk if inherited
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12
Q

Li-Fraumeni Syndrome

A
  • rare, associated with a variety of cancers including breast, brain, leukemia, sarcoma, adrenal
  • mutation in p53
  • 90% risk if inherited
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13
Q

Retinoblastoma

A
  • cancer of retina
  • mutations in RB1
  • 99% risk if inherited
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14
Q

Von Hippel-Lindau Syndrome

A
  • predisposed to variety of tumors including eye, brain, spinal cord, kidney, pancreas, and adrenal
  • mutation in tumor suppressor VHL which contains a ub E3 ligase activity and is involved in the degradation of HIF1
  • VHL inhibits formation of blood vessels -> gives rise to highly vascularized tumors
  • 40% risk if inherited
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15
Q

Hereditary breast/ovarian cancer syndrome

A
  • mutations in BRCA1/BRCA2
  • tumor suppressor genes that encode proteins onvolved in the repair of damaged DNA
  • 85% risk if inherited
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16
Q

Hereditary Nonpolyposis Colon Cancer

Lynch syndrome

A
  • colon cancer and endometrial cancer
  • mutations in MLH1 or MSH2
  • proteins involved in mismatch repair
  • increase in point mutations and genetic instability in microsatellite regions -> known as Replication ERor positive (RER+) phenotype
  • 80% risk if inherited
17
Q

Familial Adenomatous Polyposis (FAP)

A
  • colorectal cancer
  • mutations in tumor suppressor APC -> normally inactivates beta-catenin -> overexpression of genes encoded by beta-catenin (myc)
  • 100% risk if inherited
18
Q

Neurofibromatosis

A
  • usually benign tumors of the nervous system

- type 1: mutations in NF1, a negative regulator of the Ras pathway