Cancer Bio II Flashcards

1
Q

What are oncogenes?

A

genes that are “turned on” in cancer that have a stimulatory effect on cells

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2
Q

What are tumor suppressor genes?

A

genes that are “turned off” in cancer whose products normall negatively regulate cell proliferation, promote apoptosis or maintain in vivo homeostatic growth

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3
Q

What are genomic guardian genes?

A

Genes whose dysfunction may create genomic instability, e.g. DNA repair genes or recombination genes

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4
Q

What are proto-oncogenes?

A

Normal cellular genes that can be altered to a gene that converts a normal cell to a tumor cell

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5
Q

What are four mechanisms of conversion of proto-oncogenes?

A

Mutation within the gene

Translocation e.g. Philadelphia chromosme

Over-expression

Amplification

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6
Q

What is Ras?

A

Oncogene affecting signal transduction

Most cancer-causing mutations affect its ability to hydrolyze GTP

Three types: H-ras, K-ras, N-ras

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7
Q

What is responsible for transforming the activity of H-ras in bladder carcinoma?

A

Single nucleotide chain resulting in Gly->Val

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8
Q

What is Myc?

A

Onco gene involved in cell-cycle regulation, the control of proliferation and development

Activated by chromosomal translocation

Four types: MycC, MycL, MycN, and MycL2

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9
Q

What is ErbB-2?

A

Encodes for a receptor Protein-tyrosine kinase

Oncogene that is activated via gene amplification

Prognostic of highly malignant tumor

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10
Q

What is loss of heterozygosity?

A

Refers to the loss of an allele in tumor DNA compared to matched normal DNA from the same individual

Causes loss of function for a tumor suppressor gene during tumor initiation or progression

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11
Q

What is retinoblastoma?

A

Tumor with distinct genetic inheritance

Caused by both alleles of the Rb protein being lost (Two hit hypothesis)

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12
Q

Why is noninherited retinoblastoma rare?

A

its development requires two independent somatic mutations to inactivate both normal copies of the Rb gene in the same cell

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13
Q

What is p53?

A

Nuclear protein that increases when there is DNA damage

Increases expression of DNA repair enzymes and can cause apoptosis

Mutated in a wide variety of human tumors

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14
Q

How do tumors progress?

A

Angiogenesis - need a blood supply

Invade surrounding tumors - malignancy

Resist immune attack

Extravasate and develop tumors in distant organs

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15
Q

What are positive effectors of Angiogenesis?

A

VEGF

Angiogenin

FGFs

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16
Q

What are negative effectors of Angiogenesis?

A

Angiostatin

Endostatin

TIMPs

Interferon a

17
Q

What are three characteristics of invasive tumor cells?

A

Increased expression of proteases

Increased motility

Increased expression of certain integrins to anchor tumor cells to the basement membrane