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Lecture 2.27: Viruses and Cancer (Oncogenes & Tumor Suppressor Genes)

Terms in this set (12)

Oncogene
An altered gene whose product acts in a dominant manner to accelerate cell growth or cell division
Mutation
Which mechanism of activating oncogenes does this compound apply to?

A classic example is point mutation of the RAS oncogene. This results in the gene product, a small GTPase, having less activity in tumors and in resultant stimulation of the activity of adenylyl cyclase.
Promoter Insertion
Which mechanism of activating oncogenes does this compound apply to?

Insertion of a viral promoter region near a gene activates it.
Enhancer Insertion
Which mechanism of activating oncogenes does this compound apply to?

Insertion of a viral enhancer region near a gene activates it.
Chromosomal Translocation
Which mechanism of activating oncogenes does this compound apply to?

The basis is that a piece of one chromosome is split off and joined to another. Classic examples are those involved in Burkitt's lymphoma and in the Philadelphia chromosome.
Gene Amplification
Which mechanism of activating oncogenes does this compound apply to?

Abnormal multiplication of a gene occurs resulting in many copies. This can occur with oncogenes and also genes involved in tumor drug resistance.
RAS Oncogene Mutation
Intrinsic GTPase activity is lost
Tumor Suppressor Gene
Produces a protein product that normally suppresses cell
growth or cell division
MYC
Which oncogene/tumor suppressor gene contains the following properties?

• Encodes a DNA-binding transcription factor, P53, that can alter transcription

• Involved in cell growth, cell cycle progression, and DNA replication

• Mutated in a variety of tumors
P53
Which oncogene/tumor suppressor gene contains the following properties?

• Responds to various cellular stresses

• Induces cell cycle arrest, apoptosis, senescence, and DNA repair

• Involved in some aspects of regulation of cellular metabolism

• Guardian of the genome

• Mutated in some 50% of human tumors
RAS
Which oncogene/tumor suppressor gene contains the following properties?

• Encodes small GTPases

• Identified as being the transforming genes of certain murine sarcoma viruses

• Important members are K-RAS, H-RAS, and N-RAS

• Persistent activation due to mutations contributes to development of a variety of
cancers
RB
Which oncogene/tumor suppressor gene contains the following properties?

• Encodes the RB protein

• Regulates the cell cycle by binding the elongation factor E2F

• Represses the transcription of various genes involved in the S phase of the cycle

• Mutation causes retinoblastoma

• Also involved in the genesis of certain other tumors
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