Wiki Flashcards Oncogene

Question 1

What was the first discovered oncogene in 1970?

Answer 1

Src, chicken retrovirus. Steve Martin.

Question 2

What is an oncogene?

Answer 2

A gene that has the potential to cause cancer. In tumour cells, they are often mutated or expressed at high levels.

Question 3

What is a proto-oncogene?

Answer 3

A normal gene that could become an oncogene due to mutations or increased expression. Proto-oncogenes code for proteins that help to regulate cell growth and differentiation. Proto-oncogenes are often involved in signal transduction and execution of mitogenic signals, usually through their protein products.

Question 4

RAS, WNT, MYC, ERK and TRK are all examples of what?

Answer 4

Proto-oncogenes.
The MYC gene is implicated in Burkitt’s Lymphoma, which starts when a chromosomal translocation moves an enhancer sequence within the vicinity of the MYC gene. The enhance sequence causes the transcription factors that the MYC gene codes for to be highly expressed causing uncontrolled cell growth.

Question 5

What is the MYC gene implicated in?

Answer 5

It is a proto-oncogene implicated in Burkitts lymphoma. Which starts when a chromosomal translocation moves an enhancer sequence within the vicinity of the MYC gene. The enhance sequence causes the transcription factors that the MYC gene codes for to be highly expressed causing uncontrolled cell growth.

Question 6

How is the MYC proto-oncogene believed to play a role in Burkitts lymphoma?

Answer 6

BL starts when a chromosomal translocation moves an enhancer sequence within the vicinity of the MYC gene. The enhance sequence causes the transcription factors that the MYC gene codes for to be highly expressed causing uncontrolled cell growth.

Question 7

What type of mutation is involved in the transformation of MYC gene? Burketts Lymphoma?

Answer 7

Chromosomal translocation of an enhancer region.

“Which starts when a chromosomal translocation moves an enhancer sequence within the vicinity of the MYC gene. The enhance sequence causes the transcription factors that the MYC gene codes for to be highly expressed causing uncontrolled cell growth”.

Question 8

Another example of an oncogene is the Bcr-Abl gene found on the __________ Chromosome. A piece of genetic material seen in CML. What does CML stand for?

Answer 8

Bcr-Abl
Philadelphia Chromosome.
A piece of genetic material seen in Chronic Myelogenous leukemia.

Caused by the translocation of pieces from chromosomes 9 and 22.

Question 9

Bcr-Abl is implicated in CML. What is it caused by?

Answer 9

Translocation from ch 9 and 22.

Question 10

Translocation from ch 9 and 22 causes what?

Answer 10

Bcr-Abl, implicated in CML, see also Philadelphia Chromosome.

Question 11

What are 5 examples of proto-oncogenes?

Answer 11

RAS
WNT
MYC - Burkitts Lymphoma, chromocomal translocation of enhancer region. 
ERK
TRK

Question 12

What does Bcr-Abl code for? what are the implications of mutations to this?

Answer 12

It codes for a tyrosine kinase, which is constitutively active, leading to uncontrolled cell proliferation.

Question 13

What are the basic methods of proto-oncogene activation?

Answer 13

1.A mutation within a proto-oncogene, or within a regulatory region (for example the promoter region), can cause a change in the protein structure, causing: an increase in protein/enzyme activity and/or a loss of regulation.

2. An increase in the amount of a certain protein (protein concentration), caused by:
   An increase of protein expression (through misregulation).
   An increase of protein (mRNA) stability, prolonging its existence and thus its activity in the cell.
   Gene duplication (chromosome abnormality), resulting in an increased amount of protein in the cell.
3. A chromosomal translocation (another type of chromosome abnormality)
   There are 2 different types of chromosomal translocations that can occur:
   translocation events which relocate a proto-oncogene to a new chromosomal site that leads to higher expression
   translocation events that lead to a fusion between a proto-oncogene and a 2nd gene (this creates a fusion protein with increased cancerous/oncogenic activity)

Question 14

A mutation within a proto-oncogene, or within a regulatory protein can cause what?

Answer 14

a change in the protein structure, causing: an increase in protein/enzyme activity and/or a loss of regulation.

Question 15

What can cause an increase in the amount of a certain protein?

Answer 15

an increase of protein expression (through misregulation)

an increase of protein (mRNA) stability, prolonging its existence and thus its activity in the cell

gene duplication (one type of chromosome abnormality), resulting in an increased amount of protein in the cell

Question 16

What are the two different types of chromosomal translocations that can occur?

Answer 16

1. Translocation events which relocate a proto-oncogene to a new chromosomal site that leads to higher expression (or moves enhancer region close to proto-oncogene) like MYC gene.
2. Fusion events between a proto-oncogene and a 2nd gene.

BCR-ABL is an example of this, codes for a tyrosine kinase enzyme, 22 and 9, activates other proteins that are involved in cell cycle and cell division which can cause a cell to grow and divide uncontrollably.

Question 17

What are oncomirs?

Answer 17

MicroRNAs that control gene expression by downregulating them.

Could be treated with antisense messenger RNA.

Question 18

How could oncomirs be treated?

Answer 18

antisense mRNA technically.

Question 19

Increased activity of oncomirs in tumour cells indicates

Answer 19

They are the type that normally suppress TSGenes and have been overexpressed

Question 20

Decreased activity of an oncomir in a tumour cell indicates

Answer 20

They are the type that normally prevents uncontrolled cell growth but they are being attenuated,

Question 21

The miRNAs miR-15a and miR-16-1 are down regulated in B-cell chronic lymphocytic leukemia. When was this discovered?

Answer 21

2002.

Question 22

miRNAs downregulated in B-cell lymphocytic leukemia are what two?

Answer 22

miR-16-1

miR-15A

Question 23

How is the Epstein-Barr virus (EBV) and miRNAs linked?

Answer 23

Viruses have also been found to have miRNA that mimic parts of natural regulatory human miRNA’s. One example is the Epstein–Barr virus (EBV) which is associated with various types of cancer

Question 24

Philadelphia Chromosome is an example of this type of translocation event. This chromosome was discovered in 1960 by Peter Nowell and David Hungerford, and it is a fusion of parts of DNA from chromosome __ and chromosome __`.

Answer 24

Philadelphia Chromosome is an example of this type of translocation event. This chromosome was discovered in 1960 by Peter Nowell and David Hungerford, and it is a fusion of parts of DNA from chromosome 22 and chromosome 9.

Question 25

Philadelphia Chromosome is an example of this type of translocation event. This chromosome was discovered in 1960 by Peter Nowell and David Hungerford, and it is a fusion of parts of DNA from chromosome 22 and chromosome 9.

The broken end of chromosome __ contains the “BCR” gene, which fuses with a fragment of chromosome __ that contains the “ABL1” gene.

Answer 25

The broken end of chromosome 22 contains the “BCR” gene, which fuses with a fragment of chromosome 9 that contains the “ABL1” gene.

Question 26

BCR-ABL: This fused gene encodes for a protein that displays ______ protein _____ ______ activity (this activity is due to the “____” half of the protein).

Answer 26

BCR-ABL”. This fused gene encodes for a protein that displays high protein tyrosine kinase activity (this activity is due to the “ABL1” half of the protein).