Oncopathology 2 Flashcards
growth-inhibitory signals is which type of cancer gene ?
Tumor suppressor Genes
What will happen if the Tumor Suppressor Genes are not active?
the cells become refractory to growth inhibition
How do these tumor suppressor genes work? How do they produce their effect on growth inhibition?
Or what are their mechanisms ?
1- Quiescence
2- (Senescence)
3-Checkpoint inhibition
4-Initiating apoptosis in the cell.
Explain the Quiescence mechanism?
Forcing the cell to enter the G0 phase of cell cycle
Explain the (Senescence) mechanism?
Permanent prevention of replication
Explain the Checkpoint inhibition mechanism?
And give example……
Inhibition of progress of the cell through the cell cycle
One example is : CDKI (cyclin dependent kinase inhibitors)
Inactivation of tumor suppressor genes requires inactivation of both / one
allele of the gene.
Both
Inactivation of both alleles is known as “……………….” (LOH)
Loss of Heterozygosity
Inactivation of both alleles is known as “Loss of Heterozygosity” (LOH)
and is the basis of ………….hypothesis of carcinogenesis
Knudson’s two hit
Inherited susceptibility (inherited cancer susceptibility) of cancer already have Homozygous /heterozygote state, one normal allele and one damaged allele, so he needs one/two hit to develop cancer ?
Heterozygote
One
in the sporadic ( not inherited) cases both alleles are normal So it is homozygote/ Heterozygous so he needs two/ one hits
homozygote
Two
Knudson’s two-hit hypothesis of carcinogenesis what we mean by hit ?
hit means inactivation
Knudson’stwo-hit hypothesis of carcinogenesis this hypothesis explains
why patient with inherited cancer develop cancer quicker/ slower than patient with no previous predisposition (Sporadic).
Quicker
However in the sporadic cases (one/ both) alleles are normal (homozygote) so he needs (one /two) hits, the first one (will/will not)develop cancer because tumour suppressor gene is (recessive/dominant) and this requires the two genes to be damaged. After the (first/second)hit he developed the heterozygous state. Once he have the second hit develop (heterozygote / homozygote) state
1-Both
2-two
3- will not
4-recessive
5-first
6-heterozygote
Give me 4 examples of tumor suppressor genes ?
- RB gene
- TP53 gene
- NF1 (Neurofibromin)
- NF2 (Merlin)
- APC (Adenomatous Polyposis Coli)
tumor suppressor gene,(one hit is /two hits are ) required?
Two
……………gene is the most commonly mutated gene in human cancers
TP53
The product of TP53 gene is known as…….
p53 protein.
…….Governor of the cell cycle
RB رؤى العنبري
Which gene is the Guardian of the Genome?
Tp53
p53 functions to protect the cell from neoplastic transformation by 3
main mechanisms:
- Activation of temporary cell cycle arrest (quiescence).
- Induction of permanent cell cycle arrest (senescence).
- Triggering programmed cell death (apoptosis)
When the p53 get activated?
Give me examples
p53 can be activated by various stressful stimuli that put the cell into danger of neoplastic transformation
includes DNA damage, excessive growth stimulating signals, and hypoxia.
P53 can initiate apoptosis or repair DNA by itself ( ✅ or ❌ )
❌
P53 (can not )initiate apoptosis or repair DNA by itself. However, it activates the transcription factors that are
necessary to do these functions
How do tumor cells invade the extracellular matrix?
What are the 3 steps
1-Loosening of intercellular connections between tumor cells
2-Degradation of the ECM through proteolytic enzymes
3- Locomotion (Movement and migration of the cells).
E-cadherins is………… molecule
adhesion
في ال junctions
What is the function of proteolytic enzymes?
Degradation of the ECM In the (Invasion of Extracellular matrix (ECM))
Give me one example of proteolytic enzymes:
Matrix Metalloproteinases or MMPs