What two genes activated by myc lead to Rb phosphorylation?
Cyclin D gene
SCF gene
What ubiquitin ligase degrades p53?
Mdm2
What does protein kinase ATM do?
Phosphorylates p53 so Mdm2 can no longer bind to it and degrade it
How can p53 halt the cell cycle?
Once p53 is active it binds to p21--p21 levels increase and the inhibitor protein binds (hugs) the G1/S-CdK and the G1-CdK keeping it in an inactive state
Is CAK or Wee1 the activating phosphatase when activating M-CdK?
CAK
How does CDC25 remove the inhibiting phosphate?
CDC25 is phosphorylated via S-CdK and removes it
How many checkpoints are in the cell cycle?
3 total
When does the G2 checkoint occur?
Right before M phase
How does M-CdK activate the APC?
It phosphorylates the APC allowing CdC20 to bind to it
What does APC do when it is active?
It ubiquinates the securin--the securin degredation activates seperase
What does seperase do?
It cleaves the cohesions and allows the sister chromatids to be pulled apart
What 7 genes could you knock out that would lead to cell proliferation?
p1, p21, p27, p53, securin, ATM, Rb
What is necrosis?
Accidental cell death
What are the characteristics of apoptosis?
Cell shrinks & membrane blebbing occurs
The nucleus condenses
DNA fragments into mono & oglionucleosomes
Apoptotic bodies are ingested by macrophages
What signals phagocytosis of the apoptoic bodies?
phosphatidylserine on the outer layer of the plasma membrane
Name 2 examples of apoptosis in health?
Shedding of the endometrium during mensturation
Neutrophils during an acute inflammatory response
Name two post- mitotic cells that undergo apoptosis due to aging?
cardiac myocytes
skeletal myocytes
Is procaspase active or inactive?
Inactive
Mitochondrial medicated signaling is induced if there is mitochondrial dysfunction, what are two signals that tell the cell the mitochondria is dysfunctioning?
Increased ROS/RNS
Decreased ATP
What makes up the apoptosome?
Cytochrome c
dATP
Apaf-1
Procaspase 9
What triggers the release of cytochrome-c?
Bax
t-Bid
What activates Procaspase 9?
It cleaves itself causing activation
What inhibits the release of cytochrome-c?
Bcl-2
What does XIAP inhibit?
The activity of caspase 9 & caspase 3, inhibiting apotosis
What does Smac/Diabloe & OmiHtrA2 do?
Inhibits XIAP allowing Caspase 9 and 3 to continue apoptosis
What does Caspase 3 do after it is active?
Cleaves and degrades ICAD, also Caspases 6 & 7, and the cytoskeleton (causing blebbing)
Name 4 things p53 can do.
halt the cell cycle
stimulate DNA repair
induce apoptosis
alters transcription of pro/anti apoptotic genes
True or false, the cell expressing the Fas Ligand will undergo apoptosis.
False-the cell expressing the Fas RECEPTOR will undergo apoptosis
Fas is also known as?
CD95
Fas-L is also known as?
CD95L
What is on the cytosolic side of the Fas receptor?
FADD (Fas associated death domain) protein
What does FADD do?
It recruits Procaspase 8 inducing self cleavage and activation
What dose cFLIP do?
Inhibits the activation of Procapase 8
What is a DISC?
death inducing signaling complex
it is made up of: Fas receptor, FADD, procaspase 8
What does malignant mean?
tending to infiltrate, metastasize and terminate fatally
What is it called when a tumor changes from benign to malignant?
Transformation
What does activation mean?
conversion of a proto-oncogene to an oncogene
What advantage does abnormality or a genetic defect have?
a replicative advantage over other cells
What are the 7 hallmarks of cancer?
1-genetic instability,
2-self-sufficiency in growth signals,
3-insensitivity to growth inhibitory signals,
4-evasion of apoptosis,
5-limitless replicative potential,
6-sustained angiogenesis,
7-tissue invasion & metastasis
Explain self-sufficiency in growth signals .
There is an increase in the number of GF receptors and the mutant ones begin to transmit signals without GF
What types of mutations must occur to acquire an insensitivity to growth inhibitory signals?
mutations blocking receptors for growth inhibitory signals, also mutated p53 and Rb
What allows for limitless replicative potential?
cancer cells reactivate telomerase which allows the cells to divide indefinitely
Tumor suppressor genes cause a loss of function mutation, is it dominant or recessive?
Recessive and requires the loss of both alleles
Oncogenes cause a gain of function mutation is it dominant or recessive?
Dominant and requires the loss of only one allele
What is nondisjunction?
chromosome loss that occurs during replication when one daughter cell gets both sets of chromosomes and the other cell gets none
Which receptor is responsible for ~25% of breast cancer?
HER-2
What is a deletion mutation?
removal of one or more base pairs
How does HER-2 cause breast cancer?
overexpression of the HER-2 receptor will begin to homodimerize without any ligand binding, thus, activating itself and cause excessive cell proliferation
How does Herceptin treat breast cancer?
it is an antibody that inactivates the receptor and inhibits the signal that causes the excessive cell proliferation
What causes chronic myelogenous leukemia?
There is a translocation of Bcr/Abl gene that leads to excessive cell proliferation
What is overexpressed in B-cell lymphoma?
Bcl-2 (gain of function mutation)
How does anti-sense therapy work?
it makes a complimentary mRNA strand that will bind to the RNA molecule and both will be degraded, this process could inhibit the overexpression of all the genes that are anti-apoptotic
What is angiogenesis?
Making of new blood vessels from existing blood vessels
What causes the onset of angiogenesis?
imbalance between upregulation of pro-angiogenic factors and downregulation of anti-angiogenic factors
What does VEGF do?
potent stimulus for angiogenesis
What does VEGF stand for?
vascular endothelial growth factor
What three things stimulate VEGF?
hypoxia (HIF binds to VEGF and induces transcription),
mutations (in p53 results in an overexpression of VEGF), activation (of Ras leads to overexpression)
What can degrade VEGF?
MMP’s (matrix metalloproteinase) degrade the basement membrane
What do pericytes do?
they detach from the blood vessel while angiogenesis is occurring then they reattach after the basement membrane is formed
What are pericytes?
they are cells related to vascular smooth muscle located adjacent to & surround the endothelium
True or false, soluble VEGF receptors are NOT a natural part of the body?
False, they are a natural part of the body
What is invasion?
migration of cancer cells break through the barrier that keeps them localized
What must cancer cells acquire to become malignant and survive in circulation?
the invasive phenotype
Name the 7 steps of metastasis.
1-tumorigenesis,
2-angiogenic switch,
3-acquire invasive phenotype,
4-survival in circulation,
5-extravasation & growth at secondary site,
6-angiogenesis in secondary tumor,
7-evasion of immune response
What is the angiogenic switch?
the tumor is now secreting VEGF and is stimulating angiogenesis
What is tumorigenesis?
tumor formation that has acquired many mutations and has a proliferative advantage
What is this called when the tumor cells kill the immune cells?
immune privilege
What does HPV (Human papilloma virus) do?
inactivates p53 and Rb
Are the cells infected with Epstein-Barr virus (EBV) more or less resistant to apoptosis?
Less resistant, there is an increased expression of survival proteins
Tumor cells with low Fas ____ apoptosis by cytotoxic T cells.
resist
Tumor cells with FasL expression _____ apoptosis in cytotoxic T cells.
