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Summary of Oncology chapters 7 to 14
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The book for the oncology exam is summarized from chapters 7 to 14. This helped me pass the exam.
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Chapter 7 – ApoptosisDNA damage induces apoptosis via
A Caspase 9 activation
B Induction of p53 expression
C Caspase 3 activation
D All three
Briefly explain how triggering of apoptosis in tumor cells can contribute to new therapies
against cancer and give an example of a therapy
- Extrinsic
- intrinsic
• Apoptosis is the regulated and ordenly destruction of a cell trough a genetically
encoded process also known as programmed cell death (PCD)
• Apoptosis is a type of ‘’cell suicide’’ that is intrinsic to the cell
• apoptosis is organized, neat, and tidy, leaving behind little evidence of the
preexisting cell
• The cell undergoing apoptosis is swept clean during phagocytosis by macrophages,
neighbouring cells that recognize molecular flags (phosphatidyl serine). this protein
was first in the inside, but by apoptotic cells it goes to the outside.
Function of apoptosis
Active ATP dependent process
Physological in many organs:
• developmental morphogenesis
• controls cell numbers
• removal of damaged cells (bv. wanneer je verbrand bent)
• negative and positive selection of lymphocytes
• cytotoxic effect of radio- and chemotherapy
Apoptosis in humans
→ Estimation of apoptosis in a human
- 25 x 106 mitoses per second
- 25 x 106 apoptosis per second
- 2.2 kg cells per day will die every day because of apoptosis
Apoptosis Necrosis
Cell shrinkage Cell swells
Membrane blebbing Leaky membranes
Organelles intact Organelles damaged
Apoptotic bodies Cell lyses
Chromatin condensation and fragmentation Chromatin damaged
No inflammation Inflammation. Aangezien de cel ‘ontploft’
komt alles vrij en heb je inflammation.
,Apoptosis morphology in a lymphocyte
Shrinkage of the cell → apoptotic
bodies
MGG = cytoplasma is blauw en de
kern is paars. Meer kern i.v.m.
cytoplasma. Je ziet met drugs nog veel
apoptotic bodies.
Dapi = Je ziet veel apoptotic bodies.
Bij necrosis zie je allemaal gaten in het membraan en dat is
heel typisch voor necrosis.
Apoptosis signalling
• induction of apoptosis
- programmed
- loss of growth factors, of adhesion
- death receptors of the TNFR family
- T- and B-cell antigen receptors
- CTLs
- DNA damage (irradiation, chemotherapy)
- stress conditions
• mitochondrial changes
• activation of the caspase family
• proteolytic cleavage of structural and functional proteins
• induction of apoptosis morphology
,Caspases
• caspases are cysteine-proteases synthesized as zymogens
• requirement for an aspartatic acid at the p1 position
• 14 family members cloned
• capsases 2,3,6,7,8,9 and 10 are involved in apoptosis
• divided into:
- initiators → 2,8,9 and 10
- effectors → 3,6 and 7
- inflammatory → 1,4 and 5 (neurodegeneratieve ziektes involved)
caspase activation
fully processed =
activation
prodomain on the left
larger and small are
connected with the
spacer
in the larger a specific
amino acid, different in
every caspase. this is
important, because
these sequences are
used for activation.
ASP is the amino acid → activation
Four apoptosis pathways
1. intrinsic/stress-induced or
mitochondrial apoptosis pathway
2. extrinsic/death receptor mediated
apoptosis pathway
3. granzyme B mediated apoptosis
pathway
4. ER mediated apoptosis pathway
Two major apoptosis pathways (aandacht voor in dit college)
• apoptosis induced by internal signals: The intrinsic or mitochondrial pathway
• apoptosis triggered by external signals: The extrinsic or death receptor pathway
, intrinsic and extrinsic apoptosis
pathway
extrinsic pathway (right)
activated by cytostic T-lymphocyte
(TRAIL, FAS, TNF-alfa). Adapter
protein (FADD) activated. Pro-caspase
lead to caspase 8 → activate caspase
3,6 and 7 → apoptosis.
Intrinsic (left)
induced by chemotherapy, oncogene.
UV etc. → p53 stabilized → BH3 only
activated (subgroup of BH2 family) →
translocation van cytoplasm to the
mitochondria → formation of
channels in the automembrane →
release of cytochrome C → in the presence of ATP and Apaf-1 → Activation of caspase 9 →
activate caspase 3,6 and 7 → apoptosis
Caspase 3,6,7 bind to different kind of proteins → cleavage of all the proteins → lack of
function → apoptosis
Breakdown of the cell
results from the proteolysis of target proteins
• nuclear lamins
• cytoskeletal proteins (actin)
• intermediate filaments (cell structure)
• specific kinases for cell signaling
• other enzymes (caspase-activated DNAse)
FAS can bind to the FAS receptor
(trimerizer) → death domain binden aan
elkaar → procaspase 8 bind to each
other → caspase 8 activated →
apoptotic proteins
TNF-alfa can bind to one receptor →
uses not the FADD receptor, but the
TRADD receptor.
TRILL ligand bestaat ook.
these are result in activation of capsase 8
and than apoptosis.
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