Manifestation of Novel Social Challenges of the European Union
in the Teaching Material of
Medical Biotechnology Master’s Programmes
at the University of Pécs and at the University of Debrecen
Identification number: TÁMOP-4.1.2-08/1/A-2009-0011
Manifestation of Novel Social Challenges of the European Union
in the Teaching Material of
Medical Biotechnology Master’s Programmes
at the University of Pécs and at the University of Debrecen
Identification number: TÁMOP-4.1.2-08/1/A-2009-0011
Zoltan Balajthy
Molecular Therapies- Lecture 12
CELL CYCLE AND
CANCER
TÁMOP-4.1.2-08/1/A-2009-0011
Learning objectives of chapter 12 and 13 . The purpose of this chapter is to describe the processes and
regulations of both cell cycle and cell death, explain the unregulated cell division, and to point out the
therapeutic intervention in cancer at molecular levels.
Topics in chapter 12.
12.1. Interpretation of cell cycle
Constitutive and Inducible Cell Cycle Kinase Inhibitors
12.2. Mitogen-activated Protein (MAP) Kinase Cascade
Transcriptional Events in G1 Phase of Cell-cycle
Mechanisms of Gene-suppression by the Retinoblastoma Protein
12.3. Biochemical Events of Cell-cycle – in M Phase
12.4. Cancer Causing Genes in Mitotic Signal Pathway
Proto-oncogenes and Oncogenes
12.5. Different Families of Receptor Tyrosine Kinases (RTK)
Proto-oncogenes are normal genes that can become oncogenes
12.6. Therapeutic Targets
Monoclonal antibodies and specific inhibitors
TÁMOP-4.1.2-08/1/A-2009-0011
12.1. The Functional Cell Cycle
The conventional cell cycle is modified to indicate :
- G1 activities, those preparatory
for S phase, may begin during
the previous cycle, concurrently
with G2 and mitotic events.
- early preparation for mitosis (G2)
Checkpoints
may overlap with S
controll
- exit from G1 into the G0 quiescent
state and reentry into the cycle
The critical points:
C (indicating competence), V (end of entry)
R (restriction point, end of progression)
TÁMOP-4.1.2-08/1/A-2009-0011
Cyclin-CDK Regulators of Cell-Cycle
START
G2/M
P27
cyclin D
CDK
G0
cyclin E
CDK
G1
cyclin B
CDK
cyclin A
CDK
S
START
APC
G2
G2/M
Metaphase - Anaphase
Methaphase
INTERPHASE
G1
M
Anaphase
MITOSIS
CYTOKINESIS
CDK:cyclin-dependent protein kinases, APC: anaphase promoting complex,
P27:cyclin-dependent protein kinases inhibitor,
TÁMOP-4.1.2-08/1/A-2009-0011
Constitutive and Inducible Cell Cycle Kinase Inhibitors
,
and
are
check points
at the „s”, „gm”,
and „m” stable states
DNA-damage
inducible
Constitutive
CKI
APC
, CDK1
CKIs
Constitutive
CKI
DNA damade,
starvation or
factor inducible
cell divison cycle: CDC,
cyclin-dependent protein kinases: CDK
cyclin-dependent protein kinases inhibitor: CDI
TÁMOP-4.1.2-08/1/A-2009-0011
12.1. Mitogen-activated Protein (MAP) Kinase Cascade
Incoming
signal
L
Fatty acid and farnesyl
modification of ras
Receptor
tyrosine kinase
ShcGRB2
SH3 SH3
SOS
RAS
GDP
GTP
Inactive
GDP
GAP
RAS
GTP
Active
Raf
target
Outgoing
signal
P
P
MEK
P P
Pi
P P
Incoming
signal
SOS: guanine nucleotide exchange factor
GAP: GTPase activating protein
ERK: extracellular signal-regulated kinases
RAF, MEK, ERK: protein kinase phosphorilation cascade
FOS: transcription factor
ERK
P P
ERK
P
Fos
P
TÁMOP-4.1.2-08/1/A-2009-0011
Transcriptional Events in G1 Phase of Cell-cycle
CDK inhibitors
Start of S phase
DNS replication
machinery
pozitív
erősítés
Dihydrofolate reductase
Thymidine kinase
Thymidilate synthase
DNA polymerase
CDK inhibitors
E2F: transcription factor E2F1
EGF: epidermal growth factor
CDK: cyclin-dependent protein kinase
Rb: retinoblastoma protein
D1, A, E: Cyclin D1, A és E
transzkripció
leállítás
DNS replication
machinery
CDK inhibitors
TÁMOP-4.1.2-08/1/A-2009-0011
Mechanisms of Gene-suppression by the Retinoblastoma Protein
Ac
Ac
HDAC
Ac
Rb
Ac
Ac
Off
E2F
HDAC
p
Cyclin E, A
G1 CDK
active
HAC
p
Rb
On
p
p
Ac
Ac
Pol II
TF
Ac
E2F
Ac
Ac
Ac
Ac
Active CDK2
Ac
Ac
Ac
Pol II
Ac
Cyclin E
Cyclin E, A
TÁMOP-4.1.2-08/1/A-2009-0011
11.3. Biochemical Events of Cell-cycle – in M Phase
M
G2
Inhibitory Stabilizing
CDC 25
P-ation P-ation
p p
T
Y
p
p
p
T
Y
T
CKI
CDK
Proteolytic
degradation
C
p
K
T
I
Y
cyclin B
p
T
Y
T
CDK
CDK
p
T
CDK
cyclin B
Active protein
kinase
p
C
y
kl
i
n
Inactive protein
kinase
Proteolytic
degradation
Substrats
Substrats
phosphatases
+
Histone H1
Lamin
Vimentin
caldesmon
Y
T
cyclin B
Substrats
p
APC
T
T
CDK
G1
Chromatin condensation
Cytoskeleton rearranged
Mitotic spindle formation
Nuclear membrane dissolved
Cell shape changes
p
TÁMOP-4.1.2-08/1/A-2009-0011
12.4. Cancer Causing Genes in Mitotic Signal Pathway
L
L
Receptor
tyrosine kinase
L
Receptor
ShcGRB2
SH3 SH3
SOS
G protein
RAS
GTP
Growths-stimulating pathway
RAF
GTP
GTP
G protein
Growths-inhibiting pathway
Protein kinases
phosphorilation cascade
Protein kinases
phosphorilation cascade
MEK
NUCLEUS
Transcription
factor (activator)
P
Fos
Transcription
factor (sucs as p53)
NUCLEUS
ERK
ERK
Gene expression
Gene expression
Defective or missing
transcription factor,
such as p53, can’t
activate transcription
Proteins that inhibit
the cell cycle
Proteins that stimulate
the cell cycle
Protein overexpressed
Protein absent
Effect of abnormalities
Cell cycle overstimulated
X
Cell cycle not inhibited
X
TÁMOP-4.1.2-08/1/A-2009-0011
Proto-oncogenes and Oncogenes
Proto-oncogenes code
for growth factors.
Mutation cause overproduction of growth factors.
Proto-oncogenes code
for growth factor
receptors.
Mutant receptor no
longer requires growth
factor binding.
Proto-oncogenes code
for transcription factors.
Factors always bind to
their target gene promotor.
Proto-oncogenes code
for proteins that
transmit external
stimuli for cell division.
Stimulation no longer
needed.
TÁMOP-4.1.2-08/1/A-2009-0011
Possible Biochemical Mechanisms of Protooncogene - oncogene
Conversion
- promoter insertion
- enhancer insertion
- chromosomal translocation
- gene amplification
- single point mutation or deletion
Out the 5 mechanisms described above, the first 4 involve an increase in
amount of the product of an oncogene due to increased transcription but no
alteration of the structure of the product of the oncogene. Thus it appears
that increased amounts of the product of an oncogene may be sufficient to
push a cell becoming malignant. The fifth mechanism, single point mutation,
involves a change in the structure of the product of the oncogene but not
necessarily any change in its amount. This implies that the presence of a
structurally abnormal key regulatory protein in a cell may be sufficient to tip
the scale toward malignancy.
TÁMOP-4.1.2-08/1/A-2009-0011
12.5. Different Families of Receptor Tyrosine Kinases (RTK) Recognize
a Diverse Set of Different Ligands
Extracellular Binding Domain
IGF-1
IGF-2
TGF-a
EGF
VEGF-A
VEGF-B
PDGF
Transmembrane
Lipophilic Segment
P
P
P
P
EGFR
(HER 2,3,4
Intracellular Protein
Tyrosine Kinase Domain
PDGFR
IGF-1R
VEGFR
Receptor Heterodimerization and Activation
None
HER2
P
P
P
P
EGFR/HER2
TÁMOP-4.1.2-08/1/A-2009-0011
Ligand Binding Activates RTKs
by Dimerization
Ligand
Receptor
Homodimerization
TGF-a
EGF
Ligand-binding Site
Extracellular
Domein
Cytosolic
Domein
EGFR-s
(HER3,4)
ATP
ADP
Kinase Catalytic
Site
P
P
P
P
EGFR
TÁMOP-4.1.2-08/1/A-2009-0011
Proto-oncogenes are Normal Genes That Can Become Oncogenes
HER2
EGFR
Proto-oncogene
receptor protein
Val
Plasma membrane
(Deletion)
Oncogenic
Mutation
(Val → Glu)
Activating mutations
in RTKs take several
forms but all lead to
ligand-independent
dimerization and thus
activation.
Glutamine
ErbB
Neu
Ligand-independent Receptoer Oncoprotein
TÁMOP-4.1.2-08/1/A-2009-0011
Neu, EGFR-targeting Methods
mAbs
Tyrosine kinase
inhibitors (TKI)
Toxin-induced
cell death
✝
✝
L
L
X X
TKI
L
X X
RNA interference
L
L
L
L
TKI
X
X
Signal
transductiom
Signal
transductiom
X
Cell death
Protein
synthesis
TÁMOP-4.1.2-08/1/A-2009-0011
Expression of HER2 Receptor on the Surface of Normal and Tumor Cells
Herceptin Binds to the HER2 Receptor on the Surface of Tumor Cells
Normal expression of
HER2 receptor
Herceptin attaches itself to HER2 receptor
Increased expression of
HER2 receptor
Herceptin flags the cancer cells for destruction
by the immune system
TÁMOP-4.1.2-08/1/A-2009-0011
12.6. Therapeutic Targets
1, blocking signalization on cell surface receptor
1
L
L
Receptor
tyrosine kinase
ShcGRB2
2, inhibition of TK activity of TKR
SH3 SH3
2
TKI
TKI
SOS
G protein
RAS
GTP
Growths-stimulating pathway
GTP
RAF
Protein kinases
phosphorilation cascade
3, inhibition of protein kinases phosphorilation cascade
MEK
NUCLEUS
Transcription
Transcription
factor
(activator)
factor
(sucs
as p53)
Rb
E2F
4, activation of growths-inhibiting pathway (Rb) or
restoration of p53 function
5, inhibition of angiogenesis
6, inhibition of methastasis
ERK
4
Gene expression
Gene expression
Proteins that stimulate
the cell cycle
In addition to the classical form of cancer treatment: like surgery,
chemotherapy and radiotherapy, there are new therapeutic targets
at molecular level against cancer cells.
Protein overexpressed
3
TÁMOP-4.1.2-08/1/A-2009-0011
Blocking of Oncoproteins of EGFR and Mitogen-activated Protein
Kinase Signalization via Monoclonal abs. and Specific Inhibitors
L
L
Ligand binding
blocked by antibodies
TKI
TKI
XP
XP
Fatty acid and farnesyl
modification of ras
Tyrosine kinase
inhibitor
RAS
GDP
Raf
Raf inhibitor
inactive
BAY 43-9006
inactive
MEK inhibitor
SH3 SH3
GRB2
SOS
MEK
Signal transduction
cascade blocked
Ras farnesyltransferase
Inhibitors (BMS-214662)
CI-1040
inactive
ERK
inactive
TKI: Tyrosine kinase inhibitor
SOS: guanine nucleotide exchange factor
GAP: GTPase activating protein
ERK: extracellular signal-regulated kinases
RAF, MEK, ERK: protein kinase
phosphorilation cascade
FOS: transcription factor
Fos
Gene activation and cell cycle
progression inhibited