STK33 Kinase Inhibitor BRD-8899 Has No Effect
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Transcript STK33 Kinase Inhibitor BRD-8899 Has No Effect
STK33 KINASE INHIBITOR BRD-8899 HAS
NO EFFECT ON KRAS-DEPENDENT
CANCER CELL VIABILITY
Gloria Phuong Le
Biochemistry 2
What is the
function of the
RAS protein
family?
RAS PROTEIN FAMILY
Published in: Julian Downward; Nature 2002, 3, 11-22.
DOI: 10.1038/nrc969
Copyright © 2002 Nature Publishing Group
RAS PROTEIN FAMILY
RAS proteins have the ability to regulate
cell growth. They were discovered as
proteins encoded by retroviral oncogenes
that had been hijacked from the host
genome by the Kirsten and Harvey rat
sarcoma viruses.
RAS PROTEIN FAMILY
Three
members: HRAS, KRAS, and NRAS
Only KRAS is expressed in all cell types
Post-translational modification is required for
activation
RAS proteins are found to be activated in human
tumors. Activated RAS leads to the deregulation
of:
Tumor cell growth
Programmed cell death and invasiveness
The inability to induce new blood-vessel formation
RAS PROTEIN FAMILY
Published in: Julian Downward; Nature 2002, 3, 11-22.
DOI: 10.1038/nrc969
Copyright © 2002 Nature Publishing Group
EARLY ATTEMPTS TO TARGET
UPSTREAM RAS SIGNALING
PATHWAY
Two approaches:
Farnesyltransferase inhibitor
Target the synthesis of RAS
using antisense oligonucleotides
RAS PROTEIN FAMILY
Published in: Julian Downward; Nature 2002, 3, 11-22.
DOI: 10.1038/nrc969
Copyright © 2002 Nature Publishing Group
UPSTREAM SIGNALING TARGET
The first: FT-inhibitors
KRAS and NRAS can still be geranylgeranylated
as a ‘rescue’ process
KRAS is the most commonly mutated RAS
isoform in human tumors
Second: antisense oligonucleotide target
HRAS target (phase II no efficacy against lung
carcinoma)
KRAS is not an approachable target (ubiquitous)
Both methods failed!
SO FAR…
RAS
upstream signaling is non-druggable
Kinase inhibitors of RAS effector
pathways is a promising approach
CANCER CELLS OVERVIEW…
Cancer cells are blocked from normal cell
proliferation. They display low-level of cell-death
signals
They may develop secondary dependencies on
non-oncogenic genes and other substances not
commonly found in normal cells.
This is the basis of synthetic lethal approach
What is synthetic lethal
approach?
SYNTHETIC LETHAL APPROACH
Because
of cancer cell secondary
dependencies on “strange” substances
not commonly found in normal cells
Alteration of these genes results in
selective apoptosis of cancer cells
This definition is adapted from: Scholl et al. ; Cell 2009, 137, 821-834.
DOI: 10.1016/j.cell.2009.03.017
Copyright © 2009 Elsevier Inc.
WHAT IS SYNTHETIC LETHALITY
Mutations
in 2 or more genes causes cells
death whereas mutation in just one leaves
cell viable
Used
results from a previous experiment
that implicated STK33 kinase knock down
with KRAS dependent cancer death
KRAS MUTATION
The
most commonly mutated human
oncogene.
What
is an oncogene
Implicated
in 30 % lung, 50% colon, and
90% pancreas adenocarcinoma.
HIGH THROUGHPUT SCREENING
Run
millions of experiments at the same
Use
a micro titer plate.
time
Plate
Well
arranged in 8 by 12 9mm well
contain DMSO and other reagents
Controlled
manually or by robots
HIGH THROUGHPUT SCREENING
Wells used in high throughput screening
STK33 HIGH THROUGHPUT SCREENING
27,500
102
95
compounds initially used
primary hits
replicate hits
Fasudil
finally chosen due to its low micro
molar potency and selective kinase
inhibition.
WHAT IS FASUDIL
Rho-associated
protien kinase (ROCK)
inhibitor.
ROCK
is a kinase that belongs to the
serine/threonine kinase family.
Also
a vasodilator use to treat cerebral
vasospasm and improve cognitive decline
in stroke victims amongst other things.
FASUDIL BRD7446 AND BRD8899
FASUDIL
BRD 8899
After
a few manipulations BRD 8899 was
produced
Had
200 fold potency compared to BRD
7446
Ready
for in vivo testing.
Testing
fails
.
WHY