Inhibitors of Epstein-Barr LMP1 inducible NF-kappaB luciferase reporter Measured in Cell-Based System Using Plate Reader - 2122-01_Inhibitor_SinglePoint_HTS_Activity
Keywords: NF-kappaB, Epstein-Barr Virus, inhibitor, LMP1, Latent Membrane Protein 1, luciferase reporter, TES1, TES2 ..more
BioActive Compounds: 2373
Keywords: NF-kappaB, Epstein-Barr Virus, inhibitor, LMP1, Latent Membrane Protein 1, luciferase reporter, TES1, TES2
Assay Overview: Epstein-Barr Virus is a ubiquitous Herpesvirus that is an important cause of Hodgkin's Disease, other Lymphoproliferative Diseases, and Nasopharyngeal Carcinoma. EBV infection mimics NF-kB hyperactivation states present in many malignancies. The EBV oncoprotein LMP1 constitutively activates both canonical and noncanonical NF-kB pathways in a ligand-independent fashion. LMP1 is expressed in most EBV-associated lymphoproliferative and epithelial malignancies. LMP1 activates NF-kB via two cytoplasmic signaling domains. The membrane proximal "TES1" domain activates a non-canonical NF-kappaB pathway, while the membrane distal "TES2" domain activates canonical NF-kappaB.
The primary screen uses a stably transfected HEK293 cell line with a doxycycline & 4-hydroxytamoxifen inducible LMP1 TES2 construct and a NF-kappaB luciferase reporter. Induction of the system will activate the NF-kappaB pathway and result in expression of the luciferase reporter gene. Inhibitors of the the pathway will block expression of the reporter construct.
Expected Outcome: Inhibitors of the LMP1 pathway will show a reduction in luminescence measured by a commercial luciferase kit (SteadyGlo, Promega.) Later assays will determine whether this loss of signal is due to inhibition of the pathway of interest or due to off-target or general toxicity effects.
LMP-1 Screening Protocol
(Luciferase reporter assay)
Day 0, cell grown in HyperFlask (Corning) to 95% confluence to yield 273 Million (TrypLE phenol free) and resuspended to dispensing at 150,000 cells / mL of phenol free DMEM
Day 1, plate cells 3000 per well in 20 uL media (phenol red free DMEM/10% Tet Free FBS/Pen/Strep/L-Glutamine); incubate in standard TC conditions (5% CO2; 95% humidity, 37C) for 24 hours.
Day 2, add 10 uL per well of stimulant (3ug/mL doxycycline and 3uM 4-hydroxytamxoifen in phenol free DMEM medium) with a Combi multidrop (Thermo);
add 100 nL 3.75 mM compound library into 30 uL assay volume in white, opaque Corning 8867 barcoded 384 well plates using a pin tool (HiRes Biosolutions). Final compound library concentration was 12.5 uM. MG132 (Calbiochem 474790), a proteasome inhibitor that blocks degradation of NF-kappaB inhibitor Ikappa-Balpha, was added to positive control wells to a final concentration of 16.7 uM.
Incubate 16 hours at 37 degrees C in Liconic incubator, 95% humidity 5% CO2.
Day 3, remove plate from incubator to cool for 15 minutes to room temperature; add 20 uL 50% Promega Steady glo (diluted 1:1 with PBS pH 7.4) with Thermo Combi.
Incubate at RT for 5 minutes.
Read on Perkin-Elmer Envision with US LUM settings for 0.1 sec per well.
PRESENCE OF CONTROLS: Neutral control wells (NC) and positive control wells (PC) were included on every plate.
EXPECTED OUTCOME: Active compounds result in decreasing readout signal.
The raw signals of the plate wells were normalized using the 'Neutral Controls Minus Inhibitors' method in Genedata Assay Analyzer (v7.0.3):
The median raw signal of the intraplate neutral control wells was set to a normalized activity value of 0.
The median raw signal of the intraplate positive control wells was set to a normalized activity value of -100.
Experimental wells values were scaled to this range.
PATTERN CORRECTION: The plate pattern correction algorithm 'Runwise Pattern (Multiplicative)' in Genedata (v7.0.3) was applied to the normalized plate data.
This was set as equal to -1 * the mean of the normalized and corrected sample replicate activities, rounded to the nearest integer .
The minimum PUBCHEM_ACTIVITY_SCORE required for a compound to be called a hit (the activity threshold, or AT) was set at 40.
PERCENTAGE OF ACTIVE REPLICATES:
For each sample, the percentage of replicates (PCT_ACTIVE_REP) which had activity scores >= AT was determined.
The minimum percentage of replicates required for a compound to be called a hit (PAR_T) was set at 100.
Samples passing BOTH threshold criteria were assigned an outcome of 2 (active):
PUBCHEM_ACTIVITY_SCORE >= AT, and PCT_ACTIVE_REP >= PAR_T
Samples passing NEITHER threshold criteria were assigned an outcome of 1 (inactive):
PUBCHEM_ACTIVITY_SCORE < AT, and PCT_ACTIVE_REP < PAR_T
Samples passing AT only were assigned an outcome of 3 (inconclusive) :
PUBCHEM_ACTIVITY_SCORE >= AT, and PCT_ACTIVE_REP < PAR_T
Categorized Comment - additional comments and annotations
** Test Concentration.
Data Table (Concise)