CEM21 Cytotoxicity Assay Measured in Cell-Based System Using Plate Reader - 7013-03_Inhibitor_Dose_DryPowder_Activity
In the fusion assays, a reduction in luciferase signal could be a direct result of cell cytotoxicity and have nothing to do with inhibition of viral fusion. To discard such false positives, the cytotoxicity of each positive hit towards CEM cells will be evaluated using the CellTiter-Glo reagent. Cells will be treated with compounds at multiple doses for 24 hours. Cell viability will be measured using CellTiterGlo (Promega) which measures cellular ATP levels as a surrogate marker of cell viability/proliferation. ..more
BioActive Compounds: 9
Keywords: CEM, lymphoblast cell line, cytotoxicity, luciferase, CellTiter-Glo
In the fusion assays, a reduction in luciferase signal could be a direct result of cell cytotoxicity and have nothing to do with inhibition of viral fusion. To discard such false positives, the cytotoxicity of each positive hit towards CEM cells will be evaluated using the CellTiter-Glo reagent. Cells will be treated with compounds at multiple doses for 24 hours. Cell viability will be measured using CellTiterGlo (Promega) which measures cellular ATP levels as a surrogate marker of cell viability/proliferation.
Expected Outcome: A dose-dependent decrease in luciferase signal will suggest that a compound is cytotoxic and will not be a viable probe candidate.
1.Grow CEM21 cells in RPMI induction medium. Split 1:3 or 1:4 for passing.
2.Day 1: Collect CEM21 cells in conical tubes. Spin down the cells at ~1200 rpm for 5 minutes & re-suspend in phenol red free RPMI induction medium (with Puromycin).
3.Count cells, adjust to 3x10;5 cells/mL & seed 3,000 cells per well in 30 microl of RPMI (no Phenol Red) induction medium in Corning 8867BC white 384 well plates.
4.Day 2: Pin transfer 100 nL of compounds to the plate. Incubate the plate 37 degrees C overnight.
5.Day 3: Add 20 microl of room temperature CellTiter-Glo (Promega). Wait 10 minutes & read luminescence with standard luminescence settings on a Perkin-Elmer EnVision plate reader.
RPMI induction medium (500 mL):
RPMI (-Phenol red)###443 mL
Tet approved HI-FBS###50 mL
Puromycin (10 mg/mL)###50 microL
.All cells have to be in exponential growth phase. CEM21 cells are split 1:10 every 3 days. Cells should not be allowed to overgrow in the flasks.
.All incubations are done at 37 degrees C in the presence of 5% CO2.
.Cells should be propagated for no more than 30 passages or 3 months whichever is sooner.
PRESENCE OF CONTROLS: Neutral control wells (NC; n=104) were included on every plate.
EXPECTED OUTCOME: Active compounds result in decreasing readout signal.
ACTIVE CONCENTRATION LIMIT:
For each sample, the highest valid tested concentration (Max_Concentration) was determined and the active concentration limit (AC_limit) was set to equal (2)(Max_Concentration).
The raw signals of the plate wells were normalized using the 'Neutral Controls' method in Genedata Assay Analyzer (v10.0.2):
The median raw signal of the intraplate neutral controls (NC) is set to a normalized activity value of 0.
A normalized activity value of 100 is defined as (2)(NC).
A normalized activity value of -50 is defined as (0.5)(NC).
Experimental wells values were scaled to this range.
PATTERN CORRECTION: No plate pattern correction algorithm from Genedata Condoseo (v.10.0.2) was applied.
MEASUREMENT USED TO DETERMINE ACTIVE CONCENTRATION (AC): AC50
AC values were calculated using the curve fitting strategies in Genedata Screener Condoseo (7.0.3).
AC values were calculated up to the active concentration limit described for each sample.
pAC was set to equal -1*log10(AC)
Activity_Outcome = 1 (inactive) when:
a) compound shows activity but in a direction opposite to the expected outcome
in these cases, values describing curve fitting parameters (Sinf, S0, Hill Slope, log_AC50, log_AC50_SE) are set to null
b) curve fit is constant where activity is > -30% and < 30% at all tested concentrations, or
c) AC > AC_limit
Activity_Outcome = 2 (active) when:
AC <= AC_limit
Activity_Outcome = 3 (inconclusive) when:
a) Curve fitting strategy resulted in a constant fit with activity >= -70% but <= -30%, or
b) The fit was deemed not valid due to poor fit quality.
If PUBCHEM_ACTIVITY_OUTCOME = 1 (inactive) or 3 (inconclusive),
then PUBCHEM_ACTIVITY_SCORE = 0
If PUBCHEM_ACTIVITY_OUTCOME = 2 (active)
then PUBCHEM_ACTIVITY_SCORE = (10)(pAC)
Scores relate to AC in this manner:
120 = 1 pM
90 = 1 nM
60 = 1 uM
30 = 1 mM
0 = 1 M
When the active concentration (AC) is calculated to be greater than the highest valid tested concentration (Max_Concentration), the PUBCHEM_ACTIVITY_SCORE is calculated using Max_Concentration as the basis.
When the active concentration (AC) is calculated to be less than the lowest tested concentration, the PUBCHEM_ACTIVITY_SCORE is calculated using the lowest tested concentration as the basis.
The individual dose data point columns ('Activity_at_xxuM') reported here represent the median of valid (unmasked) replicate observations at each concentration. These values are the inputs to a curve fitting algorithm.
All other data columns represent values which are derived during the curve fitting algorithm; this may sometimes include automatic further masking of some replicate data points.
Occasionally this results in perceived inconsistencies: for example, between the derived 'Maximal_Activity' and the apparent most active data point.
Categorized Comment - additional comments and annotations
* Activity Concentration. ** Test Concentration.
Data Table (Concise)