20.109(F13): Mod 2 Day 7 HTS and Analysis
Introduction
Last time you set up a cell viability screen to evaluate the combination of an EGFR inhibitor and an inhibitor targeting a downstream pathway (PI3K/Akt, Ras/ErK, or STAT3). Today we will use a luminescence-based assay to quantify the extent of cell death within your culture. If the robot in the Koch Institute is cooperating (oh the perils of high technology!) we will depend on it to do all the work for us! Otherwise, we will employ a 96-well multichannel pipette to significantly cut down on our work -- giving us a different method to minimize our pipetting steps.
The cell viability assay that we will use is from Promega, Inc., and is called the CellTiter-Glo assay. The CellTiter-Glo reagent contains a recombinantly produced Luciferase that catalyzes the mono-oxygenation of beetle luciferan to oxyluciferan + light. The reaction requires Mg2+ and ATP -- and the source of ATP for the reaction is from your cells. Therefore, the extent of reaction (i.e. light generation) is related to the number of live cells within the culture. Promega reports that the reaction proceeds linearly within the range of 15 and > 50,000 cells. The doubling time of our SKOV3 cells is approximately 30 hrs, therefore our experiment will be safely within this range.
After completing the CellTiter-Glo assay you can follow the steps below to use provided Matlab code to calculate IC50 values for your Eroltinib + Inhibitor X combinations. You will pre-process the data using Excel and then import a properly formatted spreadsheet into Matlab for visualization and calculation.
Cell viability high throughput screen
The CellTiter-Glo reaction proceeds most effectively at room temperature. Therefore, your experimental plates were removed from the tissue culture incubator and allowed to equilibrate to room temperature at the beginning of class. The CellTiter-Glo reagents have also warmed to room temp.
The following steps are written for completing the assay on the benchtop. All of the steps are done in the same way when using the robot in the HTS facility -- but you don't have to do the pipetting!
- Use the Liquidator 96-well multi-channel pipettor to add 100 μL of CellTiter-Glo reagent to every well in your experimental assay plate.
- Place the plate on the rotating platform in the chemical hood for 2 min.
- Remove the plate and place on your benchtop for 18 min.
- Obtain a black-walled, white well 96-well assay plate from the front bench.
- After 10 min, use a multi-channel pipettor to first mix and then transfer 100 μL of each well to the black plate.
- Change your pipette tips with each addition -- perform this transfer column-wise. This will make for 12 distinct pipetting steps -- you will need one box of pipette tips for this step.
- Measure the luminescent output from each well using the SpectraMax L luminometer collecting light from each well for 1 sec.
- The teaching staff will go upstairs with you to use the luminometer.
