Signal Transducer and Activator of Transcription 3 (STAT3) is a transcription factor that mediates cellular responses to cytokines and growth factors, regulating genes involved in proliferation, survival, and immune responses. STAT3 is activated by phosphorylation at Tyr705, leading to dimerization, nuclear translocation, and DNA binding. STAT3 regulates expression of genes including c-MYC, cyclin D1, BCL-XL, and VEGF, promoting cell cycle progression and survival. Constitutive STAT3 activation is found in approximately 70% of tumors, where it drives oncogenesis and creates an immunosuppressive microenvironment. STAT3 inhibitors are being developed as cancer therapeutics to target tumor cells and restore anti-tumor immunity.
The AlphaLISA SureFire Ultra Human and Mouse Phospho-STAT3 (Ser727) is a sandwich immunoassay for the quantitative detection of phospho-STAT3 (Ser727) in cellular lysates, using Alpha Technology.
Formats:
The HV (high volume) kit contains reagents to run 100 wells in 96-well format, using a 60 μL reaction volume.
The 500-point kit contains enough reagents to run 500 wells in 384-well format, using a 20 μL reaction volume.
The 10,000-point kit contains enough reagents to run 10,000 wells in 384-well format, using a 20 μL reaction volume.
The 50,000-point kit contains enough reagents to run 50,000 wells in 384-well format, using a 20 μL reaction volume.
AlphaLISA SureFire Ultra kits are compatible with:
Cell and tissue lysates
Antibody modulators
Biotherapeutic antibodies
AlphaLISA SureFire Ultra kits can be used for:
Cellular kinase assays
Receptor activation studies
High-throughput screening for preclinical studies
Phospho-AlphaLISA SureFire Ultra assay principle
The Phospho-AlphaLISA SureFire Ultra assay measures a target protein when phosphorylated at a specific residue in a biological sample (e.g. cell lysate).
The assay uses two antibodies which recognize the phospho epitope and a distal epitope on the target protein. AlphaLISA assays require two bead types: Acceptor and Donor Beads. Acceptor Beads are coated with a proprietary CaptSure™ agent to specifically immobilize the assay specific antibody, labeled with a CaptSure tag. Donor Beads are coated with streptavidin to capture one of the detection antibodies, which is biotinylated. In the presence of phosphorylated protein, the two antibodies bring the Donor and Acceptor Beads in close proximity whereby the singlet oxygen transfers energy to excite the Acceptor Bead, allowing for the generation of a luminescent Alpha signal. The amount of light emission is directly proportional to the quantity of phosphoprotein present in the sample.
Phospho-AlphaLISA SureFire Ultra two-plate assay protocol
The two-plate protocol involves culturing and treating the cells in a 96-well plate before lysis, then transferring lysates into a 384-well OptiPlate™ plate before the addition of Phospho-AlphaLISA SureFire Ultra detection reagents. This protocol enables cell viability and confluence to be monitored. In addition, lysates from a single well can be used to measure multiple targets.
Phospho-AlphaLISA SureFire Ultra one-plate assay protocol
Detection of Phosphorylated target protein with AlphaLISA SureFire Ultra reagents can be performed in a single plate used for culturing, treatment, and lysis. No washing steps are required. This HTS designed protocol allows for miniaturization while maintaining robust AlphaLISA SureFire Ultra quality.
Induction of STAT3 phosphorylation in EGF treated cells
HeLa cells were seeded in a 96-well plate (20,000 cells/well) in complete medium and incubated overnight at 37°C, 5% CO2. The cells were starved in media containing 1% FBS for 20 hours then treated with increasing concentrations of EGF for 15 minutes.
After treatment, the cells were lysed with 200 µL of Lysis Buffer for 10 minutes at RT with shaking (350 rpm). STAT3 Phospho (Ser727) and Total levels were evaluated using respective AlphaLISA SureFire Ultra assays. For the detection step, 10 µL of cell lysate (approximately 2,000 cells) was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at RT. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.
As expected, EGF triggered a dose-dependent increase in the levels of Phospho (Ser727) while Total STAT3 levels remained unchanged.
Induction of STAT3 phosphorylation in IFNα treated cells
A549 and HeLa cells were seeded in a 96-well plate (20,000 cells/well) in complete medium and incubated overnight at 37°C, 5% CO2. The cells were starved in media containing 1% FBS for 20 hours then treated with increasing concentrations of IFNα for 30 minutes.
After treatment, the cells were lysed with 200 µL of Lysis Buffer for 10 minutes at RT with shaking (350 rpm). STAT3 Phospho (Ser727) and Total levels were evaluated using respective AlphaLISA SureFire Ultra assays. For the detection step, 10 µL of cell lysate (approximately 2,000 cells) was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at RT. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.
As expected, treatment with IFNα induced a dose-dependent increase in the levels of Phospho (Ser727) while Total STAT3 levels remained unchanged.
Induction of STAT3 phosphorylation in IL-6 treated cells
A431 cells were seeded in a 96-well plate (30,000 cells/well) in complete medium and incubated overnight at 37°C, 5% CO2. The cells were starved in medium containing 1% FBS for 20 hours then treated with increasing concentrations of IL-6 for 15 minutes.
After treatment, the cells were lysed with 200 µL of Lysis Buffer for 10 minutes at RT with shaking (350 rpm). STAT3 Phospho (Ser727) and Total levels were evaluated using respective AlphaLISA SureFire Ultra assays. For the detection step, 10 µL of cell lysate (approximately 3,000 cells) was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at RT. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.
As expected, IL-6 treatment induced a dose-dependent increase in the levels of Phospho (Ser727) while Total STAT3 levels remained unchanged.
Induction of STAT3 phosphorylation in PMA treated cells
A431 cells were seeded in a 96-well plate (30,000 cells/well) in complete medium and incubated overnight at 37°C, 5% CO2. The cells were starved in media containing 1% FBS for 20 hours then treated with increasing concentrations of PMA for 30 minutes.
After treatment, the cells were lysed with 200 µL of Lysis Buffer for 10 minutes at RT with shaking (350 rpm). STAT3 Phospho (Ser727) and Total levels were evaluated using respective AlphaLISA SureFire Ultra assays. For the detection step, 10 µL of cell lysate (approximately 3,000 cells) was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at RT. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.
As expected, PMA treatment induced a dose-dependent increase in the levels of Phospho (Ser727) while Total STAT3 levels remained unchanged.
Inhibition of STAT3 phosphorylation in Staurosporine treated cells
HeLa cells were seeded in a 96-well plate (20,000 cells/well) in complete medium and incubated overnight at 37°C, 5% CO2. The cells were starved in media containing 1% FBS for 20 hours then treated with 5 µM Staurosporine for 30 minutes.
After treatment, the cells were lysed with 200 µL of Lysis Buffer for 10 minutes at RT with shaking (350 rpm). STAT3 Phospho (Ser727) and Total levels were evaluated using respective AlphaLISA SureFire Ultra assays. For the detection step, 10 µL of cell lysate (approximately 2,000 cells) was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at RT. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.
As expected, Staurosporine decreased the levels of STAT3 Phospho (Ser727) while Total levels remained unchanged.
Assay sensitivity - cell lysate dilution
Cell lysate was prepared from A431 cells cultured to confluency in a T175 flasks, treated with 2 µg/mL EGF for 10 minutes and lysed in 5 mL of Lysis Buffer for 10 minutes at RT with shaking.
Lysate was serially diluted in Lysis Buffer and STAT3 Phospho (Ser727) levels were evaluated by AlphaLISA SureFire Ultra. For the detection step, 10 µL of lysate was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at room temperature. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.
Approximate number of cells per datapoint is indicated. The dotted line represents assay background. The assay can detect STAT3 Phospho (Ser727) down to 50 cells/datapoint.
