GSK126 suppressed proliferation of MC38 colorectal cancer cells over 48 hours in a concentration-dependent manner, as measured by normalized cell confluence. These micromolar cellular exposures are distinct from the biochemical IC50. [2]
In a six-day endometrial tumor-model screen, GSK126 showed higher residual-viability AUC than bortezomib or panobinostat in REME9 and REME16 organoids and AN3 CA and RL95-2 cells, indicating weaker growth inhibition within that screen. Exact GSK126 potency was not extracted, and the paper gives inconsistent lower concentration bounds. [3]
Binding of GSK126 to engineered human PRC2
Biochemical assay · Engineered minimal human EZH2–SUZ12(VEFS)/EED complex; crystallized EZH2 has deletions and an inadvertently introduced W594R mutation. [1]
The human co-crystal model places GSK126 between the SET and SAL regions of EZH2. Its pyridone group partially overlaps the cofactor-binding site. Terminal portions of the ligand are incompletely resolved.
Literature-Reported Treatment Conditions
- Treatment concentration
- Fivefold molar excess of GSK126 for crystal soaking.
- Exposure duration
- 2-hour crystal soak
- Method
- X-ray crystallography of the engineered human PRC2–GSK126 complex (PDB 5WG6).
- Reported limits
- Absolute conformations of ligand terminal regions remain ambiguous; supplier and precise chemical form are not specified in the read text.
Methods and source locations
Compound reported in the paper: GSK126; Compound label in the paper: GSK126
Evidence concerns the named GSK126 material in the stated experiment; no salt conversion or current Adooq lot equivalence is inferred.
Figure 1a; Figure 2b,c and caption; Results Structures of human and ctPRC2 bound to GSK126; Crystallization; Structure Determination and Refinement; SI Figure S2a and Table 1
GSK126 location in the human PRC2 co-crystal: Crystallography and alignment with the human PRC2/SAH structure. — Figure 2b,c; Results Structures of human and ctPRC2 bound to GSK126; Structure Determination and Refinement
Inhibition of minimal human PRC2 methyltransferase activity
Biochemical assay · Minimal human PRC2 containing full-length EZH2 fused to SUZ12(VEFS), together with EED; H3K27me0 peptide substrate. [1]
GSK126 inhibited methyltransferase activity of the minimal human PRC2 preparation. The reported value is an assay IC50, not a binding constant or a cellular treatment concentration.
Literature-Reported Treatment Conditions
- Treatment concentration
- GSK126 titration with at least eight points; 50 nM human PRC2, 1 µM H3K27me0 peptide and 5 µM SAM.
- Exposure duration
- 1 hour at 30 °C
- Method
- Radiometric methyltransferase assay; scintillation counting in disintegrations per minute.
- Vehicle
- 2% DMSO final
- Reported limits
- Individual GSK126 titration concentrations are not tabulated in the read Methods. The sequence of the enzymatic construct is not fully specified; do not equate it with the engineered crystallographic construct or assert a native wild-type potency.
Methods and source locations
Compound reported in the paper: GSK126; Compound label in the paper: GSK126
Evidence concerns the named GSK126 material in the stated experiment; no salt conversion or current Adooq lot equivalence is inferred.
Figure 3b, left plot and caption; Results Comparison of the inhibition of human and ctPRC2 by GSK126; Protein Expression and Purification; IC50 Analysis; SI Figure S2b
Inhibition of human PRC2-mediated peptide methylation: Figure 3b label; fit of log(inhibitor) versus response. Points measured in duplicate; error bars are SD of two replicates. Background control contained enzyme without peptide. — Figure 3b, left plot and caption; IC50 Analysis
Six-day GSK126 screening in endometrial tumor models
Cell-based study · Endometrial cancer-derived F-PDOs REME9 and REME16, compared with AN3 CA and RL95-2 cell lines in a 384-well growth-inhibition screen. [3]
The displayed screen shows higher viability AUC for GSK126 than for bortezomib or panobinostat in all four models, consistent with weaker growth inhibition under this assay. No exact GSK126 AUC or IC50 is extracted.
Literature-Reported Treatment Conditions
- Treatment concentration
- Upper tested concentration 20 µM; lower concentration bound differs between Methods and Figure 6 caption.
- Exposure duration
- 144 hours after drug addition
- Method
- ATP-based CellTiter-Glo 3D viability assay, normalized against vehicle; dose-response AUC calculated using Morphit.
- Vehicle
- DMSO; general assay Methods specify a maximum of 0.1%.
- Reported limits
- 384-well Methods state 1.0 nM–20 µM (ten serial dilutions), whereas Figure 6 caption states 0.1–20 µM. This discrepancy remains unresolved. Exact GSK126 AUC/IC50 and whether triplicates are biological or technical are not specified in the read material.
Methods and source locations
Compound reported in the paper: GSK126; Compound label in the paper: GSK126
Evidence concerns the named GSK126 material in the stated experiment; no salt conversion or current Adooq lot equivalence is inferred.
Table II, GSK126 row; Figure 6 and caption; Growth inhibition assays using multi-well plates; Results Evaluation of anticancer agents using F-PDOs
Growth-inhibition screening response across REME9, REME16, AN3 CA and RL95-2: Figure 6 bar comparison; means of triplicate experiments. Higher residual-viability AUC is interpreted as weaker growth inhibition within the displayed screen. — Figure 6, GSK126/bortezomib/panobinostat rows and caption; Growth inhibition assays using multi-well plates
GSK126 suppresses MC38 monolayer proliferation
Cell-based study · Mouse MC38 colorectal cancer cells in 2D monolayer culture. [2]
GSK126 reduced the increase in normalized cell confluence over 48 hours in a concentration-dependent pattern. This phenotypic endpoint does not itself establish that the growth response is exclusively mediated by EZH2.
Literature-Reported Treatment Conditions
- Treatment concentration
- 9, 15.9, 21, 28 and 50 µM GSK126, as labeled in Figure 1c.
- Exposure duration
- 48 hours; imaging every 4 hours
- Method
- Incucyte live-cell imaging; phase area confluence normalized to time zero.
- Vehicle
- DMSO, final concentration <0.1% (v/v); control cells kept with DMSO.
- Reported limits
- No exact endpoint confluence values or proliferation IC50 are extracted. The Methods describe means based on 3 × 3 wells per condition; Figure 1 caption states three independent experiments.
Methods and source locations
Compound reported in the paper: GSK126; Compound label in the paper: GSK126
Evidence concerns the named GSK126 material in the stated experiment; no salt conversion or current Adooq lot equivalence is inferred.
Figure 1c and caption; Cell Proliferation Assay; Cell Treatment; Cell Lines and Cell Culture
MC38 proliferation inferred from normalized phase area confluence: Incucyte imaging; means based on 3 × 3 wells per condition with standard error described in Cell Proliferation Assay. — Figure 1c and caption; Cell Proliferation Assay; Cell Treatment
