YO-01027 (DBZ) is a potent γ-secretase inhibitor.

γ-secretase (Notch):2.9 nM, γ-secretase (APPL):2.6 nM

YO-01027 interacts directly with theγ-secretase complex and targets the N-terminal Presenilin fragment. Increasing concentrations of YO-01027 administered to APPL- or Notch-expressing cells leads to the progressive accumulation of APPL CTF fragments and a decrease in NICD production in a strictly dose-dependent manner. [1] 10 μM of YO-01027 reduces breast cancer stem cells (BCSC) number and activity. [2] A recent research indicates YO-01027 impairs mucin protein MUC16 biosynthesis in a concentration-dependent manner in undifferentiated cells at both preconfluent and confluent stages through Notch inhibition, but not in postmitotic stratified cells. [3]

YO-01027, which is delivered 1 mg/mL by i.p. injection on the day of cell injection and every subsequent 3 days, YO-01027 significantly, decreases MCF7 but not MDA-MB-231 tumors and increases latency compared with control mice (18-28 days). YO-01027-treated MCF7 tumors that did form had significantly reduced tumor volumes. [2] Treatment of YO-01027 into C57BL/6 mice inhibits epithelial cell proliferation and induces goblet cell differentiation in intestinal adenomas in a dose-dependent manner. [4]

Pharmacological Inhibition of γ-secretase Activity: For YO-01027, pilot experiments are performed with different drug concentrations ranging from 0.1 nM to 250 nM to determine the effective linear range and maximal inhibition dose for YO-01027. YO-01027 is added at the required concentrations to the S2 cell medium upon induction of Notch or APPL expression, 6 hours before protein harvesting. For each sample, YO-01027 is also included at the corresponding concentration in the lysis buffer for protein extraction and immunoblot analysis.

Cells are resuspended at ≤1 × 106 in 100 μL sorting buffer (PBS containing 0.5% bovine serum albumin, 2 mM EDTA) and incubated with preconjugated primary antibodies BEREP4-FITC (1:10), CD44-APC (1:20), and CD24-PE (1:10) for 10 minutes at 4 °C. The cells are washed in PBS and centrifuged at 800 × g for 2 minutes. For analysis, cells are resuspended in 500 μL of sorting buffer and fluorescence is measured using FACSCalibur and analyzed using WinMIDI 2.8. For sorting, cells are resuspended in 1× HBSS after incubation with the primary antibodies. Cells are sorted, with HBSS as sheath fluid, at 16 p.s.i. using FACSAria. The CD24low cell population gated by FACS is the lowest quintile of CD24-positive cells plus all the CD24-negative cells.(Only for Reference)