Inducing paraptosis, a nonapoptotic form of cell death,
has great
therapeutic potential in cancer therapy, especially for drug-resistant
tumors. However, the specific molecular target(s) that trigger paraptosis
have not yet been deciphered yet. Herein, by using activity-based
protein profiling, we identified the GDP-dissociation inhibitor beta
(GDI2) as a manipulable target for inducing paraptosis and uncovered
benzo[a]quinolizidine BQZ-485 as a potent inhibitor
of GDI2 through the interaction with Tyr245. Comprehensive target
validation revealed that BQZ-485 disrupts the intrinsic GDI2-Rab1A
interaction, thereby abolishing vesicular transport from the endoplasmic
reticulum (ER) to the Golgi apparatus and initiating subsequent paraptosis
events including ER dilation and fusion, ER stress, the unfolded protein
response, and cytoplasmic vacuolization. Based on the structure of
BQZ-485, we created a small benzo[a]quinolizidine
library by click chemistry and discovered more potent GDI2 inhibitors
using a NanoLuc-based screening platform. Leveraging the engagement
of BQZ-485 with GDI2, we developed a selective GDI2 degrader. The
optimized inhibitor (+)-37 and degrader 21 described in this study exhibited excellent in vivo antitumor activity in two GDI2-overexpressing pancreatic xenograft
models, including an AsPc-1 solid tumor model and a transplanted human
PDAC tumor model. Altogether, our findings provide a promising strategy
for targeting GDI2 for paraptosis in the treatment of pancreatic cancers,
and these lead compounds could be further optimized to be effective
chemotherapeutics