PSP205, a Novel Phenyl Sulfonyl Piperidine, Induces Apoptotic Cell Death in Colon Cancer by Modulating Coat Protein Complex-Mediated Vesicle Trafficking

The endoplasmic reticulum (ER) stress and autophagic pathways offer attractive targets for the development of new cancer drugs. Here, we identified a novel phenyl sulfonyl piperidine, PSP205, that induces prolonged ER-stress-mediated autophagy and apoptosis in colon cancer cells. Transcriptome analysis of cells exposed to PSP205 unveiled transcriptional upregulation of genes associated with the ER stress response or unfolded protein response (UPR), in addition to vesicle transport. Among the top upregulated genes, DNAJB9, XBP1, PDIA4, HSPA5, SEC24D, and SEC11C are implicated in ER stress. Gene set enrichment analysis revealed the enrichment of gene sets involved in the UPR, mTORC1 signaling, hypoxia, the P53 pathway, apoptosis, and the ER-Golgi-vesicle-mediated transport pathway. Mechanistic studies showed that PSP205 acts on the IRE1-TRAF2-JNK pathway to modulate autophagic flux, leading to macroautophagy, ER-phagy, and deformation of Golgi. Our study also demonstrated that PSP205 decreases the expression of the COPI coat complex subunit beta 2 (COPB2) in the presence of COPB2 siRNA. Furthermore, PSP205 synergistically killed colon cancer cells in combination with proteasome and topoisomerase inhibitors. Cumulatively, our findings suggest that PSP205 targets cancer cells via a novel mechanism, specifically by decreasing the level of COPB2, which has not been extensively studied in the context of cancer therapy development and warrants further investigation.