SBFI Inhibitors Reprogram Transcriptomic Landscape of Prostate Cancer Cells Leading to Cell Death

Background: Prostate cancer (PCa) remains the second leading cause of cancer-related deaths in men in the United States. Fatty acid-binding protein 5 (FABP5), a member of a class of intracellular lipid transporters, promotes PCa progression via enhanced lipid metabolism and trafficking of lipid ligands. Previous work from our group has demonstrated that small-molecule FABP5 inhibitors based on the truxillic-acid monoester scaffold reduce PCa growth. Methods: Here, we assessed the effect of third-generation FABP5 inhibitors on the PCa cell cycle, proliferation, apoptosis, signaling pathway activity, and transcriptomic landscape. Results: We demonstrate that the third-generation FABP5 inhibitor SBFI-1143 significantly inhibits the viability of PCa cells by arresting them at the G0/G1 and G2/M phases of the cell cycle, inducing apoptosis, and promoting cell death. Strikingly, SBFI-1143 efficiently inhibited the growth of PCa spheroids compared to its predecessor, SBFI-103. RNA-seq and Gene Set Enrichment Analysis demonstrated that SBFI-1143 more effectively suppressed pathways involved in cell cycle progression, cell cycle division, and chromosome organization while upregulating genes associated with endoplasmic reticulum stress, responses to incorrectly folded proteins, and regulating apoptosis, compared to SBFI-103. Notably, SBFI-1143 treatment downregulated genes associated with the subpopulation of PCa cells characterized by a lineage plasticity-related signature, related to trans-differentiation, recurrence, and poor cancer prognosis. Conclusions: Our findings demonstrate that SBFI-1143 significantly alters the transcriptomic landscape of prostate cancer and may serve as a potentially effective therapeutic option for this disease.