A novel L-phenylalanine dipeptide inhibits prostate cancer cell proliferation by targeting TNFSF9.

In the present study, a series of novel L-phenylalanine dipeptides were designed and synthesized by a multi-step sequence of reactions, including carbodiimide-mediated condensation, hydrolysis, mixed anhydride condensation, and nucleophilic substitution. Among them, compound 7c exhibited potent antitumor activity against prostate cancer cell PC3 in vitro and in vivo via inducing apoptosis. We investigated the significantly differentially expressed proteins in the cells caused by the compound 7c to unravel the molecular mechanisms underlying the regulation of PCa cell growth, which indicated that 7c mainly regulated the protein expression of apoptosis-related transcription factors, including c-Jun, IL6, LAMB3, OSMR, STC1, OLR1, SDC4 and PLAU; and 7c also regulated the protein expression of inflammatory cytokines including IL6, CXCL8, TNFSF9, TNFRSF12A and OSMR, and the phosphorylation levels of RelA. The action target confirmed that TNFSF9 protein is the critical binding target of 7c. These findings suggested that 7c could regulate the apoptosis and inflammatory response related signaling pathways for the inhibition of the proliferation of PC3 cells, implying that 7c could be considered a promising therapeutic candidate for PCa therapy.