Targeted protein degradation using small molecules is a novel strategy for drug development. We have developed hybrid molecules named specific and nongenetic inhibitor of apoptosis protein [IAP]-dependent protein erasers (SNIPERs) that recruit IAP ubiquitin ligases to degrade target proteins. Here, we show novel SNIPERs capable of inducing proteasomal degradation of the androgen receptor (AR). Through derivatization of the SNIPER(AR) molecule at the AR ligand and IAP ligand and linker, we developed 42a (SNIPER(AR)-51), which shows effective protein knockdown activity against AR. Consistent with the degradation of the AR protein, 42a inhibits AR-mediated gene expression and proliferation of androgen-dependent prostate cancer cells. In addition, 42a efficiently induces caspase activation and apoptosis in prostate cancer cells, which was not observed in the cells treated with AR antagonists. These results suggest that SNIPER(AR)s could be leads for an anticancer drug against prostate cancers that exhibit AR-dependent proliferation.

Deamination of DNA bases can create missense mutations predisposing humans to cancer and also interfere with other basic molecular genetic processes; this deamination generates deoxyinosine from deoxyadenosine. In Escherichia coli, the highly conserved endonuclease V is involved in alternative excision repair that removes deoxyinosine from DNA. However, its exact activities and roles in humans are unknown. Here we characterize the FLJ35220 protein, the human homologue of E. coli endonuclease V, hEndoV as a ribonuclease specific for inosine-containing RNA. hEndoV preferentially binds to RNA and efficiently hydrolyses the second phosphodiester bond located 3′ to the inosine in unpaired inosine-containing ssRNA regions in dsRNA. It localizes to the cytoplasm in cells. The ribonuclease activity is promoted by Tudor staphylococcal nuclease and detected on inosine-containing dsRNA created by the action of adenosine deaminases acting on RNA. These results demonstrate that hEndoV controls the fate of inosine-containing RNA in humans.

RESULTS Structure Table 1. (Fig. 3). Degradation of cIAP1 and XIAP by SNIPER(ER)s.As observed in studies of many IAP antagonists, SNIPERs in our study rapidly ( Fig. 2a and 3b), consistent with their increased binding affinities for cIAP1 (Table 1). Further, these SNIPER(ER)s reduced XIAP expression in MCF-7 cells after 48 h in a more potent fashion than SNIPER(ER)-87( Fig. 2a). The reduction of XIAP by SNIPER(ER)s was prominent in T47D cells after 48 h, but was weak after 4 h of exposure (Fig. 3b). The difference in the degradation pattern between cIAP1 and XIAP suggests that these IAPs are degraded through a different mechanism, as discussed below. XIAP is required for the ERα degradation by SNIPER(ER)s.We previously reported that XIAP is In vivo protein knockdown activities and antitumor activities of SNIPER(ER)sWe measured the metabolic stabilities of Development of potent SNIPER derivatives against ERα 9MCF-7 cells, but not in T47D cells (Fig. 6).The role of IAPs in cancer cell survival has been suggested in many papers (32,(42)(43)(44)(45)58 Measurement of binding affinities of ERα and IAPsThe bindings between test compounds and cIAP1, cIAP2 or XIAP were determined by

Four kinds of folded structures are formed upon the metal complexation of a bis(N(2)O(2)) ligand in which two oxime-type N(2)O(2) chelate ligands are connected by a flexible diethyleneoxy linker. The N(2)O(2) coordination sites are intended for d-block transition-metal ions, and the diethyleneoxy linker can interact with hard metal cations. Meso double helical, folded Omega-shaped, S-shaped helical, and single helical structures were formed depending on the metal combination. The difference in the affinity to metal cations resulted in variation of the folding modes and enabled the structural conversion between the folded structures.

By utilizing the preferential enrichment (PE) technique, we achieved an improved enantiomeric resolution of DL-leucine (Leu) using a 1:1 cocrystal (DL-) of DL-Leu and oxalic acid. The crystal structure analysis of DL- indicated the occurrence of a novel type of phase transition and subsequent preferential redissolution of one enantiomer from the resulting crystals into solution.