Baruah B, Gabriel GJ, Akbashev MJ, Booher ME. 2013. Facile synthesis of silver nanoparticles stabilized by cationic polynorbornenes and their catalytic activity in 4-nitrophenol reduction. Langmuir 29(13):4225-34. ABSTRACT: We report the facile one-pot single-phase syntheses of silver nanoparticles stabilized by norbornene type cationic polymers. Silver nanoparticles (AgNPs) stabilized by polyguanidino oxanorbornenes (PG) at 5 and 25 kDa and polyamino oxanorbornenes (PA) at 3 and 15 kDa have been synthesized by the reduction of silver ions with NaBH 4 in aqueous solutions at ambient temperature. The four different silver nanoparticles have been characterized by UV−vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM) for their particle size distributions. Interestingly, PG stabilizes the silver nanoparticles better than PA as evident from our spectroscopic data. Furthermore, the AgNP-PG-5K (5K = 5 kDa) was found to serve as an effective catalyst for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH 4 . The reduction has a pseudo-first-order rate constant of 5.50 × 10 −3 s −1 and an activity parameter of 1375 s −1 g −1 , which is significantly higher than other systems reported in the literature.

Diverse cellular processes relevant to cancer progression are regulated by the acetylation status of proteins. Among such processes is chromatin remodeling via histone proteins, controlled by opposing histone deacetylase (HDAC) and histone acetyltransferase (HAT) enzymes. Histone deacetylase inhibitors (HDACi) show great promise in preclinical cancer models, but clinical trials treating solid tumors have failed to improve patient survival. This is due in part to an inability of HDACi to effectively accumulate in cancerous cells. To address this problem we designed HDACi with secondary pharmacophores to facilitate selective accumulation in malignant cells. We present the first example of HDACi compounds targeted to prostate tumors by equipping them with the additional ability to bind the androgen receptor (AR) with non-steroidal antiandrogen moieties. Leads among these new dual-acting molecules bind to the AR and halt AR transcriptional activity at lower concentrations than clinical antiandrogens. They inhibit key isoforms of HDAC with low nanomolar potency. Fluorescent microscopy reveals varying degrees of AR nuclear localization in response to these compounds that correlates with their HDAC activity. These biological properties translate into potent anticancer activity against hormone dependent (AR+) LNCaP and to a lesser extent against hormone independent (AR−) DU145 prostate cancer, while having greatly reduced toxicity in non-cancerous cells. This illustrates that engaging multiple biological targets with a single chemical probe can achieve both potent and cell-type selective responses.

Diverse cellular processes relevant to cancer progression are regulated by the acetylation status of proteins, such as chromatin remodeling via histone proteins, controlled by opposing histone deacetylase (HDAC) and histone acetyltransferase (HAT) enzymes. Histone deacetylase inhibitors (HDACi) show great promise in preclinical cancer models, but clinical trials for solid tumors have failed to improve patient survival. This is due in part to an inability of HDACi to effectively accumulate in cancerous cells. To address this problem we designed HDACi with secondary pharmacophores to facilitate selective enrichment in malignant cells. We present the first example of HDACi compounds targeted to prostate tumors by equipping them (via “click” chemistry) with the secondary ability to bind the androgen receptor (AR) with non-steroidal antiandrogen moieties. Leads among these new duel-acting molecules bind to the AR and halt AR transcriptional activity at lower concentrations than clinical antiandrogens. They inhibit key isoforms of HDAC with improved potency over clinically approved HDACi, SAHA. Fluorescent microscopy reveals varying degrees of AR nuclear localization in response to these compounds. These biological properties translate into anticancer activity against hormone independent (AR-) DU145 prostate cancer, and even more so against hormone dependent (AR+) LNCaP, while having greatly reduced toxicity in non-cancerous cells. These compounds illustrate a “smart bomb” approach towards achieving selective, safe, and potent cancer therapies. Citation Format: Berkley E. Gryder, Michelle J. Akbashev, Michael K. Rood, Paulette Dillard, Shafiq Khan, Adegboyega K. Oyelere. Selectively targeting prostate cancer with antiandrogen-equipped histone deacetylase inhibitors. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr B50.