No abstract

SummaryRegulation of prostate epithelial progenitor cells is important in prostate development and prostate diseases. Our previous study demonstrated a function of autocrine cholinergic signaling (ACS) in promoting prostate cancer growth and castration resistance. However, whether or not such ACS also plays a role in prostate development is unknown. Here, we report that ACS promoted the proliferation and inhibited the differentiation of prostate epithelial progenitor cells in organotypic cultures. These results were confirmed by ex vivo lineage tracing assays and in vivo renal capsule recombination assays. Moreover, we found that M3 cholinergic receptor (CHRM3) was upregulated in a large subset of benign prostatic hyperplasia (BPH) tissues compared with normal tissues. Activation of CHRM3 also promoted the proliferation of BPH cells. Together, our findings identify a role of ACS in maintaining prostate epithelial progenitor cells in the proliferating state, and blockade of ACS may have clinical implications for the management of BPH.

Hearing loss resulting from hair cell degeneration is a common disease that affects millions of people worldwide. Strategies to overcome the apparent irreversible hair cell loss in mammals become paramount for hearing protection. Here we reported that, by using a well-established gentamicin-induced hair cell loss model in vitro, adjudin, a multi-functional small molecule drug, protected cochlear hair cells from gentamicin damage. Immunohistochemistry, Western blotting and quantitative RT-PCR analyses revealed that adjudin exerted its otoprotective effects by up-regulating the level of Sirt3, a member of Sirtuin family protein located in mitochondria, which regulates reactive oxygen species (ROS) production in cochlear cells and inhibits the production of ROS and apoptotic cells induced by gentamicin. Sirt3 silencing experiments confirmed that Sirt3-ROS signaling axis mediated hair cell protection against gentamicin by adjudin, at least in part. Furthermore, adjudin's otoprotection effects were also observed in an in vivo gentamicin-injured animal model. Taken together, these findings identify adjudin as a novel otoprotective small molecule via elevating Sirt3 levels and Sirt3 may be of therapeutic value in hair cell protection from ototoxic insults.

SIRT3 is involved in aging-related diseases including cancer, but its role in prostate cancer and detailed regulatory function are not known. We found that SIRT3 was moderately down-regulated in prostate carcinomas. Overexpression of SIRT3 by lentiviral transfection inhibited prostate cancer growth both in vitro and in vivo, whereas knockdown of SIRT3 increased prostate tumor growth. Mechanistically, the tumor suppression effect of SIRT3 was achieved via its inhibition of the PI3K/Akt pathway. Notably, upregulation of SIRT3 suppressed the phosphorylation of Akt, leading to the ubiquitination and degradation of oncoprotein c-MYC; this could be attenuated by constitutive activation of PI3K/Akt signaling. Collectively, our results unveiled SIRT3's tumor suppressive function and the underlying mechanism in prostate cancer, which might provide therapeutic implications for the disease.

Purpose: Although a previous study reported nerve endingderived acetylcholine promoted prostate cancer invasion and metastasis by regulating the microenvironment of cancer cells, the present study aims to determine whether there is autocrine cholinergic signaling in prostate epithelial cells that promotes prostate cancer growth and castration resistance.Experimental design: In this study, IHC was performed to detect protein expression in mouse prostate tissue sections and human prostate cancer tissue sections. Subcutaneously and orthotopically xenografted tumor models were established to evaluate the functions of autocrine cholinergic signaling in regulating prostate cancer growth and castration resistance. Western blotting analysis was performed to assess the autocrine cholinergic signaling-induced signaling pathway.Results: We found the expression of choline acetyltransferase (ChAT), the secretion of acetylcholine and the expression of CHRM3 in prostate epithelial cells, supporting the presence of autocrine cholinergic signaling in the prostate epithelium. In addition, we found that CHRM3 was upregulated in clinical prostate cancer tissues compared with adjacent noncancer tissues. Overexpression of CHRM3 or activation of CHRM3 by carbachol promoted cell proliferation, migration, and castration resistance. On the contrary, blockading CHRM3 by shRNA or treatment with darifenacin inhibited prostate cancer growth and castration resistance both in vitro and in vivo. Furthermore, we found that autocrine cholinergic signaling caused calmodulin/calmodulin-dependent protein kinase kinase (CaM/CaMKK)-mediated phosphorylation of Akt.Conclusions: These findings suggest that blockade of CHRM3 may represent a novel adjuvant therapy for castration-resistant prostate cancer.

SummaryAlthough STAT3 signaling is demonstrated to regulate sensory cell differentiation and regeneration in the zebrafish, its exact role is still unclear in mammalian cochleae. Here, we report that STAT3 and its activated form are specifically expressed in hair cells during mouse cochlear development. Importantly, conditional cochlear deletion of Stat3 leads to an inhibition on hair cell differentiation in mice in vivo and in vitro. By cell fate analysis, inactivation of STAT3 signaling shifts the cell division modes from asymmetric to symmetric divisions from supporting cells. Moreover, inhibition of Notch signaling stimulates STAT3 phosphorylation, and inactivation of STAT3 signaling attenuates production of supernumerary hair cells induced by a Notch pathway inhibitor. Our findings highlight an important role of the STAT3 signaling during mouse cochlear hair cell differentiation and may have clinical implications for the recovery of hair cell loss-induced hearing impairment.

Background Adjudin has been explored as a male contraceptive for the last 15 years since its initial synthesis in the late 1990s. More than 50 papers have been published and listed in PubMed in which its mechanism that induces exfoliation of germ cells from the seminiferous epithelium, such as its effects on actin microfilaments at the apical ES (ectoplasmic specialization, a testis-specific actin-rich anchoring junction) has been delineated. Objective Recent studies have demonstrated that, besides its activity to induce germ cell exfoliation from the seminiferous epithelium to cause reversible infertility in male rodents, adjudin possesses other biological activities, which include anti-cancer, anti-inflammation in the brain, and anti-ototoxicity induced by gentamicin in rodents. Results of these findings likely spark the interest of investigators to explore other medical use of this and other indazole-based compounds, possibly mediated by the signaling pathway(s) in the mitochondria of mammalian cells following treatment with adjudin. In this review, we carefully evaluate these recent findings. Methods Papers published and listed at www.pubmed.org and patents pertinent to adjudin and its related compounds were searched. Findings were reviewed and critically evaluated, and summarized herein. Results Adjudin is a novel compound that possesses anti-spermatogenetic activity. Furthermore, it possesses anti-cancer, anti-inflammation, anti-neurodegeneration, and anti-ototoxicity activities based on studies using different in vitro and in vivo models. Conclusion: Studies on adjudin should be expanded to better understand its biological activities so that it can become a useful drug for treatment of other ailments besides serving as a male contraceptive.

Sirtuins are a family of nicotinamide adenine dinucleotide (NAD + ) dependent deacetylases involved in multiple biological functions including metabolism, inflammation, stress resistance and aging. In mammals, there are seven members (Sirt1-Sirt7), with diversities in their subcellular localizations and enzymatic activities. Here, we review the functions of sirtuins, with a focus on their roles in normal brain physiology such as neural development regulation, body homeostasis maintenance, and memory formation. We also discuss the role of sirtuins in a variety of brain diseases including stroke, Alzheimer's, Parkinson's, and motor neuron dysfunction. Because of the emerging functions of sirtuins in brain physiology and pathology, drugs targeting sirtuins may offer potential therapeutic values for brain disorders.