Current Medicinal Chemistry - Volume 23, Issue 36, 2016

Background: The control of male fertility requires accurate endocrine, paracrine and autocrine communications along the hypothalamus-pituitary-gonad (HPG) axis. In this respect, the possible interplay between upcoming/classical modulators of reproductive functions deserves attention in that may be a successful tool for the future exploitation of new potential therapeutic targets in the treatment of fertility disorders. Methods: In this review we will discuss upcoming data concerning the role of kisspeptins, the products of the Kiss1 gene, and estrogens - classically considered as female hormones - as well as their possible interplay in testis. Results: Kisspeptins, via the activation of kisspeptin receptor Gpr54 represent the main gatekeeper of the hypothalamic Gonadotropin Releasing Hormone (GnRH) centrally modulating the onset and maintaining reproductive functions. As a consequence, the loss of kisspeptin signalling causes hypogonadotrophic hypogonadism in humans and animal models. In spite of the well recognized functions at hypothalamic levels, recent data strongly support direct production and activity of kisspeptin in testis and its involvement in the control of Leydig cells, germ cells progression and sperm functions. Similarly, estrogens exhibit high impact on proliferative/apoptotic/differentiative events in testis, thus resulting as local key modulators for the production - but also for the release, transport and maturation - of high quality spermatozoa. Conclusion: This review summarizes the upcoming data from experimental models and humans concerning the testicular activity of kisspeptins and estrogens to preserve male fertility. Mutual enhancement of kisspeptin and estradiol signalling for the progression of spermatogenesis has also been discussed.

Transient Receptor Potential Melastatin-related 7 (TRPM7) is a non-selective cation channel fused with a functional kinase domain. Physiologically, TRPM7 channel is involved in magnesium homeostasis, cell survival and gastrulation. The channel part is responsible for calcium, magnesium, and metal trace entries. Cation current through TRPM7 channel is inhibited by both intracellular magnesium and magnesium complexed with nucleotides. In parallel, the kinase is able to phosphorylate cytoskeleton proteins like myosin chain regulating cell tension and motility. Moreover, TRPM7 kinase domain can be cleaved by caspase and participates to apoptosis signaling. Importantly, TRPM7 channel expression is aberrant in numerous cancers including breast, glioblastoma, nasopharynx, ovarian, and pancreatic. Moreover, TRPM7 high expression is an independent biomarker of poor outcome in breast cancer. Pharmacological modulation or silencing of TRPM7 strongly affects proliferation, adhesion, migration or invasion in cancer cell lines. Nevertheless, it is still not clear by which mechanism TRPM7 channels may disturb cancer cell hallmarks. In the present review, we will discuss the role of TRPM7 channels in malignancies. In particular, we will distinguish the role of cation signaling from kinase function in order to better understand how TRPM7 channels may play a central role in cancer progression. We will also discuss the recent advances in pharmacological blockers of TRPM7 and their potential use for cancer therapy.

DNA-binding compounds are of extraordinary importance in medicine, accounting for a substantial portion of antitumor drugs in clinical usage. However, their mechanisms of action remain sometimes incompletely understood. This review critically examines two broad classes of molecules that bind noncovalently to DNA: intercalators and groove binders. Intercalators bind to DNA by inserting their chromophore moiety between two consecutive base pairs, whereas groove binders fit into the grooves of DNA. Noncovalent DNAinteractive drugs can recognize certain supramolecular DNA structures such as the Gquadruplexes found in telomeres and in numerous gene promoters, and they can act as topoisomerase I and II poisons. We discuss how DNA-binding compounds affect transcription and compete with protein factors for binding to consensus binding sites in gene promoters both in vitro and in cultured cancer cells. Moreover, we comment on the design of molecules that can tightly and specifically bind to any desired target DNA, such as various hairpin polyamides which efficacy as chemotherapeutic agents is being evaluated. At present, genome-wide studies, which provide details of events that may influence both cancer progression and therapeutic outcome, are a common way used to analyze the effects of DNA-binding compounds. A conclusive feature that emerges from reviewing the information on DNA-binding compounds is that both natural sources and chemical approaches can be productively used to obtain drugs to manipulate gene expression in cancer cells.

Gastric cancer is among the leading causes of cancer related death worldwide. Patients with gastric cancer are typically asymptomatic, and diagnosed at late stages, supporting the need for the identification of novel prognostic and diagnostic biomarkers. Recently, microRNAs have emerged as molecular regulators that can play key roles in pathogenesis and progression of different malignancies, including gastric cancer. There is a growing body of evidence showing the aberrant activation of some known circulating miRNAs, e.g. let-7a, miR-21, miR-16, miR-93, miR- 103, miR-192a s well as tissue specific-miRNAs, e.g. miR-18a, miR-10b, miR-544, miR-195, miR-378, miR-34a, miR-145 in patients affected by gastric cancer, which involved with modulation of gastric-cancer-associated genes. In addition, there are mounting evidences on the value of miRNAs which are detected to be associated with drug-resistance mechanisms; suggesting their modulation as a potential approach to overcome chemo-resistance. Attuned with these facts, in this review we highlight several recent preclinical and clinical studies performed on circulating and tissue-specific miRNAs as promising biomarkers for detection of patients at early stages, prediction of prognosis, and monitoring of the patients in response to therapy.

The central nervous system (CNS) is a mythical target for drug delivery. There is an ongoing debate over the brain accessibility of flavonoids, a group of plant-derived secondary metabolites widely known by their multifarious bioactivities achieved by distinct mechanisms. Recently, their applicability in the management of neurologic and psychiatric disorders, such as Alzheimer’s and Parkinson’s diseases, and major depression, has received particular attention. To reach their target, flavonoids must cross over the ultimate obstacle - the blood-brain barrier - at pharmacologically effective concentrations. This review addresses the low brain-bioavailability issue, based on in vitro and in vivo evidences. Besides the lipophilic character of the flavonoids, their permeability will depend upon the role of membrane transporters, especially those from the ABC superfamily. The enzymatic elements, namely β-glucuro-nidase, can induce a transient deconjugation process and affect permeability, as well. Novel drug delivery systems are successful strategies to overcome the low bioavailability issue, and redirect the native forms to CNS-targets. This work bridges a solid opinion over this hot topic of medicinal chemistry and natural products research.