Melatonin involvement in apoptotic processes is a new and relevant field of investigation. Even in tumor models unresponsive to melatonin alone, this hormone can significantly amplify the cytostatic and the cytotoxic effects triggered by other compounds or conventional drugs. We are far from having a satisfactory understanding about how and when melatonin exerts its beneficial effects. Melatonin in the nanomolar range activates the intrinsic and/or the extrinsic apoptotic pathway in cancer cells, namely through an increase in the p53/MDM2p ratio and downregulation of Sirt1. This finding is of great relevance since there is intense research ongoing to identify nontoxic feasible inhibitors of MDM2 and Sirt1. Melatonin should be evaluated for the management of those cancers where both of these are overexpressed and functionally strategic.

Besides being a structural element, myo-inositol exerts unexpected functions, mostly unknown. However, several reports indicate that inositol plays a key role during phenotypic transitions and developmental phases. Furthermore, dysfunctions in the regulation of inositol metabolism have been implicated in several chronic diseases. Clinical trials using inositol in pharmacological doses provide amazing results in the management of gynecological diseases, respiratory stress syndrome, Alzheimer's disease, metabolic syndrome, and cancer, for which conventional treatments are disappointing. However, despite the widespread studies carried out to identify inositol-based effects, no comprehensive understanding of inositol-based mechanisms has been achieved. An integrated metabolomics-genomic study to identify the cellular fate of therapeutically administered myo-inositol and its genomic/enzymatic targets is urgently warranted.

Monitoring hepatitis C virus (HCV) infection among injecting drug users (IDUs) in the community is complicated by difficulties in obtaining biological specimens and biases in recruitment and follow-up. This study examined the utility of dried blood spot (DBS) specimens from IDUs recruited using respondent-driven sampling (RDS). Active IDUs underwent a computer-assisted interview and provided a DBS sample, tested for HCV antibody (anti-HCV) and HCV-RNA. HCV incidence was estimated from the proportion of anti-HCV-negative subjects found HCV-RNA-positive and estimates of the duration of this state. Results were adjusted according to RDS derived sample weights. HCV-RNA testing was performed on 288 DBS samples; 173 were anti-HCV-positive (54% weighted), of which 70 (42%, 95%CI 34-50% weighted) were RNA-negative indicating cleared infection. Among the 115 anti-HCV-negatives, 14 were RNA-positive suggesting an incidence of 38-47 per 100pyrs. Incident infections were younger than anti-HCV-negative and prevalent infections: 25 vs. 29 and 34, respectively. Incidence was highest among individuals with poor needle exchange coverage. One hundred and fourteen were genotyped (60 1a, 46 3a): a cluster of 14 had homology of >98.5% including 10 incident infections. Public health surveillance of HCV among IDUs could be enhanced through the collection of DBS samples with appropriate recruitment approaches. DBS allow differentiation between individuals with cleared infections, ongoing infection and those recently infected. They also enable virus characterization at genotype and nucleotide level. This would allow surveillance to inform development of harm reduction interventions, and the international evidence base for these.

In the past decades, both the importance of inositol for human health and the complex interaction between glucose and inositol have been the subject of increasing consideration. Glucose has been shown to interfere with cellular transmembrane transport of inositol, inhibiting, among others, its intestinal absorption. Moreover, intracellular glucose is required for de novo biosynthesis of inositol through the inositol-3-phosphate synthase 1 pathway, while a few glucose-related metabolites, like sorbitol, reduce intracellular levels of inositol. Furthermore, inositol, via its major isomers myo-inositol and D-chiro-inositol, and probably some of its phosphate intermediate metabolites and correlated enzymes (like inositol hexakisphosphate kinase) participate in both insulin signaling and glucose metabolism by influencing distinct pathways. Indeed, clinical data support the beneficial effects exerted by inositol by reducing glycaemia levels and hyperinsulinemia and buffering negative effects of sustained insulin stimulation upon the adipose tissue and the endocrine system. Due to these multiple effects, myoIns has become a reliable treatment option, as opposed to hormonal stimulation, for insulin-resistant PCOS patients.

No abstract

Microgravity exerts dramatic effects on cell morphology and functions, by disrupting cytoskeleton and adhesion structures, as well as by interfering with biochemical pathways and gene expression. Impairment of cells behavior has both practical and theoretical significance, given that investigations of mechanisms involved in microgravity-mediated effects may shed light on how biophysical constraints cooperate in shaping complex living systems. By exposing breast cancer MDA-MB-231 cells to simulated microgravity (~0.001 g), we observed the emergence of two morphological phenotypes, characterized by distinct membrane fractal values, surface area, and roundness. Moreover, the two phenotypes display different aggregation profiles and adherent behavior on the substrate. These morphological differences are mirrored by the concomitant dramatic functional changes in cell processes (proliferation and apoptosis) and signaling pathways (ERK, AKT, and Survivin). Furthermore, cytoskeleton undergoes a dramatic reorganization, eventually leading to a very different configuration between the two populations. These findings could be considered adaptive and reversible features, given that, by culturing microgravity-exposed cells into a normal gravity field, cells are enabled to recover their original phenotype. Overall these data outline the fundamental role gravity plays in shaping form and function in living systems.

Compelling evidence demonstrated that melatonin increases p53 activity in cancer cells. p53 undergoes acetylation to be stabilized and activated for driving cells destined for apoptosis/growth inhibition. Over-expression of p300 induces p53 acetylation, leading to cell growth arrest by increasing p21 expression. In turn, p53 activation is mainly regulated in the nucleus by MDM2. MDM2 also acts as E3 ubiquitin ligase, promoting the proteasome-dependent p53 degradation. MDM2 entry into the nucleus is finely tuned by two different modulations: the ribosomal protein L11, acts by sequestering MDM2 in the cytosol, whereas the PI3K-AkT-dependent MDM2 phosphorylation is mandatory for MDM2 translocation across the nuclear membrane. In addition, MDM2-dependent targeting of p53 is regulated in a nonlinear fashion by MDM2/MDMX interplay. Melatonin induces both cell growth inhibition and apoptosis in MCF7 breast cancer cells. We previously reported that this effect is associated with reduced MDM2 levels and increased p53 activity. Herein, we demonstrated that melatonin drastically down-regulates MDM2 gene expression and inhibits MDM2 shuttling into the nucleus, given that melatonin increases L11 and inhibits Akt-PI3K-dependent MDM2 phosphorylation. Melatonin induces a 3-fold increase in both MDMX and p300 levels, decreasing simultaneously Sirt1, a specific inhibitor of p300 activity. Consequently, melatonin-treated cells display significantly higher values of both p53 and acetylated p53. Thus, a 15-fold increase in p21 levels was observed in melatonin-treated cancer cells. Our results provide evidence that melatonin enhances p53 acetylation by modulating the MDM2/MDMX/p300 pathway, disclosing new insights for understanding its anticancer effect.

Previous investigations demonstrated that melatonin exerts an oncostatic action on estrogen-responsive breast cancer, both in vitro and in vivo. Nevertheless, the pro-apoptotic effect of melatonin is still a matter of debate. An experimental study was undertaken to focus on melatonin-related apoptosis and to identify the apoptotic pathways involved. Whole cell-count, flow-cytometry analysis and proteins involved in apoptotic pathways [p53, p73, murine double minute 2 (MDM2), caspases-9,-7,-6, cleaved-poly ADP ribose polymerase (PARP), Bcl-2, Bax and apoptotic inducing factor (AIF)] were investigated in human MCF-7 breast cancer cells treated with physiological (1 nM) concentration of melatonin. Melatonin exerts a significant growth-inhibitory effect on MCF-7 cells, becoming evident after 72 hr and thereafter increasing linearly up to 144 hr. In this model, the growth-inhibition is transforming growth factor beta 1 (TGFbeta1)-dependent and it might be reversed by adding an anti-TGFbeta1 antibody. Melatonin induces a significant rise in apoptotic rate, at both 24 and 96 hr. The anti-TGFbeta1 antibody almost completely suppresses melatonin-related late apoptosis; however, early apoptosis is unaffected. Early programmed cell death is associated with a significant increase in the p53/MDM2 ratio and in AIF release, without modifications in caspase activity or cleaved-PARP levels. Activated caspases-9 and -7 and cleaved-PARP increased significantly at 96 hr, concomitantly with a down-regulation of the Bcl-2/Bax ratio. These data suggest that two distinct apoptotic processes are triggered by melatonin in MCF-7 cells: an early, TGFbeta1 and caspase-independent response, and a late apoptotic TGFbeta1-dependent process in which activated-caspase-7 is likely to be the terminal effector.