Statin-associated muscular and renal adverse events: data mining of the public version of the FDA adverse event reporting system

Objective

Adverse event reports (AERs) submitted to the US Food and Drug Administration (FDA) were reviewed to assess the muscular and renal adverse events induced by the administration of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) and to attempt to determine the rank-order of the association.

Methods

After a revision of arbitrary drug names and the deletion of duplicated submissions, AERs involving pravastatin, simvastatin, atorvastatin, or rosuvastatin were analyzed. Authorized pharmacovigilance tools were used for quantitative detection of signals, i.e., drug-associated adverse events, including the proportional reporting ratio, the reporting odds ratio, the information component given by a Bayesian confidence propagation neural network, and the empirical Bayes geometric mean. Myalgia, rhabdomyolysis and an increase in creatine phosphokinase level were focused on as the muscular adverse events, and acute renal failure, non-acute renal failure, and an increase in blood creatinine level as the renal adverse events.

Results

Based on 1,644,220 AERs from 2004 to 2009, signals were detected for 4 statins with respect to myalgia, rhabdomyolysis, and an increase in creatine phosphokinase level, but these signals were stronger for rosuvastatin than pravastatin and atorvastatin. Signals were also detected for acute renal failure, though in the case of atorvastatin, the association was marginal, and furthermore, a signal was not detected for non-acute renal failure or for an increase in blood creatinine level.

Conclusions

Data mining of the FDA''s adverse event reporting system, AERS, is useful for examining statin-associated muscular and renal adverse events. The data strongly suggest the necessity of well-organized clinical studies with respect to statin-associated adverse events.     

Cyclosporin A associated helicase-like protein facilitates the association of hepatitis C virus RNA polymerase with its cellular cyclophilin B

Background

Cyclosporin A (CsA) is well known as an immunosuppressive drug useful for allogeneic transplantation. It has been reported that CsA inhibits hepatitis C virus (HCV) genome replication, which indicates that cellular targets of CsA regulate the viral replication. However, the regulation mechanisms of HCV replication governed by CsA target proteins have not been fully understood.

Principal Findings

Here we show a chemical biology approach that elucidates a novel mechanism of HCV replication. We developed a phage display screening to investigate compound-peptide interaction and identified a novel cellular target molecule of CsA. This protein, named CsA associated helicase-like protein (CAHL), possessed RNA-dependent ATPase activity that was negated by treatment with CsA. The downregulation of CAHL in the cells resulted in a decrease of HCV genome replication. CAHL formed a complex with HCV-derived RNA polymerase NS5B and host-derived cyclophilin B (CyPB), known as a cellular cofactor for HCV replication, to regulate NS5B-CyPB interaction.

Conclusions

We found a cellular factor, CAHL, as CsA associated helicase-like protein, which would form trimer complex with CyPB and NS5B of HCV. The strategy using a chemical compound and identifying its target molecule by our phage display analysis is useful to reveal a novel mechanism underlying cellular and viral physiology.     

Novel escape mutants suggest an extensive TRIM5α binding site spanning the entire outer surface of the murine leukemia virus capsid protein

After entry into target cells, retroviruses encounter the host restriction factors such as Fv1 and TRIM5α. While it is clear that these factors target retrovirus capsid proteins (CA), recognition remains poorly defined in the absence of structural information. To better understand the binding interaction between TRIM5α and CA, we selected a panel of novel N-tropic murine leukaemia virus (N-MLV) escape mutants by a serial passage of replication competent N-MLV in rhesus macaque TRIM5α (rhTRIM5α)-positive cells using a small percentage of unrestricted cells to allow multiple rounds of virus replication. The newly identified mutations, many of which involve changes in charge, are distributed over the outer 'top' surface of N-MLV CA, including the N-terminal β-hairpin, and map up to 29 A(o) apart. Biological characterisation with a number of restriction factors revealed that only one of the new mutations affects restriction by human TRIM5α, indicating significant differences in the binding interaction between N-MLV and the two TRIM5αs, whereas three of the mutations result in dual sensitivity to Fv1(n) and Fv1(b). Structural studies of two mutants show that no major changes in the overall CA conformation are associated with escape from restriction. We conclude that interactions involving much, if not all, of the surface of CA are vital for TRIM5α binding.     

Cell Cycle Regulation of Microtubule Interactomes: Multi-layered Regulation Is Critical for the Interphase/Mitosis Transition

Microtubules dramatically change their dynamics and organization at the entry into mitosis. Although this change is mediated by microtubule-associated proteins (MAPs), how MAPs themselves are regulated is not well understood. Here we used an integrated multi-level approach to establish the framework and biological significance of MAP regulation critical for the interphase/mitosis transition. Firstly, we applied quantitative proteomics to determine global cell cycle changes in the profiles of MAPs in human and Drosophila cells. This uncovered a wide range of cell cycle regulations of MAPs previously unidentified. Secondly, systematic studies of human kinesins highlighted an overlooked aspect of kinesins: most mitotic kinesins suppress their affinity to microtubules or reduce their protein levels in interphase in combination with nuclear localization. Thirdly, in-depth analysis of a novel Drosophila MAP (Mink) revealed that the suppression of the microtubule affinity of this mitotic MAP in combination with nuclear localization is essential for microtubule organization in interphase, and phosphorylation of Mink is needed for kinetochore-microtubule attachment in mitosis. Thus, this first comprehensive analysis of MAP regulation for the interphase/mitosis transition advances our understanding of kinesin biology and reveals the prevalence and importance of multi-layered MAP regulation.Microtubules are universally found in eukaryotic cells and are involved in diverse processes including cell division, polarity, and intracellular transport. A striking feature of microtubules is that they change their dynamics and organization depending on cellular contexts. Proteins that interact with microtubules, collectively called microtubule-associated proteins (MAPs),¹ are considered to play a major role in determining microtubule dynamics and organization.Although MAPs in general lack recognizable sequence motifs, many MAPs from various sources have been successfully identified by means of biochemical purification followed by mass spectrometry (1–4). However, functional analysis is more problematic, as hundreds of MAPs can interact with microtubules. In addition, multiple MAPs have functional redundancy (5–7), making their biological function often difficult to determine, which results in their importance being grossly underappreciated. Furthermore, it is challenging to understand how MAPs collectively determine the diverse organization and dynamics of microtubules in different cells.One of the most dramatic changes of microtubule organization is found at the transition from interphase to mitosis. During mitosis, microtubules are much more dynamic and are organized into a dense bipolar structure, the spindle, whereas microtubules in interphase are less dynamic and are arranged in a radial array. This transition is rapid and is thought to reflect mainly a change in the activities of both motor and nonmotor MAPs (8); however, we do not have sufficient knowledge of how MAPs themselves are regulated. It is crucial to identify and understand the regulation of MAPs whose activities change in the cell cycle, and how they collectively change microtubule dynamics and organization. Misregulation of such MAPs could interfere with chromosome segregation or cell polarity and potentially contribute to oncogenesis (9). Also, this misregulation can be used to elucidate important functions that are masked due to functional redundancy.We hypothesize that some proteins bind to microtubules only during mitosis and are released from microtubules in interphase. The binding of such proteins to spindle microtubules in mitosis could collectively trigger the formation of the functional spindle, and, of equal importance, removing such proteins from microtubules at the mitotic exit could be essential for disassembling the spindle and proper organization and/or function of interphase microtubules. Conversely, some proteins may bind to microtubules specifically during interphase. No studies have been reported that systematically identify proteins whose microtubule-binding activities change between interphase and mitosis.Here we report a combined approach integrating three levels of analyses to gain insights into how MAPs are regulated as a whole to drive microtubule reorganization at the transition between interphase and mitosis. Firstly, we applied proteomics to determine the quantitative change of the global MAP profile between mitosis and interphase in both human and Drosophila cells. Secondly, we systematically analyzed the human kinesin superfamily for cell cycle localization in relation to microtubule association to gain insight into the general principle of MAP regulation in the cell cycle. Thirdly, we focused on one novel Drosophila MAP to understand the molecular mechanism and biological significance of MAP regulation. This integrated approach has provided the framework of MAP regulation critical for the interphase/mitosis transition.     

Effects of dehydration on immune functions after a judo practice session

We investigated the effects of dehydration after a judo practice session on player muscle and immune functions. Subjects included 25 female university judoists. Investigations were performed before and after 2.5 h of regular judo practice. Body composition, serum enzymes (myogenic enzymes, immunoglobulins and complements), neutrophils counts, reactive oxygen species (ROS) production capability, and phagocytic activity (PA) were measured. Subjects were divided into two groups according to level of dehydration after practice (mild dehydration and severe dehydration groups) and results were compared. Creatine kinase was found to increase significantly after practice. In addition, neutrophil count also increased significantly after practice in both groups. The changing ratios of IgA, IgG and C3 observed in the mild dehydration group were significantly higher than those in the severe dehydration group. In the severe dehydration group, post‐practice PA/neutrophil had decreased significantly. Significant positive correlations were found between severity of dehydration and changing ratios of IgA, IgG, IgM, C3, C4 and ROS production capabilities, whereas no significant association was seen with PA and/or serum SOD activity. These results suggest that dehydration resulted in immunosuppression, including decreased neutrophil function. Copyright © 2012 John Wiley & Sons, Ltd.     

Intermittent exposure to traces of green leaf volatiles triggers the production of (Z)-3-hexen-1-yl acetate and (Z)-3-hexen-1-ol in exposed plants

Intermittent exposure during a period of 3 weeks of undamaged Arabidopsis plants to trace amounts of volatiles emitted by freshly damaged Arabidopsis plants resulted in an increase of subsequent artificial-damage-induced production of (Z)-3-hexen-1-yl acetate and (Z)-3-hexen-1-ol in the exposed Arabidopsis plants when compared with Arabidopsis plants exposed to undamaged Arabidopsis plant volatiles (control plants). We previously showed that (Z)-3-hexen-1-yl acetate attracts a parasitic wasp, Cotesia glomerata. Thus, the induced production of this volatile explained our previously reported finding that, when artificially damaged, the exposed plants were more attractive to C. glomerata than control plants.     

Impact of Diabetes on Oncologic Outcome of Colorectal Cancer Patients: Colon vs. Rectal Cancer

Background

To evaluate the impact of diabetes on outcomes in colorectal cancer patients and to examine whether this association varies by the location of tumor (colon vs. rectum).

Patients and methods

This study includes 4,131 stage I-III colorectal cancer patients, treated between 1995 and 2007 (12.5% diabetic, 53% colon, 47% rectal) in South Korea. Cox proportional hazards modeling was used to determine the prognostic influence of DM on survival endpoints.

Results

Colorectal cancer patients with DM had significantly worse disease-free survival (DFS) [hazard ratio (HR) 1.17, 95% confidence interval (CI): 1.00–1.37] compared with patients without DM. When considering colon and rectal cancer independently, DM was significantly associated with worse overall survival (OS) (HR: 1.46, 95% CI: 1.11–1.92), DFS (HR: 1.45, 95% CI: 1.15–1.84) and recurrence-free survival (RFS) (HR: 1.32, 95% CI: 0.98–1.76) in colon cancer patients. No association for OS, DFS or RFS was observed in rectal cancer patients. There was significant interaction of location of tumor (colon vs. rectal cancer) with DM on OS (P = 0.009) and DFS (P = 0.007).

Conclusions

This study suggests that DM negatively impacts survival outcomes of patients with colon cancer but not rectal cancer.     

Non-Specific Protein Modifications by a Phytochemical Induce Heat Shock Response for Self-Defense

Accumulated evidence shows that some phytochemicals provide beneficial effects for human health. Recently, a number of mechanistic studies have revealed that direct interactions between phytochemicals and functional proteins play significant roles in exhibiting their bioactivities. However, their binding selectivities to biological molecules are considered to be lower due to their small and simple structures. In this study, we found that zerumbone, a bioactive sesquiterpene, binds to numerous proteins with little selectivity. Similar to heat-denatured proteins, zerumbone-modified proteins were recognized by heat shock protein 90, a constitutive molecular chaperone, leading to heat shock factor 1-dependent heat shock protein induction in hepa1c1c7 mouse hepatoma cells. Furthermore, oral administration of this phytochemical up-regulated heat shock protein expressions in the livers of Sprague-Dawley rats. Interestingly, pretreatment with zerumbone conferred a thermoresistant phenotype to hepa1c1c7 cells as well as to the nematode Caenorhabditis elegans. It is also important to note that several phytochemicals with higher hydrophobicity or electrophilicity, including phenethyl isothiocyanate and curcumin, markedly induced heat shock proteins, whereas most of the tested nutrients did not. These results suggest that non-specific protein modifications by xenobiotic phytochemicals cause mild proteostress, thereby inducing heat shock response and leading to potentiation of protein quality control systems. We considered these bioactivities to be xenohormesis, an adaptation mechanism against xenobiotic chemical stresses. Heat shock response by phytochemicals may be a fundamental mechanism underlying their various bioactivities.     

Metformin,a Diabetes Drug,Eliminates Tumor-Initiating Hepatocellular Carcinoma Cells

Metformin has been widely used as an oral drug for diabetes mellitus for approximately 60 years. Interestingly, recent reports showed that metformin exhibited an anti-tumor action in a wide range of malignancies including hepatocellular carcinoma (HCC). In the present study, we investigated its impact on tumor-initiating HCC cells. Metformin suppressed cell growth and induced apoptosis in a dose-dependent manner. Flow cytometric analysis showed that metformin treatment markedly reduced the number of tumor-initiating epithelial cell adhesion molecule (EpCAM)⁺ HCC cells. Non-adherent sphere formation assays of EpCAM⁺ cells showed that metformin impaired not only their sphere-forming ability, but also their self-renewal capability. Consistent with this, immunostaining of spheres revealed that metformin significantly decreased the number of component cells positive for hepatic stem cell markers such as EpCAM and α-fetoprotein. In a xenograft transplantation model using non-obese diabetic/severe combined immunodeficient mice, metformin and/or sorafenib treatment suppressed the growth of tumors derived from transplanted HCC cells. Notably, the administration of metformin but not sorafenib decreased the number of EpCAM⁺ cells and impaired their self-renewal capability. As reported, metformin activated AMP-activated protein kinase (AMPK) through phosphorylation; however its inhibitory effect on the mammalian target of rapamycin (mTOR) pathway did not necessarily correlate with its anti-tumor activity toward EpCAM⁺ tumor-initiating HCC cells. These results indicate that metformin is a promising therapeutic agent for the elimination of tumor-initiating HCC cells and suggest as-yet-unknown functions other than its inhibitory effect on the AMPK/mTOR pathway.