Modulation of Mcl-1 sensitizes glioblastoma to TRAIL-induced apoptosis.

Glioblastoma (GBM) is the most aggressive form of primary brain tumour, with dismal patient outcome. Treatment failure is associated with intrinsic or acquired apoptosis resistance and the presence of a highly tumourigenic subpopulation of cancer cells called GBM stem cells. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) has emerged as a promising novel therapy for some treatment-resistant tumours but unfortunately GBM can be completely resistant to TRAIL monotherapy. In this study, we identified Mcl-1, an anti-apoptotic Bcl-2 family member, as a critical player involved in determining the sensitivity of GBM to TRAIL-induced apoptosis. Effective targeting of Mcl-1 in TRAIL resistant GBM cells, either by gene silencing technology or by treatment with R-roscovitine, a cyclin-dependent kinase inhibitor that targets Mcl-1, was demonstrated to augment sensitivity to TRAIL, both within GBM cells grown as monolayers and in a 3D tumour model. Finally, we highlight that two separate pathways are activated during the apoptotic death of GBM cells treated with a combination of TRAIL and R-roscovitine, one which leads to caspase-8 and caspase-3 activation and a second pathway, involving a Mcl-1:Noxa axis. In conclusion, our study demonstrates that R-roscovitine in combination with TRAIL presents a promising novel strategy to trigger cell death pathways in glioblastoma.

Latrepirdine is a potent activator of AMP-activated protein kinase and reduces neuronal excitability.

Latrepirdine/Dimebon is a small-molecule compound with attributed neurocognitive-enhancing activities, which has recently been tested in clinical trials for the treatment of Alzheimer's and Huntington's disease. Latrepirdine has been suggested to be a neuroprotective agent that increases mitochondrial function, however the molecular mechanisms underlying these activities have remained elusive. We here demonstrate that latrepirdine, at (sub)nanomolar concentrations (0.1 nM), activates the energy sensor AMP-activated protein kinase (AMPK). Treatment of primary neurons with latrepirdine increased intracellular ATP levels and glucose transporter 3 translocation to the plasma membrane. Latrepirdine also increased mitochondrial uptake of the voltage-sensitive probe TMRM. Gene silencing of AMPKα or its upstream kinases, LKB1 and CaMKKß, inhibited this effect. However, studies using the plasma membrane potential indicator DisBAC2(3) demonstrated that the effects of latrepirdine on TMRM uptake were largely mediated by plasma membrane hyperpolarization, precluding a purely 'mitochondrial' mechanism of action. In line with a stabilizing effect of latrepirdine on plasma membrane potential, pretreatment with latrepirdine reduced spontaneous Ca(2+) oscillations as well as glutamate-induced Ca(2+) increases in primary neurons, and protected neurons against glutamate toxicity. In conclusion, our experiments demonstrate that latrepirdine is a potent activator of AMPK, and suggest that one of the main pharmacological activities of latrepirdine is a reduction in neuronal excitability.

Efficacy and safety of once-daily umeclidinium/vilanterol 62.5/25 mcg in COPD.

STUDY OBJECTIVE: To examine the efficacy and safety of the once-daily, inhaled, long-acting muscarinic antagonist/ß2-agonist combination umeclidinium/vilanterol (UMEC/VI) compared with UMEC and VI monotherapies in patients with chronic obstructive pulmonary disease (COPD). METHODS: In this 24-week, double-blind, placebo-controlled, parallel-group study (ClinicalTrials.gov: NCT01313650) eligible patients were randomised 3:3:3:2 to treatment with UMEC/VI 62.5/25 mcg, UMEC 62.5 mcg, VI 25 mcg or placebo administered once daily via dry powder inhaler (N = 1532; intent-to-treat population). Primary endpoint was trough forced expiratory volume in one second (FEV1) on Day 169 (23-24 h post-dose). Additional lung-function, symptomatic, and health-related quality-of-life endpoints were assessed, including 0-6 h weighted-mean FEV1, rescue salbutamol use, Transition Dyspnoea Index (TDI), Shortness Of Breath With Daily Activity (SOBDA) and St. George's Respiratory Questionnaire (SGRQ) scores. Safety evaluations included adverse events (AEs), vital signs, 12-lead/24-h Holter electrocardiography parameters and clinical laboratory/haematology measurements. RESULTS: All active treatments produced statistically significant improvements in trough FEV1 compared with placebo on Day 169 (0.072-0.167 L, all p < 0.001); increases with UMEC/VI 62.5/25 mcg were significantly greater than monotherapies (0.052-0.095 L, p ≤ 0.004). Improvements were observed for UMEC/VI 62.5/25 mcg vs placebo for weighted-mean FEV1 on Day 168 (0.242 L, p < 0.001), rescue salbutamol use during Weeks 1-24 (-0.8 puffs/day, p = 0.001), TDI (1.2 units, p < 0.001), SOBDA (-0.17 units, p < 0.001) and SGRQ (-5.51 units, p < 0.001) scores. No clinically-significant changes in vital signs, electrocardiography, or laboratory parameters were observed. CONCLUSION: Once-daily UMEC/VI 62.5/25 mcg was well tolerated and provided clinically-significant improvements in lung function and symptoms in patients with COPD.

Activation of executioner caspases is a predictor of progression-free survival in glioblastoma patients: a systems medicine approach.

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. GBM cells are highly resistant to apoptosis induced by antitumor drugs and radiotherapy resulting in cancer progression. We assessed whether a systems medicine approach, analysing the ability of tumor cells to execute apoptosis could be utilized to predict the response of GBM patients to treatment. Concentrations of the key proapoptotic proteins procaspase-3, procaspase-9, Smac and Apaf-1 and the antiapopotic protein XIAP were determined in a panel of GBM cell lines and GBM patient tumor resections. These values were used as input for APOPTO-CELL, a systems biological based mathematical model built to predict cellular susceptibility to undergo caspase activation. The modeling was capable of accurately distinguishing between GBM cells that die or survive in response to treatment with temozolomide in 10 of the 11 lines analysed. Importantly the results obtained using GBM patient samples show that APOPTO-CELL was capable of stratifying patients according to their progression-free survival times and predicted the ability of tumor cells to support caspase activation in 16 of the 21 GBM patients analysed. Calculating the susceptibility to apoptosis execution may be a potent tool in predicting GBM patient therapy responsiveness and may allow for the use of APOPTO-CELL in a clinical setting.

Central roles of apoptotic proteins in mitochondrial function.

Mitochondria have been classically characterized as organelles with responsibility for cellular energy production in the form of ATP, but they are also the organelles through which apoptotic signaling occurs. Cell stress stimuli can result in outer membrane permeabilization, after which mitochondria release numerous proteins involved in apoptotic signaling, including cytochrome c, apoptosis-inducing factor, endonuclease G, Smac/DIABLO and Omi/HtrA2. Cell fate is determined by signaling through apoptotic proteins within the Bcl-2 (B-cell lymphoma 2) protein family, which converges on mitochondria. Many cancerous cells display abnormal levels of Bcl-2 protein family member expression that results in defective apoptotic signaling. Alterations in bioenergetic function also contribute to cancer as well as numerous other disorders. Recent evidence indicates that several pro-apoptotic proteins localized within mitochondria, as well as proteins within the Bcl-2 protein family, can influence mitochondrial bioenergetic function. This review focuses on the emerging roles of these proteins in the control of mitochondrial activity.