p70S6 kinase phosphorylation for pharmacodynamic monitoring

Discovery of a Small-Molecule Modulator of the Autophagy-Lysosome Pathway That Targets Lamin A/C and LAMP1, Induces Autophagic Flux, and Affects Lysosome Positioning in Neurons

Autophagy is a major catabolic degradation and recycling process that maintains homeostasis in cells and is especially important in postmitotic neurons. We implemented a high-content phenotypic assay to discover small molecules that promote autophagic flux and completed target identification and validation studies to identify protein targets that modulate the autophagy pathway and promote neuronal health and survival. Efficient syntheses of the prioritized compounds were developed to readily access analogues of the initial hits, enabling initial structure-activity relationship studies to improve potency and preparation of a biotin-tagged pulldown probe that retains activity. This probe facilitated target identification and validation studies through pulldown and competition experiments using both an unbiased proteomics approach and western blotting to reveal Lamin A/C and LAMP1 as the protein targets of compound RH1115. Evaluation of RH1115 in neurons revealed that this compound induces changes to LAMP1 vesicle properties and alters lysosome positioning. Dysfunction of the autophagy-lysosome pathway has been implicated in a variety of neurodegenerative diseases, including Alzheimer's disease, highlighting the value of new strategies for therapeutic modulation and the importance of small-molecule probes to facilitate the study of autophagy regulation in cultured neurons and in vivo.

Immunometabolic Modulatory Role of Naltrexone in BV-2 Microglia Cells

Background: Naltrexone is an opioid receptor antagonist commonly used to treat opioid and alcohol dependence. The use of low dose naltrexone (LDN) was found to have anti-inflammatory properties for treatment of diseases such as fibromyalgia, Crohn’s disease, multiple sclerosis and regional pain syndromes. Related to its anti-neuroinflammatory properties, the mechanism of action is possibly mediated via Toll-like receptor 4 antagonism, which is widely expressed on microglial cells. The aim of the present study was to assess the immunometabolic effects of naltrexone on microglia cells in in vitro conditions. Methods: All experiments were performed in the BV-2 microglial cell line. The cells were treated with naltrexone at 100 μM concentrations corresponding to low dose for 24 h. Cell viability was assessed for every drug dose. To induce additional activation, the cells were pretreated with LPS and IFN-γ. Immunofluorescence was used to analyse the classical microglial activation markers iNOS and CD206, while Seahorse was used for real-time cellular metabolic assessments. mTOR activity measured over the expression of a major direct downstream target S6K was assessed using western blot. Results: LDN induced a shift from highly activated pro-inflammatory phenotype (iNOS^highCD206^low) to quiescent anti-inflammatory M2 phenotype (iNOS^lowCD206^high) in BV-2 microglia cells. Changes in the inflammatory profile were accompanied by cellular metabolic switching based on the transition from high glycolysis to mitochondrial oxidative phosphorylation (OXPHOS). LDN-treated cells were able to maintain a metabolically suppressive phenotype by supporting OXPHOS with high oxygen consumption, and also maintain a lower energetic state due to lower lactate production. The metabolic shift induced by transition from glycolysis to mitochondrial oxidative metabolism was more prominent in cells pretreated with immunometabolic modulators such as LPS and IFN-γ. In a dose-dependent manner, naltrexone also modulated mTOR/S6K expression, which underlies the cell metabolic phenotype regulating microglia immune properties and adaptation. Conclusion: By modulating the phenotypic features by metabolic switching of activated microglia, naltrexone was found to be an effective and powerful tool for immunometabolic reprogramming and could be a promising novel treatment for various neuroinflammatory conditions.

Reactivations of Latent Viral Infections Are Associated with an Increased Thr389 p70S6k Phosphorylation in Peripheral Lymphocytes of Renal Transplant Recipients

Reactivations of BK polyoma virus (BKPyV) and human cytomegalovirus (HCMV) frequently cause life- and graft-threatening complications after renal transplantation. Both viruses are dependent on the mTOR pathway for replication. In this study we investigated the association of viral replication with mTOR activity in peripheral lymphocytes of renal transplant recipients. A flow-cytometry based assay for the measurement of Thr389 p70S6k phosphorylation, a surrogate marker of the mTOR pathway was established. Forty-eight adult renal transplant recipients were recruited to measure p70S6k activity in their peripheral blood mononuclear cells. This data set in conjunction with information concerning previous replication of BKPyV and HCMV was examined for correlations. Episodes of BKPyV replication were significantly associated with increased p70S6k phosphorylation in CD4⁺ T lymphocytes (p = 0.0002) and CD19⁺ B lymphocytes (p = 0.0073). HCMV infection of patients with a high-risk HCMV constellation of donor and recipient (D+/R−) was associated with increased p70S6k phosphorylation in CD19⁺ B lymphocytes (p = 0.0325). These associations were found to be independent of the trough levels of the immunosuppressive drugs. Conclusion: P70S6k phosphorylation in peripheral lymphocytes is associated with BKPyV reactivations and to a lesser extent with HCMV infections in renal transplant recipients.

Ascorbic acid presents rapid behavioral and hippocampal synaptic plasticity effects

Growing evidence has suggested that ascorbic acid may exhibit rapid anxiolytic and antidepressant-like effects. In this study the effects of a single administration of ascorbic acid (1 mg/kg, p.o.), ketamine (1 mg/kg, i.p., a fast-acting antidepressant) and fluoxetine (10 mg/kg, p.o., conventional antidepressant) were investigated on: a) behavioral performance in the novelty suppressed feeding (NSF) test; b) hippocampal synaptic protein immunocontent; c) dendritic spine density and morphology in the dorsal and ventral dentate gyrus (DG) of the hippocampus and d) hippocampal dendritic arborization. Ascorbic acid or ketamine, but not fluoxetine, decreased the latency to feed in the NSF test in mice. This effect was accompanied by increased p70S6K (Thr³⁸⁹) phosphorylation 1 h after ascorbic acid or ketamine treatment, although only ascorbic acid increased synapsin I immunocontent. Ketamine administration increased the dendritic spine density in the dorsal DG, but none of the treatments affected the maturation of dendritic spines in this region. In addition, both ascorbic acid and ketamine increased the dendritic spine density in the ventral DG, particularly the mature spines. Sholl analysis demonstrated no effect of any treatment on hippocampal dendritic arborization. Altogether, the results provide evidence that the behavioral and synaptic responses observed following ascorbic acid administration might occur via the upregulation of synaptic proteins, dendritic spine density, and maturation in the ventral DG, similar to ketamine. These findings contribute to understand the cellular targets implicated in its antidepressant/anxiolytic behavioral responses and support the notion that ascorbic acid may share with ketamine the ability to increase synaptic function.

Targeting Anaplastic Lymphoma Kinase (ALK) in Rhabdomyosarcoma (RMS) with the Second-Generation ALK Inhibitor Ceritinib

Background

The receptor tyrosine kinase (RTK) anaplastic lymphoma kinase (ALK) has been implicated in the tumorigenesis of rhabdomyosarcoma (RMS). However, the exact role of ALK in RMS is debatable and remains to be elucidated.

Objective

To determine the in vitro and in vivo effects and mechanism of action of the second-generation ALK inhibitor ceritinib on RMS cell growth.

Methods

Effects of ceritinib on cell proliferation, wound healing, cell cycle, and RTK signaling were determined in alveolar and embryonal rhabdomyosarcoma (ARMS, ERMS). In addition, possible synergistic effects of combined treatment with ceritinib and the Abl/Src family kinase inhibitor dasatinib were determined.

Results

Ceritinib treatment led to decreased cell proliferation, cell cycle arrest, apoptosis, and decreased in vivo tumor growth for the ARMS subtype. ERMS cell lines were less affected and showed no cell cycle arrest or apoptosis. Both subtypes lacked intrinsic ALK phosphorylation, and ceritinib was shown to affect the IGF1R signaling pathway. High levels of phosphorylated Src (Tyr416) were present following ceritinib treatment, making combined treatment with a Src inhibitor a potential treatment option. Combined treatment of ceritinib and dasatinib showed synergistic effects in both ERMS and ARMS cell lines.

Conclusion

This study shows that monotherapy with an ALK inhibitor, such as ceritinib, in RMS, has no effect on ALK signaling. However, the synergistic effects of ceritinib and dasatinib are promising, most probably due to targeting of IGF1R and Src.

Electronic supplementary material

The online version of this article (10.1007/s11523-017-0528-z) contains supplementary material, which is available to authorized users.

A pharmacodynamic study of sirolimus and metformin in patients with advanced solid tumors

BACKGROUND

Sirolimus is a mammalian target of rapamycin (mTOR) inhibitor. Metformin may potentiate mTOR inhibition by sirolimus while mitigating its adverse effects. We conducted a pilot study to test this hypothesis.

METHODS

Patients with advanced solid tumor were treated with sirolimus for 7 days followed by randomization to either sirolimus with metformin (Arm A) or sirolimus (Arm B) until day 21. From day 22 onwards, all patients received sirolimus and metformin. The primary aim was to compare the change in phospho-p70S6K (pp70S6K) in peripheral blood mononuclear cells (PBMC) from day 8 to day 22 using a two-sample t test. Secondary aims were objective response rate, toxicity, and other serum pharmacodynamic biomarkers (e.g., fasting glucose, triglycerides, insulin, C-peptide, IGF-1, IGF-1R, IGF-BP, and leptin).

RESULTS

24 patients were enrolled, with 18 evaluable for the primary endpoint. There was no significant difference in mean change in pp70S6K in arm A vs. arm B (- 0.12 vs. - 0.16; P = 0.64). Similarly, there were no significant differences in other serum pharmacodynamic biomarkers. There were no partial responses. There were no dose-limiting or unexpected toxicities.

CONCLUSIONS

Adding metformin to sirolimus, although well tolerated, was not associated with significant changes in pp70S6K in PBMC or other serum pharmacodynamic biomarkers.

IMPACT

Combining metformin with sirolimus did not improve mTOR inhibition.

Analytical Aspects of the Implementation of Biomarkers in Clinical Transplantation

In response to the urgent need for new reliable biomarkers to complement the guidance of the immunosuppressive therapy, a huge number of biomarker candidates to be implemented in clinical practice have been introduced to the transplant community. This includes a diverse range of molecules with very different molecular weights, chemical and physical properties, ex vivo stabilities, in vivo kinetic behaviors, and levels of similarity to other molecules, etc. In addition, a large body of different analytical techniques and assay protocols can be used to measure biomarkers. Sometimes, a complex software-based data evaluation is a prerequisite for appropriate interpretation of the results and for their reporting. Although some analytical procedures are of great value for research purposes, they may be too complex for implementation in a clinical setting. Whereas the proof of "fitness for purpose" is appropriate for validation of biomarker assays used in exploratory drug development studies, a higher level of analytical validation must be achieved and eventually advanced analytical performance might be necessary before diagnostic application in transplantation medicine. A high level of consistency of results between laboratories and between methods (if applicable) should be obtained and maintained to make biomarkers effective instruments in support of therapeutic decisions. This overview focuses on preanalytical and analytical aspects to be considered for the implementation of new biomarkers for adjusting immunosuppression in a clinical setting and highlights critical points to be addressed on the way to make them suitable as diagnostic tools. These include but are not limited to appropriate method validation, standardization, education, automation, and commercialization.

Target regulation of PI3K/Akt/mTOR pathway by cannabidiol in treatment of experimental multiple sclerosis

This study was aimed to investigate whether treatment with purified cannabidiol (CBD) may counteract the development of experimental multiple sclerosis (MS), by targeting the PI3K/Akt/mTOR pathway. Although the PI3K/Akt/mTOR pathway was found to be activated by cannabinoids in several immune and non-immune cells, currently, there is no data about the effects of CBD in the PI3K/Akt/mTOR activity in MS. Experimental Autoimmune Encephalomyelitis (EAE), the most common model of MS, was induced in C57BL/6 mice by immunization with myelin oligodendroglial glycoprotein peptide (MOG)_35-55. After EAE onset, which occurs approximately 14days after disease induction, mice were daily intraperitoneally treated with CBD (10mg/kg mouse) and observed for clinical signs of EAE. At 28days from EAE-induction, mice were euthanized and spinal cord tissues were sampled to perform immunohistochemical evaluations and western blot analysis. Our results showed a clear downregulation of the PI3K/Akt/mTOR pathway following EAE induction. CBD treatment was able to restore it, increasing significantly the phosphorylation of PI3K, Akt and mTOR. Also, an increased level of BNDF in CBD-treated mice seems to be involved in the activation of PI3K/Akt/mTOR pathway. In addition, our data demonstrated that therapeutic efficacy of CBD treatment is due to reduction of pro-inflammatory cytokines, like IFN-γ and IL-17 together with an up-regulation of PPARγ. Finally, CBD was found to promote neuronal survival by inhibiting JNK and p38 MAP kinases. These results provide an interesting discovery about the regulation of the PI3K/Akt/mTOR pathway by cannabidiol administration, that could be a new potential therapeutic target for MS management.

Rapamycin and WYE-354 suppress human gallbladder cancer xenografts in mice

Gallbladder cancer (GBC) is a highly malignant tumor characterized by a poor response to chemotherapy and radiotherapy. We evaluated the in vitro and in vivo antitumor efficacy of mTOR inhibitors, rapamycin and WYE-354. In vitro assays showed WYE-354 significantly reduced cell viability, migration and invasion and phospho-P70S6K expression in GBC cells. Mice harboring subcutaneous gallbladder tumors, treated with WYE-354 or rapamycin, exhibited a significant reduction in tumor mass. A short-term treatment with a higher dose of WYE-354 decreased the tumor size by 68.6% and 52.4%, in mice harboring G-415 or TGBC-2TKB tumors, respectively, compared to the control group. By contrast, treatment with a prolonged-low-dose regime of rapamycin almost abrogated tumor growth, exhibiting 92.7% and 97.1% reduction in tumor size, respectively, compared to control mice. These results were accompanied by a greater decrease in the phosphorylation status of P70S6K and a lower cell proliferation Ki67 index, compared to WYE-354 treated mice, suggesting a more effective mTOR pathway inhibition. These findings provide a proof of concept for the use of rapamycin or WYE-354 as potentially good candidates to be studied in clinical trials in GBC patients.

AKT/mTOR substrate P70S6K is frequently phosphorylated in gallbladder cancer tissue and cell lines

Background

Gallbladder carcinoma is a highly malignant tumor and a public health problem in some parts of the world. It is characterized by a poor prognosis and its resistance to radio and chemotherapy. There is an urgent need to develop novel therapeutic alternatives for the treatment of gallbladder carcinoma. The mammalian target of the rapamycin (mTOR) signaling pathway is activated in about 50% of human malignancies, and its role in gallbladder carcinoma has previously been suggested. In the present study, we investigated the phosphorylation status of the mTOR substrate p70S6K in preneoplastic and neoplastic gallbladder tissues and evaluated the effect of three mTOR inhibitors on cell growth and migration in gallbladder carcinoma cell lines.

Methods

Immunohistochemical staining of phospho-p70S6K was analyzed in 181 gallbladder carcinoma cases, classified according to lesion type as dysplasia, early carcinoma, or advanced carcinoma. Protein expression of AKT/mTOR members was also evaluated in eight gallbladder carcinoma cell lines by Western blot analysis. We selected two gallbladder carcinoma cell lines (G415 and TGBC-2TKB) to evaluate the effect of rapamycin, RAD001, and AZD8055 on cell viability, cell migration, and protein expression.

Results

Our results showed that phospho-p70S6K is highly expressed in dysplasia (66.7%, 12/18), early cancer (84.6%, 22/26), and advanced cancer (88.3%, 121/137). No statistical correlation was observed between phospho-p70S6K status and any clinical or pathological features, including age, gender, ethnicity, wall infiltration level, or histological differentiation (P < 0.05). In vitro treatment with rapamycin, RAD001, and AZD8055 reduced cell growth, cell migration, and phospho-p70S6K expression significantly in G-415 and TGBC-2TKB cancer cells (P < 0.001).

Conclusion

Our findings confirm the upregulation of this signaling pathway in gallbladder carcinoma and provide a rationale for the potential use of mTOR inhibitors as a therapeutic strategy for human gallbladder carcinoma.