Alpha ketoglutarate exerts a pro-osteogenic effect in osteoblast cell lines through activation of JNK and mTOR/S6K1/S6 signaling pathways

Although numerous in vivo studies have suggested that alpha-ketoglutarate (AKG), i.e. the key intermediate in the Krebs cycle, may have an anabolic effect on bone tissue, the direct influence of AKG on osteoblasts and the underlying mechanism of its action have not been investigated so far. The aim of this study was to assess the impact of AKG (disodium salt dihydrate) on osteogenesis in vitro and identification of some signaling mechanisms involved in this activity. The human and mouse normal osteoblast cell lines hFOB 1.19 and MC3T3-E1 were used in this study. The results showed that AKG did not increase the proliferation of osteoblasts; however, it upregulated the expression of transcription factors RUNX2 and Osterix, the mRNA and protein levels of osteoblast differentiation markers (alkaline phosphatase, type I collagen, bone sialoprotein II, osteopontin, osteocalcin), and the mineralization levels in the hFOB 1.19 and MC3T3-E1 cell cultures. Moreover, AKG increased JNK, mTOR, S6K1, and S6 phosphorylation and decreased ERK1/2 phosphorylation in both osteoblast cell lines. The JNK inhibitor and rapamycin, but not the ERK inhibitor, abolished the AKG-promoted osteoblast differentiation. Using immunofluorescence staining, qRT-PCR, and Western blot analysis, we detected the presence of an AKG receptor GPR99 activated by alpha ketoglutaric acid in the tested osteoblast cell lines. However, AKG salt did not activate GPR99. Our findings suggest that AKG salt activates the JNK and mTOR/S6K1/S6 signaling pathways to promote differentiation of osteoblasts, independently of GPR99 activation. We can conclude that AKG salts might be promising candidates for bone anabolic drugs used for prevention or/and treatment of osteoporosis.

The impact of sirolimus therapy on lesion size, clinical symptoms, and quality of life of patients with lymphatic anomalies

BACKGROUND

Lymphatic anomalies (LAs) include several disorders in which abnormal lymphatic tissue invades the neck, chest, and various organs. Progressive cases may result in lethal outcomes and have proven difficult to treat. Sirolimus is showing promising results in the management of vascular anomalies. We examined the efficacy and safety of sirolimus treatment in patients with progressive LAs.

METHODS

All patients with LAs treated with sirolimus from May 2015 to September 2018 were included. They received oral sirolimus once a day and the dose was adjusted so that the trough concentration remained within 5-15 ng/mL. We prospectively reviewed the response to drugs (the response rate of radiological volumetric change of the target lesion), severity scores, reported quality of life (QOL), and adverse effects at 6 months after administration.

RESULTS

Twenty patients (five with cystic lymphatic malformation (LM), three with kaposiform lymphangiomatosis, three with generalized lymphatic anomaly, six with Gorham-Stout disease, and three with central conducting lymphatic anomaly) were treated with sirolimus at our institution. Fifty percent of patients (10/20) demonstrated a partial response by a radiological examination and a significant improvement in disease severity and QOL scores (P = 0.0020 and P = 0.0117, respectively). Ten patients who had no reduction in lesion size (stable disease group) showed no significant improvement in disease severity and QOL scores. Eighty percent of patients (16/20) had side effects, such as stomatitis, infection, and hyperlipidemia.

CONCLUSIONS

Sirolimus impacts the reduction of the lymphatic tissue volume of LMs and could lead to improvement in clinical symptoms and QOL.

TRIAL REGISTRATION

UMIN Clinical Trials Registry, UMIN000016580 . Registered 19 February 2015.

Neuronally derived extracellular vesicles: an emerging tool for understanding Alzheimer's disease

In order for Alzheimer’s disease (AD) to manifest, cells must communicate “pathogenic material” such as proteins, signaling molecules, or genetic material to ensue disease propagation. Small extracellular vesicles are produced via the endocytic pathways and released by nearly all cell types, including neurons. Due to their intrinsic interrelationship with endocytic processes and autophagy, there has been increased interest in studying the role of these neuronally-derived extracellular vesicles (NDEVs) in the propagation of AD. Pathologic cargo associated with AD have been found in a number of studies, and NDEVs have been shown to induce pathogenesis in vivo and in vitro. Exogenous NDEVs are also shown to reduce plaque burden in AD models. Thus, the NDEV has the potential to become a useful biomarker, a pathologic potentiator, and a therapeutic opportunity. While the field of NDEV research in AD is still in its infancy, we review the current literature supporting these three claims.

Panax notoginseng saponins promote liver regeneration through activation of the PI3K/AKT/mTOR cell proliferation pathway and upregulation of the AKT/Bad cell survival pathway in mice

Backgroud

The regenerative capacity of the liver is crucial for the host to survive after serious hepatic injuries, tumor resection, or living donor liver transplantation. Panax notoginseng saponins (PNS) have been reported to exert protective effects during organ injuries. The present study aimed to evaluate the effect of PNS on liver regeneration(LR) and on injuries induced by partial hepatectomy (PH).

Methods

We performed 70% partial PH on C57BL/6 J mice treated with or without PNS. LR was estimated by liver weight/body weight, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and cell proliferation, and the related cellular signals were analyzed by Western blot.

Results

Different concentrations of PNS promoted hepatocyte proliferation in vitro. Mice in the PNS group showed higher liver/body weight ratios at 2 d and 7 d (P < 0.05) after PH and lower levels of serum ALT and AST (P < 0.05) compared to those of mice in the normal control (NC) group. Histological analysis showed that the expression of proliferating cell nuclear antigen(PCNA) at 2 d and 7 d after PH was significantly higher in the PNS group than in the NC group (P < 0.05). Mechanistically, the AKT/mTOR cell proliferation pathway and AKT/Bad cell survival pathway were activated by PNS, which accelerated hepatocyte proliferation and inhibited apoptosis (P < 0.05).

Conclusions

PNS promoted liver regeneration through activation of PI3K/AKT/mTOR and upregulated the AKT/Bad cell pathways in mice.

Crocin induces anti-ischemia in middle cerebral artery occlusion rats and inhibits autophagy by regulating the mammalian target of rapamycin

Crocin, an active compound found in Gardenia jasminoides Ellis, has been shown to possess neuron-protective properties, but its potential mechanisms of action still remain poorly understood. In this study, the anti-ischemic effect and underlying mechanism of action of crocin were investigated in male rats with right middle cerebral artery occlusion/reperfusion. Computed tomography and magnetic resonance imaging were used to evaluate the area of infarction 24 h after reperfusion. Neurological scores were employed to evaluate nerve injury. Direct 2,3,5-triphenyltetrazolium chloride staining was used to calculate the infarct ratio 120 h after reperfusion. Finally, HT22 cells and Western blot were used to study the underlying mechanisms. Crocin showed a decreased infarct volume and neurological score in vivo, while the expression of LC3-II/I and AMP-activated protein kinase was remarkably down-regulated with increased levels of p62 and mammalian target of rapamycin (mTOR) expression. However, rapamycin significantly inhibited mTOR, which can impact the anti-ischemic effect of crocin in vitro. These results suggest that crocin may elicit an anti-ischemic effect probably through the mTOR pathway.

Persistently Upregulated Hippocampal mTOR Signals Mediated by Fecal SCFAs Impair Memory in Male Pups with SMM Exposure in Utero

OBJECTIVE

To investigate the molecular mechanisms of the adverse effects of exposure to sulfamonomethoxin (SMM) in pregnancy on the neurobehavioral development of male offspring.

METHODS

Pregnant mice were randomly divided into four groups: control- (normal saline), low- [10 mg/(kg•day)], middle- [50 mg/(kg•day)], and high-dose [200 mg/(kg•day)] groups, which received SMM by gavage daily during gestational days 1-18. We measured the levels of short-chain fatty acids (SCFAs) in feces from dams and male pups. Furthermore, we analyzed the mRNA and protein levels of genes involved in the mammalian target of rapamycin (mTOR) pathway in the hippocampus of male pups by RT-PCR or Western blotting.

RESULTS

Fecal SCFA concentrations were significantly decreased in dams. Moreover, the production of individual fecal SCFAs was unbalanced, with a tendency for an increased level of total fecal SCFAs in male pups on postnatal day (PND) 22 and 56. Furthermore, the phosphatidylinositol 3-kinase (PI3k)/protein kinase B (AKT)/mTOR or mTOR/ribosomal protein S6 kinase 1 (S6K1)/4EBP1 signaling pathway was continuously upregulated until PND 56 in male offspring. In addition, the expression of Sepiapterin Reductase (SPR), a potential target of mTOR, was inhibited.

CONCLUSION

In utero exposure to SMM, persistent upregulation of the hippocampal mTOR pathway related to dysfunction of the gut (SCFA)-brain axis may contribute to cognitive deficits in male offspring.

Protective role of Apelin-13 on amyloid β25-35-induced memory deficit; Involvement of autophagy and apoptosis process

Alzheimer's disease (AD) by progressive neurodegenerative pattern is associated with autophagy stress which is suggested as a potential cause of amyloid β (Aβ) aggregation and neural loss. Apelin-13, a neuropeptide with modulatory effect on autophagy, has been shown the beneficial effects on neural cell injuries. We investigated the effect of Apelin-13 on Aβ-induced memory deficit as well as autophagy and apoptosis processes. We performed bilateral intra-CA1 injection of Aβ25-35 alone or in combination with Apelin-13. Spatial reference and working memory was evaluated using the Morris water maze (MWM) and Y-maze tests. Hippocampus was harvested on 2, 5, 10 and 21 days after Aβ injection. The light chain 3 (LC3II/I) ratio, histone deacetylase 6 (HDAC6) level, Caspase-3 cleavage, and mTOR phosphorylation were assessed using western blot technique. Intra-CA1 injection of Aβ caused impairment of working and spatial memory. We observed higher LC3II/I ratio, cleaved caspase-3 and lower HDAC6, and p-mTOR/mTOR ratio in Aβ-treated animals. Apelin-13 provided significant protection against the destructive effects of Aβ on working and spatial memory. Apelin-13 prevented the increase of LC3II/I ratio and cleaved caspase-3 on days 10 and 21 after injection of Aβ. It also limited the Aβ-induced reduction in HDAC6 expression. This implies that Apelin-13 has suppressed both autophagy and apoptosis. Our findings suggested that the neuroprotection of Apelin-13 may be in part related to autophagy and apoptosis inhibition via the mTOR signaling pathway. Apelin-13 may be a promising approach to improve memory impairment and potentially pave the way for new therapeutic plans in AD.

Hepatoprotective activity of metformin: A new mission for an old drug?

Metformin, as a dimethyl biguanide prescribed as the first-line medication for treatment of type 2 diabetes mellitus, is one of the most frequently used drugs, worldwide. However, the beneficial effects of metformin are not limited to insulin sensitizing and blood glucose lowering effects as recent clinical trials deciphered lower cancer risk in metformin users. In addition, metformin protected the liver against chemical or viral hepatotoxicants through various mechanisms including activation of AMPK via inhibition of mitochondrial complex I, inhibition of mitogen activated protein kinase (MAPK) and inhibition of Smads phosphorylation. Clinical trials are under way to assess possible additive effects of metformin when co-administered along with the standard regimen for hepatocellular carcinoma (HCC) treatment. This review outlines the molecular mechanisms behind protective activity of metformin against different liver diseases.

Everolimus plus Exemestane for Hormone Receptor-Positive Advanced Breast Cancer: A PAM50 Intrinsic Subtype Analysis of BOLERO-2

BACKGROUND

The prognostic and predictive value of the two nonluminal (human epidermal growth factor receptor 2 [HER2]-enriched and basal-like) subtypes within advanced hormone receptor-positive (HR+) breast cancer is currently unknown.

MATERIALS AND METHODS

This study retrospectively analyzed 261 tumors (80.7% primary; 19.3% metastatic) from the BOLERO-2 study; BOLERO-2 randomized 724 patients with advanced HR+/HER2-negative breast cancer to everolimus plus exemestane or placebo plus exemestane. Tumors were classified using a PAM50 subtype predictor. Multivariable Cox regression analyses tested the independent prognostic significance of PAM50, and associations between PAM50 subtypes and treatment upon progression-free survival (PFS) were evaluated.

RESULTS

Subtype distribution was 46.7% luminal A (n = 122), 21.5% HER2-enriched (n = 56), 15.7% luminal B (n = 41), 14.2% normal-like (n = 37), and 1.9% basal-like (n = 5); HER2-enriched subtypes were more common in metastatic versus primary tumors (32.0% vs. 18.7%; p = .038). Median PFS differences between luminal and nonluminal (6.7 vs. 5.2 months; adjusted hazard ratio, 0.66; 95% confidence interval [CI], 0.47-0.94; p = .020) and HER2-enriched and non-HER2-enriched subtypes (5.2 vs. 6.2 months; adjusted hazard ratio, 1.53; 95% CI, 1.07-2.19; p = .019) were significant. Everolimus plus exemestane significantly improved median PFS versus placebo plus exemestane among patients with HER2-enriched tumors (5.8 vs. 4.1 months; adjusted hazard ratio, 0.49; 95% CI, 0.26-0.90; p = .034); however, the association between HER2-enriched tumors and everolimus benefit was nonsignificant (p = .433).

CONCLUSION

The HER2-enriched subtype was identified in a substantial proportion of advanced HR+/HER2-negative breast tumors, and was a consistent biomarker of poor prognosis. Tailored therapies are therefore needed for HER2-enriched tumors in the advanced HR+/HER2-negative breast cancer setting.

IMPLICATIONS FOR PRACTICE

Using 261 tumor samples from the BOLERO-2 phase III clinical trial, this study shows that a substantial proportion (20%-30%) of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancers do not have a luminal A or B gene expression profile. This group of patients with nonluminal disease has a poor survival outcome regardless of the addition of everolimus to exemestane. This is the second study that confirms the prognostic value of this biomarker. Overall, these findings indicate a necessity to design novel clinical trials targeting nonluminal disease within HR+/HER2-negative breast cancer.

Efficacy and safety of sirolimus treatment for intractable lymphatic anomalies: A study protocol for an open-label, single-arm, multicenter, prospective study (SILA)

Introduction

Lymphatic anomalies (LAs) refer to a group of diseases involving systemic dysplasia of lymphatic vessels. These lesions are classified as cystic lymphatic malformation (macrocystic, microcystic or mixed), generalized lymphatic anomaly, and Gorham–Stout disease. LAs occur mainly in childhood, and present with various symptoms including chronic airway problems, recurrent infection, and organ disorders. Individuals with LAs often experience progressively worsening symptoms with a deteriorating quality of life. Although limited treatment options are available, their efficacy has not been validated in prospective clinical trials, and are usually based on case reports. Thus, there are no validated standards of care for these patients because of the lack of prospective clinical trials.

Methods

This open-label, single-arm, multicenter, prospective study will assess the efficacy and safety of a mammalian target of the rapamycin inhibitor sirolimus in the treatment of intractable LAs. Participants will receive oral sirolimus once a day for 52 weeks. The dose is adjusted so that the nadir concentration remains within 5–15 ng/ml. The primary endpoint is the response rate of radiological volumetric change of the target lesion confirmed by central review at 52 weeks after treatment. The secondary endpoints are the response rates at 12 and 24 weeks, respiratory function, pleural effusion, ascites, blood coagulation parameters, bleeding, pain, quality of life, activities of daily living, adverse events, side effects, laboratory examinations, vital signs, and pharmacokinetic data.

Results

This is among the first multicenter studies to evaluate sirolimus treatment for intractable LAs, and few studies to date have focused on the standard assessment of the efficacy for LAs treatment. Our protocol uses novel, uncomplicated methods for radiological assessment, with reference to the results of our previous retrospective survey and historical control data from the literature.

Conclusions

We propose a multicenter study to investigate the efficacy and safety of sirolimus for intractable LAs (SILA study; trial registration UMIN000028905). Our results will provide pivotal data to support the approval of sirolimus for the treatment of intractable LAs.

•

This is among the first multicenter studies to evaluate sirolimus for intractable LAs.

•

The study design is useful for evaluating sirolimus treatment in LAs.

•

Our study protocol uses novel, uncomplicated methods of radiological assessment.

Mycophenolate mofetil contributes to downregulation of the hippocampal interleukin type 2 and 1β mediated PI3K/AKT/mTOR pathway hyperactivation and attenuates neurobehavioral comorbidities in a rat model of temporal lobe epilepsy

The role of neuroinflammatory mediators has been well established in the pathogenesis of temporal lobe epilepsy (TLE) and associated neurobehavioral comorbidities. Mycophenolate mofetil (MMF) is commonly used as an immunosuppressant in organ transplantations. Its neuroprotective effect is well explored in different preclinical and clinical studies. The present study was designed to investigate the effect of MMF in rat model of lithium pilocarpine (LiPc)-induced spontaneous recurrent seizures and its associated neurobehavioral comorbidities. MMF treatment showed a dose-dependent decrease in seizure severity and reduced aggression in epileptic rats. There was marked improvement in spatial and recognition memory functions, along with substantial decrease in depression-like behavior in MMF treated epileptic rats. There was considerable decrease in mossy fiber sprouting in the dentate gyrus and the cornu ammonis 3 regions of the hippocampus, along with reduction in neuronal death in the treated groups. Furthermore, the hippocampal mRNA level of IL-1β, IL-2, PI3K, AKT, HIF-1α, RAPTOR, mTOR, Rps6kb1 and Rps6 was found to be decreased in MMF treated animals. mTOR, S6, pS6 and GFAP protein expression was decreased, whereas NeuN was increased in the rat hippocampus of the treated animals. The results concluded that MMF suppress recurrent seizures, and improves its associated behavioral impairments and cognitive deficit in rat model of TLE. The observed effects of MMF be correlated with the inhibition of IL-2 and IL-1β linked PI3K/AKT/mTOR signaling pathway hyperactivation.

M(en)TORship lessons on life and death by the integrated stress response

Cells employ pro-survival and pro-adaptive pathways to cope with different forms of environmental stress. When stress is excessive, and the damage caused by it is unsustainable, cells engage pro-death pathways, which are in place to protect the host from the deleterious effects of harmed cells. Two important pathways that determine the balance between survival and death of stressed cells are the integrated stress response (ISR) and the mammalian target of rapamycin (mTOR), both of which converge at the level of mRNA translation. The two pathways have established avenues of communication to control their activity and determine the fate of stressed cells in a context-dependent manner. The functional interplay between the ISR and mTOR may have significant ramifications in the development and treatment of human diseases such as diabetes, neurodegeneration and cancer.

Suberoylanilide Hydroxamic Acid Triggers Autophagy by Influencing the mTOR Pathway in the Spinal Dorsal Horn in a Rat Neuropathic Pain Model

Histone acetylation levels can be upregulated by treating cells with histone deacetylase inhibitors (HDACIs), which can induce autophagy. Autophagy flux in the spinal cord of rats following the left fifth lumber spinal nerve ligation (SNL) is involved in the progression of neuropathic pain. Suberoylanilide hydroxamic acid (SAHA), one of the HDACIs can interfere with the epigenetic process of histone acetylation, which has been shown to ease neuropathic pain. Recent research suggest that SAHA can stimulate autophagy via the mammalian target of rapamycin (mTOR) pathway in some types of cancer cells. However, little is known about the role of SAHA and autophagy in neuropathic pain after nerve injury. In the present study, we aim to investigate autophagy flux and the role of the mTOR pathway on spinal cells autophagy activation in neuropathic pain induced by SNL in rats that received SAHA treatment. Autophagy-related proteins and mTOR or its active form were assessed by using western blot, immunohistochemistry, double immunofluorescence staining and transmission electron microscopy (TEM). We found that SAHA decreased the paw mechanical withdrawal threshold (PMWT) of the lower compared with SNL. Autophagy flux was mainly disrupted in the astrocytes and neuronal cells of the spinal cord dorsal horn on postsurgical day 28 and was reversed by daily intrathecal injection of SAHA (n = 100 nmol/day or n = 200 nmol/day). SAHA also decreased mTOR and phosphorylated mTOR (p-mTOR) expression, especially p-mTOR expression in astrocytes and neuronal cells of the spinal dorsal horn. These results suggest that SAHA attenuates neuropathic pain and contributes to autophagy flux in astrocytes and neuronal cells of the spinal dorsal horn via the mTOR signaling pathway.

A low-protein diet eliminates the circadian rhythm of serum insulin and hepatic lipid metabolism in mice

Insulin is a key molecule that synchronizes peripheral clocks, such as that in the liver. Although we previously reported that mice fed a low-protein diet showed altered expression of lipid-related genes in the liver and induction of hepatic steatosis, it is unknown whether a low-protein diet impairs insulin secretion and modifies the hepatic circadian rhythm. Therefore, we investigated the effects of the intake of a low-protein diet on the circadian rhythm of insulin secretion and hepatic lipid metabolism in mice. Under 12-h light/12-h dark cycle, mice fed a low-protein diet for 7 days displayed enhanced food intake at the end of the light phase, although central and peripheral PER2 expression rhythm was maintained. Serum insulin levels in mice fed a low-protein diet remained low during the day, and the insulin secretion in OGTT was also markedly lower than in normal mice. In mice fed low-protein diet, hepatic TG accumulation was observed during the nighttime, with relatively high levels of ACC1 mRNA and total ACC proteins. Although there were no differences in the activity rhythm of hepatic mTOR between mice fed a normal or low-protein diet, hepatic IRS-2 expression in mice fed a low-protein diet remained low during the day, with no increase at the beginning of the light period. These results suggested that the low-protein diet eliminated the circadian rhythm of serum insulin and hepatic lipid metabolism in mice, providing insights into our understanding of the mechanisms of hepatic disorders of lipid metabolism.

Anti-angiogenic effects of valproic acid in a mouse model of oxygen-induced retinopathy

Pathological retinal angiogenesis contributes to the pathogenesis of several ocular diseases. Valproic acid, a widely used antiepileptic drug, exerts anti-angiogenic effects by inhibiting histone deacetylase (HDAC). Herein, we investigated the effects of valproic acid and vorinostat, a HDAC inhibitor, on pathological retinal angiogenesis in mice with oxygen-induced retinopathy (OIR). OIR was induced in neonatal mice by exposure to 80% oxygen from postnatal day (P) 7 to P10 and to atmospheric oxygen from P10 to P15. Mice were subcutaneously injected with valproic acid, vorinostat, or vehicle once a day from P10 to P14. At P15, retinal neovascular tufts and vascular growth in the central avascular zone were observed in mice with OIR. Additionally, immunoreactivity for phosphorylated ribosomal protein S6 (pS6), an indicator of mammalian target of rapamycin (mTOR) activity, was detected in the neovascular tufts. Both valproic acid and vorinostat reduced the formation of retinal neovascular tuft without affecting vascular growth in the central avascular zone. Valproic acid reduced the pS6 immunoreactivity in neovascular tufts. Given that vascular endothelial growth factor (VEGF) activates mTOR-dependent pathways in proliferating endothelial cells of the neonatal mouse retina, these results suggest that valproic acid suppresses pathological retinal angiogenesis by interrupting VEGF-mTOR pathways.

The Anticancer Effect of Huaier Extract in Renal Cancer 786-O Cells

BACKGROUND

Trametes robiniophila Murr (Huaier) has been used as an adjuvant therapy of tumor in traditional Chinese medicine for many years, but the underlying mechanisms are largely unknown. In the present study, we tested the inhibitory effect of Huaier extract on renal cancer 786-O cells and explored the possible mechanisms.

METHODS

786-O cells were treated by gradient concentrations of Huaier extract, cell viability, invasion, migration and apoptosis were assessed by cell counting kit 8, cell scratch, transwell, and flow cytometry assay in vitro. The changes in protein level were detected by western blot analysis. Finally, the anticancer effect of Huaier was tested in vivo by nude mouse tumorigenicity assay.

RESULTS

Viability of 786-O cells was suppressed by Huaier in a time- and dose-dependent manner; cell invasion and migration were also dramatically inhibited. Flow cytometry assays showed that Huaier could induce cell apoptosis. Western blotting analysis indicated that Huaier suppressed the activation of PI3K/AKT/mTOR/p70S6K/4E-BP1 signaling pathway. We also found that Huaier could partly reverse the epithelialmesenchymal transition (EMT) process. In vivo experiment indicated that tumor growth in the xenograft mouse model was suppressed by Huaier.

CONCLUSION

Huaier plays an anticancer effect partially through the suppression of the PI3K/AKT/mTOR/p70S6K/4E-BP1 pathway and by reversing the EMT process. Huaier may act as an effective agent for treating renal cell carcinoma.

The impact of mammalian target of rapamycin inhibition on bone health in postmenopausal women with hormone receptor-positive advanced breast cancer receiving everolimus plus exemestane in the phase IIIb 4EVER trial

Background

Breast cancer and its treatments are associated with a detrimental effect on bone health. Here we report the results of an exploratory analysis assessing changes in levels of biomarkers of bone metabolism in patients enrolled in the phase IIIb 4EVER study.

Methods

The 4EVER trial investigated everolimus in combination with exemestane in postmenopausal women with hormone receptor-positive, human epidermal growth factor receptor 2-negative locally advanced or metastatic breast cancer. In this prespecified exploratory analysis, changes in biomarkers of bone turnover were assessed in patients from baseline to weeks 4, 12, and 24. The serum bone markers assessed were procollagen type 1 N-terminal propeptide (P1NP), C-terminal cross-linking telopeptide of type 1 collagen (CTX), osteocalcin, parathyroid hormone (PTH), and 25-hydroxyvitamin D (25-OH-vitamin D). On-treatment changes in bone markers over time were described per subgroup of interest and efficacy outcomes.

Results

Bone marker data were available for 241 of 299 enrolled patients. At the final assessment, P1NP, osteocalcin, PTH, 25-OH-vitamin D (all P < 0.001), and CTX (P = 0.036) were significantly decreased from baseline values per the Wilcoxon signed-rank test. At the last assessment (24 weeks or earlier), levels of serum CTX and PTH were significantly lower (P = 0.009 and P = 0.034, respectively) among patients with vs. without prior antiresorptive treatment (ART). Serum CTX levels were significantly lower (P < 0.001), and 25-OH-vitamin D concentrations significantly higher (P = 0.029), at the last postbaseline assessment in patients receiving concomitant ART vs. those without ART. Changes from baseline in PTH and 25-OH-vitamin D concentrations to the final assessment were significantly smaller in patients with prior ART. Lower baseline serum concentrations of osteocalcin and PTH were associated with clinical response (partial vs. non-response) at 24 weeks. High serum levels of CTX and P1NP at baseline were risk factors for progression at 12 weeks.

Conclusions

These exploratory analyses support use of everolimus plus exemestane for the treatment of postmenopausal women with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer, and add to the body of evidence suggesting a potentially favorable impact of everolimus on bone turnover.

Trial registration

NCT01626222. Registered 22 June 2012, https://clinicaltrials.gov/ct2/show/NCT01626222.

Early intrathecal infusion of everolimus restores cognitive function and mood in a murine model of Alzheimer's disease

The discovery that mammalian target of rapamycin (mTOR) inhibition increases lifespan in mice and restores/delays many aging phenotypes has led to the identification of a novel potential therapeutic target for the treatment of Alzheimer's disease (AD). Among mTOR inhibitors, everolimus, which has been developed to improve the pharmacokinetic characteristics of rapamycin, has been extensively profiled in preclinical and clinical studies as anticancer and immunosuppressive agent, but no information is available about its potential effects on neurodegenerative disorders. Using a reliable mouse model of AD (3 × Tg-AD mice), we explored whether short-term treatment with everolimus injected directly into the brain by osmotic pumps was able to modify AD-like pathology with low impact on peripheral organs. We first established in non-transgenic mice the stability of everolimus at 37 °C in comparison with rapamycin and, then, evaluated its pharmacokinetics and pharmacodynamics profiles through either a single peripheral (i.p.) or central (i.c.v.) route of administration. Finally, 6-month-old (symptomatic phase) 3 × Tg-AD mice were treated with continuous infusion of either vehicle or everolimus (0.167 μg/μl/day, i.c.v.) using the osmotic pumps. Four weeks after the beginning of infusion, we tested our hypothesis following an integrated approach, including behavioral (tests for cognitive and depressive-like alterations), biochemical and immunohistochemical analyses. Everolimus (i) showed higher stability than rapamycin at 37 °C, (ii) poorly crossed the blood-brain barrier after i.p. injection, (iii) was slowly metabolized in the brain due to a longer t_1/2 in the brain compared to blood, and (iv) was more effective in the CNS when administered centrally compared to a peripheral route. Moreover, the everolimus-induced mTOR inhibition reduced human APP/Aβ and human tau levels and improved cognitive function and depressive-like phenotype in the 3 × Tg-AD mice. The intrathecal infusion of everolimus may be effective to treat early stages of AD-pathology through a short and cyclic administration regimen, with short-term outcomes and a low impact on peripheral organs.

Mesenchymal stem cells-derived IL-6 activates AMPK/mTOR signaling to inhibit the proliferation of reactive astrocytes induced by hypoxic-ischemic brain damage

Mesenchymal stem cells (MSCs) treatment is an effective strategy for the functional repair of central nervous system (CNS) insults through the production of bioactive molecules. We have previously demonstrated that the interleukin-6 (IL-6) secreted by MSCs plays an anti-apoptotic role in injured astrocytes and partly promotes functional recovery in neonatal rats with hypoxic-ischemic brain damage (HIBD). However, the mechanisms of IL-6 underlying the proliferation of injured astrocytes have not been fully elucidated. In this study, we investigated the therapeutic effects of MSCs on astrocyte proliferation in neonatal rats subjected to HIBD. A HIBD model was established in Sprague Dawley (SD) rats, and MSCs were administered by intracerebroventricular injection 5 days after HIBD. Rat primary astrocytes were cultured, subjected to oxygen glucose deprivation (OGD) injury and then immediately co-cultured with MSCs in vitro. Immunofluorescence staining, Cell Counting Kit (CCK)-8, flow cytometry, Ca²⁺ imaging, enzyme-linked immunosorbent assay (ELISA), western blotting, and co-immunoprecipitation (Co-IP) were performed. We found that MSCs transplantation not only promoted the recovery of learning and memory function in HIBD rats but also significantly reduced the number of Ki67⁺/glial fibrillary acidic protein (GFAP)⁺ cells in the hippocampi 7-14 days after HIBD. In addition to increasing IL-6 expression in both the hippocampi of HIBD rats and astrocyte culture medium, MSCs treatment in vitro significantly increased the expression levels of glycoprotein (gp) 130 and phosphorylated AMP-activated protein kinase α (p-AMPKα) and decreased the expression levels of p-mammalian target of rapamycin (mTOR) and its downstream targets. Furthermore, MSCs treatment induced a protein-protein interaction between gp130 and p-AMPKα. Suppression of IL-6 expression in MSCs reversed the above regulatory functions of MSCs in hippocampal astrocytes. The utilization of rapamycin further confirmed that mTOR participated in the proliferation of reactive astrocytes. These findings suggest that endogenous IL-6 produced by MSCs in the HIBD microenvironment provides therapeutic advantages by activating AMPK/mTOR signaling, thus reducing the proliferation of reactive astrocytes.

Clinical significance of Th17 cells in kidney transplantation

Transplantation research has focused on cytotoxic T-cell and plasma cell/B-cell-targeted strategies, but little attention has been paid to the role of T helper 17 (Th17) cells in allograft dysfunction. However, accumulating evidence suggests that Th17 cells contribute to the development of acute and chronic allograft injury after transplantation of various organs, including the kidney. This review summarizes recent reports on the role of Th17 cells in kidney transplantation. Means of improving allograft outcomes by targeting the Th17 pathway are also suggested.

Metformin in cancer

Metformin is a lipophilic biguanide which inhibits hepatic gluconeogenesis and improves peripheral utilization of glucose. It is the first line pharmacotherapy for glucose control in patients with Type 2 diabetes due to its safety, efficacy and tolerability. Metformin exhibits pleotropic effects, which may have beneficial effects on a variety of tissues independent of glucose control. A potential anti-tumourigenic effect of metformin may be mediated by its role in activating AMP-kinase, which in turn inhibits mammalian target of rapamycin (mTOR). Non-AMPK dependent protective pathways may include reduction of insulin, insulin-like growth factor-1, leptin, inflammatory pathways and potentiation of adiponectin, all of which may have a role in tumourigenesis. A role in inhibiting cancer stem cells is also postulated. A number of large scale observational and cohort studies suggest metformin is associated with a reduced risk of a number of cancers, although the data is not conclusive. Recent randomised studies reporting use of metformin in treatment of cancer have revealed mixed results, and the results of much larger randomised trials of metformin as an adjuvant therapy in breast and colorectal cancers are awaited.

Akt and mTORC1 signaling as predictive biomarkers for the EGFR antibody nimotuzumab in glioblastoma

Glioblastoma (GB) is the most frequent primary brain tumor in adults with a dismal prognosis despite aggressive treatment including surgical resection, radiotherapy and chemotherapy with the alkylating agent temozolomide. Thus far, the successful implementation of the concept of targeted therapy where a drug targets a selective alteration in cancer cells was mainly limited to model diseases with identified genetic drivers. One of the most commonly altered oncogenic drivers of GB and therefore plausible therapeutic target is the epidermal growth factor receptor (EGFR). Trials targeting this signaling cascade, however, have been negative, including the phase III OSAG 101-BSA-05 trial. This highlights the need for further patient selection to identify subgroups of GB with true EGFR-dependency. In this retrospective analysis of treatment-naïve samples of the OSAG 101-BSA-05 trial cohort, we identify the EGFR signaling activity markers phosphorylated PRAS40 and phosphorylated ribosomal protein S6 as predictive markers for treatment efficacy of the EGFR-blocking antibody nimotuzumab in MGMT promoter unmethylated GBs. Considering the total trial population irrespective of MGMT status, a clear trend towards a survival benefit from nimotuzumab was already detectable when tumors had above median levels of phosphorylated ribosomal protein S6. These results could constitute a basis for further investigations of nimotuzumab or other EGFR- and downstream signaling inhibitors in selected patient cohorts using the reported criteria as candidate predictive biomarkers.

Silent Information Regulator 1 Negatively Regulates Atherosclerotic Angiogenesis via Mammalian Target of Rapamycin Complex 1 Signaling Pathway

BACKGROUND

This study aimed to investigate the interactions between silent information regulator 1 (SIRT1) and mammalian target of rapamycin (mTOR) in intraplaque angiogenesis and their potential mechanisms through in vivo and in vitro studies.

METHODS

An atherosclerosis model was established in 12 rabbits on a high-cholesterol diet. The rabbits were equally divided into 3 groups: a control group (high-lipid diet), RAP group (high-lipid diet supplemented with rapamycin) and RAP + NAM group (high-lipid diet supplemented with rapamycin and nicotinamide). At the end of 4 weeks, the area of plaques in the aorta was determined and the protein expression of CD31 and vascular endothelial growth factor (VEGF) was detected through hematoxylin and eosin staining and immunohistochemical staining, respectively. For in vitro study, a hypoxia model was established in human umbilical vein endothelial cells (HUVECs) by using the chemical method (CoCl₂). The MTT assay, scratch assay and tube formation assay were performed to evaluate the proliferation and angiogenesis abilities of HUVECs. Reverse transcription polymerase chain reaction was used to examine the mRNA levels of SIRT1, hypoxia-inducible factor-1α (HIF-1α), mTOR and p70 ribosomal S6 kinase (p70S6K). Western blotting was used to examine the protein levels of SIRT1, HIF-1α, mTOR, p-mTOR, p-raptor and p-p70S6K.

RESULTS

The results of the in vivo study indicated a significant inhibitory effect of rapamycin on plaque size and intraplaque angiogenesis (0.05 ± 0.02mm² versus 5.44 ± 0.50mm², P < 0.05). This effect was attenuated by nicotinamide (0.76 ± 0.15mm² versus 0.05 ± 0.02mm², P < 0.05). Compared with the RAP group, CD31- and VEGF-positive vessels were abundant in the RAP + NAM group. The RAP group showed lower expression of p-mTOR, p-p70S6K and HIF-1α than did the control group (P < 0.05), whereas the RAP + NAM group showed slightly higher expression of these factors than did the RAP group (P < 0.05). Furthermore, in vitro studies revealed that the inhibitory effect of rapamycin on the angiogenic ability of HUVECs and its significant inhibitory effects on the protein level of HIF-1α and the phosphorylation of proteins involved in the mTORC1 pathway, including mTOR, raptor and p70S6K (P < 0.05), were enhanced by cotreatment with SRT1720 and rapamycin (P < 0.05). In contrast to mTOR and SIRT1, the mRNA levels of p70S6K and HIF-1α were reduced by rapamycin (P < 0.05) and further reduced by cotreatment with SRT1720 and rapamycin.

CONCLUSIONS

The study results indicate that SIRT1 might negatively regulate atherosclerotic angiogenesis via mTORC1 and HIF-1α signaling pathway and cointervention of SIRT1 and mTOR may serve as a crucial therapeutic strategy in cardiovascular medicine.

Blocking Mammalian Target of Rapamycin (mTOR) Alleviates Neuropathic Pain Induced by Chemotherapeutic Bortezomib

BACKGROUND/AIMS

Bortezomib (BTZ) is largely used as a chemotherapeutic agent for the treatment of cancer. However, one of the significant limiting complications of BTZ is painful peripheral neuropathy during BTZ therapy. Drugs preventing and/or treating the painful symptoms induced by BTZ are lacking since the underlying mechanisms leading to neuropathic pain remain largely unclear. The purposes of this study were to examine 1) the effects of blocking mammalian target of rapamycin (mTOR) on mechanical pain and cold hypersensitivity evoked by BTZ and 2) the underlying mechanisms responsible for the role of mTOR in regulating BTZ-induced neuropathic pain.

METHODS

Behavioral test was performed to determine mechanical pain and cold sensitivity in a rat model. Western blot analysis and ELISA were used to examine expression of mTOR and phosphatidylinositide 3-kinase (p-PI3K) signals, and the levels of substance P and calcitonin gene-related peptide (CGRP).

RESULTS

Systemic injection of BTZ significantly increased mechanical pain and cold sensitivity as compared with control animals (P< 0.05 vs. control rats). The expression of p-mTOR, mTOR-mediated phosphorylation of p70 ribosomal S6 protein kinase 1 (p-S6K1), 4E-binding protein 4 (p-4E-BP1) as well as p-PI3K was amplified in the dorsal horn of spinal cord of BTZ rats as compared with control rats. Blocking mTOR by intrathecal infusion of rapamycin attenuated mechanical pain and cold hypersensitivity. Blocking PI3K signal also attenuated activities of mTOR, which was accompanied with decreasing neuropathic pain. Inhibition of either mTOR or PI3K blunted enhancement of the spinal substance P and CGRP in BTZ rats.

CONCLUSIONS

The data for the first time revealed specific signaling pathways leading to BTZ-induced peripheral neuropathic pain, including the activation of mTOR and PI3K. Inhibition of these signal pathways alleviates pain. Targeting one or more of these signaling molecules may present new opportunities for treatment and management of peripheral painful neuropathy observed during chemotherapeutic application of BTZ.

A comparison of LKB1/AMPK/mTOR metabolic axis response to global ischaemia in brain, heart, liver and kidney in a rat model of cardiac arrest

BACKGROUND

Cellular energy failure in high metabolic rate organs is one of the underlying causes for many disorders such as neurodegenerative diseases, cardiomyopathies, liver and renal failures. In the past decade, numerous studies have discovered the cellular axis of LKB1/AMPK/mTOR as an essential modulator of cell homeostasis in response to energy stress. Through regulating adaptive mechanisms, this axis adjusts the energy availability to its demand by a systematized control on metabolism. Energy stress, however, could be sensed at different levels in various tissues, leading to applying different strategies in response to hypoxic insults.

METHODS

Here the immediate strategies of high metabolic rate organs to time-dependent short episodes of ischaemia were studied by using a rat model (n = 6/group) of cardiac arrest (CA) (15 and 30 s, 1, 2, 4 and 8 min CA). Using western blot analysis, we examined the responses of LKB1/AMPK/mTOR pathway in brain, heart, liver and kidney from 15 s up to 8 min of global ischaemia. The ratio of ADP/ATP was assessed in all ischemic and control groups, using ApoSENSOR bioluminescent assay kit.

RESULTS

Brain, followed by kidney showed the early dephosphorylation response in AMPK (Thr172) and LKB1 (Ser431); in the absence of ATP decline (ADP/ATP elevation). Dephosphorylation of AMPK was followed by rephosphorylation and hyperphosphorylation, which was associated with a significant ATP decline. While heart's activity of AMPK and LKB1 remained at the same level during short episodes of ischaemia, liver's LKB1 was dephosphorylated after 2 min. AMPK response to ischaemia in liver was mainly based on an early alternative and a late constant hyperphosphorylation. No significant changes was observed in mTOR activity in all groups.

CONCLUSION

Together our results suggest that early AMPK dephosphorylation followed by late hyperphosphorylation is the strategy of brain and kidney in response to ischaemia. While the liver seemed to get benefit of its AMPK system in early ischameia, possibly to stabilize ATP, the level of LKB1/AMPK activity in heart remained unchanged in short ischaemic episodes up to 8 min. Further researches must be conducted to elucidate the molecular mechanism underlying LKB1/AMPK response to oxygen supply.