Resveratrol prevents rapamycin-induced upregulation of autophagy and selectively induces apoptosis in TSC2-deficient cells

Safety and Efficacy of Combined Resveratrol and Sirolimus in Lymphangioleiomyomatosis

BACKGROUND

A critical need exists to develop remission-inducing therapies for lymphangioleiomyomatosis.

RESEARCH QUESTION

Is the addition of resveratrol safe and more efficacious than sirolimus alone in patients with lymphangioleiomyomatosis?

STUDY DESIGN AND METHODS

We conducted a phase 2, dose-escalating, open-label trial of resveratrol in patients with lymphangioleiomyomatosis receiving a stable regimen of sirolimus. Resveratrol was started at 250 mg/d and escalated every 8 weeks to maximum dose of 1,000 mg/d over 24 weeks. The primary outcome was ≥ 42% decline in serum vascular endothelial growth factor D (VEGF-D) levels on combined therapy compared with baseline VEGF-D levels on sirolimus. Secondary objectives included an assessment of the safety profile and the effect on lung function and health-related quality of life (HRQOL). Longitudinal change in outcome measures was assessed using linear mixed models. Adverse effects were tabulated using the National Cancer Institute's Common Terminology Criteria for Adverse Events version 4.

RESULTS

Twenty-five patients with lymphangioleiomyomatosis with a median age of 51 years were enrolled. Pulmonary function parameters at study inclusion were: FEV1: median absolute, 1.72 L; 64% predicted; FVC: median absolute, 2.99 L; 96% predicted; and diffusing capacity of the lungs for carbon monoxide: median absolute, 14.68 mL/mm Hg/min; 37% predicted. The median serum VEGF-D value at baseline was 617 pg/mL. Patients entered the study with a median sirolimus dose of 2 mg/d with median trough level of 6.3 ng/mL. Despite some GI side effects, the addition of resveratrol was well tolerated. Although the primary outcome was not met, a statistically significant reduction in serum VEGF-D levels and improvement in HRQOL during the study was found.

INTERPRETATION

The addition of resveratrol was safe and well tolerated in patients with lymphangioleiomyomatosis taking sirolimus and was associated with modest improvement in HRQOL. Larger controlled trials of this combination might be warranted to assess definitively the usefulness of resveratrol as an additive therapy in lymphangioleiomyomatosis.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03253913; URL: www.

CLINICALTRIALS

gov.

MiR-155 Dysregulation Is Associated with the Augmentation of ROS/p53 Axis of Fibrosis in Thioacetamide-Induced Hepatotoxicity and Is Protected by Resveratrol

Liver fibrosis is a hallmark of thioacetamide (TAA) intoxications. MicroRNAs (miRs), such as miR-155, have been implied in the pathogenesis of liver disease, and regulated by the antioxidant and anti-inflammatory compound resveratrol (RES). The link between reactive oxygen species (ROS), tumour suppressor p53 (p53), and liver fibrosis-during the pathogenesis of TAA-induced liver injury-associated with miR-155 dysregulation with and without RES incorporation has not been previously studied. Therefore, one group of rats received TAA injections of 200 mg/kg; twice a week at the beginning of week 3 for 8 weeks (TAA group; or model group), whereas the protective group was pretreated daily with RES suspension (20 mg/kg; orally) for the first two weeks and subsequently sustained on receiving both RES and TAA until being sacrificed at the 10th week. Liver injuries developed in the model group were confirmed by a significant (p < 0.0001) elevation of hepatic tissue levels of miR-155, ROS, p53, and the profibrogenic biomarkers: tissue inhibitor of metalloproteinases-1 and α-smooth muscle actin, as well as collagen deposition (fibrosis). All these parameters were significantly (p ≤ 0.0234) protected by resveratrol (RES + TAA). In addition, we observed a significant (p < 0.0001) correlation between ROS/p53 axis mediated liver fibrosis and miR-155. Thus, TAA intoxication induced miR-155 imbalance and ROS/p53-mediated liver fibrosis, with resveratrol, conversely displaying beneficial hepatic pleiotropic effects for a period of 10 weeks.

Association of resveratrol with the suppression of TNF-α/NF-kB/iNOS/HIF-1α axis-mediated fibrosis and systemic hypertension in thioacetamide-induced liver injury

Chronic liver injury can lead to hepatic failure and the only available method of treatment would be liver transplantation. The link between inflammation (TNF-α), nuclear factor-kappa B (NF-kB), nitrosative stress (iNOS) and hypoxia-inducible factor-1α (HIF-1α) in thioacetamide (TAA) induced liver fibrosis, and hypertension with and without the incorporation of the anti-inflammatory and antioxidant resveratrol (RES) has not been investigated before. Consequently, we injected rats with either 200 mg/kg TAA for 8 weeks starting at week 2 (model group) or pretreated them before TAA injections with RES (20 mg/kg) for 2 weeks and continued them on RES and TAA until being culled at week 10 (protective group). In the model group, we documented the induction of hepatic fibrosis and upregulation of tumor necrosis factor-α (TNF-α), NF-kB, inducible nitric oxide synthase (iNOS), HIF-1α and the profibrotic biomarkers alpha-smooth muscle actin (α-SMA) and matrix metalloproteinase-9 (MMP-9) that was significantly (p ≤ 0.0014) ameliorated by RES. RES also significantly (p ≤ 0.0232) reduced triglycerides (TG), cholesterol (CHOL), very low-density lipoprotein (vLDL-C), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure, and heart rate (HR) induction by TAA. Also, a significant (p < 0.0001) positive correlation between TNF-α/NF-kB/iNOS/HIF-1α axis-mediated fibrosis and hypertension and liver injury biomarkers was observed. These findings suggest that in the hepatotoxic compound, TAA is associated with TNF-α/NF-kB/iNOS/HIF-1α-mediated fibrosis and hypertension, whilst being inhibited by RES.

Autophagy modulation in resveratrol protective effects on steroidogenesis in high-fat diet-fed mice and H2O2-challenged TM3 cells

BACKGROUND

Autophagy dysregulation and oxidative stress play critical pathophysiological roles in developing obesity-related metabolic health disorders. This study aims to investigate how autophagy modulation is related to resveratrol (RSV) antioxidant activities and preventive effects on steroidogenesis decline associated with a high-fat diet (HFD) and oxidative damage.

METHODS AND RESULTS

Eight-week-old C57BL/6 J male mice were fed with HFD with or without supplement RSV (400 mg/kg/day) by gavage for 16 weeks. The control group was fed with a standard diet with no RSV or the same amount of RSV. Mouse Leydig cell line TM3 cell was used for in vitro studies. Oxidative stress was induced in TM3 cells with H₂O₂, followed by RSV treatment plus autophagy activator rapamycin or autophagy inhibitor 3-methyladenine, respectively. RSV supplement could upregulate proteins level of StAR and mitochondrial proteins COX4 and mtTFA, indicating the amelioration of steroidogenesis decline and mitochondrial dysfunction caused by HFD. Antioxidants such as GPx4 and SOD2 were improved by RSV as well. The observation of autophagosomes and the changes in expressions of LC3II/I, Beclin1, and Atg7 indicated that RSV could reverse the autophagy defect associated with HFD. 3-methyladenine inhibition of autophagy partially abolished RSV protection on mitochondrial function and steroidogenesis in H₂O₂-challenged TM3 cells. However, the combination use of rapamycin and RSV did not improve protection on Leydig cells against oxidative damage.

CONCLUSIONS

The stimulation of autophagy by RSV is closely linked to its antioxidant actions and positive impact on steroidogenesis in HFD mice. The findings suggest RSV is protective against obesity-related Leydig cell impairment.

Primary cells derived from Tuberous Sclerosis Complex patients show autophagy alteration in the haploinsufficiency state

Tuberous sclerosis complex (TSC) is an autosomal dominant cancer predisposition disorder caused by heterozygous mutations in TSC1 or TSC2 genes and characterized by mTORC1 hyperactivation. TSC-associated tumors develop after loss of heterozygosity mutations and their treatment involves the use of mTORC1 inhibitors. We aimed to evaluate cellular processes regulated by mTORC1 in TSC cells with different mutations before tumor development. Flow cytometry analyses were performed to evaluate cell viability, cell cycle and autophagy in non-tumor primary TSC cells with different heterozygous mutations and in control cells without TSC mutations, before and after treatment with rapamycin (mTORC1 inhibitor). We did not observe differences in cell viability and cell cycle between the cell groups. However, autophagy was reduced in mutated cells. After rapamycin treatment, mutated cells showed a significant increase in the autophagy process (p=0.039). We did not observe differences between cells with distinct TSC mutations. Our main finding is the alteration of autophagy in non-tumor TSC cells. Previous studies in literature found autophagy alterations in tumor TSC cells or knock-out animal models. We showed that autophagy could be an important mechanism that leads to TSC tumor formation in the haploinsufficiency state. This result could guide future studies in this field.

Targeting of cancer cell death mechanisms by resveratrol: a review

Cancer cell death is the utmost aim in cancer therapy. Anti-cancer agents can induce apoptosis, mitotic catastrophe, senescence, or autophagy through the production of free radicals and induction of DNA damage. However, cancer cells can acquire some new properties to adapt to anti-cancer agents. An increase in the incidence of apoptosis, mitotic catastrophe, senescence, and necrosis is in favor of overcoming tumor resistance to therapy. Although an increase in the autophagy process may help the survival of cancer cells, some studies indicated that stimulation of autophagy cell death may be useful for cancer therapy. Using some low toxic agents to amplify cancer cell death is interesting for the eradication of clonogenic cancer cells. Resveratrol (a polyphenol agent) may affect various signaling pathways related to cell death. It can induce death signals and also downregulate the expression of anti-apoptotic genes. Resveratrol has also been shown to modulate autophagy and induce mitotic catastrophe and senescence in some cancer cells. This review focuses on the important targets and mechanisms for the modulation of cancer cell death by resveratrol.

The Multifaceted Functions of Autophagy in Breast Cancer Development and Treatment

Macroautophagy (herein referred to as autophagy) is a complex catabolic process characterized by the formation of double-membrane vesicles called autophagosomes. During this process, autophagosomes engulf and deliver their intracellular content to lysosomes, where they are degraded by hydrolytic enzymes. Thereby, autophagy provides energy and building blocks to maintain cellular homeostasis and represents a dynamic recycling mechanism. Importantly, the clearance of damaged organelles and aggregated molecules by autophagy in normal cells contributes to cancer prevention. Therefore, the dysfunction of autophagy has a major impact on the cell fate and can contribute to tumorigenesis. Breast cancer is the most common cancer in women and has the highest mortality rate among all cancers in women worldwide. Breast cancer patients often have a good short-term prognosis, but long-term survivors often experience aggressive recurrence. This phenomenon might be explained by the high heterogeneity of breast cancer tumors rendering mammary tumors difficult to target. This review focuses on the mechanisms of autophagy during breast carcinogenesis and sheds light on the role of autophagy in the traits of aggressive breast cancer cells such as migration, invasion, and therapeutic resistance.

Longevity genes, cardiac ageing, and the pathogenesis of cardiomyopathy: implications for understanding the effects of current and future treatments for heart failure

The two primary molecular regulators of lifespan are sirtuin-1 (SIRT1) and mammalian target of rapamycin complex 1 (mTORC1). Each plays a central role in two highly interconnected pathways that modulate the balance between cellular growth and survival. The activation of SIRT1 [along with peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α) and adenosine monophosphate-activated protein kinase (AMPK)] and the suppression of mTORC1 (along with its upstream regulator, Akt) act to prolong organismal longevity and retard cardiac ageing. Both activation of SIRT1/PGC-1α and inhibition of mTORC1 shifts the balance of cellular priorities so as to promote cardiomyocyte survival over growth, leading to cardioprotective effects in experimental models. These benefits may be related to direct actions to modulate oxidative stress, organellar function, proinflammatory pathways, and maladaptive hypertrophy. In addition, a primary shared benefit of both SIRT1/PGC-1α/AMPK activation and Akt/mTORC1 inhibition is the enhancement of autophagy, a lysosome-dependent degradative pathway, which clears the cytosol of dysfunctional organelles and misfolded proteins that drive the ageing process by increasing oxidative and endoplasmic reticulum stress. Autophagy underlies the ability of SIRT1/PGC-1α/AMPK activation and Akt/mTORC1 suppression to extend lifespan, mitigate cardiac ageing, alleviate cellular stress, and ameliorate the development and progression of cardiomyopathy; silencing of autophagy genes abolishes these benefits. Loss of SIRT1/PGC-1α/AMPK function or hyperactivation of Akt/mTORC1 is a consistent feature of experimental cardiomyopathy, and reversal of these abnormalities mitigates the development of heart failure. Interestingly, most treatments that have been shown to be clinically effective in the treatment of chronic heart failure with a reduced ejection fraction have been reported experimentally to exert favourable effects to activate SIRT1/PGC-1α/AMPK and/or suppress Akt/mTORC1, and thereby, to promote autophagic flux. Therefore, the impairment of autophagy resulting from derangements in longevity gene signalling is likely to represent a seminal event in the evolution and progression of cardiomyopathy.

Evaluation of Hsp90 and mTOR inhibitors as potential drugs for the treatment of TSC1/TSC2 deficient cancer

Inactivating mutations in either TSC1 or TSC2 cause Tuberous Sclerosis Complex, an autosomal dominant disorder, characterized by multi-system tumor and hamartoma development. Mutation and loss of function of TSC1 and/or TSC2 also occur in a variety of sporadic cancers, and rapamycin and related drugs show highly variable treatment benefit in patients with such cancers. The TSC1 and TSC2 proteins function in a complex that inhibits mTORC1, a key regulator of cell growth, which acts to enhance anabolic biosynthetic pathways. In this study, we identified and validated five cancer cell lines with TSC1 or TSC2 mutations and performed a kinase inhibitor drug screen with 197 compounds. The five cell lines were sensitive to several mTOR inhibitors, and cell cycle kinase and HSP90 kinase inhibitors. The IC50 for Torin1 and INK128, both mTOR kinase inhibitors, was significantly increased in three TSC2 null cell lines in which TSC2 expression was restored. Rapamycin was significantly more effective than either INK128 or ganetespib (an HSP90 inhibitor) in reducing the growth of TSC2 null SNU-398 cells in a xenograft model. Combination ganetespib-rapamycin showed no significant enhancement of growth suppression over rapamycin. Hence, although HSP90 inhibitors show strong inhibition of TSC1/TSC2 null cell line growth in vitro, ganetespib showed little benefit at standard dosage in vivo. In contrast, rapamycin which showed very modest growth inhibition in vitro was the best agent for in vivo treatment, but did not cause tumor regression, only growth delay.

The paradox of autophagy in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by germline mutations in TSC1 or TSC2 genes, which leads to the hyperactivation of the mTORC1 pathway, an important negative regulator of autophagy. This leads to the development of hamartomas in multiple organs. The variability in symptoms presents a challenge for the development of completely effective treatments for TSC. One option is the treatment with mTORC1 inhibitors, which are targeted to block cell growth and restore autophagy. However, the therapeutic effect of rapamycin seems to be more efficient in the early stages of hamartoma development, an effect that seems to be associated with the paradoxical role of autophagy in tumor establishment. Under normal conditions, autophagy is directly inhibited by mTORC1. In situations of bioenergetics stress, mTORC1 releases the Ulk1 complex and initiates the autophagy process. In this way, autophagy promotes the survival of established tumors by supplying metabolic precursors during nutrient deprivation; paradoxically, excessive autophagy has been associated with cell death in some situations. In spite of its paradoxical role, autophagy is an alternative therapeutic strategy that could be explored in TSC. This review compiles the findings related to autophagy and the new therapeutic strategies targeting this pathway in TSC.

Fanconi anemia and mTOR pathways functionally interact during stalled replication fork recovery

We have previously demonstrated that Fanconi anemia (FA) proteins work in concert with other FA and non-FA proteins to mediate stalled replication fork restart. Previous studies suggest a connection between the FA protein FANCD2 and the non-FA protein mechanistic target of rapamycin (mTOR). A recent study showed that mTOR is involved in actin-dependent DNA replication fork restart, suggesting possible roles in the FA DNA repair pathway. In this study, we demonstrate that during replication stress mTOR interacts and cooperates with FANCD2 to provide cellular stability, mediate stalled replication fork restart, and prevent nucleolytic degradation of the nascent DNA strands. Taken together, this study unravels a novel functional cross-talk between two important mechanisms: mTOR and FA DNA repair pathways that ensure genomic stability.

Chemotherapeutic efficacy of curcumin and resveratrol against cancer: Chemoprevention, chemoprotection, drug synergism and clinical pharmacokinetics

The frequent inefficiency of conventional cancer therapies due to drug resistance, non-targeted drug delivery, chemotherapy-associated toxic side effects turned the focus to bioactive phytochemicals. In this context, curcumin and resveratrol have emerged as potent chemopreventive and chemoprotective compounds modulating apoptotic and autophagic cell death pathways in cancer in vitro and in vivo. As synergistic agents in combination with clinically established anticancer drugs, the enhanced anticancer activity at reduced chemotherapy-associated toxicity towards normal organs can be explained by improved pharmacokinetics, pharmacodynamics, bioavailability and metabolism. With promising preclinical and clinical applications, the design of drug-loaded nanoparticles, nanocarriers, liposomes and micelles have gained much attention to improve target specificity and drug efficacy. The present review focuses on the molecular modes of chemoprevention, chemoprotection and drug synergism with special emphasis to preclinical and clinical applications, pharmacokinetics, pharmacodynamics and advanced drug delivery methods for the development of next-generation personalized cancer therapeutics.

Possible Novel Therapeutic Targets in Lymphangioleiomyomatosis Treatment

Lymphangioleiomyomatosis (LAM) is a rare systemic neoplastic disease that exclusively happens in women. Studies focusing on LAM and tuberous sclerosis complex (TSC) have made great progress in understanding the pathogenesis and searching for treatment. The inactive mutation of TSC1 or TSC2 is found in patients with LAM to activate the crucial mammalian target of rapamycin (mTOR) signaling pathway and result in enhanced cell proliferation and migration. However, it does not explain every step of tumorigenesis in LAM. Because cessation of rapamycin would break the stabilization of lung function or improved quality of life and lead to disease recurrent, continued studies on the pathogenesis of LAM are necessary to identify novel targets and new treatment. Researchers have found several aberrant regulations that affect the mTOR pathway such as its upstream or downstream molecules and compensatory pathways in LAM. Some therapeutic targets have been under study in clinical trials. New methods like genome-wide association studies have located a novel gene related to LAM. Herein, we review the current knowledge regarding pathogenesis and treatment of LAM and summarize novel targets of therapeutic potential recently.

Autophagy suppresses resveratrol-induced apoptosis in renal cell carcinoma 786-O cells

As a polyphenolic compound, resveratrol (Res) is widely distributed in a variety of plants. Previous studies have demonstrated that Res can inhibit various different types of tumor growth. However, its role in renal cell carcinoma (RCC) remains largely unknown. The present study first demonstrated that Res inhibited cell viability and induced apoptosis in RCC 786-O cells. Further experiments revealed that Res damaged the mitochondria and activated caspase 3. In contrast, Z-VAD-FMK, a pan-caspase inhibitor, suppressed Res-induced apoptosis. Reactive oxygen species (ROS) were involved in the process of Res-induced apoptosis, and antioxidant N-acetyl cysteine could significantly attenuate this. Furthermore, Res activated c-Jun N-terminal kinase via ROS to induce autophagy, whereas inhibition of autophagy with chloroquine or Beclin 1 small interfering RNA aggravated Res-induced apoptosis, indicating that autophagy served as a pro-survival mechanism to protect 786-O cells from Res-induced apoptosis. Therefore, a combination of Res and autophagy inhibitors could enhance the inhibitory effect of Res on RCC.

Estrogen activates pyruvate kinase M2 and increases the growth of TSC2-deficient cells

Lymphangioleiomyomatosis (LAM) is a devastating lung disease caused by inactivating gene mutations in either TSC1 or TSC2 that result in hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1). As LAM occurs predominantly in women during their reproductive age and is exacerbated by pregnancy, the female hormonal environment, and in particular estrogen, is implicated in LAM pathogenesis and progression. However, detailed underlying molecular mechanisms are not well understood. In this study, utilizing human pulmonary LAM specimens and cell culture models of TSC2-deficient LAM patient-derived and rat uterine leiomyoma-derived cells, we tested the hypothesis that estrogen promotes the growth of mTORC1-hyperactive cells through pyruvate kinase M2 (PKM2). Estrogen increased the phosphorylation of PKM2 at Ser37 and induced the nuclear translocation of phospho-PKM2. The estrogen receptor antagonist Faslodex reversed these effects. Restoration of TSC2 inhibited the phosphorylation of PKM2 in an mTORC1 inhibitor-insensitive manner. Finally, accumulation of phosphorylated PKM2 was evident in pulmonary nodule from LAM patients. Together, our data suggest that female predominance of LAM might be at least in part attributed to estrogen stimulation of PKM2-mediated cellular metabolic alterations. Targeting metabolic regulators of PKM2 might have therapeutic benefits for women with LAM and other female-specific neoplasms.

Functional interaction between Fanconi anemia and mTOR pathways during stalled replication fork recovery.. [DOI: 10.1101/2020.01.16.899211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

We have previously demonstrated that Fanconi Anemia (FA) proteins work in concert with other FA and non-FA proteins to mediate stalled replication fork restart. Previous studies suggest a connection between FA protein FANCD2 and a non-FA protein mechanistic target of rapamycin (mTOR). A recent study showed that mTOR is involved in actin-dependent DNA replication fork restart, suggesting possible roles in FA DNA repair pathway. In this study, we demonstrate that during replication stress mTOR interacts and cooperates with FANCD2 to provide cellular stability, mediates stalled replication fork restart and prevents nucleolytic degradation of the nascent DNA strands. Taken together, this study unravels a novel functional cross-talk between two important mechanisms: mTOR and FA DNA repair pathways that ensure genomic stability.

Resveratrol Activates Neuronal Autophagy Through AMPK in the Ischemic Brain

During cerebral ischemia, oxygen and glucose levels decrease, producing many consequences such as the generation of reactive oxygen species, tissue injury, and the general metabolism collapse. Resveratrol triggers signaling dependent on the protein kinase activated by adenosine monophosphate (AMPK), the sensor of cellular energy metabolism that regulates autophagy, eliminates damaged mitochondria, and increases energy sources. In the present study, we investigated the participation of AMPK activation in the protective effect of resveratrol on cerebral ischemia and excitotoxicity. We found that resveratrol increased the levels of phosphorylated AMPK in the cerebral cortex of rats subjected to middle cerebral artery occlusion (MCAO) and in primary cultured neurons exposed to glutamate-induced excitotoxicity. Resveratrol (1.8 mg/Kg; i. v.; administered at the beginning of reperfusion) decreased the infarct area and increased survival of rats subjected to MCAO. In neuronal cultures, resveratrol treatment (40 μM, after excitotoxicity) reduced the production of superoxide anion, prevented the overload of intracellular Ca⁺² associated to mitochondrial failure, reduced the release of the lactate dehydrogenase enzyme, and reduced death. It also promoted mitophagy (increased Beclin 1 level, favored the recruitment of LC3-II, reduced LAMP1, and reduced mitochondrial matrix protein HSP60 levels). In both models, inhibition of AMPK activation with Compound C obstructed the effect of resveratrol, showing that its protective effect depends, partially, on the activation of the AMPK/autophagy pathway.

JNK1 regulates RANKL-induced osteoclastogenesis via activation of a novel Bcl-2-Beclin1-autophagy pathway

JNK1 plays an important role in osteoclastogenesis in response to the osteoclastogenic cytokine receptor activator for nuclear factor-κB ligand (RANKL). JNK1 is widely accepted as an autophagy regulator under stress conditions. However, the role of JNK1-mediated autophagy in osteoclastogenesis remains largely unknown. In the current study, our data showed that JNK1 inhibition by a pharmacological inhibitor or RNA interference significantly reduced the autophagic response induced by RANKL in osteoclast precursors (OCPs) derived from bone marrow-derived macrophages. Overexpression of the key autophagy protein Beclin1 rescued autophagy deficiency and osteoclastogenesis in the presence of a JNK inhibitor (SP600125). In contrast, JNK activator (anisomycin)-induced autophagy was blocked by Beclin1 knockdown in OCPs. In addition, JNK1 inhibition increased apoptosis and blocked autophagy, whereas overexpression of Beclin1 reversed the enhanced apoptosis induced by JNK1 inhibition in OCPs. Furthermore, RANKL could induce the phosphorylation of Bcl-2, subsequently dissociating Beclin1 from the Bcl-2-Beclin1 complex, which could be blocked by JNK1 inhibition. Collectively, this study revealed that JNK1 regulated osteoclastogenesis by activating Bcl-2-Beclin1-autophagy signaling in addition to the classic c-Jun/activator protein 1 pathway, which provided the first evidence for the contribution of JNK1 signaling to OCP autophagy and the autophagic mechanism underlying JNK1-regulated osteoclastogenesis. An important osteoclastogenesis-regulating signaling pathway (JNK1-Bcl-2-Beclin1-autophagy activation) was identified, which provides novel potential targets for the clinical therapy of metabolic bone diseases.-Ke, D., Ji, L., Wang, Y., Fu, X., Chen, J., Wang, F., Zhao, D., Xue, Y., Lan, X., Hou, J. JNK1 regulates RANKL-induced osteoclastogenesis via activation of a novel Bcl-2-Beclin1-autophagy pathway.

Recent advances in the pathobiology and clinical management of lymphangioleiomyomatosis

PURPOSE OF REVIEW

Lymphangioleiomyomatosis (LAM) is a rare systemic disease that occurs almost exclusively in women. In the last few years, our understanding of disease pathobiology has improved substantially; in addition, a guideline document has recently been developed that provides recommendations for the diagnosis and clinical management of patients with LAM. Yet, significant gaps in knowledge remain.

RECENT FINDINGS

Groundbreaking insights into the cellular biochemistry of LAM have led to the reclassification of the disease as a low-grade, destructive, metastasizing neoplasm. In addition, recent data confirm the potential of next-generation sequencing to detect low-prevalence mutations in tuberous sclerosis (TSC) genes in sporadic LAM. A randomized, double-blind, multicentre trial has confirmed the efficacy of sirolimus in stabilizing lung function, improving functional performance and quality of life, and reducing lymphatic manifestations in patients with LAM. Accordingly, recent guidelines issued by the American Thoracic Society and the Japanese Respiratory Society recommend sirolimus treatment for patients with LAM and reduced lung function. Uncertainty remains, however, with regard to patient selection, and timing of initiation, duration and dosing of treatment.

SUMMARY

Significant advances have been made in the diagnosis and clinical management of patients with LAM. However, additional studies are needed to assess long-term safety and efficacy of sirolimus therapy, and to identify predictors of disease behaviour and response to treatment.

Curcumin and resveratrol suppress dextran sulfate sodium‑induced colitis in mice

Curcumin and resveratrol are two natural products, which have been described as potential anti‑inflammatory, anti‑tumor, and anti‑oxidant molecules. The aims of the present study were to investigate the protective effect of curcumin and resveratrol on dextran sulfate sodium (DSS)‑induced ulcerative colitis (UC) in mice, in addition to understanding the underlying molecular mechanisms. In order to accomplish this, BALB/c mice received drinking water containing 3.5% DSS. Curcumin (50 mg/kg/day) or resveratrol (80 mg/kg/day) were administered orally for 7 days. Survival rate, body weight, disease activity index score, colon length, pro‑inflammatory cytokines, and the expression autophagy‑associated proteins, and mechanistic target of rapamycin (mTOR) and sirtuin 1 (SIRT1) were measured. Curcumin or resveratrol treatment prolonged the survival of mice with UC, reduced body weight loss and attenuated the severity of the disease compared with the DSS‑treated mice. This effect was associated with a substantial clinical amelioration of the disruption of the colonic architecture and a significant reduction in pro‑inflammatory cytokine production. Furthermore, curcumin or resveratrol significantly downregulated the expression of autophagy‑related 12, Beclin‑1 and microtubule‑associated protein light chain 3 II, and upregulated the expression of phosphorylated mTOR and SIRT1 in the colon tissue, compared with those in the DSS‑treated group. These results suggest that curcumin and resveratrol exert protective effects on DSS‑induced UC, partially through suppressing the intestinal inflammatory cascade reaction, reducing autophagy and regulating SIRT1/mTOR signaling.

Autophagy in Human Health and Disease: Novel Therapeutic Opportunities

SIGNIFICANCE

In eukaryotes, autophagy represents a highly evolutionary conserved process, through which macromolecules and cytoplasmic material are degraded into lysosomes and recycled for biosynthetic or energetic purposes. Dysfunction of the autophagic process has been associated with the onset and development of many human chronic pathologies, such as cardiovascular, metabolic, and neurodegenerative diseases as well as cancer. Recent Advances: Currently, comprehensive research is being carried out to discover new therapeutic agents that are able to modulate the autophagic process in vivo. Recent evidence has shown that a large number of natural bioactive compounds are involved in the regulation of autophagy by modulating several transcriptional factors and signaling pathways.

CRITICAL ISSUES

Critical issues that deserve particular attention are the inadequate understanding of the complex role of autophagy in disease pathogenesis, the limited availability of therapeutic drugs, and the lack of clinical trials. In this context, the effects that natural bioactive compounds exert on autophagic modulation should be clearly highlighted, since they depend on the type and stage of the pathological conditions of diseases.

FUTURE DIRECTIONS

Research efforts should now focus on understanding the survival-supporting and death-promoting roles of autophagy, how natural compounds interact exactly with the autophagic targets so as to induce or inhibit autophagy and on the evaluation of their pharmacological effects in a more in-depth and mechanistic way. In addition, clinical studies on autophagy-inducing natural products are strongly encouraged, also to highlight some fundamental aspects, such as the dose, the duration, and the possible synergistic action of these compounds with conventional therapy.

Leukemia growth is inhibited by benzoxime without causing any harmful effect in rats bearing RBL-1 ×enotransplants

The present study aimed to investigate the effect of benzoxime on leukemia RBL-1 cell proliferation and a leukemic Sprague-Dawley rat model. Proliferation of RBL-1 cells was determined using an MTT assay. Sprague-Dawley rats were assigned randomly into three groups of 10 animals each, where the positive control group was administered an intravenous injection of normal saline, the negative control group was administered 1×10⁶ RBL-1 cells and the treatment group was administered with 1×10⁶ RBL-1 cells and then benzoxime (50 mg/kg/day) for 1 week. Increased dosage of benzoxime reduced RBL-1 cell viability from 92 at 2 µM to ٢١٪ at ١٢ µM after ٢٤ h. Benzoxime treatment prevented the loss of body weight in the rats with leukemia. Compared with the negative control rats, the body weight was determined to be significantly reduced (P<0.05) in the positive control rats. The weight of the spleen and liver was determined to be significantly increased (P<0.02) in the positive control rats and the benzoxime-treated rats compared with that in the negative control group on day 35 of RBL-1 cell implantation. Analysis of leukocytes in rats on day 35 demonstrated a significant reduction (P<0.05) in the cluster of differentiation (CD)11b and CD45 level in the positive control group compared with that in the negative control group. The level of CD11b and CD45 was determined to be similar in the rats in the benzoxime treatment and negative control groups. Analysis of the level of serum glutamic pyruvic transaminase, serum glutamic oxaloacetic transaminase and blood urea nitrogen indicated that all three components exhibited no significant changes in the rats following treatment with benzoxime compared with the component levels in the negative control group. The levels of these three components were in the normal range in rats treated with benzoxime on day 35 of cell implantation. These data demonstrated that the liver and kidneys are not influenced by benzoxime in rats with leukemia. In summary, the present study demonstrated that benzoxime efficiently prevents leukemia growth without inducing any harmful effects in rat models through targeting CD11b and CD45 level; thus, benzoxime should be evaluated further regarding its use in the treatment of leukemia.

mTOR Signaling and Neural Stem Cells: The Tuberous Sclerosis Complex Model

The mechanistic target of rapamycin (mTOR), a serine-threonine kinase, plays a pivotal role in regulating cell growth and proliferation. Notably, a great deal of evidence indicates that mTOR signaling is also crucial in controlling proliferation and differentiation of several stem cell compartments. Consequently, dysregulation of the mTOR pathway is often associated with a variety of disease, such as cancer and metabolic and genetic disorders. For instance, hyperactivation of mTORC1 in neural stem cells (NSCs) is associated with the insurgence of neurological manifestation characterizing tuberous sclerosis complex (TSC). In this review, we survey the recent contributions of TSC physiopathology studies to understand the role of mTOR signaling in both neurogenesis and tumorigenesis and discuss how these new insights can contribute to developing new therapeutic strategies for neurological diseases and cancer.

The therapeutic potential of resveratrol: a review of clinical trials

Resveratrol is a nutraceutical with several therapeutic effects. It has been shown to mimic effects of caloric restriction, exert anti-inflammatory and anti-oxidative effects, and affect the initiation and progression of many diseases through several mechanisms. While there is a wealth of in vitro and in vivo evidence that resveratrol could be a promising therapeutic agent, clinical trials must confirm its potential. In this work, we reviewed the current clinical data available regarding the pharmacological action of resveratrol. Most of the clinical trials of resveratrol have focused on cancer, neurological disorders, cardiovascular diseases, diabetes, non-alcoholic fatty liver disease (NAFLD), and obesity. We found that for neurological disorders, cardiovascular diseases, and diabetes, the current clinical trials show that resveratrol was well tolerated and beneficially influenced disease biomarkers. However resveratrol had ambiguous and sometimes even detrimental effects in certain types of cancers and in NAFLD. In most of the clinical trials, the major obstacle presented was resveratrol’s poor bioavailability. Thus, this work provides useful considerations for the planning and design of future pre-clinical and clinical research on resveratrol.

ERRα regulates the growth of triple-negative breast cancer cells via S6K1-dependent mechanism

Estrogen-related receptor alpha (ERRα) is an orphan nuclear factor that is a master regulator of cellular energy metabolism. ERRα is overexpressed in a variety of tumors, including ovarian, prostate, colorectal, cervical and breast, and is associated with a more aggressive tumor and a worse outcome. In breast cancer, specifically, high ERRα expression is associated with an increased rate of recurrence and a poor prognosis. Because of the common functions of ERRα and the mTORC1/S6K1 signaling pathway in regulation of cellular metabolism and breast cancer pathogenesis, we focused on investigating the biochemical relationship between ERRα and S6K1. We found that ERRα negatively regulates S6K1 expression by directly binding to its promoter. Downregulation of ERRα expression sensitized ERα-negative breast cancer cells to mTORC1/S6K1 inhibitors. Therefore, our results show that combinatorial inhibition of ERRα and mTORC1/S6K1 may have clinical utility in treatment of triple-negative breast cancer, and warrants further investigation.

Blackcurrant anthocyanins stimulated cholesterol transport via post-transcriptional induction of LDL receptor in Caco-2 cells

PURPOSES

We previously showed that polyphenol-rich blackcurrant extract (BCE) showed a hypocholesterolemic effect in mice fed a high fat diet. As direct cholesterol removal from the body via the intestine has been recently appreciated, we investigated the effect of BCE on the modulation of genes involved in intestinal cholesterol transport using Caco-2 cells as an in vitro model.

METHODS

Caco-2 cells were treated with BCE to determine its effects on mRNA and protein expression of genes important for intestinal cholesterol transport, low-density lipoprotein (LDL) uptake, cellular cholesterol content, and cholesterol transport from basolateral to apical membrane of Caco-2 cell monolayers. Cells were also treated with anthocyanin-rich or -poor fraction of BCE to determine the role of anthocyanin on BCE effects.

RESULTS

BCE significantly increased protein levels of LDL receptor (LDLR) without altering its mRNA, which consequently increased LDL uptake into Caco-2 cells. This post-transcriptional induction of LDLR by BCE was markedly attenuated in the presence of rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1). In addition, BCE altered genes involved in cholesterol transport in the enterocytes, including apical and basolateral cholesterol transporters, in such a way that could enhance cholesterol flux from the basolateral to apical side of the enterocytes. Indeed, BCE significantly increased the flux of LDL-derived cholesterol from the basolateral to the apical chamber of Caco-2 monolayer. LDLR protein levels were markedly increased by anthocyanin-rich fraction, but not by anthocyanin-free fraction.

CONCLUSION

mTORC1-dependent post-transcriptional induction of LDLR by BCE anthocyanins drove the transport of LDL-derived cholesterol to the apical side of the enterocytes. This may represent a potential mechanism for the hypocholesterolemic effect of BCE.

Recent Advances and Challenges of mTOR Inhibitors Use in the Treatment of Patients with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a genetic condition characterized by the presence of benign, noninvasive, and tumor-like lesions called hamartomas that can affect multiple organ systems and are responsible for the clinical features of the disease. In the majority of cases, TSC results from mutations in the TSC1 and TSC2 genes, leading to the overactivation of the mammalian target of rapamycin (mTOR) signalling pathway, which controls several cell functions, including cell growth, proliferation, and survival. The establishment of a connection between TSC and mTOR led to the clinical use of drugs known as mTOR inhibitors (like rapamycin, also known as sirolimus and everolimus), which are becoming an increasingly interesting tool in the management of TSC-associated features, such as subependymal giant cell astrocytomas, renal angiomyolipomas, and also epilepsy. However, the intrinsic characteristics of these drugs and their systemic effects in such a heterogeneous condition pose many challenges in clinical practice, so that some questions remain unanswered. This article provides an overview of the pharmacological aspects of mTOR inhibitors about the clinical trials leading to their approval in TSC-related conditions and exposes current challenges and future directions associated with this promising therapeutic line.

The protective effects of resveratrol, H2S and thermotherapy on the cell apoptosis induced by CdTe quantum dots

Quantum dots (QDs) could be used in the field of biology and medicine as excellent nano-scale fluorescent probes due to their unique optical properties, but the adverse effects of QDs are always the obstruction for its usage in living organisms. In this study, we observed that CdTe QDs exposure decreased the cell viability while increased the apoptosis rates in the L929 cells. Apart from QD-induced oxidative stress indicated by excessive ROS generation, three signal transductions, including Akt, p38 and JNK, played important roles on the regulation of cell apoptosis by CdTe QDs exposure as well. In order to reduce the toxicity of CdTe QDs, we explored the protective effects of three treatments, i.e. resveratrol, H₂S and thermotherapy at 43°C, against the cell apoptosis elicited by CdTe QDs. The results showed that resveratrol, H₂S and thermotherapy at 43°C were capable of attenuating cell apoptosis and intercellular ROS production through inhibiting signal pathways of Akt, p38 and JNK, respectively. As there is only limited number of exogenous treatments reported to diminish the toxicity of QDs, our findings will provide a novel insight for researchers who try to reduce or even eliminate the adverse health effects of QDs.

Tuberous sclerosis complex: From molecular biology to novel therapeutic approaches

Tuberous sclerosis complex (TSC) is a rare multi-system disorder, primary manifestations of which are benign tumors and lesions in various organs of the body, including the brain. TSC patients often suffer from epilepsy, mental retardation, and autism spectrum disorder (ASD). Therefore, TSC serves as a model of epilepsy, ASD, and tumorigenesis. TSC is caused by the lack of functional Tsc1-Tsc2 complex, which serves as a major cellular inhibitor of mammalian Target of Rapamycin Complex 1 (mTORC1). mTORC1 is a kinase controlling most of anabolic processes in eukaryotic cells. Consequently, mTORC1 inhibitors, such as rapamycin, serve as experimental or already approved drugs for several TSC symptoms. However, rapalogs, although quite effective, need to be administered chronically and likely for a lifetime, since therapy discontinuation results in tumor regrowth and epilepsy recurrence. Recent studies revealed that metabolism and excitability (in the case of neurons) of cells lacking Tsc1-Tsc2 complex are changed, and these features may potentially be used to treat some of TSC symptoms. In this review, we first provide basic facts about TSC and its molecular background, to next discuss the newest findings in TSC cell biology that can be used to improve existing therapies of TSC and other diseases linked to mTORC1 hyperactivation. © 2016 IUBMB Life, 68(12):955-962, 2016.

Estrogen induces RAD51C expression and localization to sites of DNA damage

Homologous recombination (HR) is a conserved process that maintains genome stability and cell survival by repairing DNA double-strand breaks (DSBs). The RAD51-related family of proteins is involved in repair of DSBs; consequently, deregulation of RAD51 causes chromosomal rearrangements and stimulates tumorigenesis. RAD51C has been identified as a potential tumor suppressor and a breast and ovarian cancer susceptibility gene. Recent studies have also implicated estrogen as a DNA-damaging agent that causes DSBs. We found that in ERα-positive breast cancer cells, estrogen transcriptionally regulates RAD51C expression in ERα-dependent mechanism. Moreover, estrogen induces RAD51C assembly into nuclear foci at DSBs, which is a precursor to RAD51 complex recruitment to the nucleus. Additionally, disruption of ERα signaling by either anti-estrogens or siRNA prevented estrogen induced upregulation of RAD51C. We have also found an association of a worse clinical outcome between RAD51C expression and ERα status of tumors. These findings provide insight into the mechanism of genomic instability in ERα-positive breast cancer and suggest that individuals with mutations in RAD51C that are exposed to estrogen would be more susceptible to accumulation of DNA damage, leading to cancer progression.

Neuroprotective effects of resveratrol against traumatic brain injury in rats: Involvement of synaptic proteins and neuronal autophagy

Traumatic brain injury (TBI) involves primary and secondary injury cascades that underlie delayed neuronal dysfunction and death, leading to long‑term cognitive deficits, and effective therapeutic strategies targeting neuronal death remain elusive. The present study aimed to determine whether the administration of resveratrol (100 mg/kg) was able to significantly enhance functional recovery in a rat model of TBI and whether resveratrol treatment was able to upregulate synaptic protein expression and suppress post‑TBI neuronal autophagy. The results demonstrated that daily treatment with resveratrol attenuated TBI‑induced brain edema and improved spatial cognitive function and neurological impairment in rats. The expression of synaptic proteins was downregulated following TBI and this phenomenon was partly reversed by treatment with resveratrol. In addition, resveratrol was observed to significantly reduce the levels of the autophagic marker proteins, microtubule‑associated protein light chain 3‑II and Beclin1, in the hippocampus compared with the TBI group. Therefore, these results suggest that resveratrol may represent a novel therapeutic strategy for TBI, and that this protection may be associated with the upregulation of synaptophysin, postsynaptic density protein 95 and the suppression of neuronal autophagy.

ERRα Is a Marker of Tamoxifen Response and Survival in Triple-Negative Breast Cancer

PURPOSE

Estrogen-related receptor alpha (ERRα) signaling has recently been implicated in breast cancer. We investigated the clinical value of ERRα in randomized cohorts of tamoxifen-treated and adjuvant-untreated patients.

EXPERIMENTAL DESIGN

Cox proportional hazards regression was used to evaluate the significance of associations between ERRα gene expression levels and patient DMFS in a previously published microarray dataset representing 2,000 breast tumor cases derived from multiple medical centers worldwide. The 912 tumors used for immunostaining were from a tamoxifen-randomized primary breast cancer trial conducted in Stockholm, Sweden, during 1976-1990. Mouse model was used to study the effect of tamoxifen treatment on lung colonization of MDA-MB-231 control cells and MDA-MB-231 cells with stable knockdown of ERRα. The phenotypic effects associated with ERRα modulation were studied using immunoblotting analyses and wound-healing assay.

RESULTS

We found that in ER-negative and triple-negative breast cancer (TNBC) adjuvant-untreated patients, ERRα expression indicated worse prognosis and correlated with poor outcome predictors. However, in tamoxifen-treated patients, an improved outcome was observed with high ERRα gene and protein expression. Reduced ERRα expression was oncogenic in the presence of tamoxifen, measured by in vitro proliferation and migration assays and in vivo metastasis studies.

CONCLUSIONS

Taken together, these data show that ERRα expression predicts response to tamoxifen treatment, and ERRα could be a biomarker of tamoxifen sensitivity and a prognostic factor in TNBC.

Resveratrol attenuates neuronal autophagy and inflammatory injury by inhibiting the TLR4/NF-κB signaling pathway in experimental traumatic brain injury

Previous research has demonstrated that traumatic brain injury (TBI) activates autophagy and a neuroinflammatory cascade that contributes to substantial neuronal damage and behavioral impairment, and Toll-like receptor 4 (TLR4) is an important mediator of this cascade. In the present study, we investigated the hypothesis that resveratrol (RV), a natural polyphenolic compound with potent multifaceted properties, alleviates brain damage mediated by TLR4 following TBI. Adult male Sprague Dawley rats, subjected to controlled cortical impact (CCI) injury, were intraperitoneally injected with RV (100 mg/kg, daily for 3 days) after the onset of TBI. The results demonstrated that RV significantly reduced brain edema, motor deficit, neuronal loss and improved spatial cognitive function. Double immunolabeling demonstrated that RV decreased microtubule-associated protein 1 light chain 3 (LC3), TLR4‑positive cells co-labeled with the hippocampal neurons, and RV also significantly reduced the number of TLR4‑positive neuron‑specific nuclear protein (NeuN) cells following TBI. Western blot analysis revealed that RV significantly reduced the protein expression of the autophagy marker proteins, LC3II and Beclin1, in the hippocampus compared with that in the TBI group. Furthermore, the levels of TLR4 and its known downstream signaling molecules, nuclear factor-κB (NF-κB), and the inflammatory cytokines, interleukin (IL)-1β and tumor necrosis factor (TNF)-α were also decreased after RV treatment. Our results suggest that RV reduces neuronal autophagy and inflammatory reactions in a rat model of TBI. Thus, we suggest that the neuroprotective effect of RV is associated with the TLR4/NF-κB signaling pathway.

Effects of combining rapamycin and resveratrol on apoptosis and growth of TSC2-deficient xenograft tumors

Lymphangioleiomyomatosis (LAM) is a rare neoplastic metastatic disease affecting women of childbearing age. LAM is caused by hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) as a consequence of tuberous sclerosis complex (TSC) 1/2 inactivation. Clinically, LAM results in cystic lung destruction. mTORC1 inhibition using rapamycin analogs (rapalogs) is partially effective in reducing disease progression and improving lung function. However, cessation of treatment results in continued progression of the disease. In the present study, we investigated the effectiveness of the combination of rapamycin treatment with resveratrol, an autophagy inhibitor, in the TSC2-null xenograft tumor model. We determined that this combination inhibits phosphatidylinositol-4,5-bisphosphate 3-kinase PI3K/Akt/mTORC1 signaling and activates apoptosis. Therefore, the combination of rapamycin and resveratrol may be an effective clinical strategy for treatment of LAM and other diseases with mTORC1 hyperactivation.

Lymphangioleiomyomatosis: Current understanding and potential treatments

Lymphangioleiomyomatosis (LAM) is a rare neoplastic disease affecting predominantly young women. Clinical symptoms of this progressive disease include dyspnoea, cough, recurrent pneumothorax, hemoptysis and chylothorax. LAM is generally aggressive in nature and ultimately results in respiratory failure. Important hallmark features of this metastatic disease include the formation of lesions of abnormal smooth muscle cells, cystic destruction of the lung tissue and lymphangiogenesis affecting the lungs, abdomen and lymphatics. Research over the last 10-15 years has significantly enhanced our understanding of the molecular and cellular processes associated with LAM. These processes include mutational inactivation of the tuberous sclerosis complex genes, TSC1 and TSC2, activation of the mammalian target of rapamycin (mTOR) pathway, enhanced cell proliferation and migration, lymphangiogenesis, metastatic spread through the blood and lymphatic circulations, sex steroid sensitivity and dysregulated autophagy. Despite this increased knowledge there is currently no cure for LAM and treatment options remain limited. Whilst the mTOR inhibitor rapamycin has shown some benefit in patients with LAM, with stabilisation of lung function and improved quality of life, cessation of treatment results in recurrence of the disease progression. This highlights the urgent need to identify novel targets and new treatment regimens. The focus of this review is to summarise our current understanding of the cellular and molecular processes associated with LAM and highlight emerging treatments.

The combination of rapamycin and resveratrol blocks autophagy and induces apoptosis in breast cancer cells

Hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) is a frequent event in breast cancer and current efforts are aimed at targeting the mTORC1 signaling pathway in combination with other targeted therapies. However, patients often develop drug resistance in part due to activation of the oncogenic Akt signaling and upregulation of autophagy, which protects cancer cells from apoptosis. In the present study we investigated the effects of combination therapy of rapamycin (an allosteric mTORC1 inhibitor) together with resveratrol (a phytoestrogen that inhibits autophagy). Our results show that combination of these drugs maintains inhibition of mTORC1 signaling, while preventing upregulation of Akt activation and autophagy, causing apoptosis. Additionally, this combination was effective in estrogen receptor positive and negative breast cancer cells, underscoring its versatility.

Resveratrol as a novel treatment for diseases with mTOR pathway hyperactivation

The mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway is hyperactivated in a variety of cancers and tumor syndromes. Therefore, mTORC1 inhibitors are being actively investigated for treatment of neoplasms. The concern with the monotherapy use of mTORC1 inhibitors, such as rapamycin, is that they cause upregulation of autophagy, a cell survival mechanism, and suppress the negative feedback loop to the oncogene Akt. In turn, Akt promotes cell survival, causing the therapy to be partially effective, but relapse occurs upon cessation of treatment. In this review, we describe the current literature on resveratrol as well as our work, which uses rapamycin in combination with resveratrol. We found that this combination treatment efficiently blocked upregulation of autophagy and restored inhibition of Akt in different cancer and tumor models. Interestingly, the combination of rapamycin and resveratrol selectively promoted apoptosis of cells with mTOR pathway hyperactivation. Moreover, this combination prevented tumor growth and lung metastasis when tested in mouse models. Finally, mass spectrometry-based identification of cellular targets of resveratrol provided mechanistic insight into the mode of action of resveratrol. The addition of resveratrol to rapamycin treatment may be a promising option for selective and targeted therapy for diseases with mTORC1 hyperactivation.

Resveratrol inhibits NLRP3 inflammasome activation by preserving mitochondrial integrity and augmenting autophagy

The NLRP3 inflammasome is a caspase-1-containing multi-protein complex that controls the release of IL-1β and plays important roles in the development of inflammatory disease. Here, we report that resveratrol, a polyphenolic compound naturally produced by plants, inhibits NLRP3 inflammasome-derived IL-1β secretion and pyroptosis in macrophages. Resveratrol inhibits the activation step of the NLRP3 inflammasome by suppressing mitochondrial damage. Resveratrol also induces autophagy by activating p38, and macrophages treated with an autophagy inhibitor are resistant to the suppressive effects of resveratrol. In addition, resveratrol administration mitigates glomerular proliferation, glomerular sclerosis, and glomerular inflammation in a mouse model of progressive IgA nephropathy. These findings were associated with decreased renal mononuclear leukocyte infiltration, reduced renal superoxide anion levels, and inhibited renal NLRP3 inflammasome activation. Our data indicate that resveratrol suppresses NLRP3 inflammasome activation by preserving mitochondrial integrity and by augmenting autophagy.

Management of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a multisystem disease affecting almost exclusively women, is characterized by cystic lung destruction and presents with dyspnea, recurrent pneumothoraxes, chylous effusions, lymphangioleiomyomas, and angiomyolipomas. It is caused by the proliferation of a cancer-like LAM cell that possesses a mutation in either the tuberous sclerosis complex (TSC)1 or TSC2 genes. This article reviews current therapies and new potential treatments that are currently undergoing investigation. The major development in the treatment of LAM is the discovery of two mammalian target of rapamycin (mTOR) inhibitors, sirolimus and everolimus, as effective drugs. However, inhibition of mTOR increases autophagy, which may lead to enhanced LAM cell survival. Use of autophagy inhibitors, for example, hydroxychloroquine, in combination with sirolimus is now the subject of an ongoing drug trial (SAIL trial). Another consequence of mTOR inhibition by sirolimus is an increase in Rho activity, resulting in reduced programmed cell death. From these data, the concept evolved that a combination of sirolimus with disruption of Rho activity with statins (e.g. simvastatin) may increase TSC-null cell death and reduce LAM cell survival. A combined trial of sirolimus with simvastatin is under investigation (SOS trial). Since LAM occurs primarily in women and TSC-null cell survival and tumor growth is promoted by estrogens, the inhibition of aromatase to block estrogen synthesis is currently undergoing study (TRAIL trial). Other targets, for example, estrogen receptors, mitogen-activated protein kinase inhibitors, vascular endothelial growth factor-D signaling pathway, and Src kinase, are also being studied in experimental model systems. As in the case of cancer, combination therapy may become the treatment of choice for LAM.

Inhibition of mTOR reduce Stat3 and PAI related angiogenesis in salivary gland adenoid cystic carcinoma

Angiogenesis is a complex biological process, which is involved in tumorigenesis and progression. However, the molecular mechanism of underlying angiogenesis remains largely unknown. In this study, we accessed the expression of proteins related angiogenesis by immunohistochemical staining of human tissue microarray which contains 72 adenoid cystic carcinoma (AdCC), 12 pleomorphic adenoma (PMA) and 18 normal salivary gland (NSG) using digital pathological scanner and scoring system. We found that the expression of p-S6(S235/236) (a downstream molecule of mTOR), p-Stat3(T705), PAI, EGFR, and HIF-1α was significantly increased in AdCC as compared with PMA and (or) NSG (p < 0.05). While, the expression of these proteins was not associated with pathological type of human AdCC (p > 0.05). Correlation analysis of these proteins revealed that p-S6(S235/236) up-regulates the expression of EGFR/p-Stat3(T705) (p < 0.05) and HIF-1α/PAI (p < 0.05). Moreover, the activation of p-S6(S235/236), EGFR/p-Stat3(T705) and HIF-1α/PAI associated with angiogenesis (CD34) and proliferation (Ki-67). In vitro, Rapamycin suppressed the expression of p-S6(S235/236), EGFR, p-Stat3(T705), HIF-1α and PAI. Further more, target inhibition of mTOR by rapamycin effectively reduced tumor growth of SACC-83 cells line nude mice xenograft and decreased the expression of p-S6(S235/236), EGFR/p-Stat3(T705) and HIF-1α/PAI. Taken together, these data revealed that mTOR signaling pathway regulates tumor angiogenesis by EGFR/p-Stat3(T705) and HIF-1α/PAI. Inhibition of mTOR by rapamycin could effectively reduced tumor growth. It is likely that mTOR inhibitors may be a potential candidate for treatment of AdCC.

Phosphoproteomics reveals resveratrol-dependent inhibition of Akt/mTORC1/S6K1 signaling

Resveratrol, a plant-derived polyphenol, regulates many cellular processes, including cell proliferation, aging and autophagy. However, the molecular mechanisms of resveratrol action in cells are not completely understood. Intriguingly, resveratrol treatment of cells growing in nutrient-rich conditions induces autophagy, while acute resveratrol treatment of cells in a serum-deprived state inhibits autophagy. In this study, we performed a phosphoproteomic analysis after applying resveratrol to serum-starved cells with the goal of identifying the acute signaling events initiated by resveratrol in a serum-deprived state. We determined that resveratrol in serum-starved conditions reduces the phosphorylation of several proteins belonging to the mTORC1 signaling pathway, most significantly, PRAS40 at T246 and S183. Under these same conditions, we also found that resveratrol altered the phosphorylation of several proteins involved in various biological processes, most notably transcriptional modulators, represented by p53, FOXA1, and AATF. Together these data provide a more comprehensive view of both the spectrum of phosphoproteins upon which resveratrol acts as well as the potential mechanisms by which it inhibits autophagy in serum-deprived cells.

Therapeutic targeting of cellular metabolism in cells with hyperactive mTORC1: a paradigm shift

mTORC1 is an established master regulator of cellular metabolic homeostasis, via multiple mechanisms that include altered glucose and glutamine metabolism, and decreased autophagy. mTORC1 is hyperactive in the human disease tuberous sclerosis complex (TSC), an autosomal dominant disorder caused by germline mutations in the TSC1 or TSC2 gene. In TSC-deficient cells, metabolic wiring is extensively disrupted and rerouted as a consequence of mTORC1 hyperactivation, leading to multiple vulnerabilities, including "addiction" to glutamine, glucose, and autophagy. There is synergy between two rapidly evolving trajectories: elucidating the metabolic vulnerabilities of TSC-associated tumor cells, and the development of therapeutic agents that selectively target cancer-associated metabolic defects. The current review focuses on recent work supporting the targeting of cellular metabolic dysregulation for the treatment of tumors in TSC, with relevance to the many other human neoplasms with mTORC1 hyperactivation. These data expose a fundamental paradox in the therapeutic targeting of tumor cells with hyperactive mTORC1: inhibition of mTORC1 may not represent the optimal therapeutic strategy. Inhibiting mTORC1 "fixes" the metabolic vulnerabilities, results in a cytostatic response, and closes the door to metabolic targeting. In contrast, leaving mTORC1 active allows the metabolic vulnerabilities to be targeted with the potential for a cytocidal cellular response. The insights provided here suggest that therapeutic strategies for TSC and other tumors with activation of mTORC1 are at the verge of a major paradigm shift, in which optimal clinical responses will be accomplished by targeting mTORC1-associated metabolic vulnerabilities without inhibiting mTORC1 itself.

Resveratrol inhibits breast cancer stem-like cells and induces autophagy via suppressing Wnt/β-catenin signaling pathway

Resveratrol, a natural polyphenolic compound, is abundantly found in plant foods and has been extensively studied for its anti-cancer properties. Given the important role of CSCs (Cancer Stem Cells) in breast tumorigenesis and progression, it is worth investigating the effects of resveratrol on CSCs. The article is an attempt to investigate the effects of resveratrol on breast CSCs. Resveratrol significantly inhibits the proliferation of BCSCs (breast cancer stem-like cells) isolated from MCF-7 and SUM159, and decreased the percentage of BCSCs population, consequently reduced the size and number of mammospheres in non-adherent spherical clusters. Accordingly, the injection of resveratrol (100 mg/kg/d) in NOD/SCID (nonobese diabetic/severe combined immunodeficient) mice effectively inhibited the growth of xenograft tumors and reduced BCSC population in tumor cells. After the reimplantation of primary tumor cells into the secondary mice for 30 d, all 6 control inoculations produced tumors, while tumor cells derived from resveratrol-treated mice only caused 1 tumor of 6 inoculations. Further studies by TEM (Transmission electron microscopy) analysis, GFP-LC3-II puncta formation assay and western blot for LC3-II, Beclin1 and Atg 7, showed that resveratrol induces autophagy in BCSCs. Moreover, resveratrol suppresses Wnt/β-catenin signaling pathway in BCSCs; over-expression of β-catenin by transfecting the plasmid markedly reduced resveratrol-induced cytotoxicity and autophagy in BCSCs. Our findings indicated that resveratrol inhibits BCSCs and induces autophagy via suppressing Wnt/β-catenin signaling pathway.

Resveratrol protects vascular smooth muscle cells against high glucose-induced oxidative stress and cell proliferation in vitro

Background

Resveratrol exhibits beneficial effects against numerous degenerative diseases at different stages of pathogenesis. This study investigated potential mechanisms and resveratrol effects on high glucose (HG)-induced oxidative stress (30 mM d-glucose, 30 min) and cell proliferation (30 mM d-glucose, 24 h) in vascular smooth muscle cells (VSMCs).

Material/Methods

Intracellular reactive oxygen species (ROS) generation was detected by 2′,7′-dichlorofluorescein diacetate (DCFH-DA). Total antioxidant capacity (TAC), malonyldialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) were measured to evaluate oxidative stress. VSMC proliferation was measured by CCK-8 assays and through propidium iodide-based cell cycle analysis. Expression of NAD(P)H oxidase, proliferation proteins, and cell signalling were assessed by immunoblot analysis.

Results

Co-treatment of primary cultures of VSMCs with 1–100 μM resveratrol decreased HG-induced ROS overproduction (P<0.05). Resveratrol also abolished HG-induced phosphorylation of oxidase subunit p47 phox and reduced HG-induced cyclin D1, cyclin E, and PCNA expression in a concentration-dependent manner. Furthermore, resveratrol (10 μM) attenuated HG-induced phosphorylation of Akt, p38 mitogen-activated protein kinase (MAPK), ERK 1/2, and JNK1/2 without affecting total levels. HG stimulation enhanced downstream IκB-α phosphorylation and NF-κB activity, and resveratrol repressed these effects.

Conclusions

Resveratrol inhibits HG-induced oxidative stress and VSMC proliferation by suppressing ROS generation, NADPH oxidase, Akt phosphorylation, p38 MAPK/JNK/ERK phosphorylation, and IκB-α and NF-κB activities.

Resveratrol protects astrocytes against traumatic brain injury through inhibiting apoptotic and autophagic cell death

Traumatic brain injury (TBI) is often caused by accidents that damage the brain. TBI can induce glutamate excitotoxicity and lead to neuronal and glial cell death. In this study, we investigated the mechanism of cell death during the secondary damage caused by TBI in vivo and in vitro, as well as the protective effect of resveratrol (RV). Here we report that glycogen synthase kinase-3β (GSK-3β) activation and microtubule-associated protein light chain 3 processing were induced in rat brains exposed to TBI. In the in vitro TBI model, apoptotic and autophagic cell death were induced through glutamate-mediated GSK-3β activation in normal CTX TNA2 astrocytes. The GSK-3β inhibitor SB216763 or transfection of GSK-3β small-interfering RNA increases cell survival. By contrast, overexpression of GSK-3β enhanced glutamate excitotoxicity. Administration of RV reduced cell death in CTX TNA2 astrocytes by suppressing reactive oxygen species (ROS)-mediated GSK-3β activation, the mechanism by which RV also exerted protective effects in vivo. Mitochondrial damages, including the opening of mitochondrial permeability transition pore (MPTP) and mitochondrial depolarization, were induced by glutamate through the ROS/GSK-3β pathway. Moreover, cyclosporine A, an MPTP inhibitor, suppressed mitochondrial damage and the percentages of cells undergoing autophagy and apoptosis and thereby increased cell survival. Taken together, our results demonstrated that cell death occurring after TBI is induced through the ROS/GSK-3β/mitochondria signaling pathway and that administration of RV can increase cell survival by suppressing GSK-3β-mediated autophagy and apoptosis. Therefore, the results indicated that resveratrol may serve as a potential therapeutic agent in the treatment of TBI.