Combination of melatonin and rapamycin for head and neck cancer therapy: Suppression of AKT/mTOR pathway activation, and activation of mitophagy and apoptosis via mitochondrial function regulation

Melatonin promotes neuroblastoma cell differentiation by activating hyaluronan synthase 3-induced mitophagy

Neuroblastoma is the second most common pediatric malignancy and has a high rate of spontaneous remission. Uncovering the mechanisms underlying neuroblastoma cell differentiation is critical for therapeutic purposes. A neuroblastoma cell line (N2a) treated with either serum withdrawal (<2.5%) or melatonin (>0.1 nmol/L) for 24 hours was used as a cell differentiation research model. Interestingly, the hyaluronan synthase 3 (HAS3) protein was induced in differentiated N2a cells. N2a-allografted nude mice received an intraperitoneal injection of melatonin (40 or 80 mg/kg/day for 3 weeks). The mean tumor volume in mice treated with 80 mg/kg melatonin was smaller than that in PBS-treated mice (1416.3 and 3041.3 mm³ , respectively, difference = 1625 mm³ , *P = 0.0003, n = 7 per group). Compared with the vector control group, N2a cells with forced HAS3 overexpression showed significantly increased neuron length (*P = 0.00082) and neurite outgrowth (*P = 0.00059). Intracellular changes in autophagy, including distorted mitochondria with abnormal circular inner membranes, were detected by transmission electron microscopy (TEM). Our study demonstrated that HAS3-mediated signaling activated by physiological concentrations of melatonin (>0.1 nmol/L) triggered significant N2a cell differentiation. These results provide molecular data with potential clinical relevance for therapeutic drug development.

Caveolin-1 knockdown increases the therapeutic sensitivity of lung cancer to cisplatin-induced apoptosis by repressing Parkin-related mitophagy and activating the ROCK1 pathway

Chemotherapy is the first-line treatment option for patients with lung cancer. However, therapeutic resistance occurs through an incompletely understood mechanism. Our research wants to investigate the influence of Caveolin-1 (Cav-1) on the therapeutic sensitivity of lung cancer in vitro. Results in this study demonstrated that Cav-1 levels were markedly inhibited in A549 lung cancer cells after exposure to cisplatin. Knockdown of caveolin further enhanced cisplatin-triggered cancer death in A549 cells. The functional investigation demonstrated that Cav-1 inhibition amplified the mitochondrial stress signaling induced by cisplatin, as evidenced by the mitochondrial reactive oxygen species burst, cellular metabolic disruption, mitochondrial membrane potential reduction, and mitochondrial caspase-9-related apoptosis activation. At the molecular level, cav-1 augmented cisplatin-mediated mitochondrial damage by inhibiting Parkin-related mitochondrial autophagy. Mitophagy activation effectively attenuated the promotive impact of Cav-1 knockdown on mitochondrial damage and cell death. Furthermore, our data indicated that Cav-1 affected Parkin-related mitophagy by activating the Rho-associated coiled-coil kinase 1 (ROCK1) pathway; inhibition of the ROCK1 axis prevented cav-1 knockdown-mediated cell death and mitochondrial damage. Taken together, our results provide ample data illuminate the necessary action exerted by Cav-1 on affecting cisplatin-related therapeutic resistance. Silencing of Cav-1 inhibited Parkin-related mitophagy, thus amplifying cisplatin-mediated mitochondrial apoptotic signaling. This finding identifies the Cav-1/ROCK1/Parkin/mitophagy axis as a potential target to overcome cisplatin-related resistance in lung cancer cells.

Matrine promotes apoptosis in SW480 colorectal cancer cells via elevating MIEF1-related mitochondrial division in a manner dependent on LATS2-Hippo pathway

Matrine, an alkaloid compound isolated from Sophora flavescens Ait, has been shown to exert cancer-killing actions in a variety of tumors; however, its anticancer mechanism in colorectal cancer (CRC) is not clear. The goal of our study was to characterize the anticancer effects and molecular mechanisms of matrine in SW480 CRC cells in vitro. Matrine treatment reduced mitochondrial metabolic function and ATP levels, repressed mitochondrial membrane potential, evoked mitochondrial reactive oxygen species accumulation, and promoted cyt-c-related mitochondrial apoptosis activation. In addition, we found that matrine treatment activated mitochondrial fission through upregulating mitochondrial elongation factor 1 (MIEF1); silencing of MIEF1 prevented matrine-mediated mitochondrial damage and reversed the decrease in SW480 cell viability. Moreover, matrine treatment affected MIEF1 expression via the large tumor suppressor-2 (LATS2)-Hippo axis, and LATS2 deficiency suppressed the anticancer actions exerted by matrine on SW480 cancer cells. In summary, we show for the first time that matrine inhibits SW480 cell survival by activating MIEF1-related mitochondrial division via the LATS2-Hippo pathway. These findings explain the anticancer mechanisms of matrine in CRC and also identify the LATS2-MIEF1 signaling pathway as an effective target for the treatment of CRC.

Mst1 overexpression combined with Yap knockdown augments thyroid carcinoma apoptosis via promoting MIEF1-related mitochondrial fission and activating the JNK pathway

Background

Cancer cell viability is strongly modulated by the Hippo pathway, which includes mammalian STE20-like protein kinase 1 (Mst1) and yes-associated protein (Yap). Although the roles of Mst1 and Yap in thyroid carcinoma cell death have been fully addressed, no study has determined whether differential modification of Mst1 and Yap could further suppress thyroid carcinoma progression. The aim of our study was to explore the antiapoptotic effects exerted by combined Mst1 overexpression and Yap knockdown in thyroid carcinoma MDA-T32 cells in vitro.

Methods

Mst1 adenovirus and Yap shRNA were transfected into MDA-T32 cells to overexpress Mst1 and inhibit Yap, respectively. Cell viability and death were determined via an MTT assay, a TUNEL assay and western blotting. Mitochondrial function, mitochondrial fission and pathway studies were performed via western blotting and immunofluorescence.

Results

The results of our study showed that combined Mst1 overexpression and Yap knockdown further augmented MDA-T32 cell death by mediating mitochondrial damage. In addition, cancer cell migration and proliferation were suppressed by combined Mst1 overexpression and Yap knockdown. At the molecular level, mitochondrial membrane potential, ATP production, respiratory function, and caspase-9-related apoptosis were activated by combined Mst1 overexpression and Yap knockdown. Further, we found that fatal mitochondrial fission was augmented by combined Mst1 overexpression and Yap knockdown in a manner dependent on the JNK-MIEF1 pathway. Inhibition of JNK-MIEF1 pathway activity abolished the proapoptotic effects exerted by Mst1/Yap on MDA-T32 cells.

Conclusions

Taken together, our data suggest that Mst1 activation and Yap inhibition coordinate to augment thyroid cancer cell death by controlling the JNK-MIEF1-mitochondria pathway, suggesting that differential regulation of the core Hippo pathway components is potentially a novel therapeutic tool for the treatment of thyroid cancer.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0860-8) contains supplementary material, which is available to authorized users.

Reduced delivery of epididymal adipocyte-derived exosomal resistin is essential for melatonin ameliorating hepatic steatosis in mice

Adipocyte-derived exosomes (Exos) serve as bioinformation-containing messengers in cell-to-cell communications, and numerous reports demonstrate that resistin, an adipokine, is strongly associated with hepatic steatosis and other fatty liver diseases, suggesting that adipose dysfunction-generated altered pattern of exosomal cytokines may contribute to shaping the physiological activities in liver. Admittedly, melatonin-mediated positive effects on various tissues/organs have been respectively reported, but regulatory mechanisms of melatonin on the crosstalk between adipose tissue and liver have been investigated rarely. Overall, we hypothesize that the crosstalk originating from adipose tissue may be another worthy regulatory pathway for melatonin ameliorating of hepatic steatosis. Here, we first found the amount of adipocyte-derived exosomal resistin to be significantly decreased by melatonin supplementation. Compared to mice with Exos_HFD or Exos_resistin treatment, Exos_MT remarkably ameliorated hepatic steatosis. Further test demonstrated that resistin was a pivotal cytokine which repressed phosphorylation of 5' adenosine monophosphate-activated protein kinase α (pAMPKα Thr¹⁷² ) to trigger endoplasmic reticulum (ER) stress, resulting in hepatic steatosis, whereas Exos_MT reversed these risks in hepatocytes. In adipocytes, we identified melatonin to reduce the production of resistin through the brain and muscle arnt-like protein 1 (Bmal1) transcriptional inhibition. Notably, we also confirmed that melatonin enhanced N⁶ -Methyladenosine (m⁶ A) RNA demethylation to degrade resistin mRNA in adipocytes. Overall, melatonin decreases traffic volume of adipocyte-generated exosomal resistin from adipocytes to hepatocytes, which further alleviates ER stress-induced hepatic steatosis. Our findings illustrate a novel melatonin-mediated regulatory pathway from adipocytes to hepatocytes, indicating that adipocyte-derived exosome is a new potential target for treating obesity and related hepatorenal syndrome.

Inhibition of PI3K/mTOR increased the sensitivity of hepatocellular carcinoma cells to cisplatin via interference with mitochondrial-lysosomal crosstalk

OBJECTIVES

The genotoxicity of cisplatin towards nuclear DNA is not sufficient to explain the cisplatin resistance of hepatocellular carcinoma (HCC) cells; cisplatin interacts with many organelles, which can influence the sensitivity. Here, we explored the role of mitochondrial-lysosomal crosstalk in the cisplatin resistance of HCC cells.

MATERIALS AND METHODS

Huh7 and HepG2 cells were subjected to different treatments. Flow cytometry was conducted to detect mitochondrial reactive oxygen species, mitochondrial mass, lysosomal function, mitochondrial membrane potential and apoptosis. Western blotting was performed to evaluate protein levels. The oxygen consumption rate was measured to evaluate mitochondrial function.

RESULTS

Cisplatin activated mitophagy and lysosomal biogenesis, resulting in crosstalk between mitochondria and lysosomes and cisplatin resistance in HCC cells. Furthermore, a combination of cisplatin with the phosphatidylinositol-3-kinase/mammalian target of rapamycin (PI3K/mTOR) inhibitor PKI-402 induced lysosomal membrane permeabilization. This effect changed the role of the lysosome from a protective one to that of a cell death promoter, completely destroying the mitochondrial-lysosomal crosstalk and significantly enhancing the sensitivity of HCC cells to cisplatin.

CONCLUSIONS

This is the first evidence of the importance of mitochondrial-lysosomal crosstalk in the cisplatin resistance of HCC cells and of the destruction of this crosstalk by a PI3K/mTOR inhibitor to increase the sensitivity of HCC cells to cisplatin. This mechanism could be developed as a novel target for treatment of HCC in the future.

Overexpression of macrophage stimulating 1 enhances the anti-tumor effects of IL-24 in esophageal cancer via inhibiting ERK-Mfn2 signaling-dependent mitophagy

Although cytokine-based therapy is a promising tool to control the progression of esophageal cancer, low therapeutic responses largely compromise treatment efficacy through unidentified mechanisms. The goal of our study was to explore the roles of macrophage stimulating 1 (Mst1) and mitophagy in enhancing IL-24-based cytokine therapy in esophageal cancer. Our data demonstrated that IL-24 application promoted cancer death by inducing mitochondrial stress, as manifested by mitochondrial ROS overproduction, mitochondrial potential dissipation, cellular ATP deprivation and mitochondrial death activation. Overexpression of Mst1 enhanced IL-24-mediated mitochondrial damage and further augmented IL-24-induced death in esophageal cancer. Molecular investigations illustrated that the IL-24-activated mitochondrial response is accompanied by activation of mitophagy, a protective mechanism to attenuate mitochondrial damage. However, Mst1 overexpression inhibited mitophagy activity, which was achieved by inactivating the ERK-Mfn2 signaling pathway. The re-activation of mitophagy abolished the cancer-killing effects of Mst1 overexpression on esophageal cancer. Altogether, our data demonstrate that IL-24-related therapeutic resistance is associated with mitophagy activation. Mst1 overexpression inhibits mitophagy activity via suppressing the ERK-Mfn2 pathway, ultimately augmenting IL-24-inducd esophageal cancer death via enhanced mitochondrial stress.

LATS2 overexpression attenuates the therapeutic resistance of liver cancer HepG2 cells to sorafenib-mediated death via inhibiting the AMPK-Mfn2 signaling pathway

Background

Effective therapy for hepatocellular carcinoma (HCC) is currently an imperative issue, and sorafenib is a first-line drug for the treatment of HCC. However, the clinical benefit of sorafenib is often impaired by drug resistance. Accordingly, the present study was conducted to investigate the molecular mechanisms involving sorafenib resistance, with a focus on large tumor suppressor 2 (LATS2) and mitophagy.

Methods

HepG2 liver cancer cells were treated with sorafenib and infected with adenovirus-loaded LATS2 (Ad-LATS2). Cell death, proliferation and migration were measured via western blotting analysis, immunofluorescence and qPCR. Mitochondrial function and mitophagy were determined via western blotting and immunofluorescence.

Results

Our data indicated that LATS2 expression was repressed by sorafenib treatment, and overexpression of LATS2 could further enhance sorafenib-mediated apoptosis in HepG2 liver cancer cells. At the molecular level, mitochondrial stress was triggered by sorafenib treatment, as evidenced by decreased mitochondrial membrane potential, increased mitochondrial ROS production, more cyc-c release into the nucleus, and elevated mitochondrial pro-apoptotic proteins. However, in response to mitochondrial damage, mitophagy was activated by sorafenib treatment, whereas LATS2 overexpression effectively inhibited mitophagy activity and thus augmented sorafenib-mediated mitochondrial stress. Subsequently, we also demonstrated that the AMPK–MFN2 signaling pathway was involved in mitophagy regulation after exposure to sorafenib treatment and/or LATS2 overexpression. Inhibition of the AMPK pathway interrupted mitophagy and thus enhanced the antitumor property of sorafenib, similar to the results obtained via overexpression of LATS2.

Conclusions

Altogether, our findings revealed the importance of the LATS2/AMPK/MFN2/mitophagy axis in understanding sorafenib resistance mechanisms, with a potential application to increase the sensitivity response of sorafenib in the treatment of liver cancer.

Melatonin enhances TNF-α-mediated cervical cancer HeLa cells death via suppressing CaMKII/Parkin/mitophagy axis

Background

Tumor necrosis factor-α (TNF-α) immunotherapy controls the progression of human cervical cancer. Here, we explored the detailed molecular mechanisms played by melatonin in human cervical cancer (HeLa cells) death in the presence of TNF-α injury, with a particular attention to the mitochondrial homeostasis.

Methods

HeLa cells were incubated with TNFα and then cell death was determined via MTT assay, TUNEL staining, caspase ELISA assay and western blotting. Mitochondrial function was detected via analyzing mitochondrial membrane potential using JC-1 staining, mitochondrial oxidative stress using flow cytometry and mitochondrial apoptosis using western blotting.

Results

Our data exhibited that treatment with HeLa cells using melatonin in the presence of TNF-α further triggered cancer cell cellular death. Molecular investigation demonstrated that melatonin enhanced the caspase-9 mitochondrion death, repressed mitochondrial potential, increased ROS production, augmented mPTP opening rate and elevated cyt-c expression in the nucleus. Moreover, melatonin application further suppressed mitochondrial ATP generation via reducing the expression of mitochondrial respiratory complex. Mechanistically, melatonin augmented the response of HeLa cells to TNF-α-mediated cancer death via repressing mitophagy. TNF-α treatment activated mitophagy via elevating Parkin expression and excessive mitophagy blocked mitochondrial apoptosis, ultimately alleviating the lethal action of TNF-α on HeLa cell. However, melatonin supplementation could prevent TNF-α-mediated mitophagy activation via inhibiting Parkin in a CaMKII-dependent manner. Interestingly, reactivation of CaMKII abolished the melatonin-mediated mitophagy arrest and HeLa cell death.

Conclusions

Overall, our data highlight that melatonin enhances TNF-α-induced human cervical cancer HeLa cells mitochondrial apoptosis via inactivating the CaMKII/Parkin/mitophagy axis.

Melatonin Enhances Cisplatin and Radiation Cytotoxicity in Head and Neck Squamous Cell Carcinoma by Stimulating Mitochondrial ROS Generation, Apoptosis, and Autophagy

Head and neck cancer is the sixth leading cancer by incidence worldwide. Unfortunately, drug resistance and relapse are the principal limitations of clinical oncology for many patients, and the failure of conventional treatments is an extremely demoralizing experience. It is therefore crucial to find new therapeutic targets and drugs to enhance the cytotoxic effects of conventional treatments without potentiating or offsetting the adverse effects. Melatonin has oncostatic effects, although the mechanisms involved and doses required remain unclear. The purpose of this study is to determine the precise underlying mitochondrial mechanisms of melatonin, which increase the cytotoxicity of oncological treatments, and also to propose new melatonin treatments in order to alleviate and reverse radio- and chemoresistant processes. We analyzed the effects of melatonin on head and neck squamous cell carcinoma (HNSCC) cell lines (Cal-27 and SCC-9), which were treated with 0.1, 0.5, 1, and 1.5 mM melatonin combined with 8 Gy irradiation or 10 μM cisplatin. Clonogenic and MTT assays, as well as autophagy and apoptosis, involving flow cytometry and western blot, were performed in order to determine the cytotoxic effects of the treatments. Mitochondrial function was evaluated by measuring mitochondrial respiration, mtDNA content (RT-PCR), and mitochondrial mass (NAO). ROS production, antioxidant enzyme activity, and GSH/GSSG levels were analyzed using a fluorometric method. We show that high concentrations of melatonin potentiate the cytotoxic effects of radiotherapy and CDDP in HNSCC, which are associated with increased mitochondrial function in these cells. In HNSCC, melatonin induces intracellular ROS, whose accumulation plays an upstream role in mitochondria-mediated apoptosis and autophagy. Our findings indicate that melatonin, at high concentrations, combined with cisplatin and radiotherapy to improve its effectiveness, is a potential adjuvant agent.

Melatonin: The smart molecule that differentially modulates autophagy in tumor and normal placental cells

Melatonin has protective roles in normal cells and cytotoxic actions in cancer cells, with effects involving autophagy and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) transcription factor pathways. Hypoxia/reoxygenation (H/R) induces oxidative damage and apoptosis. These consequences activate autophagy, which degrades damaged cellular content, as well as activates Nrf2 the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) transcription factor, and thereby the expression of protective genes. Melatonin has protective roles in normal cells and cytotoxic actions in cancer cells, with effects involving autophagy and Nrf2 pathways. The current study shows melatonin to differentially modulate autophagy and Nrf2 pathways in tumor and normal placental cells exposed to H/R. BeWo, a human placental choriocarcinoma cell line, and primary villous cytotrophoblasts isolated from normal term placenta, were maintained in normoxia (8% O₂) for 24 h or exposed to hypoxia (0.5% of O₂ for 4 h) followed by 20 h of normoxia, creating a situation of H/R, in the presence or absence of 1 mM melatonin. Melatonin induced a 7-fold increase in the activation of 5' adenosine monophosphate-activated protein kinase (AMPK)α, an upstream modulator of autophagy, rising to a 16-fold increase in BeWo cells co-exposed to H/R and melatonin, compared to controls. H/R induced autophagosome formation via the increased expression of Beclin-1 (by 94%) and ATG7 (by 97%) in BeWo cells. Moreover, H/R also induced autophagic activity, indicated by the by the 630% increase in P62, and increased Nrf2 by 314% in BeWo cells. In H/R conditions, melatonin reduced autophagic activity by 74% and Nrf2 expression activation by 300%, leading to BeWo cell apoptosis. In contrast, In human primary villous cytotrophoblasts, H/R induced autophagy and Nrf2, which melatonin further potentiated, thereby affording protection against H/R. This study demonstrates that melatonin differentially modulates autophagy and the Nrf2 pathway in normal vs. tumor trophoblast cells, being cytoprotective in normal cells whilst increasing apoptosis in tumoral trophoblast cells.

Therapeutic potential of melatonin related to its role as an autophagy regulator: A review

There are several pathologies, syndromes, and physiological processes in which autophagy is involved. This process of self-digestion that cells trigger as a survival mechanism is complex and tightly regulated, according to the homeostatic conditions of the organ. However, in all cases, its relationship with oxidative stress alterations is evident, following a pathway that suggests endoplasmic reticulum stress and/or mitochondrial changes. There is accumulating evidence of the beneficial role that melatonin has in the regulation and restoration of damaged autophagic processes. In this review, we focus on major physiological changes such as aging and essential pathologies including cancer, neurodegenerative diseases, viral infections and obesity, and document the essential role of melatonin in the regulation of autophagy in each of these different situations.

LATS2 promotes apoptosis in non-small cell lung cancer A549 cells via triggering Mff-dependent mitochondrial fission and activating the JNK signaling pathway

LATS2 is a classical tumor suppressor that affects non-small cell lung cancer proliferation and mobilization. However, its role in lung cancer cell apoptosis is unknown. The aim of our study is to explore whether LATS2 activates mitochondria-related apoptosis in lung cancer cells. In the present study, A549 non-small cell lung cancer cells were transfected with a LATS2 adenovirus to induce LATS2 overexpression. Cell apoptosis was evaluated via the MTT assay, TUNEL staining, western blotting, trypan blue staining and ELISA. Mitochondrial function was measured using an immunofluorescence assay, western blotting and ELISA. The results demonstrated that LATS2 was downregulated in A549 lung cancer cells. Overexpression of LATS2 induced A549 cell apoptosis via activating mitochondrial fission. Subsequently, we confirmed that LATS2 modulated mitochondrial fission via the JNK-Mff signaling pathway. Inhibition of the JNK pathway and/or knockdown of Mff abolished the pro-apoptotic effect of LATS2 on A549 cells. Taken together, our results identified LATS2 as a classical tumor suppressor of lung cancer via triggering mitochondrial fission and activating the JNK-Mff signaling pathway. Our results lay the foundation for detailed study of the molecular mechanisms of LATS2 overexpression and regulation of mitochondrial fission for lung cancer treatment.

Melatonin, a toll-like receptor inhibitor: Current status and future perspectives

Toll-like receptors (TLRs) are crucial activators of inflammatory responses, they are considered immune receptors. TLRs are of fundamental importance in the pathophysiology of disorders related to inflammation including neurodegenerative diseases and cancer. Melatonin is a beneficial agent in the treatment of inflammatory and immune disorders. Melatonin is potent anti-inflammatory hormone that regulates various molecular pathways. Withal, limited studies have evaluated the inhibitory role of melatonin on TLRs. This review summarizes the current knowledge related to the effects of melatonin on TLRs in some common inflammatory and immunity disorders.

Contribution of regulatory T cells to cancer: A review

Regulatory T cells (Tregs) represent a low number of T-cell population under normal conditions, and they play key roles for maintaining immune system in homeostasis. The number of these cells is extensively increased in nearly all cancers, which is for dampening responses from immune system against cancer cells, metastasis, tumor recurrence, and treatment resistance. The interesting point is that apoptotic Tregs are stronger than their live counterparts for suppressing responses from immune system. Tregs within the tumor microenvironment have extensive positive cross-talks with other immunosuppressive cells including cancer-associated fibroblasts, cancer cells, macrophage type 2 cells, and myeloid-derived suppressor cells, and they have negative interactions with immunostimulatory cells including cytotoxic T lymphocytes (CTL) and natural killer cells. A wide variety of markers are expressed in Tregs, among them forkhead box P3 (FOXP3) is the most specific marker and the master regulator of these cells. Multiple signals are activated by Tregs including transforming growth factor-β, signal transducer and activator of transcription, and mTORC1. Treg reprogramming from an immunosuppressive to immunostimulatory proinflammatory phenotype is critical for increasing the efficacy of immunotherapy. This would be applicable through selective suppression of tumor-bearing receptors in Tregs, including FOXP3, programmed death-1, T-cell immunoglobulin mucin-3, and CTL-associated antigen-4, among others. Intratumoral Tregs can also be targeted by increasing the ratio for CTL/Treg.

Nur77 promotes cerebral ischemia-reperfusion injury via activating INF2-mediated mitochondrial fragmentation

Mitochondrial fragmentation drastically regulates mitochondrial homeostasis in brain illness. However, the role of mitochondrial fragmentation in cerebral ischemia-reperfusion (IR) injury remains unclear. Nur77, a regulator of mitochondrial homeostasis, is associated with heart and liver IR injury, but its effects on mitochondrial function in cerebral IR injury has not been studied intensively. The aim of our study is to explore whether cerebral IR injury is modulated by Nur77 via modification of mitochondrial homeostasis. Our results indicated that Nur77 was upregulated in reperfused brain tissues. Genetic ablation of Nur77 reduced infarction area and promoted neuron survival under IR burden. Biochemical analysis demonstrated that Nur77 deletion protected mitochondrial function, attenuated mitochondrial oxidative stress, preserved mitochondrial potential, and blocked mitochondria-related cell apoptosis. In addition, we illustrated that Nur77 mediated mitochondrial damage via evoking mitochondrial fragmentation that occurred through increased mitochondrial fission and decreased fusion. Besides, our results also demonstrated that Nur77 controlled mitochondrial fragmentation via upregulating INF2 in a manner dependent on the Wnt/β-catenin pathway; inhibition of the Wnt pathway abrogated the protective effect of Nur77 deletion on reperfused-mediated neurons. Altogether, our study highlights that the pathogenesis of cerebral IR injury is associated with Nur77 activation followed by augmented mitochondrial fragmentation via an abnormal Wnt/β-catenin/INF2 pathway. Accordingly, Nur77-dependent mitochondrial fragmentation and the Wnt/β-catenin/INF2 axis may represent novel therapeutic targets to reduce cerebral IR injury.

Sirtuin‑1 protects hair follicle stem cells from TNFα-mediated inflammatory stress via activating the MAPK-ERK-Mfn2 pathway

OBJECTIVE

Stem cell transplantation is a promising tool to treat burn injuries. However, the inflammatory microenvironment in damaged skin limits the efficiency of stem cell-based therapy via poorly understood mechanisms. The aim of our study is to explore the contribution and mechanism of Sirtuin-1 (Sirt1) in TNFα-mediated inflammatory stress in hair follicle stem cells (HFSCs).

METHODS

Cellular viability was determined using the MTT assay, TUNEL staining, western blot analysis and LDH release assay. Adenovirus-loaded Sirt1 was transduced into HFSCs to overexpress Sirt1 in the presence of TNFα. Mitochondrial function was determined using JC-1 staining, mitochondrial ROS staining, immunofluorescence staining and western blotting.

RESULTS

Sirt1 was downregulated in response to the TNFα treatment. Additionally, TNFα stress reduced the viability, mobility and proliferation of HFSCs, and these effects were reversed by the overexpression of Sirt1. At the molecular level, Sirt1 overexpression attenuated TNFα-mediated mitochondrial damage, as evidenced by increased mitochondrial energy metabolism, decreased mitochondrial ROS generation, stabilized mitochondrial potential and blockage of the mitochondrial apoptotic pathway. Furthermore, Sirt1 modulated mitochondrial homeostasis by activating the MAPK-ERK-Mfn2 axis; inhibition of this pathway abrogated the protective effects of Sirt1 on HFSC survival, migration and proliferation.

SIGNIFICANCE

Based on our results, the inflammatory stress-mediated HFSC injury may be associated with a decrease in Sirt1 expression and subsequent mitochondrial dysfunction. Accordingly, strategies designed to enhance Sirt1 expression would be an effective approach to enhance the survival of HFSCs in the inflammatory microenvironment.

Disruption of the redox balance with either oxidative or anti-oxidative overloading as a promising target for cancer therapy

Oxidative stress acts as a double-edged sword by being both a promoter and a suppressor of cancer. Moderate oxidative stress is beneficial for cancer cell proliferative and invasiveness features, while overexposure of the cells to oxidative insults could induce cancer cell apoptosis and reduce hypoxia along with modulating the immune system for regression of tumor. Cancer cells and cancer stem cells have highly efficient redox systems that make them resistant to oxidative insults. The redox disruptive approach is an area of current research and key for oxidative targeted cancer therapies. This disruption is applicable by using either oxidative or anti-oxidative overloading strategies, specifically on cancer cells without influencing normal cells or tissues around tumor. The activity of tumor suppressor cells within tumor microenvironment is needed to be maintained in patients receiving such approaches.

Adjuvant chemotherapy with melatonin for targeting human cancers: A review

Melatonin is a multifunctional hormone that has long been known for its antitumoral effects. An advantage of the application of melatonin in cancer therapy is its ability to differentially influence tumors from normal cells. In this review, the roles of melatonin adjuvant therapy in human cancer are discussed. Combination of melatonin with chemotherapy could provide synergistic antitumoral outcomes and resolve drug resistance in affected patients. This combination reduces the dosage for chemotherapeutic agents with the subsequent attenuation of side effects related to these drugs on normal cells around tumor and on healthy organs. The combination therapy increases the rate of survival and improves the quality of life in affected patients. Cancer cell viability is reduced after application of the combinational melatonin therapy. Melatonin does all these functions by adjusting the signals involved in cancer progression, re-establishing the dark/light circadian rhythm, and disrupting the redox system for cancer cells. To achieve effective therapeutic outcomes, melatonin concentration along with the time of incubation for this indoleamine needs to be adjusted. Importantly, a special focus is required to be made on choosing an appropriate chemotherapy agent for using in combination with melatonin. Because of different sensitivities of cancer cells for melatonin combination therapy, cancer-specific targeted therapy is also needed to be considered. For this review, the PubMed database was searched for relevant articles based on the quality of journals, the novelty of articles published by the journals, and the number of citations per year focusing only on human cancers.

Wharton's jelly-derived mesenchymal cells as a new source for the generation of microtissues for tissue engineering applications

Microtissues (MT) are currently considered as a promising alternative for the fabrication of natural, 3D biomimetic functional units for the construction of bio-artificial substitutes by tissue engineering (TE). The aim of this study was to evaluate the possibility of generating mesenchymal cell-based MT using human umbilical cord Wharton's jelly stromal cells (WJSC-MT). MT were generated using agarose microchips and evaluated ex vivo during 28 days. Fibroblasts MT (FIB-MT) were used as control. Morphometry, cell viability and metabolism, MT-formation process and ECM synthesis were assessed by phase-contrast microscopy, functional biochemical assays, and histological analyses. Morphometry revealed a time-course compaction process in both MT, but WJSC-MT resulted to be larger than FIB-MT in all days analyzed. Cell viability and functionality evaluation demonstrated that both MT were composed by viable and metabolically active cells, especially the WJSC during 4-21 days ex vivo. Histology showed that WJSC acquired a peripheral pattern and synthesized an extracellular matrix-rich core over the time, what differed from the homogeneous pattern observed in FIB-MT. This study demonstrates the possibility of using WJSC to create MT containing viable and functional cells and abundant extracellular matrix. We hypothesize that WJSC-MT could be a promising alternative in TE protocols. However, future cell differentiation and in vivo studies are still needed to demonstrate the potential usefulness of WJSC-MT in regenerative medicine.

Melatonin Inhibits Reactive Oxygen Species-Driven Proliferation, Epithelial-Mesenchymal Transition, and Vasculogenic Mimicry in Oral Cancer

Globally, oral cancer is the most common type of head and neck cancers. Melatonin elicits inhibitory effects on oral cancer; however, the biological function of melatonin and underlying mechanisms remain largely unknown. In this study, we found that melatonin impaired the proliferation and apoptosis resistance of oral cancer cells by inactivating ROS-dependent Akt signaling, involving in downregulation of cyclin D1, PCNA, and Bcl-2 and upregulation of Bax. Melatonin inhibited the migration and invasion of oral cancer cells by repressing ROS-activated Akt signaling, implicating with the reduction of Snail and Vimentin and the enhancement of E-cadherin. Moreover, melatonin hampered vasculogenic mimicry of oral cancer cells through blockage of ROS-activated extracellular-regulated protein kinases (ERKs) and Akt pathways involving the hypoxia-inducible factor 1α. Consistently, melatonin retarded tumorigenesis of oral cancer in vivo. Overall, these findings indicated that melatonin exerts antisurvival, antimotility, and antiangiogenesis effects on oral cancer partly by suppressing ROS-reliant Akt or ERK signaling.

Melatonin and Cancer Hallmarks

Melatonin is a natural indoleamine produced by the pineal gland that has many functions, including regulation of the circadian rhythm. Many studies have reported the anticancer effect of melatonin against a myriad of cancer types. Cancer hallmarks include sustained proliferation, evading growth suppressors, metastasis, replicative immortality, angiogenesis, resisting cell death, altered cellular energetics, and immune evasion. Melatonin anticancer activity is mediated by interfering with various cancer hallmarks. This review summarizes the anticancer role of melatonin in each cancer hallmark. The studies discussed in this review should serve as a solid foundation for researchers and physicians to support basic and clinical studies on melatonin as a promising anticancer agent.