Youwu Fan

The involvement of Nrf2–ARE pathway in regulation of apoptosis in human glioblastoma cell U251

Abstract Objectives: NF-E2-related factor 2 (Nrf2)–antioxidant response element (ARE) pathway plays anti-apoptotic role in normal tissue and tumor. But the role of Nrf2 in apoptosis in glioma is still unknown. Here, we established this experiment to elucidate how Nrf2–ARE pathway participates in apoptosis in human glioblastoma cell U251. Methods: Two plasmids, pEGFP-Nrf2 and Si-Nrf2, were transfected to up- or downregulate the expression of Nrf2 in U251. After transfection, the apoptosis rate, expression of heme oxygenase-1 (HO-1), Bcl-2, Bax, caspases 3, 9 and activity of caspases 3, 9 were detected. Results: After increasing expression of Nrf2, the apoptosis rate was reduced accompanied with upregulated expression of HO-1, Bcl-2/Bax, decreased expression and activity of caspases 3, 9. After decreasing expression of Nrf2, the apoptosis rate was enhanced accompanied with downregulated expression of HO-1, Bcl-2/Bax, increased expression and activity of caspases 3, 9. Discussion: Our findings suggest that Nrf2 participates in the regulation of apoptosis in U251 through HO-1 and the ‘intrinsic’ apoptotic pathway.

Fucoxanthin provides neuroprotection in models of traumatic brain injury via the Nrf2-ARE and Nrf2-autophagy pathways

Fucoxanthin is abundant in seaweed and is considered as a powerful antioxidant. It has been proposed to possess anti-cancer, anti-obesity and anti-diabetes effects. However, its roles in brain injury models have not been fully understood. The objective of this study was to investigate the neuroprotection of fucoxanthin in models of traumatic brain injury (TBI) and the role of the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant-response element (ARE) and Nrf2-autophagy pathways in the putative neuroprotection. We found that fucoxanthin alleviated TBI-induced secondary brain injury, including neurological deficits, cerebral edema, brain lesion and neuronal apoptosis. Moreover, the up-regulation of malondialdehyde (MDA) and the activity of glutathione peroxidase (GPx) were reversed by fucoxanthin treatment. Furthermore, our in vitro studies demonstrated that fucoxanthin increased the neuron survival and reduced the reactive oxygen species (ROS) level. In addition, fucoxanthin activated the Nrf2-ARE pathway and autophagy both in vivo and in vitro, which was proven by the results of immunohistochemistry, western blot and electrophoretic mobility shift assay (EMSA). However, fucoxanthin failed to provide neuroprotection and activated autophagy following TBI in Nrf2−/− mice. In conclusion, our studies indicated that fucoxanthin provided neuroprotective effects in models of TBI, potentially via regulation of the Nrf2-ARE and Nrf2-autophagy pathways.

Protective Effects of Quercetin on Mitochondrial Biogenesis in Experimental Traumatic Brain Injury via the Nrf2 Signaling Pathway

The present investigation was carried out to elucidate a possible molecular mechanism related to the protective effect of quercetin administration against oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of nuclear factor erythroid 2-related factor 2 (Nrf2) in mitochondrial biogenesis. Recently, quercetin has been proved to have a protective effect against mitochondria damage after traumatic brain injury (TBI). However, its precise role and underlying mechanisms in traumatic brain injury are not yet fully understood. The aim of the present study was to investigate the effect of quercetin on the potential mechanism of these effects in a weight-drop model of TBI in male mice that were treated with quercetin or vehicle via intraperitoneal injection administrated 30 min after TBI. In this experiment, ICR mice were divided into four groups: A sham group, TBI group, TBI + vehicle group, and TBI + quercetin group. Brain samples were collected 24 h later for analysis. Quercetin treatment resulted in an upregulation of Nrf2 expression and cytochrome c, malondialdehyde (MDA) and superoxide dismutase (SOD) levels were restored by quercetin treatment. Quercetin markedly promoted the translocation of Nrf2 protein from the cytoplasm to the nucleus. These observations suggest that quercetin improves mitochondrial function in TBI models, possibly by activating the Nrf2 pathway.

Zinc as mediator of ubiquitin conjugation following traumatic brain injury

Previous studies have shown that pathological zinc accumulation and deposition of ubiquitinated protein aggregates are commonly detected in many acute neural injuries, such as trauma, epilepsy and ischemia. However, the underlying mechanisms are poorly understood. Here we assessed the effect of zinc on ubiquitin conjugation and subsequent neurodegeration following traumatic brain injury (TBI). First, we found that scavenging endogenous Zn(2+) reduced trauma-induced ubiquitin conjugation and protected neurons from TBI insults in rat hippocampus. Second, we detected both zinc accumulation and increased ubiquitin conjugated protein following brain trauma in human cortical neurons. Our previous study has shown that zinc can induce ubiquitin conjugation in cultured hippocampal neurons. All these findings indicate that alterations in Zn(2+) homeostasis may impair the protein degradation pathway and ultimately cause neuronal injury following traumatic brain injury.

Intracranial meningeal melanocytoma associated with nevus of Ota

We report a rare intracranial meningeal melanocytoma associated with the nevus of Ota. The patient was 36-year-old man with a 2-week history of headache and difficulty in opening his right eye. Physical examination showed a black nevus scattered on the right-hand side of the face, right eyelid ptosis and papilledema. CT scans and MRI showed a tumor in the region of the right cavernous sinus. The tumor was subtotally resected. Histological examination confirmed the diagnosis of melanocytoma.

Quercetin sensitizes glioblastoma to t-AUCB by dual inhibition of Hsp27 and COX-2 in vitro and in vivo

BackgroundEvidences indicate that inflammatory process plays pivotal role in tumor disease. Soluble epoxide hydrolase inhibitors (sEHIs) have been shown to participate in anti-inflammation and tumorigenesis by protecting epoxyeicosatrienoic acids (EETs). Although we have previously revealed some effects of t-AUCB on glioma in vitro, further investigations are needed to demonstrate its effects on glioblastoma growth in vivo and how to strengthen its antitumor effect.MethodsCCK-8 kit was used to test cell growth. Cell migration capacity was performed by wound healing assays. Transwell assay was used to test cell invasion potency. Cell-cycle analysis and cell apoptosis was performed by flow cytometry. The activity of caspase-3 in cells was measured using caspase-3 activity assay kits. Total RNA was extracted from cells lysated by TRIzol reagent. qRT-PCR was performed by ABI 7500 fast RT- PCR system. Lipofectamine RNAiMAX Transfection Reagent (Invitrogen) was used for siRNA transfection. Western blootting was used to test protein expression. Tumor cell xenograft mouse models were used for in vivo study. The SPSS version 17.0 software was applied for statistical analysis.ResultsOur data shown that t-AUCB inhibits cell proliferation, migration and invasion and induces cell cycle G1 phase arrest in vitro but induces no cell apoptosis; increased Hsp27 activation and following COX-2 overexpression confer resistance to t-AUCB treatment in glioblastoma both in vitro and in vivo; quercetin sensitizes glioblastoma to t-AUCB by dual inhibition of Hsp27 and COX-2 in vitro and in vivo.ConclusionsThese results indicate that combination of t-AUCB and quercetin may be a potential approach to treating glioblastoma.

Targeting the NF-E2-related factor 2 pathway: a novel strategy for glioblastoma (review).

Glioblastoma is the most common and malignant subtype among all brain tumors. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential component of cellular defense against a variety of endogenous and exogenous stresses. A marked increase in research over the past few decades focusing on Nrf2 and its role in regulating glioblastoma has revealed the potential value of Nrf2 in the treatment of glioblastoma. In the present review, we discuss a novel framework of Nrf2 in the regulation of glioblastoma and the mechanisms regarding the downregulation of Nrf2 in treating glioblastoma. The candidate mechanisms include direct and indirect means. Direct mechanisms target tumor molecular pathways in order to overcome resistance to chemotherapy and radiotherapy, to inhibit proliferation, to block invasion and migration, to induce apoptosis, to promote differentiation, to enhance autophagy and to target glioblastoma stem cells. Indirect mechanisms target the reaction between glioblastoma cells and the surrounding microenvironment. Overall, the value of the Nrf2 pathway in glioblastoma provides a promising opportunity for new approaches by which to treat glioblastoma.

Quercetin blocks t-AUCB-induced autophagy by Hsp27 and Atg7 inhibition in glioblastoma cells in vitro

We previously demonstrated that the acquired resistance because of Hsp27 activation weakens the cytotoxic effect of t-AUCB on glioblastoma cells. Since autophagy is regarded as a survival mechanism for cells exposed to cytotoxic agents, the aim of this study is to investigate whether t-AUCB induces autophagy and whether Hsp27 and autophagy are interacted with each other. Our data demonstrated that t-AUCB induces autophagy in glioblastoma cells and regulates multiple autophagy related-gene expression. t-AUCB induces overexpression of Atg7, which is downstream of Hsp27 and participates in the resistance of glioblastoma cells to t-AUCB treatment. Hsp27 inhibitor quercetin suppresses Atg7 expression and strengthens t-AUCB-induced cell death by autophagy blockage. We concluded that combination of quercetin and t-AUCB might be a potential strategy for glioblastoma treatment.

Neuroprotection by quercetin via mitochondrial function adaptation in traumatic brain injury: PGC-1α pathway as a potential mechanism

The aim of this study was to investigate the neuroprotective effects of quercetin in mouse models of traumatic brain injury (TBI) and the potential role of the PGC‐1α pathway in putative neuroprotection. Wild‐type mice were randomly assigned to four groups: the sham group, the TBI group, the TBI+vehicle group and the TBI+quercetin group. Quercetin, a dietary flavonoid used as a food supplement, significantly reduced TBI‐induced neuronal apoptosis and ameliorated mitochondrial lesions. It significantly accelerated the translocation of PGC‐1α protein from the cytoplasm to the nucleus. In addition, quercetin restored the level of cytochrome c, malondialdehyde and superoxide dismutase in mitochondria. Therefore, quercetin administration can potentially attenuate brain injury in a TBI model by increasing the activities of mitochondrial biogenesis via the mediation of the PGC‐1α pathway.

Chryseobacterium indologenes catheter-related meningitis in an elderly patient after intracranial aneurysm clipping surgery

Chryseobacterium indologenes is a Gram-negative, nonmotile, indole-positive, non-glucose-fermenting bacillus that is widely distributed in nature [1]. It was first isolated by Bonten [2] from a tracheal aspirate in a patient with ventilator-associated pneumonia. It has been reported to cause a variety of infections usually in immunosuppressed adult patients, in infants, or in patients with indwelling devices [3]. Here, we present a case of an elderly patient who had severe meningitis caused by C. indologenes.