Possible involvement of NAMPT in neuronal survival in cerebral ischemic injury under high-glucose conditions through the FoxO3a/LC3 pathway.

The incidence of cerebral infarction triggered by abnormal glucose tolerance has increased; however, the relationship between glucose concentration in the brain and the detailed mechanism of post ischemic cell death remains unclear. Nicotinamide phosphoribosyltransferase (NAMPT), an adipocytokine, is the rate-limiting enzyme for NAD+ synthesis in the salvage pathway. Although NAMPT activation prevents neuronal injury, the relationship between NAMPT activity, glucose metabolism disorders, and cerebral ischemia-induced neuronal cell death is unknown. In this study, we determined changes in NAMPT on cerebral ischemic injuries with diabetes using a db/db mouse model of type 2 diabetes and then identified the underlying mechanisms using Neuro2a cells. The expression of inflammatory cytokine mRNAs was increased in db/db and db/+ middle cerebral artery occlusion and reperfusion (MCAO/R) mice. Although NeuN-positive cells were decreased after MCAO/R, the number of NAMPT and NeuN double-positive cells in NeuN-positive neuronal cells increased in db/db MCAO/R mice. Next, the role of NAMPT in Neuro2a cells under conditions of high glucose (HGC) and oxygen-glucose deprivation (OGD), which mimics diabetes-complicated cerebral infarction, was examined. Treatment with P7C3-A20, a NAMPT activator, suppressed the decrease in cell viability caused by HGC/OGD; however, there were no significant differences in the levels of cleaved caspase-3 and Bax proteins. Moreover, increased FoxO3a and LC3-II levels after HGC/OGD were inhibited by P7C3-A20 treatment. Our findings indicate that NAMPT activation is associated with neuronal survival under ischemic conditions with abnormal glucose tolerance through the regulation of FoxO3a/LC3.

Role of senkyunolide I in the promotion of neural stem/progenitor cell proliferation via the Akt/ß-catenin pathway.

Following brain injury, neural stem cells (NSCs) can generate mature neurons and replace damaged cells. However, the capacity of endogenous NSCs to self-repair from injured brain is limited as most NSCs die before becoming mature neurons. Therefore, a boosting endogenous NSCs by pharmacological support offers the potential to repair the damaged brain. Recently, small molecules have hold considerable promise for neuron regeneration and repair as they can penetrate the blood-brain barrier easily. Senkyunolide I (SEI) is a bioactive constituent derived from traditional Chinese medicines Ligusticum chuanxiong Hort. and Angelica sinensis (Oliv.) Diels, and was found to able to prevent ischemic stroke. This study examined the effects of SEI on the proliferation and neuronal lineage differentiation of prepared neural stem/progenitor cells (NS/PCs). The NS/PC proliferation was determined by 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt, and neurosphere formation assays. The NS/PC differentiation was also investigated by immunocytochemistry, and western blotting was employed to measure phosphorylated Akt (pAkt) and GSK-3ß (pGSK-3ß), and active-ß-catenin protein levels. We showed that the NS/PC proliferation was enhanced after SEI exposure. Elevated cell numbers were also observed in neurospheres, which were incubated with SEI for 3 days, whereas the NS/PC differentiation was decreased after SEI exposure for 5 days. Furthermore, SEI upregulated pAkt/Akt and active-ß-catenin levels and increased NS/PC proliferation after SEI treatment was reversed by phosphatidylinositol 3-kinase inhibitor LY294002. downregulated differentiated processes. Thus, SEI promoted the NS/PC proliferation and suppressed NS/PC differentiation into neurons and/or astrocytes, therefore SEI could be an interesting and promising candidate for stimulating NSCs.

Cytotoxic Effects of Hellebrigenin and Arenobufagin Against Human Breast Cancer Cells.

Development of new therapeutic strategies for breast cancer is urgently needed due to the sustained emergence of drug resistance, tumor recurrence and metastasis. To gain a novel insight into therapeutic approaches to fight against breast cancer, the cytocidal effects of hellebrigenin (Helle) and arenobufagin (Areno) were investigated in human estrogen receptor (ER)-positive breast cancer cell line MCF-7 and triple-negative breast cancer cell line MDA-MB-231. Helle exhibited more potent cytotoxicity than Areno in both cancer cells, and MCF-7 cells were more susceptible to both drugs in comparison with MDA-MB-231 cells. Apoptotic-like morphological characteristics, along with the downregulation of the expression level of Bcl-2 and Bcl-xL and the upregulation of the expression level of Bad, were observed in Helle-treated MCF-7 cells. Helle also caused the activation of caspase-8, caspase-9, along with the cleavage of poly(ADP-ribose) polymerase in MCF-7 cells. Helle-mediated necrosis-like phenotype, as evidenced by the increased propidium iodide (PI)-positive cells was further observed. G2/M cell cycle arrest was also induced by Helle in the cells. Upregulation of the expression level of p21 and downregulation of the expression level of cyclin D1, cyclin E1, cdc25C and survivin were observed in MCF-7 cells treated with Helle and occurred in parallel with G2/M arrest. Autophagy was triggered in MCF-7 cells and the addition of wortmannin or 3-MA, two well-known autophagy inhibitors, slightly but significantly rescued the cells. Furthermore, similar alterations of some key molecules associated with the aforementioned biological phenomena were observed in MDA-MB-231 cells. Intriguingly, the numbers of PI-positive cells in Helle-treated MCF-7 cells were significantly reduced by wortmannin and 3-MA, respectively. In addition, Helle-triggered G2/M arrest was significantly corrected by wortmannin, suggesting autophagy induction contributed to Helle-induced cytotoxicity of breast cancer cells by modulating necrosis and cell cycle arrest. Collectively, our results suggested potential usefulness of both Helle and Areno in developing therapeutic strategies to treat patients with different types of breast cancer, especially ER-positive breast cancer.

Neuroprotective effects of Senkyunolide I against glutamate-induced cells death by attenuating JNK/caspase-3 activation and apoptosis.

Glutamate-induced neurotoxicity is one of the most important pathogenic mechanisms in neurological diseases and is widely used as an in vitro model for ischemic stroke. Senkyunolide I (SEI), an active constituent derived from traditional Chinese medicine Ligusticum chuanxiong Hort. and Angelica sinensis (Oliv.) Diels, has been shown to have beneficial effects against focal cerebral ischemia-reperfusion in rats. However, the mechanisms underlying SEI-mediated neuroprotection remain not well understood. Thus, we explored the influence of SEI in glutamate-mediated injury to mouse neuroblastoma (Neuro2a) cells and determined the mechanisms involved. Neuro2a cells were treated with SEI under exposure to glutamate for 24 h. Cell viability was assessed by using WST-1 reagents, and apoptosis was evaluated using Annexin V-FITC and a PI double staining kit. The protein expression levels of p-AKT, AKT, p-GSK3ß, GSK3ß, p-p38, p38, p-ERK, ERK, p-JNK, JNK, Bcl-2, Bax, Bcl-xl, p-Bad, Bad, p53, and cleaved caspase-3 were determined by Western blot analysis. Glutamate significantly decreased cell viability and elevated the level of apoptosis. Treatment with SEI reversed those effects. Furthermore, the expression of p-JNK/JNK and cleaved caspase-3 were also reduced after treatment with SEI. Our findings demonstrate that SEI protected Neuro2a cells against glutamate toxicity by regulating JNK/caspase-3 pathway and apoptosis. Thus, SEI maybe a promising candidate for neuroprotection.