Artemether Attenuates Aβ25-35-Induced Cognitive Impairments by Downregulating Aβ, BACE1, mTOR and Tau Proteins

BACKGROUND

Alzheimer's disease (AD) is clinically characterized as a progressive cognitive impairment and behavioral disorder. Pathological hallmarks of AD include extracellular senile plaques (SPs), intracellular neurofibrillary tangles (NFTs) and massive neuronal loss. Although the exact cause of AD is not well understood, a mounting body of evidence has demonstrated that the pathogenesis of AD is associated with oxidative stress, neu-roinflammation, and amyloid beta (Aβ) induced neural apoptosis. Moreover, overexpression of β-secretase 1 (BACE1), Aβ, mammalian target of rapamycin (mTOR), and Tau proteins are closely related to cognitive symptoms in AD. Studies have demonstrated that artemether, an antimalarial drug with acceptable side effects, possesses protective effects against neuroinflammation and oxidative stress. Importantly, artemether can easily penetrate the blood brain barrier, thereby representing an ideal drug candidate for AD treatment.

METHODS

The effect of artemether on memory protection and the associated molecular mechanisms were investigated in an Aβ25-35 induced cognitive impairments rat model.

RESULTS

Results of the in vivo study showed that oral administration of artemether significantly attenuated Aβ25-35-induced cognitive impairment in rats. Results of the in vitro study revealed that artemether significantly downregulated the endogenous expression of Aβ, BACE1, mTOR, and Tau proteins in N2a cells.

CONCLUSIONS

The beneficial effect of artemether against Aβ 25-35-induced cognitive impairments was attributable to the downregulation of the expression of Aβ, BACE1, mTOR, and Tau proteins, suggesting the potential of artemether as an effective, neuronal protective, and multi-targeted drug candidate for AD treatment.

The Association of microRNA-34a With High Incidence and Metastasis of Lung Cancer in Gejiu and Xuanwei Yunnan

The incidence and associated mortality of lung cancer in tin miners in Gejiu County and farmers in Xuanwei Country, Yunnan Province have been very high in the world. Current published literatures on the molecular mechanisms of lung cancer initiation and progression in Gejiu and Xuanwei County are still controversial. Studies confirmed that microRNA-34a (miR-34a) functioned as a vital tumor suppressor in tumorigenesis and progression. However, the role and precise mechanisms of miR-34a and its regulatory gene network in initiation and progression of lung cancer in Gejiu and Xuanwei County, Yunnan Province, have not been elucidated. In the current study, we first found that miR-34a was downregulated in Gejiu lung squamous carcinoma YTMLC-90, Xuanwei lung adenocarcinoma XWLC-05, and other non-small cell lung carcinoma (NSCLC) cell lines, and miR-34a overexpression inhibited cell proliferation, migration and invasion, as well as induced cell apoptosis in YTMLC-90 and XWLC-05 cells. Our findings revealed that miR-34a is critical and cannot be considered as the area-specific non-coding RNA in initiation and progression of lung cancer in Gejiu and Xuanwei County. Next we revealed that miR-34a overexpression suppressed lung cancer growth and metastasis partially via increasing PTEN but reducing CDK6 expression that might lead to subsequent inactivation of PI3K/AKT pathway. Furthermore, our findings demonstrated that YY1 functioned as a tumor suppressor gene in initiation and progression of lung cancer in Gejiu and Xuanwei County. In conclusion, our findings in the study confirmed that miR-34a overexpression could simultaneously suppress tumor growth and metastasis and play a vital role in tumorigenesis and progression of NSCLC via increasing PTEN and YY1 expression, but decreasing CDK6. Most interestingly, our findings also raised doubts about the current ideas about these area-specific diseases.

Effects and mechanism of microRNA‑218 against lung cancer

Lung cancer is the most prevalent and observed type of cancer in Xuanwei County, Yunnan, South China. Lung cancer in this area is called Xuanwei lung cancer. However, its pathogenesis remains largely unknown. To date, a number of studies have shown that microRNA (miR)‑218 functions as a tumor suppressor in multiple types of cancer. However, the role of miR‑218 and its regulatory gene network in Xuanwei lung cancer have yet to be investigated. The current study identified that the expression levels of miR‑218 in XWLC‑05 cells were markedly lower compared with those in immortalized lung epithelial BEAS‑2B cells. The present study also demonstrated that overexpression of miR‑218 could decrease cell proliferation, invasion, viability and migration in Xuanwei lung cancer cell line XWLC‑05 and NSCLC cell line NCI‑H157. Additionally, the results revealed that overexpression of miR‑218 could induce XWLC‑05 and NCI‑H157 cell apoptosis by arresting the cell cycle at G2/M phase. Finally, the present study demonstrated that overexpression of miR‑218 could lead to a significant increase in phosphatase and tensin homolog (<em>PTEN</em>) and YY1 transcription factor (<em>YY1</em>), and a decrease in B‑cell lymphoma 2 (<em>BCL‑2</em>) and BMI1 proto‑oncogene, polycomb ring finger (<em>BMI‑1</em>) at the mRNA and protein level in XWLC‑05 and NCI‑H157 cell lines. However, we did not observe any remarkable difference in the roles of miR‑218 and miR‑218‑mediated regulation of <em>BCL‑2</em>, <em>BMI‑1</em>, <em>PTEN</em> and <em>YY1</em> expression in the progression of Xuanwei lung cancer. In conclusion, miR‑218 could simultaneously suppress cell proliferation and tumor invasiveness and induce cell apoptosis by increasing <em>PTEN</em> and <em>YY1</em> expression, while decreasing <em>BCL‑2</em> and <em>BMI‑1</em> in Xuanwei lung cancer. The results demonstrated that miR‑218 might serve a vital role in tumorigenesis and progression of Xuanwei lung cancer and overexpression of miR‑218 may be a novel approach for the treatment of Xuanwei lung cancer.

Synthesis, Crystal Structure, Photophysical Properties and Theoretical Study of a New Iridium(III) Complex Containing 2-phenylbenzothiazole Ligand

A new bis-cyclometalated iridium(III) complex [Ir(dmabt)(2)(bipy)][PF(6)] (3) (dmabt = 4-(benzo[d]thiazol-2-yl)-N,N-dimethylaniline, bipy = 2,2'-bipyridine) has been synthesized and fully characterized. The complex 3 has been determined by X-ray structure analyses which shows that the central iridium(III) ion assumes distorted octahedral geometry. The photoluminescence spectrum exhibits orange emission maximum at 612 nm with quantum yield of 17% at 298 K. The frontier molecular orbital diagrams and the spin-allowed singlet-singlet electronic transitions of 3 have been calculated with density functional theory (DFT) and time-dependent DFT (TD-DFT), and the UV-Vis spectra are discussed based on the theoretical calculations.

Inhibitive effect of artemether on tumor growth and angiogenesis in the rat C6 orthotopic brain gliomas model

To explore the inhibitive effect of artemether on glioma growth and angiogenesis in brain tumor bearing SD rat. MTT assay was used to evaluate the inhibitory effect of artemether treatment on C6 glioma cells. Forty SD rats which were subcutaneous planted with SD rat C6 glioma cell to establish SD rat orthotopic glioma model were divided resourcefully into 5 groups. each group was 8 rats. Length-path (a mm) and short-path (b mm) of tumor each rat was measured. Tumor volume was calculated using the following formula: V (mm(3)) = a(2)bpi/6. Microvessel density (MVD) in different therapy groups was significantly lower than that in normal saline control group and brain glioma volume in different therapy groups was significantly smaller than that in normal saline control group. There were remarkably inhibitory effects of artmeter on brain glioma growth and angiogenesis in SD rats and the mechanism that artemether inhibited brain glioma growth might be penetrating the blood-brain barrier and inhibiting angiogenesis.

The Structures of New Peptides From the Australian Red Tree Frog 'Litoria rubella'. The Skin Peptide Profile as a Probe for the Study of Evolutionary Trends of Amphibians

Seventeen peptides have been isolated and characterized from specimens of the red tree frog 'Litoria rubella', collected from 15 locations throughout Australia. These can be classified into two families of peptides, viz. ( i ) the tryptophyllins L, of which Phe Pro Trp Leu (NH2), Phe Pro Trp Pro (NH2) and pGlu Phe Pro Trp Pro (NH2) are the major constituents, (ii) two types of rubellidins, the first of which is unique to 'Litoria rubella' [e.g. Val Asp Phe Phe Ala (OH)], and the second [e.g. Gly Leu Gly Asp Ile Leu Gly Leu Leu Gly Leu (NH2)], containing peptides of the caeridin type (like those isolated from Litoria caerulea and Litoria splendida). These peptides show no significant antimicrobial activity. The tryptophyllins are thought to be neuromodulators or neurotransmitters, but the roles of the anionic rubellidin peptides in the amphibian integument are not understood. A comparison of the skin peptide profiles of live specimens of 'Litoria rubella' collected from different locations suggests that there are a number of discrete populations (perhaps different species or subspecies) in ( i ) an area from Kakadu National Park to the Adelaide River in the Northern Territory, (ii) in and around Alice Springs, (iii) in the north of South Australia, and (iv) in several areas of the Kimberley region of Western Australia. In addition, there appear to be evolving populations along the eastern seaboard of Queensland.

The Structures of Four Tryptophyllin and Three Rubellidin Peptides From the Australian Red Tree Frog Litoria rubella

The peptide content of the glandular secretions of Litoria rubella specimens collected from Derby and Lake Argyle (Kimberley region of Western Australia) and from near Darwin in the Northern Territory are all quite different; this suggests that there are different frog populations in these three areas. These different populations may be indicative of either different species or different sub-species of frog. There are two separate families of peptides in the glandular secretion of 'Litoria rubella': ( i ) those corresponding to the tryptophyllin family (tetra- to hepta -peptides all containing the residues Pro and Trp ), and (ii) the rubellidinins ( pentapeptides all containing two Phe residues at positions 3 and 4). To ate, no biological activity has been found for any of these peptides, but it is suspected that the tryptophyllins may be neurotransmitters or neuromodulators.