Aplysin enhances temozolomide sensitivity in glioma cells by increasing miR-181 level

Dithioallyl Cations in Stereoselective Dearomative (3 + 2) Cycloadditions of Benzofurans: Mechanism and Synthetic Applications

A stereoselective dearomative cyclopentannulation of benzofurans is reported. A previously reported dearomative (3 + 2) cycloaddition of indoles with 1,4-dithiane-fused allyl cations was found to lack stereoselectivity when more substituted cyclopentene rings are targeted. However, for benzofuran substrates, excellent levels of stereoselectivity were observed for the same allyl cation reagents under very similar reaction conditions. In this full account, we provide a mechanistic rationale and some design principles that govern the stereoselectivity of the intriguing dearomative transformations using dithioallyl cations and demonstrate how the stereoselectivity depends on electronic factors of the starting materials. The stereoselective methodology is also applied in a straightforward dearomative synthesis of the tricyclic sesquiterpenoid natural product aplysin and its analogues, starting from a simple benzofuran.

Anticancer Effects of Fucoxanthin through Cell Cycle Arrest, Apoptosis Induction, Angiogenesis Inhibition, and Autophagy Modulation

Cancer accounts for one in seven deaths worldwide and is the second leading cause of death in the United States, after heart disease. One of the standard cancer treatments is chemotherapy which sometimes can lead to chemoresistance and treatment failure. Therefore, there is a great need for novel therapeutic approaches to treat these patients. Novel natural products have exhibited anticancer effects that may be beneficial in treating many kinds of cancer, having fewer side effects, low toxicity, and affordability. Numerous marine natural compounds have been found to inhibit molecular events and signaling pathways associated with various stages of cancer development. Fucoxanthin is a well-known marine carotenoid of the xanthophyll family with bioactive compounds. It is profusely found in brown seaweeds, providing more than 10% of the total creation of natural carotenoids. Fucoxanthin is found in edible brown seaweed macroalgae such as Undaria pinnatifida, Laminaria japonica, and Eisenia bicyclis. Many of fucoxanthin's pharmacological properties include antioxidant, anti-tumor, anti-inflammatory, antiobesity, anticancer, and antihypertensive effects. Fucoxanthin inhibits many cancer cell lines' proliferation, angiogenesis, migration, invasion, and metastasis. In addition, it modulates miRNA and induces cell cycle growth arrest, apoptosis, and autophagy. Moreover, the literature shows fucoxanthin's ability to inhibit cytokines and growth factors such as TNF-α and VEGF, which stimulates the activation of downstream signaling pathways such as PI3K/Akt autophagy, and pathways of apoptosis. This review highlights the different critical mechanisms by which fucoxanthin inhibits diverse cancer types, such as breast, prostate, gastric, lung, and bladder development and progression. Moreover, this article reviews the existing literature and provides critical supportive evidence for fucoxanthin's possible therapeutic use in cancer.

miR-16 Inhibits Extracellular Signal-Regulated Kinases (ERK) Mitogen-Activated Protein Kinases (MAPK) Signaling to Affect Epithelial-Mesenchymal Transition (EMT) and Invasion of Glioma Cells

Abnormal MEK1 expression is associated with tumor cell EMT, invasion and metastasis. Decreased miR-16 level is associated with glioma. Bioinformatics analysis showed a relationship between miR-16 and MEK1. This study assessed whether miR-16 regulates MEK1 expression and affects glioma cell EMT and invasion. The tumor tissues and adjacent glioma tissues were collected to measure miR-16 and MEK1 mRNA. The dual luciferase assay validated the relation of miR-16 with MEK1. U251 cells were cultured and assigned into NC group and mimic group, followed by analysis of cell biological behaviors, and MEK1, p-ERK1/2, E-cadherin, N-Cadherin expression. Compared with adjacent tissues, miR-16 expression was significantly decreased and MEK1 was elevated in glioma tissues. Compared with HEB, miR-16 in glioma U251 and SHG44 cells was decreased and MEK1 was increased. Dual luciferase reporter gene experiments confirmed the relation of miR-16 with MEK1. Transfection of miR-16 mimic significantly down-regulated MEK1, p-ERK1/2 and N-cadherin in U251 cells, upregulated E-cadherin, inhibited cell proliferation, promoted apoptosis, and attenuated EMT and invasion of glioma cells. In conclusion, decreased miR-16 expression and increased MEK1 expression is related to glioma pathogenesis. Overexpression of miR-16 can inhibit MEK1 expression, ERK/MAPK signaling, glioma cell proliferation, promote apoptosis, and attenuate EMT and invasion.

Bioactive Compounds with Antiglioma Activity from Marine Species

The search for new chemical compounds with antitumor pharmacological activity is a necessary process for creating more effective drugs for each specific malignancy type. This review presents the outcomes of screening studies of natural compounds with high anti-glioma activity. Despite significant advances in cancer therapy, there are still some tumors currently considered completely incurable including brain gliomas. This review covers the main problems of the glioma chemotherapy including drug resistance, side effects of common anti-glioma drugs, and genetic diversity of brain tumors. The main emphasis is made on the characterization of natural compounds isolated from marine organisms because taxonomic diversity of organisms in seawaters significantly exceeds that of terrestrial species. Thus, we should expect greater chemical diversity of marine compounds and greater likelihood of finding effective molecules with antiglioma activity. The review covers at least 15 classes of organic compounds with their chemical formulas provided as well as semi-inhibitory concentrations, mechanisms of action, and pharmacokinetic profiles. In conclusion, the analysis of the taxonomic diversity of marine species containing bioactives with antiglioma activity is performed noting cytotoxicity indicators and to the tumor cells in comparison with similar indicators of antitumor agents approved for clinical use as antiglioblastoma chemotherapeutics.

microRNA-1296 Inhibits Glioma Cell Growth by Targeting ABL2

Aberrant expression of microRNAs (miRNAs) has been reported to play a role in tumorigenesis. Dysfunction of miR-1296 was found in a variety of cancers, however, the function of miR-1296 in the progression of glioma remains largely understood. Here, our results showed that miR-1296 was significantly down-regulated in glioma tissues and cell lines. Decreased expression of miR-1296 was associated with the tumor size, WHO grade and karnofsky performance scale (KPS) of glioma patients. Low expression of miR-1296 was significantly correlated with the shorter 5-year overall survival of glioma patients. Overexpression of miR-1296 inhibited the proliferation, colony formation, migration and induced apoptosis of glioma cells. MiR-1296 was found to bind the 3’-untranslated region (UTR) of ABL proto-oncogene 2 (ABL2) and subsequently repressed both the mRNA and protein expression of ABL2. ABL2 was overexpressed in glioma tissues and inversely correlated with that of miR-1296. Ectopic expressed ABL2 could reverse the inhibitory effects of miR-1296 on glioma cell proliferation. Our results illustrated the novel tumor-suppressive function of miR-1296 in glioma via repressing ABL2, suggesting a potential application of miR-1296 in the treatment of glioma.

Targeting miRNAs by natural products: A new way for cancer therapy

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression through mRNA degradation or translation inhibition. MiRNAs play important roles in a variety of biological processes, and dysregulation of miRNA expression is highly associated with cancer development. Individual miRNA regulates multiple gene expressions, enabling them to regulate multiple cellular signaling pathways simultaneously. Hence, miRNAs could be served as cancer biomarkers for diagnosis and prognosis, and also therapeutic targets. Recently, more and more evidences showed that natural products such as paclitaxel, curcumin, resveratrol, genistein or epigallocatechin-3-gallate exert their anti-proliferative and/or pro-apoptotic effects through regulating one or more miRNAs, leading to the inhibition of cancer cell growth, induction of apoptosis or enhancement of conventional cancer therapeutic efficacy. Herein, we outlined the recent advances in the regulation of miRNAs expression by the natural products and highlight the importance of these natural drugs as a potential strategy in cancer treatment. This review will help us better understand how natural products modulate miRNAs and contribute to the development of effective and safe natural drugs for therapeutic purposes.

Antimycobacterial Activity of Laurinterol and Aplysin from Laurencia johnstonii

Marine environments represent a great opportunity for the discovery of compounds with a wide spectrum of bioactive properties. Due to their large variety and functions derived from natural selection, marine natural products may allow the identification of novel drugs based not only on newly discovered bioactive metabolites but also on already known compounds not yet thoroughly investigated. Since drug resistance has caused an increase in infections by Mycobacterium tuberculosis and nontuberculous mycobacteria, the re-evaluation of known bioactive metabolites has been suggested as a good approach to addressing this problem. In this sense, this study presents an evaluation of the in vitro effect of laurinterol and aplysin, two brominated sesquiterpenes isolated from Laurencia johnstonii, against nine M. tuberculosis strains and six nontuberculous mycobacteria (NTM). Laurinterol exhibited good antimycobacterial activity, especially against nontuberculous mycobacteria, being remarkable its effect against Mycobacterium abscessus, with minimum inhibitory concentration (MIC) values lower than those of the reference drug imipenem. This study provides further evidence for the antimycobacterial activity of some sesquiterpenes from L. johnstonii, which can be considered interesting lead compounds for the discovery of novel molecules to treat NTM infections.

Computational Outlook of Marine Compounds as Anti-Cancer Representatives Targeting BCL-2 and Survivin

INTRODUCTION

The regulation of apoptosis via compounds originated from marine organisms signifies a new wave in the field of drug discovery. Marine organisms produce potent compounds as they hold the phenomenal diversity in chemical structures. The main focus of drug development is anticancer therapy.

METHODS

Expertise on manifold activities of compounds helps in the discovery of their derivatives for preclinical and clinical experiment that promotes improved activity of compounds for cancer patients.

RESULTS

These marine derived compounds stimulate apoptosis in cancer cells by targeting Bcl-2 and Survivin, highlighting the fact that instantaneous targeting of these proteins by novel derivatives results in efficacious and selective killing of cancer cells.

CONCLUSION

Our study reports the identification of Aplysin and Haterumaimide J as Bcl-2 inhibitors and Cortistatin A as an inhibitor of survivin protein, from a sequential virtual screening approach.

Decoding the antineoplastic efficacy of Aplysin targeting Bcl-2: A de novo perspective

The B-cell lymphoma-2 (Bcl-2) family proteins have been attributed to be the key regulators in programmed cell death and apoptosis with a prominent role in human cancer. Understanding the fundamental principles of cell survival and death have been the main cornerstone in cancer drug discovery for identification of novel anticancer agents. In this context the Bcl-2 family of anti-and pro-apoptotic proteins provide an excellent opportunity for development of anticancer agents, as blocking the Bcl-2 or Bcl-XL functionally promotes apoptosis in tumor cells and also sensitize them to chemo- and radiotherapies. The present study reports the identification of novel Aplysin analogs as BCL-2 inhibitors from a sequential virtual screening approach using drug-like, ADMET, docking, pharmacophore filters and molecular dynamics simulation. We identified promising Aplysin analogs that have a potential to be Bcl-2 inhibitors just like the standard drug Obatoclax. One of the compound analog 11 was identified to be a promising inhibitor of Bcl-2 in the docking, pharmacophore and simulation based models.The molecular modeling information provided here can be vital in designing of the novel Bcl-2 inhibitors.

Targeting microRNAs: a new action mechanism of natural compounds

Unlike genetics, epigenetics involves the modification of genome without changes in DNA sequences, including DNA methylation, histone modification, chromatin remodeling and noncoding RNA regulation. MicroRNA (miRNA), a member of noncoding RNAs superfamily, participates in RNA interference through a unique mechanism. Currently, microRNAs have been found to be regulated by some natural compounds. Through altering the expression of miRNAs and influencing the downstream signaling pathways or target genes, several natural compounds exhibit its bioactivity in the prevention, diagnosis, therapy, prognosis and drug resistance of human diseases, such as cancer. In this review, several natural compounds and their studies about miRNA-related action mechanism were summarized. These studies provide a new insight into action mechanism by which natural compound exerts its bioactivity and a novel treatment strategy, demonstrating natural compound a promising remedy for clinical treatments.

Role of MicroRNAs in Malignant Glioma

Objective:

This overview seeked to bring together the microRNA (miRNA) researches on biogenesis and bio-function in these areas of clinical diagnosis and therapy for malignant glioma.

Data Sources:

Using the keyword terms “glioma” and “miRNA,” we performed the literature search in PubMed, Ovid, and web.metstr.com databases from their inception to October 2014.

Study Selection:

In screening out the quality of the articles, factors such as clinical setting of the study, the size of clinical samples were taken into consideration. Animal studied for verification and reviews article were also included in our data collection.

Results:

Despite many advance in miRNA for malignant glioma, further studies were still required to focus on the following aspects: (i) Improving the understanding about biogenesis of miRNA and up-down regulation; (ii) utilizing high-throughput miRNA expression analysis to screen out the core miRNA for glioma; (iii) Focusing related miRNAs on the signal transduction pathways that regulate the proliferation and growth of glioma.

Conclusions:

We discussed the most promising miRNA, correlative signaling pathway and their relation with gliomas in the way of prompting miRNA target into being a clinical therapeutic strategy.

Chemical Diversity and Biological Properties of Secondary Metabolites from Sea Hares of Aplysia Genus

The marine environment is an important source of structurally-diverse and biologically-active secondary metabolites. During the last two decades, thousands of compounds were discovered in marine organisms, several of them having inspired the development of new classes of therapeutic agents. Marine mollusks constitute a successful phyla in the discovery of new marine natural products (MNPs). Over a 50-year period from 1963, 116 genera of mollusks contributed innumerous compounds, Aplysia being the most studied genus by MNP chemists. This genus includes 36 valid species and should be distinguished from all mollusks as it yielded numerous new natural products. Aplysia sea hares are herbivorous mollusks, which have been proven to be a rich source of secondary metabolites, mostly of dietary origin. The majority of secondary metabolites isolated from sea hares of the genus Aplysia are halogenated terpenes; however, these animals are also a source of compounds from other chemical classes, such as macrolides, sterols and alkaloids, often exhibiting cytotoxic, antibacterial, antifungal, antiviral and/or antifeedant activities. This review focuses on the diverse structural classes of secondary metabolites found in Aplysia spp., including several compounds with pronounced biological properties.

MicroRNA-181c inhibits glioblastoma cell invasion, migration and mesenchymal transition by targeting TGF-β pathway

MicroRNAs (miRNAs) are small non-coding RNAs frequently dysregulated in human malignancies. In this study, we found that miR-181c was down-regulated both in glioblastoma tissues and cell lines. We also annotated 566 TCGA miRNA expression profiles and found that patients with high microRNA-181c (miR-181c)-expressing tumors had significantly longer OS and PFS. Overexpression of miR-181c evidently inhibited glioblastoma cell line T98G migration and invasion. Further, the expression of E-cadherin was significantly upregulated and that of N-cadherin and vimentin was significantly down-regulated. We also found that miR-181c overexpression inhibited TGF-β signaling by down-regulating TGFBR1, TGFBR2 and TGFBRAP1 expression. Overall, our study found that miR-181c plays a key role in glioblastoma cell invasion, migration and mesenchymal transition suggesting potential therapeutic applications.