Mechanistic Study of Tetrahydrofuran- acetogenins In Triggering Endoplasmic Reticulum Stress Response-apotoposis in Human Nasopharyngeal Carcinoma

Synthesis of carbohydrate analogues of the THF-acetogenin 4-deoxyannomontacin and their cytotoxicity against human prostate cancer cell lines

The THF containing acetogenin 4-deoxyannonmontacin (4-DAN) has attracted interest for its potent cytotoxicity against a broad range of human tumor cell lines, and relatively simple structure. Herein is described the synthesis and cytotoxicity of C-10 epimers of 4-DAN and analogues thereof comprising carbohydrate and thiophene substitutes for the THF and butenolide moieties respectively. The key synthetic ploy was the union of THF and butenolide segments or their substitutes, via an alkene cross metathesis. The different analogues showed cytotoxicity in the low micromolar to nanomolar range against the human prostate cancer cell lines LNCaP and PC3. A relatively simple mannose-linked thiophene analog was found to be similar in activity to 4-DAN.

Alkaloid and acetogenin-rich fraction from Annona crassiflora fruit peel inhibits proliferation and migration of human liver cancer HepG2 cells

Plant species from Annonaceae are commonly used in traditional medicine to treat various cancer types. This study aimed to investigate the antiproliferative potential of an alkaloid and acetogenin-rich fraction from the fruit peel of Annona crassiflora in HepG2 cells. A liquid-liquid fractionation was carried out on the ethanol extract of A. crassiflora fruit peel in order to obtain an alkaloid and acetogenin-rich fraction (AF-Ac). Cytotoxicity, proliferation and migration were evaluated in the HepG2 cells, as well as the proliferating cell nuclear antigen (PCNA), vinculin and epidermal growth factor receptor (EGFR) expression. In addition, intracellular Ca2+ was determined using Fluo4-AM and fluorescence microscopy. First, 9 aporphine alkaloids and 4 acetogenins that had not yet been identified in the fruit peel of A. crassiflora were found in AF-Ac. The treatment with 50 μg/mL AF-Ac reduced HepG2 cell viability, proliferation and migration (p < 0.001), which is in accordance with the reduced expression of PCNA and EGFR levels (p < 0.05). Furthermore, AF-Ac increased intracellular Ca2+ in the HepG2 cells, mobilizing intracellular calcium stores, which might be involved in the anti-migration and anti-proliferation capacities of AF-Ac. Our results support the growth-inhibitory potential of AF-Ac on HepG2 cells and suggest that this effect is triggered, at least in part, by PCNA and EGFR modulation and mobilization of intracellular Ca2+. This study showed biological activities not yet described for A. crassiflora fruit peel, which provide new possibilities for further in vivo studies to assess the antitumoral potential of A. crassiflora, especially its fruit peel.

Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study

Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.

Synthesis and Cytotoxic Property of Annonaceous Acetogenin Glycoconjugates

Background

Annonaceous acetogenins (ACGs) are secondary metabolites produced by the Annonaceae family and display potent anticancer activity against various cancer cell lines. Squamocin and bullatacin are two examples of ACGs that show promising antitumor activity; however, preclinical data are not sufficient partly due to their being highly lipophilic and poorly soluble in water. These compounds also display high toxicity to normal cells. Due to these disadvantageous properties, the therapeutic potential of squamocin and bullatacin as antitumor agents has not been fully evaluated.

Methods

In order to enhance their water solubility and potentially improve their cancer targeting, squamocin and bullatacin were conjugated to a glucose or galactose to yield glycosylated derivatives by direct glycosylation or the Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reaction (the click reaction). The synthesized compounds were evaluated for their anticancer property against HeLa, A549 and HepG2 cancer cell lines using MTT assay.

Results

Nine glycosyl derivatives were synthesized and structurally characterized. Most of them show comparable in vitro cytotoxicity against HeLa, A549 and HepG2 cancer cell lines as their parent compounds squamocin and bullatacin. It appears that the type of sugar residue (glucose or galactose), the position at which the sugar residue is attached, and whether or not a linking spacer is present do not affect the potency of these derivatives much. The solubility of galactosylated squamocin 13 in phosphate buffer saline (PBS, pH = 7) is greatly improved (1.37 mg/mL) in comparison to squamocin (not detected in PBS).

Conclusion

The conjugation of a glucose or galactose to squamocin and bullatacin yields glycosyl derivatives with similar level of anticancer activity in tested cell lines. Further studies are needed to demonstrate whether or not these compounds show reduced toxicity to normal cells and their therapeutic potential as antitumor agents.

An Overview of Saturated Cyclic Ethers: Biological Profiles and Synthetic Strategies

Saturated oxygen heterocycles are widely found in a broad array of natural products and other biologically active molecules. In medicinal chemistry, small and medium rings are also important synthetic intermediates since they can undergo ring-opening and -expansion reactions. These applications have driven numerous studies on the synthesis of oxygen-containing heterocycles and considerable effort has been devoted toward the development of methods for the construction of saturated oxygen heterocycles. This paper provides an overview of the biological roles and synthetic strategies of saturated cyclic ethers, covering some of the most studied and newly discovered related natural products in recent years. This paper also reports several promising and newly developed synthetic methods, emphasizing 3-7 membered rings.

Targeting the unfolded protein response in head and neck and oral cavity cancers

Many FDA-approved anti-cancer therapies, targeted toward a wide array of molecular targets and signaling networks, have been demonstrated to activate the unfolded protein response (UPR). Despite a critical role for UPR signaling in the apoptotic execution of cancer cells by many of these compounds, the authors are currently unaware of any instance whereby a cancer drug was developed with the UPR as the intended target. With the essential role of the UPR as a driving force in the genesis and maintenance of the malignant phenotype, a great number of pre-clinical studies have surged into the medical literature describing the ability of dozens of compounds to induce UPR signaling in a myriad of cancer models. The focus of the current work is to review the literature and explore the role of the UPR as a mediator of chemotherapy-induced cell death in squamous cell carcinomas of the head and neck (HNSCC) and oral cavity (OCSCC), with an emphasis on preclinical studies.