Novel chemical library screen identifies naturally occurring plant products that specifically disrupt glioblastoma-endothelial cell interactions

LC-ESI-MS/MS-based molecular networking, antioxidant, anti-glioma activity and molecular docking studies of Clematis graveolens

Clematis graveolens Lindl., an indigenous climbing plant found in the Himalayan areas, is used by local communities for the treatment of neck tumors. The objective of this work is to examine the comprehensive metabolomic profile, antioxidant capability, in vitro and in silico anti-glioma effects on U-87 human glioma cell lines of the crude extract and fractions from C. graveolens. Liquid chromatography coupled with mass spectroscopy (LC-MS/MS) was used to establish detailed metabolite profiling of C. graveolens. The assessment of cell cytotoxicity was conducted using MTT cell viability assay on U-87 and BHK-21. Through molecular docking studies, the mode of inhibition and binding interaction between identified compounds and target proteins were also determined to evaluate the in vitro results. The use of LC-MS/MS-based global natural products social (GNPS) molecular networking analysis resulted in the identification of 27 compounds. The crude extract, ethyl acetate fraction, and chloroform fraction exhibited significant inhibitory activity against the U-87 cell lines, with IC50 values of 112.0, 138.1, and 142.7 µg/mL, respectively. The ethyl acetate fraction exhibited significant inhibitory concentration for 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity and the metal chelation activity with IC50 value of 39.50 µg/mL, 32.27 µg/mL, and 53.46 µg/mL, respectively. The crude extract showed maximum total phenolic, and total flavonoid concentration measuring 338.7 µg GAE/mg, and 177.04 µg QE/mg, respectively. The findings of this study indicate that C. graveolens consists of a diverse range of active phytoconstituents that possess antioxidant and anti-glioma properties.

Resveratrol as an antitumor agent for glioblastoma multiforme: Targeting resistance and promoting apoptotic cell deaths

Glioblastoma multiforme (GBM) is one of the most aggressive brain and spinal cord tumors. Despite the significant development in application of antitumor drugs, no significant increases have been observed in the survival rates of patients with GBM, as GBM cells acquire resistance to conventional anticancer therapeutic agents. Multiple studies have revealed that PI3K/Akt, MAPK, Nanog, STAT 3, and Wnt signaling pathways are involved in GBM progression and invasion. Besides, biological processes such as anti-apoptosis, autophagy, angiogenesis, and stemness promote GBM malignancy. Resveratrol (RESV) is a non-flavonoid polyphenol with high antitumor activity, the potential of which, regulating signaling pathways involved in cancer malignancy, have been demonstrated by many studies. Herein, we present the potential of RESV in both single and combination therapy- targeting various signaling pathways- which induce apoptotic cell death, re-sensitize cancer cells to radiotherapy, and induce chemo-sensitizing effects to eventually inhibit GBM progression.

Recent updates on the role of phytochemicals in the treatment of glioblastoma multiforme

ABSTRACTS

Glioblastoma multiforme (GBM) is a malignant type of glioma. This malignant brain tumor is a devastating disease and is often fatal. The spectrum of illness and poor prognosis associated with brain tumors extract a terrible toll on patients and their families. The inoperability of these tumors and resistance to radiation and chemotherapy contribute to the fatal outcome of this disease. Thus, scientists are hunting for the new drug candidate and safer chemoprevention, especially the phytochemicals that possess potent anti-tumor properties. We have summarized the cellular and biochemical impacts of different phytochemicals that can successfully encounter GBM via induction of apoptosis and active interference in different cell and molecular pathways associated with GBM in brain tumors. The in silico predictive model determining the blood-brain barrier permeability of the compound and their potential druggability are discussed in the review.

Theoretical and Experimental Investigation of Alginate Microtube Extrusion for Cell Culture Applications

A novel cell culture technology, consisting of hollow alginate tubes, OD ~550 μm, ID ~450μm containing a cell suspension, provides stress-free conditions. Cells reach confluency in approximately ten days with cell densities of 0.5 - 1 billion cells per mL. Tubes are manufactured in a tri-axial needle extruder with three concentric flows. The cell suspension flows in the inner needle (N1), the alginate solution flows in the annulus between N1 and the second needle (N2) and a CaCl ₂ solution is the sheath fluid between the second and third needle (N3). Beyond the tip of N2, the sheath solution is in contact with the alginate and Ca ²⁺ diffuses into the alginate solution and crosslinks it to form an alginate microtube around the core fluid. The cross-linked layer moves radially inwards like a front, starting at the sheath/annulus interface and ends at the annulus/core interface. A mathematical model is used to find the minimum length z _C of direct contact between the CaCl ₂ solution and the alginate solution to complete the cross-linking. Experimental results support the theoretical findings that stable tubes can only be manufactured if the contact length exceeds z _C . Experiments also show that the extruder configuration N3>N2 is best for alginate tube manufacture.

Medicinal Plants for Glioblastoma Treatment

Glioblastoma, an aggressive brain cancer, demonstrates the least life expectancy among all brain cancers. Because of the regulation of diverse signaling pathways in cancers, the chemotherapeutic approaches used to suppress their multiplication and spreading are restricted. Sensitivity towards chemotherapeutic agents has developed because of the pathological and drug-evading abilities of these diverse mechanisms. As a result, the identification and exploration of strategies or treatments, which can overcome such refractory obstacles to improve glioblastoma response to treatment as well as recovery, is essential. Medicinal herbs contain a wide variety of bioactive compounds, which could trigger aggressive brain cancers, regulate their anti-cancer mechanisms and immune responses to assist in cancer elimination, and cause cell death. Numerous tumor-causing proteins, which facilitate invasion as well as metastasis of cancer, tolerance of chemotherapies, and angiogenesis, are also inhibited by these phytochemicals. Such herbs remain valuable for glioblastoma prevention and its incidence by effectively being used as anti-glioma therapies. This review thus presents the latest findings on medicinal plants using which the extracts or bioactive components are being used against glioblastoma, their mechanism of functioning, pharmacological description as well as recent clinical studies conducted on them.

Iridin Induces G2/M Phase Cell Cycle Arrest and Extrinsic Apoptotic Cell Death through PI3K/AKT Signaling Pathway in AGS Gastric Cancer Cells

Iridin is a natural flavonoid found in Belamcanda chinensis documented for its broad spectrum of biological activities like antioxidant, antitumor, and antiproliferative effects. In the present study, we have investigated the antitumor potential of iridin in AGS gastric cancer cells. Iridin treatment decreases AGS cell growth and promotes G2/M phase cell cycle arrest by attenuating the expression of Cdc25C, CDK1, and Cyclin B1 proteins. Iridin-treatment also triggered apoptotic cell death in AGS cells, which was verified by cleaved Caspase-3 (Cl- Caspase-3) and poly ADP-ribose polymerase (PARP) protein expression. Further apoptotic cell death was confirmed by increased apoptotic cell death fraction shown in allophycocyanin (APC)/Annexin V and propidium iodide staining. Iridin also increased the expression of extrinsic apoptotic pathway proteins like Fas, FasL, and cleaved Caspase-8 in AGS cells. On the contrary, iridin-treated AGS cells did not show variations in proteins related to an intrinsic apoptotic pathway such as Bax and Bcl-xL. Besides, Iridin showed inhibition of PI3K/AKT signaling pathways by downregulation of (p-PI3K, p-AKT) proteins in AGS cells. In conclusion, these data suggest that iridin has anticancer potential by inhibiting PI3K/AKT pathway. It could be a basis for further drug design in gastric cancer treatment.

Iridin Prevented Against Lipopolysaccharide-Induced Inflammatory Responses of Macrophages via Inactivation of PKM2-Mediated Glycolytic Pathways

Purpose

Abnormal glycolysis of immune cells contributed to the development of inflammatory response. Inhibition of this Warburg phenotype could be a promising strategy for preventing various inflammatory diseases. Iridin (IRD) is a natural isoflavone, and exerts anticancer, antioxidant, and anti-inflammatory effects. However, the underlying mechanism of IRD on acute inflammation remains unknown. In this study, the protective effects of IRD against lipopolysaccharide (LPS)-induced inflammation were investigated in murine macrophage RAW264.7 cells and in mice.

Methods

The inhibition of IRD on NO production in culture medium was detected by Griess assay while the levels of TNF-α, IL-1β, and MCP-1 were detected by ELISA assay. The effects of IRD on OCR and ECAR levels in LPS-treated macrophages were monitored by using Seahorse Analyzer. The apoptosis rate as well as the release of ROS and NO of RAW264.7 cells were analyzed by flow cytometric assay. The protective effects of IRD were investigated on LPS-induced inflammation in mice. The expressions of PKM2 and its downstream (p-JAK1, p-STAT1, p-STAT3, p-p65, iNOS, and COX2) in cells and in lung tissues were detected by Western blotting analysis.

Results

IRD treatment at the concentrations of 12.5-50 μM significantly inhibited the productions of TNF-α, IL-1β, MCP-1, and ROS, and suppressed the levels of glucose uptake and lactic acid in LPS-treated RAW264.7 cells. Oral administration with IRD (20-80 mg/kg) inhibited LPS-induced acute lung injury as well as inflammatory cytokine production in mice. Moreover, IRD targeted pyruvate kinase isozyme type M2 (PKM2) and suppressed its downstream p-JAK1, p-STAT1, p-STAT3, p-p65, iNOS, and COX2, which could be abolished by PKM2 agonist DASA-58 and antioxidant N-acetyl-L-cysteine, but partly be reversed by NF-κB activator CUT129 and JAK1 activator RO8191.

Conclusion

IRD alleviated LPS-induced inflammation through suppressing PKM2-mediated pathways, and could be a potential candidate for the prevention of inflammatory diseases.

Molecular Targets for Combined Therapeutic Strategies to Limit Glioblastoma Cell Migration and Invasion

The highly invasive nature of glioblastoma imposes poor prospects for patient survival. Molecular evidence indicates glioblastoma cells undergo an intriguing expansion of phenotypic properties to include neuron-like signaling using excitable membrane ion channels and synaptic proteins, augmenting survival and motility. Neurotransmitter receptors, membrane signaling, excitatory receptors, and Ca2+ responses are important candidates for the design of customized treatments for cancers within the heterogeneous central nervous system. Relatively few published studies of glioblastoma multiforme (GBM) have evaluated pharmacological agents targeted to signaling pathways in limiting cancer cell motility. Transcriptomic analyses here identified classes of ion channels, ionotropic receptors, and synaptic proteins that are enriched in human glioblastoma biopsy samples. The pattern of GBM-enriched gene expression points to a major role for glutamate signaling. However, the predominant role of AMPA receptors in fast excitatory signaling throughout the central nervous system raises a challenge on how to target inhibitors selectively to cancer cells while maintaining tolerability. This review critically evaluates a panel of ligand- and voltage-gated ion channels and synaptic proteins upregulated in GBM, and the evidence for their potential roles in the pathological disease progress. Evidence suggests combinations of therapies could be more effective than single agents alone. Natural plant products used in traditional medicines for the treatment of glioblastoma contain flavonoids, terpenoids, polyphenols, epigallocatechin gallate, quinones, and saponins, which might serendipitously include agents that modulate some classes of signaling compounds highlighted in this review. New therapeutic strategies are likely to exploit evidence-based combinations of selected agents, each at a low dose, to create new cancer cell-specific therapeutics.

Natural products: a hope for glioblastoma patients

Glioblastoma (GBM) is one of the most aggressive malignant tumors with an overall dismal survival averaging one year despite multimodality therapeutic interventions including surgery, radiotherapy and concomitant and adjuvant chemotherapy. Few drugs are FDA approved for GBM, and the addition of temozolomide (TMZ) to standard therapy increases the median survival by only 2.5 months. Targeted therapy appeared promising in in vitro monolayer cultures, but disappointed in preclinical and clinical trials, partly due to the poor penetration of drugs through the blood brain barrier (BBB). Cancer stem cells (CSCs) have intrinsic resistance to initial chemoradiation therapy (CRT) and acquire further resistance via deregulation of many signaling pathways. Due to the failure of classical chemotherapies and targeted drugs, research efforts focusing on the use of less toxic agents have increased. Interestingly, multiple natural compounds have shown antitumor and apoptotic effects in TMZ resistant and p53 mutant GBM cell lines and also displayed synergistic effects with TMZ. In this review, we have summarized the current literature on natural products or product analogs used to modulate the BBB permeability, induce cell death, eradicate CSCs and sensitize GBM to CRT.

High content screening of patient-derived cell lines highlights the potential of non-standard chemotherapeutic agents for the treatment of glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most common primary brain malignancy in adults, yet survival outcomes remain poor. First line treatment is well established, however disease invariably recurs and improving prognosis is challenging. With the aim of personalizing therapy at recurrence, we have established a high content screening (HCS) platform to analyze the sensitivity profile of seven patient-derived cancer stem cell lines to 83 FDA-approved chemotherapy drugs, with and without irradiation.

METHODS

Seven cancer stem cell lines were derived from patients with GBM and, along with the established cell line U87-MG, each patient-derived line was cultured in tandem in serum-free conditions as adherent monolayers and three-dimensional neurospheres. Chemotherapeutics were screened at multiple concentrations and cells double-stained to observe their effect on both cell death and proliferation. Sensitivity was classified using high-throughput algorithmic image analysis.

RESULTS

Cell line specific drug responses were observed across the seven patient-derived cell lines. Few agents were seen to have radio-sensitizing effects, yet some drug classes showed a marked difference in efficacy between monolayers and neurospheres. In vivo validation of six drugs suggested that cell death readout in a three-dimensional culture scenario is a more physiologically relevant screening model and could be used effectively to assess the chemosensitivity of patient-derived GBM lines.

CONCLUSION

The study puts forward a number of non-standard chemotherapeutics that could be useful in the treatment of recurrent GBM, namely mitoxantrone, bortezomib and actinomycin D, whilst demonstrating the potential of HCS to be used for personalized treatment based on the chemosensitivity profile of patient tumor cells.

Scalable Culturing of Primary Human Glioblastoma Tumor-Initiating Cells with a Cell-Friendly Culture System

Glioblastoma is the most aggressive and deadly brain cancer. There is growing interest to develop drugs that specifically target to glioblastoma tumor-initiating cells (TICs). However, the cost-effective production of large numbers of high quality glioblastoma TICs for drug discovery with current cell culturing technologies remains very challenging. Here, we report a new method that cultures glioblastoma TICs in microscale alginate hydrogel tubes (or AlgTubes). The AlgTubes allowed long-term culturing (~50 days, 10 passages) of glioblastoma TICs with high growth rate (~700-fold expansion/14 days), high cell viability and high volumetric yield (~3.0 × 10⁸ cells/mL) without losing the stem cell properties, all offered large advancements over current culturing methods. This method can be applied for the scalable production of glioblastoma TICs at affordable cost for drug discovery.

Scalable Production of Glioblastoma Tumor-initiating Cells in 3 Dimension Thermoreversible Hydrogels

There is growing interest in developing drugs that specifically target glioblastoma tumor-initiating cells (TICs). Current cell culture methods, however, cannot cost-effectively produce the large numbers of glioblastoma TICs required for drug discovery and development. In this paper we report a new method that encapsulates patient-derived primary glioblastoma TICs and grows them in 3 dimension thermoreversible hydrogels. Our method allows long-term culture (~50 days, 10 passages tested, accumulative ~>10¹⁰-fold expansion) with both high growth rate (~20-fold expansion/7 days) and high volumetric yield (~2.0 × 10⁷ cells/ml) without the loss of stemness. The scalable method can be used to produce sufficient, affordable glioblastoma TICs for drug discovery.