Curcumin-induced cell death depends on the level of autophagic flux in A172 and U87MG human glioblastoma cells

Potential of Natural Products in the Treatment of Glioma: Focus on Molecular Mechanisms

Despite the waning of traditional treatments for glioma due to possible long-term issues, the healing possibilities of substances derived from nature have been reignited in the scientific community. These natural substances, commonly found in fruits and vegetables, are considered potential alternatives to pharmaceuticals, as they have been shown in prior research to impact pathways surrounding cancer progression, metastases, invasion, and resistance. This review will explore the supposed molecular mechanisms of different natural components, such as berberine, curcumin, coffee, resveratrol, epigallocatechin-3-gallate, quercetin, tanshinone, silymarin, coumarin, and lycopene, concerning glioma treatment. While the benefits of a balanced diet containing these compounds are widely recognized, there is considerable scope for investigating the efficacy of these natural products in treating glioma.

Phytochemical-mediated modulation of autophagy and endoplasmic reticulum stress as a cancer therapeutic approach

Autophagy and endoplasmic reticulum (ER) stress are conserved processes that generally promote survival, but can induce cell death when physiological thresholds are crossed. The pro-survival aspects of these processes are exploited by cancer cells for tumor development and progression. Therefore, anticancer drugs targeting autophagy or ER stress to induce cell death and/or block the pro-survival aspects are being investigated extensively. Consistently, several phytochemicals have been reported to exert their anticancer effects by modulating autophagy and/or ER stress. Various phytochemicals (e.g., celastrol, curcumin, emodin, resveratrol, among others) activate the unfolded protein response to induce ER stress-mediated apoptosis through different pathways. Similarly, various phytochemicals induce autophagy through different mechanisms (namely mechanistic target of Rapamycin [mTOR] inhibition). However, phytochemical-induced autophagy can function either as a cytoprotective mechanism or as programmed cell death type II. Interestingly, at times, the same phytochemical (e.g., 6-gingerol, emodin, shikonin, among others) can induce cytoprotective autophagy or programmed cell death type II depending on cellular contexts, such as cancer type. Although there is well-documented mechanistic interplay between autophagy and ER stress, only a one-way modulation was noted with some phytochemicals (carnosol, capsaicin, cryptotanshinone, guangsangon E, kaempferol, and δ-tocotrienol): ER stress-dependent autophagy. Plant extracts are sources of potent phytochemicals and while numerous phytochemicals have been investigated in preclinical and clinical studies, the search for novel phytochemicals with anticancer effects is ongoing from plant extracts used in traditional medicine (e.g., Origanum majorana). Nonetheless, the clinical translation of phytochemicals, a promising avenue for cancer therapeutics, is hindered by several limitations that need to be addressed in future studies.

Review on the Therapeutic Potential of Curcumin and its Derivatives on Glioma Biology

Gliomas are common and aggressive brain tumors that carry a poor prognosis. The current multimodal therapeutic option for glioma includes surgery subsequently temozolomide chemotherapy and/or radiation; but gliomas are often associated with multidrug resistance, intensive adverse events, and tumor relapse. Thus, novel interventions that can enhance successful chemo-prevention and overcome therapeutic resistance are urgently needed. Phytochemicals have several biological properties with multi-target sites and relatively limited degrees of toxicity. Curcumin is a natural polyphenolic compound with several anti-tumor effects which potentially inhibit tumor growth, development, proliferation, invasion, dissemination, and angiogenesis in different human malignancies. Experimental model studies have demonstrated that curcumin attenuates glioma cell viability by G2/M cell cycle arrest, apoptosis, induction of autophagy, gene expression alteration, and disruption of multi-molecular pathways. Moreover, curcumin has been reported to re-sensitize cancer to chemotherapeutics as well as augment the effect of radiotherapy on glioma cells. In this review, we have provided an update on the in vitro and in vivo effects of curcumin-based therapy on gliomas. We have also discussed the use of curcumin in combination therapies, its effectiveness on drug-resistant cells, and new formulations of curcumin in the treatment of gliomas.

B Cell Adhesion to Fibroblast-Like Synoviocytes Is Up-Regulated by Tumor Necrosis Factor-Alpha via Expression of Human Vascular Cell Adhesion Molecule-1 Mediated by B Cell-Activating Factor

Fibroblast-like synoviocytes (FLSs) play a key role in the pathogenesis of rheumatoid arthritis (RA) by producing inflammatory cytokines and interacting with various immune cells, which contribute to cartilage destruction. RA-FLSs activated by tumor necrosis factor alpha (TNF-α), exacerbate joint damage by triggering the expression of various inflammatory molecules, including human vascular cell adhesion molecule-1 (hVCAM1) and B cell-activating factor (hBAFF), with a role in maturation and maintenance of B cells. Here, we investigated whether B cell interaction with FLSs could be associated with hVCAM1 expression by TNF-α through hBAFF, using WiL2-NS B cells and MH7A synovial cells. TNF-α enhanced the expression of hVCAM1 and hBAFF. B cell adhesion to FLSs was increased by treatment with TNF-α or hBAFF protein. hVCAM expression was up-regulated by transcriptional activation of the hVCAM1 promoter(−1549 to −54) in MH7A cells treated with hBAFF protein or overexpressed with hBAFF gene. In contrast, hVCAM1 expression was down-regulated by treatment with hBAFF-siRNA. JNK was activated by TNF-α treatment. Then, hVCAM1 expression and B cell adhesion to FLSs were reduced by the treatment with JNK inhibitor SP600125. Transcriptional activity of hVCAM1 by the stimulation with TNF-α was inhibited by the deletion of −1549 to −229 from the hVCAM1 promoter. hVCAM1 expression and B cell adhesion to FLSs were reduced by treatment with hVCAM1-siRNA. Taken together, these results suggest that B cell adhesion to FLSs is associated with TNF-α-induced up-regulation of hVCAM1 expression via hBAFF expression. Thus, the pathological progression of RA may be associated with hVCAM1-mediated interaction of synovial cells with B lymphocytes.

Chemical diversity of dietary phytochemicals and their mode of chemoprevention

Despite the advancement in prognosis, diagnosis and treatment, cancer has emerged as the second leading cause of disease-associated death across the globe. With the remarkable application of synthetic drugs in cancer therapy and the onset of therapy-associated adverse effects, dietary phytochemicals have been materialized as potent anti-cancer drugs owing to their antioxidant, apoptosis and autophagy modulating activities. With dynamic regulation of apoptosis and autophagy in association with cell cycle regulation, inhibition in cellular proliferation, invasion and migration, dietary phytochemicals have emerged as potent anti-cancer pharmacophores. Dietary phytochemicals or their synthetic analogous as individual drug candidates or in combination with FDA approved chemotherapeutic drugs have exhibited potent anti-cancer efficacy. With the advancement in cancer therapeutics, dietary phytochemicals hold high prevalence for their use as precision and personalized medicine to replace conventional chemotherapeutic drugs. Hence, keeping these perspectives in mind, this review focuses on the diversity of dietary phytochemicals and their molecular mechanism of action in several cancer subtypes and tumor entities. Understanding the possible molecular key players involved, the use of dietary phytochemicals will thrive a new horizon in cancer therapy.

The Paired Siglecs in Brain Tumours Therapy: The Immunomodulatory Effect of Dexamethasone and Temozolomide in Human Glioma In Vitro Model

The paired sialic acid-binding immunoglobulin like lectins (Siglecs) are characterized by similar cellular distribution and ligand recognition but opposing signalling functions attributed to different intracellular sequences. Since sialic acid—Siglec axis are known to control immune homeostasis, the imbalance between activatory and inhibitory mechanisms of glycan-dependent immune control is considered to promote pathology. The role of sialylation in cancer is described, however, its importance in immune regulation in gliomas is not fully understood. The experimental and clinical observation suggest that dexamethasone (Dex) and temozolomide (TMZ), used in the glioma management, alter the immunity within the tumour microenvironment. Using glioma-microglia/monocytes transwell co-cultures, we investigated modulatory action of Dex/TMZ on paired Siglecs. Based on real-time PCR and flow cytometry, we found changes in SIGLEC genes and their products. These effects were accompanied by altered cytokine profile and immune cells phenotype switching measured by arginases expression. Additionally, the exposure to Dex or TMZ increased the binding of inhibitory Siglec-5 and Siglec-11 fusion proteins to glioma cells. Our study suggests that the therapy-induced modulation of the interplay between sialoglycans and paired Siglecs, dependently on patient’s phenotype, is of particular signification in the immune surveillance in the glioma management and may be useful in glioma patient’s therapy plan verification.

Toward Regulatory Effects of Curcumin on Transforming Growth Factor-Beta Across Different Diseases: A Review

Immune response, proliferation, migration and angiogenesis are juts a few of cellular events that are regulated by transforming growth factor-β (TGF-β) in cells. A number of studies have documented that TGF-β undergoes abnormal expression in different diseases, e.g., diabetes, cancer, fibrosis, asthma, arthritis, among others. This has led to great fascination into this signaling pathway and developing agents with modulatory impact on TGF-β. Curcumin, a natural-based compound, is obtained from rhizome and roots of turmeric plant. It has a number of pharmacological activities including antioxidant, anti-inflammatory, anti-tumor, anti-diabetes and so on. Noteworthy, it has been demonstrated that curcumin affects different molecular signaling pathways such as Wnt/β-catenin, Nrf2, AMPK, mitogen-activated protein kinase and so on. In the present review, we evaluate the potential of curcumin in regulation of TGF-β signaling pathway to corelate it with therapeutic impacts of curcumin. By modulation of TGF-β (both upregulation and down-regulation), curcumin ameliorates fibrosis, neurological disorders, liver disease, diabetes and asthma. Besides, curcumin targets TGF-β signaling pathway which is capable of suppressing proliferation of tumor cells and invading cancer cells.