Expression of p16 and Survivin in gliomas and their correlation with cell proliferation

Multifunctional silica-coated mixed polymeric micelles for integrin-targeted therapy of pediatric patient-derived glioblastoma

Glioblastoma multiforme (GBM) remains a major cause of mortality because treatments are precluded by to the limited transport and penetration of chemotherapeutics across the blood-brain barrier. Pitavastatin (PTV) is a hydrophobic Food and Drug Administration (FDA)-approved anticholesterolemic agent with reported anti-GBM activity. In the present study, we encapsulate PTV in silica-coated polymeric micelles (SiO₂ PMs) surface-modified with the cyclic peptide Arg-Gly-Asp-Phe-Val (cRGDfV) that actively targets the α_vβ₃ integrin overexpressed in the BBB endothelium and GBM. A central composite design is utilized to optimize the preparation process and improve the drug encapsulation ratio from 131 to 780 μg/mL. The silica shell provides full colloidal stability upon extreme dilution and enables a better control of the release kinetics in vitro with 28% of the cargo released after 12 h. Furthermore, SiO₂ PMs show excellent compatibility and are internalized by human BBB endothelial cells, astrocytes and pericytes, as shown by confocal laser scanning fluorescence microscopy and flow cytometry. Finally, the anticancer efficacy is assessed in a pediatric patient-derived glioma cell line expressing high levels of the integrin subunits αv, β3 and β5. This PTV-loaded nanocarrier triggers apoptosis by reducing the mRNA level of anti-apoptotic genes NF-kβ, IL-6, BIRC1 and BIRC5 by 89%, 33%, 81% and 63%, respectively, and the cell viability by >60%. Overall, our results suggest the potential of these hybrid nanocarriers for the targeted therapy of GBM and other tumors overexpressing integrin receptors.

Pivotal Role of STAT3 in Shaping Glioblastoma Immune Microenvironment

Glioblastoma belongs to the most malignant intracranial tumors characterized by indispensable growth and aggressiveness that highly associates with dismal prognosis and therapy resistance. Tumor heterogeneity that often challenges therapeutic schemes is largely attributed to the complex interaction of neoplastic cells with tumor microenvironment (TME). Soluble immunoregulatory molecules secreted by glioma cells attract astrocytes, circulating stem cells and a range of immune cells to TME, inducing a local production of cytokines, chemokines and growth factors that reprogram immune cells to inflammatory phenotypes and manipulate host’s immune response in favor of cancer growth and metastasis. Accumulating evidence indicates that these tolerogenic properties are highly regulated by the constitutive and persistent activation of the oncogenic signal transducer and activator of transcription 3 (STAT3) protein, which impairs anti-tumor immunity and enhances tumor progression. Herein, we discuss current experimental and clinical evidence that highlights the pivotal role of STAT3 in glioma tumorigenesis and particularly in shaping tumor immune microenvironment in an effort to justify the high need of selective targeting for glioma immunotherapy.

The reversal of MRP1 expression induced by low-frequency and low-intensity ultrasound and curcumin mediated by VEGF in brain glioma

Purpose: To explore the effect of curcumin and low-frequency and low-intensity ultrasound (LFLIU) on C6 and U87 cell, and whether LFLIU could inhibit multidrug resistance protein 1 (MRP1) by increasing the sensitivity of curcumin via vascular epithelial growth factor (VEGF)/PI3K/Akt signaling pathway targeting.

Methods: C6 and U87 cells were treated with various doses of curcumin and/or different intensities of LFLIU for 60 s. After 24 hrs, the effects of curcumin and/or LFLIU on the proliferation of C6 and U87 cells were examined. Real-time PCR and western blot analysis were used to detect the expression of VEGF and MRP1 at both mRNA and protein levels. The expression of MRP1 in C6 and U87 cells was also determined following stimulation with recombinant human VEGF and/or LY294002.

Results: Curcumin and LFLIU inhibited the proliferation of glioma cells in an intensity- or dose-dependent manner. Furthermore, survivin was significant after combined treatment compares with that of curcumin or LFLIU treatment alone. VEGF and MRP1 were highly expressed in C6 and U87 cells, curcumin and LFLIU alone or in combination could decrease the expression of both VEGF and MRP1. MRP1 expression was down-regulated following LY294002 treatment, which blocked after exposure to VEGF.

Conclusion: The synergistic effects, such as a higher inhibition rate, and lower expressions of MRP1 and VEGF, of combined curcumin and LFLIU against glioma was much better than that of a single treatment. The down-regulation of MRP1 may be related with the VEGF/PI3K/Akt pathway in glioma.

Evaluation of the use of therapeutic peptides for cancer treatment

Cancer along with cardiovascular disease are the main causes of death in the industrialised countries around the World. Conventional cancer treatments are losing their therapeutic uses due to drug resistance, lack of tumour selectivity and solubility and as such there is a need to develop new therapeutic agents. Therapeutic peptides are a promising and a novel approach to treat many diseases including cancer. They have several advantages over proteins or antibodies: as they are (a) easy to synthesise, (b) have a high target specificity and selectivity and (c) have low toxicity. Therapeutic peptides do have some significant drawbacks related to their stability and short half-life. In this review, strategies used to overcome peptide limitations and to enhance their therapeutic effect will be compared. The use of short cell permeable peptides that interfere and inhibit protein-protein interactions will also be evaluated.

Demethoxycurcumin was superior to temozolomide in the inhibition of the growth of glioblastoma stem cells in vivo

Temozolomide (TMZ) is widely used in the treatment of glioblastoma multiforme (GBM) as it can effectively inhibit the growth of GBM for some months; however, this cancer type is still incurable. The existence of glioma stem cells (GSCs) is thought to be responsible for the invariable recurrence of GBM after treatment, but GSCs are insensitive to TMZ. Our recent research showed that demethoxycurcumin (DMC), a component of curcumin, was superior to TMZ in its ability to inhibit proliferation and induce apoptosis of GSCs in vitro. In addition, the combined treatment of TMZ + DMC induced more obvious anti-GSC effects. However, in this study, no obvious synergistic anti-GSC effects of TMZ + DMC were found in vivo, while DMC was still superior to TMZ with respect to growth inhibition of GSCs in vivo. Furthermore, immunohistochemistry for proliferating cell nuclear antigen (PCNA) showed that such inhibitory effects were mainly related to the inhibition of cell proliferation rather than to apoptosis. However, a high concentration of DMC (50 mg/kg) alone or combined with TMZ could also induce approximately 10 % of the cells to undergo apoptosis according to a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Finally, an investigation of the underlying mechanism revealed that the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) 3 signaling pathway played an important role in the anti-GSC effects. When the JAK inhibitor AG490 was applied, the anti-GSC effects of DMC were enhanced. Taken together, the present work reveals that DMC is superior to TMZ with respect to its anti-GSC effects in vivo, which are mediated through the inhibition of the activation of the JAK/STAT3 pathway; however, DMC demonstrated no synergistic effects with TMZ.