Effects of temozolomide on U87MG glioblastoma cell expression of CXCR4, MMP2, MMP9, VEGF, anti-proliferatory cytotoxic and apoptotic properties

Temozolomide promotes matrix metalloproteinase 9 expression through p38 MAPK and JNK pathways in glioblastoma cells

Glioblastoma (GBM) is a highly aggressive and deadly brain cancer. Temozolomide (TMZ) is the standard chemotherapeutic agent for GBM, but the majority of patients experience recurrence and invasion of tumor cells. We investigated whether TMZ treatment of GBM cells regulates matrix metalloproteinases (MMPs), which have the main function to promote tumor cell invasion. TMZ effectively killed GL261, U343, and U87MG cells at a concentration of 500 µM, and surviving cells upregulated MMP9 expression and its activity but not those of MMP2. TMZ also elevated levels of MMP9 mRNA and MMP9 promoter activity. Subcutaneous graft tumors survived from TMZ treatment also exhibited increased expression of MMP9 and enhanced gelatinolytic activity. TMZ-mediated MMP9 upregulation was specifically mediated through the phosphorylation of p38 and JNK. This then stimulates AP-1 activity through the upregulation of c-Fos and c-Jun. Inhibition of the p38, JNK, or both pathways counteracted the TMZ-induced upregulation of MMP9 and AP-1. This study proposes a potential adverse effect of TMZ treatment for GBM: upregulation of MMP9 expression potentially associated with increased invasion and poor prognosis. This study also provides valuable insights into the molecular mechanisms by which TMZ treatment leads to increased MMP9 expression in GBM cells.

Cellular and Molecular Mechanisms of Mast Cells in Atherosclerotic Plaque Progression and Destabilization

Mast cells (MCs) are commonly recognized for their crucial involvement in the pathogenesis of allergic diseases, but over time, it has come to light that they also play a role in the pathophysiology of non-allergic disorders including atherosclerosis. The involvement of MCs in the pathology of atherosclerosis is supported by their accumulation in atherosclerotic plaques upon their progression and the association of intraplaque MC numbers with acute cardiovascular events. MCs that accumulate within the atherosclerotic plaque release a cocktail of mediators through which they contribute to neovascularization, plaque progression, instability, erosion, rupture, and thrombosis. At a molecular level, MC-released proteases, especially cathepsin G, degrade low-density lipoproteins (LDL) and mediate LDL fusion and binding of LDL to proteoglycans (PGs). Through a complicated network of chemokines including CXCL1, MCs promote the recruitment of among others CXCR2+ neutrophils, therefore, aggravating the inflammation of the plaque environment. Additionally, MCs produce extracellular traps which worsen inflammation and contribute to atherothrombosis. Altogether, evidence suggests that MCs actively, via several underlying mechanisms, contribute to atherosclerotic plaque destabilization and acute cardiovascular syndromes, thus, making the study of interventions to modulate MC activation an interesting target for cardiovascular medicine.

Differences and similarities in biophysical and biological characteristics between U87 MG glioblastoma and astrocyte cells

Current cancer studies focus on molecular-targeting diagnostics and interactions with surroundings; however, there are still gaps in characterization based on topological differences and elemental composition. Glioblastoma (GBM cells; GBMCs) is an astrocytic aggressive brain tumor. At the molecular level, GBMCs and astrocytes may differ, and cell elemental/topological analysis is critical for identifying potential new cancer targets. Here, we used U87 MG cells for GBMCS. U87 MG cell lines, which are frequently used in glioblastoma research, are an important tool for studying the various features and underlying mechanisms of this aggressive brain tumor. For the first time, atomic force microscopy (AFM), scanning electron microscopy (SEM) accompanied by energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) are used to report the topology and chemistry of cancer (U87 MG) and healthy (SVG p12) cells. In addition, F-actin staining and cytoskeleton-based gene expression analyses were performed. The degree of gene expression for genes related to the cytoskeleton was similar; however, the intensity of F-actin, anisotropy values, and invasion-related genes were different. Morphologically, GBMCs were longer and narrower while astrocytes were shorter and more disseminated based on AFM. Furthermore, the roughness values of these cells differed slightly between the two call types. In contrast to the rougher astrocyte surfaces in the lamellipodial area, SEM-EDS analysis showed that elongated GBMCs displayed filopodial protrusions. Our investigation provides considerable further insight into rapid cancer cell characterization in terms of a combinatorial spectroscopic and microscopic approach.

Vascular endothelial growth factor (VEGF) delivery approaches in regenerative medicine

The utilization of growth factors in the process of tissue regeneration has garnered significant interest and has been the subject of extensive research. However, despite the fervent efforts invested in recent clinical trials, a considerable number of these studies have produced outcomes that are deemed unsatisfactory. It is noteworthy that the trials that have yielded the most satisfactory outcomes have exhibited a shared characteristic, namely, the existence of a mechanism for the regulated administration of growth factors. Despite the extensive exploration of drug delivery vehicles and their efficacy in delivering certain growth factors, the development of a reliable predictive approach for the delivery of delicate growth factors like Vascular Endothelial Growth Factor (VEGF) remains elusive. VEGF plays a crucial role in promoting angiogenesis; however, the administration of VEGF demands a meticulous approach as it necessitates precise localization and transportation to a specific target tissue. This process requires prolonged and sustained exposure to a low concentration of VEGF. Inaccurate administration of drugs, either through off-target effects or inadequate delivery, may heighten the risk of adverse reactions and potentially result in tumorigenesis. At present, there is a scarcity of technologies available for the accurate encapsulation of VEGF and its subsequent sustained and controlled release. The objective of this review is to present and assess diverse categories of VEGF administration mechanisms. This paper examines various systems, including polymeric, liposomal, hydrogel, inorganic, polyplexes, and microfluidic, and evaluates the appropriate dosage of VEGF for multiple applications.

Association of angiotensin-converting enzyme (ACE) I/D variation with biochemical parameters and oxidative stress markers in systemic lupus erythematosus patients in west of Iran

PURPOSE

We aimed to study insertion/deletion (I/D) variation (rs4646994) of ACE gene in a group of SLE patients in west of Iran and its possible relationship with oxidative stress.

METHOD AND RESULTS

Genotypes and allele frequencies related to ACE (I/D) variation were determined in 108 SLE patients and 110 gender and age-matched healthy controls using PCR. Neopterin, malondialdehyde (MDA), and serum lipid concentrations were determined by HPLC and enzyme assay respectively. The overall distribution of ACE I/D genotypes in SLE patients was different from that of the control group (P = 0.005). DD genotype compared to ID genotype increased the risk of SLE (OR = 2.57, 95% CI 1.4-4.8, P = 0.003). ID genotype compared to the II genotype decreased the risk of disease (OR = 0.45, 95% CI 0.2-0.99, p = 0.042). SLE patients with DD, ID, and II genotypes had lower paraoxonase (PON) activity and higher serum levels of MDA and neopterin versus control patients. We also detected a significant protective effect against SLE in presence of ACE I alleles and lack of angiotensin II receptor, type 1 (AGTR1) A1166C (NCBI reference SNP id: rs5186), C alleles in this study (OR = 0.31, 95% CI 0.14-0.68, P = 0.002).

CONCLUSIONS

Carriers of the DD genotype of ACE gene with higher serum concentrations of neopterin and MDA, and lower PON activity had a high risk to develop SLE, while ID genotype decreased the risk of disease development by 2.22 times compared to II genotype.

Progesterone and its metabolite allopregnanolone promote invasion of human glioblastoma cells through metalloproteinase‑9 and cSrc kinase

Glioblastomas are the most aggressive and common primary brain tumors in adults. Glioblastoma cells have a great capacity to migrate and invade the brain parenchyma, often reaching the contralateral hemisphere. Progesterone (P4) and its metabolite, allopregnanolone (3α-THP), promote the migration and invasion of human glioblastoma-derived cells. P4 induces migration in glioblastoma cells by the activation of the proto-oncogene tyrosine-protein kinase Src (cSrc) and focal adhesion kinase (Fak). In breast cancer cells, cSrc and Fak promote invasion by increasing the expression and activation of extracellular matrix metalloproteinases (MMPs). However, the mechanism of action by which P4 and 3a-THP promote invasion in glioblastoma cells remains unclear. The effects of P4 and 3α-THP on the protein expression levels of MMP-2 and -9 and the participation of cSrc in progestin effects in U251 and U87 human glioblastoma-derived cells were evaluated. It was determined by western blotting that the P4 increased the protein expression level of MMP-9 in U251 and U87 cells, and 3α-THP increased the protein expression level of MMP-9 in U87 cells. None of these progestins modified MMP-2 protein expression levels. The increase in MMP-9 expression was reduced when the intracellular progesterone receptor and cSrc expression were blocked with small interfering RNAs. Cell invasion induced by P4 and 3α-THP was also blocked by inhibiting cSrc activity with PP2 or by cSrc gene silencing. These results suggest that P4 and its metabolite 3α-THP induce the invasion of glioblastoma cells by increasing MMP-9 expression through the cSrc kinase family. The results of this study provide information of interest in the context of targeted therapies against molecular pathways involved in glioblastoma invasion.

The effect of Azo-dyes on glioblastoma cells in vitro

Despite the multidisciplinary standard treatment of glioblastoma (GB) consisting of maximal surgical resection, followed by radiotherapy (RT) plus concomitant chemotherapy with temozolomide (TMZ), the majority of patients experience tumor progression and almost universal mortality. In recent years, efforts have been made to create new agents for GB treatment, of which azo-dyes proved to be potential candidates, showing antiproliferative effects by inducing apoptosis and by inhibiting different signaling pathways. In this study we evaluated the antiproliferative the effect of six azo-dyes and TMZ on a low passage human GB cell line using MTT assay. We found that all compounds proved antiproliferative properties on GB cells. At equimolar concentrations azo-dyes induced more cytotoxic effect than TMZ. We found that Methyl Orange required the lowest IC₅₀ for 3 days of treatment (26.4684 μM), whilst for 7 days of treatment, two azo dyes proved to have the highest potency: Methyl Orange IC₅₀ = 13.8808 μM and Sudan I IC₅₀ = 12.4829 μM. The highest IC₅₀ was determined for TMZ under both experimental situations. Conclusions: Our research represents a novelty, by offering unique valuable data regarding the azo-dye cyototoxic effects in high grade brain tumors. This study may focus the attention on azo-dye agents that may represent an insufficient exploited source of agents for cancer treatment.

Intracranial In Situ Thermosensitive Hydrogel Delivery of Temozolomide Accomplished by PLGA–PEG–PLGA Triblock Copolymer Blending for GBM Treatment

Glioblastoma (GBM) recurrence after surgical excision has grown to be a formidable obstacle to conquer. In this research, biodegradable thermosensitive triblock copolymer, poly(D, L–lactic acid–co–glycolic acid)–b–poly(ethylene glycol)–b–poly(D, L–lactic acid–co–glycolic acid (PLGA–PEG–PLGA) was utilized as the drug delivery system, loading with micronized temozolomide(micro-TMZ) to form an in situ drug–gel depot inside the resection cavity. The rheology studies revealed the viscoelastic profile of hydrogel under various conditions. To examine the molecular characteristics that affect gelation temperature, ¹H–NMR, inverse gated decoupling ¹³C–NMR, and GPC were utilized. Cryo-SEM and XRD were intended to disclose the appearance of the hydrogel and the micro-TMZ existence state. We worked out how to blend polymers to modify the gelation point (T_gel) and fit the correlation between T_gel and other dependent variables using linear regression. To simulate hydrogel dissolution in cerebrospinal fluid, a membraneless dissolution approach was used. In vitro, micro-TMZ@PLGA–PEG–PLGA hydrogel exhibited Korsmeyer–Peppas and zero–order release kinetics in response to varying drug loading, and in vivo, it suppressed GBM recurrence at an astoundingly high rate. Micro-TMZ@PLGA–PEG–PLGA demonstrates a safer and more effective form of chemotherapy than intraperitoneal TMZ injection, resulting in a spectacular survival rate (40%, n = 10) that is much more than intraperitoneal TMZ injection (22%, n = 9). By proving the viability and efficacy of micro-TMZ@PLGA–PEG–PLGA hydrogel, our research established a novel chemotherapeutic strategy for treating GBM recurrence.

Research progress of anti-glioma chemotherapeutic drugs (Review)

Glioma is the most common primary intracranial malignancy in the central nervous system. At present, the most important treatment option is surgical resection of the tumor combined with radiotherapy and chemotherapy. The principle of operation is to remove the tumor to the maximal extent on the basis of preserving brain function. However, prominent invasive and infiltrative proliferation of glioma tumor cells into the surrounding normal tissues frequently reduces the efficacy of treatment. This in turn worsens the prognosis, because the tumor cannot be completely removed, which can readily relapse. Chemotherapeutic agents when applied individually have demonstrated limited efficacy for the treatment of glioma. However, multiple different chemotherapeutic agents can be used in combination with other treatment modalities to improve the efficacy while circumventing systemic toxicity and drug resistance. Therefore, it is pivotal to unravel the inhibitory mechanism mediated by the different chemotherapeutic drugs on glioma cells in preclinical studies. The aim of the present review is to provide a summary for understanding the effects of different chemotherapeutic drugs in glioma, in addition to providing a reference for the preclinical research into novel chemotherapeutic agents for future clinical application.

Molecular Mechanisms and Clinical Challenges of Glioma Invasion

Glioma is the most common primary brain tumor, and its prognosis is poor. Glioma cells are highly invasive to the brain parenchyma. It is difficult to achieve complete resection due to the nature of the brain tissue, and tumors that invade the parenchyma often recur. The invasiveness of tumor cells has been studied from various aspects, and the related molecular mechanisms are gradually becoming clear. Cell adhesion factors and extracellular matrix factors have a strong influence on glioma invasion. The molecular mechanisms that enhance the invasiveness of glioma stem cells, which have been investigated in recent years, have also been clarified. In addition, it has been discussed from both basic and clinical perspectives that current therapies can alter the invasiveness of tumors, and there is a need to develop therapeutic approaches to glioma invasion in the future. In this review, we will summarize the factors that influence the invasiveness of glioma based on the environment of tumor cells and tissues, and describe the impact of the treatment of glioma on invasion in terms of molecular biology, and the novel therapies for invasion that are currently being developed.

N-2-(phenylamino) benzamide derivatives as novel anti-glioblastoma agents: Synthesis and biological evaluation

Glioblastoma is one of the most lethal brain tumors. The crucial chemotherapy is mainly alkylating agents with modest clinical success. Given this desperate need and inspired by the encouraging results of a phase II trial via concomitant Topo I inhibitor plus COX-2 inhibitor, we designed a series of N-2-(phenylamino) benzamide derivatives as novel anti-glioblastoma agents based on structure modification on 1,5-naphthyridine derivatives (Topo I inhibitors). Notably, the target compounds I-1 (33.61 ± 1.15 μM) and I-8 (45.01 ± 2.37 μM) were confirmed to inhibit COX-2, while a previous reported compound (1,5-naphthyridine derivative) resulted nearly inactive towards COX-2 (IC₅₀ > 150 μM). Besides, I-1 and I-8 exhibited higher anti-proliferation, anti-migration, anti-invasion effects than the parent compound 1,5-naphthyridine derivative, suggesting the success of modification based on the parent. Moreover, I-1 obviously repressed tumor growth in the C6 glioma orthotopic model (TGI = 66.7%) and U87MG xenograft model (TGI = 69.4%). Besides, I-1 downregulated PGE₂, VEGF, MMP-9, and STAT3 activation, upregulated E-cadherin in the orthotopic model. More importantly, I-1 showed higher safety than temozolomide and different mechanism from temozolomide in the C6 glioma orthotopic model. All the evidence demonstrated that N-2-(phenylamino) benzamide derivatives as novel anti-glioblastoma agents could be promising for the glioma management.

Docosahexaenoic acid (DHA) and linoleic acid (LA) modulate the expression of breast cancer involved miRNAs in MDA-MB-231 cell line

BACKGROUND AND AIMS

Docosahexaenoic acid (DHA) and linoleic acid (LA) have modulatory effects on breast cancer (BC) cell lines. We aimed to investigate the effects of DHA, LA alone, in combination, and in the presence of paclitaxel on the expression of five microRNAs involved in the pathology of BC in MDA-MB-231 cell line.

METHODS

MDA-MB-231 cells were treated with either DHA or LA or in combination in the presence/absence of paclitaxel (Taxol). Total RNA was extracted and cDNA synthesized from the cells before and after treatment. The expression levels of miR-30, miR-106b, miR-20, miR-126, and miR-194 were determined by quantitative real-time PCR (qPCR).

RESULTS

Treatment of MDA-MB-231 cells with DHA modulated the gene expression of miR-30 (increased by 7.74-fold (p < 0.0001), miR-194 (decreased by 11-fold (p < 0.0001)), miR-106b (increased by 2.64-fold (p = 0.0004), miR-126 (decreased by 50-fold (p < 0.0001)), and miR-20 (decreased by 4-fold (p < 0.0001)). Additionally, treatment of MDA-MB-231 cells with LA modulated the gene expression of miR-30 (increased by 2.38-fold (p = 0.0001)), miR-194 (decreased by 100-fold (p < 0.0001)), miR-106b (decreased by 10-fold (p < 0.0001)). The combined DHA/LA treatment of MDA-MB-231 cells showed regulatory effect on the expression of studied microRNAs in which decreased the expression of miR-30 (5.5-fold (p < 0.0001)), miR-194 (11-fold (p < 0.0001)), miR-20 (3.5-fold (p = 0.0006)), and increased the expression of miR-106b (9.78-fold (p < 0.0001)).

CONCLUSIONS

Modulation of the expression levels of BC-involved microRNAs could be one of the possible mechanisms of action through which DHA and LA may exert their biologic effects on MDA-MB-231 cell line.

Association of Matrix Metalloproteinase-2 (MMP-2) and MMP-9 Promoter Polymorphisms, Their Serum Levels, and Activities with Coronary Artery Calcification (CAC) in an Iranian Population

The serum levels and activity of matrix metalloproteinases (MMPs) are associated with the risk of coronary artery calcification (CAC). We sought to investigate the association between MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs with MMP-2 and MMP-9 serum levels and activity in individuals with CAC. One hundred and fifty-five cases with CAC and 155 healthy individuals as control group from West of Iran were included and frequency of genotypes and alleles of rs243866 and rs3918242 in MMP-2 and MMP-9 genes were determined using PCR-RFLP. We also investigated the serum levels of MMP-2 and MMP-9 and their activity using ELISA and gelatin zymography, respectively. Additionally, serum biochemical parameters including FBS (fasting blood sugar), urea, creatinine, cholesterol, triglyceride, HDL (high-density lipoprotein), LDL (low-density lipoprotein), calcium, and phosphorus as well as blood pressure (systolic blood pressure (SBP) and diastolic blood pressure (DBP)) were measured. Our results showed that both serum levels of MMP-2 and MMP-9 (P < 0.001) and their activity (P < 0.001) were higher in individuals with CAC when compared to the control group. Carrying A and T alleles in MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs, respectively, may predispose the individuals to CAC by acting as the risk factors. Serum levels and activity of MMP-2 and MMP-9 were found to be higher in CAC cases when compared to the healthy controls. Carriers of A allele in rs243866 SNP and T allele in rs3918242 SNP were shown to have higher MMP-2 and MMP-9 serum levels and activity that may result in increased ECM degradation and support the initiation and development of calcification.

Temozolomide is additive with cytotoxic effect of irradiation in canine glioma cell lines

BACKGROUND

Similar to human glioblastoma patients, glial tumours in dogs have high treatment resistance and a guarded prognosis. In human medicine, the addition of temozolomide to radiotherapy leads to a favourable outcome in vivo as well as a higher antiproliferative effect on tumour cells in vitro.

OBJECTIVES

The aim of the study was to determine the radio- and temozolomide-sensitivity of three canine glial tumour cell lines and to investigate a potential additive cytotoxic effect in combined treatment. Additionally, we wanted to detect the level of MGMT promoter methylation in these cell lines and to investigate a potential association between MGMT promoter methylation and treatment resistance.

METHODS

Cells were treated with various concentrations of temozolomide and/or irradiated with 4 and 8 Gy. Radiosensitization by temozolomide was evaluated using proliferation assay and clonogenic assay, and MGMT DNA methylation was investigated using bisulfite next-generation sequencing.

RESULTS

In all tested canine cell lines, clonogenicity was inhibited significantly in combined treatment compared to radiation alone. All canine glial cell lines tested in this study were found to have high methylation levels of MGMT promoter.

CONCLUSIONS

Hence, an additive effect of combined treatment in MGMT negative canine glial tumour cell lines in vitro was detected. This motivates to further investigate the association between treatment resistance and MGMT, such as MGMT promoter methylation status.

Synergistic Effect of Gefitinib and Temozolomide on U87MG Glioblastoma Angiogenesis

One of the most common and deadly brain tumors is Glioblastoma multiforme (GBM). Due to recent advances in angiogenesis and its related key factors, this process as a hallmark in glioblastoma has attracted more consideration from the research community. Temozolomide (TMZ) as the first-line treatment used to treat GBM but, resistance to TMZ limits its effectiveness and the need for better treatments is still felt. Therefore, we aimed to examine the Synergistic effects of Gefitinib (GFI) in combination with Temozolomide on VEGF and MMPs in glioma cell line (U87MG). Our results displayed that GFI could induce cytotoxic effects in U87MG with IC50 values of 11 μM. U87MG cells produced large amounts of VEGF without any stimuli, and the results showed that GFI in combination with TMZ caused a significant decrease in VEGF production in these cells. In this study, we demonstrated that after treating with TMZ and GFI, there was more decrease in the levels of MMP 2 and 9 secretions in cells than treatment with GFI and TMZ doses alone. This study indicates synergistic effects of GFI plus TMZ against glioma are mediated by the potentiated anti-angiogenesis. Therefore, it can be considered as a promising plan for future studies.

Significance of Mast Cell Formed Extracellular Traps in Microbial Defense

Mast cells (MCs) are critically involved in microbial defense by releasing antimicrobial peptides (such as cathelicidin LL-37 and defensins) and phagocytosis of microbes. In past years, it has become evident that in addition MCs may eliminate invading pathogens by ejection of web-like structures of DNA strands embedded with proteins known together as extracellular traps (ETs). Upon stimulation of resting MCs with various microorganisms, their products (including superantigens and toxins), or synthetic chemicals, MCs become activated and enter into a multistage process that includes disintegration of the nuclear membrane, release of chromatin into the cytoplasm, adhesion of cytoplasmic granules on the emerging DNA web, and ejection of the complex into the extracellular space. This so-called ETosis is often associated with cell death of the producing MC, and the type of stimulus potentially determines the ratio of surviving vs. killed MCs. Comparison of different microorganisms with specific elimination characteristics such as S pyogenes (eliminated by MCs only through extracellular mechanisms), S aureus (removed by phagocytosis), fungi, and parasites has revealed important aspects of MC extracellular trap (MCET) biology. Molecular studies identified that the formation of MCET depends on NADPH oxidase-generated reactive oxygen species (ROS). In this review, we summarize the present state-of-the-art on the biological relevance of MCETosis, and its underlying molecular and cellular mechanisms. We also provide an overview over the techniques used to study the structure and function of MCETs, including electron microscopy and fluorescence microscopy using specific monoclonal antibodies (mAbs) to detect MCET-associated proteins such as tryptase and histones, and cell-impermeant DNA dyes for labeling of extracellular DNA. Comparing the type and biofunction of further MCET decorating proteins with ETs produced by other immune cells may help provide a better insight into MCET biology in the pathogenesis of autoimmune and inflammatory disorders as well as microbial defense.

Mifepristone as a Potential Therapy to Reduce Angiogenesis and P-Glycoprotein Associated With Glioblastoma Resistance to Temozolomide

Glioblastoma, the most common primary central nervous system tumor, is characterized by extensive vascular neoformation and an area of necrosis generated by rapid proliferation. The standard treatment for this type of tumor is surgery followed by chemotherapy based on temozolomide and radiotherapy, resulting in poor patient survival. Glioblastoma is known for strong resistance to treatment, frequent recurrence and rapid progression. The aim of this study was to evaluate whether mifepristone, an antihormonal agent, can enhance the effect of temozolomide on C6 glioma cells orthotopically implanted in Wistar rats. The levels of the vascular endothelial growth factor (VEGF), and P-glycoprotein (P-gp) were examined, the former a promoter of angiogenesis that facilitates proliferation, and the latter an efflux pump transporter linked to drug resistance. After a 3-week treatment, the mifepristone/temozolomide regimen had decreased the level of VEGF and P-gp and significantly reduced tumor proliferation (detected by PET/CT images based on 18F-fluorothymidine uptake). Additionally, mifepristone proved to increase the intracerebral concentration of temozolomide. The lower level of O6-methylguanine-DNA-methyltransferase (MGMT) (related to DNA repair in tumors) previously reported for this combined treatment was herein confirmed. After the mifepristone/temozolomide treatment ended, however, the values of VEGF, P-gp, and MGMT increased and reached control levels by 14 weeks post-treatment. There was also tumor recurrence, as occurred when administering temozolomide alone. On the other hand, temozolomide led to 100% mortality within 26 days after beginning the drug treatment, while mifepristone/temozolomide enabled 70% survival 60–70 days and 30% survived over 100 days, suggesting that mifepristone could possibly act as a chemo-sensitizing agent for temozolomide.