Effects of the Anti-Tumorigenic Agent AT101 on Human Glioblastoma Cells in the Microenvironmental Glioma Stem Cell Niche

Glioblastoma (GBM) is a barely treatable disease due to its profound chemoresistance. A distinct inter- and intratumoral heterogeneity reflected by specialized microenvironmental niches and different tumor cell subpopulations allows GBMs to evade therapy regimens. Thus, there is an urgent need to develop alternative treatment strategies. A promising candidate for the treatment of GBMs is AT101, the R(-) enantiomer of gossypol. The present study evaluates the effects of AT101, alone or in combination with temozolomide (TMZ), in a microenvironmental glioma stem cell niche model of two GBM cell lines (U251MG and U87MG). AT101 was found to induce strong cytotoxic effects on U251MG and U87MG stem-like cells in comparison to the respective native cells. Moreover, a higher sensitivity against treatment with AT101 was observed upon incubation of native cells with a stem-like cell-conditioned medium. This higher sensitivity was reflected by a specific inhibitory influence on the p-p42/44 signaling pathway. Further, the expression of CXCR7 and the interleukin-6 receptor was significantly regulated upon these stimulatory conditions. Since tumor stem-like cells are known to mediate the development of tumor recurrences and were observed to strongly respond to the AT101 treatment, this might represent a promising approach to prevent the development of GBM recurrences.     

Polyunsaturated Fatty Acid-Enriched Lipid Fingerprint of Glioblastoma Proliferative Regions Is Differentially Regulated According to Glioblastoma Molecular Subtype

Glioblastoma (GBM) represents one of the deadliest tumors owing to a lack of effective treatments. The adverse outcomes are worsened by high rates of treatment discontinuation, caused by the severe side effects of temozolomide (TMZ), the reference treatment. Therefore, understanding TMZ’s effects on GBM and healthy brain tissue could reveal new approaches to address chemotherapy side effects. In this context, we have previously demonstrated the membrane lipidome is highly cell type-specific and very sensitive to pathophysiological states. However, little remains known as to how membrane lipids participate in GBM onset and progression. Hence, we employed an ex vivo model to assess the impact of TMZ treatment on healthy and GBM lipidome, which was established through imaging mass spectrometry techniques. This approach revealed that bioactive lipid metabolic hubs (phosphatidylinositol and phosphatidylethanolamine plasmalogen species) were altered in healthy brain tissue treated with TMZ. To better understand these changes, we interrogated RNA expression and DNA methylation datasets of the Cancer Genome Atlas database. The results enabled GBM subtypes and patient survival to be linked with the expression of enzymes accounting for the observed lipidome, thus proving that exploring the lipid changes could reveal promising therapeutic approaches for GBM, and ways to ameliorate TMZ side effects.     

Synergistic inhibition of human glioma cell line by temozolomide and PAMAM‐mediated miR‐21i

Temozolomide (TMZ) is a promising chemotherapeutic agent for treating glioblastomas. However, resistance develops quickly and with a high frequency. Efforts to overcome chemoresistance are, therefore, critically needed. In present study, a poly(amidoamine; PAMAM) dendrimer was used as a vector to deliver microRNA‐21 inhibitor (miR‐21i) into U87 cells and the chemosensitivity of the combination effect of miR‐21i and TMZ for glioma therapy was investigated. Flow cytometry analysis showed the uptake efficiency of microRNA‐21 inhibitor after complexation with PAMAM. Real‐time PCR and in situ hybridization indicated that, compared with TMZ or miR‐21i treated cells, cells simultaneously treated with miR‐21i and TMZ showed a remarkable decrease in the microRNA‐21 (miR‐21) level. The transfection of miR‐21i enhanced the chemosensitivity by significantly decreasing the IC50 value of TMZ to glioma cells. Knockdown of miR‐21 promoted the cells' apoptosis, and at the same time, inhibited cell invasion. In conclusion, the combination treatment of glioma cells with TMZ and miR‐21i could yield a synergistic effect in inhibition of human glioma cell line. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Prolonged drug release using PCL–TMZ nanofibers induce the apoptotic behavior of U87 glioma cells

In situ prolonged delivery of drugs at the site of tumor can be satisfactorily accelerated patient recovery. We compared the effect of temozolomide while incorporated by polycaprolactone nanofibers on the apoptotic behavior of U87 glioma cells. After biocompatibility evaluation of nanofibers by scanning electron microscope and 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide analysis, the apoptosis of U87 cells was evaluated using p53, Bcl2 and Bax genes expression. It was found that nanofiber-temozolomide group showed a greater ability to induce apoptosis as well as have a significantly diminished initial burst release of drug compared with other groups and have promising potential in treating cancer.     

Traceable Nanoparticles with Dual Targeting and ROS Response for RNAi‐Based Immunochemotherapy of Intracranial Glioblastoma Treatment

The chemotherapy of glioblastoma is severely hindered by the immunosuppressive tumor microenvironment, especially the tumor growth factor β (TGF‐β), an immunosuppressive cytokine. In this study, it is proposed to employ RNAi‐based immunomodulation to modify the tumor immune microenvironment and improve the effect of chemotherapy. Herein, a nanotheranostic system (Angiopep LipoPCB(Temozolomide+BAP/siTGF‐β), ALBTA) with dual targeting and ROS response is established for intracranial glioblastoma treatment. The traceable nanoparticles exhibit strong siRNA condensation, high drug loading efficiency, good serum stability, and magnetic property. They can efficiently cross the blood–brain barrier and target to glioblastoma cells via receptor‐mediated transcytosis. The zwitterionic lipid (distearoyl phosphoethanol‐amine‐polycarboxybetaine lipid) in ALBTA promotes endosomal/lysosomal escape, and thus enhances the cytotoxicity of temozolomide and improves gene silencing efficiency of siTGF‐β. ALBTA significantly improves the immunosuppressive microenvironment and prolongs the survival time of glioma‐bearing mice. Moreover, ALBTA can be accurately traced by MRI in brain tumors. The study indicates that this immunochemotherapeutic platform can serve as a flexible and powerful synergistic system for treatment with brain tumors as well as other brain diseases in central nervous system.     

Effects of Long-Term Temozolomide Treatment on Glioblastoma and Astrocytoma WHO Grade 4 Stem-like Cells

Glioblastoma leads to a fatal course within two years in more than two thirds of patients. An essential cornerstone of therapy is chemotherapy with temozolomide (TMZ). The effect of TMZ is counteracted by the cellular repair enzyme O⁶-methylguanine-DNA methyltransferase (MGMT). The MGMT promoter methylation, the main regulator of MGMT expression, can change from primary tumor to recurrence, and TMZ may play a significant role in this process. To identify the potential mechanisms involved, three primary stem-like cell lines (one astrocytoma with the mutation of the isocitrate dehydrogenase (IDH), CNS WHO grade 4 (HGA)), and two glioblastoma (IDH-wildtype, CNS WHO grade 4) were treated with TMZ. The MGMT promoter methylation, migration, proliferation, and TMZ-response of the tumor cells were examined at different time points. The strong effects of TMZ treatment on the MGMT methylated cells were observed. Furthermore, TMZ led to a loss of the MGMT promoter hypermethylation and induced migratory rather than proliferative behavior. Cells with the unmethylated MGMT promoter showed more aggressive behavior after treatment, while HGA cells reacted heterogenously. Our study provides further evidence to consider the potential adverse effects of TMZ chemotherapy and a rationale for investigating potential relationships between TMZ treatment and change in the MGMT promoter methylation during relapse.     

替莫唑胺联合利妥昔单抗对复发的老年原发中枢神经淋巴瘤的应用

Objective: The aim of our study was to analyze the long-term results of rituximab combined with temozolomide in treatment of elderly patients (> 60 years) with relapsed primary central nervous system lymphoma (PCNSL). Methods:Twelve postoperative elderly patients (> 60 years) were treated between August 2004 and October 2009. Temozolomide 100 mg/m2 to 200 mg/m2 days 1 to 7 and 15 to 21 and rituximab 375 mg/m2 days 1, 5, 8, 22. The maximum number of rituximab cycles was two. After one or two cycles of this combination, patients with an objective response and an acceptable level of toxicity continued treatment with single agent temozolomide (days 1 to 5, every 28 days). The overall survival was analyzed by using Kaplan-Meier. Results: The overall survival was 9 months. Toxicity was very mild with no grade 3-4 neurotoxicity toxic events. Conclusion: Rituximab combined with temozolomide seems to yields substantial long-term survival with moderate toxicity for the treatment of elderly relapsed PCNSL.     

TRPML2 Mucolipin Channels Drive the Response of Glioma Stem Cells to Temozolomide and Affect the Overall Survival in Glioblastoma Patients

The survival of patients with glioblastoma (GBM) is poor. The main cause is the presence of glioma stem cells (GSCs), exceptionally resistant to temozolomide (TMZ) treatment. This last may be related to the heterogeneous expression of ion channels, among them TRPML2. Its mRNA expression was evaluated in two different neural stem cell (NS/PC) lines and sixteen GBM stem-like cells by qRT-PCR. The response to TMZ was evaluated in undifferentiated or differentiated GSCs, and in TRPML2-induced or silenced GSCs. The relationship between TRPML2 expression and responsiveness to TMZ treatment was evaluated by MTT assay showing that increased TRPML2 mRNA levels are associated with resistance to TMZ. This research was deepened by qRT-PCR and western blot analysis. PI3K/AKT and JAK/STAT pathways as well as ABC and SLC drug transporters were involved. Finally, the relationship between TRPML2 expression and overall survival (OS) and progression-free survival (PFS) in patient-derived GSCs was evaluated by Kaplan–Meier analysis. The expression of TRPML2 mRNA correlates with worse OS and PFS in GBM patients. Thus, the expression of TRPML2 in GSCs influences the responsiveness to TMZ in vitro and affects OS and PFS in GBM patients.     

15例垂体巨大腺瘤患者调强放射治疗效果分析

目的分析调强放射治疗技术治疗垂体巨大腺瘤的临床实践经验,以期为临床诊疗提供借鉴。方法回顾性分析2012年10月至2018年10月于北京协和医院放射治疗科接受直线加速器6 MV-X线调强放射治疗(56～60 Gy/28～30次,5次/周)的垂体巨大腺瘤患者资料,以肿瘤生长控制率、激素缓解率、放射治疗相关并发症为指标评价患者的治疗效果。结果共15例符合纳入标准的患者入选本研究,其中男性8例,女性7例;中位年龄为32岁。肿瘤生长控制率为93.3%(11例部分缓解,3例肿瘤稳定,1例发展为垂体癌);7例功能性垂体巨大腺瘤患者中,1例激素水平完全缓解,2例部分缓解。4例患者采用调强放射治疗联合替莫唑胺治疗,均达到肿瘤部分缓解(中位缓解时间为5个月),缓解率及缓解时间均优于未使用替莫唑胺者。放射治疗后随访期内,4例患者出现新发垂体功能受损,未出现新发或进一步加重的视力减退及视野受损。结论调强放射治疗是垂体巨大腺瘤患者有效的治疗方法,与替莫唑胺联合应用可加快肿瘤体积缩小、缓解占位效应。