USP19 regulates DNA methylation damage repair and confers temozolomide resistance through MGMT stabilization.

OBJECTIVE: To elucidate the relationship between USP19 and O(6)-methylguanine-DNA methyltransferase (MGMT) after temozolomide treatment in glioblastoma (GBM) patients with chemotherapy resistance. METHODS: Screening the deubiquitinase pannel and identifying the deubiquitinase directly interacts with and deubiquitination MGMT. Deubiquitination assay to confirm USP19 deubiquitinates MGMT. The colony formation and tumor growth study in xenograft assess USP19 affects the GBM sensitive to TMZ was performed by T98G, LN18, U251, and U87 cell lines. Immunohistochemistry staining and survival analysis were performed to explore how USP19 is correlated to MGMT in GBM clinical management. RESULTS: USP19 removes the ubiquitination of MGMT to facilitate the DNA methylation damage repair. Depletion of USP19 results in the glioblastoma cell sensitivity to temozolomide, which can be rescued by overexpressing MGMT. USP19 is overexpressed in glioblastoma patient samples, which positively correlates with the level of MGMT protein and poor prognosis in these patients. CONCLUSION: The regulation of MGMT ubiquitination by USP19 plays a critical role in DNA methylation damage repair and GBM patients' temozolomide chemotherapy response.

Polymer-Drug Conjugates Codeliver a Temozolomide Intermediate and Nitric Oxide for Enhanced Chemotherapy against Glioblastoma Multiforme.

Polymer-drug conjugates (PDCs) provide possibilities for the development of multiresponsive drug delivery and release platforms utilized in cancer therapy. The delivery of Temozolomide (TMZ, a DNA methylation agent) by PDCs has been developed to improve TMZ stability under physiological conditions for the treatment of glioblastoma multiforme (GBM); however, with inefficient chemotherapeutic efficacy. In this work, we synthesized an amphiphilic triblock copolymer (P1-SNO) with four pendant functionalities, including (1) a TMZ intermediate (named MTIC) as a prodrug moiety, (2) a disulfide bond as a redox-responsive trigger to cage MTIC, (3) S-nitrosothiol as a light/heat-responsive donor of nitric oxide (NO), and (4) a poly(ethylene glycol) chain to enable self-assembly in aqueous media. P1-SNO was demonstrated to liberate MTIC in the presence of reduced glutathione and release gaseous NO upon exposure to light or heat. The in vitro results revealed a synergistic effect of released MTIC and NO on both TMZ-sensitive and TMZ-resistant GBM cells. The environment-responsive PDC system for codelivery of MTIC and NO is promising to overcome the efficacy issue in TMZ-based cancer therapy.

Rise of oligodendroglioma hypermutator phenotype from a subclone harboring TP53 mutation after TMZ treatment.

Oligodendrogliomas characterized and defined by 1p/19q co-deletion are slowly growing tumors showing better prognosis than astrocytomas. TP53 mutation is rare in oligodendrogliomas while the vast majority of astrocytomas harbor the mutation, making TP53 mutation mutually exclusive with 1p/19q codeletion in lower grade gliomas virtually. We report a case of 51-year-old woman with a left fronto-temporal oligodendroglioma that contained a small portion with a TP53 mutation, R248Q, at the initial surgery. On a first, slow-growing recurrence 29 months after radiation and nitrosourea-based chemotherapy, the patient underwent TMZ chemotherapy. The recurrent tumor responded well to TMZ but developed a rapid progression after 6 cycles as a malignant hypermutator tumor with a MSH6 mutation. Most of the recurrent tumor lacked typical oligodendroglioma morphology that was observed in the primary tumor, while it retained the IDH1 mutation and 1p/19q co-deletion. The identical TP53 mutation observed in the small portion of the primary tumor was universal in the recurrence. This case embodied the theoretically understandable clonal expansion of the TP53 mutation with additional mismatch repair gene dysfunction leading to hypermutator phenotype. It thus indicated that TP53 mutation in oligodendroglioma, although not common, may play a critical role in the development of hypermutator after TMZ treatment.

Tumor microenvironment targeting for glioblastoma multiforme treatment via hybrid cell membrane coating supramolecular micelles.

Glioblastoma multiforme (GBM) is one of the most common primary intracranial tumors in the central nervous system with poor prognosis, high invasiveness, risk of recurrence and low survival rate. Thus, it is urgent and vital to develop drug effective delivery systems that efficiently to traverse the blood-brain barrier and targeted transport therapeutic agents into the GBM tumor site for the treatment of brain tumors. Recently, amphiphilic cucurbit[7]uril-polyethylene glycol-hydrophobic Chlorin e6 (CB[7]-PEG-Ce6) polymer was designed, prepared, and self-assembled into micells (CPC) in an aqueous solution, and chemo drug methyl-triazeno-imidazole-carboxamide (MTIC), loaded into the cavity of CB[7] was subsequently coated with hybrid membrane mUMH (HMC3 membrane: macrophage membrane: U87MG membrane = 1:1:2) to afford mUMH@CPC@MTIC. The surface hybrid membrane mUMH potentially enhance the targeted delivery of CPC@MTIC to GBM tissue. Bioactive MTIC was released from the cavity of CB[7] in response to the high spermine level in GBM tumor microenvironments for effective tumor chemotherapy. The biomimetic mUMH@CPC@MTIC exhibited superior antitumor efficacy against GBM in mice. These findings provide new strategies for the design of biomimetic nanoparticle-based drug delivery systems and promising therapy of GBM.

A method for translating search strategies efficiently into HMIC and SPP.

BACKGROUND: Small databases, such as Health Management Information Consortium (HMIC) and Social Policy and Practice (SPP), can add value to systematic searches. Search strategies designed for large databases may not be appropriate in small sources. A different approach to translating strategies could ensure that small databases are searched efficiently. OBJECTIVES: To establish the contribution HMIC and SPP made to public health guidelines (PHGs); and to recommend an efficient method of translating search strategies. METHODS: Eight PHGs were analysed to establish how many included publications were retrieved from HMIC and SPP. Six options for translating strategies from MEDLINE, using variations of free text and subject terms, were compared. RESULTS: Health Management Information Consortium contributed 15 and SPP eight of the 483 publications cited in the PHGs. The free-text only search was the one option to miss an included publication. The heading word (with truncation) option was more precise than applying subject headings. DISCUSSION: There is a risk of missing relevant publications in free-text only searches and it is preferable to include subject terms efficiently. CONCLUSION: The heading word (with truncation) option did not miss the evidence included in the PHGs and was the most efficient method for translating MEDLINE to HMIC and SPP.

Developing a clinically relevant radiosensitizer for temozolomide-resistant gliomas.

The prognosis for patients with glioblastoma (GB) remains grim. Concurrent temozolomide (TMZ) radiation-the cornerstone of glioma control-extends the overall median survival of GB patients by only a few months over radiotherapy alone. While these survival gains could be partly attributed to radiosensitization, this benefit is greatly minimized in tumors expressing O6-methylguanine DNA methyltransferase (MGMT), which specifically reverses O6-methylguanine lesions. Theoretically, non-O6-methylguanine lesions (i.e., the N-methylpurine adducts), which represent up to 90% of TMZ-generated DNA adducts, could also contribute to radiosensitization. Unfortunately, at concentrations attainable in clinical practice, the alkylation capacity of TMZ cannot overwhelm the repair of N-methylpurine adducts to efficiently exploit these lesions. The current therapeutic application of TMZ therefore faces two main obstacles: (i) the stochastic presence of MGMT and (ii) a blunted radiosensitization potential at physiologic concentrations. To circumvent these limitations, we are developing a novel molecule called NEO212-a derivatization of TMZ generated by coupling TMZ to perillyl alcohol. Based on gas chromatography/mass spectrometry and high-performance liquid chromatography analyses, we determined that NEO212 had greater tumor cell uptake than TMZ. In mouse models, NEO212 was more efficient than TMZ at crossing the blood-brain barrier, preferentially accumulating in tumoral over normal brain tissue. Moreover, in vitro analyses with GB cell lines, including TMZ-resistant isogenic variants, revealed more potent cytotoxic and radiosensitizing activities for NEO212 at physiologic concentrations. Mechanistically, these advantages of NEO212 over TMZ could be attributed to its enhanced tumor uptake presumably leading to more extensive DNA alkylation at equivalent dosages which, ultimately, allows for N-methylpurine lesions to be better exploited for radiosensitization. This effect cannot be achieved with TMZ at clinically relevant concentrations and is independent of MGMT. Our findings establish NEO212 as a superior radiosensitizer and a potentially better alternative to TMZ for newly diagnosed GB patients, irrespective of their MGMT status.

NEO212 induces mitochondrial apoptosis and impairs autophagy flux in ovarian cancer.

BACKGROUND: Temozolomide-perillyl alcohol conjugate (NEO212), a novel temozolomide (TMZ) analog, was previously reported to exert its anti-cancer effect in non-small cell lung cancer (NSCLC), and human nasopharyngeal carcinoma (NPC), etc.. In the current study, we intend to illuminate the potential anticancer property and the underly mechanisms of NEO212 in ovarian cancer cells. METHODS: The cytotoxicity of NEO212 was detected by MTT, colony formation analysis and xenograft model. The proteins involved in cell proliferation, DNA damage, autophagy and lysosomal function were detected by western blots; mitochondria, lysosome and autophagosome were visualized by TEM and/or immunofluorescence; Apoptosis, cell cycle analysis and mitochondrial transmembrane potential were detected by flow cytometry. TFEB translocation was detected by immunofluorescence and western blot. RESULTS: NEO212 has the potential anticancer property in ovarian cancer cells, as evidence from cell proliferation inhibition, G2/M arrest, DNA damage, xenograft, mitochondrial dysfunction and apoptosis. Importantly, we observed that although it induced significant accumulation of autophagosomes, NEO212 quenched GFP-LC3 degradation, down-regulated a series of lysosome related gene expression and blocked the autophagic flux, which significantly facilitated it induced apoptosis and was largely because it inhibited the nuclear translocation of transcription factor EB (EB). CONCLUSIONS: NEO212 inhibited TFEB translocation, and impaired the lysosomal function, implying NEO212 might avoid from autophagy mediated chemo-resistance, thus proposing NEO212 as a potential therapeutic candidate for ovarian cancer.

Biophysical interaction of temozolomide and its active metabolite with biomembrane models: The relevance of drug-membrane interaction for Glioblastoma Multiforme therapy.

Temozolomide (TMZ) is the first-line treatment for Glioblastoma Multiforme (GBM). After administration, TMZ is rapidly converted into its active metabolite (MTIC). However, its pharmacological activity is reduced due MTIC low bioavailability in the brain. Since drugs' permeability through biological barriers and tumor cell membranes affects its bioavailability, the ability of MTIC to interact with the biological membranes presents a major contribution on its pharmacological properties and activity. Biomembrane models mimic the physiological conditions, allowing to predict the drug's behavior at biological membranes and its effects on drug biodistribution profiles. In this work, lipid bilayer models using liposomes were applied for the drug-membrane interaction studies. The zwitterionic phospholipid, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and cholesterol were chosen for the composition of the model, since they represent the major components of the membranes of GBM cells and brain capillary endothelial cell. Thus, the molecular interactions between MTIC and these models were studied by the evaluation of the partition of the drug into the phospholipid's membrane, its location within the bilayer and its effect on the fluidity of the membrane. The attained results suggest that the composition of membranes affects drugs partition, showing that drug biodistribution depends not only on its physicochemical features, but also depends on the characteristics of the membrane such as the packing of the lipid molecules. Also, MTIC exhibited low affinity to biological membranes, explaining its low bioavailability on the target cells.

The carbonic anhydrase IX inhibitor SLC-0111 sensitises cancer cells to conventional chemotherapy.

Drug combination represents one of the most accredited strategies of cancer therapy able to improve drug efficacy and possibly overcome drug resistance. Among the agents used to complement conventional chemotherapy, carbonic anhydrase IX (CAIX) inhibitors appear as one of the most suitable, as markers of hypoxic and acidic cancer cells which do not respond to chemo- and radiotherapy. We performed preclinical in vitro assays to evaluate whether the SLC-0111 CAIX inhibitor co-operates and potentiates the cytotoxic effects of conventional chemotherapeutic drugs in A375-M6 melanoma cells, MCF7 breast cancer cells, and HCT116 colorectal cancer cells. Here, we demonstrate that the SLC-0111 CAIX inhibitor potentiates cytotoxicity of Dacarbazine and Temozolomide currently used for advanced melanoma treatment. SLC-0111 also increases breast cancer cell response to Doxorubicin and enhances 5-Fluorouracil cytostatic activity on colon cancer cells. These findings disclose the possibility to extend the use of CAIX inhibitors in the combination therapy of various cancer histotypes.

NEO212, a conjugate of temozolomide and perillyl alcohol, blocks the endothelial-to-mesenchymal transition in tumor-associated brain endothelial cells in glioblastoma.

As the endothelial-to-mesenchymal transition (EndMT) supports the pro-angiogenic and invasive characteristics of glioblastoma multiforme (GBM), blocking this process would be a promising approach to inhibit tumor progression and recurrence. Here, we demonstrate that glioma stem cells (GSC) induce EndMT in brain endothelial cells (BEC). TGF-ß signaling is necessary, but not sufficient to induce this EndMT process. Cell-to-cell contact and the contribution of Notch signaling are also required. NEO212, a conjugate of temozolomide and perillyl alcohol, blocks EndMT induction and reverts the mesenchymal phenotype of tumor-associated BEC (TuBEC) by blocking TGF-ß and Notch pathways. Consequently, NEO212 reduces the invasiveness and pro-angiogenic properties associated with TuBEC, without affecting control BEC. Intracranial co-implantation of BEC and GSC in athymic mice showed that EndMT occurs in vivo, and can be blocked by NEO212, supporting the potential clinical value of NEO212 for the treatment of GBM.

Anti-angiogenic therapy for high-grade glioma.

BACKGROUND: This is an updated version of the original Cochrane Review published in September 2014. The most common primary brain tumours in adults are gliomas. Gliomas span a spectrum from low to high grade and are graded pathologically on a scale of one to four according to the World Health Organization (WHO) classification. High-grade glioma (HGG) carries a poor prognosis. Grade IV glioma is known as glioblastoma and carries a median survival in treated patients of about 15 months. Glioblastomas are rich in blood vessels (i.e. highly vascular) and also rich in a protein known as vascular endothelial growth factor (VEGF) that promotes new blood vessel formation (the process of angiogenesis). Anti-angiogenic agents inhibit the process of new blood vessel formation and promote regression of existing vessels. Several anti-angiogenic agents have been investigated in clinical trials, both in newly diagnosed and recurrent HGG, showing preliminary promising results. This review was undertaken to report on the benefits and harms associated with the use of anti-angiogenic agents in the treatment of HGGs. OBJECTIVES: To evaluate the efficacy and toxicity of anti-angiogenic therapy in people with high-grade glioma (HGG). The intervention can be used in two broad groups: at first diagnosis as part of 'adjuvant' therapy, or in the setting of recurrent disease. SEARCH METHODS: We conducted updated searches to identify published and unpublished randomised controlled trials (RCTs), including the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 9), MEDLINE and Embase to October 2018. We handsearched proceedings of relevant oncology conferences up to 2018. We also searched trial registries for ongoing studies. SELECTION CRITERIA: RCTs evaluating the use of anti-angiogenic therapy to treat HGG versus the same therapy without anti-angiogenic therapy. DATA COLLECTION AND ANALYSIS: Review authors screened the search results and reviewed the abstracts of potentially relevant articles before retrieving the full text of eligible articles. MAIN RESULTS: After a comprehensive literature search, we identified 11 eligible RCTs (3743 participants), of which 7 were included in the original review (2987 participants). There was significant design heterogeneity in the included studies, especially in the response assessment criteria used. All eligible studies were restricted to glioblastomas and there were no eligible studies evaluating other HGGs. Ten studies were available as fully published peer-reviewed manuscripts, and one study was available in abstract form. The overall risk of bias in included studies was low. This risk was based upon low rates of selection bias, detection bias, attrition bias and reporting bias. The 11 studies included in this review did not show an improvement in overall survival with the addition of anti-angiogenic therapy (pooled hazard ratio (HR) of 0.95, 95% confidence interval (CI) 0.88 to 1.02; P = 0.16; 11 studies, 3743 participants; high-certainty evidence). However, pooled analysis from 10 studies (3595 participants) showed improvement in progression-free survival with the addition of anti-angiogenic therapy (HR 0.73, 95% CI 0.68 to 0.79; P < 0.00001; high-certainty evidence).We carried out additional analyses of overall survival and progression-free survival according to treatment setting and for anti-angiogenic therapy combined with chemotherapy compared to chemotherapy alone. Pooled analysis of overall survival in either the adjuvant or recurrent setting did not show an improvement (HR 0.93, 95% CI 0.86 to 1.02; P = 0.12; 8 studies, 2833 participants; high-certainty evidence and HR 0.99, 95% CI 0.85 to 1.16; P = 0.90; 3 studies, 910 participants; moderate-certainty evidence, respectively). Pooled analysis of overall survival for anti-angiogenic therapy combined with chemotherapy compared to chemotherapy also did not clearly show an improvement (HR 0.92, 95% CI 0.85 to 1.00; P = 0.05; 11 studies, 3506 participants; low-certainty evidence). The progression-free survival in the subgroups all showed findings that demonstrated improvements in progression-free survival with the addition of anti-angiogenic therapy. Pooled analysis of progression-free survival in both the adjuvant and recurrent setting showed an improvement (HR 0.75, 95% CI 0.69 to 0.82; P < 0.00001; 8 studies, 2833 participants; high-certainty evidence and HR 0.64, 95% CI 0.54 to 0.76; P < 0.00001; 2 studies, 762 participants; moderate-certainty evidence, respectively). Pooled analysis of progression-free survival for anti-angiogenic therapy combined with chemotherapy compared to chemotherapy alone showed an improvement (HR 0.72, 95% CI 0.66 to 0.77; P < 0.00001; 10 studies, 3464 participants). Similar to trials of anti-angiogenic therapies in other solid tumours, adverse events related to this class of therapy included hypertension and proteinuria, poor wound healing, and the potential for thromboembolic events, although generally, the rate of grade 3 and 4 adverse events was low (< 14.1%) and in keeping with the literature. The impact of anti-angiogenic therapy on quality of life varied between studies. AUTHORS' CONCLUSIONS: The use of anti-angiogenic therapy does not significantly improve overall survival in newly diagnosed people with glioblastoma. Thus, there is insufficient evidence to support the use of anti-angiogenic therapy for people with newly diagnosed glioblastoma at this time. Overall there is a lack of evidence of a survival advantage for anti-angiogenic therapy over chemotherapy in recurrent glioblastoma. When considering the combination anti-angiogenic therapy with chemotherapy compared with the same chemotherapy alone, there may possibly be a small improvement in overall survival. While there is strong evidence that bevacizumab (an anti-angiogenic drug) prolongs progression-free survival in newly diagnosed and recurrent glioblastoma, the impact of this on quality of life and net clinical benefit for patients remains unclear. Not addressed here is whether subsets of people with glioblastoma may benefit from anti-angiogenic therapies, nor their utility in other HGG histologies.

The clinical value of using chloroquine or hydroxychloroquine as autophagy inhibitors in the treatment of cancers: A systematic review and meta-analysis.

BACKGROUND: Autophagy is a mechanism which relies on lysosomes for clearance and recycling of abnormal proteins or organelles. Many studies have demonstrated that the deregulation of autophagy is associated with the development of various diseases including cancer. The use of autophagy inhibitors is an emerging trend in cancer treatment. However, the value of autophagy inhibitors remains under debate. Thus, a meta-analysis was performed, aiming to evaluate the clinical value of autophagy-inhibitor-based therapy. METHODS: We searched for clinical studies that evaluated autophagy-inhibitor-based therapy in cancer. We extracted data from these studies to evaluate the relative risk (RR) of overall response rate (ORR), 6-month progression-free survival (PFS) rate, and 1-year overall survival (OS) rate. RESULTS: Seven clinical trials were identified (n = 293). Treatments included 2 combinations of hydroxychloroquine and gemcitabine, 1 combination of hydroxychloroquine and doxorubicin, 1 combination of chloroquine and radiation, 2 combinations of chloroquine, temozolomide, and radiation, and 1 hydroxychloroquine monotherapy. Autophagy-inhibitor-based therapy showed higher ORR (RR: 1.33, 95% confidence interval [CI]: 0.95-1.86, P = .009), PFS (RR: 1.72, 95% CI: 1.05-2.82, P = .000), OS (RR: 1.39, 95% CI: 1.11-1.75, P = .000) values than the therapy without inhibiting autophagy. CONCLUSION: This meta-analysis showed that autophagy-inhibitor-based therapy has better treatment response compared to chemotherapy or radiation therapy without inhibiting autophagy, which may provide a new strategy for the treatment of cancers.

Effect of Endostar combined with chemotherapy in advanced well-differentiated pancreatic neuroendocrine tumors.

The aim of the present study was to assess the effect of Endostar and temozolomide or dacarbazine plus 5-fluorouracil (5-FU) in patients with advanced pancreatic neuroendocrine tumors (pNETs).Phase II study of 14 patients with locally advanced or metastatic well-differentiated pNETs treated between April 2013 and September 2016. Patients received temozolomide or dacarbazine plus 5-FU, and Endostar. The primary outcome was the radiographic response rate.All 14 patients had nonfunctional pNETs. Six patients received temozolomide and 8 received dacarbazine + 5-FU, combined with Endostar. Thirteen patients were assessable for treatment response: 1(7%) with complete response, 5 (39%) with partial response, 5 (39%) with stable disease, and 2 (15%) with progression. The median progression-free survival was 12 months. The most common grade 1/2 toxicities were neutropenia (43%) and leucopenia (21%).Endostar combined with temozolomide or dacarbazine + 5-FU was effective in the treatment of advanced pNETs. The combinations were well tolerated.

Safety and efficacy of combining capecitabine and temozolomide (CAPTEM) to treat advanced neuroendocrine neoplasms: A meta-analysis.

Retrospective studies have suggested that capecitabine combined with temozolomide (CAPTEM) is effective for treating patients with advanced neuroendocrine neoplasms (NENs); however, the efficacy and safety of this regimen needs to be verified by high-quality evidence or results of randomized controlled trials.We carried out a meta-analysis to evaluate the safety and effectiveness of a CAPTEM protocol for patients with advanced NENs. Systematic electronic literature searches were conducted using PubMed, EMBASE, and the Cochrane Library, and among meeting abstracts of the American Society of Clinical Oncology, European Society for Medical Oncology, European Neuroendocrine Tumor Society, and North American Neuroendocrine Tumor Society, up to June 30, 2017. We selected studies describing CAPTEM regimens for treating advanced NENs and reported on tumor response and/or toxicities according to clear World Health Organization (WHO) grading of patients. Three reviewers independently and repeatedly identified studies, extracted data, and assessed the quality of the literature. A single-proportion meta-analysis was applied to included articles.Fifteen studies with a total of 384 individuals were included. Medium overall survival in most studies was more than 12 months, whereas medium progression-free survival was similar or slightly higher than that in studies using other treatment regimes. Disease control rate of CAPTEM administration for patients with NENs was 72.89% (95% confidence interval, 64.04-81.73%; I = 82.4%; P < .01). WHO grade 3 to 4 toxicities, such as thrombocytopenia (3.36%), neutropenia (0.69%), lymphopenia (0.65%), anemia (0.59%), mucositis (0.57%), fatigue (0.54%), diarrhea (0.49%), nausea (0.39%), and transaminase elevation (0.13%) were reported in the trials included.CAPTEM is effective and relatively safe for treating patients with advanced NENs.

Juniperus Communis Extract Exerts Antitumor Effects in Human Glioblastomas Through Blood-Brain Barrier.

BACKGROUND/AIMS: Herbal materials derived from Juniperus communis (JCo) possess anticancer activity. In this study, we evaluated the efficacy of a JCo berry extract in suppressing glioblastoma growth. METHODS: The effects of JCo extract on the viability of normal and glioma cell lines was analyzed using a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The synergistic therapeutic effect of JCo extract and temozolomide (TMZ) on glioma cells was examined by MTT analysis. Flow cytometry analysis, the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) test, and western blotting were performed to identify the apoptotic pathway. To determine the in vivo efficacy of the JCo extract, rats were injected with 5 × 104 rat glioma RG2 cells in the back skin and brain hemisphere and then received a subcutaneous injection in the back skin that contained either JCo extract or vehicle. Finally, blood and histologic examinations were performed to evaluate JCo toxicity. RESULTS: The IC50 values of JCo extract were 57-69 µg/mL and 49-67 µg/mL in the glioblastoma cell lines after 24 and 48 h, respectively. However, in non-tumor cell lines, the respective IC50 values of JCo extract were 76-105 µg/mL and 77-108 µg/mL. The JCo extract had a stronger cytotoxicity and a larger range of IC50 values in glioma than in normal cells as compared to those effects caused by temozolomide (TMZ). In addition, the results of flow cytometry analysis, TUNEL test, and western blotting revealed that the JCo extract induced glioma cell cycle arrest through intrinsic and extrinsic apoptotic pathways. In the in vivo studies, a significant reduction of tumor size in JCo-treated rats, as measured by animal MRI, demonstrated that the JCo extract effectively inhibited glioma cell growth and successfully penetrated the blood-brain barrier. The immunohistochemical (IHC) staining detected positive signals of PCNA, VEGFR-1, and VEGFR -2 in 44.49%, 5.88%, and 5.85% of JCo-treated glioma cells, respectively. However, positive signals of PCNA, VEGFR-1, and VEGFR-2 were detected in 73.08%, 9.67%, and 11.70% of vehicle-treated glioma cells, respectively. The IHC examination of PCNA and VEGFR-1 and -2 indicated that JCo extract significantly decreased the degree of neovascularization. However, no significant differences in serum levels of blood cell count and hepatic enzymes, renal function index, and the histologic appearance of vital organs were detected between the JCo and vehicle-treated rats. CONCLUSION: The JCo extract penetrated the blood-brain barrier and significantly induced glioma cell apoptosis by reducing neovascularization via suppression of the PI3K/AKT/mTOR pathway. Furthermore, JCo extract was less cytotoxic to non-neoplastic vital organs than TMZ.

Honokiol enhances temozolomide-induced apoptotic insults to malignant glioma cells via an intrinsic mitochondrion-dependent pathway.

BACKGROUND: Temozolomide (TMZ) is a first-line chemotherapeutic drug for malignant gliomas. Nonetheless, TMZ-induced side effects and drug resistance remain challenges. Our previous study showed the suppressive effects of honokiol on growth of gliomas. PURPOSE: This study was further aimed to evaluate if honokiol could enhance TMZ-induced insults toward malignant glioma cells and its possible mechanisms. METHODS: Human U87 MG glioma cells were exposed to TMZ, honokiol, and a combination of TMZ and honokiol. Cell survival, apoptosis, necrosis, and proliferation were successively assayed. Fluorometric substrate assays were conducted to determine activities of caspase-3, -6, -8, and -9. Levels of Fas ligand, Bax, and cytochrome c were immunodetected. Translocation of Bax to mitochondria were examined using confocal microscopy. Mitochondrial function was evaluated by assaying the mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and complex I enzyme activity. Caspase-6 activity was suppressed using specific peptide inhibitors. The honokiol-induced effects were further confirmed using human U373 MG and murine GL261 cells. RESULTS: Exposure of human U87 MG glioma cells to honokiol significantly increased TMZ-induced DNA fragmentation and cell apoptosis. Interestingly, honokiol enhanced intrinsic caspase-9 activity without affecting extrinsic Fas ligand levels and caspase-8 activity. Sequentially, TMZ-induced changes in Bax translocation, the MMP, mitochondrial complex I enzyme activity, intracellular ROS levels, and cytochrome c release were enhanced by honokiol. Consequently, honokiol amplified TMZ-induced activation of caspases-3 and -6 in human U87 MG cells. Fascinatingly, suppressing caspase-6 activity concurrently decreased honokiol-induced DNA fragmentation and cell apoptosis. The honokiol-involved improvement in TMZ-induced intrinsic apoptosis was also confirmed in human U373 MG and murine GL261 glioma cells. CONCLUSIONS: This study showed that honokiol can enhance TMZ-induced apoptotic insults to glioma cells via an intrinsic mitochondrion-dependent mechanism. Our results suggest the therapeutic potential of honokiol to attenuate TMZ-induced side effects.

Synergistic effect of temozolomide and thymoquinone on human glioblastoma multiforme cell line (U87MG).

AIMS: Temozolomide (TMZ) is an alkylating agent used for glioblastoma multiforme (GBM) treatment. Nevertheless, resistance to TMZ is a major obstacle to successful treatment of this cancer. The aim of the present study was to investigate the effects of TMZ and thymoquinone (TQ) on U87MG cell line. MATERIALS AND METHODS: The effect of TMZ and/or TQ on viability and invasion potential of U87MG cells was evaluated using various techniques including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, lactate dehydrogenase activity, cell invasion, migration, and adhesion assays. Enzyme-linked immunosorbent assay and polymerase chain reaction were used to study the expression and secretion of matrix metalloproteinases (MMPs). RESULTS: Combination of TMZ and TQ had a synergistic cytotoxic effect on U87MG cells. TMZ and/or TQ significantly reduced the potential of U87MG cells invasion. In addition, after treating with TMZ and/or TQ, there was a decrease in the levels of matrix matrix metalloproteinase 2 nad 9 (MMP 2 and 9) expression and secretion in U87MG cells. CONCLUSIONS: The combination of TMZ and TQ may emerge as a promising strategy for the successful treatment of GBM.

Durable complete response with a short course of streptozotocin plus doxorubicin combination in malignant metastatic insulinoma.

Due to the cytotoxic effects of old chemotherapy regimens used in the islet cell tumors, capecitabine plus temozolomide combination has now become the first choice in the treatment of malignant insulinoma (MIoma). We present this case to emphasize and remind that a durable complete response in advanced stage MIoma may be achieved with a short course of streptozotocin plus doxorubicin combination.

Drug resistance in glioblastoma and cytotoxicity of seaweed compounds, alone and in combination with anticancer drugs: A mini review.

BACKGROUND: Glioblastomas (GBM) are one of the most aggressive tumor of the central nervous system with an average life expectancy of only 1-2 years after diagnosis, even with the use of advanced treatments with surgery, radiation, and chemotherapy. There are several anticancer drugs with alkylating properties that have been used in the therapy of malignant gliomas. Temozolomide (TMZ) is one of them, widely used even in combination with ionizing radiation. However, the main disadvantage of using these types of drugs in the treatment of GBM is the development of cancer drug resistance. Research of bioactive compounds with anticancer activity has been heavily explored. PURPOSE: This review focuses on a carotenoid and a phlorotannin present in seaweed, namely fucoxanthin and phloroglucinol, and their anticancer activity against glioblastoma. The combination of natural compounds with conventional drugs is also discussed. CONCLUSION: Several natural compounds existing in seaweeds, such as fucoxanthin and phoroglucinol, have shown cytotoxic activity in models in vitro and in vivo, acting through different molecular mechanisms, such as antioxidant, antiproliferative, DNA damage/DNA repair, proapoptotic, antiangiogenic and antimetastic. Within the scope of interactions with conventional drugs, there are evidences that some seaweed compounds could be used to potentiate the action of anticancer drugs. However, their effects and mechanisms of action, alone or in combination with anticancer drugs, namely TMZ, in glioblastoma cell, still few explored and require more attention due to the unquestionable high potential of these marine compounds.

Cell Subpopulations Overexpressing p75NTR Have Tumor-initiating Properties in the C6 Glioma Cell Line.

BACKGROUND/AIM: Glioma is the most common and lethal primary brain tumor. Even with the development of multidisciplinary treatment approaches, results are disappointing because of the unavoidable tumor recurrence, which may be caused by the existence of tumor-initiating cells. The p75 neurotrophin receptor (p75NTR), which belongs to the tumor necrosis factor receptor superfamily, is not only involved in various cellular functions but also related to tumor growth. This study is focused, on the possible role of p75NTR in glioma tumor initiation. MATERIALS AND METHODS: C6 cells with high and low expression of p75NTR were sorted using flow cytometry. The neurosphere characteristics and properties of these two subpopulations were assessed and compared with those of parental cells. Radiation and chemotherapy sensitivity was also analyzed in these cell populations. Finally, in vivo tumorigenicity of cells was tested in a rat model. RESULTS: Cells overexpressing p75NTR (C6p75+++ cells) demonstrated greater ability of neurosphere formation, colony proliferation, and certain stem cell marker overexpression than cells with low p75NTR expression (C6p75+) and parental cells. In addition, following irradiation or temozolomide treatment, more viable C6p75+++ cells remained, and they proliferated into more colonies. In vivo, C6p75+++ cell implantation in Sprague Dawley rats reduced the survival time. CONCLUSION: Cells with p75NTR overexpression demonstrated certain unique characteristics of tumor-initiating cells, such as neurosphere formation, high colony proliferation, and resistance to radio- and chemotherapy. With regard to the heterogeneous composition of glioma cells, p75NTR can be used as an alternative marker to identify a glioma subpopulation with tumor-initiating properties.