Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Malignant gliomas are highly lethal neoplasms that cannot be cured with currently available therapies. Temozolomide (TMZ) is a recently introduced alkylating agent that has yielded significant benefits and become a key agent in the treatment of high-grade gliomas. However, its survival benefit remains unsatisfactory. Understanding the molecular basis of TMZ sensitivity/resistance is necessary for improving the treatment outcome by devising strategies that are able to circumvent primary drug resistance. We therefore combined the in vitro TMZ response with microarray gene expression data to identify genes that could potentially be used to predict the response of malignant gliomas to TMZ therapy. We first obtained the individual IC50 values for TMZ in seven malignant glioma cell lines (A-172, AM-38, T98G, U-87MG, U-138MG, U-251MG and YH-13) and then identified the genes whose expression correlated most highly with TMZ sensitivity employing a cDNA microarray. We present here a list of the most highly up-regulated and down-regulated genes which may be involved in conferring TMZ sensitivity/resistance in malignant gliomas, although most of the genes have not been implicated as a causal factor in the TMZ response except MGMT. We also demonstrated and confirmed the MGMT methylation status, quantitative MGMT mRNA levels, and MGMT protein expression levels in TMZ resistant glioma cells in vitro. Our results are thus consistent with previous studies and suggest that a dominant mechanism conferring sensitivity/resistance to TMZ exists in malignant glioma cells. Although the present study dose have several limitations, our reported candidate genes could represent not only potential molecular markers for TMZ sensitivity/resistance but also chemotherapy targets. Furthermore, the present study could provide a foundation for alternative therapeutic strategies including novel combination treatments that incorporate additional reagents directed at overcoming resistance to TMZ.
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PMID:Gene expression profiling predicts response to temozolomide in malignant gliomas. 2042 59

Malignant gliomas are the most common and deadly brain tumors. Nevertheless, survival for patients with glioblastoma, the most aggressive glioma, although individually variable, has improved from an average of 10 months to 14 months after diagnosis in the last 5 years due to improvements in the standard of care. Radiotherapy has been of key importance to the treatment of these lesions for decades, and the ability to focus the beam and tailor it to the irregular contours of brain tumors and minimize the dose to nearby critical structures with intensity-modulated or image-guided techniques has improved greatly. Temozolomide, an alkylating agent with simple oral administration and a favorable toxicity profile, is used in conjunction with and after radiotherapy. Newer surgical techniques, such as fluorescence-guided resection and neuroendoscopic approaches, have become important in the management of malignant gliomas. Furthermore, new discoveries are being made in basic and translational research, which are likely to improve this situation further in the next 10 years. These include agents that block 1 or more of the disordered tumor proliferation signaling pathways, and that overcome resistance to already existing treatments. Targeted therapies such as antiangiogenic therapy with antivascular endothelial growth factor antibodies (bevacizumab) are finding their way into clinical practice. Large-scale research efforts are ongoing to provide a comprehensive understanding of all the genetic alterations and gene expression changes underlying glioma formation. These have already refined the classification of glioblastoma into 4 distinct molecular entities that may lead to different treatment regimens. The role of cancer stem-like cells is another area of active investigation. There is definite hope that by 2020, new cocktails of drugs will be available to target the key molecular pathways involved in gliomas and reduce their mortality and morbidity, a positive development for patients, their families, and medical professionals alike.
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PMID:Exciting new advances in neuro-oncology: the avenue to a cure for malignant glioma. 2044

Gliomas are the mostfrequent subtype of primary brain tumors. They are lethal tumors, characterized by diffuse infiltration of the brain and a high resistance to conventional cancer therapies. Following maximal neurosurgical resection, bound to the limits of acceptable neurological sequelae, immediate post-operative radiotherapy is indicated in the majority of patients. Chemotherapy with the alkylating agent temozolomide, administered daily concomitantly to radiotherapy, and followed by six adjuvant monthly cycles, significantly improves the survival of newly diagnosed glioblastoma patients and has become the standard of care. Temozolomide is also the most often used chemotherapeutic treatment for recurrent low-grade and anaplastic gliomas after initial surgery and irradiation. The potential role of postoperative temozolomide in the first line treatment for low-grade and anaplastic glioma is currently under investigation in phase III trials. After failure of temozolomide, there is only limited activity of any other cytotoxic agent and the benefit of such second line therapy seems to be limited to a small subgroup of patients with the most chemosensitive gliomas. Abnormal hypermethylation of the promoter of the MGMT gene has been correlated with the response of glioma to alkylating chemotherapy. The loss of chromosomal arms 1p and 19q are genetic markers characteristic for gliomas with oligodendroglial differentiation which are also most sensitive to treatment. The predictive and prognostic value of these molecular markers is currently being determined prospectively in phase III studies. Anti-angiogenic agents and targeted receptor tyrosine kinase inhibitors are new pharmacological classes with activity against malignant gliomas. Phase III clinical studies evaluating combinations of these new agents with classical cytotoxic agents in first and in second line have recently been initiated.
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PMID:The role of cytotoxic drugs in the treatment of central nervous system gliomas. 2051 22

Temozolomide is an oral alkylating agent with established antitumor activity in patients with primary brain tumors and melanoma. The originally approved temozolomide dosing regimen is 150 to 200 mg/m(2) per day (Days 1 to 5 every 28-day cycle [5 of 28 days]). However, extended dosing regimens (eg, 7 of 14 days, 21 of 28 days, 6 of 8 weeks, or continuously daily) allow for administration of a higher cumulative dose per cycle and have been shown to deplete O(6)-methylguanine-DNA methyltransferase, which may enhance cytotoxic activity. This article reviews efficacy and safety data from studies that investigated dose-dense temozolomide regimens in patients with recurrent glioma and advanced metastatic melanoma. The clinical benefits of these dose-dense regimens compared with the standard 5 of 28-day regimen have yet to be established. Although the toxicity profile of dose-dense temozolomide is generally similar to that of the standard 5 of 28-day regimen, it is associated with an increased incidence and severity of lymphocytopenia. The clinical management of temozolomide-associated lymphodepletion and the potential risks and benefits of extended dosing with temozolomide are discussed. Preclinical and clinical evidence suggests that temozolomide-associated lymphodepletion may enhance the host immune response to tumor-associated antigens and/or immunotherapy and may overcome tumor-mediated immunosuppression. Further studies exploring the clinical implications of lymphodepletion are warranted.
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PMID:Dose-dense temozolomide regimens: antitumor activity, toxicity, and immunomodulatory effects. 2056 93

Prognosis for the patients with glioblastoma, the most common malignant brain tumor, remains dismal. A major barrier to progress in treatment of glioblastoma is the relative inaccessibility of tumors to chemotherapeutic agents. Convection-enhanced delivery (CED) is a direct intracranial drug infusion technique to deliver chemotherapeutic agents to the central nervous system, circumventing the blood-brain barrier and reducing systemic side effects. CED can provide wider distribution of infused agents compared to simple diffusion. We have reported that CED of a polymeric micelle carrier system could yield a clinically relevant distribution of encapsulated agents in the rat brain. Our aim was to evaluate the efficacy of CED of polymeric micellar Am80, a synthetic agonist with high affinity to nuclear retinoic acid receptor, in a rat model of glioblastoma xenografts. We also used systemic administration of temozolomide, a DNA-alkylating agent, which has been established as the standard of care for newly diagnosed malignant glioma. U87MG human glioma cells were injected into the cerebral hemisphere of nude rats. Rats bearing U87MG xenografts were treated with CED of micellar Am80 (2.4 mg/m(2)) on day 7 after tumor implantation. Temozolomide (200 mg/m(2)/day) was intraperitoneally administered daily for 5 days, starting on day 7 after tumor implantation. CED of micellar Am80 provided significantly longer survival than the control. The combination of CED of micellar Am80 and systemic administration of temozolomide provided significantly longer survival than single treatment. In conclusion, temozolomide combined with CED of micellar Am80 may be a promising method for the treatment of malignant gliomas.
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PMID:Convection-enhanced delivery of a synthetic retinoid Am80, loaded into polymeric micelles, prolongs the survival of rats bearing intracranial glioblastoma xenografts. 2062 91

MicroRNAs (miRNAs) are small noncoding RNA molecules that regulate protein expression by cleaving or repressing the translation of target mRNAs. In mammal animals, their function mainly represses the target mRNAs transcripts via imperfectly complementary to the 3'UTR of target mRNAs. Several miRNAs have been recently reported to be involved in modulation of glioma development, especially some up-regulated miRNAs, such as microRNA-21 (miR-21), which has been found to function as an oncogene in cultured glioblastoma multiforme cells. Temozolomide (TMZ), an alkylating agent, is a promising chemotherapeutic agent for treating glioblastoma. However, resistance develops quickly and with high frequency. To explore the mechanism of resistance, we found that miR-21 could protect human glioblastoma U87MG cells from TMZ induced apoptosis. Our studies showed that TMZ markedly enhanced apoptosis in U87MG cells compared with untreated cells (P<0.05). However, over-express miR-21 in U87MG cells could significantly reduce TMZ-induced apoptosis (P<0.05). Pro-apoptotic Bax and anti-apoptotic Bcl-2 proteins are known to regulate the apoptosis of glioma cells. Bcl-2, resistance to induction of apoptosis, constitutes one major obstacle to chemotherapy in many cancer cells. Bax is shown to correlate with an increased survival of glioblastoma multiforme patients. Further research demonstrated that the mechanism was associated with a shift in Bax/Bcl-2 ratio and change in caspase-3 activity. Compared to control cells, cells treated with TMZ showed a significant increase in the Bax/Bcl-2 ratio and caspase-3 activity (P<0.01). However, such effect was partly prevented by treatment of cells with miR-21 overexpression before, which appeared to downregulate the Bax expression, upregulate the Bcl-2 expression and decrease caspase-3 activity. Taken together, these results suggested that over-express miR-21 could inhibit TMZ-induced apoptosis in U87MG cells, at least in part, by decreasing Bax/Bcl-2 ratio and caspase-3 activity, which highlighted the possibility of miR-21 overexpression in the clinical resistance to chemotherapeutic therapy of TMZ.
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PMID:MiR-21 protected human glioblastoma U87MG cells from chemotherapeutic drug temozolomide induced apoptosis by decreasing Bax/Bcl-2 ratio and caspase-3 activity. 2063 39

The aim of the present study was to investigate the effect of Temozolomide (an alkylating chemotherapeutic agent) and quercetin (natural flavonoid) on cell death in the human astrocytoma cell line MOGGCCM (WHO grade III). Our results indicate that Temozolomide induces autophagy, while quercetin promotes severe necrosis in the cell line in a manner dependent on the drug concentration. We demonstrated for the first time that combinations of both drugs were much more effective in programmed cell death induction in glioma cells. At a low (5muM) drug concentration, quercetin potentiated a pro-autophagic effect of Temozolomide, while after treatment with a higher drug concentration (30muM), autophagy switched to apoptosis. Temozolomide attenuated the toxic effect of quercetin. Apoptosis was mediated by the mitochondrial pathway and the activation of caspase 3 and cytochrome C release, but no changes in caspase 8 expression was observed. It was accompanied by decreased mitochondrial membrane potential and inhibition of Hsp27 and Hsp72 expression. Autophagy was correlated with an increased level of LC3II. Temozolomide and quercetin also inhibited migratory phenotype of MOGGCCM cells and changed the nuclei morphology from a circular to an irregular shape. Our results indicate that quercetin acts in synergy with Temozolomide and when used in combination rather than in separate pharmacological application, both drugs are more effective in programmed cell death induction. Temozolomide administered with quercetin seems to be a potent and promising combination which might be useful in glioma therapy.
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PMID:Temozolomide, quercetin and cell death in the MOGGCCM astrocytoma cell line. 2065 99

Two young male patients treated seven and four years back, for malignant glioma, returned with recurrence at the same site, with a World Health Organization (WHO) Performance Score of four and two. Both underwent resurgery and received postoperative reirradiation of 5040 cGy in 28 fractions and concurrent Temozolomide 75 mg/m(2) body surface area (BSA) daily, and one patient received additional adjuvant Temozolomide 250 mg (150 mg/m(2) BSA). Both patients tolerated the treatment well with 16 and 14 months follow-up from the time of recurrence. They were symptom-free, with normal physical function and good mental state, and resumed their respective jobs.
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PMID:Palliative Benefits of the Multimodality Approach in the Re-treatment of Recurrent Malignant Glioma: Two Case Reports. 2066 97

Temozolomide (TMZ) is an oral alkylating agent with proven antitumoral activity in preclinical and clinical studies in adults with high-grade glioma (HGG). However, only limited efficacy has been reported in children with HGG using the 5-day schedule. This study investigated the safety of administering TMZ to children and adolescents with brain tumors over an extended period. Extended schedules have been proven to overcome chemoresistance without any major toxicity. The toxicity of TMZ, administered at 70 mg/m(2)/day orally for 21 consecutive days every 28 days, was assessed in children with brain tumors. A total of 156 courses of TMZ were given to 17 patients (median age 12.5 years, range 1-17 years), who were recruited into the study. Eleven patients had progressive or relapsing disease, and six patients were newly diagnosed. In this cohort no cases of toxic death or nonhematological toxicity were reported. In comparison with the 5-day schedule, thrombocytopenia and neutropenia were noted to be less frequent. Grades 3 and 4 lymphopenia occurred in 10.8 and 22.4% of courses, respectively; among the lymphopenic patients there was one case of disseminated zoster (meningoencephalitis and cutaneous involvement), one case of rotavirus gastroenteritis, and two cases of herpetic stomatitis reported. The objective response rate was 11.8%. Overall, 82.3% of patients showed stable disease. The prolonged TMZ schedule appeared to be well tolerated, with few cases of neutropenia or thrombocytopenia recorded. Nevertheless, prolonged exposure to TMZ was associated with lymphopenia and may lead to a higher rate of viral infections.
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PMID:Feasibility study of 21-day-on/7-day-off temozolomide in children with brain tumors. 2081 28

Temozolomide (TM) has anti-tumor activity in patients with malignant glioma. Implantable poly (D,L-lactide-co-glycolide) (PLGA) microparticles of TM (TM-MS) have been developed, enhancing the cytotoxicity of TM to Glioma C6 cells. Vatalanib, as anti-angiogenic agent, has also shown anti-tumor activity with malignant gliomas. We examined the combined effects of TM-MS and vatalanib in a rat orthotopic glioma model and found TM-MS offered a greater tumor inhibition than TM, and combination treatment with both of them improved the survival time versus single agent therapy. The combination treatment also demonstrated an inhibition to rat glioma tumors, a significant decrease in cell proliferation, an increase in apoptosis, and a lower microvessel density within the glioma tumors. The results suggest that TM-MS can more effectively inhibit tumor than TM, and combination treatment with TM-MS and vatalanib inhibits tumor growth and angiogenesis and may prove to be a promising therapy for malignant gliomas.
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PMID:Temozolomide/PLGA microparticles plus vatalanib inhibits tumor growth and angiogenesis in an orthotopic glioma model. 2081 59


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