Emerging functions of microRNAs in glioblastoma

Distinct patterns of microRNA expression have been observed in glioblastomas. The functional significance of some of these microRNAs is beginning to emerge. This data indicates that microRNAs play roles in multiple hallmark biological characteristics of glioblastoma, including cell proliferation, invasion, glioma stem cell behavior, and angiogenesis. Research in this area is quickly gathering pace and is illuminating important aspects of the disease that may ultimately lead to novel therapeutic interventions, as well as diagnostic and prognostic tools for brain tumors.     

Role of microRNAs in glioblastoma

Glioblastoma is the most common and aggressive primary human brain cancer. MicroRNAs (miRNAs) are a set of small endogenous non-coding RNA molecules which play critical roles in different biological processes including cancer. The realization of miRNA regulatory functions in GBM has demonstrated that these molecules play a critical role in its initiation, progression and response to therapy. In this review we discuss the studies related to miRNA discovery and function in glioblastoma. We first summarize the typical miRNAs and their roles in GBM. Then we debate the potential for miRNA-based therapy for glioblastoma, including various delivery strategies. We surmise that future directions identified by these studies will point towards the necessity for therapeutic development and optimization to improve the outcomes for patients with glioblastoma.     

Multifocal glioblastoma multiforme: prognostic factors and patterns of progression

PURPOSE: To assess the progression patterns in patients with multifocal glioblastoma multiforme who had undergone whole brain radiotherapy (WBRT), the historical standard, versus three-dimensional conformal radiotherapy, and to identify predictive treatment and pretreatment factors. METHODS AND MATERIALS: The records of 50 patients with multifocal glioblastoma multiforme treated with RT were reviewed. Univariate analyses were performed using survival methods and the Cox proportional hazards regression method. Multivariate analyses were performed using the Cox proportional hazards regression method. RESULTS: The mean age was 61 years, and 71% had a Karnofsky performance status (KPS) score of > or =70. Of the 50 patients, 32% underwent WBRT and 68%, three-dimensional conformal RT. Progression was local in all evaluable patients, as determined by imaging in 38 patients and early neurologic progression in 12. The median time to progression (TTP) was 3.1 months, and the median survival time (MST) was 8.1 months. The significant independent predictors of TTP on multivariate analysis were a KPS score <70 (p = 0.001), the extent of surgery (p = 0.040), a radiation dose <60 Gy (p = 0.027), and the lack of chemotherapy (p = 0.001). The significant independent predictors of a reduced MST were a KPS score <70 (p = 0.022) and the absence of salvage surgery (p = 0.011) and salvage chemotherapy (p = 0.003). CONCLUSION: Local progression was observed in all patients. On multivariate analysis, no significant difference was found in the TTP or MST between three-dimensional conformal radiotherapy and WBRT. The KPS was a consistent independent predictor of both TTP and MST. On the basis of the progression pattern, we do not recommend WBRT as a mandatory component of the treatment of multifocal glioblastoma multiforme.     

Cisplatinum and BCNU chemotherapy in primary glioblastoma patients

Background The prognosis of patients with glioblastoma is very poor with a mean survival of 10–12 months. Currently available treatment options are multimodal, which include surgery, radiotherapy, and chemotherapy. However, these have been shown to improve survival only marginally in glioblastoma multiforme (GBM) patients. Methylated methylguanine methyltransferase (MGMT) promoter is correlated with improved progression-free and overall survival in patients treated with alkylating agents. Strategies to overcome MGMT-mediated chemoresistance are being actively investigated. Methods A retrospective analysis on 160 adult patients (≥16 years) treated for histologically confirmed GBM between 2003 and 2005 at our Institution was performed. All patients were treated with conventional fractionated radiotherapy and a combined chemotherapy treatment with Cisplatin (CDDP) (100 mg/sqm on day 1) and carmustine (BCNU) (160 mg/sqm on day 2); the treatment was repeated every 6 weeks for five cycles. Toxicity, progression free survival and overall survival were assessed. Results The median number of chemotherapy cycles delivered to each patient was 5 (range 3–6), with no patients discontinuing treatment because of refusal or toxicity. Dose reduction was required in 16 patients (10%), and all patients completed radiotherapy, whereas 5 patients discontinued chemotherapy before completing all planned cycles for disease progression. The primary toxicities were: neutropenia (grade 3–4: 23%), thrombocytopenia (grade 3–4: 18.5%), and nausea and vomiting (13%). Median progression-free survival times and 1-year progression free survival were 7.6 months (95% CI 6.6–8.5) and 17.3%, respectively. OS was 15.6 months (95% CI 14.1–17.1). Conclusions Our results for PFS and overall survival are comparable with those obtained with temozolomide, but the toxicity occurring in our series was more frequent and persistent. The toxicity, and mainly the modalities of administration associated with cisplatin and BCNU combination, argues against future use in the treatment of patients with GBM.     

MGMT prognostic impact on glioblastoma is dependent on therapeutic modalities

MGMT promoter methylation, which has been correlated with the response to alkylating agents, was investigated in a retrospective series of 219 glioblastomas (GBMs) treated with various modalities. MGMT methylation had no impact on survival for the whole group, but showed a significant advantage (17.1 months vs. 13.1) for patients treated with RT+ adjuvant chemotherapy (relative risk of death (RR) = 0.53; P = 0.041), particularly when patients received CT during the course of RT (MS = 19.9 months vs. 12.5 months; RR = 0.227, P = 0.001). This suggests that the prognostic impact of MGMT methylation is dependent on therapeutic modalities and schedules. MGMT methylation was not correlated with the main molecular alterations, such as 10q loss and p53 expression.     

The prognostic significance of midline shift at presentation on survival in patients with glioblastoma multiforme

Purpose: While patients with glioblastoma multiforme (GBM) who present with midline shift have a presumably worse prognosis, there is little literature evaluating the prognostic significance of this presentation in multivariate analysis in the context of other known prognostic factors.

Methods and Materials: From March 1981 to September 1993, 219 patients underwent irradiation for intracranial glioma at our institution. One hundred fourteen patients with a diagnosis of a primary GBM were analyzed for the influence of the presence of midline shift at diagnosis on survival with respect to other known prognostic factors, including age, Karnofsky performance status (KPS), and extent of surgery. Eighty-five patients (74%) presented with midline shift. Surgical treatment consisted of subtotal/total resection in 86 patients (75%). Among patients presenting with midline shift, 68 (80%) underwent subtotal/total resection before irradiation.

Results: Multivariate analysis of the entire cohort of patients found none of the potential prognostic factors analyzed to significantly influence survival. The overall median survival was 6 months. However, when multivariate analysis was limited to patients with a KPS of ≥ 70, only the presence of midline shift and age were found to significantly influence survival. Patients with a KPS ≥ 70 and with midline shift present at diagnosis had a median survival of 8 months, as compared to 14 months for those not having midline shift at presentation (p = 0.04). Patients with a KPS ≥ 70 and age > 50 years had a median survival of 5 months as compared to 11 months for those ≤ 50 (p = 0.02).

Conclusion: In this series, where 80% of patients who presented with a midline shift underwent decompressive resection of GBM before irradiation, the presence of midline shift at diagnosis remained an independent prognostic factor influencing survival among good performance status patients. While the role of decompressive surgery in this setting is likely of some benefit, the extent of this benefit remains to be defined.     

Radiochemotherapy in patients with primary glioblastoma comparing two temozolomide dose regimens

PURPOSE: To evaluate toxicity and outcomes in patients with primary glioblastoma (GB) treated with postoperative radiochemotherapy (RCHT) with temozolomide (TMZ) comparing two dose regimens. METHODS AND MATERIALS: A total of 160 patients with histologically confirmed GB were treated with postoperative RCHT with TMZ. Of the patients, 66 were female and 94 were male, with a median age of 60 years. After the primary diagnosis, a biopsy had been performed in 42 patients; a subtotal and total resection was conducted in 66 and 52 patients. Postoperative radiotherapy was applied with a median dose of 60 Gy with a median fractionation of 5 x 2Gy/week. Concomitant TMZ was prescribed at 50 mg/m(2) in 123 patients (Group A) and at 75 mg/m(2) in 37 patients (Group B). Patients were followed in 3-months intervals, with a median follow-up of 13 months. RESULTS: Overall survival (OS) rates in Group A vs. Group B were 67% and 79% at 1 year and 43% vs. 49% at 2 years, respectively (p = 0.69). Progression-free survival was 49% vs. 54% at 1 year and 22% vs. 29% at 2 years (p = 0.31). Hematologic toxicity was not statistically significant over the 6-week RCHT period except for a significant decrease in platelets during Week 6 (p = 0.01) in Group B. CONCLUSIONS: Overall survival seems to be comparable in both groups, although longer follow-up and a larger group of patients are needed to corroborate these results. Lower dosing of TMZ also is associated with a more beneficial toxicity profile.     

miRNA在恶性血液病中的研究进展

 MicroRNA（miRNA）是一类小的非编码RNA,miRNA在转录水平介导目的基因mRNA的切割与翻译抑制,调控基因表达,调节细胞的增生、分化和凋亡,参与白血病、淋巴瘤的发生和进展。近年来,发现miRNA与恶性血液病的发生进展有关。通过不同的检测方法研究miRNA在恶性血液病中的表达,可对白血病、恶性淋巴瘤的发病机制更进一步了解,是诊断治疗和预后判断的重要指标。     

Postoperative treatment of primary glioblastoma multiforme with radiation and concomitant temozolomide in elderly patients

PURPOSE: To evaluate efficacy and toxicity in elderly patients with glioblastoma multiforme (GBM) treated with postoperative radiochemotherapy with temozolomide (TMZ). PATIENTS AND METHODS: Forty-three patients aged 65 years or older were treated with postoperative with radiochemotherapy using TMZ for primary GBM. Median age at primary diagnosis was 67 years; 14 patients were female, 29 were male. A complete surgical resection was performed in 12 patients, subtotal resection in 17 patients, and biopsy only in 14 patients. Radiotherapy was applied with a median dose of 60 Gy, in a median fractionation of 5x2 Gy/wk. Thirty-five patients received concomitant TMZ at 50 mg/m2, and in 8 patients 75 mg/m2 of TMZ was applied. Adjuvant cycles of TMZ were prescribed in 5 patients only. RESULTS: Median overall survival was 11 months in all patients; the actuarial overall survival rate was 48% at 1 year and 8% at 2 years. Median overall survival was 18 months after complete resection, 16 months after subtotal resection, and 6 months after biopsy only. Median progression-free survival was 4 months; the actuarial progression-free survival rate was 41% at 6 months and 18% at 12 months. Radiochemotherapy was well tolerated in most patients and could be completed without interruption in 38 of 43 patients. Four patients developed hematologic side effects greater than Common Terminology Criteria Grade 2, which led to early discontinuation of TMZ in 1 patient. CONCLUSIONS: Radiochemotherapy is safe and effective in a subgroup of elderly patients with GBM and should be considered in patients without major comorbidities.     

Identification of therapy-sensitive and therapy-resistant neuroblastoma subtypes in stages III, IVs and IV

The aim was to present a new model of risk stratification with high predictive sensitivity for non-localized neuroblastomas (NBs). "MYCN amplification", "unfavorable histology of the International Neuroblastoma Pathology Classification (INPC) system" and "low Ha-ras/trk A expression" could be defined as an independent predictor for high-risk NBs. A risk stratification flow chart was applied to 103 advanced NBs in which all three factors were examined and 69 were grouped as high-risk NBs of which 38 patients died. The predictive sensitivity for poor patient outcome was 86%, which included 38 of the 44 total deaths in this analysis. Using the number of the three independent risk factors in each tumor, the 69 high-risk NBs were classified into three subgroups. NBs with the three risk factors (triple risk) represented the most aggressive character and survival of the affected patients was only 10% ("therapy-resistant NBs"). Survivals of the patients with NBs possessed the two (double) risk factors or the one (single) risk factor were 29% and 66%, respectively. This stratification also elucidated a subgroup in which patient survival was 90% ("therapy-sensitive"). There were 21 NBs with "high Ha-ras/trk A expression", "favorable INPC histology" and "unamplified MYCN" (no risk NBs). Among the four subgroups without a risk factor, with a single risk factor, with double risk and with triple risk, Kaplan-Meier analysis showed a significant difference in NB patient outcome (p<0.0001). Risk stratification might improve the therapeutic efficacy for the high-risk NBs and might decrease therapy-related sequelae in the lower risk NBs.     

Racial/ethnic differences in survival among elderly patients with a primary glioblastoma

Background Few studies have assessed racial/ethnic differences in survival after primary glioblastoma diagnosis. We investigate these differences, incorporating information on White, Hispanics and Asians, as well as White, non-Hispanics and Blacks, among elderly individuals with a primary glioblastoma utilizing the population-based Surveillance, Epidemiology and End Results (SEER) Program-Medicare linked database. Methods A total of 1,530 individuals diagnosed > = 66 years of age from 6/1/91 to 12/31/99 in the SEER data were linked with Medicare information from 1/1/91 to 12/31/01. All individuals had Medicare Parts A and B and were non-HMO for 6 months before and 12 months after diagnosis to gather pre-diagnosis co-morbidities and post-diagnosis first course of treatment. Survival differences by race/ethnicity and by race/ethnicity stratified by treatment type and/or median household income were examined using Kaplan–Meier and multivariable Cox proportional hazards models. Results Significant racial/ethnic differences existed between White, non-Hispanics and Blacks in marital status, income and SEER registry region for the entire US. In analysis limited to the West region, significant racial/ethnic differences existed for income only. Overall there were no differences in survival between White, non-Hispanics and Blacks, however, in analysis limited to the West region, Asians had a lower risk of death compared to White, non-Hispanics [HR = 0.67, 95% CI (0.43, 1.03)]. Asians who had multiple treatments also had a lower risk of death compared to White, non-Hispanics [HR = 0.65, 95% CI (0.41, 1.01)]. Conclusions Racial/ethnic differences in survival after primary glioblastoma diagnosis exist and may be partially explained by racial/ethnic differences in treatment and income. Dr Barnholtz-Sloan has now moved to a new institution, but this study was performed while she was at the H. Lee Moffitt Cancer Center and Research Institute     

A pilot study of primary temozolomide chemotherapy and deferred radiotherapy in elderly patients with glioblastoma

There is no standard of care for elderly patients (age ≥ 70 years) with newly diagnosed glioblastoma (GBM). In 15 consecutive patients (median age 79 years) treated with temozolomide (TMZ) (42 days on; 14 days off), median survival was 6 months (range 4–14 months). This pilot study suggests that low dose daily TMZ may represent an alternative and equally effective treatment to more traditionally administered radiotherapy.     

Targeting apoptosis pathways in glioblastoma

The treatment of glioblastoma remains a major challenge for clinicians since these highly aggressive brain tumors are relatively resistant towards radio- and chemotherapy. The pathways that control apoptosis are altered in glioblastoma cells leading to resistance towards apoptotic stimuli in general. In this review we describe the alterations affecting the p53 pathway, the BCL-2 protein family, the inhibitor of apoptosis proteins and several growth factor pathways involved in the regulation of programmed cell death and define possible targets for new therapies within these apoptotic pathways in glioblastomas. Moreover, we review strategies to target death receptor pathways, most notably to render the glioblastoma cells more susceptible towards this approach without enhancing toxicity in general. Most of the strategies targeting apoptosis in glioblastomas presented here are in a pre-clinical stage of development, however, they all share the ultimative goal to improve the outcome for glioblastoma patients.     

手术切除治疗巨大原发性肝癌的预后因素分析

目的 研究巨大原发性肝癌患者手术切除治疗后的预后影响因素,寻找改善巨大原发性肝癌患者预后的方法。方法 回顾性分析69例手术切除治疗的巨大原发性肝癌患者的临床资料,采用Cox回归模型对16个可能与患者预后有关的因素进行统计学分析。结果 58例患者获得随访,随访患者的l、3、5年生存率分别为58.2％、31.4％和12.3％。单因素分析的结果显示,有无肝内转移、有无血管侵犯、肝硬化程度和是否行根治性切除与巨大原发性肝癌手术切除治疗后患者的预后有关（均P＜0.05）。Cox多因素回归分析的结果显示,肝硬化程度、有无肝内转移和是否行根治性切除是影响巨大原发性肝癌患者手术切除治疗后预后的独立因素（均P＜0.05）。结论 积极行手术切除是治疗巨大原发性肝癌的主要措施,其预后取决于是否伴有肝内转移、肝硬化程度和是否行根治性切除。     

Real-time PCR assay based on the differential expression of microRNAs and protein-coding genes for molecular classification of formalin-fixed paraffin embedded medulloblastomas

Background

Medulloblastoma has recently been found to consist of 4 molecularly and clinically distinct subgroups: WNT, Sonce hedgehog (SHH), Group 3, and Group 4. Deregulated microRNA expression is known to contribute to pathogenesis and has been shown to have diagnostic and prognostic potential in the classification of various cancers.

Methods

Molecular subgrouping and microRNA expression analysis of 44 frozen and 59 formalin-fixed paraffin embedded medulloblastomas from an Indian cohort were carried out by real-time RT-PCR assay.

Results

The differential expression of 9 microRNAs in the 4 molecular subgroups was validated in a set of 101 medulloblastomas. The tumors in the WNT subgroup showed significant (P < .0001) overexpression of miR-193a-3p, miR-224, miR-148a, miR-23b, and miR-365. Reliable classification of medulloblastomas into the 4 molecular subgroups was obtained using a set of 12 protein-coding genes and 9 microRNAs as markers in a real-time RT-PCR assay with an accuracy of 97% as judged by the Prediction Analysis of Microarrays. Age at diagnosis, histology, gender-related incidence, and the relative survival rates of the 4 molecular subgroups in the present Indian cohort were found to be similar to those reported for medulloblastomas from the American and European subcontinent. Non-WNT, non–SHH medulloblastomas underexpressing miR-592 or overexpressing miR-182 were found to have significantly inferior survival rates, indicating utility of these miRNAs as markers for risk stratification.

Conclusions

The microRNA based real-time PCR assay is rapid, simple, inexpensive, and useful for molecular classification and risk stratification of medulloblastomas, in particular formalin-fixed paraffin embedded tissues, wherein the expression profile of protein-coding genes is often less reliable due to RNA fragmentation.     

Possible explanation of radioresistance of glioblastoma in situ

The response of human glioblastoma to radiation was studied in the logarithmic phase and in the plateau phase of growth, and was compared with those of HeLa S3 irradiated under identical conditions. There was no major difference in the in vitro survival curve parameters between glioblastoma and HeLa in the logarithmic growth phase. However, the surviving fractions for glioblastoma with radiation doses in the range used clinically were higher not only when irradiated in the logarithmic growth phase, but also when subcultured 6 hours after irradiation in the plateau phase, than those for HeLa treated under identical conditions. This suggests that the relatively low cure rate of glioblastoma can be partially explained by the intrinsic radiosensitivity in the logarithmic growth phase and by a high surviving fraction for cells irradiated in the plateau phase.     

Subcurative radiation significantly increases cell proliferation,invasion, and migration of primary glioblastoma multiforme in vivo

Tumor cell proliferation, infiltration, migration, and neovascularization are known causes of treatment resistance in glioblastoma multiforme(GBM). The purpose of this study was to determine the effect of radiation on the growth characteristics of primary human GBM developed in a nude rat. Primary GBM cells grown from explanted GBM tissues were implanted orthotopically in nude rats. Tumor growth was confirmed by magnetic resonance imaging on day 77(baseline) after implantation. The rats underwent irradiation to a dose of 50 Gy delivered subcuratively on day 84 postimplantation(n = 8), or underwent no radiation(n = 8). Brain tissues were obtained on day 112(nonirradiated) or day 133(irradiated). Immunohistochemistry was performed to determine tumor cell proliferation(Ki-67) and to assess the expression of infiltration marker(matrix metalloproteinase-2, MMP-2) and cell migration marker(CD44). Tumor neovascularization was assessed by microvessel density using von-Willebrand factor(vWF) staining. Magnetic resonance imaging showed well-developed, infiltrative tumors in 11 weeks postimplantation. The proportion of Ki-67-positive cells in tumors undergoing radiation was(71 ± 15)% compared with(25 ± 12)% in the nonirradiated group(P = 0.02). The number of MMP-2-positive areas and proportion of CD44-positive cells were also high in tumors receiving radiation, indicating great invasion and infiltration. Microvessel density analysis did not show a significant difference between nonirradiated and irradiated tumors. Taken together, we found that subcurative radiation significantly increased proliferation, invasion, and migration of primary GBM. Our study provides insights into possible mechanisms of treatment resistance following radiation therapy for GBM.     

人脑胶质母细胞瘤微循环模式观察

背景与目的:胶质母细胞瘤是一种以微血管增生为特征的高度血管化的异生组织,但现有的抗血管生成药物对胶质瘤的治疗效果却不尽如人意。本文通过分析胶质母细胞瘤的微循环模式,为更好地理解胶质母细胞瘤的微循环构筑和靶向肿瘤养分供给系统的治疗提供新的视角。方法:采用CD34-PAS双重染色技术分析胶质母细胞瘤的微循环构筑。结果:胶质母细胞瘤的微血管密度大于正常脑组织,两者差异有统计学意义(P<0.001)。胶质母细胞瘤中存在血管内皮依赖性血管、肿瘤细胞依赖性血管、细胞外基质依赖性血管和马赛克血管4种微循环模式。结论:胶质母细胞瘤的微循环模式具有异质性。