The prognostic value of MGMT promoter methylation in Glioblastoma multiforme: a meta-analysis

A 35-gene signature discriminates between rapidly- and slowly-progressing glioblastoma multiforme and predicts survival in known subtypes of the cancer

BACKGROUND

Gene expression can be employed for the discovery of prognostic gene or multigene signatures cancer. In this study, we assessed the prognostic value of a 35-gene expression signature selected by pathway and machine learning based methods in adjuvant therapy-linked glioblastoma multiforme (GBM) patients from the Cancer Genome Atlas.

METHODS

Genes with high expression variance was subjected to pathway enrichment analysis and those having roles in chemoradioresistance pathways were used in expression-based feature selection. A modified Support Vector Machine Recursive Feature Elimination algorithm was employed to select a subset of these genes that discriminated between rapidly-progressing and slowly-progressing patients.

RESULTS

Survival analysis on TCGA samples not used in feature selection and samples from four GBM subclasses, as well as from an entirely independent study, showed that the 35-gene signature discriminated between the survival groups in all cases (p<0.05) and could accurately predict survival irrespective of the subtype. In a multivariate analysis, the signature predicted progression-free and overall survival independently of other factors considered.

CONCLUSION

We propose that the performance of the signature makes it an attractive candidate for further studies to assess its utility as a clinical prognostic and predictive biomarker in GBM patients. Additionally, the signature genes may also be useful therapeutic targets to improve both progression-free and overall survival in GBM patients.

BCAT1 is a New MR Imaging-related Biomarker for Prognosis Prediction in IDH1-wildtype Glioblastoma Patients

Isocitrate dehydrogenase 1 (IDH1)-wildtype glioblastoma (GBM) has found to be accompanied with increased expression of branched-chain amino acid trasaminase1 (BCAT1), which is associated with tumor growth and disease progression. In this retrospective study, quantitative RT-PCR, immunohistochemistry, and western blot were performed with GBM patient tissues to evaluate the BCAT1 level. Quantitative MR imaging parameters were evaluated from DSC perfusion imaging, DWI, contrast-enhanced T1WI and FLAIR imaging using a 3T MR scanner. The level of BCAT1 was significantly higher in IDH1-wildtype patients than in IDH1-mutant patients obtained in immunohistochemistry and western blot. The BCAT1 level was significantly correlated with the mean and 95^th percentile-normalized CBV as well as the mean ADC based on FLAIR images. In addition, the 95^th percentile-normalized CBV from CE T1WI also had a significant correlation with the BCAT1 level. Moreover, the median PFS in patients with BCAT1 expression <100 was longer than in those with BCAT1 expression ≥100. Taken together, we found that a high BCAT1 level is correlated with high CBV and a low ADC value as well as the poor prognosis of BCAT1 expression is related to the aggressive nature of GBM.

C. Fung K, Rundle-Thiele D, Martin JH. Persistence of DNA adducts, hypermutation and acquisition of cellular resistance to alkylating agents in glioblastoma

Glioblastoma is a lethal form of brain tumour usually treated by surgical resection followed by radiotherapy and an alkylating chemotherapeutic agent. Key to the success of this multimodal approach is maintaining apoptotic sensitivity of tumour cells to the alkylating agent. This initial treatment likely establishes conditions contributing to development of drug resistance as alkylating agents form the O6-methylguanine adduct. This activates the mismatch repair (MMR) process inducing apoptosis and mutagenesis. This review describes key juxtaposed drivers in the balance between alkylation induced mutagenesis and apoptosis. Mutations in MMR genes are the probable drivers for alkylation based drug resistance. Critical to this interaction are the dose-response and temporal interactions between adduct formation and MMR mutations. The precision in dose interval, dose-responses and temporal relationships dictate a role for alkylating agents in either promoting experimental tumour formation or inducing tumour cell death with chemotherapy. Importantly, this resultant loss of chemotherapeutic selective pressure provides opportunity to explore novel therapeutics and appropriate combinations to minimise alkylation based drug resistance and tumour relapse.

A relative increase in circulating platelets following chemoradiation predicts for poor survival of patients with glioblastoma

Background

Thrombocytosis is triggered by and promotes tumor growth. The relationship between the change in circulating platelets after chemoradiation therapy (CRT) or adjuvant temozolomide (TMZ) and survival in glioblastoma remains unclear. We hypothesized that an increase in platelets after these treatments would be predictive of a shorter survival.

Methods

We retrospectively reviewed data on 122 patients with newly diagnosed, pathologically proven glioblastoma who had been treated with surgery, followed by CRT and adjuvant TMZ, from 2007 to 2016. The association between the changes in blood count levels and survival was analyzed by the log-rank test. To adjust for confounding, we performed a multivariate analysis using known prognostic co-variates.

Results

Patients were dichotomized on the basis of the relative change in platelets after CRT from the baseline: ≤30% increase, low (n = 101) vs >30% increase, high (n = 12). The median survival for high vs. low platelets were 11 vs 28 months (p = 0.0062). No significant survival differences were observed on the basis of platelet changes during adjuvant TMZ. Similarly, changes in lymphocyte counts were not significantly prognostic. On multivariate analysis, MGMT, performance status, and an increase in platelets after CRT were significantly associated with survival (HR for platelets, 4.5; 95% confidence interval, 1.6-12.6).

Conclusions

Increased platelet counts after CRT are predictive of poor survival in glioblastoma. The effect is platelet specific and does not reflect bone marrow changes, as lymphocyte changes were not significantly prognostic. These results suggest an interaction between platelets and tumor aggressiveness. Thus, platelets serve as a novel, minimally invasive liquid biopsy for predicting outcome.

Residual Deep Convolutional Neural Network Predicts MGMT Methylation Status

Predicting methylation of the O6-methylguanine methyltransferase (MGMT) gene status utilizing MRI imaging is of high importance since it is a predictor of response and prognosis in brain tumors. In this study, we compare three different residual deep neural network (ResNet) architectures to evaluate their ability in predicting MGMT methylation status without the need for a distinct tumor segmentation step. We found that the ResNet50 (50 layers) architecture was the best performing model, achieving an accuracy of 94.90% (+/- 3.92%) for the test set (classification of a slice as no tumor, methylated MGMT, or non-methylated). ResNet34 (34 layers) achieved 80.72% (+/- 13.61%) while ResNet18 (18 layers) accuracy was 76.75% (+/- 20.67%). ResNet50 performance was statistically significantly better than both ResNet18 and ResNet34 architectures (p < 0.001). We report a method that alleviates the need of extensive preprocessing and acts as a proof of concept that deep neural architectures can be used to predict molecular biomarkers from routine medical images.

PiiL: visualization of DNA methylation and gene expression data in gene pathways

Background

DNA methylation is a major mechanism involved in the epigenetic state of a cell. It has been observed that the methylation status of certain CpG sites close to or within a gene can directly affect its expression, either by silencing or, in some cases, up-regulating transcription. However, a vertebrate genome contains millions of CpG sites, all of which are potential targets for methylation, and the specific effects of most sites have not been characterized to date. To study the complex interplay between methylation status, cellular programs, and the resulting phenotypes, we present PiiL, an interactive gene expression pathway browser, facilitating analyses through an integrated view of methylation and expression on multiple levels.

Results

PiiL allows for specific hypothesis testing by quickly assessing pathways or gene networks, where the data is projected onto pathways that can be downloaded directly from the online KEGG database. PiiL provides a comprehensive set of analysis features that allow for quick and specific pattern searches. Individual CpG sites and their impact on host gene expression, as well as the impact on other genes present in the regulatory network, can be examined. To exemplify the power of this approach, we analyzed two types of brain tumors, Glioblastoma multiform and lower grade gliomas.

Conclusion

At a glance, we could confirm earlier findings that the predominant methylation and expression patterns separate perfectly by mutations in the IDH genes, rather than by histology. We could also infer the IDH mutation status for samples for which the genotype was not known. By applying different filtering methods, we show that a subset of CpG sites exhibits consistent methylation patterns, and that the status of sites affect the expression of key regulator genes, as well as other genes located downstream in the same pathways.

PiiL is implemented in Java with focus on a user-friendly graphical interface. The source code is available under the GPL license from https://github.com/behroozt/PiiL.git.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3950-9) contains supplementary material, which is available to authorized users.

DNA methylation profiles in cancer diagnosis and therapeutics

Cancer initiation and proliferation is regulated by both epigenetic and genetic events with epigenetic modifications being increasingly identified as important targets for cancer research. DNA methylation catalyzed by DNA methyltransferases (DNMTs) is one of the essential epigenetic mechanisms that control cell proliferation, apoptosis, differentiation, cell cycle, and transformation in eukaryotes. Recent progress in epigenetics revealed a deeper understanding of the mechanisms of tumorigenesis and provided biomarkers for early detection, diagnosis, and prognosis in cancer patients. Although DNA methylation biomarker possesses potential contributing to precision medicine, there are still limitations to be overcome before it reaches clinical setting. Hence, the current status of DNA methylation biomarkers was reviewed and the future use in clinic was also predicted.

Patterns of care and outcomes in gliosarcoma: an analysis of the National Cancer Database

OBJECTIVE The authors compared presenting characteristics and survival for patients with gliosarcoma (GS) and glioblastoma (GBM). Additionally, they performed a survival analysis for patients who underwent GS treatments with the hypothesis that trimodality therapy (surgery followed by radiation and chemotherapy) would be superior to nontrimodality therapy (surgery alone or surgery followed by chemotherapy or radiation). METHODS Adults diagnosed with GS and GBM between the years 2004 and 2013 were queried from the National Cancer Database. Chi-square analysis was used to compare presenting characteristics. Kaplan-Meier, Cox regression, and propensity score analyses were employed for survival analyses. RESULTS In total, data from 1102 patients with GS and 36,658 patients with GBM were analyzed. Gliosarcoma had an increased rate of gross-total resection (GTR) compared with GBM (19% vs 15%, p < 0.001). Survival was not different for patients with GBM (p = 0.068) compared with those with GS. After propensity score analysis for GS, patients receiving trimodality therapy (surgery followed by radiation and chemotherapy) had improved survival (12.9 months) compared with those not receiving trimodality therapy (5.5 months). In multivariate analysis, GTR, female sex, fewer comorbidities, trimodality therapy, and age < 65 years were associated with improved survival. There was a trend toward improved survival with MGMT promoter methylation (p = 0.117). CONCLUSIONS In this large registry study, there was no difference in survival in patients with GBM compared with GS. Among GS patients, trimodality therapy significantly improved survival compared with nontrimodality therapy. Gross-total resection also improved survival, and there was a trend toward increased survival with MGMT promoter methylation in GS. The major potential confounder in this study is that patients with poor functional status may not have received aggressive radiation or chemotherapy treatments, leading to the observed outcome. This study should be considered hypothesis-generating; however, due to its rarity, conducting a clinical trial with GS patients alone may prove difficult.

Prior malignancies in patients harboring glioblastoma: an institutional case-study of 2164 patients

More patients are surviving long-term following a cancer diagnosis and as such are at risk for second malignancies. As the most common primary brain tumor, glioblastoma (GBM) will not infrequently occur in this population. No study has examined the incidence of prior cancer (PC) in patients harboring GBM. Here we evaluate the epidemiological features, as well as the molecular and clinical characteristics of GBM as a second cancer. Utilizing a web-based cancer data management system at our institution, we identified 2164 patients harboring GBM from 2007 to 2014. We collected baseline demographic, molecular, and clinical data. Univariate analysis was performed to compare the cohort of GBM patients with and without PC diagnosis. Survival differences were analyzed with Kaplan-Meier and log-rank testing. A Cox-proportional hazards model was fit for multivariable analysis. 170 patients (7.9%) harboring GBM had a PC diagnosis. The median interval between diagnoses was 79 months. The most common pathologies were breast (18.8%) and prostate (18.8%) cancer. Patients with a PC were older at the time of GBM diagnosis than those without PC (66 vs. 59 years, p < 0.001) and were more likely to be white (88.2 vs. 72.8%, p < 0.001). Patients with PC were more likely to harbor an EGFR (20 vs. 12.3%, p < 0.001) or MGMT mutation (17.6 vs. 11.6%, p < 0.001). Median survival was 13 months in the PC cohort and 15 months in the cohort without PC (p = NS). Age, KPS, and diagnosis year were the only factors which influenced outcome in multivariable analysis. Patients who develop GBM following a prior malignancy constitute ~8% of patients with GBM. Despite significant molecular differences these two cohorts appear to have a similar overall prognosis and clinical course. Thus, whether or not a patient harbors a malignancy prior to diagnosis of GBM should not exclude him or her from aggressive treatment or for consideration of novel investigational therapies.

MRI texture features as biomarkers to predict MGMT methylation status in glioblastomas

Purpose:

Imaging biomarker research focuses on discovering relationships between radiological features and histological findings. In glioblastoma patients, methylation of the O⁶-methylguanine methyltransferase (MGMT) gene promoter is positively correlated with an increased effectiveness of current standard of care. In this paper, the authors investigate texture features as potential imaging biomarkers for capturing the MGMT methylation status of glioblastoma multiforme (GBM) tumors when combined with supervised classification schemes.

Methods:

A retrospective study of 155 GBM patients with known MGMT methylation status was conducted. Co-occurrence and run length texture features were calculated, and both support vector machines (SVMs) and random forest classifiers were used to predict MGMT methylation status.

Results:

The best classification system (an SVM-based classifier) had a maximum area under the receiver-operating characteristic (ROC) curve of 0.85 (95% CI: 0.78–0.91) using four texture features (correlation, energy, entropy, and local intensity) originating from the T2-weighted images, yielding at the optimal threshold of the ROC curve, a sensitivity of 0.803 and a specificity of 0.813.

Conclusions:

Results show that supervised machine learning of MRI texture features can predict MGMT methylation status in preoperative GBM tumors, thus providing a new noninvasive imaging biomarker.

Multidrug resistance in glioblastoma stem-like cells: Role of the hypoxic microenvironment and adenosine signaling

Glioblastoma multiforme (GBM) is considered the most common and aggressive tumour of the central nervous system and is characterized for being highly chemoresistant. This property is mainly due to the activation of Multiple Drug Resistance (MDR) mechanisms that protect cancer cells from structurally and morphologically different drugs. Overexpression and increased ABC transporters activity is one of the most important MDR mechanisms at the clinical level, and both its expression and activity are elevated in GBM cells. Within the tumour, there is a subpopulation called glioblastoma stem-like cells (GSCs), which due to its high tumourigenic capacity and chemoresistance, have been postulated as the main responsible for tumour recurrence. The GSCs inhabit hypoxic tumour zones, niches that apart from maintaining and promoting stem phenotype have also been correlated with high chemoresistance. Of the signalling pathways activated during hypoxia, purinergic signalling has been highly associated to the induction of MDR mechanisms. Through its receptors, the nucleoside adenosine has been shown to promotes the chemoresistance mediated by ABC transporters. Therefore, targeting its components is a promising alternative for GBM treatment. In this review, we will discuss chemoresistance in GSCs and the effect of the hypoxic microenvironment and adenosine on MDR mechanisms.

The effect of postoperative infection on survival in patients with glioblastoma

OBJECTIVE Glioblastoma is a primary glial neoplasm with a median survival of approximately 1 year. There are anecdotal reports that postoperative infection may confer a survival advantage in patients with glioblastoma. However, only a few case reports in the literature, along with 2 retrospective cohort studies, show some potential link between infection and prolonged survival in patients with glioblastoma. The objective of this study was to evaluate the effect of postoperative infection in patients with glioblastoma using a large national database. METHODS The linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database was searched to identify patients 66 years of age and older with glioblastoma, with and without infection, from 1997 to 2010. The primary outcome was survival after diagnosis. The statistical analysis was performed with a graphical representation using Kaplan-Meier curves, univariate analysis with the log-rank test, and multivariate analysis with proportional hazards modeling. RESULTS A total of 3784 patients with glioblastoma were identified from the database, and from these, 369 (9.8%) had postoperative infection within 1 month of surgery. In patients with glioblastoma who had an infection within 1 month of surgery, there was no significant difference in survival (median 5 months) compared with patients with no infection (median 6 months; p = 0.17). The study also showed that older age, increased Gagne comorbidity score, and having diabetes may be negatively associated with survival. CONCLUSIONS Infection after craniotomy within 1 month was not associated with a survival benefit in patients with glioblastoma.

Gliomatosis cerebri: A consensus summary report from the First International Gliomatosis cerebri Group Meeting, March 26-27, 2015, Paris, France

Gliomatosis cerebri (GC) is a universally fatal extensive and diffuse infiltration of brain parenchyma by a glial tumor. Many aspects of this phenomenon remain unknown. The First International Gliomatosis cerebri Group Meeting had the following goals: refine the clinical and radiologic diagnostic criteria for GC, suggest appropriate diagnostic procedures, standardize tissue manipulation for histologic and molecular characterization, and prioritize relevant preclinical projects. Also, general treatment recommendations were outlined for the pediatric population. Importantly, this meeting was the starting point for meaningful collaborative international research projects. This review is a consensus summary of discussions shared and conclusions derived from this meeting.

Akt and β-catenin contribute to TMZ resistance and EMT of MGMT negative malignant glioma cell line

Glioblastoma is one of the most lethal cancers in central nervous system, and some individual cells that cannot be isolated for surgical resection and also show treatment-resistance induce poor prognosis. Hence, in order to research these cells, we treated temozolomide (TMZ)-sensitive U87MG cells with 400μM TMZ in culture media for over 6months and established TMZ-resistant cell line designated as U87/TR. We detected the MGMT status through pyrosequencing and western blotting, and we also assessed the proliferation, migration, EMT-like changes and possible activated signaling pathways in U87/TR cells. Our results demonstrated that U87/TR was MGMT negative, which indicated that MGMT made no contribution for TMZ-resistance of U87/TR. And U87/TR cells displayed cell cycle arrest, higher capacity for migration and EMT-like changes including both phenotype and characteristic proteins. We also revealed that both β-catenin and the phosphorylation level of Akt and PRAS40 were increased in U87/TR, while we did not observe the phosphorylation of mTOR in U87/TR. It indicated that activation of Akt and Wnt/β-catenin pathways may be response for the chemo-resistance and increased invasion of U87/TR cells, and the phosphorylation of PRAS40 and inactivated mTOR may be related to cell cycle arrest in U87/TR cells.

Pediatric Gliomatosis Cerebri: A Review of 15 Years

Gliomatosis cerebri is a rare glial tumor that carries a poor prognosis. Seen in both adults and children, gliomatosis cerebri appears to differ in these populations as with adult versus pediatric glioblastoma. We present 10 children who either presented to the Weill Cornell Medical College or enrolled in the institution's Gliomatosis Cerebri International Registry alongside a cohort of 89 pediatric patients reported in the literature between 2000 and 2014. Age ranged from 4 months to 21 years, with a male to female ratio of 1.71. Median overall survival for patients in the registry cohort was 17 months (n = 10) and for the historic cohort was 13 months (n = 52). Overall survival was analyzed for the combined cohort and was significantly longer when presenting at age ≥ 10 (20 vs 10 months), for boys (18 vs 11 months), and with low-grade pathology (26.5 vs 12 months) but did not vary significantly by treatment approach.

IDH-Mutation Is a Weak Predictor of Long-Term Survival in Glioblastoma Patients

BACKGROUND

A very small proportion of patients diagnosed with glioblastoma (GBM) survive more than 3 years. Isocitrate dehydrogenase 1 or 2 (IDH1/2) mutations define a small subgroup of GBM patients with favourable prognosis. However, it remains controversial whether long-term survivors (LTS) are found among those IDH1/2 mutated patients.

METHODS

We retrospectively analyzed 207 GBM patients followed at Lariboisière Hospital (Paris) between 2005 and 2010. Clinical parameters were obtained from medical records. Mutations of IDH1/2 were analyzed in these patients, by immunohistochemistry for the R132H mutation of IDH1 and by high-resolution melting-curve analysis, followed by Sanger sequencing for IDH1 and IDH2 exon 4 mutations. Mutation rates in LTS and non-LTS groups were compared by Chi square Pearson test.

RESULTS

Seventeen patients with survival >3 years were identified (8.2% of the total series). The median overall survival in long-term survivors was 4.6 years. Subgroup analysis found that the median age at diagnosis was significantly higher for non long-term survivors (non-LTS) compared to LTS (60 versus 51 years, p <0.03). The difference in the rate of IDH mutation between non-LTS and LTS was statistically not significant (1.16% versus 5.9%, p = 0.144). Among LTS, 10 out of 16 tumors presented a methylation of MGMT promoter.

CONCLUSIONS

This study confirms that long-term survival in GBM patients is if at all only weakly correlated to IDH-mutation.

MGMT promoter methylation and glioblastoma: a comparison of analytical methods and of tumor specimens

It is already well known that hypermethylation of the O6-methylguanine DNA methyltransferase (MGMT) gene promoter is a predictive biomarker of response to temozolomide treatment and of favorable outcomes in terms of overall survival (OS) and progression-free survival (PFS) in glioblastoma (GBM) patients. Nevertheless, MGMT methylation status has not currently been introduced into routine clinical practice, as the choice of the ideal technique and tissue sample specimen is still controversial. The aim of this study was to compare 2 analytical methods, methylation-specific polymerase chain reaction (MSP) and pyrosequencing (PSQ), and their use on 2 different tissue type samples, snap-frozen and formalin-fixed paraffin-embedded (FFPE), obtained from a single-center and uniformly treated cohort of 46 GBM patients. We obtained methylation data from all frozen tissues, while no results were obtained for 5 FFPE samples. The highest concordance for methylation was found on frozen tissues (88.5%, 23/26 samples), using PSQ (76.7%, 23/30 samples). Moreover, we confirmed that OS and PFS for patients carrying methylation of the MGMT promoter were longer than for patients with an unmethylated promoter. In conclusion, we considered MSP a limited technique for FFPE tissues due to the high risk of false-positive results; in contrast, our data indicated PSQ as the most powerful method to stratify methylated/unmethylated patients as it allows reaching quantitative results with high sensitivity and specificity. Furthermore, frozen tumor tissues were shown to be the best specimens for MGMT methylation analysis, due to the low DNA degradation and homogeneity in methylation throughout the tumor.

Retrospective analysis of bevacizumab in combination with fotemustine in chinese patients with recurrent glioblastoma multiforme

The aim of this study was to assess the activity and safety of bevacizumab (BEV) and fotemustine (FTM) for the treatment of recurrent glioblastoma multiforme (GBM) patients and explore the potential prognostic parameters on survival. This study retrospectively analyzed all patients with GBM who were treated with at least one cycle of BEV and FTM from July 2010 to October 2012. A total of 176 patients with recurrent GBM were enrolled. The response rate and disease control rate were 46.6% and 90.9%, respectively. A 6-month PFS rate of 33.3% (95% CI: 26.5%–40.3%) and a median PFS of 5.0 (95% CI: 2.4–7.5) months were observed. The median OS was 8.0 (95% CI: 6.7–9.2) months. Multivariate analysis showed that risk factors with a significant influence on the PFS of all patients were Karnofsky Performance Status (KPS) (≥70 versus <70, HR = 0.53, 95% CI: 0.39–0.73, and P = 0.01) and MGMT status (methylated versus unmethylated, HR = 0.69, 95% CI: 0.52–0.97, and P = 0.04). The most common treatment-related adverse events were fatigue, proteinuria, hypophonia, hypertension, thrombocytopenia, anemia, and neutropenia. In conclusion, combination of BEV with FTM is well tolerated and may derive some clinical benefits in recurrent GBM patients. Higher KPS and MGMT promoter hypermethylation were suggested to be associated with prolonged survival.

DNA methylation biomarkers: cancer and beyond

Biomarkers are naturally-occurring characteristics by which a particular pathological process or disease can be identified or monitored. They can reflect past environmental exposures, predict disease onset or course, or determine a patient's response to therapy. Epigenetic changes are such characteristics, with most epigenetic biomarkers discovered to date based on the epigenetic mark of DNA methylation. Many tissue types are suitable for the discovery of DNA methylation biomarkers including cell-based samples such as blood and tumor material and cell-free DNA samples such as plasma. DNA methylation biomarkers with diagnostic, prognostic and predictive power are already in clinical trials or in a clinical setting for cancer. Outside cancer, strong evidence that complex disease originates in early life is opening up exciting new avenues for the detection of DNA methylation biomarkers for adverse early life environment and for estimation of future disease risk. However, there are a number of limitations to overcome before such biomarkers reach the clinic. Nevertheless, DNA methylation biomarkers have great potential to contribute to personalized medicine throughout life. We review the current state of play for DNA methylation biomarkers, discuss the barriers that must be crossed on the way to implementation in a clinical setting, and predict their future use for human disease.

Ultrastructural characterization of primary cilia in pathologically characterized human glioblastoma multiforme (GBM) tumors

BACKGROUND

Primary cilia are non-motile sensory cytoplasmic organelles that are involved in cell cycle progression. Ultrastructurally, the primary cilium region is complex, with normal ciliogenesis progressing through five distinct morphological stages in human astrocytes. Defects in early stages of ciliogenesis are key features of astrocytoma/glioblastoma cell lines and provided the impetus for the current study which describes the morphology of primary cilia in molecularly characterized human glioblastoma multiforme (GBM) tumors.

METHODS

Seven surgically resected human GBM tissue samples were molecularly characterized according to IDH1/2 mutation status, EGFR amplification status and MGMT promoter methylation status and were examined for primary cilia expression and structure using indirect immunofluorescence and electron microscopy.

RESULTS

We report for the first time that primary cilia are disrupted in the early stages of ciliogenesis in human GBM tumors. We confirm that immature primary cilia and basal bodies/centrioles have aberrant ciliogenesis characteristics including absent paired vesicles, misshaped/swollen vesicular hats, abnormal configuration of distal appendages, and discontinuity of centriole microtubular blades. Additionally, the transition zone plate is able to form in the absence of paired vesicles on the distal end of the basal body and when a cilium progresses beyond the early stages of ciliogenesis, it has electron dense material clumped along the transition zone and a darkening of the microtubules at the proximal end of the cilium.

CONCLUSIONS

Primary cilia play a role in a variety of human cancers. Previously primary cilia structure was perturbed in cultured cell lines derived from astrocytomas/glioblastomas; however there was always some question as to whether these findings were a cell culture phenomena. In this study we confirm that disruptions in ciliogenesis at early stages do occur in GBM tumors and that these ultrastructural findings bear resemblance to those previously observed in cell cultures. This is the first study to demonstrate that defects in cilia expression and function are a true hallmark of GBM tumors and correlate with their unrestrained growth. A review of the current ultrastructural profiles in the literature provides suggestions as to the best possible candidate protein that underlies defects in the early stages of ciliogenesis within GBM tumors.

How our practice of histopathology, especially tumour pathology has changed in the last two decades: reflections from a major referral center in Pakistan

Continued advances in the field of histo-pathology (and cyto-pathology) over the past two decades have resulted in dramatic changes in the manner in which these disciplines are now practiced. This is especially true in the setting of a large university hospital where the role of pathologists as clinicians (diagnosticians), undergraduate and postgraduate educators, and researchers has evolved considerably. The world around us has changed significantly during this period bringing about a considerable change in our lifestyles and the way we live. This is the world of the internet and the world-wide web, the world of Google and Wikipedia, of Youtube and Facebook where anyone can obtain any information one desires at the push of a button. The practice of histo (and cyto) pathology has also evolved in line with these changes. For those practicing this discipline in a poor, developing country these changes have been breathtaking. This is an attempt to document these changes as experienced by histo (and cyto) pathologists practicing in the biggest center for Histopathology in Pakistan, a developing country in South Asia with a large (180 million) and ever growing population. The Section of Histopathology, Department of Pathology and Microbiology at the Aga Khan University Hospital (AKUH) in Karachi, Pakistan's largest city has since its inception in the mid-1980s transformed the way histopathology is practiced in Pakistan by incorporating modern methods and rescuing histopathology in Pakistan from the primitive and outdated groove in which it was stuck for decades. It set histopathology in Pakistan firmly on the path of modernity and change which are essential for better patient management and care through accurate and complete diagnosis and more recently prognostic and predictive information as well.

The prognostic value of phosphorylated AKT expression in non-small cell lung cancer: a meta-analysis

OBJECTIVES

Phosphorylated AKT (p-AKT), constitutive activation of AKT, is a potentially interesting prognostic marker and therapeutic target in non-small cell lung cancer (NSCLC). However, the available results of p-AKT expression in NSCLC are heterogeneous. Therefore, a meta-analysis of published researches investigating the prognostic relevance of p-AKT expression in patients with NSCLC was performed.

MATERIALS AND METHODS

A literature search via PubMed, EMBASE and CNKI (China National Knowledge Infrastructure) databases was conducted. Data from eligible studies were extracted and included into meta-analysis using a random effects model.

RESULTS

A total of 1049 patients from nine studies were included in the meta-analysis. Nine studies investigated the relationship between p-AKT expression and overall survival using univariate analysis, and five of these undertook multivariate analysis. The pooled hazard ratio (HR) for overall survival was 1.49 (95% confidence interval (CI): 1.01-2.20) by univariate analysis and 1.02 (95% CI: 0.54-1.95) by multivariate analysis.

CONCLUSION

Our study shows that positive expression of p-AKT is associated with poor prognosis in patients with NSCLC. However, adequately designed prospective studies need to perform.