MiRNA expression patterns predict survival in glioblastoma

<p>Abstract</p> <p>Background</p> <p>In order to define new prognostic subgroups in patients with glioblastoma a miRNA screen (> 1000 miRNAs) from paraffin tissues followed by a bio-mathematical analysis was performed.</p> <p>Methods</p> <p>35 glioblastoma patients treated between 7/2005 - 8/2008 at a single institution with surgery and postoperative radio(chemo)therapy were included in this retrospective analysis. For microarray analysis the febit biochip "Geniom^®Biochip MPEA homo-sapiens" was used. Total RNA was isolated from FFPE tissue sections and 1100 different miRNAs were analyzed.</p> <p>Results</p> <p>It was possible to define a distinct miRNA expression pattern allowing for a separation of distinct prognostic subgroups. The defined miRNA pattern was significantly associated with early death versus long-term survival (split at 450 days) (p = 0.01). The pattern and the prognostic power were both independent of the MGMT status.</p> <p>Conclusions</p> <p>At present, this is the first dataset defining a prognostic role of miRNA expression patterns in patients with glioblastoma. Having defined such a pattern, a prospective validation of this observation is required.</p

Evaluation of different biomarkers to predict individual radiosensitivity in an inter-laboratory comparison--lessons for future studies.

Radiotherapy is a powerful cure for several types of solid tumours, but its application is often limited because of severe side effects in individual patients. With the aim to find biomarkers capable of predicting normal tissue side reactions we analysed the radiation responses of cells from individual head and neck tumour and breast cancer patients of different clinical radiosensitivity in a multicentric study. Multiple parameters of cellular radiosensitivity were analysed in coded samples of peripheral blood lymphocytes (PBLs) and derived lymphoblastoid cell lines (LCLs) from 15 clinical radio-hypersensitive tumour patients and compared to age- and sex-matched non-radiosensitive patient controls and 15 lymphoblastoid cell lines from age- and sex- matched healthy controls of the KORA study. Experimental parameters included ionizing radiation (IR)-induced cell death (AnnexinV), induction and repair of DNA strand breaks (Comet assay), induction of yH2AX foci (as a result of DNA double strand breaks), and whole genome expression analyses. Considerable inter-individual differences in IR-induced DNA strand breaks and their repair and/or cell death could be detected in primary and immortalised cells with the applied assays. The group of clinically radiosensitive patients was not unequivocally distinguishable from normal responding patients nor were individual overreacting patients in the test system unambiguously identified by two different laboratories. Thus, the in vitro test systems investigated here seem not to be appropriate for a general prediction of clinical reactions during or after radiotherapy due to the experimental variability compared to the small effect of radiation sensitivity. Genome-wide expression analysis however revealed a set of 67 marker genes which were differentially induced 6 h after in vitro-irradiation in lymphocytes from radio-hypersensitive and non-radiosensitive patients. These results warrant future validation in larger cohorts in order to determine parameters potentially predictive for clinical radiosensitivity

Late toxicity grade in acutely radiosensitive (s) and non-radiosensitive (ns) patients suffering from head and neck cancer. Each patient is indicated with an identification number (ID).

<p>Matched pairs with lower late toxicity of the acute radiosensitive patients are indicated in yellow.</p

Dose-response relationship of Gamma-H2AX at different time points from two different centres (white boxes – centre C, hatched boxes – centre B).

<p>Each measured value corresponds to the n-fold change to the time point at 0 Gy after 24 hours. (a) Data for the PBLs: Box plots only include samples with an initial cell viability of higher than 80%. (b) Data for LCLs over all samples.</p

Results of the comparison between head and neck tumour (HN-Ca) and breast cancer patients (Ma-Ca) within a generalised estimating equations (GEE) analysis, adjusted for laboratory, irradiation dose and sensitivity group.

<p>Columns represent the assays, the target parameter names, the estimated parameter value, the standard error of the parameter estimate, the confidence intervals and the associated p-value for testing the significance of the parameter to the model. P-values less than 0.05 are considered significant (*). The estimator is a parameter that indicates the average value, on which the head and neck cancer patients have less or greater values compared to breast cancer patients.</p

Required number of samples per group (radiosensitive and non-radiosensitive, respectively) to detect a significant difference between both groups (power = 80%, significance level = 5%) for a given standard deviation and effect size.

<p>The calculations were reduced by the 2 endpoints of repairing after 15 and 60 minutes of 5Gy irradiation, since these points of time appear to need the lowest sample sizes. With regard to the standard deviation the minimal and maximal values from the original dataset for the two timeframes were selected.</p

Comparison between non-radiosensitive vs. radiosensitive patients for apoptosis and necrosis in each laboratory within the different dose rates.

<p>P values were determined by Mann-Whitney U test. The differences were statistically not relevant as indicated by the high p values >0.05.</p

Dose-response relationship of Olive tail moment (OTM) in PBLs at different time points.

<p>Data from two different centres E (white boxes) and D (hatched boxes) are presented. Comet assay of both laboratories revealed similar results by investigating OTM in PBLs directly after irradiation with 5 Gy and at different time points. Non-radiosensitive and radiosensitive individuals were not distinguishable.</p