Gene expression in oligodendroglial tumors
CELLULAR ONCOLOGY
Authors: Shaw, Elisabeth J.; Haylock, Brian; Husband, David; du Plessis, Daniel; Sibson, D. Ross; Warnke, Peter C.; Walker, Carol
Abstract
Oligodendroglial tumors with 1p/19q loss are more likely to be chemosensitive and have longer survival than those with intact 1p/19q, but not all respond to chemotherapy, warranting investigation of the biological basis of chemosensitivity. Gene expression profiling was performed using amplified antisense RNA from 28 oligodendroglial tumors treated with chemotherapy [26 serial stereotactic biopsy, 2 resection]. Expression of differentially expressed genes was validated by real-time PCR. Unsupervised hierarchical clustering showed clustering of multiple samples from the same case in 14/17 cases and identified subgroups associated with tumor grade and 1p/19q status. 176 genes were differentially expressed, 164 being associated with 1p/19q loss (86% not on 1p or 19q). 94 genes differed between responders and non-responders to chemotherapy; 12 were not associated with 1p/19q loss. Significant differential expression was confirmed in 11/13 selected genes. Novel genes associated with response to therapy included SSBP2, GFRA1, FAP and RASD1. IQGAP1, INA, TGIF1, NR2F2 and MYCBP were differentially expressed in oligodendroglial tumors with 1p/19q loss. Gene expression profiling using serial stereotactic biopsies indicated greater homogeneity within tumors than between tumors. Genes associated with 1p/19q status or response were identified warranting further elucidation of their role in oligodendroglial tumors.
GSTP1 Promoter Methylation is Associated with Recurrence in Early Stage Prostate Cancer
JOURNAL OF UROLOGY
Authors: Maldonado, Leonel; Brait, Mariana; Loyo, Myriam; Sullenberger, Lauren; Wang, Kevin; Peskoe, Sarah B.; Rosenbaum, Eli; Howard, Roslyn; Toubaji, Antoun; Albadine, Roula; Netto, George J.; Hoque, Mohammad O.; Platz, Elizabeth A.; Sidransky, David
Abstract
Purpose: Recurrent prostate cancer remains a major problem. Staging, grading and prostate specific antigen level at surgery are helpful but still imperfect predictors of recurrence. For this reason there is an imperative need for additional biomarkers that add to the prediction of currently used prognostic factors. Materials and Methods: We evaluated the extent of promoter methylation of genes previously reported as aberrantly methylated in prostate cancer (AIM1, APC, CCND2, GPX3, GSTP1, MCAM, RAR beta 2, SSBP2 and TIMP3) by quantitative fluorogenic methylation-specific polymerase chain reaction. We used cancer tissue from a nested case-control study of 452 patients surgically treated for prostate cancer. Recurrence cases and controls were compared and the association between methylation extent and recurrence risk was estimated by logistic regression adjusting for patient age at prostatectomy, prostatectomy year, stage, grade, surgical margins and preprostatectomy prostate specific antigen. All statistical tests were 2-sided with p <= 0.05 considered statistically significant. Results: The extent of GSTP1 methylation was higher in patients with recurrence than in controls (p = 0.01), especially patients with early disease, ie organ confined or limited extraprostatic extension (p = 0.001). After multivariate adjustment GSTP1 promoter methylation at or above the median was associated with an increased risk of recurrence, including in men with early disease (each p = 0.05). Conclusions: Greater GSTP1 promoter methylation in cancer tissue was independently associated with the risk of recurrence in patients with early prostate cancer. This suggests that GSTP1 promoter methylation may be a potential tissue based recurrence marker.