Background: Recurrent glioblastoma (GBM) is resistant to available treatments and continued growth of the tumor is inevitable; this process is facilitated by the expression of genes regulated by the Signal Transducer and Activator of Transcription (STAT) family of transcription factors, namely STAT5, active in the invasive rim of GBM tumors. Currently, there are no targeted therapies for recurrent GBM that increase the overall patient survival rate. This study aims to analyze the differential expression of genes regulated by STAT5 between primary and recurrent GBM.<br/>Methods: Analysis of whole exome and RNA sequencing were performed on matched bulk primary and multiple recurrent tumor samples from GBM patients who received the current standard care to determine significant changes in gene expression of STAT3/5 targets. <br/>Results: Statistical analysis reveals a decrease in Synaptotagmin 2 (SYT2) and Pleckstrin Homology Domain Containing A3 (PLEKHA3) at recurrence, previously identified as potential STAT5 targets. <br/>Conclusions: To get a better understanding of the roles of STAT5 in GBM recurrence, their downstream effects need to be better understood. The transcriptomic program initiated by STAT5 activation is distinct from that of STAT3 activation. The roles of STAT5 target genes in GBM are poorly characterized, so further research should focus on understanding the effects of altered expression of these genes as they relate to STAT3/5 in GBM recurrence.

The brain is a common site of metastatic disease in patients with breast cancer, which has few therapeutic options and dismal outcomes. The purpose of our study was to identify common and rare events that underlie breast cancer brain metastasis. We performed deep genomic profiling, which integrated gene copy number, gene expression and DNA methylation datasets on a collection of breast brain metastases. We identified frequent large chromosomal gains in 1q, 5p, 8q, 11q, and 20q and frequent broad-level deletions involving 8p, 17p, 21p and Xq. Frequently amplified and overexpressed genes included ATAD2, BRAF, DERL1, DNMTRB and NEK2A. The ATM, CRYAB and HSPB2 genes were commonly deleted and underexpressed. Knowledge mining revealed enrichment in cell cycle and G2/M transition pathways, which contained AURKA, AURKB and FOXM1. Using the PAM50 breast cancer intrinsic classifier, Luminal B, Her2+/ER negative, and basal-like tumors were identified as the most commonly represented breast cancer subtypes in our brain metastasis cohort. While overall methylation levels were increased in breast cancer brain metastasis, basal-like brain metastases were associated with significantly lower levels of methylation. Integrating DNA methylation data with gene expression revealed defects in cell migration and adhesion due to hypermethylation and downregulation of PENK, EDN3, and ITGAM. Hypomethylation and upregulation of KRT8 likely affects adhesion and permeability. Genomic and epigenomic profiling of breast brain metastasis has provided insight into the somatic events underlying this disease, which have potential in forming the basis of future therapeutic strategies.