title: Spotlight on differentially expressed genes in urinary bladder cancer.
abstract: BACKGROUND
  We previously identified common differentially expressed (DE) genes in bladder cancer (BC). In the present study we analyzed in depth, the expression of several groups of these DE genes.
  
  
  METHODS
  Samples from 30 human BCs and their adjacent normal tissues were analyzed by whole genome cDNA microarrays, qRT-PCR and Western blotting. Our attention was focused on cell-cycle control and DNA damage repair genes, genes related to apoptosis, signal transduction, angiogenesis, as well as cellular proliferation, invasion and metastasis. Four publicly available GEO Datasets were further analyzed, and the expression data of the genes of interest (GOIs) were compared to those of the present study. The relationship among the GOI was also investigated. GO and KEGG molecular pathway analysis was performed to identify possible enrichment of genes with specific biological themes.
  
  
  RESULTS
  Unsupervised cluster analysis of DNA microarray data revealed a clear distinction in BC vs. control samples and low vs. high grade tumors. Genes with at least 2-fold differential expression in BC vs. controls, as well as in non-muscle invasive vs. muscle invasive tumors and in low vs. high grade tumors, were identified and ranked. Specific attention was paid to the changes in osteopontin (OPN, SPP1) expression, due to its multiple biological functions. Similarly, genes exhibiting equal or low expression in BC vs. the controls were scored. Significant pair-wise correlations in gene expression were scored. GO analysis revealed the multi-facet character of the GOIs, since they participate in a variety of mechanisms, including cell proliferation, cell death, metabolism, cell shape, and cytoskeletal re-organization. KEGG analysis revealed that the most significant pathway was that of Bladder Cancer (p = 1.5×10(-31)).
  
  
  CONCLUSIONS
  The present work adds to the current knowledge on molecular signature identification of BC. Such works should progress in order to gain more insight into disease molecular mechanisms.
authors.affiliation: Laboratory of Virology, Medical School, University of Crete, Heraklion, Crete, Greece.
authors.forename: Apostolos
authors.initials: A
authors.lastname: Zaravinos
authors.forename: George I
authors.initials: GI
authors.lastname: Lambrou
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Volanis
authors.forename: Dimitris
authors.initials: D
authors.lastname: Delakas
authors.forename: Demetrios A
authors.initials: DA
authors.lastname: Spandidos
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D016000:Cluster Analysis; D030541:Databases, Genetic; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods*; D023281:Genomics; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D025341:Principal Component Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015996:Survival Rate; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: D012333:RNA, Messenger