title: Early dynamic transcriptomic changes during preoperative radiotherapy in patients with rectal cancer: a feasibility study.
abstract: OBJECTIVE
  To develop novel biomarkers of rectal radiotherapy, we measured gene expression profiles on biopsies taken before and during preoperative radiotherapy.
  
  
  METHODS
  Six patients presenting with a locally advanced rectal cancer (T>T2, N0/Nx, M0) eligible for preoperative radiotherapy (45 Gy in 25 fractions) were selected in a pilot study. Six tumor and 3 normal tissues biopsies were taken before and during radiotherapy, after a dose of 7.2 Gy at a median time of 1 h following irradiation (0:27-2:12). Tumor or normal tissue purity was assessed by a pathologist prior to RNA extraction. Mean RNA content was 23 μg/biopsy (14-37) before radiotherapy and 22.7 μg/biopsy (12-35) during radiotherapy. After RNA amplification, biopsies were analysed with 54K HG-U133A Plus 2.0 Affymetrix expression micro-arrays. Data were normalized according to MAS5 algorithm. A gene expression ratio was calculated as: (gene expression during radiotherapy - gene expression before radiotherapy)/gene expression before radiotherapy. Were selected genes that showed a ratio higher than ± 0.5 in all 6 patients.
  
  
  RESULTS
  Microarray analysis showed that preoperative radiotherapy significantly up-regulated 31 genes and down-regulated 6 genes. According to the Gene Ontology project classification, these genes are involved in protein metabolism (ADAMDEC1; AKAP7; CAPN5; CLIC5; CPE; CREB3L1; NEDD4L; RAB27A), ion transport (AKAP7; ATP2A3; CCL28; CLIC5; F2RL2; NEDD4L; SLC6A8), transcription (AKAP7; CREB3L1; ISX; PABPC1L; TXNIP), signal transduction (CAPN5; F2RL2; RAB27A; TNFRSF11A), cell adhesion (ADAMDEC1; PXDN; SPON1; S100A2), immune response (CCL28; PXDN; TNFRSF11A) and apoptosis (ITM2C; PDCD4; PVT1). Up-regulation of 3 genes (CCL28; CLIC5; PDCD4) was detected by 2 different probes and up-regulation of 2 genes (RAB27A; TXNIP) by 3 probes.
  
  
  CONCLUSIONS
  Micro-arrays can efficiently assess early transcriptomic changes during preoperative radiotherapy for rectal cancer, and may help better understand tumor radioresistance.
authors.affiliation: Department of Radiation Oncology, Institut de Cancérologie de l'Ouest René Gauducheau, 44800 Nantes-St-Herblain, France.
authors.forename: Stephane
authors.initials: S
authors.lastname: Supiot
authors.forename: Wilfried
authors.initials: W
authors.lastname: Gouraud
authors.forename: Loïc
authors.initials: L
authors.lastname: Campion
authors.forename: Pascal
authors.initials: P
authors.lastname: Jezéquel
authors.forename: Bruno
authors.initials: B
authors.lastname: Buecher
authors.forename: Josiane
authors.initials: J
authors.lastname: Charrier
authors.forename: Marie-Francoise
authors.initials: MF
authors.lastname: Heymann
authors.forename: Marc-Andre
authors.initials: MA
authors.lastname: Mahé
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Rio
authors.forename: Michel
authors.initials: M
authors.lastname: Chérel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D014408:Biomarkers, Tumor / Q000235:genetics*; D001706:Biopsy; D005240:Feasibility Studies; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects*; D006801:Humans; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D020411:Oligonucleotide Array Sequence Analysis; D010865:Pilot Projects; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000235:genetics* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor
keywords: CCL28; CLIC5; Carboxypeptidase E; Cell adhesion; Cell migration; PDCD4; Protein metabolism; RAB27A; SPON1; TXNIP