title: SLUG silencing increases radiosensitivity of melanoma cells in vitro.
abstract: BACKGROUND
  Melanoma radioresistance has been attributed to the presence of tumor cells with highly efficient DNA damage repair mechanisms. We examined the expression of genes involved in DNA damage repair and DNA damage sensing, and assessed their modulation by SLUG silencing, which is potentially capable of increasing radiosensitivity.
  
  
  METHODS
  Two melanoma cell lines (M14 and M79) were used to evaluate in vitro radiation-induced cytotoxicity before and after SLUG silencing. mRNA expression levels of BRCA1, ERCC1, DNA-PK, PARP, MGMT, ATM and TGM2 were determined by real-time RT-PCR, and protein expression levels of SLUG, caspase 3, p21, PUMA and pMAPK by Western blotting.
  
  
  RESULTS
  The cytotoxic effect of radiation was high in M14 and low in M79 cells. SLUG silencing increased the interference of radiation on cell cycle distribution and cell killing by 60 % and 80 % in M79 cells after a 2.4 Gy and 5 Gy radiation dose, respectively. It also led to a significant inhibition of expression of genes involved in DNA damage repair and DNA damage sensing in all cell lines maintained after radiation. An almost total inhibition was observed for TGM2, which is expressed at a high basal level in the most radioresistant cell line (M79). Protein expression of PUMA was induced by radiation and was enhanced after SLUG silencing.
  
  
  CONCLUSIONS
  Our results reveal a pivotal role of SLUG in regulating a cellular network involved in the response to DNA damage, and highlight the importance of TGM2 in radiosensitivity modulation. SLUG silencing appears to increase radiation sensitivity of the melanoma cells tested.
authors.affiliation: Biosciences Laboratory, IRCCS Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST), Via P. Maroncelli 40, Meldola, 47014, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Arienti
authors.forename: Anna
authors.initials: A
authors.lastname: Tesei
authors.forename: Silvia
authors.initials: S
authors.lastname: Carloni
authors.forename: Paola
authors.initials: P
authors.lastname: Ulivi
authors.forename: Antonino
authors.initials: A
authors.lastname: Romeo
authors.forename: Giulia
authors.initials: G
authors.lastname: Ghigi
authors.forename: Enrico
authors.initials: E
authors.lastname: Menghi
authors.forename: Anna
authors.initials: A
authors.lastname: Sarnelli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Parisi
authors.forename: Rosella
authors.initials: R
authors.lastname: Silvestrini
authors.forename: Wainer
authors.initials: W
authors.lastname: Zoli
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002453:Cell Cycle / Q000235:genetics / Q000528:radiation effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics / Q000528:radiation effects; D004249:DNA Damage / Q000235:genetics; D004307:Dose-Response Relationship, Radiation; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects*; D006801:Humans; D008545:Melanoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D000071250:Snail Family Transcription Factors; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors