title: Potentiation of inflammatory CXCL8 signalling sustains cell survival in PTEN-deficient prostate carcinoma.
abstract: BACKGROUND
  Inflammation and genetic instability are enabling characteristics of prostate carcinoma (PCa). Inactivation of the tumour suppressor gene phosphatase and tensin homolog (PTEN) is prevalent in early PCa. The relationship of PTEN deficiency to inflammatory signalling remains to be characterised.
  
  
  OBJECTIVE
  To determine how loss of PTEN functionality modulates expression and efficacy of clinically relevant, proinflammatory chemokines in PCa.
  
  
  METHODS
  Experiments were performed in established cell-based PCa models, supported by pathologic analysis of chemokine expression in prostate tissue harvested from PTEN heterozygous (Pten(+/-)) mice harbouring inactivation of one PTEN allele.
  
  
  METHODS
  Small interfering RNA (siRNA)- or small hairpin RNA (shRNA)-directed strategies were used to repress PTEN expression and resultant interleukin-8 (CXCL8) signalling, determined under normal and hypoxic culture conditions.
  
  
  METHODS
  Changes in chemokine expression in PCa cells and tissue were analysed by real-time polymerase chain reaction (PCR), immunoblotting, enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry; effects of chemokine signalling on cell function were assessed by cell cycle analysis, apoptosis, and survival assays.
  
  
  CONCLUSIONS
  Transient (siRNA) or prolonged (shRNA) PTEN repression increased expression of CXCL8 and its receptors, chemokine (C-X-C motif) receptor (CXCR) 1 and CXCR2, in PCa cells. Hypoxia-induced increases in CXCL8, CXCR1, and CXCR2 expression were greater in magnitude and duration in PTEN-depleted cells. Autocrine CXCL8 signalling was more efficacious in PTEN-depleted cells, inducing hypoxia-inducible factor-1 (HIF-1) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcription and regulating genes involved in survival and angiogenesis. Increased expression of the orthologous chemokine KC was observed in regions displaying atypical cytologic features in Pten(+/-) murine prostate tissue relative to normal epithelium in wild-type PTEN (Pten(WT)) glands. Attenuation of CXCL8 signalling decreased viability of PCa cells harbouring partial or complete PTEN loss through promotion of G1 cell cycle arrest and apoptosis. The current absence of clinical validation is a limitation of the study.
  
  
  CONCLUSIONS
  PTEN loss induces a selective upregulation of CXCL8 signalling that sustains the growth and survival of PTEN-deficient prostate epithelium.
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Maxwell
authors.forename: Jonathan
authors.initials: J
authors.lastname: Coulter
authors.forename: Steven M
authors.initials: SM
authors.lastname: Walker
authors.forename: Melanie
authors.initials: M
authors.lastname: McKechnie
authors.forename: Jessica
authors.initials: J
authors.lastname: Neisen
authors.forename: Nuala
authors.initials: N
authors.lastname: McCabe
authors.forename: Richard D
authors.initials: RD
authors.lastname: Kennedy
authors.forename: Manuel
authors.initials: M
authors.lastname: Salto-Tellez
authors.forename: Chris
authors.initials: C
authors.lastname: Albanese
authors.forename: David J J
authors.initials: DJ
authors.lastname: Waugh
mesh_terms: D000818:Animals; D017209:Apoptosis; D019898:Autocrine Communication; D002277:Carcinoma / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D051059:PTEN Phosphohydrolase / Q000172:deficiency* / Q000235:genetics; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D034622:RNA Interference; D023062:Receptors, Interleukin-8A / Q000378:metabolism; D023063:Receptors, Interleukin-8B / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation
chemical_list: C508606:CXCL8 protein, human; D018836:Inflammation Mediators; D016209:Interleukin-8; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B; D014157:Transcription Factors; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; C487757:Pten protein, mouse