title: Recruitment of regulatory T cells is correlated with hypoxia-induced CXCR4 expression, and is associated with poor prognosis in basal-like breast cancers.
abstract: BACKGROUND
  Basal-like breast cancers behave more aggressively despite the presence of a dense lymphoid infiltrate. We hypothesised that immune suppression in this subtype may be due to T regulatory cells (Treg) recruitment driven by hypoxia-induced up-regulation of CXCR4 in Treg.
  
  
  METHODS
  Immunoperoxidase staining for FOXP3 and CXCL12 was performed on tissue microarrays from 491 breast cancers. The hypoxia-associated marker carbonic anhydrase IX (CA9) and double FOXP3/CXCR4 staining were performed on sections from a subset of these cancers including 10 basal-like and 11 luminal cancers matched for tumour grade.
  
  
  RESULTS
  High Treg infiltration correlated with tumour CXCL12 positivity (OR 1.89, 95% CI 1.22 to 2.94, P = 0.004) and basal phenotype (OR 3.14, 95% CI 1.08 to 9.17, P = 0.004) in univariate and multivariate analyses. CXCL12 positivity correlated with improved survival (P = 0.005), whereas high Treg correlated with shorter survival for all breast cancers (P = 0.001), luminal cancers (P < 0.001) and basal-like cancers (P = 0.040) that were confirmed in a multivariate analysis (OR 1.61, 95% CI 1.02 to 2.53, P = 0.042). In patients treated with hormone therapy, high Treg were associated with a shorter survival in a multivariate analysis (OR 1.78, 95% CI 1.01 to 3.15, P = 0.040). There was a tendency for luminal cancers to show CXCL12 expression (102/138, 74%) compared to basal-like cancers (16/27, 59%), which verged on statistical significance (P = 0.050). Up-regulation of CXCR4 in Treg correlated with the basal-like phenotype (P = 0.029) and tumour hypoxia, as indicated by CA9 expression (P = 0.049).
  
  
  CONCLUSIONS
  Our data show that in the setting of hypoxia and CXCR4 up-regulation in Treg, CXCL12 expression may have the negative consequence of enhancing Treg recruitment and suppressing the anti-tumour immune response.
authors.affiliation: Department of Pathology, Peter MacCallum Cancer Centre, St Andrews Place, East Melbourne, Melbourne, VIC 3002, Australia. max.yan@sesiahs.health.nsw.gov.au
authors.forename: Max
authors.initials: M
authors.lastname: Yan
authors.forename: Nicholas
authors.initials: N
authors.lastname: Jene
authors.forename: David
authors.initials: D
authors.lastname: Byrne
authors.forename: Ewan K A
authors.initials: EK
authors.lastname: Millar
authors.forename: Sandra A
authors.initials: SA
authors.lastname: O'Toole
authors.forename: Catriona M
authors.initials: CM
authors.lastname: McNeil
authors.forename: Gaynor J
authors.initials: GJ
authors.lastname: Bates
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Harris
authors.forename: Alison H
authors.initials: AH
authors.lastname: Banham
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sutherland
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Fox
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000096:biosynthesis; D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000096:biosynthesis; D015687:Cell Hypoxia; D054377:Chemokine CXCL12 / Q000096:biosynthesis; D005260:Female; D051858:Forkhead Transcription Factors / Q000096:biosynthesis; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011379:Prognosis; D019718:Receptors, CXCR4 / Q000096:biosynthesis*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D019718:Receptors, CXCR4; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases