title: DNA methylation and histone modifications regulate SOX11 expression in lymphoid and solid cancer cells.
abstract: BACKGROUND
  The neural transcription factor SOX11 is present at specific stages during embryo development with a very restricted expression in adult tissue, indicating precise regulation of transcription. SOX11 is strongly up-regulated in some malignancies and have a functional role in tumorgenesis. With the aim to explore differences in epigenetic regulation of SOX11 expression in normal versus neoplastic cells, we investigated methylation and histone modifications related to the SOX11 promoter and the possibility to induce re-expression using histone deacetylase (HDAC) or EZH2 inhibitors.
  
  
  METHODS
  The epigenetic regulation of SOX11 was investigated in distinct non-malignant cell populations (n = 7) and neoplastic cell-lines (n = 42) of different cellular origins. DNA methylation was assessed using bisulfite sequencing, methylation-specific melting curve analysis, MethyLight and pyrosequencing. The presence of H3K27me3 was assessed using ChIP-qPCR. The HDAC inhibitors Vorinostat and trichostatin A were used to induce SOX11 in cell lines with no endogenous expression.
  
  
  RESULTS
  The SOX11 promoter shows a low degree of methylation and strong enrichment of H3K27me3 in non-malignant differentiated cells, independent of cellular origin. Cancers of the B-cell lineage are strongly marked by de novo methylation at the SOX11 promoter in SOX11 non-expressing cells, while solid cancer entities display a more varying degree of SOX11 promoter methylation. The silencing mark H3K27me3 was generally present at the SOX11 promoter in non-expressing cells, and an increased enrichment was observed in cancer cells with a low degree of SOX11 methylation compared to cells with dense methylation. Finally, we demonstrate that the HDAC inhibitors (vorinostat and trichostatin A) induce SOX11 expression in cancer cells with low levels of SOX11 methylation.
  
  
  CONCLUSIONS
  We show that SOX11 is strongly marked by repressive histone marks in non-malignant cells. In contrast, SOX11 regulation in neoplastic tissues is more complex involving both DNA methylation and histone modifications. The possibility to re-express SOX11 in non-methylated tissue is of clinical relevance, and was successfully achieved in cell lines with low levels of SOX11 methylation. In breast cancer patients, methylation of the SOX11 promoter was shown to correlate with estrogen receptor status, suggesting that SOX11 may be functionally re-expressed during treatment with HDAC inhibitors in specific patient subgroups.
authors.affiliation: Department of Immunotechnology, CREATE Health, Lund University, Lund, Sweden. lena.nordstrom@immun.lth.se.
authors.forename: Lena
authors.initials: L
authors.lastname: Nordström
authors.affiliation: Danish Cancer Society Research Center, Copenhagen, Denmark. elinandersson74@gmail.com.
authors.forename: Elin
authors.initials: E
authors.lastname: Andersson
authors.affiliation: Department of Immunotechnology, CREATE Health, Lund University, Lund, Sweden. venera.kuci@immun.lth.se.
authors.forename: Venera
authors.initials: V
authors.lastname: Kuci
authors.affiliation: Department of Immunotechnology, CREATE Health, Lund University, Lund, Sweden. elin.gustavsson@roche.com.
authors.forename: Elin
authors.initials: E
authors.lastname: Gustavsson
authors.affiliation: Department of Oncology and Pathology, Clinical Sciences, Lund University, Skåne University Hospital, Lund, Sweden. karolina.holm@med.lu.se.
authors.forename: Karolina
authors.initials: K
authors.lastname: Holm
authors.affiliation: Department of Oncology and Pathology, Clinical Sciences, Lund University, Skåne University Hospital, Lund, Sweden. markus.ringner@med.lu.se.
authors.forename: Markus
authors.initials: M
authors.lastname: Ringnér
authors.affiliation: Danish Cancer Society Research Center, Copenhagen, Denmark. PerG@cancer.dk.
authors.forename: Per
authors.initials: P
authors.lastname: Guldberg
authors.affiliation: Department of Immunotechnology, CREATE Health, Lund University, Lund, Sweden. sara.ek@immun.lth.se.
authors.forename: Sara
authors.initials: S
authors.lastname: Ek
mesh_terms: D045744:Cell Line, Tumor; D019175:DNA Methylation / Q000187:drug effects; D044127:Epigenesis, Genetic / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D042421:Histone Code / Q000187:drug effects; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D009369:Neoplasms / Q000235:genetics* / Q000378:metabolism; D014066:Palatine Tonsil / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects; D055751:SOXC Transcription Factors / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D000077337:Vorinostat
chemical_list: D006877:Hydroxamic Acids; C097473:SOX11 protein, human; D055751:SOXC Transcription Factors; C012589:trichostatin A; D000077337:Vorinostat