J Pathol Transl Med.  2016 Sep;50(5):369-376. 10.4132/jptm.2016.06.06.

Long Non-coding RNA HOTAIR Expression in Diffuse Large B-Cell Lymphoma: In Relation to Polycomb Repressive Complex Pathway Proteins and H3K27 Trimethylation

• Oh EJ
• Kim SH
• Yang WI
• Ko YH
• Yoon SO

• KMID: 2353599
• DOI: http://doi.org/10.4132/jptm.2016.06.06

Abstract

BACKGROUND
A long non-coding RNA hox transcript antisense intergenic RNA (HOTAIR) is involved in epigenetic regulation through chromatin remodeling by recruiting polycomb repressive complex 2 (PRC2) proteins (EZH2, SUZ12, and EED) that induce histone H3 trimethylation at lysine 27 (H3K27me3). Deregulation of c-MYC and interaction between c-MYC and EZH2 are well known in lymphomagenesis; however, little is known about the expression status of HOTAIR in diffuse large B-cell lymphomas (DLBCLs).
METHODS
The expression status of PRC2 (EZH2, SUZ12, and EED), H3K27me3, c-MYC, and BCL2 was analyzed using immunohistochemistry (n = 231), and HOTAIR was investigated by a quantification real-time polymerase chain reaction method (n = 164) in DLBCLs.
RESULTS
The present study confirmed the positive correlation among PRC2 proteins, H3K27me3, and c-MYC in DLBCLs. Expression level of HOTAIR was also positively correlated to EZH2 (p < .05, respectively). Between c-MYC and HOTAIR, and between c- MYC/BCL2 co-expression and HOTAIR, however, negative correlation was observed in DLBCLs (p < .05, respectively). High level of H3K27me3 was determined as an independent prognostic marker in poor overall survival (hazard ratio, 2.0; p = .023) of DLBCL patients. High expression of HOTAIR, however, was associated with favorable overall survival (p = .004) in the univariate analysis, but the impact was not significant in the multivariate analysis. The favorable outcome of DLBCL with HOTAIR high expression levels may be related to the negative correlation with c- MYC expression or c-MYC/BCL2 co-expression.
CONCLUSIONS
HOTAIR expression could be one of possible mechanisms for inducing H3K27me3 via EZH2-related PRC2 activation, and induced H3K27me3 may be strongly related to aggressive DLBCLs which show poor patient outcome.

Keyword

Lymphoma, large B-cell, diffuse; HOTAIR; hox transcript antisense intergenic RNA; Polycomb repressive complex2; Histone H3trimethylation at lysine 27

MeSH Terms

B-Lymphocytes*
Chromatin Assembly and Disassembly
Epigenomics
Histones
Humans
Immunohistochemistry
Lymphoma, B-Cell*
Lymphoma, Large B-Cell, Diffuse
Lysine
Methods
Multivariate Analysis
Polycomb Repressive Complex 2
Real-Time Polymerase Chain Reaction
RNA
RNA, Long Noncoding*
Histones
Lysine
Polycomb Repressive Complex 2
RNA
RNA, Long Noncoding

Figure

• 

  Fig. 1. A case of DLBCL with HOTAIRhigh (A–F) shows the various expression pattern of c-MYC (A), EZH2 (B), SUZ12 (C), EED (D), global H3K27me3 (E), and BCL2 (F). In a DLBCL case of HOTAIRhigh (A–F), many PRC2 protein (EZH2, SUZ12, and EED)–positive tumor cells show no expression of c-MYC and no mark of H3K27me3. BCL2 was negative in this case. DLBCL, diffuse large B-cell lymphoma; HOTAIR, hox transcript antisense intergenic RNA; EZH2, enhancer of zeste homolog 2; SUZ12, suppressor of zeste 12 homolog; EED, embryonic ectoderm development; PRC2, polycomb repressive complex 2.

• 

  Fig. 2. (A) The DLBCL cases frequently show high expression of PRC2 proteins (EZH2, SUZ12, and EED), high expression of all PRC2 proteins (EZH2high/SUZ12high/EEDhigh), and high H3K27me3 level. (B) When compared to cases without high H3K27me3 expression (low H3K27me3), those with high H3K27me3 expression more frequently show high expression of EZH2, SUZ12, EED, and all PRC2 (EZH2high/SUZ12high/EEDhigh). (C) When compared to cases without high c-MYC expression (low c-MYC), those with high c-MYC expression more frequently show high expression of EZH2, SUZ12, EED, all PRC2 (EZH2high/SUZ12high/EEDhigh), H3K27me3, and BCL2. (D) The expression level of HOTAIR is significantly higher in cases with high EZH2 expression than those without high EZH2 expression (low EZH2). DLBCL, diffuse large B-cell lymphoma; HOTAIR, hox transcript antisense intergenic RNA; EZH2, enhancer of zeste homolog 2; SUZ12, suppressor of zeste 12 homolog; EED, embryonic ectoderm development; PRC2, polycomb repressive complex 2. *p < .05, **p < .001.

• 

  Fig. 3. Overall survival based on SUZ12 (A), H3K27me3 (B), and HOTAIR expression (C). High expression of SUZ12 (SUZ12high) and H3K27me3 (H3K27me3high) is related to inferior overall survival, while high expression of HOTAIR (HOTAIRhigh) is correlated with longer overall survival than low levels of HOTAIR expression (HOTAIRlow). SUZ12, suppressor of zeste 12 homolog; HOTAIR, hox transcript antisense intergenic RNA.

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