TY - JOUR
T1 - Escape mechanisms from antibody therapy to lymphoma cells
T2 - Downregulation of CD20 mRNA by recruitment of the HDAC complex and not by DNA methylation
AU - Sugimoto, Takumi
AU - Tomita, Akihiro
AU - Hiraga, Junji
AU - Shimada, Kazuyuki
AU - Kiyoi, Hitoshi
AU - Kinoshita, Tomohiro
AU - Naoe, Tomoki
N1 - Funding Information:
This work is supported in part by a Grant-in-Aid for Cancer Research ( 21-6-3 ) from the Ministry of Health, Labor and Welfare , a Grant-in-Aid from the National Institute of Biomedical Innovation , and a Grant-in-Aid in Scientific Research ( 20591116 ) from the Ministry of Education, Culture, Sports, Science and Technology, Japan . We thank Dr. Shinsuke Iida for providing critical information about IRF4. We also thank Akihide Atsumi, Tomoka Wakamatsu, Yukie Konishi, Mari Otsuka, Eriko Ushida, and Chieko Kataoka for valuable laboratory assistance.
PY - 2009/12/4
Y1 - 2009/12/4
N2 - Although rituximab is a critical monoclonal antibody therapy for CD20-positive B-cell lymphomas, rituximab resistance showing a CD20-negative phenotypic change has been a considerable clinical problem. Here we demonstrate that CD20 mRNA and protein expression is repressed by recruitment of a histone deacetylase protein complex to the MS4A1 (CD20) gene promoter in CD20-negative transformed cells after treatment with rituximab. CD20 mRNA and protein expression were stimulated by decitabine (5-Aza-dC) in CD20-negative transformed cells, and was enhanced by trichostation A (TSA). Immunoblotting indicated that DNMT1 expression was first downregulated 1 day after treatment with 5-Aza-dC, but IRF4 and Pu.1, the transcriptional regulators of MS4A1, were still expressed with or without 5-Aza-dC. Interestingly, CpG methylation of the MS4A1 promoter was not observed in CD20-negative transformed cells without 5-Aza-dC. A chromatin immunoprecipitation (ChIP) assay indicated that the Sin3A-HDAC1 co-repressor complex was recruited to the promoter and dissociated from the promoter with 5-Aza-dC and TSA, resulting in histone acetylation. Under these conditions, IRF4 and Pu.1 were continually recruited to the promoter with or without 5-Aza-dC and TSA. These results suggest that recruitment of the Sin3A-HDAC1 complex is related to downregulation of CD20 expression in CD20-negative B-cells after treatment with rituximab.
AB - Although rituximab is a critical monoclonal antibody therapy for CD20-positive B-cell lymphomas, rituximab resistance showing a CD20-negative phenotypic change has been a considerable clinical problem. Here we demonstrate that CD20 mRNA and protein expression is repressed by recruitment of a histone deacetylase protein complex to the MS4A1 (CD20) gene promoter in CD20-negative transformed cells after treatment with rituximab. CD20 mRNA and protein expression were stimulated by decitabine (5-Aza-dC) in CD20-negative transformed cells, and was enhanced by trichostation A (TSA). Immunoblotting indicated that DNMT1 expression was first downregulated 1 day after treatment with 5-Aza-dC, but IRF4 and Pu.1, the transcriptional regulators of MS4A1, were still expressed with or without 5-Aza-dC. Interestingly, CpG methylation of the MS4A1 promoter was not observed in CD20-negative transformed cells without 5-Aza-dC. A chromatin immunoprecipitation (ChIP) assay indicated that the Sin3A-HDAC1 co-repressor complex was recruited to the promoter and dissociated from the promoter with 5-Aza-dC and TSA, resulting in histone acetylation. Under these conditions, IRF4 and Pu.1 were continually recruited to the promoter with or without 5-Aza-dC and TSA. These results suggest that recruitment of the Sin3A-HDAC1 complex is related to downregulation of CD20 expression in CD20-negative B-cells after treatment with rituximab.
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U2 - 10.1016/j.bbrc.2009.09.059
DO - 10.1016/j.bbrc.2009.09.059
M3 - Article
C2 - 19769942
AN - SCOPUS:70349958004
SN - 0006-291X
VL - 390
SP - 48
EP - 53
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -