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Transcription factors E2A, FOXO1 and FOXP1 regulate recombination activating gene expression in cancer cells.

Chen Z, Xiao Y, Zhang J, Li J, Liu Y, Zhao Y, Ma C, Luo J, Qiu Y, Huang G, Korteweg C, Gu J - PLoS ONE (2011)

Bottom Line: It has long been accepted that immunoglobulins (Igs) were produced by B lymphoid cells only.Chromatin immunoprecipitation experiments showed acetylation of RAG enhancer (Erag) and E2A, FOXO1 or FOXP1 were bound to Erag in vivo.These results indicate that in these cancer cells the transcription factors E2A, FOXO1 and FOXP1 regulate RAG expression, which initiates Ig gene rearrangement much in the way similar to B lymphocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Shantou University Medical College, Shantou, China.

ABSTRACT
It has long been accepted that immunoglobulins (Igs) were produced by B lymphoid cells only. Recently Igs have been found to be expressed in various human cancer cells and promote tumor growth. Recombination activating gene 1 (RAG1) and RAG2, which are essential enzymes for initiating variable-diversity-joining segment recombination, have also been found to be expressed in cancer cells. However, the mechanism of RAG activation in these cancer cells has not been elucidated. Here, we investigated the regulatory mechanism of RAG expression in four human cancer cell lines by analyzing transcription factors that induce RAG activation in B cells. By RT-PCR, Western blot and immunofluorescence, we found that transcription factors E2A, FOXO1 and FOXP1 were expressed and localized to the nuclei of these cancer cells. Over-expression of E2A, FOXO1 or Foxp1 increased RAG expression, while RNA interference of E2A, FOXO1 or FOXP1 decreased RAG expression in the cancer cells. Chromatin immunoprecipitation experiments showed acetylation of RAG enhancer (Erag) and E2A, FOXO1 or FOXP1 were bound to Erag in vivo. These results indicate that in these cancer cells the transcription factors E2A, FOXO1 and FOXP1 regulate RAG expression, which initiates Ig gene rearrangement much in the way similar to B lymphocytes.

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ChIP results showed histone H3 acetylation and E2A, FOXO1, FOXP1 binding of Erag in MCF-7.A, cross-linked chromatin isolated from MCF-7 cells was immunoprecipitated either with isotype control IgG or anti-acetyl-histone H3 antibody. The associated chromosomal DNA fragments were amplified with primers for Erag region 1 and 3. B, the antibody for the immunoprecipitation was anti-E2A, FOXO1 or FOXP1. Experiments were repeated three times with similar results. Similar results were obtained for A549 cell line (data not shown).
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pone-0020475-g006: ChIP results showed histone H3 acetylation and E2A, FOXO1, FOXP1 binding of Erag in MCF-7.A, cross-linked chromatin isolated from MCF-7 cells was immunoprecipitated either with isotype control IgG or anti-acetyl-histone H3 antibody. The associated chromosomal DNA fragments were amplified with primers for Erag region 1 and 3. B, the antibody for the immunoprecipitation was anti-E2A, FOXO1 or FOXP1. Experiments were repeated three times with similar results. Similar results were obtained for A549 cell line (data not shown).

Mentions: In murine B cells transcription factors E2A, Foxo1 and Foxp1 regulate RAG expression through binding to Erag, the enhancer regulating RAG gene expression. In order to investigate whether these transcription factors behave similarly in cancer cells, ChIP was performed on A549 and MCF-7 cells. The Erag region 1 contains three binding sites for E2A and one binding site for FOXO1 or FOXP1, whereas the Erag region 3 contains no binding site for E2A and one binding site for FOXO1 or FOXP1 [25]. ChIP results showed that histone H3 of both Erag region 1 and 3 was acetylated, indicating that Erag was in an open or activated state. In addition, transcription factors E2A, FOXO1 and FOXP1 were demonstrated to be bound to Erag region 1 but not to region 3 (Figure 6). For both cell lines similar results were obtained.


Transcription factors E2A, FOXO1 and FOXP1 regulate recombination activating gene expression in cancer cells.

Chen Z, Xiao Y, Zhang J, Li J, Liu Y, Zhao Y, Ma C, Luo J, Qiu Y, Huang G, Korteweg C, Gu J - PLoS ONE (2011)

ChIP results showed histone H3 acetylation and E2A, FOXO1, FOXP1 binding of Erag in MCF-7.A, cross-linked chromatin isolated from MCF-7 cells was immunoprecipitated either with isotype control IgG or anti-acetyl-histone H3 antibody. The associated chromosomal DNA fragments were amplified with primers for Erag region 1 and 3. B, the antibody for the immunoprecipitation was anti-E2A, FOXO1 or FOXP1. Experiments were repeated three times with similar results. Similar results were obtained for A549 cell line (data not shown).
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105062&req=5

pone-0020475-g006: ChIP results showed histone H3 acetylation and E2A, FOXO1, FOXP1 binding of Erag in MCF-7.A, cross-linked chromatin isolated from MCF-7 cells was immunoprecipitated either with isotype control IgG or anti-acetyl-histone H3 antibody. The associated chromosomal DNA fragments were amplified with primers for Erag region 1 and 3. B, the antibody for the immunoprecipitation was anti-E2A, FOXO1 or FOXP1. Experiments were repeated three times with similar results. Similar results were obtained for A549 cell line (data not shown).
Mentions: In murine B cells transcription factors E2A, Foxo1 and Foxp1 regulate RAG expression through binding to Erag, the enhancer regulating RAG gene expression. In order to investigate whether these transcription factors behave similarly in cancer cells, ChIP was performed on A549 and MCF-7 cells. The Erag region 1 contains three binding sites for E2A and one binding site for FOXO1 or FOXP1, whereas the Erag region 3 contains no binding site for E2A and one binding site for FOXO1 or FOXP1 [25]. ChIP results showed that histone H3 of both Erag region 1 and 3 was acetylated, indicating that Erag was in an open or activated state. In addition, transcription factors E2A, FOXO1 and FOXP1 were demonstrated to be bound to Erag region 1 but not to region 3 (Figure 6). For both cell lines similar results were obtained.

Bottom Line: It has long been accepted that immunoglobulins (Igs) were produced by B lymphoid cells only.Chromatin immunoprecipitation experiments showed acetylation of RAG enhancer (Erag) and E2A, FOXO1 or FOXP1 were bound to Erag in vivo.These results indicate that in these cancer cells the transcription factors E2A, FOXO1 and FOXP1 regulate RAG expression, which initiates Ig gene rearrangement much in the way similar to B lymphocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Shantou University Medical College, Shantou, China.

ABSTRACT
It has long been accepted that immunoglobulins (Igs) were produced by B lymphoid cells only. Recently Igs have been found to be expressed in various human cancer cells and promote tumor growth. Recombination activating gene 1 (RAG1) and RAG2, which are essential enzymes for initiating variable-diversity-joining segment recombination, have also been found to be expressed in cancer cells. However, the mechanism of RAG activation in these cancer cells has not been elucidated. Here, we investigated the regulatory mechanism of RAG expression in four human cancer cell lines by analyzing transcription factors that induce RAG activation in B cells. By RT-PCR, Western blot and immunofluorescence, we found that transcription factors E2A, FOXO1 and FOXP1 were expressed and localized to the nuclei of these cancer cells. Over-expression of E2A, FOXO1 or Foxp1 increased RAG expression, while RNA interference of E2A, FOXO1 or FOXP1 decreased RAG expression in the cancer cells. Chromatin immunoprecipitation experiments showed acetylation of RAG enhancer (Erag) and E2A, FOXO1 or FOXP1 were bound to Erag in vivo. These results indicate that in these cancer cells the transcription factors E2A, FOXO1 and FOXP1 regulate RAG expression, which initiates Ig gene rearrangement much in the way similar to B lymphocytes.

Show MeSH
Related in: MedlinePlus