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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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Immunofluorescence showing NF-κB p65, E2A, FOXO1 and FOXP1 localization in the MCF-7 cell line.A, normal mouse IgG was used instead of the primary antibody. B, the primary antibody was mouse anti-E2A. C, the primary antibody was mouse anti-NF-κB p65. A to C, the secondary antibody was goat anti-mouse IgG-FITC. D, normal rabbit IgG was used instead of the primary antibody. E, the primary antibody was rabbit anti-FOXO1. F, the primary antibody was rabbit anti-FOXP1. D to F, the secondary antibody was goat anti-rabbit IgG-TRITC. Similar results were obtained for the A549, PC3 and MDA-MB-231 cell lines (data not shown).
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pone-0020475-g003: Immunofluorescence showing NF-κB p65, E2A, FOXO1 and FOXP1 localization in the MCF-7 cell line.A, normal mouse IgG was used instead of the primary antibody. B, the primary antibody was mouse anti-E2A. C, the primary antibody was mouse anti-NF-κB p65. A to C, the secondary antibody was goat anti-mouse IgG-FITC. D, normal rabbit IgG was used instead of the primary antibody. E, the primary antibody was rabbit anti-FOXO1. F, the primary antibody was rabbit anti-FOXP1. D to F, the secondary antibody was goat anti-rabbit IgG-TRITC. Similar results were obtained for the A549, PC3 and MDA-MB-231 cell lines (data not shown).

Mentions: To study the localization of E2A, FOXO1, FOXP1 and NF-κB in cancer cells, IF was performed using the corresponding antibodies on the four cancer cell lines. The results showed that E2A and FOXP1 were predominantly localized to the nucleus, whereas NF-κB was exclusively localized to the cytoplasm of the cancer cells (Figure 3). FOXO1 was found to translocate between the nucleus and cytoplasm, with the location depending on the culture and growth conditions. When the cells were confluent, FOXO1 was mainly located in the nucleus, while it was mainly present in the cytoplasm when the cells were sparse. Since transcription factors need to be localized in the nucleus in order to regulate gene expression, we just focused on E2A, FOXO1 and FOXP1 in the second part of our study.


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)

Immunofluorescence showing NF-κB p65, E2A, FOXO1 and FOXP1 localization in the MCF-7 cell line.A, normal mouse IgG was used instead of the primary antibody. B, the primary antibody was mouse anti-E2A. C, the primary antibody was mouse anti-NF-κB p65. A to C, the secondary antibody was goat anti-mouse IgG-FITC. D, normal rabbit IgG was used instead of the primary antibody. E, the primary antibody was rabbit anti-FOXO1. F, the primary antibody was rabbit anti-FOXP1. D to F, the secondary antibody was goat anti-rabbit IgG-TRITC. Similar results were obtained for the A549, PC3 and MDA-MB-231 cell lines (data not shown).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0020475-g003: Immunofluorescence showing NF-κB p65, E2A, FOXO1 and FOXP1 localization in the MCF-7 cell line.A, normal mouse IgG was used instead of the primary antibody. B, the primary antibody was mouse anti-E2A. C, the primary antibody was mouse anti-NF-κB p65. A to C, the secondary antibody was goat anti-mouse IgG-FITC. D, normal rabbit IgG was used instead of the primary antibody. E, the primary antibody was rabbit anti-FOXO1. F, the primary antibody was rabbit anti-FOXP1. D to F, the secondary antibody was goat anti-rabbit IgG-TRITC. Similar results were obtained for the A549, PC3 and MDA-MB-231 cell lines (data not shown).
Mentions: To study the localization of E2A, FOXO1, FOXP1 and NF-κB in cancer cells, IF was performed using the corresponding antibodies on the four cancer cell lines. The results showed that E2A and FOXP1 were predominantly localized to the nucleus, whereas NF-κB was exclusively localized to the cytoplasm of the cancer cells (Figure 3). FOXO1 was found to translocate between the nucleus and cytoplasm, with the location depending on the culture and growth conditions. When the cells were confluent, FOXO1 was mainly located in the nucleus, while it was mainly present in the cytoplasm when the cells were sparse. Since transcription factors need to be localized in the nucleus in order to regulate gene expression, we just focused on E2A, FOXO1 and FOXP1 in the second part of our study.

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