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Expression of the CTCF-paralogous cancer-testis gene, brother of the regulator of imprinted sites (BORIS), is regulated by three alternative promoters modulated by CpG methylation and by CTCF and p53 transcription factors.

Renaud S, Pugacheva EM, Delgado MD, Braunschweig R, Abdullaev Z, Loukinov D, Benhattar J, Lobanenkov V - Nucleic Acids Res. (2007)

Bottom Line: We found that DNA methylation and functional p53 contributes to the negative regulation of each promoter.Moreover, reduction of CTCF in normally BORIS-negative human fibroblasts resulted in derepression of BORIS promoters.These results provide a mechanistic basis for understanding cancer-related associations between haploinsufficiency of CTCF and BORIS derepression, and between the lack of functional p53 and aberrant activation of BORIS.

View Article: PubMed Central - PubMed

Affiliation: Section of Molecular Pathology, Laboratory of Immunopathology, NIAID, NIH, Rockville, MD 20815, USA.

ABSTRACT
BORIS, like other members of the 'cancer/testis antigen' family, is normally expressed in testicular germ cells and repressed in somatic cells, but is aberrantly activated in cancers. To understand regulatory mechanisms governing human BORIS expression, we characterized its 5'-flanking region. Using 5' RACE, we identified three promoters, designated A, B and C, corresponding to transcription start sites at -1447, -899 and -658 bp upstream of the first ATG. Alternative promoter usage generated at least five alternatively spliced BORIS mRNAs with different half-lives determined by varying 5'-UTRs. In normal testis, BORIS is transcribed from all three promoters, but 84% of the 30 cancer cell lines tested used only promoter(s) A and/or C while the others utilized primarily promoters B and C. The differences in promoter usage between normal and cancer cells suggested that they were subject to differential regulation. We found that DNA methylation and functional p53 contributes to the negative regulation of each promoter. Moreover, reduction of CTCF in normally BORIS-negative human fibroblasts resulted in derepression of BORIS promoters. These results provide a mechanistic basis for understanding cancer-related associations between haploinsufficiency of CTCF and BORIS derepression, and between the lack of functional p53 and aberrant activation of BORIS.

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BORIS expression from different alternative promoters (A, B and C) in normal testis and in multiple types of cancer cell lines by real-time PCR. (A) Relative expression of BORIS from the three different promoters in normal testis. (B) Relative expression of BORIS from the three different promoters in 31 different tumor cell lines. Tumor cell lines are divided in four groups according to the main promoter usage. Group B represents 16% of all cell lines tested and the BORIS expression is mainly originated from promoter B. In the three other groups the activity of BORIS comes from either promoter A, either promoter C or from promoters A and C. These three groups represent 84% of all cell lines tested.
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Figure 3: BORIS expression from different alternative promoters (A, B and C) in normal testis and in multiple types of cancer cell lines by real-time PCR. (A) Relative expression of BORIS from the three different promoters in normal testis. (B) Relative expression of BORIS from the three different promoters in 31 different tumor cell lines. Tumor cell lines are divided in four groups according to the main promoter usage. Group B represents 16% of all cell lines tested and the BORIS expression is mainly originated from promoter B. In the three other groups the activity of BORIS comes from either promoter A, either promoter C or from promoters A and C. These three groups represent 84% of all cell lines tested.

Mentions: To gain further insights into the characteristics of promoters A, B and C, we studied their utilization by qPCR in a panel of normal tissues, normal cell lines and cancer cell lines. As expected from previous studies, testis was the only normal tissue to express BORIS (data not shown). The relative percent of expression from each promoter was then calculated. Figure 3A shows that in normal testis, expression comes from all three promoters. The distribution of activity is 47% from promoter A, 12% from promoter B and 41% from promoter C.Figure 3.


Expression of the CTCF-paralogous cancer-testis gene, brother of the regulator of imprinted sites (BORIS), is regulated by three alternative promoters modulated by CpG methylation and by CTCF and p53 transcription factors.

Renaud S, Pugacheva EM, Delgado MD, Braunschweig R, Abdullaev Z, Loukinov D, Benhattar J, Lobanenkov V - Nucleic Acids Res. (2007)

BORIS expression from different alternative promoters (A, B and C) in normal testis and in multiple types of cancer cell lines by real-time PCR. (A) Relative expression of BORIS from the three different promoters in normal testis. (B) Relative expression of BORIS from the three different promoters in 31 different tumor cell lines. Tumor cell lines are divided in four groups according to the main promoter usage. Group B represents 16% of all cell lines tested and the BORIS expression is mainly originated from promoter B. In the three other groups the activity of BORIS comes from either promoter A, either promoter C or from promoters A and C. These three groups represent 84% of all cell lines tested.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2175345&req=5

Figure 3: BORIS expression from different alternative promoters (A, B and C) in normal testis and in multiple types of cancer cell lines by real-time PCR. (A) Relative expression of BORIS from the three different promoters in normal testis. (B) Relative expression of BORIS from the three different promoters in 31 different tumor cell lines. Tumor cell lines are divided in four groups according to the main promoter usage. Group B represents 16% of all cell lines tested and the BORIS expression is mainly originated from promoter B. In the three other groups the activity of BORIS comes from either promoter A, either promoter C or from promoters A and C. These three groups represent 84% of all cell lines tested.
Mentions: To gain further insights into the characteristics of promoters A, B and C, we studied their utilization by qPCR in a panel of normal tissues, normal cell lines and cancer cell lines. As expected from previous studies, testis was the only normal tissue to express BORIS (data not shown). The relative percent of expression from each promoter was then calculated. Figure 3A shows that in normal testis, expression comes from all three promoters. The distribution of activity is 47% from promoter A, 12% from promoter B and 41% from promoter C.Figure 3.

Bottom Line: We found that DNA methylation and functional p53 contributes to the negative regulation of each promoter.Moreover, reduction of CTCF in normally BORIS-negative human fibroblasts resulted in derepression of BORIS promoters.These results provide a mechanistic basis for understanding cancer-related associations between haploinsufficiency of CTCF and BORIS derepression, and between the lack of functional p53 and aberrant activation of BORIS.

View Article: PubMed Central - PubMed

Affiliation: Section of Molecular Pathology, Laboratory of Immunopathology, NIAID, NIH, Rockville, MD 20815, USA.

ABSTRACT
BORIS, like other members of the 'cancer/testis antigen' family, is normally expressed in testicular germ cells and repressed in somatic cells, but is aberrantly activated in cancers. To understand regulatory mechanisms governing human BORIS expression, we characterized its 5'-flanking region. Using 5' RACE, we identified three promoters, designated A, B and C, corresponding to transcription start sites at -1447, -899 and -658 bp upstream of the first ATG. Alternative promoter usage generated at least five alternatively spliced BORIS mRNAs with different half-lives determined by varying 5'-UTRs. In normal testis, BORIS is transcribed from all three promoters, but 84% of the 30 cancer cell lines tested used only promoter(s) A and/or C while the others utilized primarily promoters B and C. The differences in promoter usage between normal and cancer cells suggested that they were subject to differential regulation. We found that DNA methylation and functional p53 contributes to the negative regulation of each promoter. Moreover, reduction of CTCF in normally BORIS-negative human fibroblasts resulted in derepression of BORIS promoters. These results provide a mechanistic basis for understanding cancer-related associations between haploinsufficiency of CTCF and BORIS derepression, and between the lack of functional p53 and aberrant activation of BORIS.

Show MeSH
Related in: MedlinePlus