Limits...
Selective increase in subtelomeric DNA methylation: an epigenetic biomarker for malignant glioma.

Choudhury SR, Cui Y, Milton JR, Li J, Irudayaraj J - Clin Epigenetics (2015)

Bottom Line: Selective changes in the subtelomeric methylation level, however, did not show any significant correlation to the global TL.AZA treatment caused significant changes in the subtelomeric methylation pattern but did not alter the TL, which supports our hypothesis.Alterations in subtelomeric methylation, however, have no effects on the TL.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Engineering, Center for Cancer Research, Purdue University, West Lafayette, IN 47906 USA.

ABSTRACT

Background: Subtelomeric regions dynamically change their epigenetic pattern during development and progression of several malignancies and degenerative disorders. However, DNA methylation of human subtelomeres and their correlation to telomere length (TL) remain undetermined in glioma.

Results: Herein, we report on the selective changes in subtelomeric DNA methylation at the end of five chromosomes (Chr.) (7q, 8q. 18p, 21q, and XpYp) and ascertain their correlation with TL in patients with glioma. Subtelomeric methylation level was invariably higher in glioma patients compared to the control group, irrespective of their age and tumor grade. In particular, a significant increase in methylation was observed at the subtelomeric CpG sites of Chr. 8q, 21q, and XpYp in tissues, obtained from the brain tumor of glioma patients. In contrast, no significant change in methylation was observed at the subtelomere of Chr. 7q and 18p. Selective changes in the subtelomeric methylation level, however, did not show any significant correlation to the global TL. This observed phenomenon was validated in vitro by inducing demethylation in a glioblastoma cell line (SF-767) using 5-azacytidine (AZA) treatment. AZA treatment caused significant changes in the subtelomeric methylation pattern but did not alter the TL, which supports our hypothesis.

Conclusions: DNA methylation level dramatically increased at the subtelomere of Chr.8q, 21q, and XpYp in malignant glioma, which could be used as an early epigenetic diagnostic biomarker of the disease. Alterations in subtelomeric methylation, however, have no effects on the TL.

No MeSH data available.


Related in: MedlinePlus

a Induced demethylation was recognized with the increased band intensity of the amplicons against the unmethylation (U)-specific primers in AZA-treated SF-767 cell line. b The adjacent bar chart, extracted from the gel image expresses the change in demethylation ratio between the non-treated and AZA-treated replica. The demethylation ratio at each of the subtelomeres was increased in comparison to the untreated replica. Nonetheless, we did not observe any significant alteration in TL after treatment with AZA (c).
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4597615&req=5

Fig6: a Induced demethylation was recognized with the increased band intensity of the amplicons against the unmethylation (U)-specific primers in AZA-treated SF-767 cell line. b The adjacent bar chart, extracted from the gel image expresses the change in demethylation ratio between the non-treated and AZA-treated replica. The demethylation ratio at each of the subtelomeres was increased in comparison to the untreated replica. Nonetheless, we did not observe any significant alteration in TL after treatment with AZA (c).

Mentions: To cross validate the lack of correlation between TL and subtelomeric methylation in glioma, a global demethylation was induced in SF-767 cells with AZA. Subtelomeric methylation level at each of the chromosomes was then determined alongside the global TL, before and after the drug treatment. The band intensity of the demethylation specific amplicons from the subtelomeric regions of each chromosome was found to increase upon drug treatment (Fig.6a). We have also determined the change in demethylation ratio among the AZA-treated genomic replicates over the negative control (Fig.6b). The highest increment in the demethylation ratio was observed for chromosome 8q, followed by XpYp, 7q, 21q, and 18p. However, we have noticed no significant change in the TL (T/S) between the untreated (2.346 ± 0.034) and AZA-treated (2.358 ± 0.049) cells (Fig. 6c). These lines of experiments served as the in vitro validation of the observed phenomenon in the clinical isolates and also support the claim that there may not be any significant correlation between subtelomeric DNA methylation level and global change in TL in glioma.Fig. 6


Selective increase in subtelomeric DNA methylation: an epigenetic biomarker for malignant glioma.

Choudhury SR, Cui Y, Milton JR, Li J, Irudayaraj J - Clin Epigenetics (2015)

a Induced demethylation was recognized with the increased band intensity of the amplicons against the unmethylation (U)-specific primers in AZA-treated SF-767 cell line. b The adjacent bar chart, extracted from the gel image expresses the change in demethylation ratio between the non-treated and AZA-treated replica. The demethylation ratio at each of the subtelomeres was increased in comparison to the untreated replica. Nonetheless, we did not observe any significant alteration in TL after treatment with AZA (c).
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4597615&req=5

Fig6: a Induced demethylation was recognized with the increased band intensity of the amplicons against the unmethylation (U)-specific primers in AZA-treated SF-767 cell line. b The adjacent bar chart, extracted from the gel image expresses the change in demethylation ratio between the non-treated and AZA-treated replica. The demethylation ratio at each of the subtelomeres was increased in comparison to the untreated replica. Nonetheless, we did not observe any significant alteration in TL after treatment with AZA (c).
Mentions: To cross validate the lack of correlation between TL and subtelomeric methylation in glioma, a global demethylation was induced in SF-767 cells with AZA. Subtelomeric methylation level at each of the chromosomes was then determined alongside the global TL, before and after the drug treatment. The band intensity of the demethylation specific amplicons from the subtelomeric regions of each chromosome was found to increase upon drug treatment (Fig.6a). We have also determined the change in demethylation ratio among the AZA-treated genomic replicates over the negative control (Fig.6b). The highest increment in the demethylation ratio was observed for chromosome 8q, followed by XpYp, 7q, 21q, and 18p. However, we have noticed no significant change in the TL (T/S) between the untreated (2.346 ± 0.034) and AZA-treated (2.358 ± 0.049) cells (Fig. 6c). These lines of experiments served as the in vitro validation of the observed phenomenon in the clinical isolates and also support the claim that there may not be any significant correlation between subtelomeric DNA methylation level and global change in TL in glioma.Fig. 6

Bottom Line: Selective changes in the subtelomeric methylation level, however, did not show any significant correlation to the global TL.AZA treatment caused significant changes in the subtelomeric methylation pattern but did not alter the TL, which supports our hypothesis.Alterations in subtelomeric methylation, however, have no effects on the TL.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Engineering, Center for Cancer Research, Purdue University, West Lafayette, IN 47906 USA.

ABSTRACT

Background: Subtelomeric regions dynamically change their epigenetic pattern during development and progression of several malignancies and degenerative disorders. However, DNA methylation of human subtelomeres and their correlation to telomere length (TL) remain undetermined in glioma.

Results: Herein, we report on the selective changes in subtelomeric DNA methylation at the end of five chromosomes (Chr.) (7q, 8q. 18p, 21q, and XpYp) and ascertain their correlation with TL in patients with glioma. Subtelomeric methylation level was invariably higher in glioma patients compared to the control group, irrespective of their age and tumor grade. In particular, a significant increase in methylation was observed at the subtelomeric CpG sites of Chr. 8q, 21q, and XpYp in tissues, obtained from the brain tumor of glioma patients. In contrast, no significant change in methylation was observed at the subtelomere of Chr. 7q and 18p. Selective changes in the subtelomeric methylation level, however, did not show any significant correlation to the global TL. This observed phenomenon was validated in vitro by inducing demethylation in a glioblastoma cell line (SF-767) using 5-azacytidine (AZA) treatment. AZA treatment caused significant changes in the subtelomeric methylation pattern but did not alter the TL, which supports our hypothesis.

Conclusions: DNA methylation level dramatically increased at the subtelomere of Chr.8q, 21q, and XpYp in malignant glioma, which could be used as an early epigenetic diagnostic biomarker of the disease. Alterations in subtelomeric methylation, however, have no effects on the TL.

No MeSH data available.


Related in: MedlinePlus