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Axin gene methylation status correlates with radiosensitivity of lung cancer cells.

Yang LH, Han Y, Li G, Xu HT, Jiang GY, Miao Y, Zhang XP, Zhao HY, Xu ZF, Stoecker M, Wang E, Xu K, Wang EH - BMC Cancer (2013)

Bottom Line: The mechanisms, however, were not clear.Real-time PCR was used to quantify the expression of Axin, and western blot analysis was applied to measure protein levels of Axin, β-catenin, Cyclin D1, MMP-7, DNMTS, MeCP2 and acetylated histones.Hypermethylated Axin gene was detected in 2 of 4 cell lines, and it correlated inversely with Axin expression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China.

ABSTRACT

Background: We previously reported that Axin1 (Axin) is down-regulated in many cases of lung cancer, and X-ray irradiation increased Axin expression and inhibited lung cancer cells. The mechanisms, however, were not clear.

Methods: Four lung cancer cell lines were used to detect the methylation status of Axin with or without X-ray treatment. Real-time PCR was used to quantify the expression of Axin, and western blot analysis was applied to measure protein levels of Axin, β-catenin, Cyclin D1, MMP-7, DNMTS, MeCP2 and acetylated histones. Flow cytometric analysis, colony formation assay, transwell assay and xenograft growth experiment were used to study the biological behavior of the cells with hypermethylated or unmethylated Axin gene after X-ray treatment.

Results: Hypermethylated Axin gene was detected in 2 of 4 cell lines, and it correlated inversely with Axin expression. X-ray treatment significantly up-regulated Axin expression in H446 and H157 cells, which possess intrinsic hypermethylation of the Axin gene (P<0.01), but did not show up-regulation in LTE and H460 cells, which have unmethylated Axin gene. 2Gy X-ray significantly reduced colony formation (from 71% to 10.5%) in H157 cells, while the reduction was lower in LTE cells (from 71% to 20%). After X-ray irradiation, xenograft growth was significantly decreased in H157 cells (from 1.15 g to 0.28 g) in comparison with LTE cells (from 1.06 g to 0.65 g). Significantly decreased cell invasiveness and increased apoptosis were also observed in H157 cells treated with X-ray irradiation (P<0.01). Down-regulation of DNMTs and MeCP2 and up-regulation of acetylated histones could be detected in lung cancer cells.

Conclusions: X-ray-induced inhibition of lung cancer cells may be mediated by enhanced expression of Axin via genomic DNA demethylation and histone acetylation. Lung cancer cells with a different methylation status of the Axin gene showed different radiosensitivity, suggesting that the methylation status of the Axin gene may be one important factor to predict radiosensitivity of the tumor.

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The effect of X-ray irradiation on methylation status of the Axin gene in lung cancer cell lines. There is no obvious change in unmethylated status of the Axin promoter and first intron in the LTE (A) and H460 (D) cell lines after X-ray irradiation, while significant demethylation could be detected in the second intron of H157 cells (B) and the promoter and first intron in H446 cells (C).
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Figure 2: The effect of X-ray irradiation on methylation status of the Axin gene in lung cancer cell lines. There is no obvious change in unmethylated status of the Axin promoter and first intron in the LTE (A) and H460 (D) cell lines after X-ray irradiation, while significant demethylation could be detected in the second intron of H157 cells (B) and the promoter and first intron in H446 cells (C).

Mentions: MSP demonstrated that there was no change of the unmethylated status of LTE and H460 cells after X-ray irradiation (Figure 2A and D), while in contrast, methylation of the Axin gene was decreased along with an associated increase in unmethylated sequences in the promoter and first intron regions of the H446 cell line, which has an intrinsic hypermethylated Axin gene (P<0.05) (Figure 2C). Although demethylation of the promoter and first intron regions in the H157 cell line was not detected (data not shown), a significant demethylation in the second intron region could be observed in this cell line after X-ray irradiation (P<0.05) (Figure 2B). These results suggest that X-ray irradiation may induce Axin expression via demethylating the DNA in lung cancer cells.


Axin gene methylation status correlates with radiosensitivity of lung cancer cells.

Yang LH, Han Y, Li G, Xu HT, Jiang GY, Miao Y, Zhang XP, Zhao HY, Xu ZF, Stoecker M, Wang E, Xu K, Wang EH - BMC Cancer (2013)

The effect of X-ray irradiation on methylation status of the Axin gene in lung cancer cell lines. There is no obvious change in unmethylated status of the Axin promoter and first intron in the LTE (A) and H460 (D) cell lines after X-ray irradiation, while significant demethylation could be detected in the second intron of H157 cells (B) and the promoter and first intron in H446 cells (C).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750238&req=5

Figure 2: The effect of X-ray irradiation on methylation status of the Axin gene in lung cancer cell lines. There is no obvious change in unmethylated status of the Axin promoter and first intron in the LTE (A) and H460 (D) cell lines after X-ray irradiation, while significant demethylation could be detected in the second intron of H157 cells (B) and the promoter and first intron in H446 cells (C).
Mentions: MSP demonstrated that there was no change of the unmethylated status of LTE and H460 cells after X-ray irradiation (Figure 2A and D), while in contrast, methylation of the Axin gene was decreased along with an associated increase in unmethylated sequences in the promoter and first intron regions of the H446 cell line, which has an intrinsic hypermethylated Axin gene (P<0.05) (Figure 2C). Although demethylation of the promoter and first intron regions in the H157 cell line was not detected (data not shown), a significant demethylation in the second intron region could be observed in this cell line after X-ray irradiation (P<0.05) (Figure 2B). These results suggest that X-ray irradiation may induce Axin expression via demethylating the DNA in lung cancer cells.

Bottom Line: The mechanisms, however, were not clear.Real-time PCR was used to quantify the expression of Axin, and western blot analysis was applied to measure protein levels of Axin, β-catenin, Cyclin D1, MMP-7, DNMTS, MeCP2 and acetylated histones.Hypermethylated Axin gene was detected in 2 of 4 cell lines, and it correlated inversely with Axin expression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China.

ABSTRACT

Background: We previously reported that Axin1 (Axin) is down-regulated in many cases of lung cancer, and X-ray irradiation increased Axin expression and inhibited lung cancer cells. The mechanisms, however, were not clear.

Methods: Four lung cancer cell lines were used to detect the methylation status of Axin with or without X-ray treatment. Real-time PCR was used to quantify the expression of Axin, and western blot analysis was applied to measure protein levels of Axin, β-catenin, Cyclin D1, MMP-7, DNMTS, MeCP2 and acetylated histones. Flow cytometric analysis, colony formation assay, transwell assay and xenograft growth experiment were used to study the biological behavior of the cells with hypermethylated or unmethylated Axin gene after X-ray treatment.

Results: Hypermethylated Axin gene was detected in 2 of 4 cell lines, and it correlated inversely with Axin expression. X-ray treatment significantly up-regulated Axin expression in H446 and H157 cells, which possess intrinsic hypermethylation of the Axin gene (P<0.01), but did not show up-regulation in LTE and H460 cells, which have unmethylated Axin gene. 2Gy X-ray significantly reduced colony formation (from 71% to 10.5%) in H157 cells, while the reduction was lower in LTE cells (from 71% to 20%). After X-ray irradiation, xenograft growth was significantly decreased in H157 cells (from 1.15 g to 0.28 g) in comparison with LTE cells (from 1.06 g to 0.65 g). Significantly decreased cell invasiveness and increased apoptosis were also observed in H157 cells treated with X-ray irradiation (P<0.01). Down-regulation of DNMTs and MeCP2 and up-regulation of acetylated histones could be detected in lung cancer cells.

Conclusions: X-ray-induced inhibition of lung cancer cells may be mediated by enhanced expression of Axin via genomic DNA demethylation and histone acetylation. Lung cancer cells with a different methylation status of the Axin gene showed different radiosensitivity, suggesting that the methylation status of the Axin gene may be one important factor to predict radiosensitivity of the tumor.

Show MeSH
Related in: MedlinePlus