| Autor: |
Pelosof, Lorraine, Yerram, Sashidhar, Armstrong, Todd, Chu, Nina, Danilova, Ludmila, Yanagisawa, Breann, Hidalgo, Manuel, Azad, Nilofer, Herman, James G. |
| Zdroj: |
Epigenetics; July 2017, Vol. 12 Issue: 7 p540-550, 11p |
| Abstrakt: |
ABSTRACTEpigenetic control of gene expression is a major determinant of tumor phenotype and has been found to influence sensitivity to individual chemotherapeutic agents. Glutathione peroxidase 3 (GPX3, plasma glutathione peroxidase) is a key component of cellular antioxidant regulation and its gene has been reported to be methylated in specific tumor types. GPX3 role in oxidative damage has been associated with sensitivity to platinums in other tumors but its importance in colorectal cancer (CRC) has not been determined. We examined the role of GPX3methylation in colorectal carcinoma in determining sensitivity to platinum drugs using primary tumor specimens, cell lines, knockdown cell lines, and tumor cell line xenografts. We find GPX3promoter region methylation in approximately one third of CRC samples and GPX3methylation leads to reduced GPX3 expression and increased oxaliplatin and cisplatin sensitivity. In contrast, in cell lines with high baseline levels of GPX3expression or with the ability to increase GPX3expression, platinum resistance is increased. The cisplatin IC50in GPX3-methylated cell lines is approximately 6-fold lower than that in GPX3-unmethylated lines. Additionally, knockdown cell lines with essentially no GPX3expression require N-acetylcysteine to survive in culture underscoring the importance of GPX3 in redox biology. In vivo, GPX3methylation predicts tumor xenograft sensitivity to platinum with regression of GPX3knockdown xenografts with platinum treatment but continued growth of GPX3wild type xenografts in the presence of platinum. These studies demonstrate the importance of GPX3for CRC cells resistance to platinums and the potential utility of GPX3methylation status as a predictive biomarker for platinum sensitivity in CRC. |
| Databáze: |
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