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DNMT3a plays a role in switches between doxorubicin‐induced senescence and apoptosis of colorectal cancer cells
Author(s) -
Zhang Yu,
Gao Yanyan,
Zhang Guoping,
Huang Shuyan,
Dong Zhixiong,
Kong Chenfei,
Su Dongmei,
Du Juan,
Zhu Shan,
Liang Qian,
Zhang Jianchao,
Lu Jun,
Huang Baiqu
Publication year - 2010
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.25365
Subject(s) - senescence , apoptosis , downregulation and upregulation , doxorubicin , cancer research , dna methylation , dna damage , biology , microbiology and biotechnology , chemistry , gene expression , dna , chemotherapy , biochemistry , genetics , gene
Abstract The DNA‐damaging drug doxorubicin (Dox) induces cell senescence at concentrations significantly lower than those required for induction of apoptosis. At low Dox concentrations, tumor suppressor p53 is activated, which enhances the expression of p21 Waf1/Cip1 (p21). At high concentrations, Dox activates p53 leading to apoptosis without enhancing p21 expression. The underlying mechanisms and factors that govern the differential effects of Dox in inducing senescence and apoptosis are unclear. Here, we report that the DNA methyltransferase (DNMT) DNMT3a was upregulated by Dox especially at concentrations that induced apoptosis in HCT116 colorectal cancer cells, and this process was regulated by p53. Meanwhile, p21 expression was significantly upregulated at senescence‐inducing concentrations and kept low on treatment with apoptosis‐inducing concentrations of Dox. The differential expression of DNMT3a and p21 in response to Dox suggests that DNMT3a may be a key factor in switches between Dox‐induced senescence and apoptosis. Moreover, when DNMT3a was silenced, treatment of HCT116 cells with apoptosis‐inducing concentration of Dox increased the percentage of cells undergoing senescence, accompanied by upregulation of p21. Contrarily, senescence‐inducing concentration of Dox promoted apoptosis rate, and p21 expression was repressed. Surprisingly, no changes in DNA methylation status at p21 promoter were detected at either ranges of Dox, although DNMT3a and HDAC1 were recruited to p21 promoter at apoptosis‐inducing Dox concentration, where they were present in the same complex. Overall, these data demonstrate that DNMT3a impacts the expression of p21 and plays a role in determining the Dox‐induced senescence and apoptosis in HCT116 cells.