Ataxia telangiectasia-mutated and p53 are potential mediators of chloroquine-induced resistance to mammary carcinogenesis

The use of agents to prevent the onset of and/or the progression to breast cancer has the potential to lower breast cancer risk. We have previously shown that the tumor-suppressor gene p53 is a potential mediator of hormone (estrogen/progesterone)-induced protection against chemical carcinogen-induc...

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Bibliographic Details
Published in:Cancer research (Chicago, Ill.) Ill.), 2007-12, Vol.67 (24), p.12026-12033
Main Authors: Loehberg, Christian R, Thompson, Tiia, Kastan, Michael B, Maclean, Kirsteen H, Edwards, Dean G, Kittrell, Frances S, Medina, Daniel, Conneely, Orla M, O'Malley, Bert W
Format: Article
Language:English
Subjects:
Animals
Ataxia Telangiectasia Mutated Proteins
Breast - cytology
Breast - physiology
Cell Cycle Proteins - genetics
Cell Cycle Proteins - physiology
Chloroquine - pharmacology
DNA-Binding Proteins - genetics
DNA-Binding Proteins - physiology
Drug Resistance, Neoplasm
Epithelial Cells - cytology
Epithelial Cells - physiology
Female
Genes, p53
Humans
Mammary Neoplasms, Animal - genetics
Mammary Neoplasms, Animal - prevention & control
Mice
Mice, Inbred BALB C
Mice, Knockout
Protein-Serine-Threonine Kinases - genetics
Protein-Serine-Threonine Kinases - physiology
Tumor Suppressor Protein p53 - deficiency
Tumor Suppressor Protein p53 - genetics
Tumor Suppressor Proteins - genetics
Tumor Suppressor Proteins - physiology
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Summary:The use of agents to prevent the onset of and/or the progression to breast cancer has the potential to lower breast cancer risk. We have previously shown that the tumor-suppressor gene p53 is a potential mediator of hormone (estrogen/progesterone)-induced protection against chemical carcinogen-induced mammary carcinogenesis in animal models. Here, we show for the first time a breast cancer-protective effect of chloroquine in an animal model. Chloroquine significantly reduced the incidence of N-methyl-N-nitrosourea-induced mammary tumors in our animal model similar to estrogen/progesterone treatment. No protection was seen in our BALB/c p53-null mammary epithelium model, indicating a p53 dependency for the chloroquine effect. Using a human nontumorigenic mammary gland epithelial cell line, MCF10A, we confirm that in the absence of detectable DNA damage, chloroquine activates the tumor-suppressor p53 and the p53 downstream target gene p21, resulting in G(1) cell cycle arrest. p53 activation occurs at a posttranslational level via chloroquine-dependent phosphorylation of the checkpoint protein kinase, ataxia telangiectasia-mutated (ATM), leading to ATM-dependent phosphorylation of p53. In primary mammary gland epithelial cells isolated from p53-null mice, chloroquine does not induce G(1) cell cycle arrest compared with cells isolated from wild-type mice, also indicating a p53 dependency. Our results indicate that a short prior exposure to chloroquine may have a preventative application for mammary carcinogenesis.
ISSN:0008-5472
1538-7445
DOI:10.1158/0008-5472.can-07-3058