Tumor resistance, recurrence and metastasis are the primary causes of the failure of cancer treatments. Although extensively studied, the fundamental mechanism underlying the aggressive therapy-resistant tumor phenotype remains to be a major challenge in improving overall cancer cure rate. NF-kB-mediated pro-survival networks are shown to be important mediators of increased survival and radioresistance in breast cancer cells that survive a long- term fractionated irradiation. Recent new evidence further indicate that NF-kB-induces the expression of MAPK phosphatase 1 (MKP1) that is capable of inhibiting apoptosis by attenuating mitochondria-mediated apoptosis in radiation-resistant breast cancer cells. Data provided in this proposal indicate that MKP1 locates in the mitochondria and radiation enhances its mitochondrial influx resulting in the reduction of its substrate JNK phosphorylation, a key event in mitochondria-mediated apoptosis. In addition, breast cancer + -/low stem cells (CSCs with CD44 /CD24) have been identified to be radioresistant and enriched in the surviving fraction of breast cancer cells irradiated with fractionated irradiation. In this study, we propose to elucidate the signaling network of MKP1-mediated anti- mitochondrial apoptosis response in radiation-derived radioresistant breast cancer cell lines. We will investigate whether MKP1-mediated anti-apoptotic response is specifically activated in breast cancer stem cells that are believed to be radioresistant and enriched in the recurrent and metastatic tumor of cancer patients. The hypothesis to be tested is that MKP1- mitochondrial translocation inhibits mitochondrial JNK activity and mitochondria-dependent apoptosis in radioresistant breast CSCs. There are Three Specific Aims: 1, Test whether mitochondrial translocation of MKP1 is responsible for tumor radioresistance;2, Elucidate the molecular mechanisms upstream of MKP1 activation leading to the inhibition of apoptosis;and 3, Detect ERK/MKP1-mediated pro-survival response in radioresistant + -/low CD44 /CD24 breast cancer stem cells in recurrent/metastatic tumors.

Public Health Relevance

Identification of MKP1-mediated radioresistant pathway in breast cancer cells, especially revealing the mechanism of radioresistant breast cancer stem cells, will provide important information in therapy-associated tumor resistance and invent next generation of anti-cancer agents for therapy-resistant breast cancer cells in the recurrent and metastatic tumors.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA152313-04
Application #
8634735
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Bernhard, Eric J
Project Start
2011-04-08
Project End
2016-03-31
Budget Start
2014-04-01
Budget End
2015-03-31
Support Year
4
Fiscal Year
2014
Total Cost
$361,285
Indirect Cost
$120,658
Name
University of California Davis
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
047120084
City
Davis
State
CA
Country
United States
Zip Code
95618
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Liu, Rui; Fan, Ming; Candas, Demet et al. (2015) CDK1-Mediated SIRT3 Activation Enhances Mitochondrial Function and Tumor Radioresistance. Mol Cancer Ther 14:2090-102
Nantajit, Danupon; Lin, Dong; Li, Jian Jian (2015) The network of epithelial-mesenchymal transition: potential new targets for tumor resistance. J Cancer Res Clin Oncol 141:1697-713
Lu, Chung-Ling; Qin, Lili; Liu, Hsin-Chen et al. (2015) Tumor cells switch to mitochondrial oxidative phosphorylation under radiation via mTOR-mediated hexokinase II inhibition--a Warburg-reversing effect. PLoS One 10:e0121046
Cui, Yang; Qin, Lili; Wu, Jing et al. (2015) SIRT3 Enhances Glycolysis and Proliferation in SIRT3-Expressing Gastric Cancer Cells. PLoS One 10:e0129834
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Qin, Lili; Fan, Ming; Candas, Demet et al. (2015) CDK1 Enhances Mitochondrial Bioenergetics for Radiation-Induced DNA Repair. Cell Rep 13:2056-63
Jin, Cuihong; Qin, Lili; Shi, Yan et al. (2015) CDK4-mediated MnSOD activation and mitochondrial homeostasis in radioadaptive protection. Free Radic Biol Med 81:77-87

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