RAC1 GTPase plays an important role in γ-irradiation induced G2/M checkpoint activation
| Autor: | Phu T. Cao, Kenneth H. Cowan, Ying Yan, Patrick M. Greer, Ryan H. Kolb |
|---|---|
| Jazyk: | angličtina |
| Předmět: |
rac1 GTP-Binding Protein
Cell Survival DNA repair MAP Kinase Kinase 2 MAP Kinase Kinase 1 Breast Neoplasms Cell Cycle Proteins Ataxia Telangiectasia Mutated Proteins Cyclin B Protein Serine-Threonine Kinases 03 medical and health sciences 0302 clinical medicine Cyclin-dependent kinase Cell Line Tumor CDC2 Protein Kinase Humans CHEK1 Enzyme Inhibitors Phosphorylation Protein kinase A 030304 developmental biology Mitogen-Activated Protein Kinase 1 Medicine(all) 0303 health sciences Cyclin-dependent kinase 1 Mitogen-Activated Protein Kinase 3 biology Kinase Tumor Suppressor Proteins G2-M DNA damage checkpoint Cyclin-Dependent Kinases 3. Good health Cell biology DNA-Binding Proteins Enzyme Activation G2 Phase Cell Cycle Checkpoints Pyrimidines Gamma Rays 030220 oncology & carcinogenesis Checkpoint Kinase 1 Aminoquinolines biology.protein M Phase Cell Cycle Checkpoints Tyrosine Female Protein Kinases Signal Transduction Research Article |
| Zdroj: | Breast Cancer Research : BCR |
| ISSN: | 1465-542X |
| DOI: | 10.1186/bcr3164 |
| Popis: | Introduction In response to gamma-irradiation (IR)-induced double-strand DNA breaks, cells undergo cell-cycle arrest, allowing time for DNA repair before reentering the cell cycle. G2/M checkpoint activation involves activation of ataxia telangiectasia mutated (ATM)/ATM- and rad3-related (ATR) kinases and inhibition of Cdc25 phosphatases, resulting in inhibition of Cdc2 kinase and subsequent G2/M cell-cycle arrest. Previous studies from our laboratory showed that the G2/M checkpoint activation after IR exposure of MCF-7 breast cancer cells is dependent on the activation of extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) signaling. In the present studies, we investigated the role of Ras-related C3 botulinum toxin substrate 1 (Rac1) guanosine triphosphatase (GTPase) in IR-induced G2/M checkpoint response and ERK1/2 activation, as well as in cell survival after IR. Methods With Rac1-specific inhibitor, dominant negative mutant Rac1 (N17Rac1) and specific small interfering RNA, the effect of Rac1 on IR-induced G2/M checkpoint response and ERK1/2 activation was examined in human breast cancer cells. In addition, the effect of Rac1 on cell survival after irradiation was assessed by using Rac1-specific inhibitor. Results IR exposure of MCF-7 breast cancer cells was associated with a marked activation of Rac1 GTPase. Furthermore, inhibition of Rac1 by using specific inhibitor, dominant-negative Rac1 mutant, or specific siRNA resulted in attenuation of IR-induced G2/M arrest and concomitant diminution of IR-induced activation of ATM, ATR, Chk1, and Chk2 kinases, as well as phosphorylation of Cdc2-Tyr15. Moreover, Rac1 inhibition or decreased Rac1 expression also abrogated IR-induced phosphorylation of mitogen-activated protein kinase kinase 1 and 2 (MEK1/2) and ERK1/2. Ultimately, inhibition of Rac1 markedly increased cellular sensitivity to IR exposure, which involves induction of apoptosis. Conclusion Studies in this report suggest that Rac1 GTPase plays an essential role in the activation of IR-induced ERK1/2 signaling and subsequent G2/M checkpoint response. Furthermore, results also support a role for Rac1 in promoting cell survival after irradiation treatment. |
| Databáze: | OpenAIRE |
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