Colorectal cancer (CRC) is one of the most common cancers; however, the development of drugs to treat the condition has reached a plateau. Bortezomib (PS-341, Velcade®) is a proteasome inhibitor approved for the treatment of hematological malignancies, including multiple myeloma.
A few trials of bortezomib, alone or in combination chemotherapy, for CRC patients have been reported; however, the results were largely inconclusive. This may be related to a lack of understanding of the drug's mechanism of action. Although bortezomib is reported to induce apoptosis and cell
cycle arrest in various human cancer cells, the inhibitory mechanism involved is not clear. In this study, the effect of bortezomib as a treatment for human CRC was examined in vitro using three CRC cell lines. Bortezomib induced G2-M arrest in CRC cells. Investigation of G2-M phase-related
cell cycle proteins involved in the response to bortezomib revealed that the ataxia telangiectasia mutated (ATM)-cell cycle checkpoint kinase 1 (CHK1) pathway, but not ATM and Rad3-related (ATR), was activated, resulting in the inactivation of cdc2. Bortezomib caused an increase in intracellular
reactive oxygen species (ROS) and treatment with the ROS scavenger NAC inhibited phosphorylation of ATM leading to a decrease in the number of cells in G2-M phase. Thus, increased ROS levels after exposure to bortezomib resulted in ATM phosphorylation. In addition, knockdown of endogenous
ATM by RNA interference resulted in decreased sensitivity to bortezomib. These results suggest that bortezomib induces G2-M arrest through ROS-inducible ATM phosphorylation and demonstrate that bortezomib is a potential candidate for further investigations in the treatment for CRC patients.
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Document Type: Research Article
Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
Institute for Innovative Cancer Research, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
Department of Internal Medicine, Cancer Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
Publication date: January 1, 2012
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The International Journal of Oncology provides an international forum for the publication of the latest, cutting-edge research in the broad area of oncology and cancer treatment. The journal accepts original high quality works and reviews on all aspects of oncology research including carcinogenesis, metastasis, epidemiology, chemotherapy and viral oncology. Through fair and efficient peer review, the journal is dedicated to publishing top tier research in the field, offering authors rapid publication as well as high standards of copy-editing and production. The International Journal of Oncology is published on a monthly basis in both print and early online.
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