期刊
BMC CANCER
卷 14, 期 -, 页码 -出版社
BMC
DOI: 10.1186/1471-2407-14-532
关键词
Lysyl oxidase; Ionizing radiation; Tumor invasion; Radiation resistance; Hypoxia; Microtubule stabilizing agent
类别
资金
- Whitaker International Fellows and Scholars Program
- Vontobel Stiftung
- Fonds fur Medizinische Forschung University Zurich, Krebsforschung Schweiz
- Swiss National Science Foundations
- Hallas Moller Stipendum from the Novo Nordisk Foundation
- Novo Nordisk Fonden [NNF12OC1015992] Funding Source: researchfish
Background: Ionizing radiation (IR) is a mainstay of cancer therapy, but irradiation can at times also lead to stress responses, which counteract IR-induced cytotoxicity. IR also triggers cellular secretion of vascular endothelial growth factor, transforming growth factor beta and matrix metalloproteinases, among others, to promote tumor progression. Lysyl oxidase is known to play an important role in hypoxia-dependent cancer cell dissemination and metastasis. Here, we investigated the effects of IR on the expression and secretion of lysyl oxidase (LOX) from tumor cells. Methods: LOX-secretion along with enzymatic activity was investigated in multiple tumor cell lines in response to irradiation. Transwell migration assays were performed to evaluate invasive capacity of naive tumor cells in response to IR-induced LOX. In vivo studies for confirming IR-enhanced LOX were performed employing immunohistochemistry of tumor tissues and ex vivo analysis of murine blood serum derived from locally irradiated A549-derived tumor xenografts. Results: LOX was secreted in a dose dependent way from several tumor cell lines in response to irradiation. IR did not increase LOX-transcription but induced LOX-secretion. LOX-secretion could not be prevented by the microtubule stabilizing agent patupilone. In contrast, hypoxia induced LOX-transcription, and interestingly, hypoxia-dependent LOX-secretion could be counteracted by patupilone. Conditioned media from irradiated tumor cells promoted invasiveness of nai've tumor cells, while conditioned media from irradiated, LOX-siRNA-silenced cells did not stimulate their invasive capacity. Locally applied irradiation to tumor xenografts also increased LOX-secretion in vivo and resulted in enhanced LOX-levels in the murine blood serum. Conclusions: These results indicate a differential regulation of LOX-expression and secretion in response to IR and hypoxia, and suggest that LOX may contribute towards an IR-induced migratory phenotype in sublethally-irradiated tumor cells and tumor progression.
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