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Abstract PD02-10: Radiation Induces Notch-Dependent De Novo Generation of Breast Cancer Stem Cells. Cancer Res 2010. [DOI: 10.1158/0008-5472.sabcs10-pd02-10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Like in normal tissues, the self-renewal of cancer stem cells (CSCs) might be also under tight control of developmental pathway like the Notch, Wnt, Sonic Hedgehog or TGFβ pathways. The Notch pathway plays an important role in normal breast development, cell fate, and normal stem cell self-renewal, and its deregulation has been shown to play a role in cancer. Aberrant Notch signaling has been implicated in the development and progression of both preinvasive ductal carcinomas in situ and invasive. Interestingly, in breast cancer, the Notch pathway plays major role for CSCs maintenance. We previously published that BCSCs (Breast Cancer Stem Cells) are more resistant to radiation. Here we demonstrate a link between BCSCs radio-resistance and the Notch pathway. We show that irradiation of MCF-7 cells increases CSC numbers and that this correlates with an induction of Notch signaling proteins expression in a dose and time specific manner. Jagged 1 was quickly (1h) increased 28-fold after 2Gy, DLL1 was increased 15-fold after 3 to 6h of 2 and 4 Gy irradiation, and Notch 2 was increased 16-fold 6h after 2, 4, 6 or 8 Gy, while DLL3 was increased 10-fold after the highest doses (6 to 12 Gy). Inhibition of Notch signaling pathway by the γ-secretase inhibitor prevents enrichment for CSCs and reduces radiation-induced overexpression of Notch proteins. More interestingly, we demonstrated that radiation-induced Notch signaling contributes to the phenotype plasticity of BCSCs and their progeny. Therefore, ionizing radiation induces de novo generation of BCSCs from non-tumorigenic cells. Moreover, we also identified, by FACS analysis, an induction of polyploid CSCs. expressed a relatively higher level of Oct4 and Sox2 than the unirradiated non-CSCs (two key transcription factors involved in stemness maintenance). In summary, we provide evidence that radiation-induced Notch signaling contributes to the plasticity of the BCSC phenotype, thereby generating BCSCs de novo from non-tumorigenic cells. Our data suggest that stochastic as well hierarchical CSC models apply to breast cancer.
Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD02-10.
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