Kuonen, François Laurent, Julien Secondini, Chiara Lorusso, Girieca Stehle, Jean-Christophe Rausch, Thierry Hull, Eveline Faes-van't Bieler, Gregory Alghisi, Gian Carlo Schwendener, Reto A. Andrejevic-Blant, Snezana Mirimanoff, René-Olivier Rüegg, Curzio 2012-06-08 Purpose: Local breast cancer relapse after breast-saving surgery and radiotherapy is associated with increased risk of distant metastasis formation. The mechanisms involved remain largely elusive. We used the well-characterized 4T1 syngeneic, orthotopic breast cancer model to identify novel mechanisms of post-radiation metastasis. Experimental Design: 4T1 cells were injected in 20 Gy pre-irradiated mammary tissue, to mimic post-radiation relapses, or in non-irradiated mammary tissue, as control, of immunocompetent BALB/c mice. Molecular, biochemical, cellular, histological analyses, adoptive cell transfer, genetic and pharmacological interventions were performed. Results: Tumors growing in pre-irradiated mammary tissue had reduced angiogenesis, were more hypoxic, invasive and metastatic to lung and lymph nodes compared to control tumors. Increased metastasis involved the mobilization of CD11b+c-Kit+Ly6GhighLy6Clow(Gr1+) myeloid cells through the HIF1-dependent expression of KitL by hypoxic tumor cells. KitL-mobilized myeloid cells homed to primary tumors and pre-metastatic lungs, to give rise to CD11b+c-Kit- cells. Pharmacological inhibition of HIF1, silencing of KitL expression in tumor cells and inhibition of c-Kit with an anti-c-Kit blocking antibody or with a tyrosine kinase inhibitor, prevented the mobilization of CD11b+c-Kit+ cells and attenuated metastasis. C-Kit inhibition was also effective in reducing mobilization of CD11b+c-Kit+ cells and inhibiting lung metastasis after irradiation of established tumors. Conclusions: Our work defines KitL/c-Kit as a previously unidentified axis critically involved in promoting metastasis of 4T1 tumors growing in pre-irradiated mammary tissue. Pharmacological inhibition of this axis represents a potential therapeutic strategy to prevent metastasis in breast cancer patients with local relapses after radiotherapy. application/pdf https://folia.unifr.ch/global/documents/302449 https://folia.unifr.ch/documents/302449/files/rue_ikl.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1158/1078-0432.ccr-11-3028 info:eu-repo/semantics/openAccess License undefined Clinical Cancer Research. - 2012, vol. 18, no. 16, p. 4365-4374 info:eu-repo/classification/udc/57 Inhibition of the Kit ligand/c-Kit axis attenuates metastasis in a mouse model mimicking local breast cancer relapse after radiotherapy http://purl.org/coar/resource_type/c_6501