TY - JOUR
T1 - CSF1R signaling blockade stanches tumor-infiltrating myeloid cells and improves the efficacy of radiotherapy in prostate cancer
AU - Xu, Jingying
AU - Escamilla, Jemima
AU - Mok, Stephen
AU - David, John
AU - Priceman, Saul
AU - West, Brian
AU - Bollag, Gideon
AU - McBride, William
AU - Wu, Lily
PY - 2013/5/1
Y1 - 2013/5/1
N2 - Radiotherapy is used to treat many types of cancer, but many treated patients relapse with local tumor recurrence. Tumor-infiltrating myeloid cells (TIM), including CD11b (ITGAM)+F4/80 (EMR1)+ tumorassociated macrophages (TAM), and CD11b+Gr-1 (LY6G)+ myeloid-derived suppressor cells (MDSC), respond to cancer-related stresses and play critical roles in promoting tumor angiogenesis, tissue remodeling, and immunosuppression. In this report, we used a prostate cancer model to investigate the effects of irradiation on TAMs and MDSCs in tumor-bearing animals. Unexpectedly, when primary tumor sites were irradiated, we observed a systemic increase of MDSCs in spleen, lung, lymph nodes, and peripheral blood. Cytokine analysis showed that the macrophage colony-stimulating factor CSF1 increased by two-fold in irradiated tumors. Enhanced macrophage migration induced by conditioned media from irradiated tumor cells was completely blocked by a selective inhibitor of CSF1R. These findings were confirmed in patients with prostate cancer, where serum levels of CSF1 increased after radiotherapy. Mechanistic investigations revealed the recruitment of the DNA damage-induced kinase ABL1 into cell nuclei where it bound the CSF1 gene promoter and enhanced CSF1 gene transcription. When added to radiotherapy, a selective inhibitor of CSF1R suppressed tumor growth more effectively than irradiation alone. Our results highlight the importance of CSF1/CSF1R signaling in the recruitment of TIMs that can limit the efficacy of radiotherapy. Furthermore, they suggest that CSF1 inhibitors should be evaluated in clinical trials in combination with radiotherapy as a strategy to improve outcomes. Cancer Res; 73(9); 2782-94.
AB - Radiotherapy is used to treat many types of cancer, but many treated patients relapse with local tumor recurrence. Tumor-infiltrating myeloid cells (TIM), including CD11b (ITGAM)+F4/80 (EMR1)+ tumorassociated macrophages (TAM), and CD11b+Gr-1 (LY6G)+ myeloid-derived suppressor cells (MDSC), respond to cancer-related stresses and play critical roles in promoting tumor angiogenesis, tissue remodeling, and immunosuppression. In this report, we used a prostate cancer model to investigate the effects of irradiation on TAMs and MDSCs in tumor-bearing animals. Unexpectedly, when primary tumor sites were irradiated, we observed a systemic increase of MDSCs in spleen, lung, lymph nodes, and peripheral blood. Cytokine analysis showed that the macrophage colony-stimulating factor CSF1 increased by two-fold in irradiated tumors. Enhanced macrophage migration induced by conditioned media from irradiated tumor cells was completely blocked by a selective inhibitor of CSF1R. These findings were confirmed in patients with prostate cancer, where serum levels of CSF1 increased after radiotherapy. Mechanistic investigations revealed the recruitment of the DNA damage-induced kinase ABL1 into cell nuclei where it bound the CSF1 gene promoter and enhanced CSF1 gene transcription. When added to radiotherapy, a selective inhibitor of CSF1R suppressed tumor growth more effectively than irradiation alone. Our results highlight the importance of CSF1/CSF1R signaling in the recruitment of TIMs that can limit the efficacy of radiotherapy. Furthermore, they suggest that CSF1 inhibitors should be evaluated in clinical trials in combination with radiotherapy as a strategy to improve outcomes. Cancer Res; 73(9); 2782-94.
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U2 - 10.1158/0008-5472.CAN-12-3981
DO - 10.1158/0008-5472.CAN-12-3981
M3 - Article
C2 - 23418320
AN - SCOPUS:84877738839
SN - 0008-5472
VL - 73
SP - 2782
EP - 2794
JO - Cancer Research
JF - Cancer Research
IS - 9
ER -