Abstract
Purpose To characterize the recruitment of bone marrow (BM)-derived hematopoietic stem and progenitor cells (HSPCs) within tumor microenvironment after radiation therapy (RT) in a murine, heterotopic tumor model. Methods and Materials Lewis lung carcinoma tumors were established in C57BL/6 mice and irradiated with 30 Gy given as 2 fractions over 2 days. Tumors were imaged with positron emission tomography/computed tomography (PET/CT) and measured daily with digital calipers. The HSPC and myelomonocytic cell content was assessed via immunofluorescent staining and flow cytometry. Functionality of tumor-associated HSPCs was verified in vitro using colony-forming cell assays and in vivo by rescuing lethally irradiated C57BL/6 recipients. Results Irradiation significantly reduced tumor volumes and tumor regrowth rates compared with nonirradiated controls. The number of CD133+ HSPCs present in irradiated tumors was higher than in nonirradiated tumors during all stages of regrowth. CD11b+ counts were similar. PET/CT imaging and growth rate analysis based on standardized uptake value indicated that HSPC recruitment directly correlated to the extent of regrowth and intratumor cell activity after irradiation. The BM-derived tumor-associated HSPCs successfully formed hematopoietic colonies and engrafted irradiated mice. Finally, targeted treatment with a small animal radiation research platform demonstrated localized HSPC recruitment to defined tumor subsites exposed to radiation. Conclusions Hypofractionated irradiation resulted in a pronounced and targeted recruitment of BM-derived HSPCs, possibly as a mechanism to promote tumor regrowth. These data indicate for the first time that radiation therapy regulates HSPC content within regrowing tumors.
Original language | English (US) |
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Pages (from-to) | 1162-1170 |
Number of pages | 9 |
Journal | International Journal of Radiation Oncology Biology Physics |
Volume | 87 |
Issue number | 5 |
DOIs | |
State | Published - Dec 1 2013 |
Externally published | Yes |
ASJC Scopus subject areas
- Radiation
- Oncology
- Radiology Nuclear Medicine and imaging
- Cancer Research