Macrophages From Irradiated Tumors Express Higher Levels of iNOS, Arginase-I and COX-2, and Promote Tumor Growth
- Department of Radiation Oncology, Chang Gung Memorial Hospital and Chang Gung University, Taiwan (China)
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Taiwan (China)
- Department of Pathology, Chang Gung University, Taiwan (China)
- Department of Medical Imaging and Radiological Science, Chang Gung University, Taiwan (China)
- Department of Radiation Oncology, Roy E. Coats Laboratories, University of California Los Angeles, Los Angeles, CA (United States)
- Department of Radiation Oncology, Chang Gung Memorial Hospital and Chang Gung University, Taiwan (China) and Department of Medical Imaging and Radiological Science, Chang Gung University, Taiwan (China)
Purpose: To investigate the effects of single and fractionated doses of radiation on tumors and tumor-associated macrophages (TAMs), and to elucidate the potential of TAMs to influence tumor growth. Methods and Materials: A murine prostate cell line, TRAMP-C1, was grown in C57Bl/6J mice to 4-mm tumor diameter and irradiated with either 25 Gy in a single dose, or 60 Gy in 15 fractions. The tumors were removed at the indicated times and assessed for a variety of markers related to TAM content, activation status, and function. Results: In tumors receiving a single radiation dose, arginase (Arg-I), and cycloxygenase-2 (COX-2) mRNA expression increased as a small transient wave within 24 h and a larger persistent wave starting after 3 days. Inducible nitric oxide synthase (iNOS) mRNA was elevated only after 3 days and continued to increase up to 3 weeks. After fractionated irradiation, Arg-1 and COX-2 mRNA levels increased within 5 days, whereas iNOS was increased only after 10 fractions of irradiation had been given. Increased levels of Arg-I, COX-2, and, to a lesser extent, iNOS protein were found to associate with TAMs 1-2 weeks after tumor irradiation. Function of TAMs were compared by mixing them with TRAMP-C1 cells and injecting them into mice; TRAMP-C1 cells mixed with TAMs from irradiated tumors appeared earlier and grew significantly faster than those mixed with TAMs from unirradiated tumors or TRAMP-C1 alone. Conclusions: Tumor-associated macrophages in the postirradiated tumor microenvironment express higher levels of Arg-1, COX-2, and iNOS, and promote early tumor growth in vivo.
- OSTI ID:
- 20951671
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 68, Issue 2; Other Information: DOI: 10.1016/j.ijrobp.2007.01.041; PII: S0360-3016(07)00232-5; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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