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Title: Vasculatures in Tumors Growing From Preirradiated Tissues: Formed by Vasculogenesis and Resistant to Radiation and Antiangiogenic Therapy

Journal Article · · International Journal of Radiation Oncology, Biology and Physics
;  [1];  [2];  [1];  [2];  [3];  [4];  [5];  [2]
  1. Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Taiwan (China)
  2. Department of Radiation Oncology, Chang Gung Memorial Hospital-LinKou, Taiwan (China)
  3. Department of Pathology, Chang Gung Memorial Hospital-LinKou, Taiwan (China)
  4. Animal Molecular Imaging Center, Chang Gung Memorial Hospital-LinKou, Taiwan (China)
  5. Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taiwan (China)

Purpose: To investigate vasculatures and microenvironment in tumors growing from preirradiated tissues (pre-IR tumors) and study the vascular responses of pre-IR tumors to radiation and antiangiogenic therapy. Methods and Materials: Transgenic adenocarcinoma of the mouse prostate C1 tumors were implanted into unirradiated or preirradiated tissues and examined for vascularity, hypoxia, and tumor-associated macrophage (TAM) infiltrates by immunohistochemistry. The origin of tumor endothelial cells was studied by green fluorescent protein-tagged bone marrow (GFP-BM) transplantation. The response of tumor endothelial cells to radiation and antiangiogenic agent was evaluated by apoptotic assay. Results: The pre-IR tumors had obvious tumor bed effects (TBE), with slower growth rate, lower microvascular density (MVD), and more necrotic and hypoxic fraction compared with control tumors. The vessels were dilated, tightly adhered with pericytes, and incorporated with transplanted GFP-BM cells. In addition, hypoxic regions became aggregated with TAM. As pre-IR tumors developed, the TBE was overcome at the tumor edge where the MVD increased, TAM did not aggregate, and the GFP-BM cells did not incorporate into the vessels. The vessels at tumor edge were more sensitive to the following ionizing radiation and antiangiogenic agent than those in the central low MVD regions. Conclusions: This study demonstrates that vasculatures in regions with TBE are mainly formed by vasculogenesis and resistant to radiation and antiangiogenic therapy. Tumor bed effects could be overcome at the edge of larger tumors, but where vasculatures are formed by angiogenesis and sensitive to both treatments. Vasculatures formed by vasculogenesis should be the crucial target for the treatment of recurrent tumors after radiotherapy.

OSTI ID:
21587638
Journal Information:
International Journal of Radiation Oncology, Biology and Physics, Vol. 80, Issue 5; Other Information: DOI: 10.1016/j.ijrobp.2011.02.055; PII: S0360-3016(11)00453-6; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
Country of Publication:
United States
Language:
English