Correlation Between Tumor Growth Delay and Expression of Cancer and Host VEGF, VEGFR2, and Osteopontin in Response to Radiotherapy

Timothy D. Solberg, Jessica Nearman, John Mullins, Sicong Li, Janina Baranowska-Kortylewicz

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Abstract

Purpose: To determine the late effects of radiotherapy (RT) on vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR2), and osteopontin (OPN) expression in cancer and stromal cells. Methods and Materials: LS174T xenografted athymic mice were used as a tumor model. Radiation was delivered in two equivalent fractionation schemes: 5 × 7 Gy and 1 × 20 Gy, the latter at two dose rates. Results: Tumor growth arrest was similar in all treatment groups, with the exception of a better response of small-size tumors in the 5 × 7-Gy group. The host VEGF and OPN levels were directly proportional to the tumor doubling time and were independent of the fractionation scheme. The host and cancer cell VEGFR2 levels in tumor were also directly related to the tumor response to RT. Conclusion: Upregulated VEGFR2 in cancer cells suggest paracrine signaling in the VEGFR2 pathway of cancer cells as the factor contributing to RT failure. The transient activation of the host VEGF/VEGFR2 pathway in tumor supports the model of angiogenic regeneration and suggests that radiation-induced upregulation of VEGF, VEGFR2, and downstream proteins might contribute to RT failure by escalating the rate of vascular repair. Coexpression of host OPN and VEGF, two factors closely associated with angiogenesis, indicate that OPN can serve as a surrogate marker of tumor recovery after RT. Taken together, these results strongly support the notion that to achieve optimal therapeutic outcomes, the scheduling of RT and antiangiogenic therapies will require patient-specific post-treatment monitoring of the VEGF/VEGFR2 pathway and that tumor-associated OPN can serve as an indicator of tumor regrowth.

Original languageEnglish (US)
Pages (from-to)918-926
Number of pages9
JournalInternational Journal of Radiation Oncology Biology Physics
Volume72
Issue number3
DOIs
StatePublished - Nov 1 2008

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Vascular Endothelial Growth Factor Receptor-2
Vascular Endothelial Growth Factor Receptor
Osteopontin
radiation therapy
Radiotherapy
tumors
cancer
Growth
Neoplasms
Vascular Endothelial Growth Factor A
fractionation
angiogenesis
scheduling
radiation
Paracrine Communication
Radiation
regeneration
markers
mice
therapy

Keywords

  • Osteopontin
  • Stereotactic body radiotherapy
  • VEGF
  • VEGFR2
  • Vascular endothelial growth factor

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

Cite this

@article{12c9632a98da417b9038f88b8c624ad1,
title = "Correlation Between Tumor Growth Delay and Expression of Cancer and Host VEGF, VEGFR2, and Osteopontin in Response to Radiotherapy",
abstract = "Purpose: To determine the late effects of radiotherapy (RT) on vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR2), and osteopontin (OPN) expression in cancer and stromal cells. Methods and Materials: LS174T xenografted athymic mice were used as a tumor model. Radiation was delivered in two equivalent fractionation schemes: 5 × 7 Gy and 1 × 20 Gy, the latter at two dose rates. Results: Tumor growth arrest was similar in all treatment groups, with the exception of a better response of small-size tumors in the 5 × 7-Gy group. The host VEGF and OPN levels were directly proportional to the tumor doubling time and were independent of the fractionation scheme. The host and cancer cell VEGFR2 levels in tumor were also directly related to the tumor response to RT. Conclusion: Upregulated VEGFR2 in cancer cells suggest paracrine signaling in the VEGFR2 pathway of cancer cells as the factor contributing to RT failure. The transient activation of the host VEGF/VEGFR2 pathway in tumor supports the model of angiogenic regeneration and suggests that radiation-induced upregulation of VEGF, VEGFR2, and downstream proteins might contribute to RT failure by escalating the rate of vascular repair. Coexpression of host OPN and VEGF, two factors closely associated with angiogenesis, indicate that OPN can serve as a surrogate marker of tumor recovery after RT. Taken together, these results strongly support the notion that to achieve optimal therapeutic outcomes, the scheduling of RT and antiangiogenic therapies will require patient-specific post-treatment monitoring of the VEGF/VEGFR2 pathway and that tumor-associated OPN can serve as an indicator of tumor regrowth.",
keywords = "Osteopontin, Stereotactic body radiotherapy, VEGF, VEGFR2, Vascular endothelial growth factor",
author = "Solberg, {Timothy D.} and Jessica Nearman and John Mullins and Sicong Li and Janina Baranowska-Kortylewicz",
year = "2008",
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doi = "10.1016/j.ijrobp.2008.06.1925",
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T1 - Correlation Between Tumor Growth Delay and Expression of Cancer and Host VEGF, VEGFR2, and Osteopontin in Response to Radiotherapy

AU - Solberg, Timothy D.

AU - Nearman, Jessica

AU - Mullins, John

AU - Li, Sicong

AU - Baranowska-Kortylewicz, Janina

PY - 2008/11/1

Y1 - 2008/11/1

N2 - Purpose: To determine the late effects of radiotherapy (RT) on vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR2), and osteopontin (OPN) expression in cancer and stromal cells. Methods and Materials: LS174T xenografted athymic mice were used as a tumor model. Radiation was delivered in two equivalent fractionation schemes: 5 × 7 Gy and 1 × 20 Gy, the latter at two dose rates. Results: Tumor growth arrest was similar in all treatment groups, with the exception of a better response of small-size tumors in the 5 × 7-Gy group. The host VEGF and OPN levels were directly proportional to the tumor doubling time and were independent of the fractionation scheme. The host and cancer cell VEGFR2 levels in tumor were also directly related to the tumor response to RT. Conclusion: Upregulated VEGFR2 in cancer cells suggest paracrine signaling in the VEGFR2 pathway of cancer cells as the factor contributing to RT failure. The transient activation of the host VEGF/VEGFR2 pathway in tumor supports the model of angiogenic regeneration and suggests that radiation-induced upregulation of VEGF, VEGFR2, and downstream proteins might contribute to RT failure by escalating the rate of vascular repair. Coexpression of host OPN and VEGF, two factors closely associated with angiogenesis, indicate that OPN can serve as a surrogate marker of tumor recovery after RT. Taken together, these results strongly support the notion that to achieve optimal therapeutic outcomes, the scheduling of RT and antiangiogenic therapies will require patient-specific post-treatment monitoring of the VEGF/VEGFR2 pathway and that tumor-associated OPN can serve as an indicator of tumor regrowth.

AB - Purpose: To determine the late effects of radiotherapy (RT) on vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR2), and osteopontin (OPN) expression in cancer and stromal cells. Methods and Materials: LS174T xenografted athymic mice were used as a tumor model. Radiation was delivered in two equivalent fractionation schemes: 5 × 7 Gy and 1 × 20 Gy, the latter at two dose rates. Results: Tumor growth arrest was similar in all treatment groups, with the exception of a better response of small-size tumors in the 5 × 7-Gy group. The host VEGF and OPN levels were directly proportional to the tumor doubling time and were independent of the fractionation scheme. The host and cancer cell VEGFR2 levels in tumor were also directly related to the tumor response to RT. Conclusion: Upregulated VEGFR2 in cancer cells suggest paracrine signaling in the VEGFR2 pathway of cancer cells as the factor contributing to RT failure. The transient activation of the host VEGF/VEGFR2 pathway in tumor supports the model of angiogenic regeneration and suggests that radiation-induced upregulation of VEGF, VEGFR2, and downstream proteins might contribute to RT failure by escalating the rate of vascular repair. Coexpression of host OPN and VEGF, two factors closely associated with angiogenesis, indicate that OPN can serve as a surrogate marker of tumor recovery after RT. Taken together, these results strongly support the notion that to achieve optimal therapeutic outcomes, the scheduling of RT and antiangiogenic therapies will require patient-specific post-treatment monitoring of the VEGF/VEGFR2 pathway and that tumor-associated OPN can serve as an indicator of tumor regrowth.

KW - Osteopontin

KW - Stereotactic body radiotherapy

KW - VEGF

KW - VEGFR2

KW - Vascular endothelial growth factor

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JO - International Journal of Radiation Oncology Biology Physics

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