VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatment
<p>Abstract</p> <p>Background</p> <p>Targeting tumor vasculature is a strategy with great promise in the treatment of many cancers. However, anti-angiogenic reagents that target VEGF/VEGFR2 signaling have met with variable results clinically. Among the possible reasons...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2010-12-01
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| Series: | BMC Cancer |
| Online Access: | http://www.biomedcentral.com/1471-2407/10/683 |
| _version_ | 1811249717898641408 |
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| author | Skowronski Karolina Minhas Kanwal Lacombe Kristen Adamcic Una Patten Steven G Coomber Brenda L |
| author_facet | Skowronski Karolina Minhas Kanwal Lacombe Kristen Adamcic Una Patten Steven G Coomber Brenda L |
| author_sort | Skowronski Karolina |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Targeting tumor vasculature is a strategy with great promise in the treatment of many cancers. However, anti-angiogenic reagents that target VEGF/VEGFR2 signaling have met with variable results clinically. Among the possible reasons for this may be heterogeneous expression of the target protein.</p> <p>Methods</p> <p>Double immunofluorescent staining was performed on formalin-fixed paraffin embedded sections of treated and control SW480 (colorectal) and WM239 (melanoma) xenografts, and tissue microarrays of human colorectal carcinoma and melanoma. Xenografts were developed using RAG1<sup>-/- </sup>mice by injection with WM239 or SW480 cells and mice were treated with 20 mg/kg/day of cyclophosphamide in their drinking water for up to 18 days. Treated and control tissues were characterized by double immunofluorescence using the mural cell marker α-SMA and CD31, while the ratio of desmin/CD31 was also determined by western blot. Hypoxia in treated and control tissues were quantified using both western blotting for HIF-1α and immunohistochemistry of CA-IX.</p> <p>Results</p> <p>VEGFR2 is heterogeneously expressed in tumor vasculature in both malignant melanoma and colorectal carcinoma. We observed a significant decrease in microvascular density (MVD) in response to low dose metronomic cyclophosphamide chemotherapy in both malignant melanoma (with higher proportion VEGFR2 positive blood vessels; 93%) and colorectal carcinoma (with lower proportion VEGFR2 positive blood vessels; 60%) xenografts. This reduction in MVD occurred in the absence of a significant anti-tumor effect. We also observed less hypoxia in treated melanoma xenografts, despite successful anti-angiogenic blockade, but no change in hypoxia of colorectal xenografts, suggesting that decreases in tumor hypoxia reflect a complex relationship with vascular density. Based on α-SMA staining and the ratio of desmin to CD31 expression as markers of tumor blood vessel functionality, we found evidence for increased stabilization of colorectal microvessels, but no such change in melanoma vessels.</p> <p>Conclusions</p> <p>Overall, our study suggests that while heterogeneous expression of VEGFR2 is a feature of human tumors, it may not affect response to low dose metronomic cyclophosphamide treatment and possibly other anti-angiogenic approaches. It remains to be seen whether this heterogeneity is partly responsible for the variable clinical success seen to date with targeted anti-VEGFR2 therapy.</p> |
| first_indexed | 2024-04-12T15:51:26Z |
| format | Article |
| id | doaj.art-191b8d0280394b3b837ed058276f594e |
| institution | Directory Open Access Journal |
| issn | 1471-2407 |
| language | English |
| last_indexed | 2024-04-12T15:51:26Z |
| publishDate | 2010-12-01 |
| publisher | BMC |
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| series | BMC Cancer |
| spelling | doaj.art-191b8d0280394b3b837ed058276f594e2022-12-22T03:26:29ZengBMCBMC Cancer1471-24072010-12-0110168310.1186/1471-2407-10-683VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatmentSkowronski KarolinaMinhas KanwalLacombe KristenAdamcic UnaPatten Steven GCoomber Brenda L<p>Abstract</p> <p>Background</p> <p>Targeting tumor vasculature is a strategy with great promise in the treatment of many cancers. However, anti-angiogenic reagents that target VEGF/VEGFR2 signaling have met with variable results clinically. Among the possible reasons for this may be heterogeneous expression of the target protein.</p> <p>Methods</p> <p>Double immunofluorescent staining was performed on formalin-fixed paraffin embedded sections of treated and control SW480 (colorectal) and WM239 (melanoma) xenografts, and tissue microarrays of human colorectal carcinoma and melanoma. Xenografts were developed using RAG1<sup>-/- </sup>mice by injection with WM239 or SW480 cells and mice were treated with 20 mg/kg/day of cyclophosphamide in their drinking water for up to 18 days. Treated and control tissues were characterized by double immunofluorescence using the mural cell marker α-SMA and CD31, while the ratio of desmin/CD31 was also determined by western blot. Hypoxia in treated and control tissues were quantified using both western blotting for HIF-1α and immunohistochemistry of CA-IX.</p> <p>Results</p> <p>VEGFR2 is heterogeneously expressed in tumor vasculature in both malignant melanoma and colorectal carcinoma. We observed a significant decrease in microvascular density (MVD) in response to low dose metronomic cyclophosphamide chemotherapy in both malignant melanoma (with higher proportion VEGFR2 positive blood vessels; 93%) and colorectal carcinoma (with lower proportion VEGFR2 positive blood vessels; 60%) xenografts. This reduction in MVD occurred in the absence of a significant anti-tumor effect. We also observed less hypoxia in treated melanoma xenografts, despite successful anti-angiogenic blockade, but no change in hypoxia of colorectal xenografts, suggesting that decreases in tumor hypoxia reflect a complex relationship with vascular density. Based on α-SMA staining and the ratio of desmin to CD31 expression as markers of tumor blood vessel functionality, we found evidence for increased stabilization of colorectal microvessels, but no such change in melanoma vessels.</p> <p>Conclusions</p> <p>Overall, our study suggests that while heterogeneous expression of VEGFR2 is a feature of human tumors, it may not affect response to low dose metronomic cyclophosphamide treatment and possibly other anti-angiogenic approaches. It remains to be seen whether this heterogeneity is partly responsible for the variable clinical success seen to date with targeted anti-VEGFR2 therapy.</p>http://www.biomedcentral.com/1471-2407/10/683 |
| spellingShingle | Skowronski Karolina Minhas Kanwal Lacombe Kristen Adamcic Una Patten Steven G Coomber Brenda L VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatment BMC Cancer |
| title | VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatment |
| title_full | VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatment |
| title_fullStr | VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatment |
| title_full_unstemmed | VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatment |
| title_short | VEGFR2 heterogeneity and response to anti-angiogenic low dose metronomic cyclophosphamide treatment |
| title_sort | vegfr2 heterogeneity and response to anti angiogenic low dose metronomic cyclophosphamide treatment |
| url | http://www.biomedcentral.com/1471-2407/10/683 |
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