W B Carter1, M D Ward. 1. Department of Surgery, Eastern Virginia Medical School, Norfolk, VA, USA.
Abstract
BACKGROUND: HER2 overexpression is a marker of aggressive breast cancer. Tumors that overexpress HER2 induce endothelial cell retraction and endothelial destabilization. Because angiopoietin-2 (Ang-2) also destabilizes microvessels, we postulated that HER2 signaling upregulates Ang-2 as a mechanism of angioinvasion. METHODS: We tested human breast cancers and breast cancer cell lines for coexpression of HER2 and Ang-2 with Northern blot, reverse transcriptase-polymerase chain reaction, and enzyme-linked immunosorbent assay. Further, we manipulated HER2 signaling with 100 ng/mL MAbHu HER2 (Herceptin; Genentech, San Francisco, Calif) and Heregulin beta1 (100 ng/mL; R&D Systems, Inc, Minneapolis, Minn) to test for HER2 regulation of Ang-2 production. RESULTS: Three of 4 breast cancer cell lines expressed HER2 protein and Ang-2 mRNA. HER cells, a stably transfected cell line that overexpresses HER2 6-fold, showed a 430% increase in Ang-2 mRNA compared to parental MCF-7 cells. Heregulin beta1 stimulation of HER2 signaling in MCF-7 cells increased Ang-2 by 20% (P <.05). HER2 signaling blockade with 100 ng/mL Herceptin reduced Ang-2 mRNA 90% (P <.001). Five of 11 cancers expressed both HER2 and Ang-2; 2 cancers expressed only Ang-2. CONCLUSIONS: We conclude that human breast cancers express Ang-2. HER2 signaling appears to regulate Ang-2 expression, although other signaling pathways may also regulate Ang-2. Ang-2 may be a therapeutic target in these cancers and may define which patients would benefit from Herceptin therapy.
BACKGROUND:HER2 overexpression is a marker of aggressive breast cancer. Tumors that overexpress HER2 induce endothelial cell retraction and endothelial destabilization. Because angiopoietin-2 (Ang-2) also destabilizes microvessels, we postulated that HER2 signaling upregulates Ang-2 as a mechanism of angioinvasion. METHODS: We tested humanbreast cancers and breast cancer cell lines for coexpression of HER2 and Ang-2 with Northern blot, reverse transcriptase-polymerase chain reaction, and enzyme-linked immunosorbent assay. Further, we manipulated HER2 signaling with 100 ng/mL MAbHu HER2 (Herceptin; Genentech, San Francisco, Calif) and Heregulin beta1 (100 ng/mL; R&D Systems, Inc, Minneapolis, Minn) to test for HER2 regulation of Ang-2 production. RESULTS: Three of 4 breast cancer cell lines expressed HER2 protein and Ang-2 mRNA. HER cells, a stably transfected cell line that overexpresses HER2 6-fold, showed a 430% increase in Ang-2 mRNA compared to parental MCF-7 cells. Heregulin beta1 stimulation of HER2 signaling in MCF-7 cells increased Ang-2 by 20% (P <.05). HER2 signaling blockade with 100 ng/mL Herceptin reduced Ang-2 mRNA 90% (P <.001). Five of 11 cancers expressed both HER2 and Ang-2; 2 cancers expressed only Ang-2. CONCLUSIONS: We conclude that humanbreast cancers express Ang-2. HER2 signaling appears to regulate Ang-2 expression, although other signaling pathways may also regulate Ang-2. Ang-2 may be a therapeutic target in these cancers and may define which patients would benefit from Herceptin therapy.
Authors: Raju K Pillai; Jean R Lopategui; Deepti Dhall; Maha Guindi; Thomas Slavin; Catherine E Lofton-Day; Scott D Patterson Journal: Adv Anat Pathol Date: 2016-03 Impact factor: 3.875