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Effect of antiangiogenic therapy on tumor growth, vasculature and kinase activity in basal- and luminal-like breast cancer xenografts.

ABSTRACT: Several clinical trials have investigated the efficacy of bevacizumab in breast cancer, and even if growth inhibiting effects have been registered when antiangiogenic treatment is given in combination with chemotherapy no gain in overall survival has been observed. One reason for the lack of overall survival benefit might be that appropriate criteria for selection of patients likely to respond to antiangiogenic therapy in combination with chemotherapy, are not available. To determine factors of importance for antiangiogenic treatment response and/or resistance, two representative human basal- and luminal-like breast cancer xenografts were treated with bevacizumab and doxorubicin alone or in combination. In vivo growth inhibition, microvessel density (MVD) and proliferating tumor vessels (pMVD = proliferative microvessel density) were analysed, while kinase activity was determined using the PamChip Tyrosine kinase microarray system. Results showed that both doxorubicin and bevacizumab inhibited basal-like tumor growth significantly, but with a superior effect when given in combination. In contrast, doxorubicin inhibited luminal-like tumor growth most effectively, and with no additional benefit of adding antiangiogenic therapy. In agreement with the growth inhibition data, vascular characterization verified a more pronounced effect of the antiangiogenic treatment in the basal-like compared to the luminal-like tumors, demonstrating total inhibition of pMVD and a significant reduction in MVD at early time points (three days after treatment) and sustained inhibitory effects until the end of the experiment (day 18). In contrast, luminal-like tumors only showed significant effect on the vasculature at day 10 in the tumors having received both doxorubicin and bevacizumab. Kinase activity profiling in both tumor models demonstrated that the most effective treatment in vivo was accompanied with increased phosphorylation of kinase substrates of growth control and angiogenesis, like EGFR, VEGFR2 and PLC?1. This may be a result of regulatory feedback mechanisms contributing to treatment resistance, and may suggest response markers of value for the prediction of antiangiogenic treatment efficacy.

SUBMITTER: Lindholm EM

PROVIDER: S-EPMC5528356 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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Effect of antiangiogenic therapy on tumor growth, vasculature and kinase activity in basal- and luminal-like breast cancer xenografts.

Lindholm Evita M EM Kristian Alexandr A Nalwoga Hawa H Krüger Kristi K Nygård Ståle S Akslen Lars A LA Mælandsmo Gunhild M GM Engebraaten Olav O

Molecular oncology 20120331 4

Several clinical trials have investigated the efficacy of bevacizumab in breast cancer, and even if growth inhibiting effects have been registered when antiangiogenic treatment is given in combination with chemotherapy no gain in overall survival has been observed. One reason for the lack of overall survival benefit might be that appropriate criteria for selection of patients likely to respond to antiangiogenic therapy in combination with chemotherapy, are not available. To determine factors of ...[more]

PMID: 22521242

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Project description:With the advent of potent second-line anti-androgen therapy, we and others have observed an increased incidence of androgen receptor (AR)-null small cell or neuroendocrine prostate cancer (SCNPC) in metastatic castration-resistant prostate cancer (mCRPC). Additionally, we have detected upregulated expression of MET and RET transcripts in SCNPC metastases relative to adenocarcinoma. Our study was designed to determine the effect of cabozantinib, a multi-targeted tyrosine kinase inhibitor that inhibits MET, RET and VEGFR2, on SCNPC patient-derived xenografts (PDX) in vivo. Surveillance of SU2C and University of Washington rapid autopsy mCRPC cohorts through RNA-Seq revealed that increased MET expression significantly correlated with loss of AR expression and activity. In vitro treatment of SCNPC PDX cells with AMG 337 had no impact on cell viability in LuCaP 93 (MET+/RET+) and LuCaP 173.1 (MET-/RET-), whereas cabozantinib decreased cell viability in LuCaP 93, but not in LuCaP 173.1. Notably, tumor volume was significantly decreased (p<0.001) with cabozantinib treatment in SCID mice bearing LuCaP 93 and LuCaP 173.1 tumors. Tissue analysis indicated that tumor cell proliferation was not inhibited by cabozantinib, but that cabozantinib decreased microvessel density (CD31) in LuCaP 93 (p<0.001) and LuCaP 173.1 (p<0.01) tumors. RNA-Seq and gene set enrichment analysis determined that hypoxia and glycolysis pathways were increased in cabozantinib treated tumors relative to control tumors. Thus, cabozantinib inhibited tumor growth in MET+/RET+ LuCaP 93 and MET-/RET- LuCaP 173.1 tumors in vivo and this activity was independent of MET or RET expression in LuCaP 173.1. Our data suggest that the most likely mechanism of tumor growth suppression is through disruption of the stromal architecture and cabozantinib may represent a potential therapy for patients with metastatic disease in tumor phenotypes that have a significant dependence on the tumor vasculature for survival and proliferation.

Dataset Information

Effect of antiangiogenic therapy on tumor growth, vasculature and kinase activity in basal- and luminal-like breast cancer xenografts.

Publications

Effect of antiangiogenic therapy on tumor growth, vasculature and kinase activity in basal- and luminal-like breast cancer xenografts.

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