Tehran University of Medical Sciences Basic & Clinical Cancer Research 2228-6527 8 3 2016 11 05 9 16 EN Sanaz Rismanchi Cancer Biology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran Ahad Muhammadnejad Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran Elahe Keyhani Genetics Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran Samad Muhammadnejad Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran Saeid Amanpour Cancer Biology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran 2016 08 09 2016 09 05 Background: For xenograft models of triple-negative breast cancer (TNBC) to be valuable in development of molecularly-targeted drugs, careful characterization is essential to their validation. The present study aimed to validate the TNBC xenograft model with a specific focus on angiogenesis. Methods: Twelve TNBC xenograft tumors and 12 human breast cancer tumors (HTNBC) were included in this study. Both groups were grade III and p53 positive. Nuclear pleomorphism and mitotic count were analyzed by hematoxylin and eosin (H&E) stains respectively. Basal cytokeratin (CK5/6), vimentin, cathepsin-D, Ki-67 (for proliferation), and MVD-CD34 (for angiogenesis) markers were examined by immunohistochemistry (IHC). The association of Microvesseles density (MVD) with Ki-67, nuclear pleomorphism, and mitotic count was assessed in each group separately, and HTNBCs were compared with the xenograft group. Results: The xenograft models showed a significant correlation between angiogenesis (MVD) and cell proliferation (Ki-67), nuclear pleomorphism, and mitotic count (p= 0.0398; p= 0.020; p=0.001, respectively). The HTNBC group also showed a similar trend, except nuclear pleomorphism (p=0.193), which did not correlate with angiogenesis. Comparison between the two groups showed significant changes in cell proliferation (Ki-67 and vimentin). The difference in proliferation rate and vimentin expression between the two groups can be due to biological diversity between human and mice and epithelial-mesenchymal transition (EMT), respectively. Conclusion:  Our results, re-emphasize the significance of angiogenic treatment therapy in patients with TNBC, and further validate the TNBC xenograft model as a valid model for drug discovery and development. https://bccr.tums.ac.ir/index.php/bccrj/article/view/199 https://bccr.tums.ac.ir/index.php/bccrj/article/download/199/02