Abstract 2311: Two complementary populations of human adipose tissue CD34+ progenitors promote breast cancer angiogenesis, growth, and metastases.
Authors: Orecchioni Stefania , Gregato Giuliana , Martin-Padura Ines , Mancuso Patrizia , Calleri Angelica , Corsini Chiara , Martella Stefano , Petit Jean-Yves , Bertolini Francesco 
Published: August 2014

We recently reported that human white adipose tissue (WAT) progenitors promote breast cancer growth and metastases in preclinical models (Martin-Padura et al, 2012). Here we report that two populations of human WAT progenitors cooperate in breast cancer angiogenesis, growth and metastatic progression. Sorting, electron microscopy, culture and in vivo studies defined human WAT CD45-CD34+CD31+CD13-CCRL2+ endothelial progenitors (EPCs) as small, undifferentiated cells overexpressing endothelial-restricted genes (VE-Cadherin, Claudin 5; Tie-2, ICAM-2, Dll4, etc) and able to generate in vitro and in vivo mature endothelial cells. A second population of purified WAT CD45-CD34+CD31-CD13+CD140b+ pericyte progenitors (PPCs) was found to overexpress perivascular genes (Endosialin, Adam12, PDGF receptors, TGFbeta, CD44, RUNX1, etc). In vivo and in vitro, CD34+ PPCs generated differentiated CD34- pericytes and adipocytes. In co-culture, WAT EPCs and PPCs - together - induced in ductal breast cancer cell lines an overexpression of EMT genes (SNAIL2, ZEB1, MAP1B, etc). Similarly, WAT EPCs and PPCs induced - together - an increase in breast cancer cell migration towards chemoattractants. When only EPCs or only PPCs were added to breast cancer cell cultures, their EMT- and migration-induction effects were significantly lower than those observed when both EPCs and PPCs were co-cultured together. In vivo, human WAT EPCs and PPCs increased breast cancer angiogenesis, growth and metastases in several orthotopic models. When only EPCs or only PPCs were injected, their effects on breast cancer growth and metastases were significantly reduced in comparison to the effects observed when EPCs and PPCs were injected together. Z-stack showed that functional cancer blood vessels with a lumen were made of human cells only when EPCs and PPCs were co-injected together. To understand WAT EPCs and PPCs migration potential, we measured WAT EPCs and PPCs in the blood of patients before and after different stem cell mobilization procedures. WAT-EPCs (always &lt;1/mL before mobilization) increased to 2-800/mL after G-CSF administration. The addition of chemotherapy and/or CXCR4 inhibitors did not increase WAT-EPC mobilization. WAT-PPCs were always &lt;1/mL before mobilization. G-CSF administration was associated to a minimal mobilization of these cells (10-70/mL), but only in 3 out of 15 patients. Again, the addition of chemotherapy and/or CXCR4 inhibitors to G-CSF did not increase PPC mobilization. WAT-EPCs, but not WAT-PPCs, were found in large numbers in human lymph nodes (LNs). Our studies indicate that human WAT EPCs and PPCs are able to migrate to LNs (EPCs) and blood and to promote breast cancer angiogenesis, EMT, growth and metastases through complementary mechanisms. We are currently investigating several candidate inhibitors of WAT EPCs and PPCs cooperation in vitro and in vivo.

Citation Format: Stefania Orecchioni, Giuliana Gregato, Ines Martin-Padura, Patrizia Mancuso, Angelica Calleri, Chiara Corsini, Stefano Martella, Jean-Yves Petit, Francesco Bertolini. Two complementary populations of human adipose tissue CD34+ progenitors promote breast cancer angiogenesis, growth, and metastases. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2311. doi:10.1158/1538-7445.AM2013-2311