Recent studies correlate Hedgehog (Hh) signaling with reduced survival rates in triple negative breast cancer (TNBC) patients. Activation of hedgehog signaling in the adjacent mesenchyme has been shown to promote tumor growth and it is a poor prognosis factor for TNBC. We developed a novel tumor-mesenchymal in vitro model of hedgehog signaling in TNBC to evaluate the role of mesenchymal cell sub-populations in the proliferative potential and stem cell markers of breast cancer cells using a custom designed multiwell array. As a source of mesenchymal cell sub-populations we evaluated myofibroblasts, mesenchymal stem cells derived from bone marrow or adipose tissue and tumor cells that undergo epithelial-mesenchymal transition (EMT). Tumor cells were culture with 1 or 2 mesenchymal cell sub-populations in adjacent compartments +/- SHH ligand for 72-96hrs. Active Hh signaling was confirmed by up-regulation of main Hh target genes (e.g. Gli1, Patch1). Paracrine Hh signaling only in bone marrow-derived mesenchymal stem cell and EMT significantly increased proliferation (10-15%) of TNBC and normal breast cancer cell lines. Addition of adipose-derived mesenchymal stem cells or pharmacological Hh inhibitors (Cyclopamine and Gant61) partially abolished tumor growth indicating that other non-canonical signals are involve in paracrine Hh-driven tumors. Cancer stem cell markers were selectively modulated in co-cultures. Our results suggest that paracrine Hh signaling-driven by bone marrow and EMT mesenchymal are potential therapeutic targets to treating TNBC.

Citation Format: Karla P. Ramos, Maribella Domenech. Mesenchymal cell sub-populations selectively modulate paracrine hedgehog signaling in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1334. doi:10.1158/1538-7445.AM2017-1334