Abstract 524: Interaction of metastatic breast cancer cells with osteoblasts and osteoclasts in a 3D in-vitro model

Abstract

Abstract Breast cancer frequently metastasizes to bone where it causes osteolytic lesions. Although, the bone osteoclasts, not the cancer cells themselves, appear to be responsible for the bone resorbtion, we have evidence from 3D in vitro cell culture studies (bioreactor) that in the presence of breast cancer cells or their medium, the osteoblasts no longer make the proteins required for bone repair. Furthermore, they produce inflammatory cytokines, which in turn can stimulate osteoclasts. We have developed a bioreactor system that permits continuous growth of bone-accreting osteoblasts (MC3T3-E1) for > 10 months without subculture or perfusion. This results in a mineralizing, multiple-cell-layer tissue that strongly resembles normal bone. We have also shown that, by challenging this osteoblast tissue with human metastatic breast cancer cells (MDA-MB-231GFP), important hallmarks of cancer metastasis including single cell filing of cancer cells, cancer-cell penetration of tissue and colonization can be observed. We hypothesize that addition of osteoclast to this 3D mineralizing osteoblast in the bioreactor would be a relevant in vitro bone surrogate for studying stages of breast-cancer metastasis. In standard tissue culture and in the bioreactor, we have been able to differentiate osteoclasts from hematopoietic progenitor cells isolated from murine bone marrow. The osteoclasts formed by exposure to RANKL and M-CSF were multi-nucleated, TRAP positive cells. The pre-osteoclast cells when introduced onto the osteoblast grown in the bioreactor, differentiated to form multinucleated resorbing osteoclast, also positive for TRAP and actin ring staining. To further improve the bone remodeling aspect, pre-osteoblasts will be re-infused into the system and allowed to ‘re-mineralize’ the matrix resorbed by osteoclasts. Once the system is established, breast cancer cells will be added to examine the three way cell interactions. This 3D in-vitro cell culture system containing both osteoblast and osteoclast will help to further understand the cellular and molecular events that lead to successful breast cancer colonization of bone. Positive outcomes of the work will help clarify the etiology of metastasis but also create a much-needed in vitro tool for study of cancer therapeutics. This work was supported by US Army Medical and Materiel Command Breast Cancer Idea Program (W81XWH-06-1-0432). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 524.