Secretion of MCP-1 and other paracrine factors in a novel tumor-bone coculture model

Intact or marrow-depleted neonatal mouse femurs and select murine and human sarcoma or carcinoma cell lines were incubated singly or in coculture in specialized well plates. Viability of the bone and cells was determined by immunohistochemical stains, microscopy and marrow cytopreps. Secretion and mRNA expression of paracrine factors was quantitated by ELISA and real-time RT-PCR.Compartments of the bone were optimally viable for up to 48 h in culture and tumor cells for up to 4 days. Bone was the major contributor of TGF-β and MMP2 whereas both bone and sarcoma cells secreted the chemokine MCP-1 in cocultures. Synergistic interaction between the femur and sarcoma resulted in enhanced MCP-1 secretion and expression in cocultures and was dependent on the presence of the hematopoietic component of the bone as well as other bone cells. In contrast, coculturing with breast carcinoma cells resulted in reduction of TGF-β and MCP-1 secretion from the bone.These studies illustrate the feasibility of this model to examine paracrine interactions between intact bone and tumor cells. Further study of unique regulation of MCP-1 secretion and signaling between these cell types in different types of cancer will be possible using this simulated microenvironment.Cancer is a disease whose outcome is determined by the malignant tumor cells themselves as well as by the microenvironment in which they reside. The initial cellular oncogenic transformation is due to the acquisition or inheritance of genetic mutations which endows these cells with a malignant phenotype. The subsequent successful progression of a tumor also requires favorable tumor-host interactions. Within the tumor microenvironment, it is the non-malignant cells, often termed the 'stroma', which are active and essential components that are recruited and exploited by malignant cells to ensure tumor survival and growth [1]. This is also true during metastasis when invasive malignant cells must colonize a 'foreign' microenviro