Changes in Cytokines of the Bone Microenvironment during Breast Cancer Metastasis

It is commonly accepted that cancer cells interact with host cells to create a microenvironment favoring malignant colonization. The complex bone microenvironment produces an ever changing array of cytokines and growth factors. In this study, we examined levels of MCP-1, IL-6, KC, MIP-2, VEGF, MIG, and eotaxin in femurs of athymic nude mice inoculated via intracardiac injection with MDA-MB-231GFP human metastatic breast cancer cells, MDA-MB-231BRMS1GFP, a metastasis suppressed variant, or PBS. Animals were euthanized (day 3, 11, 19, 27 after injection) to examine femoral cytokine levels at various stages of cancer cell colonization. The epiphysis contained significantly more cytokines than the diaphysis except for MIG which was similar throughout the bone. Variation among femurs was evident within all groups. By day 27, MCP-1, MIG, VEGF and eotaxin levels were significantly greater in femurs of cancer cell-inoculated mice. These pro-osteoclastic and angiogenic cytokines may manipulate the bone microenvironment to enhance cancer cell colonization

Breast cancer metastasis to the bone: mechanisms of bone loss

Breast cancer frequently metastasizes to the skeleton, interrupting the normal bone remodeling process and causing bone degradation. Osteolytic lesions are the end result of osteoclast activity; however, osteoclast differentiation and activation are mediated by osteoblast production of RANKL (receptor activator for NFκB ligand) and several osteoclastogenic cytokines. Osteoblasts themselves are negatively affected by cancer cells as evidenced by an increase in apoptosis and a decrease in proteins required for new bone formation. Thus, bone loss is due to both increased activation of osteoclasts and suppression of osteoblasts. This review summarizes the current understanding of the osteolytic mechanisms of bone metastases, including a discussion of current therapies

Dormancy and growth of metastatic breast cancer cells in a bone-like microenvironment

Abstract Breast cancer can reoccur, often as bone metastasis, many years if not decades after the primary tumor has been treated. The factors that stimulate dormant metastases to grow are not known, but bone metastases are often associated with skeletal trauma. We used a dormancy model of MDA-MB-231BRMS1, a metastasis-suppressed human breast cancer cell line, co-cultured with MC3T3-E1 osteoblasts in a long term, three dimensional culture system to test the hypothesis that bone remodeling cytokines could stimulate dormant cells to grow. The cancer cells attached to the matrix produced by MC3T3-E1 osteoblasts but grew slowly or not at all until the addition of bone remodeling cytokines, TNFa and IL-b. Stimulation of cell proliferation by these cytokines was suppressed with indomethacin, an inhibitor of cyclooxygenase and of prostaglandin production, or a prostaglandin E2 (PGE2) receptor antagonist. Addition of PGE2 directly to the cultures also stimulated cell proliferation. MCF-7, non-metastatic breast cancer cells, remained dormant when co-cultured with normal human osteoblast and fibroblast growth factor. Similar to the MDA-MB-231BRMS1 cells, MCF-7 proliferation increased in response to TNFa and IL-b. These findings suggest that changes in the bone microenvironment due to inflammatory cytokines associated with bone repair or excess turnover may trigger the occurrence of latent bone metastasis

3D printing of poly(epsilon-caprolactone)/poly(D,L-lactide-co-glycolide)/hydroxyapatite composite constructs for bone tissue engineering

WOS: 000440179300005Three-dimensional (3D) printing technology is a promising method for bone tissue engineering applications. For enhanced bone regeneration, it is important to have printable ink materials with appealing properties such as construct interconnectivity, mechanical strength, controlled degradation rates, and the presence of bioactive materials. In this respect, we develop a composite ink composed of polycaprolactone (PCL), poly(D,L-lactide-co-glycolide) (PLGA), and hydroxyapatite particles (HAps) and 3D print it into porous constructs. In vitro study revealed that composite constructs had higher mechanical properties, surface roughness, quicker degradation profile, and cellular behaviors compared to PCL counterparts. Furthermore, in vivo results showed that 3D-printed composite constructs had a positive influence on bone regeneration due to the presence of newly formed mineralized bone tissue and blood vessel formation. Therefore, 3D printable ink made of PCL/PLGA/HAp can be a highly useful material for 3D printing of bone tissue constructs.National Science FoundationNational Science Foundation (NSF) [1600118]; Osteology Foundation [15-042]; International Postdoctoral Research Scholarship Program of the Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [BIDEP 2219]This work was partially supported by the National Science Foundation Award No. 1600118 and Osteology Foundation Award No. 15-042. The authors are thankful to Dr. Wu Yang for his assistance with the histology study. Dr. Veli Ozbolat acknowledges the support from the International Postdoctoral Research Scholarship Program (BIDEP 2219) of the Scientific and Technological Research Council of Turkey (TUBITAK). The authors are also thankful to Materials Research Institute at the Pennsylvania State University in supporting the X-ray scattering experiment. The authors also thank Dr. Abhishek Shetty from Anton-Paar USA, Inc. for his assistance with the rheology experiments. The authors confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome

Selenium modifies the osteoblast inflammatory stress response to bone metastatic breast cancer

Breast cancer frequently metastasizes to the skeleton resulting in bone degradation due to osteoclast activation. Metastases also downregulate differentiation and the bone-rebuilding function of osteoblasts. Moreover, cancer cells trigger osteoblast inflammatory stress responses. Pro-inflammatory mediators such as interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), expressed by osteoblasts (MC3T3-E1) stimulated with human breast cancer cell (MDA-MB-231) conditioned medium, are pivotal to osteoclast activation and metastasis. Given that these genes are regulated by nuclear factor-κB (NF-κB), a redox-sensitive transcription factor, we hypothesized that selenium (Se) could abrogate the inflammatory response to metastatic breast cancer cells by modulating NF-κB. Caffeic acid phenethyl ester and parthenolide inhibited NF-κB activation, as seen by gel shift assays and immunoblotting for p65 in nuclear fractions, as well as decreased production of IL-6 and MCP-1. Supplementation of MC3T3-E1 with methylseleninic acid (MSA) (0.5 μM to 4 μM) reduced the activation of NF-κB leading to a decrease in IL-6, MCP-1, COX-2 and iNOS in response to MDA-MB-231 conditioned medium. Addition of MSA to osteoblasts for as little as 15 min suppressed activation of NF-κB suggesting that short-lived active metabolites might be involved. However, brief exposure to MSA also brought about an increase in selenoprotein glutathione peroxidase 1. In summary, our data indicate that the osteoblast response to metastatic breast cancer cells is regulated by NF-κB activation, which can be effectively suppressed by MSA either through short-lived active metabolites and/or selenoproteins. Thus, Se supplementation may prevent the osteoblast inflammatory response or dampen the vicious cycle established when breast cancer cells, osteoblasts and osteoclasts interact