CCN3 Impairs Osteoblast and Stimulates Osteoclast Differentiation to Favor Breast Cancer Metastasis to Bone

Abstract

Bone is a preferred site for breast cancer metastasis, causing pain, fractures, spinal cord compressions, and hypercalcemia, all of which can significantly diminish the patient's quality of life. We identified CCN3 as a novel factor that is highly expressed in bone metastatic breast cancer cells from a xenograft mouse model and in bone metastatic lesions from patients with breast cancer. We demonstrate that CCN3 overexpression enhances the ability of weakly bone metastatic breast cancer cells to colonize and grow in the bone without altering their growth in the mammary fat pad. We further demonstrated that human recombinant CCN3 inhibits osteoblast differentiation from primary bone marrow cultures, leading to a higher receptor activator of NF-B ligand (RANKL)/osteoprotegerin (OPG) ratio. In conjunction with its ability to impair osteoblast differentiation, we uncovered a novel role for CCN3 in promoting osteoclast differentiation from RANKL-primed monocyte precursors. CCN3 exerts its proosteoclastogenic effects by promoting calcium oscillations and nuclear factor of activated T cells c1 (NFATc1) nuclear translocation. Together, these results demonstrate that CCN3 regulates the differentiation of bone resident cells to create a resorptive environment that promotes the formation of osteolytic breast cancer metastases. Bone is the preferred site for breast cancer metastasis. 1,2Although patients with bone metastasis display better overall survival relative to patients with visceral metastases, their quality of life can be significantly diminished due to pain, fractures, spinal cord compressions, and hypercalcemia. Given the pivotal role of the osteoclast in bone breakdown associated with osteolytic lesions, bisphosphonates (a class of drugs that inhibit osteoclast-dependent bone resorption) are routinely given to patients with breast cancer bone metastases. 4 However, significant research efforts are now focused on the identification and development of targeted therapeutics to further enhance the management of breast cancer metastasis. 5,6

NOV inhibits proliferation while promoting apoptosis and migration in osteosarcoma cell lines through p38/MAPK and JNK/MAPK pathways

“…Besides participating in the growth and prognosis, NOV also exerted effects on the adhesion, migration and invasion of tumor cells (7). Previous studies indicated that NOV activated pI3K/aKT and NF-κB signaling pathways by combining with αvβ3 integrin receptor, thus promoting the transcription and expression of transfer relevant factors (37).…”

“…The CCN genes encode secreted proteins of 35-48 kDa associated with the extracellular matrix (ECM) and cell membrane, which are involved in the regulation of various cell functions such as proliferation, differentiation, migration, attachment, angiogenesis and tumorigenesis (6). These genes are expressed in all derivatives of the three embryonic sheets and are involved in the development of kidney, nervous system, muscle, bone marrow, cartilage and bone (7).…”

Breast cancer — one term, many entities?

“…This suggested that metastases do not randomly target distant organs, but preferentially arise in those that offer the disseminated cancer cell an appropriate environment in which to grow or that express molecules supporting tumor cell homing. Recent studies demonstrate that the expression of specific molecules, including chemokine receptors as well as claudin-2, CCN3, and tenascin-C, correlate with and/or enhance metastasis to distinct sites (119,(136)(137)(138). The chemokine CXCL12 is expressed in bone marrow, and expression of its cognate receptor CXCR4 on breast tumor cells is correlated with an increased risk of metastasis to bone (139).…”

Breast Cancer Metastases to Bone: Role of the Microenvironment

“…Several signalling pathways in osteoclast precursors have been implicated in these effects, including calcium signalling, NFATc1 activation and MAPKs ERK1/2 and p38 (159,160). Tumour-produced CCN3 was demonstrated to stimulate osteoclast formation from RANKL-primed osteoclast precursors (147). These effects can be relevant to the propensity of cancer cells to metastasize to bone sites undergoing active bone remodelling, and thus containing increased numbers of RANKL-primed osteoclast precursors.…”

“…Moreover, under the influence of breast cancer cells, undifferentiated osteoblasts express higher levels of RANKL and lower OPG, resulting in an increase in osteoblast-mediated osteoclastogenesis (20), an effect that was reversed when osteoblastic cultures were treated with the inhibitors of -secretase -an enzyme implicated in Notch signalling (20,136). One of the mediators of these changes was shown to be the tumour-overexpressed CCN3, that can inhibit osteoblast differentiation and shift the RANKL/OPG ratio to favour osteolysis (147). Another osteoblast-produced osteoclastogenic factor, MCSF, has also been implicated in breast cancer metastases to bone (148).…”