cancer

Stromal-Initiated Changes in the Bone Promote Metastatic Niche Development

Authors

Xianmin Luo, Yujie Fu, Andrew J. Loza, Bhavna Murali, Kathleen M. Leahy, Megan K. Ruhland, Margery Gang, Xinming Su, Ali Zamani, Yu Shi, Kory J. Lavine, David M. Ornitz, Katherine N. Weilbaecher, Fanxin Long, Deborah V. Novack, Roberta Faccio, Gregory D. Longmore, Sheila A. Stewart

Abstract

More than 85% of advanced breast cancer patients suffer from metastatic bone lesions, yet the mechanisms that facilitate these metastases remain poorly understood. Recent studies suggest that tumor-derived factors initiate changes within the tumor microenvironment to facilitate metastasis. However, whether stromal-initiated changes are sufficient to drive increased metastasis in the bone remains an open question. Thus, we developed a model to induce reactive senescent osteoblasts and found that they increased breast cancer colonization of the bone. Analysis of senescent osteoblasts revealed that they failed to mineralize bone matrix and increased local osteoclastogenesis, the latter process being driven by the senescence-associated secretory phenotype factor, IL-6. Neutralization of IL-6 was sufficient to limit senescence-induced osteoclastogenesis and tumor cell localization to bone, thereby reducing tumor burden. Together, these data suggest that a reactive stromal compartment can condition the niche, in the absence of tumor-derived signals, to facilitate metastatic tumor growth in the bone.

Link to Article

http://dx.doi.org/10.1016/j.celrep.2015.12.016

Gut-derived serotonin induced by depression promotes breast cancer bone metastasis through the RUNX2/PTHrP/RANKL pathway in mice

Authors

Jian‑Chun Zong, Xing Wang, Xiang Zhou, Chen Wang, Liang Chen, Liang‑Jun Yin, Bai‑Cheng He, Zhong‑Liang Deng

Abstract

Breast cancer metastasizes to the bone in a majority of patients with advanced disease resulting in bone destruction. The underlying mechanisms are complex, and both processes are controlled by an interaction between locally and systemically derived signals. Clinically, breast cancer patients with depression have a higher risk of bone metastasis, yet the etiology and mechanisms are yet to be elucidated. MDA‑MB‑231 breast cancer cells were used to establish a bone metastasis model by using intracardiac injection in nude mice. Chronic mild stress (CMS) was chosen as a model of depression in mice before and after inoculation of the cells. Knockdown of the RUNX‑2 gene was performed by transfection of the cells with shRNA silencing vectors against human RUNX‑2. A co‑culture system was used to test the effect of the MDA‑MB‑231 cells on osteoclasts and osteoblasts. RT‑PCR and western blotting were used to test gene and protein expression, respectively. We confirmed that depression induced bone metastasis by promoting osteoclast activity while inhibiting osteoblast differentiation. Free serotonin led to an increase in the expression of RUNX2 in breast cancer cells (MDA‑MB‑231), which directly inhibited osteoblast differentiation and stimulated osteoclast differentiation by the PTHrP/RANKL pathway, which caused bone destruction and formed osteolytic bone lesions. Additionally, the interaction between depression and breast cancer cells was interrupted by LP533401 or RUNX2 knockdown. In conclusion, depression promotes breast cancer bone metastasis partly through increasing levels of gut‑derived serotonin. Activation of RUNX2 in breast cancer cells by circulating serotonin appears to dissociate coupling between osteoblasts and osteoclasts, suggesting that the suppression of gut‑derived serotonin decreases the rate of breast cancer bone metastasis induced by depression.

Link to Article

http://www.spandidos-publications.com/10.3892/or.2015.4430

Excess TGF-β mediates muscle weakness associated with bone metastases in mice

Authors

David L Waning, Khalid S Mohammad, Steven Reiken, Wenjun Xie, Daniel C Andersson, Sutha John, Antonella Chiechi, Laura E Wright, Alisa Umanskaya, Maria Niewolna, Trupti Trivedi, Sahba Charkhzarrin, Pooja Khatiwada, Anetta Wronska, Ashley Haynes, Maria Serena Benassi, Frank A Witzmann, Gehua Zhen, Xiao Wang, Xu Cao, G David Roodman, Andrew R Marks & Theresa A Guise

Abstract

Cancer-associated muscle weakness is a poorly understood phenomenon, and there is no effective treatment. Here we find that seven different mouse models of human osteolytic bone metastases—representing breast, lung and prostate cancers, as well as multiple myeloma—exhibited impaired muscle function, implicating a role for the tumor-bone microenvironment in cancer-associated muscle weakness. We found that transforming growth factor (TGF)-β, released from the bone surface as a result of metastasis-induced bone destruction, upregulated NADPH oxidase 4 (Nox4), resulting in elevated oxidization of skeletal muscle proteins, including the ryanodine receptor and calcium (Ca2+) release channel (RyR1). The oxidized RyR1 channels leaked Ca2+, resulting in lower intracellular signaling, which is required for proper muscle contraction. We found that inhibiting RyR1 leakage, TGF-β signaling, TGF-β release from bone or Nox4 activity improved muscle function in mice with MDA-MB-231 bone metastases. Humans with breast- or lung cancer–associated bone metastases also had oxidized skeletal muscle RyR1 that is not seen in normal muscle. Similarly, skeletal muscle weakness, increased Nox4 binding to RyR1 and oxidation of RyR1 were present in a mouse model of Camurati-Engelmann disease, a nonmalignant metabolic bone disorder associated with increased TGF-β activity. Thus, pathological TGF-β release from bone contributes to muscle weakness by decreasing Ca2+-induced muscle force production.

Link to Article

http://dx.doi.org/10.1038/nm.3961

A Histomorphometric Analysis of Radiation Damage in an Isogenic Murine Model of Distraction Osteogenesis

Authors

Alexander R. Zheutlin, BS, Sagar S. Deshpande, BS, Noah S. Nelson, BS, Yekaterina Polyatskaya, MD, Jose J. Rodriguez, MD, Alexis Donneys, MD, MS, Steven R. Buchman, MD

Abstract

Purpose The devastation radiation therapy (XRT) causes to endogenous tissue in head and neck cancer (HNC) patients can be a prohibitive obstacle in reconstruction of the mandible, demanding a better understanding of XRT-induced damage and options for reconstruction. Our study investigates the cellular damage caused by radiation in an isogenic murine model of mandibular distraction osteogenesis (DO). We posit that radiation will result in reduced osteocytes, with elevated empty lacunae and immature osteoid.

Methods Twenty Lewis rats were randomly assigned to two groups: DO (n=10) and XRT/DO (n=10). Both groups underwent an osteotomy and mandibular DO across a 5.1 mm gap. XRT was administered to the XRT/DO group at a fractionated, human equivalent dose of 35 Gy prior to surgery. Animals were sacrificed on postoperative day 40 and mandibles were harvested and sectioned for histological analysis.

Results Bone that underwent radiation revealed a significantly decreased osteocyte count and complementary increase in empty lacunae when compared to non-XRT bone (p=0.019, p=0.000). Additionally, XRT bone demonstrated increased immature osteoid and decreased mature woven bone when compared to non-radiated bone (p=0.001 and p=0.003, respectively). Furthermore, analysis of the ratio of immature osteoid to woven bone volume exhibited a significant increase in the XRT bone, further revealing the devastating damage brought by XRT (p=0.001).

Conclusion These results clearly demonstrate the cellular diminution that occurs as a result of radiation. This foundational study provides the groundwork upon which to investigate cellular therapies in an immunoprivileged model of mandibular DO.

Link To Article

http://dx.doi.org/10.1016/j.joms.2015.08.002

The TGF-β Signaling Regulator PMEPA1 Suppresses Prostate Cancer Metastases to Bone

Authors

Pierrick G.J. Fournier, Patricia Juárez, Guanglong Jiang, Gregory A. Clines, Maria Niewolna, Hun Soo Kim, Holly W. Walton, Xiang Hong Peng, Yunlong Liu, Khalid S. Mohammad, Clark D. Wells, John M. Chirgwin, Theresa A. Guise

Abstract

Transforming growth factor-β (TGF-β) regulates the expression of genes supporting breast cancer cells in bone, but little is known about prostate cancer bone metastases and TGF-β. Our study reveals that the TGFBR1 inhibitor SD208 effectively reduces prostate cancer bone metastases. TGF-β upregulates in prostate cancer cells a set of genes associated with cancer aggressiveness and bone metastases, and the most upregulated gene was PMEPA1. In patients, PMEPA1 expression decreased in metastatic prostate cancer and low Pmepa1 correlated with decreased metastasis-free survival. Only membrane-anchored isoforms of PMEPA1 interacted with R-SMADs and ubiquitin ligases, blocking TGF-β signaling independently of the proteasome. Interrupting this negative feedback loop by PMEPA1 knockdown increased prometastatic gene expression and bone metastases in a mouse prostate cancer model.

Link To Article

http://dx.doi.org/10.1016/j.ccell.2015.04.009

Single-Limb Irradiation Induces Local and Systemic Bone Loss in a Murine Model

Authors

Laura E. Wright Ph.D., Jeroen T. Buijs Ph.D., Hun-Soo Kim M.D., Laura E. Coats M.D., Anne M. Scheidler M.D., Sutha K. John M.S., Yun She B.A., Sreemala Murthy M.S., Ning Ma M.D., Helen J. Chin- Sinex B.S., Teresita M. Bellido Ph.D., Ted A. Bateman Ph.D., Marc S. Mendonca Ph.D., Khalid S. Mohammad M.D., Ph.D. and Theresa A. Guise M.D.

Abstract

Increased fracture risk is commonly reported in cancer patients receiving radiotherapy, particularly at sites within the field of treatment. The direct and systemic effects of ionizing radiation on bone at a therapeutic dose are not well characterized in clinically relevant animal models. Using twenty-week male C57Bl/6 mice, effects of irradiation (right hindlimb; 2 Gy) on bone volume and microarchitecture were evaluated prospectively by microcomputed tomography and histomorphometry and compared to contralateral-shielded bone (left hindlimb) and non-irradiated control bone. One-week post-irradiation, trabecular bone volume declined in irradiated tibiae (-22%; p < 0.0001) and femora (-14%; p = 0.0586) and microarchitectural parameters were compromised. Trabecular bone volume declined in contralateral tibiae (-17%; p = 0.003), and no loss was detected at the femur. Osteoclast number, apoptotic osteocyte number and marrow adiposity were increased in irradiated bone relative to contralateral and non-irradiated bone, while osteoblast number was unchanged. Despite no change in osteoblast number one-week post-irradiation, dynamic bone formation indices revealed a reduction in mineralized bone surface and a concomitant increase in unmineralized osteoid surface area in irradiated bone relative to contralateral and non-irradiated control bone. Further, dose- and time-dependent calvarial culture and in vitro assays confirmed that calvarial osteoblasts and osteoblast-like MC3T3 cells were relatively radioresistant, while calvarial osteocyte and osteocyte-like MLO-Y4 cell apoptosis was induced as early as 48h post-irradiation (4 Gy). In osteoclastogenesis assays, radiation exposure (8 Gy) stimulated murine macrophage RAW264.7 cell differentiation and co-culture of irradiated RAW264.7 cells with MLO-Y4 or murine bone marrow cells enhanced this effect. These studies highlight the multi-faceted nature of radiation-induced bone loss by demonstrating direct and systemic effects on bone and its many cell types using clinically relevant doses and have important implications for bone health in patients treated with radiation therapy.

Link To Article

http://dx.doi.org/10.1002/jbmr.2458