Homing of cancer cells to the bone

From molecular mechanisms of prostate cancer to translational applications: based on multi-omics fusion analysis and intelligent medicine

Prostate cancer is the most common cancer in men worldwide and has a high mortality rate. The complex and heterogeneous development of prostate cancer has become a core obstacle in the treatment of prostate cancer. Simultaneously, the issues of overtreatment in early-stage diagnosis, oligometastasis and dormant tumor recognition, as well as personalized drug utilization, are also specific concerns that require attention in the clinical management of prostate cancer. Some typical genetic mutations have been proved to be associated with prostate cancer's initiation and progression. However, single-omic studies usually are not able to explain the causal relationship between molecular alterations and clinical phenotypes. Exploration from a systems genetics perspective is also lacking in this field, that is, the impact of gene network, the environmental factors, and even lifestyle behaviors on disease progression. At the meantime, current trend emphasizes the utilization of artificial intelligence (AI) and machine learning techniques to process extensive multidimensional data, including multi-omics. These technologies unveil the potential patterns, correlations, and insights related to diseases, thereby aiding the interpretable clinical decision making and applications, namely intelligent medicine. Therefore, there is a pressing need to integrate multidimensional data for identification of molecular subtypes, prediction of cancer progression and aggressiveness, along with perosonalized treatment performing. In this review, we systematically elaborated the landscape from molecular mechanism discovery of prostate cancer to clinical translational applications. We discussed the molecular profiles and clinical manifestations of prostate cancer heterogeneity, the identification of different states of prostate cancer, as well as corresponding precision medicine practices. Taking multi-omics fusion, systems genetics, and intelligence medicine as the main perspectives, the current research results and knowledge-driven research path of prostate cancer were summarized.

LSD1 modulates the bone metastasis of breast cancer cells through hnRNPA2B1-mediated sorting of exosomal miRNAs

Bone metastasis is a key contributor to morbidity and mortality of breast cancer patients. We have previously shown that exosomal miRNAs derived from LSD1 knockdown (KD) breast cancer cells inhibit osteoblast differentiation and promote osteoclast differentiation. However, how LSD1 regulates exosomal miRNAs and whether miRNAs promote bone metastasis through the formation of pre-metastatic niches remains unclear. In vivo experiments demonstrates that exosomes derived from LSD1 KD breast cancer cells significantly promoted bone metastasis. To explore the mechanism underlying the effect of LSD1 on exosomes in breast cancer cells, exosomal and cellular miRNAs from control, LSD1 KD, and rescue cells were sequenced. Interestingly, approximately 80% of LSD1-associated miRNAs were downregulated in exosomes from LSD1 KD cells. The consensus sequence UAGGGC, was identified in many miRNAs downregulated in LSD1 KD exosomes. We found that hnRNPA2B1 regulated the exosomal sorting of miR-6881-3p and some other miRNAs. LSD1 deficiency reduced hnRNPA2B1 expression in breast cancer cells by decreasing the level of H3K9me2 demethylation in the promoter region of the hnRNPA2B1 gene. Our study revealed that LSD1 plays a crucial role in the regulation of exosomal sorting of miRNA.

Single-cell sequencing analysis reveals the relationship between tumor microenvironment cells and oxidative stress in breast cancer bone metastases

Bone metastasis (BM) is one of the main manifestations of advanced breast cancer (BC), causing complications such as pathological fractures, which seriously affects the quality of life of patients and even leads to death. In our study, a global single-cell landscape of the tumor microenvironment was constructed using single cell RNA sequencing data from BM. BC cells were found to be reduced in the BM, while mesenchymal stem cells (MSCs), Fibroblasts and other cells were significantly more abundant in the BM. The subpopulations of these cells were further identified, and the pathways, developmental trajectories and transcriptional regulation of different subpopulations were discussed. The results suggest that with the development of BM, BC cells were vulnerable to oxidative damage, showing a high level of oxidative stress, which played a key role in cell apoptosis. Fibroblasts were obviously involved in the biological processes (BPs) related to ossification and bone remodeling, and play an important role in tumor cell inoculation to bone marrow and growth. MSC subpopulations were significantly enriched in a number of BPs associated with bone growth and development and oxidative stress and may serve as key components of BC cells homing and adhesion to the ecological niche of BM. In conclusion, our research results describe the appearance of tumor microenvironment cell subpopulations in breast cancer patients, reveal the important role of some cells in the balance of BM bone remodeling and the imbalance of BM development, and provide potential therapeutic targets for BM.

CD44 in Bone Metastasis Development: A Key Player in the Fate Decisions of the Invading Cells?

A participant in key developmental processes, the adhesion glycoprotein CD44 is also expressed in several types of malignancies and can promote metastasis. In addition, the expression of CD44 isoforms in different types of cancer such as prostate and breast cancers may facilitate bone metastases by enhancing tumorigenicity, osteomimicry, cell migration, homing to bone, and anchorage within the bone specialized domains. Moreover, there is evidence that the CD44-ICD fragments in breast cancer cells may promote the cells' osteolytic nature. Yet the mechanisms by which CD44 and its downstream effectors promote the establishment of these cells within the bone are not fully elucidated. In this review, we summarize the current data on the roles played by CD44 in cancer progression and bone metastasis and the possible effects of its interaction with the different components of the bone marrow milieu.

Study of Hemato-morphological Features in Neuroblastoma Infiltrating Marrow

Objective Neuroblastoma typically affects children within the first 5 years of life and accounts for 10% of all pediatric malignancies. Neuroblastoma at onset may manifest as a localized or metastatic illness. The aim of this study was to identify hematomorphological features in neuroblastoma infiltrating marrow as well as to ascertain the prevalence of bone marrow infiltration in neuroblastoma.

Materials and Methods This retrospective study included newly diagnosed 79 cases of neuroblastoma, which were referred for bone marrow examination for the staging of the disease. Medical records were retrieved to acquire hematomorphological findings of peripheral blood and bone marrow smears. Statistical Package for Social Sciences, IBM Inc., USA, version 21.0 was used to analyze the data.

Results The interquartile age range of neuroblastoma cases was 24.0 to 72.0 months (median = 48 months) with a male to female ratio of 2.7:1. Also, 55.6% (44/79) of cases in the study population showed evidence of marrow infiltration. The bone marrow infiltration was significantly linked to thrombocytopenia (p = 0.043) and nucleated red blood cells (p = 0.003) in peripheral blood. The bone marrow smears of cases with infiltration showed a significant shift to the left in the myeloid series (p = 0.001) and an increased number of erythroid cells (p = 0.001).

Conclusion For neuroblastoma patients, a diligent, exhaustive search for infiltrating cells in bone marrow is advised if thrombocytopenia or nucleated red blood cells are identified on a peripheral blood smear and bone marrow smears showed myeloid left shift with an increased number of erythroid cells.

Cancer cell foraging to explain bone-specific metastatic progression

Metastatic cancer is lethal and patients who suffer bone metastases fare especially poorly. Bone-specific metastatic progression in prostate and breast cancers is a highly observed example of organ-specific metastasis, or organotropism. Though research has delineated the sequential steps of the metastatic cascade, the determinants of bone-specific metastasis have remained elusive for decades. Applying fundamental ecological principles to cancer biology models of metastasis provides novel insights into metastatic organotropism. We use critical concepts from foraging theory and movement ecology to propose that observed bone-specific metastasis is the result of habitat selection by foraging cancer cells. Furthermore, we posit that cancer cells can only perform habitat selection if and when they employ a reversible motile foraging strategy. Only a very small percentage of cells in a primary tumor harbor this ability. Therefore, our habitat selection model emphasizes the importance of identifying the rare subset of cancer cells that might exhibit habitat selection, ergo achieve bone-specific metastatic colonization.

Hypoxia-activated neuropeptide Y/Y5 receptor/RhoA pathway triggers chromosomal instability and bone metastasis in Ewing sarcoma

Adverse prognosis in Ewing sarcoma (ES) is associated with the presence of metastases, particularly in bone, tumor hypoxia and chromosomal instability (CIN). Yet, a mechanistic link between these factors remains unknown. We demonstrate that in ES, tumor hypoxia selectively exacerbates bone metastasis. This process is triggered by hypoxia-induced stimulation of the neuropeptide Y (NPY)/Y5 receptor (Y5R) pathway, which leads to RhoA over-activation and cytokinesis failure. These mitotic defects result in the formation of polyploid ES cells, the progeny of which exhibit high CIN, an ability to invade and colonize bone, and a resistance to chemotherapy. Blocking Y5R in hypoxic ES tumors prevents polyploidization and bone metastasis. Our findings provide evidence for the role of the hypoxia-inducible NPY/Y5R/RhoA axis in promoting genomic changes and subsequent osseous dissemination in ES, and suggest that targeting this pathway may prevent CIN and disease progression in ES and other cancers rich in NPY and Y5R.

Ewing sarcoma tumour cells frequently metastasize to the bone but the molecular mechanisms governing this process are not well understood. Here, the authors show that neuropeptide Y/Y5 receptor pathway is activated in the hypoxic tumour microenvironment, which results in cytokinesis defects and chromosomal instability, leading to bone invasion.

Bone Metastases: From Mechanisms to Treatment

OBJECTIVES

Bone metastases are of high clinical relevance because they are a frequent complication of most types of common cancers, such as breast and prostate. The metastatic process is complex, requiring the completion of several different steps to allow successful dissemination and homing. In addition, preparation of the metastatic niche changes the constant cycle of bone matrix formation and degradation, leading to the clinical phenotypes of lytic and sclerotic lesions. We review our current knowledge on this topic and briefly explain the current treatment landscape of bone metastasis.

DATA SOURCES

These include PubMed, international guidelines, and clinician experience.

CONCLUSION

Bone metastases remain a clinical challenge that negatively impacts patients prognosis and quality of life. A comprehensive understanding of the complex molecular mechanisms that results in bone metastasis is the basis for successful treatment of affected patients. The disruption of bone matrix metabolism is already recognized as the prerequisite for metastasis formation, but many open questions remain that need to be addressed in future research to establish individually tailored treatment approaches.

IMPLICATIONS FOR NURSING PRACTICE

Patient-centered therapy of bone metastases requires suitable pharmacological options, and importantly a holistic approach in care delivery across the multidisciplinary team. Nurses provide the cornerstone of the multidisciplinary team and provide the closest and the most frequent contact to the patient and their families to provide timely intervention. Nurses require a basic understanding of the complex physiology of metastasis to inform practice.

Delivery strategies in treatments of leukemia

Leukemia is a hematological malignancy associated with the uncontrolled proliferation of mutant progenitors, suppressing the production of normal blood cells. Current treatments, including chemotherapy, radiotherapy, and immunotherapy, still lead to unsatisfactory results with a 5 year survival rate of only 30-50%. The poor prognosis is related to both disease relapse and treatment-associated toxicity. Delivery strategies can improve the in vivo pharmacokinetics of drugs, navigating the therapeutics to target cells or the tumor microenvironment and reversing drug resistance, which maximizes tumor elimination and alleviates systematic adverse effects. This review discusses available FDA-approved anti-leukemia drugs and therapies with a focus on the advances in the development of anti-leukemia drug delivery systems. Additionally, challenges in clinical translation of the delivery strategies and future research opportunities in leukemia treatment are also included.

Isolation of CD31+ Bone Marrow Endothelial Cells (BMECs) from Mice

In the bone marrow microenvironment, endothelial cells (ECs) play a pivotal role in regulating the production of both growth and inhibiting factors. They are held together by adherence molecules that interact with hematopoietic progenitor cells. The study of ECs in the hematopoietic stem cell niche is limited due to the lack of efficient protocols for isolation. In this protocol, we developed a two-step approach to extract bone marrow endothelial cells (BMECs) to unlock the challenges researchers face in understanding the function of the endothelial vascular niche in in-vitro studies.

Bone marrow/bone pre-metastatic niche for breast cancer cells colonization: The role of mesenchymal stromal cells

Breast cancer is one of the most common oncological pathologies in women worldwide. While its early diagnosis has considerably improved, about 70 % of advanced patients develop bone metastases with a high mortality rate. Several authors demonstrated that primary breast cancer cells prepare their future metastatic niche -known as the pre-metastatic niche- to turn it into an "optimal soil" for colonization. The role of the different cellular components of the bone marrow/bone niche in bone metastasis has been well described. However, studying the changes that occur in this microenvironment before tumor cells arrival has become a novel research field. Therefore, the purpose of this review is to describe the current knowledge about the modulation of the normal bone marrow/bone niche by the primary breast tumor, in particular, highlighting the role of mesenchymal stem/stromal cells in transforming this soil into a pre-metastatic niche for breast cancer cells colonization.

Extracellular Matrix Components Regulate Bone Sialoprotein Expression in MDA-MB-231 Breast Cancer Cells

Bone sialoprotein (BSP) has become a target in breast cancer research as it is associated with tumor progression and metastasis. The mechanisms underlying the regulation of BSP expression have been largely elusive. Given that BSP is involved in the homing of cancer cells in bone metastatic niches, we addressed regulatory effects of proteolytic cleavage and extracellular matrix components on BSP expression and distribution in cell culture models. Therefore, MDA-MB-231 human breast cancer cells were kept in 2D and 3D spheroid cultures and exposed to basement membrane extract in the presence or absence of matrix metalloproteinase 9 or the non-polar protease, dispase. Confocal imaging of immunofluorescence samples stained with different antibodies against human BSP demonstrated a strong inducing effect of basement membrane extract on anti-BSP immunofluorescence. Similarly, protease incubation led to acute upregulation of anti-BSP immunofluorescence signals, which was blocked by cycloheximide, suggesting de novo formation of BSP. In summary, our data show that extracellular matrix components play an important function in regulating BSP expression and hint at mechanisms for the formation of bone-associated metastasis in breast cancer that might involve local control of BSP levels by extracellular matrix degradation and release of growth factors.

How to Target Spinal Metastasis in Experimental Research: An Overview of Currently Used Experimental Mouse Models and Future Prospects

The spine is one of the organs that is most affected by metastasis in cancer patients. Since the control of primary tumor is continuously improving, treatment of metastases is becoming one of the major challenges to prevent cancer-related death. Due to the anatomical proximity to the spinal cord, local spread of metastasis can directly cause neurological deficits, severely limiting the patient’s quality of life. To investigate the underlying mechanisms and to develop new therapies, preclinical models are required which represent the complexity of the multistep cascade of metastasis. Current research of metastasis focuses on the formation of the premetastatic niche, tumor cell dormancy and the influence and regulating function of the immune system. To unveil whether these influence the organotropism to the spine, spinal models are irreplaceable. Mouse models are one of the most suitable models in oncologic research. Therefore, this review provides an overview of currently used mouse models of spinal metastasis. Furthermore, it discusses technical aspects clarifying to what extend these models can picture key steps of the metastatic process. Finally, it addresses proposals to develop better mouse models in the future and could serve as both basis and stimulus for researchers and clinicians working in this field.

A 3D printed in vitro bone model for the assessment of molecular and cellular cues in metastatic neuroblastoma

Metastasis is a complex and multifactorial process highly dependent on the interaction between disseminated tumor cells and the pre-metastatic niche. The metastatic sites detected in the bone of patients affected by neuroblastoma (NB), a malignancy of the developing sympathetic nervous system, are particularly aggressive. To improve our current knowledge of metastatic tumor cell biology and improve treatment success, appropriate in vitro and in vivo models that more closely resemble the native metastatic niche are needed. In this study, the impact of the geometry of synthetic β-tricalcium-phosphate (β-TCP) structures on the interaction of NB tumor cells with the stromal component has been examined. The tumor microenvironment is dynamically shaped by the stroma, which sustains the growth of NB cells inside the metastatic niche. The 3D growth conditions are a determining factor for the cell proliferation rate in β-TCP. With respect to planar counterparts, channeled 3D β-TCP structures stimulate more interleukin-6 and Fibronectin production and define Connexin 43 distribution inside the cells. Together, these results highlight how the biomechanical properties of the 3D microenvironment enable tumor cells to form spheroid-shaped arrangements. This, in turn, facilitates their pro-migratory and pro-invasive patterns and mimics the in vivo situation by translating realistic mechanobiological cues to the metastatic NB.

Perfusion bioreactor enabled fluid-derived shear stress conditions for novel bone metastatic prostate cancer testbed

Critical understanding of the complex metastatic cascade of prostate cancer is necessary for the development of a therapeutic interventions for treating metastatic prostate cancer. Increasing evidence supports the synergistic role of biochemical and biophysical cues in cancer progression at metastases. The biochemical factors such as cytokines have been extensively studied in relation to prostate cancer progression to the bone; however, the role of shear stress-induced by interstitial fluid around bone extracellular matrix has not been fully explored as a driving factor for prostate cancer metastasis. Shear stress governs various cellular processes, including cell proliferation and migration. Thus, it is essential to understand the impact of fluid-derived shear stress on the aggressiveness of prostate cancer at the metastatic stage. Here, we report development of a three-dimensional (3D) in-vitro dynamic cell culture system to recapitulate the microenvironment of prostate cancer bone metastasis, to understand the cause of modulation in cell response under fluid-derived shear stress. We observed an increased human mesenchymal stem cells (hMSCs) proliferation and differentiation rate under dynamic culture. We observed that hMSCs under static culture form cell agglutinates, whereas under dynamic culture, hMSCs exhibited a directional alignment with broad and flattened morphology. Next, we observed increased expression of mesenchymal to epithelial transition (MET) biomarkers in bone metastasized prostate cancer models as well as large changes in cellular and tumoroid morphologies with shear stress. Evaluation of cell adhesion proteins indicated that the altered cancer cell morphologies resulted from the constant force pulling due to increased E-Cadherin and phosphorylated Focal adhesion kinase (FAK) proteins under shear stress. Collectively, we have successfully developed a 3D in-vitro dynamic model to recapitulate the behavior of bone metastatic prostate cancer under dynamic conditions.

Cryo-shocked cancer cells for targeted drug delivery and vaccination

Live cells have been vastly engineered into drug delivery vehicles to leverage their targeting capability and cargo release behavior. Here, we describe a simple method to obtain therapeutics-containing "dead cells" by shocking live cancer cells in liquid nitrogen to eliminate pathogenicity while preserving their major structure and chemotaxis toward the lesion site. In an acute myeloid leukemia (AML) mouse model, we demonstrated that the liquid nitrogen-treated AML cells (LNT cells) can augment targeted delivery of doxorubicin (DOX) toward the bone marrow. Moreover, LNT cells serve as a cancer vaccine and promote antitumor immune responses that prolong the survival of tumor-bearing mice. Preimmunization with LNT cells along with an adjuvant also protected healthy mice from AML cell challenge.

Bone metastases

Bone is the most frequent site for metastasis for many cancers, notably for tumours originating in the breast and the prostate. Tumour cells can escape from the primary tumour site and colonize the bone microenvironment. Within the bone, these disseminated tumour cells, as well as those arising in the context of multiple myeloma, may assume a state of dormancy, remaining quiescent for years before resuming proliferation and causing overt metastasis, which causes bone destruction via activation of osteoclast-mediated osteolysis. This structural damage can lead to considerable morbidity, including pain, fractures and impaired quality of life. Although treatment of bone metastases and myeloma bone disease is rarely curative, disease control is often possible for many years through the use of systemic anticancer treatments on a background of multidisciplinary supportive care. This care should include bone-targeted agents to inhibit tumour-associated osteolysis and prevent skeletal morbidity as well as use of appropriate local treatments such as radiation therapy, orthopaedic surgery and specialist palliative care to minimize the impact of metastatic bone disease on physical functioning. In this Primer, we provide an overview of the clinical features, the pathophysiology and the specific treatment approaches to prevent and treat bone metastases from solid tumours as well as myeloma bone disease.

Bone Invasive Properties of Oral Squamous Cell Carcinoma and its Interactions with Alveolar Bone Cells: An In Vitro Study

BACKGROUND

Co-culture of cancer cells with alveolar bone cells could modulate bone invasion and destructions. However, the mechanisms of interaction between oral squamous cell carcinoma (OSCC) and bone cells remain unclear.

OBJECTIVE

The aim of this study is to analyse the direct and indirect effects of OSCC cells in the stimulation of osteolytic activity and bone invasion.

METHODS

Direct co-culture was achieved by culturing OSCC (TCA8113) with a primary alveolar bone cell line. In the indirect co-culture, the supernatant of TCA8113 cells was collected to culture the alveolar bone cells. To assess the bone invasion properties, in vitro assays were performed.

RESULTS

The proliferation of co-cultured cancer cells was significantly (p<0.05) higher in comparison to the monolayer control cells. However, the proliferation rates were not significantly different between direct and indirect co-cultured cells with indirect co-cultured cells proliferated slightly more than the direct co-cultured cells. Invasion and migration capacities of co-cultured OSCC and alveolar bone cells enhanced significantly (p<0.05) when compared to that of control monolayer counterparts. Most importantly, we noted that OSCC cells directly co-cultured with alveolar bone cells stimulated pronounced bone collagen destruction. In addition, stem cells and epithelialmesenchymal transition markers have shown significant changes in their expression in co-cultured cells.

CONCLUSION

In conclusion, the findings of this study highlight the importance of the interaction of alveolar bone cells and OSCC cells in co-culture setting in the pathogenesis of bone invasion. This may help in the development of potential future biotherapies for bone invasion in OSCC.

PAK1 inhibitor IPA-3 mitigates metastatic prostate cancer-induced bone remodeling

Metastatic prostate cancer (PCa) has high mortality and a poor 5-year survival rate primarily due to the lack of effective treatments. Bone is the primary site of PCa metastasis in humans and the development of reliable therapeutic options for bone metastatic PCa will make a huge impact in reducing the mortality among these patients. Although P21 activated kinases (PAKs) have been studied in the past for their role in cancer, the efficacy of targeting PAKs to treat lung and bone metastatic PCa has not been tested yet. In the current study, we report that targeting PAK1 using IPA-3, an allosteric inhibitor of PAK1 kinase activity, significantly inhibits the murine metastatic PCa (RM1) cell proliferation and motility in vitro, and metastasis to the lungs in vivo. More importantly, we demonstrate for the first time that treatment with IPA-3 can blunt metastatic PCa-induced bone remodeling in vivo as analyzed by the 3-dimensional microcomputer tomography analysis. Our study has identified IPA-3 as a potential drug to treat bone metastatic PCa.

Harnessing the versatile role of OPG in bone oncology: counterbalancing RANKL and TRAIL signaling and beyond

More than 2 decades ago, the discovery of osteoprotegerin (OPG) as inhibitor of the receptor of activator of nuclear factor Kb (RANK) ligand (RANKL) revolutionized our understanding of bone biology and oncology. Besides acting as decoy receptor for RANKL, OPG acts as decoy receptor for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). OPG, RANKL, and TRAIL are ubiquitously expressed, stimulating per se pivotal signaling cascades implicated in cancer. In the context of cancer cell-bone cell interactions, cancer cells skew the OPG/RANKL/RANK (RANKL cognate receptor) balance towards bone destruction and tumor growth through favoring the RANKL/RANK interface, circumventing OPG. Numerous preclinical and clinical studies demonstrate the dual role of OPG in cancer: antitumor and tumor-promoting. OPG potentially conveys an antitumor signal through inhibiting the tumor-promoting RANKL signaling-both the osteoclast-dependent and the osteoclast-independent-and the tumor-promoting TRAIL signaling. On the other hand, the presumed tumor-promoting functions of OPG are: (i) abrogation of TRAIL-induced apoptosis of cancer cells; (ii) abrogation of RANKL-induced antitumor immunity; and (iii) stimulation of oncogenic and prometastatic signaling cascades downstream of the interaction of OPG with diverse proteins. The present review dissects the role of OPG in bone oncology. It presents the available preclinical and clinical data sustaining the dual role of OPG in cancer and focuses on the imbalanced RANKL/RANK/OPG interplay in the landmark "vicious cycle" of skeletal metastatic disease, osteosarcoma, and multiple myeloma. Finally, current challenges and future perspectives in exploiting OPG signaling in bone oncology therapeutics are discussed.

Tissue-engineered 3D models for elucidating primary and metastatic bone cancer progression

Malignant bone tumors are aggressive neoplasms which arise from bone tissue or as a result of metastasis. The most prevalent types of cancer, such as breast, prostate, and lung cancer, all preferentially metastasize to bone, yet the role of the bone niche in promoting cancer progression remains poorly understood. Tissue engineering has the potential to bridge this knowledge gap by providing 3D in vitro systems that can be specifically designed to mimic key properties of the bone niche in a more physiologically relevant context than standard 2D culture. Elucidating the crucial components of the bone niche that recruit metastatic cells, support tumor growth, and promote cancer-induced destruction of bone tissue would support efforts for preventing and treating these devastating malignancies. In this review, we summarize recent efforts focused on developing in vitro 3D models of primary bone cancer and bone metastasis using tissue engineering approaches. Such 3D in vitro models can enable the identification of effective therapeutic targets and facilitate high-throughput drug screening to effectively treat bone cancers. STATEMENT OF SIGNIFICANCE: Biomaterials-based 3D culture have been traditionally used for tissue regeneration. Recent research harnessed biomaterials to create 3D in vitro cancer models, with demonstrated advantages over conventional 2D culture in recapitulating tumor progression and drug response in vivo. However, previous work has been largely limited to modeling soft tissue cancer, such as breast cancer and brain cancer. Unlike soft tissues, bone is characterized with high stiffness and mineral content. Primary bone cancer affects mostly children with poor treatment outcomes, and bone is the most common site of cancer metastasis. Here we summarize emerging efforts on engineering 3D bone cancer models using tissue engineering approaches, and future directions needed to further advance this relatively new research area.

[The mechanism of anti-RANKL antibody in the treatment of metabolic bone diseases including osteoporosis - possible applications of anti-RANKL antibody to the treatment of cancer patients]

Discovery of RANKL (receptor activator of NF-κB ligand) gave a great impact on identification of the mechanisms regulating osteoclast differentiation and function, establishment of research field bridging bone and mineral research and immunology (osteoimmunology), and development of a fully human anti-RANKL monoclonal neutralizing antibody (denosumab). Denosumab has been clinically available for treatment of osteoporosis and cancer-induced bone diseases in the US, Europe and many countries including Japan. Denosumab is a so-called blockbuster of which sales amount was 3.9 billion US dollars in 2017. Because RANKL is the absolute factor for osteoclast differentiation, anti-RANKL antibody is very effective and its application is good news for many patients. Recent topics are the identification of importance of RANKL on osteoblasts in regulation of osteogenesis and the demonstration of RANKL-RANK (the receptor of RANKL) dual signaling in coupling between bone resorption and bone formation. RANKL reverse signaling that we had hypothesized was demonstrated at last. In this review I describe the mechanism of anti-RANKL antibody in the treatment of metabolic bone diseases including osteoporosis. I also suggest possible applications of anti-RANKL antibody to the treatment of cancer patients.

Reversing the Tumor Target: Establishment of a Tumor Trap

Despite the tremendous progress made in the field of cancer therapy in recent years, certain solid tumors still cannot be successfully treated. Alongside classical treatments in the form of chemotherapy and/or radiotherapy, targeted treatments such as immunotherapy that cause fewer side effects emerge as new options in the clinics. However, these alternative treatments may not be useful for treating all types of cancers, especially for killing infiltrative and circulating tumor cells (CTCs). Recent advances pursue the trapping of these cancer cells within a confined area to facilitate their removal for therapeutic and diagnostic purposes. A good understanding of the mechanisms behind tumor cell migration may drive the design of traps that mimic natural tumor niches and guide the movement of the cancer cells. To bring this trapping idea into reality, strong efforts are being made to create structured materials that imitate myelinated fibers, blood vessels, or pre-metastatic niches and incorporate chemical cues such as chemoattractants or adhesive proteins. In this review, the different strategies used (or could be used) to trap tumor cells are described, and relevant examples of their performance are analyzed.

Targeting the tumour stroma to improve cancer therapy

Cancers are not composed merely of cancer cells alone; instead, they are complex 'ecosystems' comprising many different cell types and noncellular factors. The tumour stroma is a critical component of the tumour microenvironment, where it has crucial roles in tumour initiation, progression, and metastasis. Most anticancer therapies target cancer cells specifically, but the tumour stroma can promote the resistance of cancer cells to such therapies, eventually resulting in fatal disease. Therefore, novel treatment strategies should combine anticancer and antistromal agents. Herein, we provide an overview of the advances in understanding the complex cancer cell-tumour stroma interactions and discuss how this knowledge can result in more effective therapeutic strategies, which might ultimately improve patient outcomes.

Engineering osteoblastic metastases to delineate the adaptive response of androgen-deprived prostate cancer in the bone metastatic microenvironment

While stromal interactions are essential in cancer adaptation to hormonal therapies, the effects of bone stroma and androgen deprivation on cancer progression in bone are poorly understood. Here, we tissue-engineered and validated an in vitro microtissue model of osteoblastic bone metastases, and used it to study the effects of androgen deprivation in this microenvironment. The model was established by culturing primary human osteoprogenitor cells on melt electrowritten polymer scaffolds, leading to a mineralized osteoblast-derived microtissue containing, in a 3D setting, viable osteoblastic cells, osteocytic cells, and appropriate expression of osteoblast/osteocyte-derived mRNA and proteins, and mineral content. Direct co-culture of androgen receptor-dependent/independent cell lines (LNCaP, C4-2B, and PC3) led cancer cells to display functional and molecular features as observed in vivo. Co-cultured cancer cells showed increased affinity to the microtissues, as a function of their bone metastatic potential. Co-cultures led to alkaline phosphatase and collagen-I upregulation and sclerostin downregulation, consistent with the clinical marker profile of osteoblastic bone metastases. LNCaP showed a significant adaptive response under androgen deprivation in the microtissues, with the notable appearance of neuroendocrine transdifferentiation features and increased expression of related markers (dopa decarboxylase, enolase 2). Androgen deprivation affected the biology of the metastatic microenvironment with stronger upregulation of androgen receptor, alkaline phosphatase, and dopa decarboxylase, as seen in the transition towards resistance. The unique microtissues engineered here represent a substantial asset to determine the involvement of the human bone microenvironment in prostate cancer progression and response to a therapeutic context in this microenvironment.

Vinculin Force Sensor Detects Tumor-Osteocyte Interactions

This study utilized a Förster resonance energy transfer (FRET)-based molecular tension sensor and live cell imaging to evaluate the effect of osteocytes, a mechanosensitive bone cell, on the migratory behavior of tumor cells. Two cell lines derived from MDA-MB-231 breast cancer cells were transfected with the vinculin tension sensor to quantitatively evaluate the force in focal adhesions of the tumor cell. Tumor cells treated with MLO-A5 osteocyte-conditioned media (CM) decreased the tensile forces in their focal adhesions and decreased their migratory potential. Tumor cells treated with media derived from MLO-A5 cells exposed to fluid flow-driven shear stress (FFCM) increased the tensile forces and increased migratory potential. Focal adhesion tension in tumor cells was also affected by distance from MLO-A5 cells when the two cells were co-cultured, where tumor cells close to MLO-A5 cells exhibited lower tension and decreased cell motility. Overall, this study demonstrates that focal adhesion tension is involved in altered migratory potential of tumor cells, and tumor-osteocyte interactions decrease the tension and motility of tumor cells.

Seeking for Correlative Genes and Signaling Pathways With Bone Metastasis From Breast Cancer by Integrated Analysis

Background: Bone metastasis frequently occurs in advanced breast cancer patients, and it is one of major causes of breast cancer associated mortality. The aim of the current study is to identify potential genes and related signaling pathways in the pathophysiology of breast cancer bone metastasis.

Methods: Three mRNA expression datasets for breast cancer bone metastasis were obtained from Gene Expression Omnibus (GEO) dataset. The differentially expressed genes (DEGs) were obtained. Functional analyses, protein-protein interaction (PPI) network, and transcription factors (TFs)-target genes network was constructed. Real-time PCR using clinical specimens was conducted to justify the results from integrated analysis.

Results: A 749 DEGs were obtained. Osteoclast differentiation and rheumatoid arthritis were two significantly enriched signaling pathways for DEGs in the bone metastasis of breast cancer. SMAD7 (degree = 10), TGFBR2 (degree = 9), VIM (degree = 8), FOS (degree = 8), PDGFRB (degree = 7), COL5A1 (degree = 6), ARRB2 (degree = 6), and ITGAV (degree = 6) were high degree genes in the PPI network. ETS1 (degree = 12), SPI1 (degree = 12), FOS (degree = 10), FLI1 (degree = 5), KLF4 (degree = 4), JUNB (degree = 4), NR3C1 (degree = 4) were high degree genes in the TFs-target genes network. Validated by QRT-PCR, the expression levels of IBSP, MMP9, MMP13, TNFAIP6, CD200, DHRS3, ASS1, RIPK4, VIM, and PROM1 were roughly consistent with our integrated analysis. Except PROM1, the other genes had a diagnose value for breast cancer bone metastasis.

Conclusions: The identified DEGs and signaling pathways may make contribution for understanding the pathological mechanism of bone metastasis from breast cancer.

Prostate-specific markers to identify rare prostate cancer cells in liquid biopsies

Despite improvements in early detection and advances in treatment, patients with prostate cancer continue to die from their disease. Minimal residual disease after primary definitive treatment can lead to relapse and distant metastases, and increasing evidence suggests that circulating tumour cells (CTCs) and bone marrow-derived disseminated tumour cells (BM-DTCs) can offer clinically relevant biological insights into prostate cancer dissemination and metastasis. Using epithelial markers to accurately detect CTCs and BM-DTCs is associated with difficulties, and prostate-specific markers are needed for the detection of these cells using rare cell assays. Putative prostate-specific markers have been identified, and an optimized strategy for staining rare cancer cells from liquid biopsies using these markers is required. The ideal prostate-specific marker will be expressed on every CTC or BM-DTC throughout disease progression (giving high sensitivity) and will not be expressed on non-prostate-cancer cells in the sample (giving high specificity). Some markers might not be specific enough to the prostate to be used as individual markers of prostate cancer cells, whereas others could be truly prostate-specific and would make ideal markers for use in rare cell assays. The goal of future studies is to use sensitive and specific prostate markers to consistently and reliably identify rare cancer cells.

Real-Time and 3D Quantification of Cancer Cell Dynamics: Exploiting a Bioengineered Human Bone Metastatic Microtissue

The study of dynamic processes in the bone metastatic compartment has been challenged by the restrictive access and limited live imaging capabilities that in vivo bone models provide. In this protocol, we show the use of a human bone metastatic bioengineered microtissue for the quantitative investigation of cancer cells in an in vitro bone-like microenvironment. Using live cell epifluorescence microscopy, traditional- and spinning disc-confocal laser scanning microscopy, we demonstrate how to obtain multidimensional real-time data of fluorescently labeled cancer cells in the metastatic microenvironment. Using 4D imaging data processing software such as ImageJ and Imaris, we show how to transform qualitative images and videos into quantitative data of cancer cell attachment, morphology, proliferation, and migration in vitro in the human bone metastatic microtissue.

177Lu-DOTA-HYNIC-Lys(Nal)-Urea-Glu: Biokinetics, Dosimetry, and Evaluation in Patients with Advanced Prostate Cancer

SPECT/CT images in patients have demonstrated the ability of [99mTc]Tc-EDDA/HYNIC-Lys(Nal)-Urea-Glu ([99mTc]Tc-iPSMA) to detect tumors and metastases of prostate cancer. Considering that theranostics combines the potential of therapeutic and diagnostic radionuclides in the same molecular probe, the aim of this research was to estimate the biokinetics and dosimetry of 177Lu-DOTA-HYNIC-Lys(Nal)-Urea-Glu (177Lu-iPSMA) in healthy subjects and analyze the response in patients receiving 177Lu-iPSMA therapeutic doses. 177Lu-iPSMA was obtained from lyophilized formulations with radiochemical purities >98%. Whole-body images from five healthy subjects were acquired at 20 min, 6, 24, 48, and 120 h after 177Lu-iPSMA administration (185 MBq). The image sequence was used to extrapolate the 177Lu-iPSMA time-activity curves of each organ to adjust the biokinetic model and calculate the total number of disintegrations (N) that occurred in the source regions. N data were the input for the OLINDA/EXM code to calculate internal radiation doses. Ten patients (median age: 68 y; range 58-86 y) received from 1 to 4 cycles of 177Lu-iPSMA (3.7 or 7.4 GBq) every 8-10 weeks. Response was evaluated using the 68Ga-PSMA-ligand-PET/CT or 99mTc-iPSMA-SPECT/CT diagnostic images and serum PSA levels before and after 177Lu-iPSMA treatment. The blood activity showed a half-life value of 1.1 h for the fast component (T 1/2 α = ln2/0.614), 9.2 h for the first slow component (T 1/2 β = ln2/0.075), and 79.6 h for the second slow component (T 1/2 γ = ln2/0.008). The average absorbed doses were 0.23, 0.28, 0.88, and 1.17 Gy/GBq for the spleen, liver, kidney, and salivary glands. A total of 18 cycles were performed in 10 patients. A PSA decrease and some reduction of the radiotracer uptake (SUV) in tumor lesions occurred in 60% and 70% of the patients, respectively. 177Lu-iPSMA obtained from kit formulations showed high tumor uptake with good response rates in patients. The results obtained in this study warrant further clinical studies to establish the optimal number of treatment cycles and for evaluating the effect of this therapeutic agent on survival of patients.

Dynamic Collision Behavior Between Osteoblasts and Tumor Cells Regulates the Disordered Arrangement of Collagen Fiber/Apatite Crystals in Metastasized Bone

Bone metastasis is one of the most intractable bone diseases; it is accompanied with a severe mechanical dysfunction of bone tissue. We recently discovered that the disorganized collagen/apatite microstructure in cancer-bearing bone is a dominant determinant of the disruption of bone mechanical function; disordered osteoblast arrangement was found to be one of the principal determinants of the deteriorated collagen/apatite microstructure. However, the precise molecular mechanisms regulating the disordered osteoblast arrangement triggered by cancer invasion are not yet understood. Herein, we demonstrate a significant disorganization of bone tissue anisotropy in metastasized bone in our novel ex vivo metastasis model. Further, we propose a novel mechanism underlying the disorganization of a metastasized bone matrix: A dynamic collision behavior between tumor cells and osteoblasts disturbs the osteoblast arrangement along the collagen substrate.

NPNT promotes early-stage bone metastases in breast cancer by regulation of the osteogenic niche

Patients with breast cancer are often afflicted by bone metastases, while the establishment and growth of bone metastases depend on interaction between cancer cells and the host environment. Moreover, osteoblasts, which play a vital role in cancer cells survival and colonization, can form an osteogenic niche in early stage of bone metastases. Also, it is widely accepted that there is a genetic determinant during bone metastases. Nephronectin (NPNT) is an extracellular matrix protein which has shown biological activities in breast cancer metastases and osteoblasts differentiation. But the role of NPNT in mediating breast cancer bone metastases remains elusive. In the present study, we revealed that up regulation of NPNT is associated with incidence of bone metastases. What's more, NPNT could significantly enhance the tumor cell clone formation but not proliferation and migration. We further demonstrated that NPNT significantly enhance osteoblast differentiation and tumor adhesion. Thus, we proposed that cancer secreted NPNT may be a novel marker with potential value of prediction and diagnosis of breast cancer bone metastases.

Spectrum of lytic lesions of the skull: a pictorial essay

Abstract

Lytic lesions of the skull include a wide range of diseases, ranging from benign conditions such as arachnoid granulations or vascular lacunae, to aggressive malignant lesions such as lymphomas or metastases. An early and correct characterisation of the nature of the lesion is, therefore, crucial, in order to achieve a fast and appropriate treatment option. In this review, we present the radiological appearance of the most frequent lytic lesions of the skull, describing findings from different imaging modalities (plain X-rays, CT and MRI), with particular attention to diagnostic clues and differential diagnoses.

Teaching Points

• Osteolytic skull lesions may be challenging to diagnose.

• Association of different imaging techniques may aid image interpretation.

• Clinical information and extensive knowledge of possible differential diagnoses is essential.

• Some osteolytic tumours, although benign, may present as locally aggressive lesions.

• Malignant lesions require accurate staging, followed by variable treatment approaches.

The role of IL-1B in breast cancer bone metastasis

Approximately 75% of patients with late-stage breast cancer will develop bone metastasis. This condition is currently considered incurable and patients' life expectancy is limited to 2-3 years following diagnosis of bone involvement. Interleukin (IL)-1B is a pro-inflammatory cytokine whose expression in primary tumours has been identified as a potential biomarker for predicting breast cancer patients at increased risk for developing bone metastasis. In this review, we discuss how IL-1B from both the tumour cells and the tumour microenvironment influence growth of primary breast tumours, dissemination into the bone metastatic niche and proliferation into overt metastases. Recent evidence indicates that targeting IL-1B signalling may provide promising new treatments that can hold tumour cells in a dormant state within bone thus preventing formation of overt bone metastases.

Mesenchymal Stromal Cells: Emerging Roles in Bone Metastasis

Bone metastasis is the most advanced stage of many cancers and indicates a poor prognosis for patients due to resistance to anti-tumor therapies. The establishment of metastasis within the bone is a multistep process. To ensure survival within the bone marrow, tumor cells must initially colonize a niche in which they can enter dormancy. Subsequently, reactivation permits the proliferation and growth of the tumor cells, giving rise to a macro-metastasis displayed clinically as a bone metastatic lesion. Here, we review the evidences that suggest mesenchymal stromal cells play an important role in each of these steps throughout the development of bone metastasis. Similarities between the molecular mechanisms implicated in these processes and those involved in the homeostasis of the bone indicate that the metastatic cells may exploit the homeostatic processes to their own advantage. Identifying the molecular interactions between the mesenchymal stromal cells and tumor cells that promote tumor development may offer insight into potential therapeutic targets that could be utilized to treat bone metastasis.

Established Models and New Paradigms for Hypoxia-Driven Cancer-Associated Bone Disease

The five-year survival rate for primary bone cancers is ~ 70% while almost all cases of secondary metastatic bone cancer are terminal. Hypoxia, the deficiency of oxygen which occurs as the rate of tumour growth exceeds the supply of vascularisation, is a key promoter of tumour progression. Hypoxia-driven effects in the primary tumour are wide ranging including changes in gene expression, dysregulation of signalling pathways, resistance to chemotherapy, neovascularisation, increased tumour cell proliferation and migration. Paget's seed and soil theory states that for a metastasising tumour cell 'the seed' it requires the correct microenvironment 'soil' to colonise. Why and how metastasising tumour cells colonise the bone is a complex and intriguing problem. However, once present tumour cells are able to disrupt bone homeostasis through increasing osteoclast activity and downregulating osteoblast function. Osteoclast resorption releases growth factors from the bone matrix that subsequently contribute to the proliferation of invasive tumour cells creating the vicious cycle of bone loss and metastatic cancer progression. Recently, we have shown that hypoxia increases expression and release of lysyl oxidase (LOX) from primary mammary tumours, which in turn disrupts bone homeostasis to favour osteolytic degradation to create pre-metastatic niches in the bone microenvironment. We also demonstrated how treatment with bisphosphonates could block this cancer-induced bone remodelling and reduce secondary bone metastases. This review describes the roles of hypoxia in primary tumour progression to metastasis, with a focus on key signalling pathways and treatment options to reduce patient morbidity and increase survival.

The anti-tumor effect of RANKL inhibition in malignant solid tumors - A systematic review

At present, accumulating evidence suggests that inhibition of receptor activator of nuclear factor kappa-B ligand (RANKL) does not only induce an increase in bone mass and strength, but also has anti-tumor effects. Denosumab, an antibody targeting RANKL, is used to treat osteoporosis and to prevent skeletal related events (SREs) in patients with bone metastases originating from solid tumors. However, expression of RANKL and its receptor activator of nuclear factor kappa-B (RANK) is not solely restricted to cells involved in homeostasis of the bone and RANKL-RANK signalling appears to play a substantial role in many other processes in the body like mammary physiology, mammary tumorigenesis and the immune system. In pre-clinical models, RANKL inhibition has been shown to reduce skeletal tumor burden and distant metastases as well as to decrease mammary carcinogenesis. Clinically, RANKL inhibition improves bone-metastasis free survival in patients with prostate cancer and disease-free survival in patients with breast cancer. In addition, RANKL treatment may form a preventative strategy in patients at high risk for malignancies of the breast. Current clinical studies are evaluating the effect of denosumab on survival, the immune system and other biomarkers into a greater extent. To that purpose, a systematic review of the literature was performed and a narrative review synthesized, describing the present pre-clinical and clinical evidence of an anti-tumor effect of RANKL inhibition and the potential role of the immune system as one of the underlying mechanisms.

Identification of Fibulin-1 as a Human Bone Marrow Stromal (HS-5) Cell-Derived Factor That Induces Human Prostate Cancer Cell Death

BACKGROUND

Previous studies showed that human bone marrow stromal HS-5 cells secreted unidentified factor(s) inducing PCa cell death. Herein, the HS-5-derived factor (HS-5 DF) was characterized and identified.

METHODS

Conditioned media from confluent HS-5 cells were collected and modified for biochemical characteristic testing of HS-5 DF. Cell survival was measured by apoptosis assay and live/dead assay. Fibulin-1 was identified from gel electrophoresis and mass spectrometry. The validation of Fibulin-1 as a HS-5 DF was done by immunoprecipitation (IP) and genetic knockdown by CRISPR/Cas9 system.

RESULTS

HS-5 DF was trypsin and heat sensitive, but pH stable. The tentative size of the factor fell between 30 kDa and 100 kDa. TGF-β1 treatment led to a suppression of HS-5 DF activity, a property consistent with bone metastasis in prostate cancer. Examination of TGF-β1 down regulated proteins led to identification of fibulin-1 as a candidate for the DF. IP of Fibulin-1 from HS-5 CM and CRISPR knockdown of Fibulin-1 showed a significant reduction of HS-5 CM-derived PCa cell death. These results strongly support a role for fibulin-1 in HS-5 bone marrow stromal cell induction of PCa cell death.

CONCLUSION

Our data indicate that Fibulin-1 functions as a HS-5 bone marrow stromal cell-derived factor inducing prostate cancer cell death. Prostate 77:729-742, 2017. © 2016 Wiley Periodicals, Inc.

Ayurvedic concept of Shatkriyakala: a traditional knowledge of cancer pathogenesis and therapy

The term Kriyakala refers to the recognition of the stage of a disease's progress, which helps to determine appropriate measure to correct the imbalance in Doshas (biological factors). It is a compound expression, comprised of Kriya and Kala, where Kriya means the choice to treatment (medicine, food and daily-routine) used to improve the disturbance in Doshas, and Kala refers to the stage of progress of a disease. Sushruta, an ancient Indian surgeon, has described the concept of Kriyakala in Varnaprashnadhyaya, an ancient Vedic Sanskrit text, which seeks to explain the incidence of Varnas in terms of Doshic disturbances. Varna, in modern parlance, may be described as an inflammatory process that may lead ulceration and chronic inflammation, promoting all stages of carcinogenesis. Abnormal interactions between Prakriti (genotype) and environmental factors vitiate the Doshas and impair immunity, which can lead to aberrant cell growth and cancer. Moreover, the interaction between vitiated Doshas and weak Dhatus (body tissues) manifests as cancers of a specific organ. Shatkriyakala (six stages of progress of a disease), on the other hand, provides a framework to assess the cancer and its pathogenesis in different stages. According to Ayurvedic concepts, all cancer therapies treat the affected tissues indirectly by eliminating vitiated Doshas, rejuvenating Dhatus and restoring immunity in cancer patients. The present review describes the six stages of Shatkriyakala in detail, with an emphasis on research areas to validate the concept of Shatkriyakala. This traditional knowledge can be utilized with modern technologies to detect predisposition for cancer or diagnose cancer in its early stages.

Disseminated tumor cells and dormancy in prostate cancer metastasis

It has been reported that disseminated tumor cells (DTCs) can be found in the majority of prostate cancer (PCa) patients, even at the time of primary treatment with no clinical evidence of metastatic disease. This suggests that these cells escaped the primary tumor early in the disease and exist in a dormant state in distant organs until they develop in some patients as overt metastases. Understanding the mechanisms by which cancer cells exit the primary tumor, survive the circulation, settle in a distant organ, and exist in a quiescent state is critical to understanding tumorigenesis, developing new prognostic assays, and designing new therapeutic modalities to prevent and treat clinical metastases.

Biology of Bone Metastases in Prostate Cancer

Advanced-stage prostate cancer (PCa) patients are often diagnosed with bone metastases. Bone metastases remain incurable and therapies are palliative. PCa cells prevalently cause osteoblastic lesions, characterized by an excess of bone formation. The prevailing concept indicates that PCa cancer cell secrete an excess of paracrine factors stimulating osteoblasts directly or indirectly, thereby leading to an excess of bone formation. The exact mechanisms by which bone formation stimulates PCa cell growth are mostly elusive. In this review, the mechanisms of PCa cancer cell osteotropism, the cancer cell-induced response within the bone marrow/bone stroma, and therapeutic stromal targets will be summarized.

Skeletal metastases from breast cancer: pathogenesis of bone tropism and treatment strategy

Breast cancer (BC) is the most common female cancer worldwide with approximately 10 % of new cases metastatic at diagnosis and 20-50 % of patients with early BC who will eventually develop metastatic disease. Bone is the most frequent site of colonisation and the development of skeletal metastases depends on a complex multistep process, from dissemination and survival of malignant cells into circulation to the actual homing and metastases formation inside bone. Disseminated tumor cells (DTCs) can be detected in bone marrow in approximately 30 % of BC patients, likely reflecting the presence of minimal residual disease that would eventually account for subsequent metastatic disease. Patients with bone marrow DTCs have poorer overall survival compared with patients without them. Although bone-only metastatic disease seems to have a rather indolent behavior compared to visceral disease, bone metastases can cause severe and debilitating effects, including pain, spinal cord compression, hypercalcemia and pathologic fractures. Delivering an appropriate treatment is therefore paramount and ideally it should require interdisciplinary care. Multiple options are currently available, from bisphosphonates to new drugs targeting RANK ligand and radiotherapy. In this review we describe the mechanisms underlying bone colonization and provide an update on existing systemic and locoregional treatments for bone metastases.

Pilot study of adoptive immunotherapy with sentinel node-derived T cells in muscle-invasive urinary bladder cancer

OBJECTIVE

The aim of this study was to determine by computed tomography (CT) whether treatment with tumor-draining lymph-node-derived expanded autologous T lymphocytes results in objective responses and/or improved survival in patients with metastatic urinary bladder cancer (UBC) and to record the toxicity of the treatment.

MATERIALS AND METHODS

Eighteen patients with metastatic UBC were prospectively selected from two centers. The preoperative staging was T2-T4bN1-2 and/or M0-M1 or MX. Tumor-draining lymph nodes were harvested at intended cystectomy for the extraction of T lymphocytes. This was followed by expansion of the T lymphocytes in a cell culture, and subsequent reinfusion of these autologous tumor-specific T lymphocytes. Responses to therapy were evaluated by CT scans according to Response Evaluation Criteria In Solid Tumors (RECIST) and clinical follow-up, according to the research protocol.

RESULTS

Nine out of 18 patients were treated. Treatment was feasible and safe. In two out of nine immunologically treated patients, objective responses were detected in terms of diminished or obliterated nodal metastases. When excluding three patients with disseminated osseous metastases plus one with a T4b tumor left in situ, a success rate of two out of six treated patients was seen. The two responders had survival times of 35 and 11 months, respectively. No toxicity was recorded.

CONCLUSIONS

Infusion of expanded autologous tumor-specific T lymphocytes is feasible and safe, and objective responses according to RECIST were recorded. One objective responder to immunotherapy displayed notably long overall survival.

Mesenchymal stromal cell secretome up-regulates 47 kDa CXCR4 expression, and induce invasiveness in neuroblastoma cell lines

Neuroblastoma accounts for 15% of childhood cancer deaths and presents with metastatic disease of the bone and the bone marrow at diagnosis in 70% of the cases. Previous studies have shown that the Mesenchymal Stromal Cell (MSC) secretome, triggers metastases in several cancer types such as breast and prostate cancer, but the specific role of the MSC factors in neuroblastoma metastasis is unclear. To better understand the effect of MSC secretome on chemokine receptors in neuroblastoma, and its role in metastasis, we studied a panel of 20 neuroblastoma cell lines, and compared their invasive potential towards MSC-conditioned-RPMI (mRPMI) and their cytokine receptor expression profiles. Western blot analysis revealed the expression of multiple CXCR4 isoforms in neuroblastoma cells. Among the five major isoforms, the expression of the 47 kDa isoform showed significant correlation with high invasiveness. Pretreatment with mRPMI up-regulated the expression of the 47 kDa CXCR4 isoform and also increased MMP-9 secretion, expression of integrin α3 and integrin β1, and the invasive potential of the cell; while blocking CXCR4 either with AMD 3100, a CXCR4 antagonist, or with an anti-47 kDa CXCR4 neutralizing antibody decreased the secretion of MMP-9, the expression of integrin α3 and integrin β1, and the invasive potential of the cell. Pretreatment with mRPMI also protected the 47 kDa CXCR4 isoform from ubiquitination and subsequent degradation. Our data suggest a modulatory role of the MSC secretome on the expression of the 47 kDa CXCR4 isoform and invasion potential of the neuroblastoma cells to the bone marrow.

Tissue engineering a surrogate niche for metastatic cancer cells

In breast and prostate cancer patients, the bone marrow is a preferred site of metastasis. We hypothesized that we could use tissue-engineering strategies to lure metastasizing cancer cells to tissue-engineered bone marrow. First, we generated highly porous 3D silk scaffolds that were biocompatible and amenable to bone morphogenetic protein 2 functionalization. Control and functionalized silk scaffolds were subcutaneously implanted in mice and bone marrow development was followed. Only functionalized scaffolds developed cancellous bone and red bone marrow, which appeared as early as two weeks post-implantation and further developed over the 16-week study period. This tissue-engineered bone marrow microenvironment could be readily manipulated in situ to understand the biology of bone metastasis. To test the ability of functionalized scaffolds to serve as a surrogate niche for metastasis, human breast cancer cells were injected into the mammary fat pads of mice. The treatment of animals with scaffolds had no significant effect on primary tumor growth. However, extensive metastasis was observed in functionalized scaffolds, and the highest levels for scaffolds that were in situ manipulated with receptor activator of nuclear factor kappa-B ligand (RANKL). We also applied this tissue-engineered bone marrow model in a prostate cancer and experimental metastasis setting. In summary, we were able to use tissue-engineered bone marrow to serve as a target or "trap" for metastasizing cancer cells.

Biochemical evidence for Ca2+-independent functional activation of hPLSCR1 at low pH

Human phospholipid scramblase 1 (hPLSCR1) is a Ca

The host microenvironment influences prostate cancer invasion, systemic spread, bone colonization, and osteoblastic metastasis

Prostate cancer (PCa) is the second leading cause of cancer death in men worldwide. Most PCa deaths are due to osteoblastic bone metastases. What triggers PCa metastasis to the bone and what causes osteoblastic lesions remain unanswered. A major contributor to PCa metastasis is the host microenvironment. Here, we address how the primary tumor microenvironment influences PCa metastasis via integrins, extracellular proteases, and transient epithelia-mesenchymal transition (EMT) to promote PCa progression, invasion, and metastasis. We discuss how the bone-microenvironment influences metastasis; where chemotactic cytokines favor bone homing, adhesion molecules promote colonization, and bone-derived signals induce osteoblastic lesions. Animal models that fully recapitulate human PCa progression from primary tumor to bone metastasis are needed to understand the PCa pathophysiology that leads to bone metastasis. Better delineation of the specific processes involved in PCa bone metastasize is needed to prevent or treat metastatic PCa. Therapeutic regimens that focus on the tumor microenvironment could add to the PCa pharmacopeia.

Biomechanical forces in the skeleton and their relevance to bone metastasis: biology and engineering considerations

Bone metastasis represents the leading cause of breast cancer related-deaths. However, the effect of skeleton-associated biomechanical signals on the initiation, progression, and therapy response of breast cancer bone metastasis is largely unknown. This review seeks to highlight possible functional connections between skeletal mechanical signals and breast cancer bone metastasis and their contribution to clinical outcome. It provides an introduction to the physical and biological signals underlying bone functional adaptation and discusses the modulatory roles of mechanical loading and breast cancer metastasis in this process. Following a definition of biophysical design criteria, in vitro and in vivo approaches from the fields of bone biomechanics and tissue engineering that may be suitable to investigate breast cancer bone metastasis as a function of varied mechano-signaling will be reviewed. Finally, an outlook of future opportunities and challenges associated with this newly emerging field will be provided.

Pivotal role of pervasive neoplastic and stromal cells reprogramming in circulating tumor cells dissemination and metastatic colonization

Reciprocal interactions between neoplastic cells and their microenvironment are crucial events in carcinogenesis and tumor progression. Pervasive stromal reprogramming and remodeling that transform a normal to a tumorigenic microenvironment modify numerous stromal cells functions, status redox, oxidative stress, pH, ECM stiffness and energy metabolism. These environmental factors allow selection of more aggressive cancer cells that develop important adaptive strategies. Subpopulations of cancer cells acquire new properties associating plasticity, stem-like phenotype, unfolded protein response, metabolic reprogramming and autophagy, production of exosomes, survival to anoikis, invasion, immunosuppression and therapeutic resistance. Moreover, by inducing vascular transdifferentiation of cancer cells and recruiting endothelial cells and pericytes, the tumorigenic microenvironment induces development of tumor-associated vessels that allow invasive cells to gain access to the tumor vessels and to intravasate. Circulating cancer cells can survive in the blood stream by interacting with the intravascular microenvironment, extravasate through the microvasculature and interact with the metastatic microenvironment of target organs. In this review, we will focus on many recent paradigms involved in the field of tumor progression.