Gefitinib inhibits the ability of human bone marrow stromal cells to induce osteoclast differentiation: implications for the pathogenesis and treatment of bone metastasis

Research progress of the chemokine/chemokine receptor axes in the oncobiology of multiple myeloma (MM)

BACKGROUND

The incidence of multiple myeloma (MM), a type of blood cancer affecting monoclonal plasma cells, is rising. Although new drugs and therapies have improved patient outcomes, MM remains incurable. Recent studies have highlighted the crucial role of the chemokine network in MM's pathological mechanism. Gaining a better understanding of this network and creating an overview of chemokines in MM could aid in identifying potential biomarkers and developing new therapeutic strategies and targets.

PURPOSE

To summarize the complicated role of chemokines in MM, discuss their potential as biomarkers, and introduce several treatments based on chemokines.

METHODS

Pubmed, Web of Science, ICTRP, and Clinical Trials were searched for articles and research related to chemokines. Publications published within the last 5 years are selected.

RESULTS

Malignant cells can utilize chemokines, including CCL2, CCL3, CCL5, CXCL7, CXCL8, CXCL12, and CXCL13 to evade apoptosis triggered by immune cells or medication, escape from bone marrow and escalate bone lesions. Other chemokines, including CXCL4, CCL19, and CXCL10, may aid in recruiting immune cells, increasing their cytotoxicity against cancer cells, and inducing apoptosis of malignant cells.

CONCLUSION

Utilizing anti-tumor chemokines or blocking pro-tumor chemokines may provide new therapeutic strategies for managing MM. Inspired by developed CXCR4 antagonists, including plerixafor, ulocuplumab, and motixafortide, more small molecular antagonists or antibodies for pro-tumor chemokine ligands and their receptors can be developed and used in clinical practice. Along with inhibiting pro-tumor chemokines, studies suggest combining chemokines with chimeric antigen receptor (CAR)-T therapy is promising and efficient.

Osteoblastic bone reaction in non-small cell lung cancer harboring epidermal growth factor receptor mutation treated with osimertinib

BACKGROUND

Osteoblastic bone reaction (OBR) refers to an increase in bone density at the site of bone metastasis or the appearance of new sclerotic bone lesions after anticancer treatment. OBR can be misunderstood as disease progression. In this study, we aimed to investigate the prevalence and details of OBR and its association with clinical outcomes in patients with epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) treated with osimertinib.

METHODS

This was a single-center, retrospective cohort study. We reviewed patients who were diagnosed with EGFR-mutant NSCLC with bone metastasis and received osimertinib as a first-line treatment between February 2018 and October 2022. The OBR was evaluated by comparing baseline computed tomography (CT) scans with the first CT scan after treatment initiation.

RESULTS

A total of 45 patients were included in this study. Thirty-seven patients (82%) developed OBR. OBR developed in 94% (n = 16) of patients with sclerotic bone lesions (n = 17) at baseline. Similarly, OBR developed in lytic and mixed bone lesions in 76% and 82% of patients with lytic and mixed lesions, respectively. Progression-free survival (PFS) did not differ significantly between patients with (OBR group) and without OBR (non-OBR group) (median PFS, 24 months vs. 17 months; hazard ratio (HR), 0.62; 95% CI, 0.24-1.6; p = 0.31). In univariate analysis, the OBR group showed a trend toward longer skeletal-related events-free survival (SRE-FS) than the non-OBR group (median SRE-FS, 26 months vs. 12 months; HR, 0.53; 95% CI, 0.21-1.33; p = 0.16). Multivariate analysis showed OBR was a significant independent predictor of SRE-FS (HR, 0.35; 95% CI, 0.13-0.92; p = 0.034).

CONCLUSIONS

OBR developed in most patients with NSCLC and bone metastasis who received osimertinib treatment. The increased incidence of OBR in patients with EGFR-mutant NSCLC with bone metastasis treated with osimertinib should not be confused with disease progression, and treatment decisions should be made carefully.

Osteosclerotic change as a therapeutic response to gefitinib in symptomatic non-small cell lung cancer bone metastasis

BACKGROUND

Despite improvement in the overall survival of patients with non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutation, the effects of EGFR tyrosine kinase inhibitor (EGFR-TKI) treatment on bone metastasis remain unclear. This study investigated radiological responses to gefitinib regarding bone metastasis in patients.

METHODS

We treated 260 patients with NSCLC and symptomatic bone metastasis. Thirty-seven patients harboring EGFR mutation were treated with gefitinib for more than 30 days and followed up for more than 3 months (GEF group). We performed a retrospective observational study by selecting 36 cases without EGFR-TKI treatment, at least 3 months of follow-up, and at least two radiological evaluations as the control group. We assessed the best overall radiological response, interval from treatment initiation to appearance of a radiological response, and the local response maintenance rate.

RESULTS

The best effect in the GEF group was 98% partial response or better, which was significantly higher than the 57% observed in the control group (p < 0.001). The GEF and control groups maintained 83% and 42% local response maintenance rates at one year, respectively (p < 0.001). In the GEF with radiotherapy group, the local response maintenance rate was maintained at 92% at 1 year, while in the GEF without RT group, there was a decrease in the local response maintenance rate from 270 days.

CONCLUSION

Gefitinib treatment for bone metastases in patients harboring EGFR mutation resulted in a beneficial osteosclerotic change in most patients. Combined gefitinib and radiotherapy provide long-lasting local control of bone metastases.

Transcription Factors STAT3 and MYC Are Key Players of Human Platelet Lysate-Induced Cell Proliferation

Human platelet lysate (HPL) is an efficient alternative for animal serum supplements, significantly enhancing stromal cell proliferation. However, the molecular mechanism behind this growth-promoting effect remains elusive. The aim of this study was to investigate the effect of HPL on cell cycle gene expression in different human stromal cells and to identify the main key players that mediate HPL's growth-enhancing effect. RT-qPCR and an antibody array revealed significant upregulation of cell cycle genes in stromal cells cultured in HPL. As HPL is rich in growth factors that are ligands of tyrosine kinase receptor (TKR) pathways, we used TKR inhibitors and could significantly reduce cell proliferation. Genome profiling, RT-qPCR and Western blotting revealed an enhanced expression of the transcription factors signal transducer and activator of transcription 3 (STAT3) and MYC, both known TKR downstream effectors and stimulators of cell proliferation, in response to HPL. In addition, specifically blocking STAT3 resulted in reduced cell proliferation and expression of cell cycle genes. Our data indicate that HPL-enhanced cell proliferation can, at least in part, be explained by the TKR-enhanced expression of STAT3 and MYC, which in turn induce the expression of genes being involved in the promotion and control of the cell cycle.

Osteoblasts and osteoclasts: an important switch of tumour cell dormancy during bone metastasis

Bone metastasis occurs when tumour cells dissociate from primary tumours, enter the circulation (circulating tumour cells, CTCs), and colonize sites in bone (disseminated tumour cells, DTCs). The bone marrow seems to be a particularly dormancy-inducing environment for DTCs, yet the mechanisms of dormancy initiation, reactivation, and interaction within the bone marrow have to be elucidated. Intriguingly, some evidence has suggested that dormancy is a reversible state that is switched 'on' or 'off' depending on the presence of various bone marrow resident cells, particularly osteoclasts and osteoblasts. It has become clear that these two cells contribute to regulating dormant tumour cells in bone both directly (interaction) and indirectly (secreted factors). The involved mechanisms include TGFβ signalling, the Wnt signalling axis, the Notch2 pathway, etc. There is no detailed review that specifically focuses on ascertaining the dynamic interactions between tumour cell dormancy and bone remodelling. In addition, we highlighted the roles of inflammatory cytokines during this 'cell-to-cell' communication. We also discussed the potential clinical relevance of remodelling the bone marrow niche in controlling dormant tumour cells. Understanding the unique role of osteoclasts and osteoblasts in regulating tumour dormancy in bone marrow will provide new insight into preventing and treating tumour bone metastasis.

Multiple Myeloma Cell-Derived Exosomes: Implications on Tumorigenesis, Diagnosis, Prognosis and Therapeutic Strategies

Multiple myeloma (MM) is a hematological disease that is still not curable. The bone marrow milieu, with cellular and non-cellular elements, participate in the creation of a pro-tumoral environment enhancing growth and survival of MM plasma cells. Exosomes are vesicles oscillating in dimension between 50 nm and 100 nm in size that can be released by various cells and contribute to the pathogenesis and progression of MM. Exosomes enclose proteins, cytokines, lipids, microRNAs, long noncoding RNAs, and circular RNAs able to regulate interactions between MM plasma cells and adjacent cells. Through exosomes, mesenchymal stem cells confer chemoresistance to MM cells, while myeloma cells promote angiogenesis, influence immune response, cause bone lesions, and have an impact on the outcome of MM patients. In this review, we analyze the role played by exosomes in the progression of monoclonal gammopathies and the effects on the proliferation of neoplastic plasma cells, and discuss the possible employment of exosomes as potential targets for the treatment of MM patients.

AKT in Bone Metastasis of Solid Tumors: A Comprehensive Review

Simple Summary

Bone metastasis is a frequent complication of solid tumors and leads to a reduced overall survival. Although much progress has been made in the field of tumor therapy in the last years, bone metastasis depicts a stage of the disease with a lack of appropriate therapeutical options. Hence, this review aims to present the role of AKT in bone metastasis of solid tumors to place the spotlight on AKT as a possible therapeutical approach for patients with bone metastases. Furthermore, we intended to discuss postulated underlying molecular mechanisms of the bone metastasis-promoting effect of AKT, especially in highly bone-metastatic breast, prostate, and lung cancer. To conclude, this review identified the AKT kinase as a potential therapeutical target in bone metastasis and revealed remaining questions, which need to be addressed in further research projects.

Abstract

Solid tumors, such as breast cancer and prostate cancer, often form bone metastases in the course of the disease. Patients with bone metastases frequently develop complications, such as pathological fractures or hypercalcemia and exhibit a reduced life expectancy. Thus, it is of vital importance to improve the treatment of bone metastases. A possible approach is to target signaling pathways, such as the PI3K/AKT pathway, which is frequently dysregulated in solid tumors. Therefore, we sought to review the role of the serine/threonine kinase AKT in bone metastasis. In general, activation of AKT signaling was shown to be associated with the formation of bone metastases from solid tumors. More precisely, AKT gets activated in tumor cells by a plethora of bone-derived growth factors and cytokines. Subsequently, AKT promotes the bone-metastatic capacities of tumor cells through distinct signaling pathways and secretion of bone cell-stimulating factors. Within the crosstalk between tumor and bone cells, also known as the vicious cycle, the stimulation of osteoblasts and osteoclasts also causes activation of AKT in these cells. As a consequence, bone metastasis is reduced after experimental inhibition of AKT. In summary, AKT signaling could be a promising therapeutical approach for patients with bone metastases of solid tumors.

The Therapeutic Potential of Mesenchymal Stromal Cells in the Treatment of Chemotherapy-Induced Tissue Damage

Chemotherapy constitutes one of the key treatment modalities for solid and hematological malignancies. Albeit being an effective treatment, chemotherapy application is often limited by its damage to healthy tissues, and curative treatment options for chemotherapy-related side effects are largely missing. As mesenchymal stromal cells (MSCs) are known to exhibit regenerative capacity mainly by supporting a beneficial microenvironment for tissue repair, MSC-based therapies may attenuate chemotherapy-induced tissue injuries. An increasing number of animal studies shows favorable effects of MSC-based treatments; however, clinical trials for MSC therapies in the context of chemotherapy-related side effects are rare. In this concise review, we summarize the current knowledge of the effects of MSCs on chemotherapy-induced tissue toxicities. Both preclinical and early clinical trials investigating MSC-based treatments for chemotherapy-related side reactions are presented, and mechanistic explanations about the regenerative effects of MSCs in the context of chemotherapy-induced tissue damage are discussed. Furthermore, challenges of MSC-based treatments are outlined that need closer investigations before these multipotent cells can be safely applied to cancer patients. As any pro-tumorigenicity of MSCs needs to be ruled out prior to clinical utilization of these cells for cancer patients, the pro- and anti-tumorigenic activities of MSCs are discussed in detail.

A Flare for the Unexpected: Bone Flare as Response to Tyrosine Kinase Inhibitor Treatment in a Lung Cancer Patient: New osteoblastic bone lesions in a lung cancer patient may represent bone flare and should not be misdiagnosed as disease progression

We report the case of a 72-year-old female never-smoker with stage IV endothelial growth factor receptor (EGFR) mutated lung adenocarcinoma. This patient was started on first line tyrosine kinase inhibitor (TKI) and seemingly developed new bone metastases under this treatment. As there was a remarkable discrepancy between the partial response seen in the primary tumor and non-osseous metastatic locations, the possibility of a bone flare phenomenon was considered. In this case report, we demonstrate that new bony lesions are not always synonymous with disease progression.

Biologically driven cut-off definition of lymphocyte ratios in metastatic breast cancer and association with exosomal subpopulations and prognosis

High neutrophil to lymphocyte ratio (NLR) and monocyte to lymphocyte ratio (MLR) are respectively associated with systemic inflammation and immune suppression and have been associated with a poor outcome. Plasmatic exosomes are extracellular vesicles involved in the intercellular communication system that can exert an immunosuppressive function. Aim of this study was to investigate the interplay between the immune system and circulating exosomes in metastatic breast cancer (MBC). A threshold capable to classify patients according to MLR, NLR and PLR, was computed through a receiving operator curve analysis after propensity score matching with a series of female blood donors. Exosomes were isolated from plasma by ExoQuick solution and characterized by flow-cytometry. NLR, MLR, PLR and exosomal subpopulations potentially involved in the pre-metastatic niche were significantly different in MBC patients with respect to controls. MLR was significantly associated with number of sites at the onset of metastatic disease, while high levels of MLR and NLR were found to be associated with poor prognosis. Furthermore, exosomal subpopulations varied according to NLR, MLR, PLR and both were associated with different breast cancer subtypes and sites of distant involvement. This study highlights the nuanced role of immunity in MBC spread, progression and outcome. Moreover, they suggest potential interaction mechanisms between immunity, MBC and the metastatic niche.

Tiliroside is a new potential therapeutic drug for osteoporosis in mice

Osteoporosis is a class of metabolic bone disease caused by complexed ramifications. Overactivation of osteoclasts due to a sudden decreased estrogen level plays a pivotal role for postmenopausal women suffering from osteoporosis. Therefore, inhibiting osteoclast formation and function has become a major direction for the treatment of osteoporosis. Tiliroside (Tle) is a salutary dietary glycosidic flavonoid extracted from Oriental Paperbush flower, which has been reported to have an anti-inflammation effect. However, whether Tle affects the osteoclastogenesis and bone resorption remains unknown. Herein, we demonstrate that Tle prevents bone loss in ovariectomy in mice and inhibits osteoclast differentiation and bone resorption stimulated by receptor activator of nuclear factor-κB ligand (RANKL) in vitro. Molecular mechanism studies reveal that Tle reduces RANKL-induced activation of mitogen-activated protein kinase and T-cell nuclear factor 1 pathways, and osteoclastogenesis-related marker gene expression, including cathepsin K (Ctsk), matrix metalloproteinase 9, tartrate-resistant acid phosphatase (Acp5), and Atp6v0d2. Our research indicates that Tle suppresses osteoclastogenesis and bone loss by downregulating the RANKL-mediated signaling protein activation and expression. In addition, Tle inhibits intracellular reactive oxygen species generation which is related to the formation of osteoclasts. Therefore, Tle might serve as a potential drug for osteolytic disease such as osteoporosis.

Multiple myeloma-derived exosomes are enriched of amphiregulin (AREG) and activate the epidermal growth factor pathway in the bone microenvironment leading to osteoclastogenesis

Background

Multiple myeloma (MM) is a clonal plasma cell malignancy associated with osteolytic bone disease. Recently, the role of MM-derived exosomes in the osteoclastogenesis has been demonstrated although the underlying mechanism is still unknown. Since exosomes-derived epidermal growth factor receptor ligands (EGFR) are involved in tumor-associated osteolysis, we hypothesize that the EGFR ligand amphiregulin (AREG) can be delivered by MM-derived exosomes and participate in MM-induced osteoclastogenesis.

Methods

Exosomes were isolated from the conditioned medium of MM1.S cell line and from bone marrow (BM) plasma samples of MM patients. The murine cell line RAW264.7 and primary human CD14⁺ cells were used as osteoclast (OC) sources.

Results

We found that AREG was specifically enriched in exosomes from MM samples and that exosomes-derived AREG led to the activation of EGFR in pre-OC, as showed by the increase of mRNA expression of its downstream SNAIL in both RAW264.7 and CD14⁺ cells. The presence of neutralizing anti-AREG monoclonal antibody (mAb) reverted this effect. Consequently, we showed that the effect of MM-derived exosomes on osteoclast differentiation was inhibited by the pre-treatment of exosomes with anti-AREG mAb. In addition, we demonstrated the ability of MM-derived AREG-enriched exosomes to be internalized into human mesenchymal stromal cells (MSCs) blocking osteoblast (OB) differentiation, increasing MM cell adhesion and the release of the pro-osteoclastogenic cytokine interleukin-8 (IL8). Accordingly, anti-AREG mAb inhibited the release of IL8 by MSCs suggesting that both direct and indirect effects are responsible for AREG-enriched exosomes involvement on MM-induced osteoclastogenesis.

Conclusions

In conclusion, our data indicate that AREG is packed into MM-derived exosomes and implicated in OC differentiation through an indirect mechanism mediated by OBs.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0689-y) contains supplementary material, which is available to authorized users.

How to Hit Mesenchymal Stromal Cells and Make the Tumor Microenvironment Immunostimulant Rather Than Immunosuppressive

Experimental evidence indicates that mesenchymal stromal cells (MSCs) may regulate tumor microenvironment (TME). It is conceivable that the interaction with MSC can influence neoplastic cell functional behavior, remodeling TME and generating a tumor cell niche that supports tissue neovascularization, tumor invasion and metastasization. In addition, MSC can release transforming growth factor-beta that is involved in the epithelial-mesenchymal transition of carcinoma cells; this transition is essential to give rise to aggressive tumor cells and favor cancer progression. Also, MSC can both affect the anti-tumor immune response and limit drug availability surrounding tumor cells, thus creating a sort of barrier. This mechanism, in principle, should limit tumor expansion but, on the contrary, often leads to the impairment of the immune system-mediated recognition of tumor cells. Furthermore, the cross-talk between MSC and anti-tumor lymphocytes of the innate and adaptive arms of the immune system strongly drives TME to become immunosuppressive. Indeed, MSC can trigger the generation of several types of regulatory cells which block immune response and eventually impair the elimination of tumor cells. Based on these considerations, it should be possible to favor the anti-tumor immune response acting on TME. First, we will review the molecular mechanisms involved in MSC-mediated regulation of immune response. Second, we will focus on the experimental data supporting that it is possible to convert TME from immunosuppressive to immunostimulant, specifically targeting MSC.

Tyrosine kinase inhibitors and mesenchymal stromal cells: effects on self-renewal, commitment and functions

The hope of selectively targeting cancer cells by therapy and eradicating definitively malignancies is based on the identification of pathways or metabolisms that clearly distinguish “normal” from “transformed” phenotypes. Some tyrosine kinase activities, specifically unregulated and potently activated in malignant cells, might represent important targets of therapy. Consequently, tyrosine kinase inhibitors (TKIs) might be thought as the “vanguard” of molecularly targeted therapy for human neoplasias. Imatinib and the successive generations of inhibitors of Bcr-Abl1 kinase, represent the major successful examples of TKI use in cancer treatment. Other tyrosine kinases have been selected as targets of therapy, but the efficacy of their inhibition, although evident, is less definite. Two major negative effects exist in this therapeutic strategy and are linked to the specificity of the drugs and to the role of the targeted kinase in non-malignant cells. In this review, we will discuss the data available on the TKIs effects on the metabolism and functions of mesenchymal stromal cells (MSCs). MSCs are widely distributed in human tissues and play key physiological roles; nevertheless, they might be responsible for important pathologies. At present, bone marrow (BM) MSCs have been studied in greater detail, for both embryological origins and functions. The available data are evocative of an unexpected degree of complexity and heterogeneity of BM-MSCs. It is conceivable that this grade of intricacy occurs also in MSCs of other organs. Therefore, in perspective, the negative effects of TKIs on MSCs might represent a critical problem in long-term cancer therapies based on such inhibitors.

Wenshen Zhuanggu formula effectively suppresses breast cancer bone metastases in a mouse Xenograft model

Wenshen Zhuanggu formula (WSZG) is a traditional Chinese medicine used as an adjuvant for the prevention of bone metastases in breast cancer patients. In this study we investigated the efficacy of WSZG in preventing bone metastases and the potential mechanisms in a mouse xenograft model of breast cancer bone metastases. This model was established by injection of human MDA-MB-231BO-Luc breast cancer cells alone or a mixture of the cancer cells with bone marrow-derived mesenchymal stem cells (BMSCs) into left ventricle of the heart in female nude mice. Then the mice were treated with WSZG (3.25, 6.5 or 13.0 mg·kg^-1·d^-1, ig) for four weeks, whereas zoledronic acid (100 μg/kg per week, ig) was used as a positive control. The occurrence and development of bone metastases were monitored via bioluminescent imaging, and bone lesions were assessed using micro-CT. Intracardiac injection of the mixture of MDA-MB-231BO-Luc breast cancer cells with BMSCs significantly facilitated the bone metastatic capacity of the breast cancer cells, and aggravated bone lesions in the mouse xenograft model of breast cancer bone metastases. Administration of WSZG dose-dependently inhibited the incidence and intensity of bone metastases and protected against bone lesions by suppressing osteoclast formation and tumor cell infiltration. Furthermore, administration of WSZG caused a marked reduction in the expression of CCL5/CCR5 and IL-17B/IL-17BR in bone metastatic tissues. The results demonstrate that WSZG exerts potential therapeutic effects in a mouse xenograft model of breast cancer bone metastases, which are partially mediated by weakening the interaction between BMSCs and breast cancer cells in the tumor microenvironment.

Tumor-Stroma Crosstalk in Bone Tissue: The Osteoclastogenic Potential of a Breast Cancer Cell Line in a Co-Culture System and the Role of EGFR Inhibition

Although bone metastases represent a major challenge in the natural history of breast cancer (BC), the complex interactions involved have hindered the development of robust in vitro models. The aim of this work is the development of a preclinical model of cancer and bone stromal cells to mimic the bone microenvironment. We studied the effects on osteoclastogenesis of BC cells and Mesenchymal stem cells (MSC) cultured alone or in combination. We also analyzed: (a) whether the blockade of the Epithelial Growth Factor Receptor (EGFR) pathway modified their influence on monocytes towards differentiation, and (b) the efficacy of bone-targeted therapy on osteoclasts. We evaluated the osteoclastogenesis modulation of human peripheral blood monocytes (PBMC) indirectly induced by the conditioned medium (CM) of the human BC cell line SCP2, cultured singly or with MSC. Osteoclastogenesis was evaluated by TRAP analysis. The effect of the EGFR blockade was assessed by treating the cells with gefitinib, and analyzed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Western Blot (WB). We observed that SCP2 co-cultured with MSC increased the differentiation of PBMC. This effect was underpinned upon pre-treatment of the co-culture with gefitinib. Co-culture of SCP2 with MSC increased the expression of both the bone-related marker Receptor Activator of Nuclear Factor κB (RANK) and EGFR in BC cells. These upregulations were not affected by the EGFR blockade. The effects of the CM obtained by the cells treated with gefitinib in combination with the treatment of the preosteoclasts with the bone-targeted agents and everolimus enhanced the inhibition of the osteoclastogenesis. Finally, we developed a fully human co-culture system of BC cells and bone progenitor cells. We observed that the interaction of MSC with cancer cells induced in the latter molecular changes and a higher power of inducing osteoclastogenesis. We found that blocking EGFR signaling could be an efficacious strategy for breaking the interactions between cancer and bone cells in order to inhibit bone metastasis.

RANK and EGFR in invasive breast carcinoma

Breast cancer is the most common malignancy, affecting one in eight women in North America and Europe. The human epidermal growth factor receptor (EGFR) protein comprises a major determinant of normal development but also cancer. RANK receptor (Receptor Activator of Nuclear factor-κB) is a tumor necrosis superfamily member and a binding partner for RANKL, which was recently implicated in breast cancer initiation, progression and metastasis. Here we provide preliminary evidence of a possible interplay between RANK and EGFR signaling in breast cancer. TCGA (cancergenome.nih.gov) publicly available data for EGFR and TNFRSF11A (RANK) genes from breast cancer patients and breast cancer cell lines were retrieved and analyzed. RANK mRNA showed a statistically significant positive correlation (p <0.001) with the mRNA and protein expression of EGFR, but not with ERBB2/3/4. Further analyses of survival data of a group of breast cancer patients (n = 248) from TCGA, revealed an EGFR^hi/RANK^hi subpopulation that showed a statistically significant (p = 0.001) reduced overall survival when compared to EGFR^low/RANK^low group of patients. Finally, EGFR and RANK combinatorial in vitro analyses revealed a significant upregulation of AKT and ERK signaling after EGF stimulation in cell lines and also an increase of breast cancer cell invasiveness.

Epidermal growth factor receptor is associated with the onset of skeletal related events in non-small cell lung cancer

Background

Bone metastasis and skeletal related events (SREs) are common in non-small cell lung cancer (NSCLC). Patients with mutant epidermal growth factor receptor (EGFR) could benefit from tyrosine kinase inhibitors (TKIs). However, it is unclear whether SRE is influenced by EGFR status. We aimed to evaluate the correlation of EGFR status and TKIs with the incidence of SREs.

Methods

We conducted a retrospective study of stage IV NSCLC patients with bone metastasis. Incidence rate of SREs was collected and was compared using chi-square test. Logistic-regression analysis was used to identify the risk factors predicting the incidence of SREs.

Results

410 eligible patients were enrolled in the study. 49.0% were detected with EGFR mutation. 49.8% of patients received EGFR-TKIs therapy prior to the onset of SREs. 42.7% experienced at least one SRE. Patients who were treated with TKIs held lower incidence of SREs than patients who were not treated with TKIs (23.5% vs 61.7%, p<0.001). Multivariate analysis showed that poor performance status (OR 5.550, 95%CI 2.290-13.450; p<0.001) and mutant EGFR (OR 3.050, 95%CI 1.608-5.787, p=0.001) were independent risk factors predicting the onset of SREs, while the usage of TKIs (OR 0.102, 95%CI 0.054-0.193, p<0.001) was a protective factor of SREs in NSCLC patients with bone metastasis.

Conclusions

This study indicates that the incidence of SREs is common in both patients with and without EGFR mutation. Poor performance ability and mutant EGFR imply higher risks of SREs, while the usage of TKIs may be a protective factor of SREs.

Afatinib ameliorates osteoclast differentiation and function through downregulation of RANK signaling pathways

Non-small-cell lung cancer (NSCLC) is the third most common cancer that spreads to the bone, resulting in osteolytic lesions caused by hyperactivation of osteoclasts. Activating mutations in epidermal growth factor receptor-tyrosine kinase (EGF-TK) are frequently associated with NSCLC, and afatinib is a first-line therapeutic drug, irreversibly targeting EGF-TK. However, the effects of afatinib on osteoclast differentiation and activation as well as the underlying mechanism remain unclear. In this study, afatinib significantly suppressed receptor activator of nuclear factor κB (RANK) ligand (RANKL)-induced osteoclast formation in bone marrow macrophages (BMMs). Consistently, afatinib inhibited the expression of osteoclast marker genes, whereas, it upregulated the expression of negative modulator genes. The bone resorbing activity of osteoclasts was also abrogated by afatinib. In addition, afatinib significantly inhibited RANKL-mediated Akt/protein kinase B and c-Jun N-terminal kinase phosphorylation. These results suggest that afatinib substantially suppresses osteoclastogenesis by downregulating RANK signaling pathways, and thus may reduce osteolysis after bone metastasis.

Osteoblastic progression during EGFR tyrosine kinase inhibitor therapy in mutated non-small cell lung cancer: a potential blunder

AIMS AND BACKGROUND

Bone flare reaction as a sign of response to antineoplastic treatment has been redefined, including the onset of new osteoblastic lesions. If misunderstood as skeletal progression, this finding could lead to erroneous therapy discontinuation, changing the disease clinical course. We aim to describe this clinical phenomenon in patients with advanced non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) gene-activating mutations treated with tyrosine kinase inhibitor (TKI).

METHODS

We retrospectively reviewed the computed tomography scans of 43 EGFR-mutated patients with NSCLC treated with EGFR-TKI, analyzing the bone response in terms of increase in the quantity and/or density of lesions, and assessing objective tumor response to treatment.

RESULTS

Osteoblastic reaction was detected in 10 cases (23%), showing different patterns: dimensional or density increase of known osteosclerotic metastases (pattern A, n = 4); response of previously lytic lesions (pattern B, n = 2); onset of new osteosclerotic lesions (pattern C, n = 4). Seven patients had partial response to TKI treatment, with response rate of 70%, vs 50% of patients with bone metastases without this reaction. No difference in terms of median overall survival or progression-free survival emerged between patients with or without osteoblastic reaction.

CONCLUSIONS

The correct clinico-radiologic interpretation of osteoblastic reaction is crucial to avoid waste of therapeutic lines when TKI treatment has not yet exhausted its potential effectiveness. Clinical implications of ambiguous radiologic findings as described in this study deserve further discussion.

Remarkable bone formation following gefitinib for extensive lytic bone metastasis: a report of two cases

Gefitinib inhibits the epidermal growth factor receptor tyrosine kinase and improves survival in patients with non-small-cell lung cancer. We report 2 patients with extensive lytic bony metastasis in the spine and pelvis secondary to advanced pulmonary adenocarcinoma who were treated with gefitinib and had remarkable bone formation in the lytic bone lesions in the spine and pelvis. Surgery for stabilisation was avoided.

Tumor-free osteosclerotic lesions in patients treated for metastatic melanoma using BRAF inhibitors

BRAF inhibitors (vemurafenib and dabrafenib) are commonly prescribed in BRAF-mutant metastatic melanoma and allow improvement of the overall survival and progression-free survival. They are, however, accompanied by many adverse effects which mainly affect the skin. We observed on computed tomographic scans in three different patients after 3 months of treatment, the onset of osteosclerotic lesions. In parallel, the computed tomographic scans showed a significant reduction in all of the previously identified metastases in all patients. The occurrence of such bone modifications under treatment was reported previously in others cancers, such as inoperable non-small-cell lung cancers under epidermal growth factor receptor inhibitors, as the 'osteoblastic bone flare phenomenon'. However, it had never been reported in melanoma patients treated with targeted therapies, and the results of two performed bone biopsies are reported here. This phenomenon is generally believed to indicate a better response under treatment, whereas in our study, the patients experienced, after a short partial response, a severe cerebral relapse leading to death. Finally, although its physiopathological mechanisms are poorly understood, the occurrence of tumor-free osteosclerotic lesions in patients under BRAF inhibitors should not be misinterpreted as a progression of the disease.

Identification of gefitinib off-targets using a structure-based systems biology approach; their validation with reverse docking and retrospective data mining

Gefitinib, an EGFR tyrosine kinase inhibitor, is used as FDA approved drug in breast cancer and non-small cell lung cancer treatment. However, this drug has certain side effects and complications for which the underlying molecular mechanisms are not well understood. By systems biology based in silico analysis, we identified off-targets of gefitinib that might explain side effects of this drugs. The crystal structure of EGFR-gefitinib complex was used for binding pocket similarity searches on a druggable proteome database (Sc-PDB) by using IsoMIF Finder. The top 128 hits of putative off-targets were validated by reverse docking approach. The results showed that identified off-targets have efficient binding with gefitinib. The identified human specific off-targets were confirmed and further analyzed for their links with biological process and clinical disease pathways using retrospective studies and literature mining, respectively. Noticeably, many of the identified off-targets in this study were reported in previous high-throughput screenings. Interestingly, the present study reveals that gefitinib may have positive effects in reducing brain and bone metastasis, and may be useful in defining novel gefitinib based treatment regime. We propose that a system wide approach could be useful during new drug development and to minimize side effect of the prospective drug.

Clinical Implications of Isolated Bone Failure Without Systemic Disease Progression During EGFR-TKI Treatment

BACKGROUND

We investigated the characteristics of patients with epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) who had experienced isolated progression of bone metastases without aggravation of extraskeletal organs during EGFR-tyrosine kinase inhibitor (TKI) treatment.

MATERIALS AND METHODS

We retrospectively reviewed the data from 870 patients with EGFR-mutant NSCLC treated with EGFR-TKI from 2004 to 2014. Of these patients, 71 (8.2%), who had undergone radiation therapy to bone metastases because of skeletal-related events, impending skeletal-related events, or medically uncontrolled bone pain, were selected and defined as having bone failure (BF). BFs were classified into 2 categories according to the presence of accompanying disease progression in extraskeletal organs: isolated BF (IBF) and non-IBF.

RESULTS

Of the 71 BF patients, 33 (46.5%) experienced IBF without aggravation of disease in extraskeletal organs. IBF was more frequent in the clinical benefit group (responders and stable for ≥ 6 months) than in nonclinical benefit group (54.4% vs. 14.3%; P = .007). IBF was also more frequent in those with good performance status (82.5% vs. 42.9%; P = .005) and 19 deletion (68.4% vs. 35.7%; P = .024). Female sex, good performance status, and clinical benefit from TKI were more frequent in patients with IBF than in those with non-IBF (female sex, 69.7% vs. 44.7%; P = .034; Eastern Cooperative Oncology Group 0 or 1, 87.9% vs. 63.2%; P = .017; clinical benefit from TKI, 93.9% vs. 68.4%; P = .007). Clinical benefit from EGFR-TKI was an independent predictor of IBF (adjusted odds ratio, 6.647; 95% confidence interval, 1.328-33.262; P = .021). Patients with IBF tended to exhibit longer survival times from the initiation of the TKI (20.7 vs. 11.1 months; P = .2) and from the onset of BF (8.6 vs. 3.4 months; P = .186).

CONCLUSION

IBF without systemic disease progression frequently occurs in patients with clinical benefits from EGFR-TKI and is associated with better survival. This finding requires future studies to explore the differential activity of EGFR-TKI in the bones over time or in preference to other organs.

The Modulatory Effects of Mesenchymal Stem Cells on Osteoclastogenesis

The effect of mesenchymal stem cells (MSCs) on bone formation has been extensively demonstrated through several in vitro and in vivo studies. However, few studies addressed the effect of MSCs on osteoclastogenesis and bone resorption. Under physiological conditions, MSCs support osteoclastogenesis through producing the main osteoclastogenic cytokines, RANKL and M-CSF. However, during inflammation, MSCs suppress osteoclast formation and activity, partly via secretion of the key anti-osteoclastogenic factor, osteoprotegerin (OPG). In vitro, co-culture of MSCs with osteoclasts in the presence of high concentrations of osteoclast-inducing factors might reflect the in vivo inflammatory pathology and prompt MSCs to exert an osteoclastogenic suppressive effect. MSCs thus seem to have a dual effect, by stimulating or inhibiting osteoclastogenesis, depending on the inflammatory milieu. This effect of MSCs on osteoclast formation seems to mirror the effect of MSCs on other immune cells, and may be exploited for the therapeutic potential of MSCs in bone loss associated inflammatory diseases.

RNA-seq analysis reveals significant effects of EGFR signalling on the secretome of mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (MSCs) contribute to breast cancer progression by releasing soluble factors that sustain tumor progression. MSCs express functional epidermal growth factor receptor (EGFR) and breast cancer cells secrete EGFR-ligands including transforming growth factor-α (TGFα). Using RNA-sequencing, we analysed the whole transcriptome of MSCs stimulated with TGFα. We identified 1,640 highly differentially regulated genes: 967 genes up-regulated with Fold Induction (FI)≥1.50 and 673 genes down-regulated with FI≤0.50. When highly regulated genes were categorized according to GO molecular function classification and KEGG pathways analysis, a large number of genes coding for potentially secreted proteins or surface receptors resulted enriched following TGFα treatment, including VEGFA, IL6, EREG, HB-EGF, LIF, NGF, NRG1, CCL19, CCL2, CCL25 and CXCL3. Secretion of corresponding proteins was confirmed for selected factors. Finally, we identified 4,377 and 4,262 alternatively spliced genes in untreated and TGFα-treated MSCs, respectively. Among these, an unannotated splice variant of VEGFA coding for a secreted VEGF protein of 172 aminoacids (VEGFA₁₇₂), was found only in MSCs stimulated with TGFα. These findings suggest that EGFR activation in MSCs leads to a significant change in the expression of a wide array of genes coding for secreted proteins that can significantly enhance tumor progression.

Bone Metastases and the EGFR and KRAS Mutation Status in Lung Adenocarcinoma--The Results of Three Year Retrospective Analysis

Lung cancer is a heterogeneous group of disease and mutational profiling of lung adenocarcinomas is a routine practice in thoracic oncology. Kirsten-RAS (KRAS) and EGFR mutations play an important role in the carcinogenesis of a subset of lung adenocarcinomas. Our aim was to investigate the correlation between bone metastases and EGFR and KRAS mutation status in lung adenocarcinoma patients. Retrospectively we analysed 224 patients with recurrent or metastatic lung adenocarcinomas. Patients were treated with standard chemotherapy as first line therapy and with EGFR-TK inhibitors as a second or third line therapy. 72 of 224 patients (32 %) had verified bone metastases. Bone metastases and Skeletal Related Events (SRE) were more frequent in men, heavy smokers and without treatment of EGFR TK inhibitors. We have found that EGFR and KRAS mutation status are both predictive factors for the treatment efficacy and prognostic factors for the disease progression. However there were no significant correlation between mutation status and the presence of bone metastases (P = 0, 59). In our study the presence of bone metastases proved to be an independent prognostic factor related to poor performance status and worse Quality of Life (QL).

Prostate cancer and bone: the elective affinities

The onset of metastases dramatically changes the prognosis of prostate cancer patients, determining increased morbidity and a drastic fall in survival expectancy. Bone is a common site of metastases in few types of cancer, and it represents the most frequent metastatic site in prostate cancer. Of note, the prevalence of tumor relapse to the bone appears to be increasing over the years, likely due to a longer overall survival of prostate cancer patients. Bone tropism represents an intriguing challenge for researchers also because the preference of prostate cancer cells for the bone is the result of a sequential series of targetable molecular events. Many factors have been associated with the peculiar ability of prostate cancer cells to migrate in bone marrow and to determine mixed osteoblastic/osteolytic lesions. As anticipated by the success of current targeted therapy aimed to block bone resorption, a better understanding of molecular affinity between prostate cancer and bone microenvironment will permit us to cure bone metastasis and to improve prognosis of prostate cancer patients.

Features and prognostic impact of distant metastasis in patients with stage IV lung adenocarcinoma harboring EGFR mutations: importance of bone metastasis

Mutated epidermal growth factor receptor (EGFR) and signaling pathways were associated with multiple brain and intra-pulmonary metastases, oncogenic progression and metastasis. However, features of metastasis to other organs and the independent prognostic influence of metastatic lesions were not elucidated in patients with lung cancer harboring EGFR mutations. Between January 2007 and April 2012, we treated 277 patients diagnosed with stage IV lung adenocarcinoma. Studied were 246 patients with available tumor EGFR mutation data who also underwent radiographic evaluation of lung, abdominal, brain, and bone metastases. The EGFR mutated group (N = 98) had significantly more metastatic lesions in the brain and bone than the wild-type group (N = 148): brain, 3 (1-93) versus 2 (1-32) median (range), P = 0.023; bone, 3 (1-43) versus 2 (1-27), P = 0.035, respectively. In addition, EGFR mutations were significantly more frequent in patients with multiple than non-multiple lung metastases (24/40 vs. 12/42, P = 0.004). Multivariate analysis showed that bone metastasis was a significant independent negative predictive factor of overall survival (OS) in patients with mutated [hazard ratio (HR) 2.04; 95 % confidence interval (CI) 1.17-3.64; P = 0.011] and wild-type EGFR (HR 2.09; 95 % CI 1.37-3.20; P < 0.001). In conclusion, patients with mutated EGFR had more lung, brain, and bone metastases, and bone metastasis was an independent negative predictor of OS.

A Case of Lung Adenocarcinoma with Postoperative Recurrence of Multiple Bone Metastases that Showed a Gradual Complete Response to Combined Administration of Erlotinib and Zoledronic Acid

We describe a case of lung adenocarcinoma with multiple postoperative bone metastases that showed a gradual but complete response to combined administration of erlotinib and zoledronic acid. A 76-year-old man with moderately differentiated adenocarcinoma underwent a radical left upper lobectomy and mediastinal lymph node dissection. Three and a half years after the operation, serum carcinoembryonic antigen (CEA) was elevated and 18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) revealed multiple bone metastases. Pretreatment evaluation of EGFR mutations in the resected primary adenocarcinoma specimen showed an L858R mutation in exon 21. Gefitinib was started as first-line treatment. However, evaluation 1 month after administration revealed progressive disease. Erlotinib was started as second-line treatment, and evaluation 1 month after administration revealed that the disease was stable. Administration of zoledronic acid was then begun with continuation of erlotinib. After 2 courses of zoledronic acid, the serum CEA level had not changed but the maximum standardized uptake values of each region uniformly decreased. Furthermore, the uptake of 18FDG completely disappeared after 6 courses. Subsequently, the serum CEA level continued to decrease and the disappearance of 18FDG uptake was confirmed after 10 courses (12 months after initiation of erlotinib administration). Our results suggest that the combined administration of both drugs is effective against bone metastases.

Targeting tumor-stromal interactions in bone metastasis

Bone metastasis is a frequent occurrence in late stage solid tumors, including breast cancers, prostate or lung. However, the causes for this proclivity have only recently been elucidated. Significant progress has been made in the past decade toward understanding the molecular underpinnings of bone metastasis, and much of this research reveals a crucial role of the host stroma in each step of the metastatic cascade. Tumor-stromal interactions are crucial in engineering a pre-metastatic niche, accommodating metastatic seeding, and establishing the vicious cycle of bone metastasis. Current treatments in bone metastasis focus on latter steps of the metastatic cascade, with most treatments targeting the process of bone remodeling; however, emerging research identifies many other candidates as promising targets. Host stromal cells including platelets and endothelial cells are important in the early steps of metastatic homing, attachment and extravasation while a variety of immune cells, parenchymal cells and mesenchymal cells of the bone marrow are important in the establishment of overt, immune-suppressed metastatic lesions. Many participants during these steps have been identified and functionally validated. Significant contributors include integrins, (αvβ3, α2β1, α4β1), TGFβ family members, bone resident proteins (BSP, OPG, SPARC, OPN), RANKL, and PTHrP. In this review, we will discuss the contribution of host stromal cells to pre-metastatic niche conditioning, seeding, dormancy, bone-remodeling, immune regulation, and chemotherapeutic shielding in bone metastasis. Research exploring these interactions between bone metastases and stromal cells has yielded many therapeutic targets, and we will discuss both the current and future therapeutic avenues in treating bone metastasis.

Gefitinib inhibits the cross-talk between mesenchymal stem cells and prostate cancer cells leading to tumor cell proliferation and inhibition of docetaxel activity

Increasing evidence suggests that bone marrow derived mesenchymal stem cells (BM-MSCs) are recruited into the stroma of developing tumors where they contribute to progression by enhancing tumor growth and metastasis, or by inducing anticancer-drug resistance. Prostate cancer cells secrete ligands of epidermal growth factor receptor (EGFR) and EGFR signaling could play an important role in the cross-talk between mesenchymal stem cells and prostate cancer cells. In this study, we showed that treatment of human primary MSCs with conditioned medium (CM) derived from the bone metastatic PC3 carcinoma cells (PC3-CM) resulted in: a significant activation of EGFR; increased proliferation; increased osteoblastic but decreased adipocitic differentiation; inhibition of senescence induced by serum starvation; increased CCL5 secretion. These activities were significantly inhibited in the presence of the EGFR tyrosine kinase inhibitor gefitinib. PC3-CM directly inhibited osteoclastogenesis as well as the ability of osteoblasts to induce osteoclast differentiation. The increased MSCs migration by PC3-CM and PC3 cells was partially mediated by CCL5. MSC-CM increased the formation of colonies by PC3 cells and inhibited the anti-proliferative activity of Docetaxel. Activation of EGFR expressed on MSCs by PC3-CM enhanced their capability to increase PC3 cells proliferation and to inhibit Docetaxel activity. These findings, by showing that the tumor-promoting interactions between PC3 cells and MSCs are mediated, at least in part, by EGFR, suggest a novel application of the EGFR-tyrosine kinase inhibitors in the treatment of prostate cancer.

RNA therapeutics targeting osteoclast-mediated excessive bone resorption

RNA interference (RNAi) is a sequence-specific post-transcriptional gene silencing technique developed with dramatically increasing utility for both scientific and therapeutic purposes. Short interfering RNA (siRNA) is currently exploited to regulate protein expression relevant to many therapeutic applications, and commonly used as a tool for elucidating disease-associated genes. Osteoporosis and their associated osteoporotic fragility fractures in both men and women are rapidly becoming a global healthcare crisis as average life expectancy increases worldwide. New therapeutics are needed for this increasing patient population. This review describes the diversity of molecular targets suitable for RNAi-based gene knock down in osteoclasts to control osteoclast-mediated excessive bone resorption. We identify strategies for developing targeted siRNA delivery and efficient gene silencing, and describe opportunities and challenges of introducing siRNA as a therapeutic approach to hard and connective tissue disorders.

At the crossroads: EGFR and PTHrP signaling in cancer-mediated diseases of bone

The epidermal growth factor receptor is a well-established cancer therapeutic target due to its stimulation of proliferation, motility, and resistance to apoptosis. Recently, additional roles for the receptor have been identified in growth of metastases. Similar to development, metastatic spread requires signaling interactions between epithelial-derived tumor cells and mesenchymal derivatives of the microenvironment. This necessitates reactivation of developmental signaling molecules, including the hypercalcemia factor parathyroid hormone-related protein. This review covers the variations of epidermal growth factor receptor signaling in cancers that produce bone metastases, regulation of parathyroid hormone-related protein, and evidence that the two molecules drive cancer-mediated diseases of bone.

Prognostic factors for non-small cell lung cancer with bone metastasis at the time of diagnosis

INTRODUCTION

The skeletal system is one of the most common distant sites of metastatic non-small cell lung cancer (NSCLC) which may lead to skeletal-related event (SRE). The purpose of this study was to assess the frequency of SRE and the prognostic factors of overall survival (OS) in patients presenting bone metastasis in NSCLC.

METHODS

Two hundred and twenty NSCLC patients with skeletal metastases at the time of diagnosis between January 2000 and August 2007 were investigated retrospectively.

RESULTS

Forty-seven of 110 patients (43%) without a SRE at the time of diagnosis experienced their first SRE during the follow-up. Patients with squamous cell carcinoma had a 1.8-times higher risk of short OS [95% confidence interval (CI) 1.11-2.84, p=0.016], compared with patients with non-squamous cell carcinoma, and patients treated with EGFR TKIs achieved a 50% protective effect in OS compared with patients not treated with them (95% CI 0.32-0.80, p=0.004). Patients with ECOG performance status 0-1 and single bone metastasis had a 1.8-times (95% CI 1.13-2.60, p=0.003) and 2.4-times (95% CI 1.26-4.46, p=0.008) longer OS than patients with performance status≥2 and two or more bone metastases, respectively.

CONCLUSION

Our study demonstrated that the frequency of SRE was common and single bone metastasis, good performance status (ECOG 0, 1), EGFR TKI treatment had good prognosis and histology of squamous cell carcinoma had bad prognosis.

Osteosclerotic lesions in patients treated with gefitinib for lung adenocarcinomas: a sign of favorable therapeutic response

OBJECTIVE

To assess the frequency of osteosclerotic changes on CT that appeared after treatment with gefitinib in patients with lung adenocarcinoma and the relationship between the osteosclerotic changes and the response to the therapy.

MATERIALS AND METHODS

Our study included 41 patients with lung adenocarcinoma who underwent chest CT both before (CTpre) and after (CTpost) starting treatment with gefitinib. The presence or absence of bone metastases was assessed on the CTpre, and the interval bony change after the therapy was classified as lytic, sclerotic, or no changes on the CTpost. The relationship between treatment results of primary lung cancer and interval bony changes was evaluated.

RESULTS

Osteosclerotic lesions were identified in 11 patients (27%) on CTpost; in 6 of 11 patients osteosclerotic lesions newly appeared where the CTpre showed no bone metastasis before the gefitinib therapy. There were significant differences in the therapeutic response of the primary cancers (P < 0.001) and in the survival rate (P < 0.01) in patients with osteosclerotic changes versus those without osteosclerotic changes.

CONCLUSION

Osteosclerotic changes on CT, observed after gefitinib treatment in patients with lung adenocarcinomas, may be an indicator of a good therapeutic response.

Zoledronic acid blocks the interaction between mesenchymal stem cells and breast cancer cells: implications for adjuvant therapy of breast cancer

BACKGROUND

Zoledronic acid (ZA) reduces locoregional and distant metastases in estrogen receptor (ER)-positive breast cancer patients. Since ZA rapidly concentrates in the bone following i.v. administration, we hypothesized that this phenomenon involves the mechanism of action of ZA in bone tissue.

MATERIALS AND METHODS

Migration assays were carried out in fibronectin-coated Boyden chambers. Activation of signaling proteins was analyzed with a phosphoprotein array. Chemokines and growth factors were measured by immunoassays and real-time PCR.

RESULTS

ZA significantly reduced in bone marrow-derived mesenchymal stem cells (MSCs) the activation of AKT and mitogen-activated protein kinase and their ability to migrate. Conditioned medium (CM) from ZA-treated MSCs showed a reduced capacity to promote the migration of ER-positive MCF-7 breast cancer cells as compared with CM from untreated MSCs. The levels of the chemokine (C-C motif) ligand 5 (CCL5, also known as RANTES - Regulated upon Activation, Normal T-cell Expressed, and Secreted) and interleukin (IL)-6 were significantly reduced in MSC-CM following treatment with ZA. Anti-RANTES and anti-IL-6 antibodies almost completely abolished the migration of MCF-7 cells induced by MSC-CM. Recombinant RANTES and IL-6 significantly induced MCF-7 cell migration and their combination showed a cooperative effect. Similar results were observed in different breast cancer cell lines.

CONCLUSION

ZA might exert its antitumor activity by inhibiting MSC migration and blocking MSCs' secretion of factors involved in breast cancer progression.

Epidermal growth factor receptor signalling contributes to osteoblastic stromal cell proliferation, osteoclastogenesis and disease progression in giant cell tumour of bone

AIMS

Epidermal growth factor receptor (EGFR) is implicated in bone remodelling. The aim was to determine whether EGFR protein expression contributes to the aggressiveness and recurrence potential of giant cell tumour of bone (GCTB), an osteolytic primary bone tumour that can exhibit markedly variable clinical behaviour.

METHODS AND RESULTS

Immunohistochemical analysis on tissue microarrays (TMA) of 231 primary, 97 recurrent, 17 metastatic and 26 malignant GCTBs was performed using TMA analysis software and whole digital slides allowing validated scoring. EGFR expression was restricted to neoplastic stromal cells and was significantly more frequent in recurrent (71 of 92; 77%) than in non-recurrent GCTBs (86 of 162; 53%) (P = 0.002); and in clinicoradiologically aggressive (31 of 43; 72%) than latent (27 of 54; 50%) cases (P = 0.034). Detecting phosphotyrosine epitopes pY1068 and -pY1173 indicated active EGFR signalling, and finding EGFR ligands EGF and transforming growth factor-α restricted to cells of the monocytic lineage suggested paracrine EGFR activation in stromal cells. In functional studies EGF supported proliferation of GCTB stromal cells, and the addition of EGF and macrophage-colony stimulating factor promoted osteoclastogenesis.

CONCLUSION

In GCTB, EGFR signalling in neoplastic stromal cells may contribute to disease progression through promoting stromal cell proliferation and osteoclastogenesis.

Erlotinib prevents experimental metastases of human small cell lung cancer cells with no epidermal growth factor receptor expression

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) show dramatic antitumor activity in a subset of patients with non-small cell lung cancer who have an active mutation in the epidermal growth factor receptor (EGFR) gene. On the other hand, some lung cancer patients with wild type EGFR also respond to EGFR-TKIs, suggesting that EGFR-TKIs have an effect on host cells as well as tumor cells. However, the effect of EGFR-TKIs on host microenvironments is largely unknown. A multiple organ metastasis model was previously established in natural killer cell-depleted severe combined immunodeficient mice using human lung cancer cells. This model was used to investigate the therapeutic efficacy of erlotinib, an EGFR-TKI, on multiple organ metastases induced by human small cell lung cancer cells (SBC-5 cells) that did not express EGFR. Although erlotinib did not have any effect on the proliferation of SBC-5 cells in vitro, it significantly suppressed bone and lung metastases in vivo, but not liver metastases. An immunohistochemical analysis revealed that, erlotinib significantly suppressed the number of osteoclasts in bone metastases, whereas no difference was seen in microvessel density. Moreover, erlotinib inhibited EGF-induced receptor activator of nuclear factor kappa-B expression in an osteoblastic cell line (MC3T3-E1 cells). These results strongly suggested that erlotinib prevented bone metastases by affecting host microenvironments irrespective of its direct effect on tumor cells.

Role of the EGFR ligand/receptor system in the secretion of angiogenic factors in mesenchymal stem cells

Increasing evidence suggests that bone marrow-derived mesenchymal stem cells (MSCs) are recruited into the stroma of developing tumors where they contribute to cancer progression. MSCs produce different growth factors that sustain tumor-associated neo-angiogenesis. Since the majority of carcinomas secrete ligands of the epidermal growth factor receptor (EGFR), we assessed the role of EGFR signaling in regulating the release of angiogenic factors in MSCs. Treatment of human primary MSCs and of the human osteoblastic cell line hFOB with transforming growth factor α (TGF-α), one of the main ligands of the EGFR, significantly induced activation of this receptor and of different intracellular signaling proteins, including the PI3K/AKT and the MEK/MAPK pathways. TGF-α induced a significant increase in the levels of secretion of vascular endothelial growth factor in both MSCs and hFOB. Conditioned medium from TGF-α treated MSCs showed an higher in vivo angiogenic effect as compared with medium from untreated cells. Treatment of MSCs with TGF-α also produced a significant increase in the secretion of other angiogenic growth factors such as angiopoietin-2, granulocyte-colony stimulating factor, hepatocyte growth factor, interleukin (IL)-6, IL-8, and platelet-derived growth factor-BB. Using selective MEK and PI3K inhibitors, we found that both MEK/MAPK and the PI3K/AKT signaling pathways mediate the ability of TGF-α to induce secretion of angiogenic factors in MSCs. Finally, stimulation with TGF-α increased the ability of MSCs to induce migration of MCF-7 breast cancer cells. These data suggest that EGFR signaling regulates the ability of MSCs to sustain cancer progression through the release of growth factors that promote neo-angiogenesis and tumor cell migration.

Erlotinib inhibits osteolytic bone invasion of human non-small-cell lung cancer cell line NCI-H292

Previous preclinical and clinical findings have suggested a potential role of epidermal growth factor receptor (EGFR) in osteoclast differentiation and the pathogenesis of bone metastasis in cancer. In this study, we investigated the effect of erlotinib, an orally active EGFR tyrosine kinase inhibitor (TKI), on the bone invasion of human non-small-cell lung cancer (NSCLC) cell line NCI-H292. First, we established a novel osteolytic bone invasion model of NCI-H292 cells which was made by inoculating cancer cells into the tibia of scid mice. In this model, NCI-H292 cells markedly activated osteoclasts in tibia, which resulted in osteolytic bone destruction. Erlotinib treatment suppressed osteoclast activation to the basal level through suppressing receptor activator of NF-κB ligand (RANKL) expression in osteoblast/stromal cell at the bone metastatic sites, which leads to inhibition of osteolytic bone destruction caused by NCI-H292 cells. Erlotinib inhibited the proliferation of NCI-H292 cells in in vitro. Erlotinib suppressed the production of osteolytic factors, such as parathyroid hormone-related protein (PTHrP), IL-8, IL-11 and vascular endothelial growth factor (VEGF) in NCI-H292 cells. Furthermore, erlotinib also inhibited osteoblast/stromal cell proliferation in vitro and the development of osteoclasts induced by RANKL in vitro. In conclusion, erlotinib inhibits tumor-induced osteolytic invasion in bone metastasis by suppressing osteoclast activation through inhibiting tumor growth at the bone metastatic sites, osteolytic factor production in tumor cells, osteoblast/stromal cell proliferation and osteoclast differentiation from mouse bone marrow cells.

Epidermal growth factor receptor plays an anabolic role in bone metabolism in vivo

While the epidermal growth factor receptor (EGFR)-mediated signaling pathway has been shown to have vital roles in many developmental and pathologic processes, its functions in the development and homeostasis of the skeletal system has been poorly defined. To address its in vivo role, we constructed transgenic and pharmacologic mouse models and used peripheral quantitative computed tomography (pQCT), micro-computed tomography (µCT) and histomorphometry to analyze their trabecular and cortical bone phenotypes. We initially deleted the EGFR in preosteoblasts/osteoblasts using a Cre/loxP system (Col-Cre Egfr(f/f)), but no bone phenotype was observed because of incomplete deletion of the Egfr genomic locus. To further reduce the remaining osteoblastic EGFR activity, we introduced an EGFR dominant-negative allele, Wa5, and generated Col-Cre Egfr(Wa5/f) mice. At 3 and 7 months of age, both male and female mice exhibited a remarkable decrease in tibial trabecular bone mass with abnormalities in trabecular number and thickness. Histologic analyses revealed decreases in osteoblast number and mineralization activity and an increase in osteoclast number. Significant increases in trabecular pattern factor and structural model index indicate that trabecular microarchitecture was altered. The femurs of these mice were shorter and smaller with reduced cortical area and periosteal perimeter. Moreover, colony-forming unit-fibroblast (CFU-F) assay indicates that these mice had fewer bone marrow mesenchymal stem cells and committed progenitors. Similarly, administration of an EGFR inhibitor into wild-type mice caused a significant reduction in trabecular bone volume. In contrast, Egfr(Dsk5/+) mice with a constitutively active EGFR allele displayed increases in trabecular and cortical bone content. Taken together, these data demonstrate that the EGFR signaling pathway is an important bone regulator and that it primarily plays an anabolic role in bone metabolism.

Differential proteome analysis of bone marrow mesenchymal stem cells from adolescent idiopathic scoliosis patients

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional deformity of the spine. The cause and pathogenesis of scoliosis and the accompanying generalized osteopenia remain unclear despite decades of extensive research. In this study, we utilized two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry (MS) to analyze the differential proteome of bone marrow mesenchymal stem cells (BM-MSCs) from AIS patients. In total, 41 significantly altered protein spots were detected, of which 34 spots were identified by MALDI-TOF/TOF analysis and found to represent 25 distinct gene products. Among these proteins, five related to bone growth and development, including pyruvate kinase M2, annexin A2, heat shock 27 kDa protein, γ-actin, and β-actin, were found to be dysregulated and therefore selected for further validation by Western blot analysis. At the protein level, our results supported the previous hypothesis that decreased osteogenic differentiation ability of MSCs is one of the mechanisms leading to osteopenia in AIS. In summary, we analyzed the differential BM-MSCs proteome of AIS patients for the first time, which may help to elucidate the underlying molecular mechanisms of bone loss in AIS and also increase understanding of the etiology and pathogenesis of AIS.

Optimizing response to gefitinib in the treatment of non-small-cell lung cancer

The epidermal growth factor receptor (EGFR) is expressed in the majority of non-small-cell lung cancer (NSCLC). However, only a restricted subgroup of NSCLC patients respond to treatment with the EGFR tyrosine kinase inhibitor (EGFR TKI) gefitinib. Clinical trials have demonstrated that patients carrying activating mutations of the EGFR significantly benefit from treatment with gefitinib. In particular, mutations of the EGFR TK domain have been shown to increase the sensitivity of the EGFR to exogenous growth factors and, at the same time, to EGFR TKIs such as gefitinib. EGFR mutations are more frequent in patients with particular clinical and pathological features such as female sex, nonsmoker status, adenocarcinoma histology, and East Asian ethnicity. A close correlation was found between EGFR mutations and response to gefitinib in NSCLC patients. More importantly, randomized Phase III studies have shown the superiority of gefitinib compared with chemotherapy in EGFR mutant patients in the first-line setting. In addition, gefitinib showed a good toxicity profile with an incidence of adverse events that was significantly lower compared with chemotherapy. Therefore, gefitinib is a major breakthrough for the management of EGFR mutant NSCLC patients and represents the first step toward personalized treatment of NSCLC.

EGFR signaling in breast cancer: bad to the bone

The epidermal growth factor receptor (EGFR) is a member of the ErbB family of receptor tyrosine kinases. This family includes EGFR/ErbB1/HER1, ErbB2/HER2/Neu ErbB3/HER3, and ErbB4/HER4. For many years it was believed that EGFR plays a minor role in the development and progression of breast malignancies. However, recent findings have led investigators to revisit these beliefs. Here we will review these findings and propose roles that EGFR may play in breast malignancies. In particular, we will discuss the potential roles that EGFR may play in triple-negative tumors, resistance to endocrine therapies, maintenance of stem-like tumor cells, and bone metastasis. Thus, we will propose the contexts in which EGFR may be a therapeutic target.

EGFR signaling in breast cancer: bad to the bone

The epidermal growth factor receptor (EGFR) is a member of the ErbB family of receptor tyrosine kinases. This family includes EGFR/ErbB1/HER1, ErbB2/HER2/Neu ErbB3/HER3, and ErbB4/HER4. For many years it was believed that EGFR plays a minor role in the development and progression of breast malignancies. However, recent findings have led investigators to revisit these beliefs. Here we will review these findings and propose roles that EGFR may play in breast malignancies. In particular, we will discuss the potential roles that EGFR may play in triple-negative tumors, resistance to endocrine therapies, maintenance of stem-like tumor cells, and bone metastasis. Thus, we will propose the contexts in which EGFR may be a therapeutic target.

Osteoblastic reaction in non-small cell lung carcinoma and its association to epidermal growth factor receptor tyrosine kinase inhibitors response and prolonged survival

INTRODUCTION

The aim of this study was to describe the characteristics and epidermal growth factor receptor (EGFR) mutational status of patients with non-small cell lung cancer (NSCLC) with osteoblastic reactions diagnosed before or during treatment with EGFR tyrosine kinase inhibitors (TKIs).

METHODS

Retrospective study including patients with 36 NSCLC with at least one site of osteoblastic reaction at the time of diagnosis or during treatment with EGFR-TKI.

RESULTS

The rate of patients with mutated EGFR tumors with osteoblastic reactions before or after EGFR-TKI treatment was similar. Median progression-free survival (PFS) for the entire group was more than 9 months and median survival was more than 12 months. There was no statistically significant difference in survival between patients with osteoblastic reactions before initiation of TKI and those diagnosed during TKI treatment. Patients with extraosseous metastases when treated with TKI had the lowest survival (P < 0.0001).

CONCLUSIONS

In patients with NSCLC treated with TKI, initial or development of an osteoblastic reaction seems to be related to a more favorable outcome. In patients with osteoblastic reactions, tumors present with clinical and biologic characteristics of better survival and response to TKI. The occurrence of osteoblastic reactions during treatment with TKI, while primary tumor and metastases are stable or in response, should not be considered as disease progression.