Transit Time Measurement in Indicator Dilution Curves: Overcoming the Missing Ground Truth and Quantifying the Error.

The vascular function of a vessel can be qualitatively and intraoperatively checked by recording the blood dynamics inside the vessel via fluorescence angiography (FA). Although FA is the state of the art in proving the existence of blood flow during interventions such as bypass surgery, it still lacks a quantitative blood flow measurement that could decrease the recurrence rate and postsurgical mortality. Previous approaches show that the measured flow has a significant deviation compared to the gold standard reference (ultrasonic flow meter). In order to systematically address the possible sources of error, we investigated the error in transit time measurement of an indicator. Obtaining in vivo indicator dilution curves with a known ground truth is complex and often not possible. Further, the error in transit time measurement should be quantified and reduced. To tackle both issues, we first computed many diverse indicator dilution curves using an in silico simulation of the indicator's flow. Second, we post-processed these curves to mimic measured signals. Finally, we fitted mathematical models (parabola, gamma variate, local density random walk, and mono-exponential model) to re-continualize the obtained discrete indicator dilution curves and calculate the time delay of two analytical functions. This re-continualization showed an increase in the temporal accuracy up to a sub-sample accuracy. Thereby, the Local Density Random Walk (LDRW) model performed best using the cross-correlation of the first derivative of both indicator curves with a cutting of the data at 40% of the peak intensity. The error in frames depends on the noise level and is for a signal-to-noise ratio (SNR) of 20 dB and a sampling rate of f s = 60 Hz at f s - 1 · 0 . 25 ( ± 0 . 18 ) , so this error is smaller than the distance between two consecutive samples. The accurate determination of the transit time and the quantification of the error allow the calculation of the error propagation onto the flow measurement. Both can assist surgeons as an intraoperative quality check and thereby reduce the recurrence rate and post-surgical mortality.

In vivo optoacoustic monitoring of percutaneous laser ablation of tumors in a murine breast cancer model.

Laser ablation (LA) is a promising approach for minimally invasive cancer treatments. Its in vivo applicability is often impeded by the lack of efficient monitoring tools that can help to minimize collateral tissue damage and aid in determining the optimal treatment end-points. We have devised a new, to the best of our knowledge, hybrid LA approach combining simultaneous volumetric optoacoustic (OA) imaging to monitor the lesion progression accurately in real time and 3D. Time-lapse imaging of laser ablation of solid tumors was performed in a murine breast cancer model in vivo by irradiation of subcutaneous tumors with a 100 mJ short-pulsed (${\sim}{5}\;{\rm ns}$∼5ns) laser operating at 1064 nm and 100 Hz pulse repetition frequency. Local changes in the OA signal intensity ascribed to structural alterations in the tumor vasculature were clearly observed, while the OA volumetric projections recorded in vivo appeared to correlate with cross sections of the excised tumors.

Hoarseness ­ causes and treatments. / Heiserkeit Ursachen und Therapie.

Due to a hoarseness or dysphonia about 1 % of patients consult a doctor. The causes of hoarseness are very diverse and can range from a harmless laryngitis to vocal cord tumors. In addition to acute and chronic laryngitis (42 % and 10 %), functional dysphonia (30 %), benign (15 %) and malignant tumors (3 %), vocal cord paresis (5 %), the physiological aging voice (2 %) and psychogenic factors (2 %) can cause hoarseness. The manifestation of internal diseases is very rare. Treatment options depending on the cause are drugs, voice therapy or surgery. The present article gives an overview of possible causes of hoarseness, diagnosis and treatment options. Hoarseness lasting more than three weeks should always be taken seriously and be examined laryngoscopically.

Phase I study of GC1008 (fresolimumab): a human anti-transforming growth factor-beta (TGFß) monoclonal antibody in patients with advanced malignant melanoma or renal cell carcinoma.

BACKGROUND: In advanced cancers, transforming growth factor-beta (TGFß) promotes tumor growth and metastases and suppresses host antitumor immunity. GC1008 is a human anti-TGFß monoclonal antibody that neutralizes all isoforms of TGFß. Here, the safety and activity of GC1008 was evaluated in patients with advanced malignant melanoma and renal cell carcinoma. METHODS: In this multi-center phase I trial, cohorts of patients with previously treated malignant melanoma or renal cell carcinoma received intravenous GC1008 at 0.1, 0.3, 1, 3, 10, or 15 mg/kg on days 0, 28, 42, and 56. Patients achieving at least stable disease were eligible to receive Extended Treatment consisting of 4 doses of GC1008 every 2 weeks for up to 2 additional courses. Pharmacokinetic and exploratory biomarker assessments were performed. RESULTS: Twenty-nine patients, 28 with malignant melanoma and 1 with renal cell carcinoma, were enrolled and treated, 22 in the dose-escalation part and 7 in a safety cohort expansion. No dose-limiting toxicity was observed, and the maximum dose, 15 mg/kg, was determined to be safe. The development of reversible cutaneous keratoacanthomas/squamous-cell carcinomas (4 patients) and hyperkeratosis was the major adverse event observed. One malignant melanoma patient achieved a partial response, and six had stable disease with a median progression-free survival of 24 weeks for these 7 patients (range, 16.4-44.4 weeks). CONCLUSIONS: GC1008 had no dose-limiting toxicity up to 15 mg/kg. In patients with advanced malignant melanoma and renal cell carcinoma, multiple doses of GC1008 demonstrated acceptable safety and preliminary evidence of antitumor activity, warranting further studies of single agent and combination treatments. TRIAL REGISTRATION: Clinicaltrials.gov NCT00356460.

Alterations of Smad expression and activation in defining 2 subtypes of human head and neck squamous cell carcinoma.

BACKGROUND: We postulated that disruptions of the canonical transforming growth factor-beta (TGF-ß)/Smad signaling pathway might contribute to the development of head and neck squamous cell carcinoma (HNSCC). METHODS: A cohort of 798 HNSCC tumor samples from 346 patients were analyzed by immunohistochemistry (IHC) to define the pattern of expression of (phospho)Smad2, (phospho)Smad3, and Smad4. RESULTS: We found that 19%, 40%, and 12% of HNSCC specimens failed to express pSmad2, pSmad3, or Smad4, respectively. Loss of Smad2/3 activation was observed in 8.5% of specimens. In addition, 4% of specimens failed to express only Smad4. Moreover, patients with pSmad2/3-negative tumors had a significantly better overall survival than that of those whose tumors expressed activated Smad2/3. In contrast, loss of Smad4 expression did not have prognostic significance. CONCLUSION: Our results indicate that HNSCC in which Smad2/3 are inactivated or in which Smad4 expression is lost represent 2 distinct tumor subtypes with different clinical outcomes.

Transforming growth factor (TGF)-ß expression and activation mechanisms as potential targets for anti-tumor therapy and tumor imaging.

Cancer remains one of the leading causes of death in the developed countries and cancer mortality is expected to rise globally. Despite encouraging developments regarding targeted drugs, the most prevalent cancer mortality remains metastatic disease. Therefore, drugs that target cancer progression, invasion and metastasis are clearly needed. One of the most interesting targets in this setting is transforming growth factor ß (TGF-ß). TGF-ß can promote tumor growth, invasion and metastasis. However, TGF-ß also has a physiological, opposing role: maintaining tissue homeostasis and suppression of tumor progression. The window of effective TGF-ß targeting is therefore evidently small, which poses a clear challenge in selecting patients at the right time. Despite this complexity, several TGF-ß inhibitors are currently in clinical development, modulating TGF-ß production, activation or signaling. Still, specificity and long term toxicity remain unclear, emphasizing the importance of careful monitoring of clinical trials. Development and application of these drugs in the clinic require adequate insight and evaluation methods for the role of TGF-ß during tumor invasion and metastasis. In this review, presently available methods for clinical evaluation will be discussed, such as an ex vivo stimulation assay, TGF-ß response signature and molecular imaging techniques. Future clinical trials incorporating the validation of these evaluation methods will show which method will be most predictive and suitable for clinical application.

Identification of function for CD44 intracytoplasmic domain (CD44-ICD): modulation of matrix metalloproteinase 9 (MMP-9) transcription via novel promoter response element.

CD44 is a multifunctional cell receptor that conveys a cancer phenotype, regulates macrophage inflammatory gene expression and vascular gene activation in proatherogenic environments, and is also a marker of many cancer stem cells. CD44 undergoes sequential proteolytic cleavages that produce an intracytoplasmic domain called CD44-ICD. However, the role of CD44-ICD in cell function is unknown. We take a major step toward the elucidation of the CD44-ICD function by using a CD44-ICD-specific antibody, a modification of a ChIP assay to detect small molecules, and extensive computational analysis. We show that CD44-ICD translocates into the nucleus, where it then binds to a novel DNA consensus sequence in the promoter region of the MMP-9 gene to regulate its expression. We also show that the expression of many other genes that contain this novel response element in their promoters is up- or down-regulated by CD44-ICD. Furthermore, hypoxia-inducible factor-1α (Hif1α)-responsive genes also have the CD44-ICD consensus sequence and respond to CD44-ICD induction under normoxic conditions and therefore independent of Hif1α expression. Additionally, CD44-ICD early responsive genes encode for critical enzymes in the glycolytic pathway, revealing how CD44 could be a gatekeeper of the Warburg effect (aerobic glycolysis) in cancer cells and possibly cancer stem cells. The link of CD44 to metabolism is novel and opens a new area of research not previously considered, particularly in the study of obesity and cancer. In summary, our results finally give a function to the CD44-ICD and will accelerate the study of the regulation of many CD44-dependent genes.

Luminal breast cancer metastasis is dependent on estrogen signaling.

Luminal breast cancer is the most frequently encountered type of human breast cancer and accounts for half of all breast cancer deaths due to metastatic disease. We have developed new in vivo models of disseminated human luminal breast cancer that closely mimic the human disease. From initial lesions in the tibia, locoregional metastases develop predictably along the iliac and retroperitoneal lymph node chains. Tumors cells retain their epithelioid phenotype throughout the process of dissemination. In addition, systemically injected metastatic MCF-7 cells consistently give rise to metastases in the skeleton, floor of mouth, adrenal glands, as well as in the lungs, liver, brain and mammary fat pad. We show that growth of luminal breast cancer metastases is highly dependent on estrogen in a dose-dependent manner and that estrogen withdrawal induces rapid growth arrest of metastatic disease. On the other hand, even though micrometastases at secondary sites remain viable in the absence of estrogen, they are dormant and do not progress to macrometastases. Thus, homing to and seeding of secondary sites do not require estrogen. Moreover, in sharp contrast to basal-like breast cancer metastasis in which transforming growth factor-ß signaling plays a key role, luminal breast cancer metastasis is independent of this cytokine. These findings have important implications for the development of targeted anti-metastatic therapy for luminal breast cancer.

[Conservative therapy of chronic sinusitis]. / Therapie der chronischen Rhinosinusitis.

The chronic rhinosinusitis is defined as chronic inflammation of the nose and nasal sinuses, with or without nasal polyps. Patients suffering from chronic rhinosinusitis report about nasal obstruction and secretion, olfactory impairment, head and facial pain. These symptoms cause also considerable impact on quality of life. Therefore, an adequate rhinological diagnostics as well as therapies are essential. This paper reviews the pharmacologic and non-pharmacologic therapy of chronic rhinosinusitis. First choice of therapy should be topical glucocorticoids. The application of glucocorticoids causes anti-inflammatory and certain curative effects. Hypertonic salt solutions improve nasal symptoms. Long-term therapy with oral macrolides might improve median to severe symptoms of chronic rhinosinusitis without nasal polyps. An additional therapy with antihistamines is possible in patients with an allergy. Adaptive desensitization in patients suffering from analgesic-intolerance associating among other with nasal polyps is currently the single causal therapy. Therefore, frequency of endonasal revision surgery is reduced after desensitization.

Epistaxis: some aspects of laterality in 326 patients.

Lateralization of primary epistaxis was prospectively studied in 326 patients at Radebeul Elblandklinikum. The male-female-ratio was 1.3:1. A slight dominance of the right side (45% right vs. 39% left) was found in all patients. Further analyzed were the relationship to the localization of bleeding (anterior or posterior), the age and possible causes or risk factors. Nose bleeding from the posterior nasal portion appears to be statistically significantly higher than on both sides of anterior epistaxis. No statistically significant age dependence of laterality of epistaxis was observed in the age groups which we selected. However, nosebleed appears more frequently in women under the age of 50 years in both nostrils. With identified risk factors, idiopathic epistaxis occurs more frequently on the right side than does nosebleed. Mechanical trauma (intranasal sprays or nose picking) is a possible factor explaining the dominance of epistaxis on the right side, especially in idiopathic cases.

Vestibular neuritis: is there any evidence of an asymmetric distribution?

Statistics in the literature showed that neuro-otological diseases (i.e. sudden hearing loss or tinnitus) occur predominantly in the left ear. In a seven-study meta-analysis of patients suffering from vestibular neuritis, Reiß found no clear dominance of one side (50.8% on the right side, 48.4% on the left side and 0.8% on both sides). The purpose of this study is to investigate the laterality of vestibular neuritis in a distinct population of patients. Lateralization of vestibular neuritis was studied in 160 patients treated at Elblandklinikum Radebeul from January 2004 to December 2009. There was a statistically non-significant dominance of the right side in the total sample, specifically in female patients (57% right vs. 40% left), but not in male patients. The study confirms the results of the meta-analysis: that there is no relevant side dominance in patients suffering from vestibular neuritis. In addition to the caloric test, the head impulse test was performed in 157 patients. In 92% of these patients, the disturbance of vestibular function could be confirmed with the head impulse test. This test is altogether a clinically useful instrument especially for follow-up, but also for diagnosis.

PET with the 89Zr-labeled transforming growth factor-ß antibody fresolimumab in tumor models.

UNLABELLED: Transforming growth factor-ß (TGF-ß) promotes cancer invasion and metastasis and is therefore a potential drug target for cancer treatment. Fresolimumab, which neutralizes all mammalian active isoforms of TGF-ß, was radiolabeled with (89)Zr for PET to analyze TGF-ß expression, antibody tumor uptake, and organ distribution. METHODS: (89)Zr was conjugated to fresolimumab using the chelator N-succinyldesferrioxamine-B-tetrafluorphenol. (89)Zr-fresolimumab was analyzed for conjugation ratio, aggregation, radiochemical purity, stability, and immunoreactivity. (89)Zr-fresolimumab tumor uptake and organ distribution were assessed using 3 protein doses (10, 50, and 100 µg) and compared with (111)In-IgG in a human TGF-ß-transfected Chinese hamster ovary xenograft model, human breast cancer MDA-MB-231 xenograft, and metastatic model. Latent and active TGF-ß1 expression was analyzed in tissue homogenates with enzyme-linked immunosorbent assay. RESULTS: (89)Zr was labeled to fresolimumab with high specific activity (>1 GBq/mg), high yield, and high purity. In vitro validation of (89)Zr-fresolimumab showed a fully preserved immunoreactivity and long (>1 wk) stability in solution and in human serum. In vivo validation showed an (89)Zr-fresolimumab distribution similar to IgG in most organs, except for a higher uptake in the liver in all mice and higher kidney uptake in the 10-µg group. (89)Zr-fresolimumab induced no toxicity in mice; it accumulated in primary tumors and metastases in a manner similar to IgG. Both latent and active TGF-ß was detected in tumor homogenates, whereas only latent TGF-ß could be detected in liver homogenates. Remarkably high (89)Zr-fresolimumab uptake was seen in sites of tumor ulceration and in scar tissue, processes in which TGF-ß is known to be highly active. CONCLUSION: Fresolimumab tumor uptake and organ distribution can be visualized and quantified with (89)Zr-fresolimumab PET. This technique will be used to guide further clinical development of fresolimumab and could possibly identify patients most likely to benefit.

Height of right and left ethmoid roofs: aspects of laterality in 644 patients.

Objective. The goal of the study was to determine the asymmetric distribution of the height of the ethmoid roof (fovea ethmoidalis). Method. We retrospectively reviewed 644 coronal sinus computer tomography (CT) scans. The height of the ethmoid roof was examined for possible lateral differences between the right and left sides. Results. In 221 CT scans (31%), there was an asymmetry between the height of the fovea ethmoidalis on the right and left side. Of these 221, 160 (72.4%) were lower on the right side, whereas 61 (27.6%) were lower on the left. The height of the ethmoid roof of the remaining 433 patients (66%) was symmetric. There were statistically significantly more asymmetric cases in men than in women (38% versus 29%). Conclusions. The present paper underlines the asymmetry, variability of the ethmoid roof, and the possible practical implications arising from that fact. The asymmetry of the roof of one side presents an additional point of consideration for careful preoperative and perioperative review of paranasal sinus CT scans in patients undergoing endonasal sinus surgery.

ImageMiner: a software system for comparative analysis of tissue microarrays using content-based image retrieval, high-performance computing, and grid technology.

OBJECTIVE AND DESIGN: The design and implementation of ImageMiner, a software platform for performing comparative analysis of expression patterns in imaged microscopy specimens such as tissue microarrays (TMAs), is described. ImageMiner is a federated system of services that provides a reliable set of analytical and data management capabilities for investigative research applications in pathology. It provides a library of image processing methods, including automated registration, segmentation, feature extraction, and classification, all of which have been tailored, in these studies, to support TMA analysis. The system is designed to leverage high-performance computing machines so that investigators can rapidly analyze large ensembles of imaged TMA specimens. To support deployment in collaborative, multi-institutional projects, ImageMiner features grid-enabled, service-based components so that multiple instances of ImageMiner can be accessed remotely and federated. RESULTS: The experimental evaluation shows that: (1) ImageMiner is able to support reliable detection and feature extraction of tumor regions within imaged tissues; (2) images and analysis results managed in ImageMiner can be searched for and retrieved on the basis of image-based features, classification information, and any correlated clinical data, including any metadata that have been generated to describe the specified tissue and TMA; and (3) the system is able to reduce computation time of analyses by exploiting computing clusters, which facilitates analysis of larger sets of tissue samples.

Use of the ODD-luciferase transgene for the non-invasive imaging of spontaneous tumors in mice.

BACKGROUND: In humans, imaging of tumors provides rapid, accurate assessment of tumor growth and location. In laboratory animals, however, the imaging of spontaneously occurring tumors continues to pose many technical and logistical problems. Recently a mouse model was generated in which a chimeric protein consisting of HIF-1α oxygen-dependent degradation domain (ODD) fused to luciferase was ubiquitously expressed in all tissues. Hypoxic stress leads to the accumulation of ODD-luciferase in the tissues of this mouse model which can be identified by non-invasive bioluminescence measurement. Since solid tumors often contain hypoxic regions, we performed proof-of-principle experiments testing whether this transgenic mouse model may be used as a universal platform for non-invasive imaging analysis of spontaneous solid tumors. METHODS AND MATERIALS: ODD-luciferase transgenic mice were bred with MMTV-neu/beclin1+/- mice. Upon injection of luciferin, bioluminescent background of normal tissues in the transgenic mice and bioluminescent signals from spontaneously mammary carcinomas were measured non-invasively with an IVIS Spectrum imaging station. Tumor volumes were measured manually and the histology of tumor tissues was analyzed. CONCLUSION: Our results show that spontaneous mammary tumors in ODD-luciferase transgenic mice generate substantial bioluminescent signals, which are clearly discernable from background tissue luminescence. Moreover, we demonstrate a strong quantitative correlation between the bioluminescent tumor contour and the volume of palpable tumors. We further demonstrate that shrinkage of the volume of spontaneous tumors in response to chemotherapeutic treatment can be determined quantitatively using this system. Finally, we show that the growth and development of spontaneous tumors can be monitored longitudinally over several weeks. Thus, our results suggest that this model could potentially provide a practical, reliable, and cost-effective non-invasive quantitative method for imaging spontaneous solid tumors in mice.

Constitutive Smad linker phosphorylation in melanoma: a mechanism of resistance to transforming growth factor-ß-mediated growth inhibition.

Melanoma cells are resistant to transforming growth factor-ß (TGFß)-induced cell-cycle arrest. In this study, we investigated a mechanism of resistance involving a regulatory domain, called linker region, in Smad2 and Smad3, main downstream effectors of TGFß. Melanoma cells in culture and tumor samples exhibited constitutive Smad2 and Smad3 linker phosphorylation. Treatment of melanoma cells with the MEK1/2 inhibitor, U0126, or the two pan-CDK and GSK3 inhibitors, Flavopiridol and R547, resulted in decreased linker phosphorylation of Smad2 and Smad3. Overexpression of the linker phosphorylation-resistant Smad3 EPSM mutant in melanoma cells resulted in an increase in expression of p15(INK4B) and p21(WAF1) , as compared with cells transfected with wild-type (WT) Smad3. In addition, the cell numbers of EPSM Smad3-expressing melanoma cells were significantly reduced compared with WT Smad3-expressing cells. These results suggest that the linker phosphorylation of Smad3 contributes to the resistance of melanoma cells to TGFß-mediated growth inhibition.

Targeting the Transforming Growth Factor-beta pathway inhibits human basal-like breast cancer metastasis.

BACKGROUND: Transforming Growth Factor beta (TGF-beta) plays an important role in tumor invasion and metastasis. We set out to investigate the possible clinical utility of TGF-beta antagonists in a human metastatic basal-like breast cancer model. We examined the effects of two types of the TGF-beta pathway antagonists (1D11, a mouse monoclonal pan-TGF-beta neutralizing antibody and LY2109761, a chemical inhibitor of TGF-beta type I and II receptor kinases) on sublines of basal cell-like MDA-MB-231 human breast carcinoma cells that preferentially metastasize to lungs (4175TR, 4173) or bones (SCP2TR, SCP25TR, 2860TR, 3847TR). RESULTS: Both 1D11 and LY2109761 effectively blocked TGF-beta-induced phosphorylation of receptor-associated Smads in all MDA-MB-231 subclones in vitro. Moreover, both antagonists inhibited TGF-beta stimulated in vitro migration and invasiveness of MDA-MB-231 subclones, indicating that these processes are partly driven by TGF-beta. In addition, both antagonists significantly reduced the metastatic burden to either lungs or bones in vivo, seemingly independently of intrinsic differences between the individual tumor cell clones. Besides inhibiting metastasis in a tumor cell autonomous manner, the TGF-beta antagonists inhibited angiogenesis associated with lung metastases and osteoclast number and activity associated with lytic bone metastases. In aggregate, these studies support the notion that TGF-beta plays an important role in both bone-and lung metastases of basal-like breast cancer, and that inhibiting TGF-beta signaling results in a therapeutic effect independently of the tissue-tropism of the metastatic cells. Targeting the TGF-beta pathway holds promise as a novel therapeutic approach for metastatic basal-like breast cancer. CONCLUSIONS: In aggregate, these studies support the notion that TGF-beta plays an important role in both bone-and lung metastases of basal-like breast cancer, and that inhibiting TGF-beta signaling results in a therapeutic effect independently of the tissue-tropism of the metastatic cells. Targeting the TGF-beta pathway holds promise as a novel therapeutic approach for metastatic basal-like breast cancer.

[Suppurative chronic otitis media: etiology, diagnosis and therapy]. / Die chronische eitrige Otitis: Ursachen, Diagnostik und Therapie.

The chronic otitis media is defined as a permanent perforation of the drum membrane, which does not close by itself, and an inflammatory reaction in the mucosa (mucositis) of the middle ear. Two main forms of the chronic otitis media are distinct: the suppurative otitis media and the cholesteatoma. The suppurative otitis media is often accompanied by secretion into the external ear canal (otorrhoe), but "dry ears" are also common. Other frequent, but not obligatory symptoms are hearing impairment, tinnitus, and aural pain or pressure. Although genetically determined microbial and immunological factors, as well as Eustachian tube characteristics, are supposed to be involved in the pathogenesis of chronic suppurative otitis media, many aspects of the pathogenesis still need to be clarified. Ear microscopy will show the perforation in the drum membrane. Further diagnostic tools are audiometry, vestibular testing, radiological examination (high-resolution computed tomography) and microbiological investigation. The curative treatment for chronic suppurative otitis media is surgery (tympanoplasty, i.e. closure of the perforation in the drum membrane and also--if necessary--the reconstruction of the ossicular chain), not conservative antimicrobial therapy.

ADAMTS1 and MMP1 proteolytically engage EGF-like ligands in an osteolytic signaling cascade for bone metastasis.

Bone metastasis is mediated by complex interactions between tumor cells and resident stromal cells in the bone microenvironment. The functions of metalloproteinases in organ-specific metastasis remain poorly defined despite their well-appreciated role in matrix degradation and tumor invasion. Here, we show a mechanism whereby two distinct metalloproteinases, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS1) and matrix metalloproteinase-1 (MMP1), orchestrate a paracrine signaling cascade to modulate the bone microenvironment in favor of osteoclastogenesis and bone metastasis. Proteolytic release of membrane-bound epidermal growth factor (EGF)-like growth factors, including Amphiregulin (AREG), heparin-binding EGF (HB-EGF), and transforming growth factor alpha (TGFalpha) from tumor cells suppress the expression of osteoprotegerin (OPG) in osteoblasts and subsequently potentiate osteoclast differentiation. EGF receptor (EGFR) inhibitors block osteolytic bone metastasis by targeting EGFR signaling in bone stromal cells. Furthermore, elevated MMP1 and ADAMTS1 expression is associated with increased risk of bone metastasis in breast cancer patients. This study established MMP1 and ADAMTS1 in tumor cells, as well as EGFR signaling in osteoblasts, as promising therapeutic targets for inhibiting bone metastasis of breast cancer.