Osteoblastic Lesions Research Articles

CT Guided Bone Biopsy Using a Battery Powered Intraosseous Device

To evaluate the feasibility of a battery powered intraosseous device to perform CT-fluoroscopy guided bone biopsy. Retrospective analysis of 12 patients in whom bone specimen were acquired from different locations under CT-fluoroscopy guidance using the OnControl bone marrow biopsy system (OBM, Vidacare, Shavano Park, TX, USA). Data of the 12 were compared to a historic cohort in whom the specimen were acquired using the classic Jamshidi Needle, as reference needle using manual force for biopsy. Technical success was reached in 11 of 12 cases, indicated by central localisation of the needle within the target lesion. All specimen sampled were sufficient for histopathological workup. Compared to the historical cohort the time needed for biopsy decreased significantly from 13 ± 6 to 6 ± 4 min (P = 0.0001). Due to the shortened intervention time the radiation dose (CTDI) during CT-fluoroscopy was lowered significantly from 169 ± 87 to 111 ± 54 mGy × cm (P = 0.0001). Interventional radiologists were confident with the performance of the needle especially when using in sclerotic or osteoblastic lesions. The OBM is an attractive support for CT-fluoroscopy guided bone biopsy which is safe tool and compared to the classical approach using the Jamshidi needle leading to significantly reduced intervention time and radiation exposure.

Evidence of Stress Fracture in a Homo antecessor Metatarsal from Gran Dolina Site (Atapuerca, Spain)

AbstractWe present the palaeopathological analysis of a right fourth metatarsal (ATD6‐124) recovered from the Atapuerca–Gran Dolina site (Spain). This fossil, ca. 1 Ma, belongs to Homo antecessor, the earliest known European hominin species. The metatarsal exhibits a proliferative lesion on its medial periosteal surface. Periosteal reaction can be the bone response to a wide number of injurious processes. We describe a lesion on the basis of macroscopic and microscopic analyses, including microtomography and scanning electron microscopy. Externally, the osteoblastic lesion presents a highly porotic and disorganised morphology. Internally, we observe a series of micro‐fractures on the compact bone that do not affect the medullary canal. We provide a differential diagnosis and suggest that the ATD6‐124 lesion could correspond to a pedal stress fracture, also known as fatigue or march fracture. Stress fractures have been related to a load increase and muscular fatigue. This type of fracture has been widely reported in the foot of soldiers and athletes, which are usually engaged in strenuous, excessive or prolonged locomotive activities. Despite its high frequency in these groups, stress fractures have not been reported as such in fossil collections, with the exception of a metatarsal belonging to the Sima de los Huesos site (Atapuerca). Copyright © 2013 John Wiley & Sons, Ltd.

A phase II randomized clinical trial of samarium-153 EDTMP (Sm-153) with or without PSA-TRICOM vaccine in metastatic castration-resistant prostate cancer (mCRPC) after docetaxel.

102 Background: A prior randomized, placebo-controlled, multi-center phase 2 trial of PSA-TRICOM demonstrated survival benefit. Sm-153 is a radiopharmaceutical that targets osteoblastic lesions. Preclinical data indicated that Sm-153 could alter tumor phenotype, causing upregulation of Fas, MHC Class I, and tumor-associated antigens, making tumor cells more amenable to immune-mediated killing. This trial was intended to examine the safety and efficacy of the Sm-153 with PSA-TRICOM vs. Sm-153 alone. Methods: This phase 2 multi-center trial was designed to randomize 68 pts to Sm-153 with or without PSA-TRICOM. Eligibility included mCRPC, bone metastases, no visceral disease, prior docetaxel, ECOG ≤2, and normal organ function. Sm-153 was given at 1mCi/kg IV on day 8 and then every 12 weeks. PSA-TRICOM was given on days 1, 15, 29, then every 4 weeks. The 1° endpoint was comparison of progression-free survival at 4 months (mo) utilizing PCCWG, but not PSA criteria. A Fisher’s exact test, assuming a one-tailed alpha = 0.10, was used to compare these fractions. 2° endpoints were OS, ORR, PSA changes, immunologic, and toxicity. Results: 44 pts were enrolled, 5 were not evaluable for the 1° endpoint due to withdrawal prior to 4 mos (4 on Arm A, 1 on Arm B). PFS and PSA findings are provided below. Hematologic toxicities were most common, and were well matched. Conclusions: This final analysis suggests the combination of PSA-TRICOM and Sm-153 has a similar toxicity profile to Sm-153 alone. Despite early closure of this trial due to poor accrual, which may be related to recent approval of multiple agents for mCRPC, this analysis appears to demonstrate improvement in PFS with the combination. This may indicate synergy between PSA-TRICOM and bone-seeking radiopharmaceuticals. Based on the data presented here, we are exploring the potential to combine PSA-TRICOM with alpharadin (radium-223), a next generation bone-seeking radiopharmaceutical. Clinical trial information: NCT00450619. [Table: see text]

Abstract C47: Assessing the role of Wnt secretion in prostate cancer skeletal metastasis

Abstract Aberrant Wnt signaling is associated with prostate cancer tumorigenesis, progression, and bone metastasis. Bone metastasis is responsible for substantial morbidity and mortality in patients with advanced prostate cancer. No curative treatment currently exists for patients with bone metastasis. Wnt signaling plays an integral role in the bone-tumor environment during prostate cancer bone metastasis, particularly osteoblastic lesion formation, but the cell type that secretes Wnt ligands in this process is unknown. This knowledge would result in improved targeting strategies for chemotherapeutics. We hypothesize that Wnt ligand secretion by prostate tumor cells is necessary to establish and/or mediate progression of prostate tumor growth and associated bone formation within the skeleton. We targeted two proteins that are essential for Wnt secretion. Porcupine (Porcn) is an acyltransferase responsible for adding fatty acids to Wnt ligands, which precedes their interaction with the chaperone protein Wntless (Wls). Both Porcn and Wls are essential for Wnt ligand secretion. Without secretion, Wnt ligands are retained inside Wnt-producing cells, and therefore cannot activate Wnt receptors in an autocrine or paracrine manner. Using shRNA, we created stable Wls knockdown C42B4 prostate cancer cell lines and confirmed knockdown via quantitative PCR. We saw that when Wls is knocked down by approximately 95%, the Wnt target gene Axin2 decreased in expression by approximately 50%. This indicates that autocrine signaling is occurring in these cells, supporting our hypothesis. We have also generated three xenograft models in immune-deficient Nod-Scid-ILR2gamma-deficient (NSG) mice and are currently assessing the ability of Wls-deficient cells to metastasize and establish tumors in bone. In addition, we will treat mice injected with prostate cancer cells with a chemical Porcn inhibitor to determine the therapeutic value of such inhibitors in treating advanced prostate cancer. Given that Porcn inhibitors are in early stage human clinical trials for other cancers, our work could provide support for using said inhibitors for treatment of patients with advanced prostate cancer. Citation Format: Kenneth C. Valkenburg, Bart O. Williams. Assessing the role of Wnt secretion in prostate cancer skeletal metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C47.

Animal model for mammary tumor growth in the bone microenvironment

Advanced breast cancer commonly spreads to the bones, lungs, liver or brain, and bone is the most common site of breast cancer metastasis. Nearly all patients with advanced breast cancer develop bone metastasis and suffer from serious bone metastasis-associated complications, including chronic pain, fracture, spinal cord compression and hypercalcemia. Metastasis formation in the bone is a complex process that requires cooperative reciprocal interactions between tumor cells and the cellular environment of the bone, which includes osteoclasts and osteoblasts. We have developed a murine bone invasion model of breast cancer, which required a simple surgical technique and mimics the biology of the disease. Osteolytic and/or osteoblastic lesions induced in the tumor-bone interface allowed us to explore cellular and molecular interactions between malignant cells and skeletal tissue in a syngeneic setting. In this review, we will discuss a different animal model that provides a consistent and reproducible platform for investigating the molecular mechanisms underlying tumor-bone interaction and breast cancer-induced osteolytic changes.

Effectiveness of Bone Metastases Treatment by Sm-153 Oxabifore in Combination with Monoclonal Antibody Denosumab (Xgeva): First Experience

Breast and prostate cancer have a propensity to metastasize to bones and cause osteolysis and abnormal new bone formation. Metastases locally disrupt normal bone remodeling. Although metastases from prostate cancer have been classified as osteoblastic based on the radiographic appearance of the lesion, data gleaned from a rapid autopsy program indicate that the same prostate cancer patient may have evidence of both osteolytic and osteoblastic disease as shown by histologic examinations. Thus, bone metastases are heterogeneous, requiring combined treatment targeting on both osteolytic and osteoblastic lesions. While Samarium-153 (Sm-153) oxabifore treatment is widely used for the relief of pain in patients with osteoblastic metastatic bone lesions, Xgeva (Denosumab) is indicated for the prevention of skeletal-related events in patients with bone metastases from solid tumors. It is a fully human monoclonal antibody that has been designed to target receptor activator of nuclear factor-kB ligand (RANKL), a protein that acts as the primary signal to promote bone removal. In many bone loss conditions, RANKL overwhelms the body's natural defense against bone destruction. The main objectives of the current pilot study were to estimate the effectiveness of bone metastases treatment by a combination of Sm-153 oxabifore and Xgeva (Denosumab). Five patients (four female and one male, aged 35-64, mean age 50.8) with multiple skeletal metastases from prostatic carcinoma (1) and breast carcinoma (4) were studied. Their mean objective pain score according to visual analog scoring system on a 1-10 scoring system was 7.8 ± 0.5 (range 6-9). Sm-153 oxabifore was administered at the standard bone palliation dose of 37 MBq/kg body weight. Xgeva (Denosumab) was administered at a dosage of 120 mg every 4 weeks, with the monitoring of calcium level and administration of calcium, magnesium, and vitamin D. Whole body (WB) bone scan was performed before and 3 months after treatment in all patients. After Sm-153 oxabifore administration, pain relief occurred within 4.4 ± 1.25 days (range 2-9 days) and the objective pain score decreased to 0.2 ± 0.2 (range 0-1). There was statistically significant difference found, according to the pain score system, before and after treatment (P < 0.0001). WB bone scan showed that in one patient, there was significant reduction in the number and intensity of bone metastases, and in four patients, there was no evidence of bone metastases found. Based on our first experience, combined treatment of bone metastases with Sm-153 oxabifore and Denosumab is effective and safe.

High prevalence of osteoblastic bone reaction in computed tomography scans of an European Organisation for Research and Treatment of Cancer prospective randomised phase II trial in extensive stage small cell lung cancer

BackgroundOsteoblastic bone reaction is an important phenomenon defined by an increase in apparent bone density of previously known bone metastasis or development of new osteoblastic lesions in the presence of response in other tumour sites. Osteoblastic bone reaction in lung cancer has only been described in a few reports and mostly in patients with pre-existing bone metastasis. MethodsIn this report we present the data of an independent, blinded and preplanned radiological review of the occurrence of osteoblastic lesions in patients with extensive stage small cell lung cancer (SCLC). The computed tomography (CT) scans of the chest and upper abdomen of 71/88 patients who had an investigator reported complete response (CR), partial response (PR) or stable disease (SD) were retrospectively analysed for the development of osteoblastic lesions. Furthermore, baseline exams were reviewed for the presence and location of bone metastasis and local radiological reports were reviewed for any knowledge of bone metastasis. ResultsThere were 14 patients with osteoblastic bone lesions in the reviewed follow-up CT scans. Three patients had known bone metastases at baseline, and 11 patients had no history or findings of bone metastases on the baseline scan. During the course of the disease, 13 out of 14 patients developed new osteoblastic lesions, while all responded in other sites. The prevalence of osteoblastic bone reaction in our study was 19.7%. ConclusionIn this study osteoblastic bone reaction was observed in a larger number of patients without previously documented bone metastases, indicating a high prevalence of occult bone metastases in SCLC. If bone metastases are not documented at diagnosis, then osteoblastic bone reaction may cause confusion in a responding patient.

Interim analysis of a phase II randomized clinical trial of samrium-153 (Sm-153) with or without PSA-TRICOM vaccine in metastatic castration-resistant prostate cancer after docetaxel.

2526 Background: A prior randomized, placebo-controlled, multi-center phase 2 trial of PSA-TRICOM (PROSTVAC) demonstrated an overall survival benefit. Sm-153 is a radiopharmaceutical that targets osteoblastic bone lesions. Preclinical data indicated that Sm-153 could alter tumor phenotype, causing upregulation of Fas, MHC Class I, and tumor-associated antigens, making tumor cells more amenable to immune-mediated killing. Methods: This is a phase 2 multi-center trial design intended to randomize 68 patients (pts) to Sm-153 with or without PROSTVAC. Eligibility included castrate resistant prostate cancer bone metastases, no visceral disease, prior docetaxel, ECOG ≤2, and normal organ function. Sm-153 was given at 1mCi/kg IV on day 8 and then every 12 weeks. PROSTVAC was given on days 1, 15, 29, then every 4 weeks. The 1° endpoint is a comparison of progression-free survival at 4 months (mo) utilizing PCCWG, but not PSA criteria. 68 patients will provide 80% power to detect a difference of 15% vs. 40% without progression at 4 mo with a one-tailed alpha = 0.10 assuming Fisher’s exact test comparing these fractions as the primary method of analysis. 2° endpoints are OS, ORR, PSA changes, immunologic, toxicity, and palliation. Reported here is the result of a pre-specified interim analysis, which required ≥20% conditional power to detect 15% vs. 40% without progression at 4 months for the trial to continue. Results: Of 37 enrolled pts, 3 were not evaluable for PFS. PFS and PSA findings are found below. Hematologic toxicities (anemia, thrombocytopenia, neutropenia, or lymphocytopenia) are most common, with grade 3 or 4 thrombocytopenia occurring in 22% and 26% of treatment cycles on Arms A and B, respectively. The conditional power for the comparison of fractions without progression at 4 mo is 77%. Conclusions: This interim analysis suggests the combination of PROSTVAC and Sm-153 is well tolerated with similar toxicity profile to Sm-153 alone. The early indication of improved TTP warrants continued study accrual. [Table: see text]

The IGR-CaP1 Xenograft Model Recapitulates Mixed Osteolytic/Blastic Bone Lesions Observed in Metastatic Prostate Cancer

Bone metastases have a devastating impact on quality of life and bone pain in patients with prostate cancer and decrease survival. Animal models are important tools in investigating the pathogenesis of the disease and in developing treatment strategies for bone metastases, but few animal models recapitulate spontaneous clinical bone metastatic spread. In the present study, IGR-CaP1, a new cell line derived from primary prostate cancer, was stably transduced with a luciferase-expressing viral vector to monitor tumor growth in mice using bioluminescence imaging. The IGR-CaP1 tumors grew when subcutaneously injected or when orthotopically implanted, reconstituted the prostate adenocarcinoma with glandular acini-like structures, and could disseminate to the liver and lung. Bone lesions were detected using bioluminescence imaging after direct intratibial or intracardiac injections. Anatomic bone structure assessed using high-resolution computed tomographic scans showed both lytic and osteoblastic lesions. Technetium Tc 99m methylene diphosphonate micro single-photon emission computed tomography confirmed the mixed nature of the lesions and the intensive bone remodeling. We also identified an expression signature for responsiveness of IGR-CaP1 cells to the bone microenvironment, namely expression of CXCR4, MMP-9, Runx2, osteopontin, osteoprotegerin, ADAMTS14, FGFBP2, and HBB. The IGR-CaP1 cell line is a unique model derived from a primary tumor, which can reconstitute human prostate adenocarcinoma in animals and generate experimental bone metastases, providing a novel means for understanding the mechanisms of bone metastasis progression and allowing preclinical testing of new therapies.

Abstract 1479: Targeting breast cancer bone metastases looking at the cross-talk between tumor cells and bone environment

Abstract Metastatic dissemination is a major cause of cancer associated death; in breast cancer, bone, lung and brain are the major sites of tumor relapse. Bone marrow (BM) is a reservoir for metastatic breast cancer cells that can enter into a quiescent state and remain latent even for decades after dissemination. By still unknown mechanisms, dormant tumor cells can reacquire proliferative ability, thereby causing osteolytic or osteoblastic lesions. During these processes BM environment and tumor cells strongly influence each other. We aimed to analyze molecular mechanisms involved in the liaison between tumor cells and BM microenvironment. More specifically, we investigated how breast cancer cells can affect BM stoma when they home to the endosteal niche and how bone microenvironment can influence the behavior of tumor cells. We took advantage of the MDA-MB231 SCP1833 subclone, which after intracardiac injection has a high propensity for bone metastases. Tumor cell dissemination was followed by bioluminescence imaging and when BM metastases were detected different cell populations from the bone environment were isolated by cell sorting. We excluded cells of the hematopoietic compartment from the analysis, concentrating on the CD45- population. We used the best available antibodies that define osteoblast (CD45-, TR119-, Sca1-, CD51+), endothelial cells (CD45-, TR119-, Sca1+, CD31+) and mesenchymal progenitors (CD45-, TR119-, CD31-, Sca1+) for sorting in order to compare BM populations from tumor-bearing mice with un-injected control mice by a genome wide-transcriptome study. Microarray analysis revealed that BM is strongly affected by breast cancer cell dissemination. Indeed, several components of key molecular pathways involved in tumor development (including TGFBR, PDGFRB, EGFR, HGFR and IGFR signaling pathways) are modulated in the BM of mice with tumor cells. We are following up this analysis by testing the effects of the PI3K-mTOR inhibitor BEZ-235 in breast cancer bone metastases. PIK3CA, that is a downstream effector of several of the above-mentioned pathways, is up-regulated in the bone stroma of tumor-bearing mice. Besides the effect of BEZ-235 on tumor cells, we want to elucidate how the BM responds to PI3K pathway inhibition, and how this influences survival and proliferation of tumor cells. To investigate the effect of BM environment on disseminated tumor cells, we compared the expression profile of MDA-MB231 SCP1833 from the mammary fad pad, i.e, the primary tumor, with tumor cells isolated from BM. We have uncovered some transcripts for surface proteins whose expression is down-regulated in cancer cells that have homed to the BM, compared to tumor cells growing in the mammary fad pad. These and other results that will be presented show the important role that the environment plays on the tumor cell transcriptome and ultimately on the response to therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1479. doi:1538-7445.AM2012-1479

Abstract 5317: Role of TGF-beta superfamily ligand and mechanism of osteoblastic tumorigenesis of prostate cancer cells

Abstract Prostate cancer is the second leading cause of cancer related death in men in the US. The skeleton is the most common site for prostate cancer metastasis, which often results in osteoblastic lesions. Transforming growth factor-beta (TGFβ), which is a multifunctional cytokine, is important for the regulation of bone mass and matrix properties. Our group has recently shown that TGFβ signaling helps in promoting osteoblastic tumor growth by a novel human prostate cancer cell line, PacMetUT1. However, the mechanism by which prostate cancer cells metastasize to bone and how they induce formation of osteoblastic lesions remains to be intensively investigated. Bone cells such as osteoblasts express aromatase, which is the enzyme required for estrogen biosynthesis in humans. Recent data further implicates an aberrant aromatase expression and estrogen signaling in the development of prostate malignancy. Hence we hypothesize that TGFβ and other growth factors released from tumor cells can induce aromatase gene expression and activity in bone cells leading to an enhanced estradiol synthesis which would in turn lead to an increase in bone formation as estrogen is a known osteogenic factor. We examined the effect of TGFβ superfamily ligands on aromatase expression in pre-osteoblastic cells. Treatment with TGFβ1 and BMP-4/7 resulted in an increase in aromatase expression in both mouse pre-osteoblasts and human bone marrow-derived mesenchymal stem cells (MSC's). This increase in aromatase expression was abrogated after transient knockdown of Smad's in MSC's. Treatment with letrozole (aromatase inhibitor) as well as an anti-estrogen (ICI 182, 780) resulted in a decrease in osteoblastic differentiation of mesenchymal stem cells as measured by alkaline phosphatase activity assay and expression of osteogenic markers by quantitative real-time PCR analysis. Furthermore, PacMetUT1 cells were found to be responsive to 17-β estradiol treatment. 17-β estradiol treatment of PacMetUT1 cells resulted in an enhanced anchorage- dependent and independent cell growth in vitro. 17-β estradiol also induced a change in cell morphology of PacMetUT1 cells with a reduction in E-cadherin expression and an increase in Vimentin expression at both protein and mRNA level. This affect was abrogated after stable estrogen receptor alpha (ERα) knockdown in PacMetUT1 cells. Our results demonstrate an aromatase-mediated induction of osteogenesis by TGFβ superfamily ligands in the pre-osteoblastic cells and a stimulatory effect of estrogen signaling on PacMetUT1 cell tumorigencity in vitro. Future studies will delineate whether the induction of aromatase mediates osteoblastic bone metastasis of prostate cancer cells in vivo and if combination treatment of TGFβ and aromatase inhibitors can be used as a novel therapeutic strategy to alleviate bone metastasis in prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5317. doi:1538-7445.AM2012-5317

Abstract LB-300: The role of WNT7B in prostate cancer bone metastasis

Abstract Prostate cancer is the most common cancer for men in the US. It is well known that the androgen receptor (AR), a master transcription factor in prostate, plays a critical role in all stages of prostate cancer. There has been a dedicated interest in identification of downstream AR target genes responsible for prostate cancer growth and progression. Using chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq), we identified WNT7B as a direct AR target gene in both androgen-dependent LNCaP and androgen-independent C4-2B cells. Knockdown of WNT7B by RNA interference inhibits the growth of LNCaP and C42B cells, accompanied by a corresponding increase in apoptosis as determined by Caspase-3 and -7 activities. Overexpression of WNT7B promotes the growth of C4-2B cells in the absence of androgen. One of the major challenges in prostate cancer research is the propensity for bone metastasis, which displays characteristic osteoblastic lesions. Since WNT7B plays an important role in bone formation, we asked whether prostate cancer-produced WNT7B induces osteoblast differentiation using an in vitro model of the murine osteoblast precursor ST2 cell line. We found that in a co-culture system, overexpression of WNT7B in LNCaP and C42B cells induces osteoblastic differentiation of ST2 cells, as indicated by increased alkaline phosphatase production, bone sialoprotein (an early marker for osteoblast differentiation) expression, and mineralization. On the other hand, knockdown of WNT7B in prostate cancer cells inhibits the differentiation of ST2 cells. These results indicate that WNT7B can stimulate the growth of prostate cancer cells as an autocrine agent and induce osteoblastic differentiation in bone metastases as a paracrine agent. WNT7B may be a potential therapeutic target for prostate cancer bone metastasis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-300. doi:1538-7445.AM2012-LB-300

Abstract 2464: Novel MMP-3 generated PTHrP peptides promote osteoblast proliferation: Implications for prostate to bone metastases

Abstract Up to 90% of patients that succumb to prostate cancer will have evidence of bone metastasis. Prostate to bone metastases generate mixed lesions hallmarked by areas of extensive bone resorption and formation mediated by osteoclasts and osteoblasts respectively. Tumor derived PTHrP has been defined as a major molecule facilitating tumor-osteoblast interaction. Mature PTHrP is comprised of 36 amino-acids and new data from our lab has identified that MMP-3, one of several MMPs we have found highly expressed in the prostate cancer-bone microenvironment, can process PTHrP to yield novel distinct peptides. We posit that MMP-3 generated PTHrP peptides can have distinct biological effects on osteoblasts. Our results to date demonstrate that MMP-3 processes mature PTHrP to yield PTHrP1-16, PTHrP17-26, and PTHrP27-36 amino acid peptides in vitro as determined by N-terminal amino acid sequencing and MALDI-TOF analysis. Next, we determined the biological activity of the MMP-3 generated PTHrP peptides by treating osteoblast cell lines and examining differentiation and proliferation. We found using alizarin red staining that the MMP-3 generated PTHrP peptides did not impact osteoblast differentiation. However, analysis of cell proliferation, using an MTT assay, identified that the PTHrP1-16 peptide stimulated osteoblast proliferation over a 24-hour period. Follow-up studies revealed that the MMP-3 generated PTHrP1-16 fragment significantly enhanced phosphorylation of MAPK 42/44 and CREB, presumably via the PTHrP receptor, PTH1R. In conclusion, our data identify for the first time that PTHrP is an MMP substrate and that MMP-3 generated PTHrP peptide PTHrP1-16, can promote osteoblast proliferation. These findings suggest that MMP-3 expression in the prostate tumor microenvironment can potentially impact osteoblast expansion and may play a role in the generation of osteoblastic lesions that are commonly associated with prostate to bone metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2464. doi:1538-7445.AM2012-2464

Follow-up CT and MR findings of osteoblastic spinal metastatic lesions after stereotactic radiotherapy

We retrospectively analyzed pre and post-stereotactic radiotherapy CT and MRI findings and volume changes for osteoblastic spinal metastatic lesions. Of 114 lesions in 72 patients, 11 were osteoblastic. CT and MR images were reviewed to determine tumor volume, CT attenuation, T2 signal intensities, and contrast enhancement. Tumor volume did not change for 10 lesions and increased for 1 lesion. CT attenuation increased for 8 lesions with heterogeneous T2 signal intensities. Of these 8 lesions, 4 had patterns of dark signal foci and the other 4 had patterns of both dark and bright signal foci. T2 signal intensity became heterogenous, with dark and bright foci, for 2 of 3 lesions for which CT attenuation decreased, and normalized for the third lesion. The degree of contrast enhancement decreased for 6 lesions and did not change for 5 lesions. There were no changes in volume except for one case. On CT images, sclerotic changes were more common than loss of sclerotic foci. On T2-weighted images, dark signal intensities with or without bright signal foci developed and the degree of enhancement decreased for more than half of the cases.

The Role of Bone-Seeking Radionuclides in the Palliative Treatment of Patients with Painful Osteoblastic Skeletal Metastases

Pain from skeletal metastases represents a major burden of advanced disease from solid tumors. Analgesic medications, bisphosphonates, hormonal agents, cytotoxic chemotherapy, and external beam radiotherapy are all effective treatments. However, patients often suffer from diffuse painful metastases and respond poorly to these standard therapies. Bone-seeking radionuclides can specifically target osteoblastic lesions to offer palliation of pain. This article offers a narrative review of bone-seeking radionuclides, examines the evidence of safety and efficacy for the treatment of painful skeletal metastases, and presents guidelines for their appropriate use in this patient population. Seven bone-seeking radionuclides have shown evidence of both safety and efficacy in reducing pain from diffuse skeletal metastases. 153Sm-EDTMP and 89Sr are most commonly used in the United States and have been safely utilized for both repeat dosing as well as concurrent dosing with cytotoxic chemotherapy. Targeted bone-seeking radionuclides are underutilized in the treatment of painful diffuse osteoblastic metastases. Several new agents are in active clinical investigation, and the pending approval of the first alpha-emitting radionuclide (223Ra) may offer a new class of agents that provide greater efficacy and less toxicity than those currently available for routine clinical use.

Disseminated Prostate Cancer Cells Can Instruct Hematopoietic Stem and Progenitor Cells to Regulate Bone Phenotype

Prostate cancer metastases and hematopoietic stem cells (HSC) frequently home to the bone marrow, where they compete to occupy the same HSC niche. We have also shown that under conditions of hematopoietic stress, HSCs secrete the bone morphogenetic proteins (BMP)-2 and BMP-6 that drives osteoblastic differentiation from mesenchymal precursors. As it is not known, we examined whether metastatic prostate cancer cells can alter regulation of normal bone formation by HSCs and hematopoietic progenitor cells (HPC). HSC/HPCs isolated from mice bearing nonmetastatic and metastatic tumor cells were isolated and their ability to influence osteoblastic and osteoclastic differentiation was evaluated. When the animals were inoculated with the LNCaP C4-2B cell line, which produces mixed osteoblastic and osteolytic lesions in bone, HPCs, but not HSCs, were able to induced stromal cells to differentiate down an osteoblastic phenotype. Part of the mechanism responsible for this activity was the production of BMP-2. On the other hand, when the animals were implanted with PC3 cells that exhibits predominantly osteolytic lesions in bone, HSCs derived from these animals were capable of directly differentiating into tartrate-resistant acid phosphatase-positive osteoclasts through an interleukin-6-mediated pathway. These studies for the first time identify HSC/HPCs as novel targets for future therapy involved in the bone abnormalities of prostate cancer.

P2X7 Receptor Function in Bone-Related Cancer

Modulation of tumor microenvironment by different mediators is central in determining neoplastic formation and progression. Among these molecules extracellular ATP is emerging as a good candidate in promoting cell growth, neovascularization, tumor-host interactions, and metastatization. This paper summarizes recent findings on expression and function of P2X7 receptor for extracellular ATP in primary and metastatic bone cancers. Search of mRNA expression microchip databases and literature analysis demonstrate a high expression of P2X7 in primary bone tumors as well as in other malignancies such as multiple myeloma, neuroblastoma, breast, and prostate cancer. Evidence that P2X7 triggers NFATc1, PI3K/Akt, ROCK, and VEGF pathways in osteoblasts promoting either primary tumor development or osteoblastic lesions is also reported. Moreover, P2X7 receptor is involved in osteoclast differentiation, RANKL expression, matrix metalloproteases and cathepsin secretion thus promoting bone resorption and osteolytic lesions. Taken together these data point to a pivotal role for the P2X7 receptor in bone cancer biology.

Osteosarcoma Diagnostic Delay Associated With Alendronate-Induced Pain Relief

A 32-year-old man with a painful osteoblastic osteosarcoma of the right hip was initially diagnosed as having Paget's disease of bone. He was treated with alendronate for presumptive Paget's disease. The patient's bone pain was dramatically reduced by the administration of alendronate for 7 months. Following discontinuation of alendronate, his pain promptly recurred, culminating in a more thorough evaluation that led to the correct diagnosis. Despite chemotherapy, the patient succumbed to metastatic osteosarcoma. The main purpose of this publication is to report the potential for pain relief when an osteosarcoma is treated with bisphosphonate medication. Clinicians are advised not to consider an alendronate-associated pain reduction in an osteoblastic lesion as an indicator of an underlying benign process of bone. The evaluation of painful sclerotic bone lesions is briefly reviewed.

Small (&lt;4 cm), Unclassified Renal Cell Carcinoma Presenting with Initial Bone Metastasis: A Case of a Metastatic Lesion Missed at the Initial Diagnosis

A 49-year-old man presented with an incidentally detected right renal mass on a health examination. The abdominal computed tomography and magnetic resonance imaging showed a 3-cm right renal mass suspected of being a hypovascular tumor, such as papillary renal cell carcinoma, and an osteoblastic metastatic lesion on the right iliac bone. However, we missed a bone lesion at the time of diagnosis. A laparoscopic radical nephrectomy was performed and the final pathology confirmed unclassified renal cell carcinoma. The follow-up imaging studies showed several neck lymph nodes and multiple bone metastases at the lumbar spine, right iliac bone, and left femur. Thirteen cycles of temsirolimus were administered to the patient, but follow-up positron emission tomography showed newly developed liver and left adrenal metastasis and increased bone metastasis. It is important to note that T1a renal cell carcinoma can present with distant metastasis and thus demands scrupulous examination even though the tumor size may be small.

Registered and potential indications of FDG PET/CT in breast carcinoma

The indication of 18F-fluorodeoxyglucose (FDG) imaging has been more disputed in breast carcinoma than in many other primary cancers (e.g. lung, head and neck, colorectal, lymphoma...) due to a limited sensitivity to detect the primary tumours in case of lobular or in situ forms or small sized tumours detected on systematic mammography, and to identify minimal node invasion in the axilla. Nevertheless dedicated PET machines are now proposed to characterise breast lesions. For staging locally advanced or restaging recurrent or metastatic breast cancer, FDG PET/CT has a good diagnostic performance. As a functional whole-body imaging modality, it is able to detect extra-axilar metastatic lymph nodes, distant metastases including in the skeleton, where it outperforms bone scintigraphy or SPECT except in case of osteoblastic lesions, or to discover second primary cancers (around 2% of cases). A potential indication is monitoring response to chemotherapy, to early detect disease resistance or progression. To summarise published results and our own experience, the breast tumour SUVmax decreases with the number of cycles in most patients, including those who will show residual disease on pathology. It is therefore best to perform FDG PET/CT at baseline and after 1 cycle of chemotherapy; the criterion for prediction of an incomplete pathologic response would be a SUVmax reduction <50%. In case of adjuvant chemotherapy, the visual interpretation of FDG PET/CT performed after 5 months may be sufficient to predict disease-free survival; the response to chemotherapy evaluated by FDG PET is a better predictor of recurrence-free survival than pathologic response.