Anthony G. Montag

Characterization of the distinct orthotopic bone-forming activity of 14 BMPs using recombinant adenovirus-mediated gene delivery.

Efficacious bone regeneration could revolutionize the clinical management of bone and musculoskeletal disorders. Although several bone morphogenetic proteins (BMPs) (mostly BMP-2 and BMP-7) have been shown to induce bone formation, it is unclear whether the currently used BMPs represent the most osteogenic ones. Until recently, comprehensive analysis of osteogenic activity of all BMPs has been hampered by the fact that recombinant proteins are either not biologically active or not available for all BMPs. In this study, we used recombinant adenoviruses expressing the 14 types of BMPs (AdBMPs), and demonstrated that, in addition to currently used BMP-2 and BMP-7, BMP-6 and BMP-9 effectively induced orthotopic ossification when either AdBMP-transduced osteoblast progenitors or the viral vectors were injected into the quadriceps of athymic mice. Radiographic and histological evaluation demonstrated that BMP-6 and BMP-9 induced the most robust and mature ossification at multiple time points. BMP-3, a negative regulator of bone formation, was shown to effectively inhibit orthotopic ossification induced by BMP-2, BMP-6, and BMP-7. However, BMP-3 exerted no inhibitory effect on BMP-9-induced bone formation, suggesting that BMP-9 may transduce osteogenic signaling differently. Our findings suggest that BMP-6 and BMP-9 may represent more effective osteogenic factors for bone regeneration.

Connective tissue growth factor (CTGF) is regulated by Wnt and bone morphogenetic proteins signaling in osteoblast differentiation of mesenchymal stem cells

Osteoblast lineage-specific differentiation of mesenchymal stem cells is a well regulated but poorly understood process. Both bone morphogenetic proteins (BMPs) and Wnt signaling are implicated in regulating osteoblast differentiation and bone formation. Here we analyzed the expression profiles of mesenchymal stem cells stimulated with Wnt3A and osteogenic BMPs, and we identified connective tissue growth factor (CTGF) as a potential target of Wnt and BMP signaling. We confirmed the microarray results, and we demonstrated that CTGF was up-regulated at the early stage of BMP-9 and Wnt3A stimulations and that Wnt3A-regulated CTGF expression was β-catenin-dependent. RNA interference-mediated knockdown of CTGF expression significantly diminished BMP-9-induced, but not Wnt3A-induced, osteogenic differentiation, suggesting that Wnt3A may also regulate osteoblast differentiation in a CTGF-independent fashion. However, constitutive expression of CTGF was shown to inhibit both BMP-9- and Wnt3A-induced osteogenic differentiation. Exogenous expression of CTGF was shown to promote cell migration and recruitment of mesenchymal stem cells. Our findings demonstrate that CTGF is up-regulated by Wnt3A and BMP-9 at the early stage of osteogenic differentiation, which may regulate the proliferation and recruitment of osteoprogenitor cells; however, CTGF is down-regulated as the differentiation potential of committed pre-osteoblasts increases, strongly suggesting that tight regulation of CTGF expression may be essential for normal osteoblast differentiation of mesenchymal stem cells.

Regulation of osteogenic differentiation during skeletal development.

Bone formation during skeletal development involves a complex coordination among multiple cell types and tissues. Bone is of crucial importance for the human body, providing skeletal support, and serving as a home for the formation of hematopoietic cells and as a reservoir for calcium and phosphate. Bone is also continuously remodeled in vertebrates throughout life. Osteoblasts and osteoclasts are specialized cells responsible for bone formation and resorption, respectively. Early development of the vertebrate skeleton depends on genes that control the distribution and proliferation of cells from cranial neural crest, sclerotomes, and lateral plate mesoderm into mesenchymal condensations, where cells differentiate to osteoblasts. Significant progress has been made over the past decade in our understanding of the molecular framework that controls osteogenic differentiation. A large number of morphogens, signaling molecules, and transcriptional regulators have been implicated in regulating bone development. A partial list of these factors includes the Wnt/beta-catenin, TGF-beta/BMP, FGF, Notch and Hedgehog signaling pathways, and Runx2, Osterix, ATF4, TAZ, and NFATc1 transcriptional factors. A better understanding of molecular mechanisms behind osteogenic differentiation would not only help us to identify pathogenic causes of bone and skeletal diseases but also lead to the development of targeted therapies for these diseases.

CCN1/Cyr61 Is Regulated by the Canonical Wnt Signal and Plays an Important Role in Wnt3A-Induced Osteoblast Differentiation of Mesenchymal Stem Cells

ABSTRACT Marrow mesenchymal stem cells are pluripotent progenitors that can differentiate into bone, cartilage, muscle, and fat cells. Wnt signaling has been implicated in regulating osteogenic differentiation of mesenchymal stem cells. Here, we analyzed the gene expression profile of mesenchymal stem cells that were stimulated with Wnt3A. Among the 220 genes whose expression was significantly changed by 2.5-fold, we found that three members of the CCN family, CCN1/Cyr61, CCN2/connective tissue growth factor (CTGF), and CCN5/WISP2, were among the most significantly up-regulated genes. We further investigated the role of CCN1/Cyr61 in Wnt3A-regulated osteogenic differentiation. We confirmed that CCN1/Cyr61 was up-regulated at the early stage of Wnt3A stimulation. Chromatin immunoprecipitation analysis indicates that CCN1/Cyr61 is a direct target of canonical Wnt/β-catenin signaling. RNA interference-mediated knockdown of CCN1/Cyr61 expression diminished Wnt3A-induced osteogenic differentiation. Furthermore, exogenously expressed CCN1/Cyr61 was shown to effectively promote mesenchymal stem cell migration. These findings suggest that tightly regulated CCN1/Cyr61 expression may play an important role in Wnt3A-induced osteoblast differentiation of mesenchymal stem cells.

Loss of E-Cadherin Promotes Ovarian Cancer Metastasis via α5-Integrin, which Is a Therapeutic Target

E-cadherin loss is frequently associated with ovarian cancer metastasis. Given that adhesion to the abdominal peritoneum is the first step in ovarian cancer dissemination, we reasoned that down-regulation of E-cadherin would affect expression of cell matrix adhesion receptors. We show here that inhibition of E-cadherin in ovarian cancer cells causes up-regulation of alpha(5)-integrin protein expression and transcription. When E-cadherin was blocked, RMUG-S ovarian cancer cells were able to attach and invade more efficiently. This greater efficiency could, in turn, be inhibited both in vitro and in vivo with an alpha(5)beta(1)-integrin-blocking antibody. When E-cadherin is silenced, alpha(5)-integrin is up-regulated through activation of an epidermal growth factor receptor/FAK/Erk1-mitogen-activated protein kinase-dependent signaling pathway and not through the canonical E-cadherin/beta-catenin signaling pathway. In SKOV-3ip1 ovarian cancer xenografts, which express high levels of alpha(5)-integrin, i.p. treatment with an alpha(5)beta(1)-integrin antibody significantly reduced tumor burden, ascites, and number of metastasis and increased survival by an average of 12 days when compared with IgG treatment (P < 0.0005). alpha(5)-Integrin expression was detected by immunohistochemistry in 107 advanced stage ovarian cancers using a tissue microarray annotated with disease-specific patient follow-up. Ten of 107 tissues (9%) had alpha(5)-integrin overexpression, and 39% had some level of alpha(5)-integrin expression. The median survival for patients with high alpha(5)-integrin levels was 26 months versus 35 months for those with low integrin expression (P < 0.05). Taken together, we have identified alpha(5)-integrin up-regulation as a molecular mechanism by which E-cadherin loss promotes tumor progression, providing an explanation for how E-cadherin loss increases metastasis. Targeting this integrin could be a promising therapy for a subset of ovarian cancer patients.

Diagnostic Accuracy and Charge-Savings of Outpatient Core Needle Biopsy Compared with Open Biopsy of Musculoskeletal Tumors*

We performed a prospective study of sixty-two patients who were managed with a closed core needle biopsy in an outpatient clinic for a soft-tissue mass or a bone tumor with soft-tissue extension between August 1, 1992, and June 1, 1994. Eight (13 per cent) of the closed core needle biopsies yielded no neoplastic tissue. Two needle biopsies (3 per cent), which were of myxomatous masses, did not allow distinction between a benign and a malignant neoplasm; both masses were extraskeletal myxoid chondrosarcomas. Additionally, the histological grade of four resected specimens (6 per cent) differed from that determined with the closed needle biopsy. The diagnostic accuracy of the closed needle biopsies was 84 per cent (fifty-two of sixty-two). All ten diagnostic errors involved soft-tissue tumors. A retrospective study of a similar cohort of patients, who had open biopsy in an outpatient operating room by the same surgeon in a contemporary period in the same institution and with analysis by the same pathologist, revealed a diagnostic accuracy of 96 per cent (forty-eight of fifty). The hospital charges for the closed core needle biopsy were

Osteogenic BMPs promote tumor growth of human osteosarcomas that harbor differentiation defects

1106, compared with

A randomized phase III trial in advanced endometrial carcinoma of surgery and volume directed radiation followed by cisplatin and doxorubicin with or without paclitaxel: A Gynecologic Oncology Group study☆ , ☆☆

7234 for the open biopsy. We concluded that core needle biopsy can be performed in an outpatient clinic with use of local anesthesia and that it is substantially less expensive and more convenient than open biopsy. This technique has an acceptable but definitely lower rate of accuracy compared with open biopsy, especially for soft-tissue tumors, and it should be used only in a small subset of patients (those who have a large soft-tissue mass or a bone tumor with palpable soft-tissue extension). However, given the small size of the tissue sample, the clinician must recognize possible disadvantages, including a non-diagnostic biopsy, an indeterminate biopsy, or a potential error in the histological grade. These problems are much more likely to occur after core needle biopsy of soft-tissue masses. Because of the potential for errors in diagnosis when core needle biopsy is used, the musculoskeletal oncologist must rely on his or her clinical acumen. When a diagnostic is in reasonable doubt, there is no radiographic confirmation, the biopsy shows no tumor cells, or there is a combination of these findings, operative decisions should be made as if no biopsy had been performed. The management of patients who, after core needle biopsy, have a diagnosis of a bone or soft-tissue tumor, is best carried out by an experienced musculoskeletal oncologist working in close collaboration with an experienced musculoskeletal pathologist.

Cytoplasmic and/or nuclear accumulation of the β‐catenin protein is a frequent event in human osteosarcoma

Osteosarcoma (OS) is the most common primary malignancy of bone. Here, we investigated a possible role of defective osteoblast differentiation in OS tumorigenesis. We found that basal levels of the early osteogenic marker alkaline phosphatase (ALP) activity were low in OS lines. Osteogenic regulators Runx2 and OSX, and the late marker osteopontin (OPN) expressed at low levels in most OS lines, indicating that most OS cells fail to undergo terminal differentiation. Furthermore, OS cells were refractory to osteogenic BMP-induced increases in ALP activity. Osteogenic BMPs were shown to upregulate early target genes, but not late osteogenic markers OPN and osteocalcin (OC). Furthermore, osteogenic BMPs failed to induce bone formation from human OS cells, rather effectively promoted OS tumor growth in an orthotopic OS model. Exogenous expression of early target genes enhanced BMP-stimulated OS tumor growth, whereas osteogenic BMP-promoted OS tumor growth was inhibited by exogenous Runx2 expression. These results suggest that alterations in osteoprogenitors may disrupt osteogenic differentiation pathway. Thus, identifying potential differentiation defects in OS tumors would allow us to reconstruct the tumorigenic events in osteoprogenitors and to develop rational differentiation therapies for clinical OS management.

BMP-14 Gene Therapy Increases Tendon Tensile Strength in a Rat Model of Achilles Tendon Injury

OBJECTIVES After surgical debulking and volume-directed irradiation of the pelvis/para-aortic lymph nodes, treatment was randomized to compare recurrence-free survival (RFS) and toxicity between two chemotherapy regimens for the treatment of women with advanced stage endometrial carcinoma. METHODS Treatment was randomized between 6 cycles of cisplatin [C] (50 mg/m(2)) and doxorubicin [D] (45 mg/m(2)) with or without paclitaxel [P] (160 mg/m(2)). Initially in paclitaxel treated patients and, after May 2002, all patients received granulocyte growth factor with each cycle. RESULTS Of 659 patients enrolled following surgery, 552 eligible patients were randomized to chemotherapy after irradiation. Accrual closed to Stage IV patients in June, 2003. Approximately 80% completed six cycles of chemotherapy. Three deaths resulted from bowel complications and one death was due to renal failure. Hematologic adverse events, sensory neuropathy and myalgia, were more frequent and severe in the paclitaxel arm (p<0.01) which was confirmed by Quality of Life assessments. Percentage of patients alive and recurrence-free at 36 months was 62% for CD vs. 64% for CDP. The hazard of recurrence or death relative to the CD arm stratified by stage is 0.90 (95% CI is 0.69 to 1.17, p=0.21, one-tail). However, in subgroup analysis, CDP was associated with a 50% reduction in the risk of recurrence or death among patients with gross residual disease (95% CI: 0.26 to 0.92). Stage, residual disease, histology/grade, positive para-aortic node and cytology, pelvic metastases and age were significantly associated with RFS. CONCLUSION The addition of paclitaxel to cisplatin and doxorubicin following surgery and radiation was not associated with a significant improvement in RFS but was associated with increased toxicity.