Jennifer L. Halpern

Osteoclast-derived matrix metalloproteinase-7, but not matrix metalloproteinase-9, contributes to tumor-induced osteolysis.

The matrix metalloproteinases MMP-2, MMP-3, MMP-7, MMP-9, and MMP-13 are highly expressed in the tumor-bone microenvironment, and, of these, MMP-7 and MMP-9 were found to be localized to bone-resorbing osteoclasts in human breast-to-bone metastases. In a bid to define the roles of host-derived MMP-7 and MMP-9 in the tumor-bone microenvironment, the tibias of MMP-7 and MMP-9 null mice were injected with osteolytic luciferase-tagged mammary tumor cell lines. Our data show that osteoclast-derived MMP-7 significantly contributes to tumor growth and tumor-induced osteolysis whereas osteoclast-derived MMP-9 had no effect on these processes. MMP-7 is capable of processing a number of nonmatrix molecules to soluble active forms that have profound effects on cell-cell communication, such as RANKL, a crucial mediator of osteoclast precursor recruitment and maturation. Therefore, the ability of osteoclast-derived MMP-7 to promote RANKL solubilization in the tumor-bone microenvironment was explored. Results revealed that levels of soluble RANKL were significantly lower in the MMP-7 null mice compared with wild-type (WT) controls. In keeping with this observation, MMP-7 null mice had significantly fewer osteoclast numbers at the tumor-bone interface compared with the WT controls. In summary, we propose that the solubilization of RANKL by MMP-7 is a potential mechanism through which MMP-7 mediates mammary tumor-induced osteolysis. Our studies indicate that the selective inhibition of MMP-7 in the tumor-bone microenvironment may be of benefit for the treatment of lytic breast-to-bone metastases.

Mesenchymal stem cells promote mammary cancer cell migration in vitro via the CXCR2 receptor.

Bone metastasis is a common event during breast cancer progression. Recently, mesenchymal stem cells (MSCs) have been implicated in the metastasis of primary mammary cancer. Given that bone is the native environment for MSCs, we hypothesized MSCs facilitate the homing of circulating mammary cancer cells to the bone. To test this hypothesis, we examined in vitro whether bone derived MSCs from FVB mice could influence the migration of syngeneic murine mammary cancer cell lines derived from the polyoma virus middle-T (PyMT) model of mammary gland tumorigenesis. Our data show that conditioned media derived from MSCs significantly enhanced the migration of PyMT mammary cancer cell lines. Analysis of conditioned media using a cytokine array revealed the presence of numerous cytokines in the MSC conditioned media, most notably, the murine orthologs of CXCL1 and CXCL5 that are cognate ligands of the CXCR2 receptor. Further investigation identified that: (1) CXCL1, CXCL5 and CXCR2 mRNA and protein were expressed by the MSCs and PyMT cell lines and; (2) neutralizing antibodies to CXCL1, CXCL5 and CXCR2 or a CXCR2 small molecule inhibitor (SB265610) significantly abrogated the migratory effect of the MSC conditioned media on the PyMT cells. Therefore, in vitro evidence demonstrates that bone derived MSCs play a role in the migration of mammary cancer cells, a conclusion that has potential implications for breast to bone metastasis in vivo.

Methylthioadenosine phosphorylase and activated insulin-like growth factor-1 receptor/insulin receptor: potential therapeutic targets in chordoma.

Currently there is no effective chemotherapy for chordoma. Recent studies report co‐expression of insulin‐like growth factor‐1 receptor (IGF1R) and its cognate ligand in chordoma, but it is unknown whether this receptor tyrosine kinase is activated in these tumours. Additionally, genetic studies have confirmed frequent deletions of chromosome 9p in chordomas, which encompasses the cyclin‐dependent kinase inhibitor 2A (CDKN2A) locus. Another gene in this region, methylthioadenosine phosphorylase (MTAP), is an essential enzyme of the purine salvage pathway and has therapeutic relevance because MTAP‐deficient cells are particularly sensitive to inhibitors of de novo purine synthesis. We investigated whether these pathways might be potential therapeutic targets for chordoma. Paraffin‐embedded tissue samples from 30 chordomas were analysed by immunohistochemistry for expression of the phosphorylated isoforms of IGF1R or the insulin receptor (pIGF1R/pIR) and selected downstream signalling molecules, including BCL2‐associated agonist of cell death protein (BAD). Expression of CDKN2A and MTAP proteins was also assessed. Skeletal chondrosarcomas, benign notochordal cell tumours, and fetal notochord were studied for comparison. Phosphorylated IGF1R/IR was detected in 41% of chordomas, together with activated downstream signalling molecules, and pIGF1R/pIR was absent in benign notochordal cell tumours and fetal notochord. Thirty‐nine per cent of chordomas were negative for MTAP immunoreactivity. Patients with pIGF1R/pIR‐positive tumours showed significantly decreased median disease‐free survival in multivariate survival analysis (p = 0.036), whereas phosphorylation of BAD at serine‐99 was found to be associated with a favourable prognosis (p = 0.002). Approximately 40% of chordomas demonstrate evidence of activation of the IGF1R/IR signalling pathway or loss of a key enzyme in the purine salvage pathway. Aberrant signalling cascades and disrupted metabolic pathways such as these may represent opportunities for novel targeted therapeutic approaches for the treatment of chordoma. Copyright

Allograft ankle arthrodesis: a limb salvage technique for distal tibial tumors.

Allograft ankle arthrodesis using a retrograde intramedullary tibial nail is a new strategy in limb salvage for treatment of distal intraarticular tibial tumors. After tumor resection, the ankle is reconstructed using an intercalary allograft and retrograde intramedullary fixation. We retrospectively reviewed nine consecutive patients with intraarticular resection of distal tibial tumors who had allograft ankle arthrodesis reconstruction between April 1994 and August 2000. Patient charts were reviewed for: (1) local recurrence, new metastases, and survival; (2) Musculoskeletal Tumor Society score7; and (3) complications or reoperations or both. Only one of nine patients had a local recurrence. Eight of nine patients achieved independent ambulation. Eight of nine patients had a Musculoskeletal Tumor Society score greater than 73%. Six of nine patients required nine additional operations. No patients required flap coverage. There were no superficial or deep infections. Allograft ankle arthrodesis is a new alternative in limb salvage for distal tibial tumors. It has oncologic outcomes (rate of local recurrence, new metastases, and survival from time of diagnosis) and functional outcomes (Musculoskeletal Tumor Society score and rates of reoperation) comparable to previously reported and accepted methods of limb salvage. Level of Evidence: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Prognostic significance of c-Myc expression in soft tissue leiomyosarcoma.

The biological potential of soft tissue leiomyosarcoma is difficult to predict using current standard prognostic parameters, and control of systemic disease is challenging with current chemotherapeutic protocols. Additional prognostic markers and alternative treatment options are very much required. Previous studies implicate upregulation of the oncogenic nuclear transcription factor c-Myc with aggressive behavior of many solid tumors. Therefore, this oncoprotein was evaluated as a prognostic marker for overall and metastasis-free survival in leiomyosarcoma. Immunohistochemical stains for c-Myc were performed on 28 cases of leiomyosarcoma occurring in the deep somatic soft tissues. Comparisons of Kaplan–Meier survival curves stratified by c-Myc status and conventional prognostic factors (histological grade, tumor size, and tumor stage) were evaluated using standard univariate statistical methods. A subsequent multivariate survival analysis was carried out according to the Cox proportional hazards regression model adjusting for potential confounding prognostic factors. A total of 15 cases (54%) were positive for nuclear c-Myc expression. Patients with c-Myc-positive tumors had significantly shorter metastasis-free survival intervals compared with those with c-Myc-negative tumors (median, 9 months vs. >94 months; P=0.014). c-Myc positivity also correlated with decreased overall survival (median, 23 months vs. >94 months; P=0.017). Histological grade was the only other prognostic marker predictive of poor outcome in the univariate analyses. In the multivariate survival analysis, only c-Myc status reached statistical significance, suggesting that it is an important and independent predictor of prognosis in leiomyosarcoma. Detection of nuclear c-Myc in leiomyosarcoma predicts decreased overall and metastasis-free survival, independent of standard prognostic variables, tumor size, histological grade, and TNM stage. The expression of this oncoprotein may represent a useful prognostic marker and potential therapeutic target in leiomyosarcoma.

Signal transduction pathway analysis in desmoid-type fibromatosis: transforming growth factor-β, COX2 and sex steroid receptors.

Despite reports of sex steroid receptor and COX2 expression in desmoid‐type fibromatosis, responses to single agent therapy with anti‐estrogens and non‐steroidal anti‐inflammatory drugs are unpredictable. Perhaps combination pharmacotherapy might be more effective in desmoid tumors that co‐express these targets. Clearly, further understanding of the signaling pathways deregulated in desmoid tumors is essential for the development of targeted molecular therapy. Transforming growth factor–β (TGFβ) and bone morphogenetic proteins (BMP) are important regulators of fibroblast proliferation and matrix deposition, but little is known about the TGFβ superfamily in fibromatosis. A tissue microarray representing 27 desmoid tumors was constructed; 14 samples of healing scar and six samples of normal fibrous tissue were included for comparison. Expression of selected receptors and activated downstream transcription factors of TGFβ family signaling pathways, β–catenin, sex steroid hormone receptors and COX2 were assessed using immunohistochemistry; patterns of co–expression were explored via correlational statistical analyses. In addition to β–catenin, immunoreactivity for phosphorylated SMAD2/3 (indicative of active TGFβ signaling) and COX2 was significantly increased in desmoid tumors compared with healing scar and quiescent fibrous tissue. Low levels of phosphorylated SMAD1/5/8 were detected in only a minority of cases. Transforming growth factor–β receptor type 1 and androgen receptor were expressed in both desmoid tumors and scar, but not in fibrous tissue. Estrogen receptor–β was present in all cases studied. Transforming growth factor–β signaling appears to be activated in desmoid‐type fibromatosis and phosphorylated SMAD2/3 and COX2 immunoreactivity might be of diagnostic utility in these tumors. Given the frequency of androgen receptor, estrogen receptor–β and COX2 co‐expression in desmoid tumors, further assessment of the efficacy of combination pharmacotherapy using hormonal agonists/antagonists together with COX2 inhibitors should be considered.

Eye Protection in Orthopaedic Surgery: An in Vitro Study of Various Forms of Eye Protection and Their Effectiveness

BACKGROUND Conjunctival contamination from splashed debris during orthopaedic surgical procedures places surgeons at risk for communicable diseases such as human immunodeficiency virus (HIV) and hepatitis B and C. The purpose of this study was to compare the effectiveness of various types of protective eyewear in preventing conjunctival contamination. METHODS A simulation model was constructed with use of a mannequin head in a typical position of a surgeons head during an operation. The head was placed at an appropriate distance from the surgical field, and a femoral osteotomy was performed on a cadaver thigh. Six experimental groups were tested to determine the ability of various types of eye protection to prevent contamination of the conjunctiva: (1) modern prescription glasses, (2) standard surgical telescopic loupes, (3) hard plastic contoured glasses, (4) disposable plastic glasses, (5) a combination facemask and eye shield, and (6) no protection (control). Thirty femoral osteotomies were performed, and contamination of both the protective devices and the simulated conjunctival surfaces were recorded. RESULTS None of the tested devices were completely effective. The modern prescription glasses and the controls both were associated with conjunctival contamination rates of 83%. The other eye protective devices were associated with significantly lower rates of overall contamination, with a rate of 50% for the loupes, 30% for the facemask and eye shield, 17% for the hard plastic glasses, and 3% for the disposable plastic glasses. CONCLUSIONS Modern prescription glasses provided no benefit over the control in our experimental model; therefore, we do not recommend that they be used as the sole eye protection, especially during surgical procedures in which there is a high rate of debris expulsion from the wound. Readily available and disposable plastic glasses were associated with the lowest rate of conjunctival contamination (3%) and are an effective means with which to protect the orthopaedic surgeon from communicable diseases by conjunctival contamination.

Morphologic and immunophenotypic analysis of desmoid-type fibromatosis after radiation therapy ☆

The morphologic changes seen in desmoid-type fibromatosis after radiotherapy have not been well studied, and the degree of cytologic atypia, cellularity, mitotic activity, and lesional necrosis found in desmoid-type fibromatosis treated with ionizing radiation has not been thoroughly assessed. Therefore, we evaluated a series of primary and locally recurrent desmoid-type fibromatoses resected at variable intervals after radiation therapy (XRT) and compared their histopathologic and immunophenotypic features with paired pathologic specimens that were obtained before radiotherapy. The morphologic characteristics of desmoid-type fibromatoses resected before and after radiotherapy were not significantly different in 7 of the 8 cases studied. One case resected 191 months after XRT showed morphologic evidence of fibrosarcomatous transformation, with zonal necrosis, hypercellularity, severe nuclear atypia, and increased mitotic activity. No significant differences in the immunophenotype of desmoid-type fibromatosis were observed after XRT. In rare cases of recurrent desmoid-type fibromatosis, the differential diagnosis may include radiation-induced fibrosarcoma. Our data suggest that histomorphologic alterations attributable to the effects of ionizing radiation in desmoid-type fibromatosis are minimal. Therefore, the presence of cytologic features of malignancy in this setting warrants careful examination and consideration of the rare occurrence of postradiation sarcoma. Lesser degrees of nuclear atypia seen in isolation do not necessarily indicate a poor prognosis in irradiated desmoid-type fibromatosis.

Serum Levels of Methyl Methacrylate Following Inhalational Exposure to Polymethylmethacrylate Bone Cement

UNLABELLED Teratogenic effects of polymethylmethacrylate cement at levels used during routine orthopaedic procedures have never been reported, however the hypothetical risk remains a major concern among female surgeons. Our aim was to determine if methyl methacrylate is detectible in the serum during routine cement exposure. METHODS Twenty healthy volunteers were exposed during the mixing of polymethylmethacrylate cement in a simulated operating room environment. Forty serum samples were obtained during the expected peak inhalational exposure and levels of methyl methacrylate were assessed utilizing headspace gas chromatography mass spectrometry. RESULTS Methyl methacrylate was not detected in any of the forty experimental specimens. CONCLUSIONS With a detection level of 0.5 ppm, methyl methacrylate is undetectable in the serum during routine mixing of polymethylmethacrylate cement.

Sarcopenia Does Not Affect Survival or Outcomes in Soft-Tissue Sarcoma

Background and Objective. Sarcopenia is associated with decreased survival and increased complications in carcinoma patients. We hypothesized that sarcopenic soft-tissue sarcoma (STS) patients would have decreased survival, increased incidence of wound complications, and increased length of postresection hospital stay (LOS). Methods. A retrospective, single-center review of 137 patients treated surgically for STS was conducted. Sarcopenia was assessed by measuring the cross-sectional area of bilateral psoas muscles (total psoas muscle area, TPA) at the level of the third lumbar vertebrae on a pretreatment axial computed tomography scan. TPA was then adjusted for height (cm2/m2). The association between height-adjusted TPA and survival was assessed using Cox proportional hazard model. A logistical model was used to assess the association between height-adjusted TPA and wound complications. A linear model was used to assess the association between height-adjusted TPA and LOS. Results. Height-adjusted TPA was not an independent predictor of overall survival (p = 0.746). Patient age (p = 0.02) and tumor size (p = 0.009) and grade (p = 0.001) were independent predictors of overall survival. Height-adjusted TPA was not a predictor of increased hospital LOS (p = 0.66), greater incidence of postoperative infection (p = 0.56), or other wound complications (p = 0.14). Conclusions. Sarcopenia does not appear to impact overall survival, LOS, or wound complications in patients with STS.