Purpose: Chondrosarcoma is the second most common malignancy in bone and results from unregulated growth of mesenchymal cells.. Chondrosarcoma does not appear to respond either to chemotherapy or radiation. Currently chondrosarcoma has no effective treatment and a new approach to adjuvant therapy for this tumor is urgently needed. We have previously reported that Matrix metalloproteinase -1 (MMP-1)gene expression is an independent predictor of survival in chondrosarcoma.(Scully, 2000). We have reported also that the expression of the large TNC splice variant may correlate with malignancy and poor clinical outcome in human chondrosarcoma and be implicated in the process of basement membrane invasion. The aim of the current study was to confirm that Tenascin-C large splice variant(TNC320) stimulates matrix metalloproteinase-1(MMP-1)expression and invasive potential and to elucidate molecular mechanisms underlying this activation.

Method: The chondrosarcoma cell line was recultured in alginate beads. (Guo et al, 1989)The beads contained exogenous proteins according to design. Alginate beads were dissociated later by chelation and the cells were pelleted by centrifugation. Gel electrophoresis and Western blotting were performed to demonstrate the expression of MMP-1 protein in the cells cultured with treatments. MMP-1 protein was detected by mouse antiMMP-1 monoclonal antibody from Chemicon. QPCR and RT-PCR were used to detect MMP-1mRNA expression with different treatments Transactivation of MMP-1 luc construct was detected in transiently transfected JJ012 human chondrosarcoma cultured cells. Reporter gene, Collagenase, Cell invasion assays and MMP-ELISA were performed for this study.

Results: The analysis of gene expression in cultured cells grown under different condition indicated significant increases of MMP-1mRNA steady-state levels in the cells with TNC 320 treatment. Gel electrophoresis demonstrated augmented MMP-1 protein in cells cultured with TNC 320. The result was confirmed by examining MMP-1 promoter transactivation of 30fold in comparison with control and other treatments. Both invasion and collagenase assays demonstrated 3 fold difference in the cells treated with TNC 320. Experiments with constitutively active expression kinases indicated that MMP-1 expression induced by TN320 was associated with MAPK cascade activation.

Conclusion: Preliminary results presented demonstrate that Tenascin-C 320kda splice variant stimulates MMP-1 expression and involves MAPK pathway. We hypothesize that Tenascin-C stimulates invasive potential of human chondrosarcoma cells via upregulation of MMP-1 expression.

Reliable soft tissue attachment to prosthetic implants remains a great clinical challenge in adult reconstruction and oncology. Past efforts using tendon alone have been universally disappointing. With the introduction of trabecular metals, new possibilities present them selves in dealing with this problem. Using an established canine supraspinatus tendon model, reliable and physiologic soft tissue attachment to a trabecular metal prosthesis was achieved, with near normal strength and function. This suggests that this new genre of material can possibly provide better options in dealing with this difficult problem.

Direct attachment of tendon to an endoprothesis has applications throughout the field of orthopaedics. The purpose of this study was to devise a soft-tissue attachment device using tantalum foam metal which would allow for early soft tissue reconstruction strength and long term biologic in-growth fixation.

A foam metal tendon attachment prosthesis was designed. Using a validated tendon attachment model, twenty-three skeletally-mature canine supraspinatus tendons were sharply detached and then reattached to the greater tuberosity. Ultimate strength, stiffness and gross morphological changes were recorded immediately after surgery and at three and six weeks.

Tendon-implant strength as percent of normal rose from thirty-nine percent at surgery, to sixty-seven percent at three weeks, and ninety-nine percent at six weeks (standard deviations thirteen, nineteen, and eighteen percent). Stiffness of construct also approached normal tendon: forty-seven percent at surgery, sixty-two percent at three weeks, and ninety-four percent at six weeks (standard deviations seventy-seven, nineteen, and eighteen percent). Supraspinatus muscle volume decreased from ninety seven (percent of normal) at surgery, to seventy-nine percent at three weeks. By six weeks, the muscle had recovered to ninety percent of normal volume. Gross and histologic analysis revealed complete tendon in-growth and attachment to the prosthesis with the formation of Sharpey’s fibers

This study suggests that tendon attachment to a metallic endoprothesis is possible. Near normal physiologic strength and stiffness was achieved six weeks post surgery. Future study should ascertain the micro-anatomy of this attachment and delineate the mechanical conditions necessary for soft tissue in-growth.

Funding: Zimmer, Inc., Warsaw, IN

Please contact author for pictures, graphs and diagrams.

Introduction and Aims: Matrix metalloproteinases can contribute to the processes of tumor invasion and metastasis. One proposed mechanism that could augment MMP-1 expression in individual patients is the existence of an Ets transcription factor-binding site in the MMP-1 promoter sequence. The aim of our study was to identify the prevalence of this single nucleotide polymorphism in chondrosarcoma patients and investigate its impact on disease outcome.

Method: Sixty-seven chondrosarcoma specimens were selected from an established tumor bank. DNA was extracted, amplified with polymerase chain reaction, and sequenced to determine the proportion of genotypes demonstrating the presence (GG) or absence (G) of the SNP at the base pair of interest. The presence of the Ets binding site was correlated with disease-free survival.

Results: Eighteen (27%) samples were G/G homozygous for absence of the Ets site, 34 (51%) were G/GG heterozygous for the SNP, and 15 (22%) were GG/GG homozygous for the SNP. The five-year overall survival rate for patients with the G/G homozygote was 78%, compared with 80% and 84% in patients with the G/GG heterozygotes and GG/GG homozygotes, respectively (p=0.5527). The disease-free survival rate of patients with the G/G genotype were 34%, compared with 74% and 100% in patients with the G/GG and GG/GG genotypes, respectively (p=0.0365).

Conclusion: The disease-free survival in patients having a GG allele was statistically better than the G allele. The observed correlation between the presence of the Ets binding site and better prognosis suggests a down-regulation of MMP-1 expression.