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The ultrastructure of small-cell osteosarcoma, with a review of the light microscopy and differential diagnosis.

Small-cell osteosarcoma is a rare form of osteosarcoma and often poses difficulty in differential diagnosis when tissue samples do not include any diagnostic osteoid. By light microscopy, it may be difficult to distinguish small-cell osteosarcoma from other small-cell neoplasms, especially Ewing's sarcoma and mesenchymal chondrosarcoma. Relatively little has been reported about the ultrastructural characteristics of small-cell osteosarcoma, whereas electron microscopic examination has proven very useful in the diagnosis of most other small-cell neoplasms. We have studied four proven small-cell osteosarcomas in detail at the electron microscopic level and found their common features to be a high nucleocytoplasmic ratio, poorly differentiated cytoplasm, numerous free ribosomes and mitochondria as the next most prevalent organelle, small junctions, and envelopment of individual and groups of cells by matrix. Beyond these characteristics, cytoplasmic organelles and nuclear features varied, and no single pathognomonic ultrastructural picture was observed. However, within the range of possible ultrastructure of small-cell osteosarcoma, most small-cell neoplasms can be ruled out. Only certain examples of Ewing's sarcoma and mesenchymal chondrosarcoma may be indistinguishable from it when osteoid is not present in the sample.

Adolescent↗

Characterization of PMP22 expression in osteosarcoma.

The peripheral myelin protein (PMP22) gene is highly expressed in peripheral Schwann cells and encodes an important constituent of the myelin sheath. It is also expressed at lower levels in other normal tissues in which the protein is supposed to be involved in cell growth regulation. We recently reported frequent amplification and overexpression of PMP22 in high-grade osteosarcoma. Here, we analyzed PMP22 expression in five osteosarcoma tumors and three osteosarcoma cell lines. In normal Schwann cells, transcription of PMP22 starts at three promoters, P1A, P1B, and P2, which results in the synthesis of three alternatively spliced transcripts that all code for the same protein. We found a comparable expression pattern in normal osteoblasts. However, promoter P1A-driven transcripts were absent in all investigated tumors and cell lines and, compared to normal osteoblasts, the P1B/P2 transcript ratio was found to be increased in two of three cases with PMP22 overexpression and decreased in all five cases without overexpression. In normal Schwann cells and in NIH3T3 cells, PMP22 expression increases upon serum starvation-induced growth arrest. In contrast to this, serum withdrawal caused a considerable decrease of PMP22 expression in the osteosarcoma cell lines. We conclude that the different PMP22 expression in osteosarcoma may result in alternative availability of the PMP22 protein during the cell cycle and aberrant regulation of cell growth control in osteosarcoma tumorigenesis.

Alternative Splicing↗

CD9 expression is not a prognostic factor in human osteosarcoma.

CD 9, also known as Motility-Related Protein-1 (MRP-1), is a member of the transmembrane four superfamily and plays a crucial role in cell adhesion, motility and signalling events. Downregulation of CD 9 has been reported to be associated with tumour progression, metastasis and clinical outcome in various kinds of solid tumours. Although prognosis of osteosarcoma has been improved by chemotherapy during the last decades, the problem of non-responders remains. At the present time prognostic factors at diagnosis have not been clearly identified. Furthermore, there is a need for markers that predict the response to chemotherapy at the time of biopsy, allowing stratification of osteosarcoma patients. In this study we investigated the effect of CD9 expression on the response to chemotherapy and survival in osteosarcoma. The expression of CD9 was examined immunohistochemically in 52 patients with high grade osteosarcoma and the results were correlated with histologic response to chemotherapy, 5 year disease free and 5 year overall survival. In patients with osteosarcoma 22 of 52 cases (42%) were positive for CD 9 expression, the rest were negative. CD 9 expression status showed no statistically significant correlation with response to chemotherapy; 41% had a poor response and 59% a good response in the CD9 positive group. In the CD9 negative group 57% had a good and 47% had a bad response. No significant difference was found when comparing disease free survival (58.9% in CD9 positive- versus 69.3% in CD9 negative tumours; P = 0.99) and overall survival of patients (54.0% in CD9 positive- versus 58.1% in CD9 negative tumours; P = 0.90) with CD9 expressing tumours to those with reduced CD9 expression. In conclusion our findings suggest that in contrast to solid tumours, CD9 is unlikely to provide any additional prognostic information for clinical purposes in osteosarcoma patients.

Adult↗

Commonly used mouse models of osteosarcoma.

Osteosarcoma is the commonest primary tumour of bone and the second highest cause of cancer-related death in the paediatric age group. Little is known of the aetiology of human osteosarcoma and lesser still of the various interactions that occur between host and tumour cells that govern growth and progression of osteosarcoma in vivo. Although numerous osteosarcoma cell lines have been established and characterized in vitro, some as far back as in the 1960s, there is a scarcity of reliable and reproducible in vivo animal models that mimics all aspects of the human condition at the temporal, physiological and histopathological level, hence, making the accurate testing of therapeutic strategies difficult. Given that osteosarcoma is a disease that affects young people and better disease management strategies are essential, development of a robust human osteosarcoma model is long overdue.

Animals↗

Clinico-histologic parameters of osteosarcoma patients with late relapse.

Primary high-grade intramedullary osteosarcoma of the extremities is a clinically aggressive bone tumour. There is an ongoing effort to further improve efficacy of neo-adjuvant chemotherapy and reduce chemotoxicity by trying to identify osteosarcoma patients who are at risk of treatment failure as well as to identify those who can do with less chemotherapy. In only 5% of patients, first distant metastasis or local relapse occurs 5 years or more after initial treatment for osteosarcoma. Patients and physicians can therefore easily erroneously consider a patient with osteosarcoma cured if he or she is disease-free for more than 5 years following diagnosis and treatment. To investigate if these rare late relapsing patients are characterised by specific clinico-pathological features, we examined clinical and histological variables of late relapse (first local recurrence or metastasis 5 years or more after initial diagnosis) out of a total of 2,243 patients, with a special interest in the histological osteosarcoma subtype. In total, 33 patients had a documented relapse 5 years or more after diagnosis. Half of the patients had good response (>or=90% necrosis) to pre-operative chemotherapy and the other half a poor response (<90% necrosis) and late relapses seemed to be more frequently proportionately in those who had a good initial response to chemotherapy. The occurrence of late relapse did not appear to be associated with age or gender. Although not statistically significant, there was a trend for patients with a chondroblastic subtype of osteosarcoma, or a location in the tibia or fibula, to have a higher risk for late relapse.

Adolescent↗

Anomalous cadherin expression in osteosarcoma. Possible relationships to metastasis and morphogenesis.

Two isoforms of the human cadherin-11/OB-cadherin gene, the intact and the variant forms, had been isolated from an osteosarcoma cDNA library. The intact form has a typical cadherin structure, whereas the variant form, generated by alternative splicing, encodes a cytoplasmic domain that is completely different from that of the intact form and lacks a homophilic cell-cell adhesion ability. At the protein level, the secreted form generated from the intact cadherin-11 is present. We examined the expression of the intact and the variant forms of cadherin-11 in 23 primary and metastatic osteosarcomas from 22 patients by reverse transcriptase-polymerase chain reaction (RT-PCR) analyses, revealing that all 23 tumors in the patients expressed the variant form and three of them expressed it prominently. On the other hand, Western blot analyses of six tumors showed that the secreted form was strongly expressed, and furthermore, expression of N-cadherin was extremely low. Overexpression of the intact cadherin-11 cDNA in osteosarcoma cell lines demonstrated that the secreted form is derived from the intact form of cadherin-11 in osteosarcoma. Immunohistochemically, cadherin-11, N-cadherin, and beta-catenin were expressed at the cell surface of fetal osteoblasts, whereas in osteosarcoma cells, they were expressed only focally or weakly in the cytoplasm. Considering the function of cadherin in carcinomas, it is suggested that the anomalous expression of human cadherin-11 in osteosarcoma and the reduced expression of N-cadherin play a role in metastasis and the irregular morphology in the highly malignant mesenchymal tumor.

Bone Development↗

Novel findings in gene expression detected in human osteosarcoma by cDNA microarray.

cDNA microarray analysis was used to screen for gene expression alterations in human osteosarcoma cell lines. The analysis using three cell lines revealed changes in the expression of several genes in comparison with normal human osteoblasts. Among the 5,184 sequences that were analyzed, 35 showed aberrant expression in all the cell lines. Eight of these showed overexpression and 27 underexpression compared to their expression levels in osteoblasts. The most highly up-regulated genes included heat shock protein 90beta and polyadenylate-binding protein-like 1. Commonly down-regulated genes included fibronectin 1 and thrombospondin 1. RT-PCR was used to verify these changes in the cell lines and in three primary osteosarcoma samples. This study shows that (1) gene expression pattern in osteosarcoma cell lines differs considerably from normal osteoblasts, (2) osteosarcoma cell lines can be used as a model system to detect novel gene expression alterations present in primary tumors, (3) the overexpression of heat shock protein 90beta and polyadenylate-binding protein-like 1, and (4) the down-regulation of fibronectin 1 and thrombospondin 1 may play a role in the development and/or progression of osteosarcoma. This study indicates that microarray-based expression surveys may be used to establish the molecular fingerprint of osteosarcoma, however, larger cDNA chips and more tumor specimens are required to define the clinically relevant gene expression patterns.

DNA, Complementary↗

Cytogenetic findings in 73 osteosarcoma specimens and a review of the literature.

Tumor-specific chromosomal abnormalities have been identified in several histologic subtypes of sarcomas. Characterization of recurrent chromosomal abnormalities has provided direction for molecular investigations of pathogenetically important genes. Cytogenetic reports of osteosarcoma, the most common primary malignant bone tumor, are relatively rare. In this study, 73 osteosarcoma specimens from 51 patients were cytogenetically analyzed following short-term culture. Clonal chromosomal abnormalities were detected in 47 and included one haploid specimen, 18 near-diploid specimens, 17 near-triploid, 8 near-tetraploid, 1 near-hexaploid, and 2 specimens with multiple clones of different ploidy levels. Examination of the present data and previously published data (111 clonally abnormal osteosarcoma specimens) reveals that chromosomal bands or regions 1p11-13, 1q10-12, 1q21-22, 11p15, 12p13, 17p12-13, 19q13, and 22q11-13 are most frequently rearranged and the most common numerical abnormalities are +1, -9, -10, -13, and -17. Partial or complete loss of the long arm of chromosome 6 also was seen in all cases of the present study and all previously published cases describing structural abnormalities of 6q. Parosteal osteosarcoma, a prognostically favorable osteosarcoma subtype, was characterized by the presence of a ring chromosome accompanied by no or few other abnormalities. Complex karyotypes were seen nearly exclusively in the high-grade lesions. These findings indicate that specific chromosomal bands and/or regions are nonrandomly involved in osteosarcoma and may provide useful clinical information.

Adolescent↗

Analysis of the p16INK4, p14ARF, p15, TP53, and MDM2 genes and their prognostic implications in osteosarcoma and Ewing sarcoma.

We examined alterations of the p16INK4, p14ARF, p15, TP53, and MDM2 genes in 30 osteosarcomas and 24 Ewing sarcomas. Among 21 osteosarcomas and 24 Ewing sarcomas, p16INK4, p14ARF, and p15 abnormalities were found in 4 (19%), 2 (9%), and 3 (14%) osteosarcomas, respectively, and in 4 (17%), 3 (13%), and 4 (17%) Ewing sarcomas, respectively. The alterations of p16INK4, p14ARF, and p15 included homozygous deletions spanning all 3 genes, methylation of p16INK4 or p15, and a nonsense mutation of p16INK4, which simultaneously caused a missense mutation of p14ARF. Alterations of TP53 were found in 15 (50%) of 30 osteosarcomas and 1 (3%) of 24 Ewing sarcomas. None of the sarcomas showed MDM2 amplification. While TP53 abnormalities were far more frequent in osteosarcoma than in Ewing sarcoma, alterations of p16INK4, p14ARF, and p15 were present at similar frequencies in the two types of sarcoma. The event-free survival (EFS) was worse in Ewing sarcoma patients with p16INK4 and p14ARF mutation/deletion than in those without the mutation/deletion (P = 0.019), and EFS was worse in osteosarcoma patients with TP53 alterations than in those without TP53 alterations (P = 0.048). The different incidence of TP53 abnormalities in the 2 types of sarcoma may reflect differences of the molecular processes through which the 2 types of tumor develop.

Adolescent↗

Relationship between P-glycoprotein positivity, doxorubicin binding ability and histologic response to chemotherapy in osteosarcomas.

We previously reported that the doxorubicin binding ability detected by the doxorubicin (adriamycin) binding assay was closely correlated with the chemosensitivity of human osteosarcomas. In this study, we undertook to clarify the relationship between P-glycoprotein positivity (%PPG) and doxorubicin binding ability (%DB) in human osteosarcomas in order to determine which is a more sensitive index of histologic response to chemotherapy. Ten primary osteosarcomas were analyzed by the doxorubicin binding assay and by immunofluorescence to detect cellular P-glycoprotein positivity. Three good responders to chemotherapy containing doxorubicin showed a %DB greater than 90% (average: 96.43%), whereas the seven poor responders had values less than 80% (average: 35.31%). The difference between the two groups was statistically significant (P = 0.0167). However, the average %PPG of the three good responders was 6.73%, whereas the %PPG of the seven poor responders was 14.27%. There was no significant difference in %PPG between the two groups (P = 0.3051). No negative correlation between the %DB and the %PPG of all osteosarcomas (r = 0.536, P = 0.1104) was found, although there was a trend that those tumors with a high %PPG showed a low %DB. These results suggest that osteosarcomas showing a low %DB and %PPG with poor response to chemotherapy, may have multidrug resistance mechanisms other than P-glycoprotein. Therefore, we conclude that doxorubicin binding ability, which reflects all of the doxorubicin-resistant mechanisms, was more sensitive than P-glycoprotein positivity in predicting the chemosensitivity of human osteosarcoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Prognostic factor studies in oncology: osteosarcoma as a clinical example.

OBJECTIVE: Prognostic factor studies are abundant in oncology. Nevertheless, most of them have very limited impact on clinical practice, in part because many of them have a low statistical power. The importance of statistical power is illustrated using bootstrap resampling of data from a series of osteosarcoma patients. METHODS AND MATERIALS: Osteosarcoma is a rare disease, the incidence being just a few cases per million person-years in the Western World. Very few Phase III studies have been conducted in the disease, and much knowledge on therapeutic progress has come from Phase II studies. This has caused controversy concerning the validity of historical controls, which again has stimulated interest in the identification of prognostic factors in this disease. A literature search in the National Library of Medicine MEDLINE database was performed to identify prognostic factor studies in osteosarcoma published between 1975 and 1998. Monte Carlo methods, so-called bootstrap resampling, are used to investigate the importance of sample size based on survival data for a previously published series of 158 osteosarcomas treated with surgery alone. RESULTS: Most published studies are too small to provide useful information on prognostic factors in osteosarcoma. Three-quarters of the papers reviewed included less than 100 patients with osteosarcoma. More than 20 different potential prognostic factors were included in these papers. Inherent differences between studies and poor reporting hamper a synthesis of information from various studies. The results from the bootstrap resampling illustrate how the majority of published studies would miss even quite significant prognostic factors. CONCLUSIONS: An effort is needed to improve the design, conduct, and reporting of prognostic studies in oncology.

Bone Neoplasms↗

Osteosarcoma over the age of forty.

The European Musculo Skeletal Oncology Society (EMSOS) has carried out a retrospective review of patients over the age of 40 years with osteosarcoma. 481 patients from 12 centres or multicentric groups were included. 42 patients had osteosarcoma arising in Paget's disease, median survival was 9 months. Patients with axial or metastatic tumours also did badly whilst 41 patients with radiation-induced osteosarcoma had a prognosis paralleling conventional osteosarcoma matched for patient age and site of the tumour. 238 patients had high grade non-metastatic osteosarcoma and had a survival of 46% at 5 years. Older patients had less chemotherapy and fared worse. Osteosarcoma in the elderly is a curable condition and warrants intensive treatment with chemotherapy and surgical resection.

Adult↗

Suramin suppresses growth, alkaline-phosphatase and telomerase activity of human osteosarcoma cells in vitro.

Neoadjuvant chemotherapy in osteosarcoma improves the survival dramatically, but there is currents drug resistance in about 25% of patients, leading researchers to investigate alternative therapy forms. Suramin has in the last two decades been used as salvage therapy in some cancers. This study was undertaken to investigate suramin as a possible salvage therapy in osteosarcoma. The effect of suramin on three human osteosarcoma cell lines (MG-63, HOS and SaOS-2) and three primary osteosarcoma cell lines isolated from biopsies was investigated. Suramin significantly inhibited cell proliferation, determined by 3H-thymidine incorporation, of osteosarcoma cells at a dose ranging from 250 to 500 microg/ml. Suramin decreased the secretion of alkaline-phosphatase after stimulation by 1,25-dihydroxy-Vitamin D(3) up to 50% and decreased telomerase activity by up to 40%. The data demonstrate that suramin has marked in vitro effects on human osteosarcoma cells supporting further clinical investigation.

Alkaline Phosphatase↗

Osteosarcoma arising in Paget's disease of the mandible.

Although osteosarcoma is a well-known complication of Paget's disease of bone, it uncommonly develops in the jaw bones. We present an osteosarcoma arising in Paget's disease of the mandible with unique features of a normal serum alkaline phosphatase level, and histologic features of telangiectatic change in the osteosarcoma and association with cemento-osseous dysplasia. Sixteen reported cases of osteosarcoma arising in Paget's disease of the jaw bones (OPJ) are also reviewed and compared to osteosarcoma arising in Paget's disease occurring in the entire skeleton (OPS) and osteosarcoma arising de novo in the jaw bones (OJ). Females are more commonly involved in OPJ in contrast to a male predominance in OPS and OJ. OPJ also has a distinctively higher percentage involving blacks compared to OPS. The prognosis of OPJ is poor, with 69% of patients dying within two years after diagnosis. Early recognition, early and aggressive treatment are important to improve the prognosis and are hence emphasized.

Aged↗

2-methoxyestradiol induces interferon gene expression and apoptosis in osteosarcoma cells.

2-Methoxyestradiol (2-ME), a naturally occurring mammalian metabolite of 17beta-estradiol, has been implicated as a physiological inhibitor of tumor cell proliferation. In this study, the effects of 2-ME on cultured osteosarcomatous cells were investigated. Dose-dependent growth inhibition was observed in MG63 and TE85 human osteosarcoma cells exposed to 2-ME. The cell killing by 2-ME was ligand-specific; the immediate precursor (2-hydroxyestradiol), the parent compound (17beta-estradiol), and the equivalent metabolite of estrone (2-methoxyestrone) exhibited less potency and efficacy. Furthermore, 2-ME was similarly effective at killing immortalized human fetal osteoblastic cells (hFOB) with and without estrogen receptor-alpha and -beta and rat osteosarcoma cells (ROS17/2.8). The cytotoxicity of 2-ME was selective to transformed and immortalized osteoblastic cells; 2-ME (2 microm) had no effect on the proliferation of primary cultures of human osteoblasts. Co-treatment with the potent estrogen receptor ligand, ICI-182,780, did not reduce 2-ME-induced osteosarcoma cell death, implying that this action is not mediated by conventional estrogen receptors. The expression levels of bone matrix protein genes, type 1 collagen and osteonectin, were transiently reduced after 2-ME treatment, suggesting that the surviving cells are capable of producing bone matrix. The 2-ME-mediated killing of osteosarcoma cells was due to the induction of apoptosis; treatment induced expression of interferon genes within 12 h and histological evidence of apoptosis within 48 h of 2-ME treatment. Thus, our results demonstrate that 2-ME is highly cytotoxic to osteosarcoma cells but not normal osteoblasts. These findings suggest that further study of 2-ME as a potential intervention for treatment of osteosarcoma is warranted.

2-Methoxyestradiol↗

Human osteosarcomas inhibit hematopoietic colony formation: partial reversal by antibody to transforming growth factor-beta 1.

Recently we found that primary human osteoblast-like cells (HOBs) support hematopoietic progenitor cells (assayed by colony formation in methylcellulose) and long-term culture initiating (LTC-IC) activity in vitro. In the present investigation, we evaluate whether human osteosarcoma cells share in these activities. We observed that relative to controls, significantly fewer hematopoietic colonies were formed in the presence of HOS TE85, MG-63, SaOS-2, or U2-OS human osteosarcomas. In addition, neither MG-63 or SaOS-2 cells supported hematopoietic progenitor cell activity or LTC-IC activity in vitro. We established that the suppressive activity produced by the osteosarcomas is soluble, correlated with osteosarcoma cell number and is partially neutralized with antibody to TGF-beta 1,2,3. While it is clear that the osteosarcomas express several phenotypic characteristics of primary human osteoblasts, these data suggest that they may be functionally disregulated with regard to their ability to support normal hematopoiesis. For these reasons, caution should be exercised when evaluating osteoblastic and hematopoietic cell interactions based purely on the use of osteosarcoma cell lines.

Antibodies↗

Frequent reduction or loss of DCC gene expression in human osteosarcoma.

The 'deleted in colon carcinoma' (DCC) gene has been considered a candidate tumour-suppressor gene that encodes for a transmembrane protein with strong structural similarity to members of the superfamily of neural cell adhesion molecules. It has been mapped to the chromosomal region 18q21.1 and it is implicated in cellular differentiation and developmental processes. In human osteosarcoma allelic loss frequently occurs on the long arm of chromosome 18, suggesting a possible involvement of the DCC gene in the pathogenesis of this tumour entity. In the present study the mRNA and protein expression and rearrangements at the DNA level of the DCC gene were addressed in 25 osteosarcomas and several tumour cell lines, including osteosarcoma- and colon carcinoma-derived cell lines. Using an reverse transcriptase polymerase chain reach in (RT-PCR)-based approach DCC expression was found to be lost or substantially reduced in 14 of 19 high-grade osteosarcomas, in three of six lower grade osteosarcomas and most of the tumour cell lines, in contrast to normally differentiated osteoblasts. Immunohistochemical studies on DCC protein expression of 14 selected tumours correlated well with the RT-PCR-based results. In view of the putative tumour-suppressor characteristics of the DCC gene its loss or reduction of expression could be a specific event in the development or progression of many high-grade osteosarcomas.

Adolescent↗

Evaluation of the predictive value of Her-2/neu gene expression on osteosarcoma therapy in laser-microdissected paraffin-embedded tissue.

Histologic response to chemotherapy is currently the strongest prognostic factor in high-grade osteosarcoma, but it can only be assessed after several weeks of therapy. Thus, detection of chemosensitivity at the time of diagnosis would be of great clinical importance. The expression of the proto-oncogene Her-2/neu has been shown to be of predictive value in breast cancer and has also been considered as prognostic marker for osteosarcomas, but reports of mainly immunohistochemical studies are controversial. Therefore, the aim of this study was to investigate Her-2/neu gene expression in laser-microdissected osteosarcoma cells. Laser microdissection enables the precise isolation of morphological defined cells from archival tissue specimens and is in combination with the highly sensitive real-time RT-PCR technique a valuable tool for cell-specific analysis of gene expression. Through optimization of current protocols, we could show that this technique can be successfully applied on formalin-fixed, paraffin-embedded and decalcified osteosarcoma tissue with high sensitivity and reproducibility. In all 17 osteosarcoma biopsies analyzed, we could detect Her-2/neu gene expression. Expression correlated significantly with the response to preoperative chemotherapy, which was assessed histologically according to the six-grade scale of Salzer-Kuntschik. Risk assessment on the basis of increased Her-2/neu gene expression matched the histologic findings in 16 out of 17 cases (94%). These data demonstrate the reliability of laser microdissection in the analysis of gene expression and suggest a possible role of Her-2/neu as prognostic marker for therapy outcome in osteosarcomas.

Antineoplastic Agents↗