Purpose: High-grade osteosarcoma is a malignant primary bone tumor with a peak incidence in adolescence. Overall survival (OS) of patients with resectable metastatic disease is approximately 20%. The exact mechanisms of development of metastases in osteosarcoma remain unclear. Most studies focus on tumor cells, but it is increasingly evident that stroma plays an important role in tumorigenesis and metastasis. We investigated the development of metastasis by studying tumor cells and their stromal context.

Increased levels of P-glycoprotein occur in some osteosarcomas. In this study we determined the relation between P-glycoprotein status and outcome in patients with high-grade osteosarcoma. P-glycoprotein status was determined immunohistochemically in specimens of osteosarcoma of the extremities (stage II) from 92 patients who were treated with surgery and chemotherapy. The P-glycoprotein status was analyzed in relation to the length of event-free survival. The presence of increased levels of P-glycoprotein in the osteosarcoma was significantly associated with a decreased probability of remaining event-free after diagnosis (P = 0.002). In a multivariate analysis, P-glycoprotein status (P = 0.001) and the extent of tumor necrosis after preoperative chemotherapy (P = 0.04) were independent predictors of clinical outcome. The risk of adverse events was increased substantially (rate ratio, 3.37; 95 percent confidence interval, 1.60 to 7.10) among patients with increased levels of P-glycoprotein in tumor cells, as compared with patients who did not have increased levels of P-glycoprotein in tumor cells. In patients with high-grade osteosarcoma treated with surgery and chemotherapy, the presence of increased levels of P-glycoprotein in tumor cells is associated with a significantly increased risk of adverse events and is independent of the extent of necrosis after preoperative chemotherapy.

Osteosarcomas are the most common primary malignant tumors of bone and show multiple and complex genomic aberrations. miRNAs are non-coding RNAs capable of regulating gene expression at the post transcriptional level, and miRNAs and their target genes may represent novel therapeutic targets or biomarkers for osteosarcoma. In order to investigate the involvement of miRNAs in osteosarcoma development, global microarray analyses of a panel of 19 human osteosarcoma cell lines was performed. We identified 177 miRNAs that were differentially expressed in osteosarcoma cell lines relative to normal bone. Among these, miR-126/miR-126*, miR-142-3p, miR-150, miR-223, miR-486-5p and members of the miR-1/miR-133a, miR-144/miR-451, miR-195/miR-497 and miR-206/miR-133b clusters were found to be downregulated in osteosarcoma cell lines. All miRNAs in the paralogous clusters miR-17-92, miR-106b-25 and miR-106a-92 were overexpressed. Furthermore, the upregulated miRNAs included miR-9/miR-9*, miR-21*, miR-31/miR-31*, miR-196a/miR-196b, miR-374a and members of the miR-29 and miR-130/301 families. The most interesting inversely correlated miRNA/mRNA pairs in osteosarcoma cell lines included miR-9/TGFBR2 and miR-29/p85α regulatory subunit of PI3K. PTEN mRNA correlated inversely with miR-92a and members of the miR-17 and miR-130/301 families. Expression profiles of selected miRNAs were confirmed in clinical samples. A set of miRNAs, miR-1, miR-18a, miR-18b, miR-19b, miR-31, miR-126, miR-142-3p, miR-133b, miR-144, miR-195, miR-223, miR-451 and miR-497 was identified with an intermediate expression level in osteosarcoma clinical samples compared to osteoblasts and bone, which may reflect the differentiation level of osteosarcoma relative to the undifferentiated osteoblast and fully differentiated normal bone. Significance: This study provides an integrated analysis of miRNA and mRNA in osteosarcoma, and gives new insight into the complex genetic mechanisms of osteosarcoma development and progression.

The peak incidence of osteosarcoma (OMIM 259500) occurs during the pubertal growth spurt.^1-3 Osteosarcoma risk factors include tall height,^4,5 high birth-weight,^4,5 previous radiotherapy,⁶ and at least 8 established cancer predisposition syndromes,^7,8 including autosomal-dominant disorders (Li-Fraumeni syndrome [OMIM 151623],^9,10 hereditary retinoblastoma [OMIM 180200],^11,12 and Diamond-Blackfan anemia [OMIM 105650]^13,14) and autosomal-recessive disorders (primarily DNA helicase disorders,^15-18 such as Rothmund-Thomson syndrome [OMIM 268400], RAPADILINO syndrome [OMIM 266280], Werner syndrome [OMIM 277700], and Bloom syndrome [OMIM 210900]). Candidate gene and genome-wide association studies suggest that common single-nucleotide polymorphisms are also associated with osteosarcoma,^19-21 affirming a complex underlying architecture for its genetic etiology but one that appears to be weighted disproportionately toward rare variants.

Identification of new drugs is strongly needed for sarcomas. Insulin-like growth factor-I receptor (IGF-IR) was found to provide a major contribution to the malignant behavior of these tumors, therefore representing a very promising therapeutic target. In this study, we analyzed the therapeutic potential of a novel kinase inhibitor of IGF-IR, NVP-AEW541, in Ewing's sarcoma, osteosarcoma, and rhabdomyosarcoma, the three most frequent solid tumors in children and adolescents. NVP-AEW541 inhibits IGF-I-mediated receptor activation and downstream signaling. Ewing's sarcoma cells were generally found to be more sensitive to the effects of this drug compared with rhabdomyosarcoma and osteosarcoma, in agreement with the high dependency of this neoplasm to IGF-IR signaling. NVP-AEW541 induced a G₁ cell cycle block in all cells tested, whereas apoptosis was observed only in those cells that show a high level of sensitivity. Concurrent exposure of cells to NVP-AEW541 and other chemotherapeutic agents resulted in positive interactions with vincristine, actinomycin D, and ifosfamide and subadditive effects with doxorubicin and cisplatin. Accordingly, combined treatment with NVP-AEW541 and vincristine significantly inhibited tumor growth of Ewing's sarcoma xenografts in nude mice. Therefore, results encourage inclusion of this drug especially in the treatment of patients with Ewing's sarcoma. For the broadest applicability and best efficacy in sarcomas, NVP-AEW541 may be combined with vincristine, actinomycin D, and ifosfamide, three major drugs in the treatment of sarcomas.

An update on chemotherapy for osteosarcoma. . ???aop.label???. doi: 10.1517/14656566.2015.1102226