An approach for the identification of targets specific to bone metastasis using cancer genes interactome and gene ontology analysis

Metastasis is one of the most enigmatic aspects of cancer pathogenesis and is a major cause of cancer-associated mortality. Secondary bone cancer (SBC) is a complex disease caused by metastasis of tumor cells from their primary site and is characterized by intricate interplay of molecular interactions. Identification of targets for multifactorial diseases such as SBC, the most frequent complication of breast and prostate cancers, is a challenge. Towards achieving our aim of identification of targets specific to SBC, we constructed a 'Cancer Genes Network', a representative protein interactome of cancer genes. Using graph theoretical methods, we obtained a set of key genes that are relevant for generic mechanisms of cancers and have a role in biological essentiality. We also compiled a curated dataset of 391 SBC genes from published literature which serves as a basis of ontological correlates of secondary bone cancer. Building on these results, we implement a strategy based on generic cancer genes, SBC genes and gene ontology enrichment method, to obtain a set of targets that are specific to bone metastasis. Through this study, we present an approach for probing one of the major complications in cancers, namely, metastasis. The results on genes that play generic roles in cancer phenotype, obtained by network analysis of 'Cancer Genes Network', have broader implications in understanding the role of molecular regulators in mechanisms of cancers. Specifically, our study provides a set of potential targets that are of ontological and regulatory relevance to secondary bone cancer.Comment: 54 pages (19 pages main text; 11 Figures; 26 pages of supplementary information). Revised after critical reviews. Accepted for Publication in PLoS ON

Gene expression profiling of canine osteosarcoma reveals genes associated with short and long survival times

<p>Abstract</p> <p>Background</p> <p>Gene expression profiling of spontaneous tumors in the dog offers a unique translational opportunity to identify prognostic biomarkers and signaling pathways that are common to both canine and human. Osteosarcoma (OS) accounts for approximately 80% of all malignant bone tumors in the dog. Canine OS are highly comparable with their human counterpart with respect to histology, high metastatic rate and poor long-term survival. This study investigates the prognostic gene profile among thirty-two primary canine OS using canine specific cDNA microarrays representing 20,313 genes to identify genes and cellular signaling pathways associated with survival. This, the first report of its kind in dogs with OS, also demonstrates the advantages of cross-species comparison with human OS.</p> <p>Results</p> <p>The 32 tumors were classified into two prognostic groups based on survival time (ST). They were defined as short survivors (dogs with poor prognosis: surviving fewer than 6 months) and long survivors (dogs with better prognosis: surviving 6 months or longer). Fifty-one transcripts were found to be differentially expressed, with common upregulation of these genes in the short survivors. The overexpressed genes in short survivors are associated with possible roles in proliferation, drug resistance or metastasis. Several deregulated pathways identified in the present study, including Wnt signaling, Integrin signaling and Chemokine/cytokine signaling are comparable to the pathway analysis conducted on human OS gene profiles, emphasizing the value of the dog as an excellent model for humans.</p> <p>Conclusion</p> <p>A molecular-based method for discrimination of outcome for short and long survivors is useful for future prognostic stratification at initial diagnosis, where genes and pathways associated with cell cycle/proliferation, drug resistance and metastasis could be potential targets for diagnosis and therapy. The similarities between human and canine OS makes the dog a suitable pre-clinical model for future 'novel' therapeutic approaches where the current research has provided new insights on prognostic genes, molecular pathways and mechanisms involved in OS pathogenesis and disease progression.</p

Glucose transporter-1 expression and the antiproliferative effects of 2-deoxy-d-glucose in osteosarcoma models

2010 Summer.Includes bibliographic references (pages 34-37).Osteosarcoma (OSA) is the most common bone tumor in the dog, more common in large to giant breed dogs. 90% of dogs diagnosed with OSA will die of metastatic disease within one year of diagnosis. There have been no great advances in therapy for canine OSA over the last 20 years. Hypoxia in tumors has been associated with an increased resistance to radiation and chemotherapy, and increased metastatic potential. Hypoxia-inducible factor 1-a (HIF-la) is a transcription factor stabilized by hypoxia. Glucose transporter 1 (GLUT-1), a downstream product of HIF-la pathway activation, is over-expressed in a variety of human tumors. We sought to determine if GLUT-1 is expressed in canine OSA and if expression is related to tumor necrosis and outcome. Immunohistochemistry was performed on 44 histologically confirmed OSA tissue samples to assess expression of GLUT-1. Of 44 cases, 27 (61%) expressed GLUT-1. There was no statistical correlation between GLUT-1 and disease-free interval, survival time, or percent necrosis. As hypothesized, GLUT-1 is present in most canine appendicular OSA. A more objective evaluation of GLUT-1 and other proteins in the HIF-la pathway may be warranted. Some cells within a tumor may be poorly perfused, and therefore less susceptible to traditional chemotherapy. Cancer cells, especially those hypoxic cells that are distant from the stromal blood vessels, require more glucose than normal cells as they utilize anaerobic glycolysis, rather than oxidative phosphorylation, to survive. 2-deoxy-Dglucose (2-DG) is a glucose analog that is preferentially captured by cancer cells, _ blocking the first step of glycolysis. We evaluated the sensitivity of various OSA (canine and murine) cell lines to 2-DG, and attempted correlation to the protein GLUT-1 with western analysis. There was no statistical correlation between 2-DG and GLUT-1 or Akt expression, although it did correlate with total ERK expression. In a murine OSA model, 2-DG was shown to inhibit metastasis, possibly through the inhibition of invasion and migration, as assessed by Boyden chamber assays in vitro using the same OSA murine cell line