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Metastatic and Nonmetastatic canine soft tissue sarcoma comparison

ABSTRACT: We hypothesize that there is a gene signature which will improve our ability to predict development of metastatic disease in STS patients. The objective of this study was to determine the feasibility of using cDNA microarray and quantitative real-time PCR (qRT-PCR) analysis to determine gene expression patterns in metastatic versus non-metastatic canine STSs, given the inherent heterogeneity of this group of tumors. Five STSs from dogs with metastatic disease were evaluated in comparison to eight STSs from dogs without metastasis. Tumor RNA was extracted, processed and labeled for application to the Affymetrix Canine Genechip 2.0 Array. Array fluorescence was normalized using D-Chip software and data analysis was performed with JMP/Genomics. Differential gene expression was validated using qRT-PCR. Over 200 genes were differentially expressed at a false discovery rate of 5%. Differential gene expression was validated for five genes upregulated in metastatic tumors. Quantitative RT-PCR confirmed increased relative expression of all five genes of interest in the metastatic STSs. Our results demonstrate that microarray and qRT-PCR are feasible methods for comparing gene signatures in canine STSs. Further evaluation of differences in gene expression between metastatic and non-metastatic STSs is likely to identify genes important in the development of metastatic disease and improve our ability to prognosticate for individual patients.

ORGANISM(S): Canis lupus familiaris

PROVIDER: GSE24601 | GEO | 2011/02/01

SECONDARY ACCESSION(S): PRJNA132393

REPOSITORIES: GEO

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Project description:T-cells play a crucial role in canine immunoregulation and defence against invading pathogens. Proliferation is fundamental to T-cell differentiation, homeostasis and immune response. Initiation of proliferation following receptor mediated stimuli requires a temporally programmed gene response that can be identified as immediate-early, mid- and late phases. The immediate-early response genes in T-cell activation engage the cell cycle machinery and promote subsequent gene activation events. Genes involved in this immediate-early response in dogs are yet to be identified. The present study was undertaken to characterize the early T-cell gene response in dogs to improve understanding of the genetic mechanisms regulating immune function. Gene expression profiles were characterized using canine gene expression microarrays and quantitative reverse transcription PCR (qRT-PCR), and paired samples from eleven dogs. Significant functional annotation clusters were identified following stimulation with phytohemagluttinin (PHA) (5μg/ml), including the Toll-like receptor signaling pathway and phosphorylation pathways. Using strict statistical criteria, 13 individual genes were found to be differentially expressed, nine of which have ontologies that relate to proliferation and cell cycle control. These included, prostaglandin-endoperoxide synthase 2 (PTGS2/COX2), early growth response 1 (EGR1), growth arrest and DNA damage-inducible gene (GADD45B), phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1), V-FOS FBJ murine osteosarcoma viral oncogene homolog (FOS), early growth response 2 (EGR2), hemogen (HEMGN), polo-like kinase 2 (PLK2) and polo-like kinase 3 (PLK3). Differential gene expression was re-examined using qRT-PCR, which confirmed that EGR1, EGR2, PMAIP1, PTGS2, FOS and GADD45B were significantly upregulated in stimulated cells and ALAS2 downregulated. PTGS2 and EGR1 showed the highest levels of response in these dogs. Both of these genes are involved in cell cycle regulation. This study provides a comprehensive analysis of the early T-cell gene response to activation in dogs.

Project description:Proliferation, dedifferentiation, loss of cell-cell contacts and angiogenesis are among the first steps of the metastasis cascade. The complex molecular pathways associated with these events in canine mammary tumors are mostly unknown and the value of this spontaneous canine tumor as a comparative model for human breast cancer is therefore still under debate. Messenger RNA profiles of lymph-node positive canine mammary carcinomas and normal mammary glands of the same dogs were compared by microarray analysis to elucidate molecular pathways associated with metastatic progression. Differential gene expression was analyzed by gene set enrichment and pathway analysis and compared with the gene expression data of human breast cancer. Metastatic canine carcinomas had 1,312 significantly differentially expressed genes when compared to the corresponding normal mammary gland. This expression profile included a significantly increased expression of cell division and extracellular matrix invasion genes (MMP1, MMP11, MMP13, SERPINE1, TFPI2, TIMP3). In contrast, genes associated with epithelial differentiation (EGF, EGFR, KRT17, MAP2K6, STAT5), cell adhesion (CLDN5, CLDN8, CTNNAL1, MCAM, MUC1, PECAM1) and angiogenesis (ANGPT2, ANGPTL1, ANGPTL2, ANGPTL4, FGFR1, FIGF, TIE1) were mostly down-regulated. Interestingly, tumors had a significant decrease in membrane receptors and growth factor pathway gene expression (EGFR, FGFR1, GHR, LYVE1, PDGFR, PDGFR, TGFBR, TIE1), indicating a potential independence from these proliferative stimuli. Several of the identified deregulated pathways overlap with gene expression profiles of human breast cancer. Gene expression profiling of metastatic carcinomas therefore identified complex molecular pathways and functional gene families that are deregulated during malignant progression in the tumors. This study provides new insights into canine mammary tumor metastasis and suggests that canine mammary tumors may serve as a valuable model for the human disease. 13 simple mammary carcinomas with lymph node metastases at the time of tumor resection were compared with the non-neoplastic mammary gland of the same dogs. Sufficient amounts of normal mammary gland were not available for dogs no. 1 (822) and 9 (61). In addition, one normal sample without matching tumor sample was analyzed (no. 8; 2609). All patients had no radiographically detectable pulmonary metastases at the time of tumor resection. Postoperative survival was analyzed by bi-yearly telephone interviews with the owners or the attending veterinarian. Distant metastases as the cause of death were determined postoperatively by radiographic detection of metastases (nos. 1-7, 9-12) or necropsy (nos. 13 and 14). Necropsy was not authorized by the owners of dogs nos. 1-7 and 9-12. Tissue specimens of tumors and lymph node metastases were fixed in neutral-buffered 4% formalin or snap frozen in liquid nitrogen within 15 minutes after resection and stored at -80ºC until further use. Formalin-fixed tumor tissue samples were routinely embedded in paraffin and sections of 2-μm thickness were mounted on adhesive glass slides and stained with hematoxylin and eosin. Tumors and lymph nodes were evaluated histologically independently by two board-certified pathologists, following the criteria of the WHO classification of canine mammary tumors (Misdorp et al. 1999).

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Metastatic and Nonmetastatic canine soft tissue sarcoma comparison

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