Unknown,Transcriptomics,Genomics,Proteomics

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Discovery of genes differentially-expressed in the endothelium of lymph nodes draining metastatic versus non-metastatic tumors

ABSTRACT: Metastasis to lymph nodes is an early and prognostically important event in the progression of many human cancers, and is associated with expression of vascular endothelial growth factor-D (VEGF-D). Changes to lymph node vasculature occur during metastasis, and may establish a metastatic niche capable of attracting and supporting tumor cells. We used microarrays to characterise the molecular profiles of endothelial cells from lymph nodes draining metastatic (VEGF-D-overexpressing) and non-metastatic tumors, and to identify differentially-expressed genes that might have therapeutic or prognostic potential. Draining lymph nodes of metastatic (VEGF-D-overexpressing) or non-metastatic tumors were pooled from 1-5 mice and enzymatically digested. Lymph nodes draining metastatic tumors were included for the analysis only if macroscopically enlarged, indicating the presence of metastatic cells. After digestion, tumor cells and leukocytes were depleted via immunomagnetic selection, and the resulting lymph node stromal cells were cultured briefly. Podoplanin was then used as a positive immunomagnetic selection marker to enrich for lymphatic and other endothelial cells in the lymph node. RNA was isolated from biological duplicate lymph node endothelial cell (LN EC) preparations and analysed by microarray.

ORGANISM(S): Mus musculus

SUBMITTER: Rae Farnsworth

PROVIDER: E-GEOD-31123 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background Breast cancer patients who present in the early stage of disease are affected by metastasis to the axillary group of lymph nodes. The first among this group that is affected is called as sentinel lymph node, and metastasis to this lymph node is crucial for the staging of cancer and the quality of surgical intervention. Sentinel Lymph Node Biopsy (SLNB) that is currently used to assess lymph node metastasis is neither sensitive, nor specific, is time-consuming, thereby necessitating the identification of novel biomarkers that can flag sentinel lymph node metastasis. Methods Breast cancer patients were screened, and those with early stage were recruited in the study. Surgical resection of the breast was followed by identification of sentinel lymph nodes by methylene fluorescent technique. Histo-pathology of fresh frozen section biopsy was used as the gold standard to assign the clinical phenotypes of metastatic (SLNM+) and non-metastatic sentinel lymph nodes (SLNM-). Discovery phase of the experiment included isobaric Tags for Relative and Absolute Quantitation (iTRAQ) technique comprising of six comparative experiments coupled with mass spectrometric analysis on Orbitrap Fusion to identify differentially expressed proteins on Proteome Discoverer 2.4. Functional enrichment and pathway analyses of differentially regulated genes was carried out in DAVID functional annotation tool. Validation was done by ELISA and protein concentrations were used to estimate the ROC for computing diagnostic parameters. Results Based on MS/MS spectra there were 2396 unique protein groups and 81 differentially expressed proteins comparing SLNB + and SLNB -. Nineteen proteins up-regulated, and eight proteins that were down regulated in SLNB+ as compared to SLNB-. Bioinformatic analysis showed the implication of extra cellular matrix proteins and ECM-receptor interaction pathways to be implicated in lymph node metastasis. ELISA confirmed the up-regulation of caveolin 1, collagen α-1, desmin, fibrillin-1, and microfibrillar associated glycoprotein 4 in metastatic, as compared to non-metastatic lymph nodes. These proteins are known to be integral in tumorogenesis, cell proliferation, invasion, cell survival and anti-apoptosis. These proteins have 80%-100%, of sensitivity and specificity to differentiate the two clinical phenotypes. Conclusion Identified extra cellular matrix protein biomarkers have requisite diagnostic parameters to be developed as a translational tool to assess the status of sentinel lymph nodes during mastectomy procedure to guide surgical therapy of axillary lymph nodes in early breast oncology.

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Discovery of genes differentially-expressed in the endothelium of lymph nodes draining metastatic versus non-metastatic tumors

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