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ITRAQ proteomics of sentinel lymph nodes for the identification of extra cellular matrix protein signatures that can flag metastasis in early breast cancer

ABSTRACT: 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.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Lymph Node

DISEASE(S): Breast Cancer

SUBMITTER: GURURAO HARIPRASAD

LAB HEAD: Gururao Hariprasad

PROVIDER: PXD027668 | Pride | 2022-05-01

REPOSITORIES: Pride

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Project description:Lymph node metastasis is a poor prognosis indicator in esophageal cancer. Although tumor spreading currently forms the main basis for therapy selection, the molecular mechanisms underlying the metastatic pathway remain insufficiently understood. Several studies aimed to investigate these mechanisms but focused mainly on regulatory patterns in the tumors themselves and/or the invaded lymph nodes. To date no study has yet investigated the potential changes on transcription level, which take place within the yet non-invaded niche. Here we provide a comprehensive description of these regulations in patients. In this study the transcriptomic profiles of regional lymph nodes were determined for two patient groups: patients classified as pN1 (metastasis) or pN0 (no metastasis) respectively. All investigated lymph nodes, also those from pN1 patients, were still free of metastasis. The gene expression data was obtained via microarray analysis. Top candidates were validated via PCR and immunohistochemistry. The results show that regional lymph nodes of pN1 patients differ decisively from those of pN0 patients – even before metastasis has taken place. In the pN0 group distinct immune response patterns were observed. In contrast, lymph nodes of the pN1 group exhibited a clear profile of reduced immune response and reduced proliferation, but increased apoptosis, enhanced hypoplasia and morphological conversion processes. DKK1 was the most significant gene associated with the molecular mechanisms taking place in lymph nodes of patients suffering from metastasis (pN1). We assume that the two molecular profiles observed constitute two different stages of a progressive disease. Finally we suggest that DKK1 might play an important role within the mechanisms leading to lymph node metastasis. First, samples were classified according to the principal status of the patients exhibiting (pN1 group) or non-exhibiting (pN0 group) metastasis in regional lymph nodes. The comparison of pN1 and pN0 patients should highlight the general differences in regulations that might lead to or prevent from metastasis. Second, two lymph node samples were collected from each patient, one node located close to the tumor (regional) and the second node distant to the tumor. While the distant nodes served as reference sample the regional nodes were investigated for transcriptional regulations. Key to the work presented here is that all nodes investigated were made sure to be still metastasis free, independent of the patients’ pN1/pN0 classification and of the location relative to the tumor. This should allow the identification of early changes occurring prior to metastasis homing.

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ITRAQ proteomics of sentinel lymph nodes for the identification of extra cellular matrix protein signatures that can flag metastasis in early breast cancer

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