Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In antibody-directed enzyme-prodrug therapy (ADEPT), antibody-enzyme conjugates specifically activate non-toxic prodrugs in tumour tissue. The A33 cognate antigen is a promising target for immunotherapy of gastrointestinal cancers. We have explored A33-based ADEPT with carboxypeptidase A (CPA) and the prodrug, methotrexate-phenylalanine (MTX-Phe). In A33-positive SW1222 cells, the toxicity of MTX-Phe was about 3 logarithms lower compared to MTX. Preincubation with a huA33 antibody-CPA conjugate (huA33-CPA), but not with an isotypic control conjugate, rendered MTX-Phe equally toxic to MTX. No toxicity was observed in mice receiving MTX-Phe in 8-fold the LD50 of MTX. Nude mice bearing A33-positive SW1222 colon carcinoma xenografts were injected intravenously (IV) with 125I-labeled huA33-CPA. The conjugate localised to the tumour with a maximum from 6-24 h. Pre-treating these mice with excess A33 substantially reduced subsequent conjugate uptake, demonstrating immunologic specificity of tumour-uptake. Total tumour uptake and ratios of tumour over blood or normal tissues, however, were lower than with unconjugated A33. This may explain in part why no significant tumour responses were observed in xenografted mice. In summary, our results demonstrate in principle the feasibility of A33-based enzyme targeting, but they call for small recombinant antibody-enzyme constructs to facilitate tumour penetration and clearance from the bloodstream.
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PMID:Specific tumour localisation of a huA33 antibody--carboxypeptidase A conjugate and activation of methotrexate-phenylalanine. 1506 53

Exosomes are 40-100-nm-diameter nanovesicles of endocytic origin that are released from diverse cell types. To better understand the biological role of exosomes and to avoid confounding data arising from proteinaceous contaminants, it is important to work with highly purified material. Here, we describe an immunoaffinity capture method using the colon epithelial cell-specific A33 antibody to purify colorectal cancer cell (LIM1215)-derived exosomes. LC-MS/MS revealed 394 unique exosomal proteins of which 112 proteins (28%) contained signal peptides and a significant enrichment of proteins containing coiled coil, RAS, and MIRO domains. A comparative protein profiling analysis of LIM1215-, murine mast cell-, and human urine-derived exosomes revealed a subset of proteins common to all exosomes such as endosomal sorting complex required for transport (ESCRT) proteins, tetraspanins, signaling, trafficking, and cytoskeletal proteins. A conspicuous finding of this comparative analysis was the presence of host cell-specific (LIM1215 exosome) proteins such as A33, cadherin-17, carcinoembryonic antigen, epithelial cell surface antigen (EpCAM), proliferating cell nuclear antigen, epidermal growth factor receptor, mucin 13, misshapen-like kinase 1, keratin 18, mitogen-activated protein kinase 4, claudins (1, 3, and 7), centrosomal protein 55 kDa, and ephrin-B1 and -B2. Furthermore, we report the presence of the enzyme phospholipid scramblase implicated in transbilayer lipid distribution membrane remodeling. The LIM1215-specific exosomal proteins identified in this study may provide insights into colon cancer biology and potential diagnostic biomarkers.
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PMID:Proteomics analysis of A33 immunoaffinity-purified exosomes released from the human colon tumor cell line LIM1215 reveals a tissue-specific protein signature. 1983 82