Identification of APN/CD13 as the target antigen of FU3, a human monoclonal antibody that recognizes malignant fibrous histiocytoma

Department of Pathology, Fukuoka University School of Medicine and Hospital, Jonan-ku, Fukuoka 814-0180, Japan.
International Journal of Oncology (Impact Factor: 3.03). 05/2013; 43(1). DOI: 10.3892/ijo.2013.1940
Source: PubMed


Malignant fibrous histiocytoma (MFH), a high-grade, undifferentiated sarcoma, is highly aggressive, resistant to radiochemotherapy and associated with poor prognosis. There are no specific immunohistochemical markers for its diagnosis. The MFH cell line SFT7913 served as and immunogen for the generation of the FU3 monoclonal antibody in our laboratory. FU3 reacted strongly with MFH cells and with perivascular mesenchymal cells. In this study, we demonstrated that the antigen recognized by FU3 was identical to aminopeptidase N (APN/CD13) using FU3 immunoaffinity chromatography and N-terminal amino acid sequencing. Frequent (80%) and high-grade (>50% of cells) expression of APN/CD13 was observed in MFH, although low-grade expression was seen in some other sarcomas. Moreover, small interfering RNA (siRNA) that specifically targets APN/CD13 significantly suppressed MFH cell invasion in vitro. The newly developed monoclonal antibody FU3 specifically recognizes CD13 on MFH cells. Decreased expression of CD13, mediated by siRNA-mediated knockdown, attenuated the invasive capacity of MFH cells. Thus, results indicate that APN/CD13 could be an important diagnostic biomarker and therapeutic target for MFH.

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    ABSTRACT: Undifferentiated pleomorphic sarcoma, known as malignant fibrous histiocytoma, is a malignant neoplasm that arises in both soft tissue and bones. In 2002, the World Health Organization declassified malignant fibrous histocytoma as a formal diagnostic entity and renamed it 'undifferentiated pleomorphic sarcoma not otherwise specified.' It most commonly occurs in the lower extremities and rarely metastasizes cutaneously. We report a case of cutaneous metastatic undifferentiated pleomorphic sarcoma of the buttocks occurring in a 73-year-old man diagnosed with mediastinal sarcoma 4 years previously. He first noticed the mass approximately 2 months previously. Histological findings with immunomarkers led to a final diagnosis of cutaneous metastatic sarcoma from mediastinal undifferentiated pleomorphic sarcoma.
    Full-text · Article · Jun 2015 · Annals of Dermatology