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Detection of retinoid receptor expression patterns in canine normal lymph nodes and in nodal lymphomas
Author(s) -
Souza C. H. M.,
Valli V. E. O.,
Fan T. M.,
Vail D. M.
Publication year - 2004
Publication title -
veterinary and comparative oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 34
eISSN - 1476-5829
pISSN - 1476-5810
DOI - 10.1111/j.1476-5810.2004.0045m.x
Subject(s) - retinoid , bexarotene , retinoid x receptor , retinoid x receptor beta , retinoid x receptor alpha , biology , receptor , retinoid x receptor gamma , cancer research , lymphoma , lymphatic system , lymph , retinoic acid , pathology , immunology , nuclear receptor , cell culture , medicine , transcription factor , biochemistry , gene , genetics
Retinoids are derivatives of vitamin A, which are essential for cell growth and differentiation of a variety of cells. Retinoid activity occurs after binding to a class of nuclear receptors termed retinoic acid receptor (RAR) and retinoid X receptor (RXR). Receptor‐ligand interactions ultimately activate the transcription of target genes. Retinoids have been shown in vitro to participate in both lymphocyte activation and apoptosis. In human cancer patients, specific ligands to retinoid receptors have been approved for the treatment of T‐cell cutaneous lymphomas. The use of retinoids for the treatment of additional lymphoid malignancies, both of B and T‐cell types, has been speculated. In vitro experiments demonstrating lymphocyte apoptosis subsequent to treatment with both natural and synthetic retinoids further support the potential utility of retinoid therapy in spontaneous lymphoid malignancies. Objectives: To detect the pattern of retinoid receptor expression (RAR and RXR) and their isoforms (α, β, and γ) in normal lymph nodes and in nodal lymphomas in dogs. Methods: Immunohistochemistry was performed in tissue specimens derived from naturally occurring cases of nodal lymphomas and normal lymph nodes from dogs. Rabbit polyclonal antibodies (Santa Cruz Biotechnology), previously demonstrated to be cross‐reactive with canine tissue, were utilized to assess the expression patterns of RAR/RXR and their respective isoforms (α, β, and γ) in all pathologic and normal tissue samples evaluated. Results: Normal lymph nodes were consistently negative for all isoforms. In hyperplastic nodes, macrophages were positive for all isoforms. Lymphomas both of B and T‐cell type stained strongly positive for the isoforms RARα and RXRγ. Conclusions: A distinctive pattern of expression between lymphomas, lymphoid hyperplasia, and normal lymph nodes was detected in dogs. Different retinoid receptor expression profiles from normal lymph nodes and nodal lymphomas seem to be of diagnostic importance. Further investigation with larger number of lymphoma cases is warranted to thoroughly characterize retinoid receptor expression patterns in lymphoid malignancies with the possibility of using specific retinoid receptor ligands for the treatment of canine nodal lymphomas.