Proteolytic Activity of Human Lymphoid Tumor Cells. Correlation with Tumor Progression

Matrix metalloproteinase (MMP) expression and production are associated with advanced-stage tumor and contribute to tumor progression, invasion and metastases. The current study was designed to determine the expression and production of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) by human lymphoid tumor cells. Changes in expression and production were also investigated during tumor progression of multiple myeloma and mycosis fungoides. In situ hybridization analysis revealed that lymphoblastic leukemia B cells (SB cell line), multiple myeloma (MM) cells (U266 cell line) and lymphoblastic leukemia T cells (CEM and Jurkat cell lines) express constitutively the mRNA for MMP-2 and/or MMP-9. We demonstrated by gelatin-zymography of cell culture medium that both enzymes were secreted in their cleaved (activated) form. In situ hybridization of bone marrow plasma cells and gelatin- zymography of the medium showed that patients with active MM (diagnosis, relapse, leukemic progression) express higher levels of MMP-2 mRNA and protein than patients with non-active MM (complete/objective response, plateau) and with monoclonal gammopathies of undetermined significance (MGUS). MMP-9 expression and secretion was similar in all patient groups. In patients with mycosis fungoides (MF), the expression of MMP-2 and MMP-9 mRNAs was significantly upregulated with advancing stage, in terms of lesions both positive for one of two mRNAs and with the greatest intensity of expression. Besides MF cells, the MMP-2 and/or MMP-9 mRNAs were expressed by some stromal cell populations (microvascular endothelial cells, fibroblasts, macrophages), suggesting that these cells cooperate in the process of tumor invasion. Our studies identify MMPs as an important class of proteinases involved in the extracellular matrix (ECM) degradation by human lymphoid tumors, and suggest that MMPs inhibitors may lead to important new treatment for their control

Identification of an antigenic and immunogenic motif expressed by two 7-Mer Rituximab-specific cyclic peptides. Journal of Immunology

Two 7-mer cyclic peptides, bearing the antigenic motif recognized by the anti-CD20 mAb Rituximab and differing because of motif-surrounding amino acids, inhibit the binding of Rituximab to raft-associated CD20 and Rituximab-induced membrane ceramide on human lymphoid DAUDI cells. These peptides displayed different immunogenic profiles, in that antibodies recognizing CD20 were induced in two and five out of five BALB/c mice immunized with Rp-15-C and Rp13-C respectively. Analysis of immunogenic motif, performed by panning a 7-mer phage display peptide library with purified anti-peptide IgGs, showed that the motif defined by anti-Rp15-C mostly included amino acids surrounding the Rituximab-specific antigenic motif "ANPS", whereas that defined by anti-Rp13-C was "NPS". These data showed that the motif-surrounding amino acids can markedly influence the specificity of antibodies, even when elicited with a short 7-mer peptide. Since anti-peptides antibodies analyzed are IgG, their specificity is likely to reflect how peptides are processed at the T cell level and suggests that, within a short peptide, the motif defined by T cells during the recognition phase may be different from that recognized by these cells upon their stimulation. Our findings can explain the failure of most peptide-based immunotherapy in cancer and autoimmune diseases and suggest strategies to implement the specificity of peptides-induced antibodies against the target antige