Growth- and differentiation-associated expression of bcl-2 in B-chronic lymphocytic leukemia cells
| Autor: | Schena M, Lg, Larsson, Gottardi D, Gianluca GAIDANO, Carlsson M, Nilsson K, Caligaris-Cappio F |
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| Rok vydání: | 1992 |
| Předmět: |
Male
B-Lymphocytes Immunology Gene Expression Cell Biology Hematology Middle Aged CD5 Antigens Lymphocyte Activation Immunohistochemistry Leukemia Lymphocytic Chronic B-Cell Biochemistry Gene Expression Regulation Neoplastic Immunoglobulin M Proto-Oncogene Proteins c-bcl-2 Antigens CD Proto-Oncogene Proteins hemic and lymphatic diseases Humans Tetradecanoylphorbol Acetate Female RNA Messenger Cell Division Aged |
| Zdroj: | Università degli Studi del Piemonte Orientale-IRIS Europe PubMed Central |
| ISSN: | 1528-0020 0006-4971 |
| DOI: | 10.1182/blood.v79.11.2981.bloodjournal79112981 |
| Popis: | The bcl-2 gene is translocated into the Ig loci in about 80% of human follicular lymphomas and in 10% of B-type chronic lymphocytic leukemias (B-CLL), resulting in a high level of expression. We have compared the expression of bcl-2 transcripts and protein in B-CLL cells in their normal equivalent CD5+ B cells and in normal B-cell populations representative of different in vivo and in vitro stages of activation and proliferation. We report here that bcl-2 was expressed in 11 of 11 cases of CD5+ B-CLL clones, contrasting with the absent expression in normal CD5+ B cells. Activation of 173 and 183 B-CLL cells by phorbol esters (12-O-tetradecanoylphorbol-13-acetate [TPA]) to IgM secretion without concomitant DNA synthesis resulted in a rapid but transient downregulation of bcl-2 expression. In contrast, the reduction of bcl-2 at both the messenger RNA and protein levels was sustained after mitogenic stimulation, suggesting that bcl-2 expression and proliferation are inversely related in these cells. This notion was further supported by immunocytochemical analysis showing that bcl-2 was primarily expressed in small resting lymphocytes and in cells differentiating to the plasma cell stage, but less expressed in Ki67- positive proliferating B blasts. Moreover, it was also supported by the low level of bcl-2 in exponentially growing Epstein-Barr virus-carrying lymphoblastoid and B-CLL cell lines. The regulation of bcl-2 expression in B-CLL resembled that of normal tonsillar follicular B cells, in which a high level of expression was found in resting mantle zone B cells but not in the proliferating germinal center B cells. Based on these findings and the role of bcl-2 in maintaining B-cell memory, we propose that the phenotype of B-CLL cells corresponds to a mantle zone memory-type B cell. |
| Databáze: | OpenAIRE |
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