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Expression of a novel 3.5-kb macrophage colony-stimulating factor transcript in human myeloma cells
M Nakamura1, S Merchav, A Carter
1Division of Tumor Immunology, Dana-Farber Cancer Institute, Boston, MA 02115.
Abstract:
Macrophage CSF (M-CSF) induces proliferation of monocyte/macrophage progenitor cells and can also activate some functions of mature cells. Three different human M-CSF cDNA (4.0, 3 to 3.5, and 1.5 kb) which are the result of alternative splicing of the single M-CSF gene have been cloned. Each of these cDNA encode a biologically active M-CSF. M-CSF transcripts are expressed in normal fibroblasts and other mesenchymal cells, and also in some hematopoietic cells such as monocytes. Normal human cells examined to date express only the 4.0-kb transcript. In contrast, a 3.5-kb M-CSF transcript was continuously expressed in two multiple myeloma cell lines (RPMI 8226 and U266/AF10) and in a bone marrow specimen of a patient with multiple myeloma. The myeloma cell lines secreted biologically active M-CSF. Resting and activated normal B lymphocytes and other B cell neoplasms examined did not express the 3.5-kb transcript, but could be induced to express the 4.0-kb transcript and to secrete M-CSF. Myeloma cells appear to be unique among hematopoietic cells in their expression of the 3.5-kb M-CSF transcript.
Insights
Multiple myeloma cells uniquely express a specific Macrophage Colony-Stimulating Factor (M-CSF) transcript. This finding highlights distinct M-CSF gene expression in myeloma, impacting cell function and potential therapeutic targets.
Area of Science:
- Molecular Biology
- Hematology
- Cancer Biology
Background:
- Macrophage Colony-Stimulating Factor (M-CSF) is crucial for monocyte/macrophage development and function.
- Alternative splicing of the M-CSF gene generates multiple transcript variants.
- M-CSF transcripts are typically found in mesenchymal and some hematopoietic cells.
Purpose of the Study:
- To investigate M-CSF transcript expression in normal human cells and multiple myeloma.
- To determine if specific M-CSF transcript variants are associated with multiple myeloma.
Main Methods:
- Cloning of three human M-CSF cDNA variants (4.0, 3.5, and 1.5 kb).
- Analysis of M-CSF transcript expression in normal fibroblasts, monocytes, B lymphocytes, and multiple myeloma cell lines (RPMI 8226, U266/AF10).
- Detection of M-CSF secretion from myeloma cell lines.
Main Results:
- All cloned M-CSF cDNA variants encode biologically active M-CSF.
- Normal human cells predominantly express the 4.0-kb M-CSF transcript.
- Multiple myeloma cell lines and a patient's bone marrow specimen showed continuous expression of the 3.5-kb M-CSF transcript.
- Myeloma cells secreted biologically active M-CSF.
Conclusions:
- Myeloma cells exhibit unique expression of the 3.5-kb M-CSF transcript among hematopoietic cells.
- This specific M-CSF transcript expression may contribute to the unique characteristics of myeloma cells.
- Further research into M-CSF in myeloma could reveal therapeutic strategies.