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C-kit ligand (SCF) in human multiple myeloma cells
1Institute of Hematology, University of Bologna, Italy.
Abstract:
Here we review our recent experience addressing the role of SCF in multiple myeloma (MM). We first investigated the proliferation of MM cell lines and bone marrow samples from myeloma patients in response to rh-SCF alone and combined with Interleukin-6 (IL-6), IL-3, and IL-3/GM-CSF fusion protein PIXY 321. Neoplastic plasma cells were highly purified (>90%) by immunomagnetic depletion of T, myeloid, monocytoid and NK cells. The number of S-phase cells was evaluated after 3 days of liquid culture by the bromodeoxyuridine (BRDU) incorporation assay. The proliferation of RPMI 8226 and U266 cell lines was also assessed by a clonogenic assay. All the experiments were performed in serum-free conditions. RPMI 8226 cell line was not stimulated by SCF which also did not augment the proliferative activity of IL-6, IL-3 and PIXY-321. Conversely, SCF addition resulted in 2.4-fold increase of the number of U266 colonies and in a higher number of U266 and MT3 cells in S-phase. The c-kit ligand also enhanced the proliferation of MT3 and U266 cells mediated by the other cytokines. Anti-SCF polyclonal antibodies completely abrogated the proliferative response of MT3 cells to exogenous SCF and markedly reduced the spontaneous growth of the same cell line. Reverse transcriptase-polymerase chain reaction amplification (RT-PCR) did detect SCF mRNA in MT3 and RPMI 8226 cells. Moreover, secreted SCF was found, in a biologically active form, in the supernatant of the two cell lines by the MO7e proliferation assay. These results suggest that an autocrine proliferative loop may be operative in MT3 cell line. When tested on fresh myeloma samples, SCF increased the number of S-phase plasma cells (4.7 +/- 1.6% vs 3.4 +/- 1.3% in control cultures; p = 0.02). Significant proliferation was also induced by IL6, IL-3 and PIXY-321. The addition of SCF significantly enhanced the proliferation of myeloma cells responsive to IL-6. Preliminary experiments performed on circulating plasma cells and myeloma precursors further supported the role of SCF on the proliferation of the neoplastic clone in MM.
Insights
Stem cell factor (SCF) promotes multiple myeloma (MM) cell proliferation, particularly in U266 cell lines and patient samples. SCF enhances the effects of other cytokines, suggesting a role in MM growth.
Area of Science:
- Hematology
- Oncology
- Cell Biology
Background:
- Multiple myeloma (MM) is a cancer of plasma cells.
- The role of stem cell factor (SCF) in MM proliferation is not fully understood.
- Investigating SCF's impact on neoplastic plasma cells is crucial for understanding MM pathogenesis.
Purpose of the Study:
- To investigate the role of stem cell factor (SCF) in multiple myeloma (MM) cell proliferation.
- To assess SCF's effect alone and in combination with other cytokines (IL-6, IL-3, PIXY 321) on MM cell lines and patient samples.
- To determine if SCF contributes to an autocrine proliferative loop in MM.
Main Methods:
- Purification of neoplastic plasma cells (>90%) using immunomagnetic depletion.
- Assessment of cell proliferation via bromodeoxyuridine (BRDU) incorporation assay and clonogenic assays.
- Detection of SCF mRNA using reverse transcriptase-polymerase chain reaction (RT-PCR) and evaluation of secreted SCF activity.
Main Results:
- SCF significantly increased colony formation and S-phase cells in the U266 MM cell line.
- SCF enhanced the proliferative response of MT3 and U266 cells to other cytokines (IL-6, IL-3, PIXY 321).
- SCF addition significantly increased S-phase plasma cells in fresh myeloma patient samples, particularly those responsive to IL-6.
Conclusions:
- Stem cell factor (SCF) plays a significant role in promoting multiple myeloma (MM) cell proliferation.
- An autocrine proliferative loop involving SCF may be operative in certain MM cell lines (e.g., MT3).
- SCF enhances the proliferation of neoplastic plasma cells in MM patients, suggesting it as a potential therapeutic target.