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Expression and functional role of c-kit ligand (SCF) in human multiple myeloma cells
R M Lemoli1, A Fortuna, A Grande
1Institute of Haematology, University of Bologna, Italy.
Abstract:
In this study we investigated the proliferation of three well-documented MM lines and 10 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 and 7 d 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 (24.5 +/- 2% SEM v 14.5 +/- 1% SEM and 32 +/- 3% SEM v 21 +/- 4% SEM, respectively; P < 0.05). 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. When tested on fresh myeloma samples, SCF increased the number of S-phase plasma cells (4.7 +/- 1.6% v 3.4 +/- 1.3% in control cultures: P = 0.02). Significant proliferation was also induced by IL-6 (7 +/- 2.3% of BRDU+ cells; P = 0.006), IL-3 (5.3 +/- 1.3%; P = 0.01) and PIXY-321 (5.4 +/- 1.6%; P = 0.02). The addition of SCF significantly enhanced the proliferation of myeloma cells responsive to IL-6. In summary, our results indicate that SCF is expressed in MM cells and stimulates the proliferation of neoplastic plasma cells.
Insights
Stem cell factor (SCF) stimulates the proliferation of neoplastic plasma cells in multiple myeloma (MM). This study found SCF enhances the growth of MM cell lines and patient samples, particularly when combined with other cytokines like IL-6.
Area of Science:
- Hematology
- Oncology
- Cell Biology
Background:
- Multiple myeloma (MM) is a cancer of plasma cells.
- Understanding the factors that regulate MM cell proliferation is crucial for developing new therapies.
Purpose of the Study:
- To investigate the role of stem cell factor (SCF) in regulating the proliferation of multiple myeloma (MM) cell lines and primary patient samples.
- To assess the effect of SCF alone and in combination with other cytokines on neoplastic plasma cell growth.
Main Methods:
- Purification of neoplastic plasma cells from MM cell lines and bone marrow samples.
- Assessment of cell proliferation using bromodeoxyuridine (BRDU) incorporation assay and clonogenic assays.
- Evaluation of SCF expression and activity via RT-PCR and bioassays.
Main Results:
- SCF significantly increased the proliferation of U266 and MT3 MM cell lines, as well as primary myeloma cells.
- SCF enhanced the proliferative response of myeloma cells to Interleukin-6 (IL-6).
- SCF mRNA and biologically active SCF were detected in MM cell lines.
Conclusions:
- Stem cell factor (SCF) is expressed by and stimulates the proliferation of neoplastic plasma cells in multiple myeloma (MM).
- SCF represents a potential therapeutic target for MM treatment.