Expression and functional role of c-kit ligand (SCF) in human multiple myeloma cells

R. M. Lemoli, A. Fortuna, A. Grande, B. Gamberi, L. Bonsi, M. Fogli, M. Amabile, M. Cavo, S. Ferrari, S. Tura

Research output: Contribution to journalArticlepeer-review

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 SCP 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 (71 ± 2.3% of BRDU+ cells; P = 0.006), IL-3 (5.3 ± 13%; 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.

Original languageEnglish
Pages (from-to)760-769
Number of pages10
JournalBritish Journal of Haematology
Volume88
Issue number4
Publication statusPublished - 1994

Keywords

  • Autocrine-paracrine growth loop
  • Cell proliferation
  • Gene expression
  • Multiple myeloma
  • SCF

ASJC Scopus subject areas

  • Hematology

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