Monokine Induced by Interferon-γ (MIG) Serum Levels Are a Marker of Disease Load and Correlate with Prognosis in Multiple Myeloma.

Abstract

Background and Aims: Monokine-induced by interferon-γ (MIG) is a chemokine that is produced by monocytes and macrophages in response to interferon-γ and acts as a chemoattractant mainly to T-lymphocytes in inflammatory processes. MIG has also been suggested to act in an autocrine loop to stimulate tumour cells through its receptor CXCR3, which is known to be expressed in myeloma cells. However, it is presently unclear if MIG is of biologic significance in myeloma in vivo. We have recently shown that multiple myeloma oncogene 1 (MUM1) expression in myeloma cells correlates with prognosis in this disease (Heintel D et al., ASH 2005), and MUM1 was found to upregulate MIG gene expression in B cell malignancies (Uranishi M et al., Leukemia 2005). This led us to evaluate the potential prognostic significance of MIG serum levels in a series of well characterized myeloma patients. Methods: 105 newly diagnosed multiple myeloma patients (median age 69.3 years, range 39.4–90.5) were enrolled. 18 patients presented with Durie/Salmon stage I disease, 9 had stage II and 78 had stage III. MIG serum levels were determined by a commercially available ELISA (R&D Systems). Serum samples from 17 MGUS patients and 37 age-matched healthy volunteers were used as controls. Results: MIG serum levels were elevated in multiple myeloma patients (median 161.3 pg/ml, range 9.37–1966.0) compared to MGUS patients (median 92.7 pg/ml, range 6.29–1303.1) and healthy controls (median 106.2 pg/ml, range 51.0–390.6). For analysis of myeloma cases, a cut-off level for MIG of 200pg/ml (=95th percentile of MIG in controls) was chosen to identify low and high MIG expressers. Using the cut-off as defined above, 63 patients with low MIG serum levels and 42 high MIG expressers were identified in a population of 105 myeloma patients. MIG serum levels in myeloma patients showed strong correlations with several markers of tumour load including low albumin and high β2-microglobulin. Interestingly, no correlation was found with C-reactive protein levels, indicating that MIG is not associated with an inflammatory response in myeloma. Median survival was significantly shorter in patients with high MIG serum levels compared to patients with low MIG expression (median not reached vs. 17.0 months, p<0.001; see figure). Conclusions: MIG serum levels correlate with markers of disease burden in myeloma and high MIG levels are associated with a poor outcome in this disease. Overall Survival: low vs. high MIG serum levels Overall Survival: low vs. high MIG serum levels