The Senescence-Associated Secretory Phenotype In Multiple Myeloma

The incidence of multiple myeloma (MM) increases with age, yet some cytogenetic changes are actually more common in younger patients with MM (Avet-Loiseau J Clin Oncol 2013).  This suggests that a mechanism other than chromosomal changes underlies the increased incidence with age.  Senescent cells secrete a number of proinflammatory cytokines, chemokines, growth factors and proteases resulting in the senescence-associated secretory phenotype (SASP), which can promote tumor growth.  Preclinical data suggests that myeloma bone marrow stromal cells express the SASP (Andre PLOS ONE 2013). We hypothesized that SASP factors correlate with age in patients with MM.

Peripheral blood serum and matched bone marrow aspirate plasma from patients with multiple myeloma were evaluated for selected factors associated with the SASP using quantitative multiplex immunoassay (Rules Based Medicine, Austin TX USA).  SASP factors with a known role in MM [interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-15 (IL-15), granulocyte-macrophage colony-stimulating factor (GMCSF), intercellular adhesion molecule 1(ICAM1), osteoprotegerin (OPG), hepatocyte growth factor (HGF), insulin-like growth factor-binding protein(IGFBP-1), interleukin-1 beta (IL1b), monocyte chemotactic protein 1(MCP-1), macrophage inflammatory protein-1 alpha(MIP-1a), angiogenin, leptin,  vascular endothelial growth factor receptor 1(VEGFR1) and stem cell factor(SCF)] were selected. The relationship between age and SASP factors were analyzed using Kendall tau rank correlation coefficient.

Samples from 25 patients (each with peripheral blood serum and matched bone marrow aspirate plasma) were analyzed.  The median age was 62 (range 47 - 74). Disease states were as follows: 36% newly diagnosed/untreated, 24% pretransplant and 40% relapsed.  ISS stage included 40% stage I, 28% stage II and 32% stage III.  Three of the selected SASP factors in the peripheral blood correlated   with age:  IL-8 (Kendall Tau 0.334, p=0.027), OPG (Kendall Tau 0.289, p=0.046) and MCP-1 (Kendall Tau 0.332, p=0.022).  No SASP factors tested in the bone marrow plasma were significantly correlated with age.

We demonstrated age-associated differences in the SASP factors IL-8, OPG and MCP-1 in the peripheral blood of myeloma patients.  Future research will examine differences between patients with myeloma and age-matched controls without cancer.

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