Loss of CYR61 in Myeloma Microenvironment Is Associated with Poor Survival

Abstract 1813 Previously, we used gene expression profiling (GEP) on whole-bone biopsies (BX) and plasma cells (PCs) of newly diagnosed multiple myeloma (MM) patients and age-matched controls to identify 62 non-PC-related genes that were significantly differentially expressed in bone biopsies of MM. CYR61/CCN1 was the most significantly overexpressed gene in BX in subsets of MGUS and MM patients. We hypothesize that alteration of the microenvironment may be central to the conversion of MGUS to MM and that abnormal expression of CYR61 may precede this conversion. CYR61 has been shown to promote proliferation, migration, adhesion and angiogenesis and is expressed in many cell types. Within the bone, CYR61 is induced during osteoblast differentiation by endothelin-1, (Clines et al., 2007) and by Wnt3a (Si et al., 2006). CYR61 also inhibits the formation of multinucleate osteoclasts in vitro (Crockett et al., 2007). To investigate the role of CYR61 in MM pathogenesis CYR61 protein production in MM was analyzed in sera of 192 newly diagnosed myeloma patients by ELISA. In agreement with that observed by GEP, CYR61 is significantly elevated in a subset of MM patients (144/192) at diagnosis compared with healthy donors ( p p p p p SFRP2 (4.1-fold), a Wnt inhibitor, and COL2A1 (3.5-fold) which are associated with myeloma bone disease and osteoarthritis, respectively. SFRP2 is also elevated (4.3-fold) in MMPCs (194 probesets elevated) along with TNFSF10 (2.1-fold) indicative of the HY subtype and FGFR3 (2.1-fold) which is elevated in the MS subtype. In patients with high CYR61, many muscle-specific genes were elevated in MM BX and may indicate a predominance of osteocytes. Additionally, BGLAP , whose loss is associated with poor survival in myeloma, is elevated (2-fold) in MM BX (171 probesets) with high CYR61 and EDN1 , an activator of CYR61 /CCN1, is elevated (2.8-fold) in MM PCs (111 probesets) with high CYR61. The test the effect of CYR61 on cell growth, H929 cells were exposed to rCYR61 which caused a dose- and time-dependent suppression of cell growth and survival. To examine the role of CYR61 in the MM ME, H929 cells transduced with empty vector, wild type CYR61 or CYR61 cDNA with a mutated α v β 3 binding site were injected into implanted bones in SCID-hu mice. CYR61-induced effects on bone have been shown to be mediated by the α v β 3 integrin, presumably through osteoblasts. X-rays of the implanted bone and serum measurement of hIg levels were taken weekly for 5 weeks. Quantitation of change in bone mineral density (BMD) over the course of the experiment showed that CYR61 inhibits osteolysis (p v β 3 attenuates this effect. These data indicate that the α v β 3 integrin mediates CYR61-induced inhibition of osteolysis in MM. Additionally, quantitation of serum hIg demonstrated that CYR61 significantly reduces MM tumor growth (p v b 3 binding site. Taken together these data suggest that loss of CYR61 in myeloma may be indicative of a dysfunctional ME and thus serve as a biomarker to monitor the MM ME. Finally, therapeutics that upregulate CCN1 will be tested as a novel treatment for myeloma bone disease. Disclosures: Shaughnessy: Myeloma Health, Celgene, Genzyme, Novartis: Consultancy, Employment, Equity Ownership, Honoraria, Patents & Royalties.