Increased Levels of Serum Tissue Inhibitor of Metalloproteinase-1 Correlate with Advanced Stage, Increased Bone Resorption, Lytic Bone Disease and Poor Survival in Newly-Diagnosed Myeloma Patients

Tissue inhibitor of metalloproteinase-1 (TIMP-1) is a natural metalloproteinase (MMP) inhibitor that binds to and inactivates mainly MMP-9. TIMP-1 has multifunctional roles in tumorigenesis: inhibition of the catalytic activity of metalloproteinases, growth promotion, inhibition of apoptosis, and regulation of angiogenesis. Increased TIMP-1 has been associated with an unfavorable prognosis in many cancers including breast, colorectal, gastric, head and neck, lung cancer, and lymphomas. In vitro studies have revealed that TIMP-1 is overexpressed in myeloma cell lines. Furthermore, TIMP-1 promotes myeloma cell invasion across basement membranes. The aim of this study was to evaluate the serum levels of TIMP-1 in newly-diagnosed, previous untreated myeloma patients and explore possible correlations with clinical and laboratory data, including survival. Fifty-five patients with newly-diagnosed myeloma (25M/30F, median age: 69 years) were evaluated. Eleven patients had stage 1 disease according to ISS, while 27 had stage 2 and 17 stage 3 myeloma. Serum TIMP-1 was determined before the administration of any therapy, including bisphosphonates, using ELISA methodology (Oncogene Science/Siemens HealthCare Diagnostics, Cambridge, MA, USA) along with a series of serum markers of bone metabolism:

• osteoclast regulators [soluble receptor activator of nuclear factor-κB ligand (sRANKL), and osteoprotegerin (OPG)],

• osteoblast inhibitor dickkopf-1 (Dkk-1),

• bone resorption markers (N- & C-telopeptide of collagen type-I: NTX, CTX and ICTP; and tartrate-resistant acid phosphatase-isoform 5b, TRACP-5b), and

• bone formation markers (bone-specific alkaline phosphatase, bALP; and osteocalcin, OC).

The above bone markers were also evaluated in 27 healthy controls of similar age and gender. The mean serum TIMP-1 level of all patients was 431.9 ng/ml (SD 198.1 ng/ml). Twenty-six patients (17M/9F; 47%) had elevated values of TIMP-1 (upper normal limit 324 ng/ml for males and 454 ng/ml for post-menopausal women). Patients had also increased levels of Dkk-1, sRANKL, sRANKL/OPG ratio and bone resorption markers (NTX, CTX, ICTP and TRACP-5b) (p<0.01 compared with healthy controls). TIMP-1 serum levels correlated with ICTP (r=0.514, p<0.001), beta2-microglobulin (r=0.414, p<0.01), albumin (r=-0.416, p<0.01), osteocalcin (r=0.325, p=0.01), CTX (r=0.314, p=0.01), NTX (r=0.306, p=0.02), and LDH (r=0.295, p=0.03). More importantly, TIMP-1 correlated with ISS (ANOVA p=0.005). Patients with ISS 3 disease had higher levels of TIMP-1 (mean±SD 557.8±234 ng/ml) compared with those who had ISS 1 (311±90.6 ng/ml; p=0.001) or ISS 2 disease (405.5±165.6 ng/ml; p=0.021). Furthermore, patients with lytic disease (n=43) had increased levels of TIMP-1 (457.7±205 ng/ml) compared with all others (313.6±107.6 ng/ml; p=0.05). The median follow-up was 31 months and 16/55 patients have died. The median survival has not been reached yet. Patients who had TIMP-1 level of above the mean value had a median survival of 37 months, while in all others the median survival has not been reached yet (p=0.04). Our study provides evidence for the first time that increased serum levels of TIMP-1 correlate with advanced myeloma, with increased bone resorption and with increased number of osteolytic lesions. Furthermore, elevated TIMP-1 was associated with inferior survival of MM patients. These results suggest that TIMP-1 may participate in myeloma pathogenesis and support that serum TIMP-1 deserves further study to determine its predictive and prognostic potential in a larger cohort of myeloma patients.