Clinical Significance of Serum Osteopontin in Patients with Multiple Myeloma

Abstract

Angiogenesis and osteoclastogenesis are increased in the bone marrow of multiple myeloma (MM) patients in parallel with the tumor progression. Osteopontin (OPN) is a multifunctional protein that is involved in angiogenesis and bone destruction and, eventually, in tumor progression in MM. OPN is known to increase in MM patients as the disease progresses and bone is destroyed. We studied the clinical usefulness of OPN as a monitoring marker for treatment response in patients with MM. We obtained 70 serial sera from 27 MM patients and 14 sera from healthy individuals. OPN was measured by a sandwich ELISA method. The hospital records were reviewed, and the clinically important markers for monitoring the treatment response, such as monoclonal component, immunoglobulin, free light chain, and hemoglobin, etc, were analyzed together with OPN levels. There was no significant difference in OPN levels between MM patients and healthy controls. OPN showed no significant correlations with the markers used for monitoring of treatment response such as M component, immunoglobulin, and free light chain levels. There was no difference in OPN levels between the 3 groups classified by the amount of M component. In addition, OPN levels showed no compatible changes to the treatment response of MM patients. Although OPN has been known to have an important role in the formation and progression of MM by involving angiogenesis and bone destruction, our results show that OPN is not valuable as a clinical marker for monitoring the treatment response in MM patients because of inconsistency in its levels in MM patients.