LOW CONCENTRATIONS OF ZOLEDRONIC ACID PROTECT OSTEOBLASTS FROM CYTOTOXIC EFFECTS OF MULTIPLE MYELOMA CONDITIONED MEDIUM
Chigueyuki Jitumori, Giovani Marino Favero, Felipe de Lara Janz* and Elizabeth Ferreira Martinez
ABSTRACT
Multiple myeloma (MM) is a hematological disease that affects bone development. Zoledronic acid (ZA) is a bisphosphonate drug which reduces bone destruction caused by myeloma. This research aims to evaluate in vitro protective effects of zoledronic acid in osteoblasts treated with conditioned medium from MM cells. Conditioned medium (CM) was obtained from RPMI8226 cell culture. IL-6, TGF-β, VEGF and FGF analysis was performed by ELISA method. CM was added to osteoblast cell cultures at 5μl/mL, 15μl/mL, 30μl/mL and, then, ZA at 1μM, 5μM and 10μM concentrations. Cell viability was analyzed by
MTT staining; cell proliferation was evaluated by Trypan blue staining (24, 48 and 72 hours), and osteoblastic cell death was analyzed by flow cytometry (24 and 72 hours). CM presents IL-6, TGF-β, VEGF and FGF. MTT method showed that osteoblast cells were viable and presented increased cell proliferation in the presence of ZA at 1μM, 5μM and 10μM (p <0.05). Flow cytometry results showed an increasing osteoblastic cell death in presence of ZA at 15μl/mL and 30μl/mL concentrations. Cell cycle analysis demonstrated high percentage of S/G2/M in the presence of ZA (p < 0.05). We can conclude that low concentrations of ZA protect osteoblasts from MM toxic cytokines present in CM.
Keywords: Multiple Myeloma; Osteoblast; Zoledronic Acid.
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