Changes in protein expression associated with chronic in vitro exposure of hexavalent chromium to osteoblasts and monocytes: a proteomic approach.

Cr (VI) is a well-recognized environmental toxin and carcinogen. It is known to be released from orthopedic metal implants in-situ by biocorrosion and is speculated to play a role in periprosthetic osteolysis. It is hence essential to understand its long-term biological effects. We have assessed the in vitro responses of osteoblasts and monocytes to chronic exposure (3 weeks) to Cr (VI), at concentrations that have been measured in patients with metal implants, using two-dimensional gel electrophoresis. Cr (VI) exposure resulted in a differential time-dependent regulation of glycolytic, stress, and cytoskeletal proteins. The proteins that have been found to be altered in expression play an essential role in normal cellular functioning such as energy metabolism, cell signaling, and proliferation. The results highlight the complex molecular changes that occur in both cell types with long-term exposure to Cr and may be useful in establishing a series of clinically useful biomarkers to monitor long-term use of metallic implants.