Potential of a Novel Safety Evaluation of Nanomaterials Using a Proteomic Approach

We studied changes in protein expressions using human monoblastic leukemia cells (U937) exposed to carbon black (CB) to explore the possibility of a new safety evaluation method using a proteomic approach. The cells exposed to CB with a particle size of approximately 85 nm did not show cell growth inhibition by 96 hr. However, when we performed two-dimensional electrophoresis with U937 cell lysates four times and analyzed the get images, we found that the CB-exposed cells had changed significantly in 14 protein spots, with expression amounts being different by more than two-fold those at 96 hr. Only one protein was up-regulated while the others were down-regulated. Ten of the 14 spots were identified using peptide mass fingerprinting: transportin 1, thioredoxin domain containing 5, annexin A2, otubain 1, 14-3-3 protein gamma, etc. The functions of these proteins are associated with metabolism, responses to stress, signal transduction, and cell differentiation. According to our research, CB undoubtedly causes biological responses, but those responses are not detectable by conventional methods. Regarding safety risk, the proteomic approach could possibly detect biological responses more sensitively than conventional in vitro evaluation methods.