Serum protein expression profiling and bioinformatics analysis in workers occupationally exposed to chromium (VI)

Cr(VI) is widely-recognized as occupational and environmental contaminant, but the precise underlying mechanisms of Cr(VI) induced carcinogenic toxicity remain to be elucidated. Among kinds of toxic mechanisms, alteration of protein profiling usually elaborate a key mechanism of Cr(VI) induced toxicity and carcinogenesis. Large-scale proteins changes can reflect the onset or progression of carcinogenic toxicity, and potential serum protein biomarkers of Cr(VI) exposure. To gain an insight into the serum proteins expression profiling in chromate workers and find potential novel serum proteins biomarkers of Cr(VI) exposure, 107 male participants from a chromate production plant were recruited into the study. Questionnaire was applied to collect personal information and occupational history. Chromium concentration in blood (CrB) was measured to evaluate the participants' internal exposure. Serum proteins profiling and bioinformatics analysis were performed to explore differentially expressed proteins, proteins-chemical interaction network, critical proteins nodes related to the signaling pathways among 16 controls and 25 exposure workers in the first stage. ELISA tests were applied to verify the critical interested proteins nodes in the remaining 41 exposure workers and 25 controls. The results showed that the CrB levels in the control group were significantly lower than that in the exposure group (P < 0.05). 44 significantly differentially expressed serum proteins formed 16 significant signaling pathways and a complex proteins-chemical interaction network, which associated with the immune system and extracellular matrix organization. C reactive protein (CRP), sonic hedgehog protein (SHH) and calcium located at critical nodes in proteins-chemical interaction network. There was a significant negative correlation between serum CRP level and CrB (P < 0.05), and a significant positive correlation between SHH concentrations and CrB (P < 0.05), which indicated that CRP and SHH might be as the potential novel biomarkers of Cr(VI) exposure. Also, the current study preliminarily paved the way to further functional studies to understand the underlying mechanisms and novel serum biomarkers of Cr(VI) exposure.