Proteomic profiling for cellular responses to different concentrations of N-methyl-N'-nitro-N-nitrosoguanidine.

Alkylating agent MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) can induce DNA damages which can lead to chromosomal aberrations, mutations, and cell death. Previous reports from our laboratory have found that low concentration of MNNG can induce nontargeted mutations (NTM) at undamaged bases in DNA, clustering of epidermal growth factor receptor (EGFR) and interference of EGFR mediated signaling, as well as activation of endoplasmic reticulum stress. Thus, the cellular responses to MNNG exposure are very complex, and can be triggered by signals originated from different compartments of the exposed cells. To further probe the molecular mechanisms involved in cellular responses to MNNG treatment, and to find potential biomarkers for MNNG induced stress condition, we performed proteomic analysis of whole cellular proteins from human amnion epithelial cells after exposing to MNNG at 3 different doses. More than 80 proteins were affected by MNNG treatment, and 71 proteins among them were identified using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. These proteins take part in a wide variety of cellular processes including regulation of transcription, metabolism, cytoskeleton organization, cell cycle, cell proliferation, signal transduction, transportation, etc. The significance of these proteins in the genesis of MNNG induced cellular defensive response and hazardous effect remains to be elucidated, the results may also give a clue for biomarker search for monitoring the exposure risk of MNNG.