Determining Biological Effects Of Mobile Phone Radiation On MCF-7 Cells By Proteomics Analysis Approach

The exposure level of human to radiofrequency (RF) radiation has increased during recent years due to the rapid development of mobile communication and widespread use of mobile phone (sometimes called cell phone). Public concerns have been raised about the health effects of mobile phone use. Epidemiological studies have indicated an association between cell phone use and the risk of human cancers or non-cancer diseases (e.g., cataracts, chronic neural diseases). But an exclusive correlation has not been well established. Similarly, results of in vivo and in vitro studies are contentious and contradictory data still remain in the literature. Therefore,the RF research has been listed as a priority by WHO since 2003 (see http://www.who.int/peh-emf/research/rf03/en/).Investigating the biological effects and underlying mechanism of RF radiation will help to evaluate its health risk. Recently, high-throughput screening techniques (HTSTs) of transcriptomics and proteomics have been proposed as an ideal approach to non-selectively gather information about the efFects of environmental stimuli on cell gene transcription and protein expression. In the present study, we employed two dimensional electrophoresis (2-DE) to determine whether mobile phone radiation can change protein expression profile of human cells and find possible responding proteins.We first tried to determine an optimal protein solublization method for human breast cancer cell line MCF-7. After comparing three routine-used cellular total protein extraction reagents, i.e. M-PER kit, standard lysis buffer, and improved lysis buffer, by the indexes of protein abundance and spot distribution on corresponding silver-stained gel, we finally chose the improved lysis buffer as the relatively best method.Then, MCF-7 cells were exposed and sham-exposed to 1800 MHz modulated RF radiation (GSM) at different intensities, different modes, and different duration, including: (1) intermittent exposure at an average specific absorption rate (SAR) of 2 W/kg modulated by 217 Hz for 5 minutes followed by a 10-minute pause for total 24 h; (2) intermittent exposure (SAR=3.5 W/kg) as described in (1) for 24 h, 12 h, 6 h, 3 h and 1 h, respectively; (3) continuous exposure (SAR=3.5 W/kg) modulated by 217 Hz for 24 h, 12 h, 6 h, 3 h and 1h, respectively. After exposure, whole cellular proteins were extracted and stored in -70 ℃ freezer after determining protein concentration by Bradford assay. 200 μ g protein was subjected to 2-DE, including rehydration for 12h, IEF using 17 cm pH 4-7 linear IPG strips and SDS-PAGE by 200 volt for 7 h. Gels were silver stained and scanned by GS-800 densitometer, thenanalyzed for differential expression with sham-exposed sample without RF radiation as a control in PDQuest 7.1 software package.On the average, about 1100 protein spots were detected in each gel. Compared with sham-exposed group, ?There was no difference under intermittent exposure at an SAR of 2 W/kg modulated by 217 Hz for 5 minutes followed by a 10-minute pause for total 24 h .?There were two differential proteins detected on the intermittent exposure at an SAR of 3.5 W/kg modulated by 217 Hz for 5 minutes followed by a 10-minute pause for total 24 h. One is up-regulated (P<0.05), the other is down-regulated (PO.05). There were two differential proteins down-regulated (PO.05) under the above exposure for 12 h. There was only one protein down-regulated (P<0.05) under the above exposure for 6 h. Six proteins were absent while three proteins were up-regulated (PO.05) and nine down-regulated (PO.05) under the above exposure for 3 h. There were six proteins absent in sham-exposed group under the above exposure for 1 h. ?Two proteins showed decreased expression (PO.05) under the continuous exposure (SAR=3.5W/kg) modulated by 217 Hz for 24 h. There were two proteins absent in sham-exposed group, two proteins absent in exposed group, and three proteins up-regulated (PO.05) under the above exposure for 12 h. No differences were detected under the above exposure for 6 h. For 3 h, two proteins were down-regulated (PO.05). There were two proteins down-regulated (PO.05), and one protein absent in exposed group under the above exposure for 1 h. Data suggested that exposure to higher intensity of RF (3.5 W/kg) may change the protein expression profile slightly, and intermittent exposure induced more protein expression changes than continuous one.