Hormesis Of Cell Proliferation In L929Cell Stimulated By Low Dose CdCL2

Objective:Study whether hormesis effect of the L929cell proliferation could be stimulatedby CdCL2; Determine the hormetic zone of CdCL2; Explore the mechanism and thesafety of hormesis effect, investigate the safe dose of CdCL2.Methods:1Use the colorimetric MTT method to observe whether cell proliferation hormesiseffect could be stimulated by a serial dose of CdCL2in24h exposure; Determinethe hormetic zone of the cell proliferation.2Use oxidase method to detect the activity of superoxide dismutase (SOD) in L929cell, which was stimulated by a serial dose of CdCL2in12h and24h exposure.3Use fluorescence quantitative PCR method to detect the expression of STAT3、P53、BCL-2、REVL3, which is exposed by a serial dose of CdCL2in24h.Results:1In the MTT assay, below the dose of2μmol/L, the cell proliferation is as same asthat in control group, there is no statistic significance (p>0.05). The cellproliferation of2μmol/L～15μmol/L dose group is much higher than that in thecontrol group, there is significant difference (p <0.05) between them. It showshormesis effect. About the dose larger than20μmol/L, the cells proliferation isless than that of the control group，which displays cytotoxicity.2In the xanthine oxidase assay, the relative activity of superoxide dismutasedisplays an inverted u-shaped dose-response effect after exposed to CdCL2in12hand24h. When the dose is less than2μmol/L, the activity of superoxide dismutaseis higher than that in the control group. The activity of superoxide dismutase isless than that in the control group at the dose of20μmol/L.3In the Florescent real-time quantitative PCR assay (RT-PCR), the expression ofSTAT3gene、P53gene、REVL3gene、BCL-2gene is higher than that in controlgroup at the dose of0.01μmol/L～15μmol/L. However, the expression amount to the highest at the dose of5μmol/L. The expression at the dose of20μmol/L is lessthan that in the control group, as well as the cell proliferation rate outcome. Onthe whole, the expression increases at first then goes down in the dose range from0.01μmol/L to20μmol/L.Conclusion:1CdCL2could stimulate the L929cell proliferation hormesis effect in the doserange from2μmol/L to15μmol/L. It is possible to make use of MTT assay tomeasure the hormesis of cell proliferation. When the dose is above20μmol/L, theL929cell proliferation rate is less than that of the control group because of highlevel of ROS.2The proliferation hormesis effect stimulated by CdCL2may not be a beneficialeffect for L929. It is not a safe dose range from2μmol/L to15μmol/L. The dosethat promotes the cell proliferation could induce a high level of ROS. The cell hasto produce more SOD to clear away the ROS. When the SOD level goes down, itmeans the L929cell has been suffering from an adverse effect already.2At the dose of0.01μmol/L～15μmol/L, Expression of proto-oncogene STAT3increases greatly, It is likely that an oxidative stress process changes the signalingpathways in cell, which may be related to the acceleration of cell proliferation andpromot the formation of tumor. The tumor suppressor gene P53express greatly,because the dose of CdCL2have caused damage to DNA, so the P53gene try tostop the cell cycle in order to get more time to repair the damaged DNA; TheREVL3gene expression increase in order to restore the damaged DNA, howeverthe repair process is not completely, which may cause accumulation of DNAmutation; BCL-2gene expression increased, which will interfere the function ofP53and extend the life span of the cell with damaged DNA.