Mechanism Of PiRNAs On Prostate Proliferation Of Male Offspring After Microcystin(MC-LR) Exposure

Background:Microcystin-leucine arginine(MC-LR)could disrupt prostate development and cause prostate hyperplasia.But whether and how maternal and beforeweaning MC-LR exposure causes prostate hyperplasia in male offspring by changing expression profile of P-element-induced wimpy(PIWI)-interacting RNAs(piRNAs)have not yet been reported.Objective:The present study was aim to investigate the effect of MC-LR exposure during embryonic lactation on the expression profile of piRNAs in mouse prostate;and to clarify the mechanism by which piRNAs participated in toxicity of MC-LR on prostate.Methods:From the 12th day in the embryonic period to the 21st day after offspring birth,3 groups of pregnant mice that were randomly assigned were exposed to 0,10,and 50μg/L of MC-LR through drinking water followed by the analyses of their male offspring.Abortion rate and litter size of maternal mice were recorded.The prostate histopathology was observed.Differential expressed piRNAs of prostate were screened by piRNA microarray analysis.Murine prostate cancer cell line(RM-1)was used for further mechanism study.Luciferase report assay was used to determine the relationship between piRNA-DQ722010 and Pik3r3.Results:The down-regulated expression of piRNA-DQ722010 was the most significant in piRNA microarray analysis in 10 μg/L MC-LR treated group,while Pik3r3 was significantly up-regulated,consistent with the results that a distinct prostatic epithelial hyperplasia was observed and PI3K/AKT signaling pathway was activated.Pik3r3 was verified as the target gene of piRNA-DQ722010.In addition,we found MCLR decreased the expression of PIWI-like RNA-mediated gene silencing 2(Piwil2)and 4(Piwil4)both in vivo and in vitro,and both Piwil4 and Piwil2 could regulate the expression of DQ722010.Conclusion:MC-LR caused down-regulation of piRNA-DQ722010 and PIWI proteins,while piRNA-DQ722010 down-regulation promoted activation of PI3K/AKT signaling pathway inducing prostate hyperplasia by up-regulating the expression of Pik3r3.On the other hand,piRNA-DQ722010 down-regulation may be attributed to PIWI proteins down-regulation.Features and innovations in this study1.We observed the prostate hyperplasia in male offspring after the maternal mice were exposed to MC-LR during fetal and lactational periods.2.Expression level of piRNAs and PIWI proteins are associated with MC-LR exposure and they were down regulated in male offspring prostate after MC-LR treatment.3.piR-DQ722010 could target the 3’UTR of Pik3r3 mRNA and one of the possible mechanism by which MC-LR promoted the prostate hyperplasia is that decrease of DQ722010 activated PI3K/AKT signaling pathway and then affected cell cycle,cell proliferation and cell apoptosis.