The Effect Of Exosomal MiR-221 Derived From Hydroquinone-transformed Human Bronchial Epithelial Cells On The Proliferation Of Recipient Cells

BackgroundEpigenetics is a genetic phenomenon in which the nucleotide sequence of a gene does not change,but the phenotype changes.Epigenetics is the frontier and hot spot in the field of life science,and it is a new subject growing up rapidly in the post-genome era.The information of epigenetic not only plays an important role in the regulation of human normal growth and development,but also plays an important role in the regulation of many phenomena of diseases and the health effects of environmental pollutants.Among many ways of epigenetic regulation,miRNA is an important one.MiRNA is a class of short stranded RNA molecule with length of 19-25 nt,which belongs to highly conserved non-coding RNAs.Through complementary binding with the target gene,miRNAs can specifically and efficiently block the expression of specific gene in vivo by promoting the cleavage or degradation of specific gene mRNAs,so miRNAs can regulate gene expression at the level of post-transcription.The occurrence of cancer has been proved to be related to the abnormal expression of miRNAs.For example,the toxicity of environmental exogenous pollutants is accompanied by abnormal expression of miRNAs.Exosomes is a class of vesicular body with a typical double membrane structure with a diameter of 30-100 nm.It widely exists in peripheral blood,urine,saliva and many other body fluids.Exosomes participate in the intercellular communication between cells,and play an important role in many physiological and pathological processes.Exosomes enrich in mRNAs,noncoding RNAs,proteins and other bioactive molecules,which are important carriers of intercellular information transfer,especially in the process of occurrence and development of various diseases.Disease-related signal molecules can enter the recipient cells through exosomes.Their biological effects are involved in the occurrence and development of diseases,the sensitivity to drugs and the outcome of diseases.Benzene is an important chemical raw material,which is widely used in many fields of industrial production.The International Agency for Research on Cancer(IARC)has listed benzene as one of carcinogens,but its specific mechanism of carcinogenesis remains to be further studied.It has been shown that the toxicity of benzene is mainly mediated by its active metabolites such as hydroquinone(HQ).In recent years,the toxicity of benzene has been studied in depth.For example,benzene can induce the change of miRNAs expression profile of C57BL/6 mouse hematopoietic progenitor cells;In a variety of clinical leukemia samples,the high expression of oncogene miR-221 is related to the poor prognosis of patients.Our previous study found that compared with the control group,the peripheral blood lymphocytes of benzene exposed population contained higher expression of miRNA-221,but the mechanism of which was not clear.In the study of the health effects of environmental pollutants,the research on the role of exosomal miRNAs has just started.Especially the role and mechanism of exosomal miRNAs in the occurrence,development and diffusion of malignant tumors caused by environmental carcinogens is a new field.In this study,we investigated the possibility of exosomal miRNA-221 secreted by malignant cells transmitting cell proliferation signals to recipient cells.The aim of this study is to explore the epigenetic regulation and molecular mechanism of exosomal miRNA-221 in the occurrence,development and diffusion of benzene-induced diseases.ObjectiveThis study is aimed to elucidate the role and mechanism of exosomal miR-221 secreted from hydroquinone-transformed human bronchial epithelial cells in signaling of cells proliferation.Methods16HBE cells treated with 25 ?M hydroquinone had been cultured for 35 generations,thus HQ-transformed malignant cell model(16HBE-T)was established.The CCK-8 analysis and soft agarose colony formation assay were used to assess the malignant degree of 16HBE-T.Exosomes were extracted by ultracentrifugation and were analyzed by transmission electron microscopy.CCK-8 assay was used to investigate the proliferation ability of them.QRT-PCR assay was used to analyze the expression level of miRNA-221 in cells and exosomes.Cells with different expression level of miRNA-221 were established with miRNA-221 mimic or miRNA-221 inhibitor.The exosomes of them were separately extracted and co-cultured with normal 16HBE cells.Their effects on miRNA-221 expression level and proliferation of normal recipient cells were analyzed.Results1.The expression level of miRNA-221 in 16HBE-T cells increased.2.The expression level of exosomal miRNA-221 derived from 16HBE-T cells increased.3.Exosomes enhanced the level of miR-221 of recipient cells.4.The cell proliferation of recipient cells increased when co-cultured with exosomes derived from 16HBE-T.Conclusion1.miR-221 expression was significantly up-regulated in 16HBE-T cells as compared with control.2.Exosomal miR-221 derived from 16HBE-T was significantly up-regulated as compared with control.3.Exosomal miR-221 derived from 16HBE-T elevated the miRNA-221 expression level of recipient cells.4.Exosomal miR-221 derived from 16HBE-T promoted the proliferation of recipient cells.