| BackgroundBreast cancer is a heterogeneous disease initiated by multiple factors.It is the most common type of women cancer and has a higher fatality rate.Many circ RNAs have been proven to promote or suppress cancer in breast cancer.However,the role of circ RPPH1 in breast cancer has not been specifically studied.This article will discuss its role in breast cancer from several aspects: the expression level of circ RPPH1 in breast cancer,the effect of cell function in vitro and in vivo,and the potential mechanism of its role.MethodsAccording to the data set in the GEO database,the abnormally expressed circ RNAs were screened out,and the circ RPPH1 among them was further studied.A total of 40 breast cancer patients were included in this study,and their tumor tissues,adjacent normal tissues and clinical data were collected.First,RT-q PCR was used to detect the expression of circ RPPH1 in breast cancer tissues and paired paracancerous tissues.The relationships between circ RPPH1 and clinical parameters in breast cancer patients were assessed by the chi-square test.In addition,the biological function of circ RPPH1 in breast cancer cell lines was investigated by RNAi and lentiviral.Transwell assay combined with scratch assay was carried out to evaluate the migratory ability of breast cancer cells in vitro.MTT assay and proliferation factor PCNA were used to monitor the proliferation ability of breast cancer cell lines.Colony formation ability was assessed by plate cloning assay.Xenografts experiment and immunohistochemistry confirmed the role of circ RPPH1 in vivo.In order to clarify the possible molecular mechanism by which circ RPPH1 affected the proliferation,colony formation and migration of breast cancer cells,this study first used the database to search for its potential target mi RNAs,and found that mi R-512-5p had potential binding sites with circ RPPH1.Next,the interaction between circ RPPH1 and mi R-512-5p was verified by dual-luciferase reporter assay and RIP assay.The effect of mi R-512-5p on the cell line biological function was evaluated by transwell assay,scratch assay,MTT assay and proliferation factor PCNA.Next,the target genes of mi R-512-5p were predicted through the Target Scan database,and STAT1 was found to be one of its downstream target genes.Then,the relationship between the two was verified by the dual-luciferase reporter assay.Cell experiments were then used to explore the biological role of STAT1 in breast cancer cell lines.Finally,rescue experiments were performed to confirm the role of the circ RPPH1-mi R-512-5p-STAT1 axis in breast cancer.ResultsCirc RPPH1 showed elevated expression levels in the breast cancer group,while mi R-512-5p was lower in the breast cancer group.The expression patterns in the cell lines were also consistent with this.Circ RPPH1 and STAT1 promoted the migration,proliferation and colony formation of breast cancer cells,while mi R-512-5p inhibited these functions.Circ RPPH1 also promoted tumor growth in nude mice.Mechanism studies showed that mi R-512-5p was the downstream mi RNA of circ RPPH1,and STAT1 was the target gene of mi R-512-5p.Circ RPPH1 in the cytoplasm isolated mi R-512-5p from the 3’-UTR of STAT1 through sponge adsorption,making STAT1 more stable in breast cancer.Compared with si-circ RPPH1 transfection alone,co-transfection of si-circ RPPH1 and mi R-512-5p inhibitors could partially eliminate the proliferation inhibition and colony formation inhibition of breast cancer cells caused by si-circ RPPH1.ConclusionCirc RPPH1 showed elevated expression levels both in breast cancer tissues and cells.It showed cancer-promoting effects both in vitro and in vivo.The possible mechanism was that circ RPPH1 in the cytoplasm isolated mi R-512-5p from the3’-UTR of STAT1 through sponge adsorption,making STAT1 more stable in breast cancer.The tumor-promoting effect of circ RPPH1 in breast cancer was achieved by circ RPPH1-mi R-512-5p-STAT1 axis.This provided new targets and basic mechanism information for breast cancer treatment.Our findings promoted the understanding of the occurrence and development of breast cancer,and provided new ideas for the discovery of new therapeutic targets for breast cancer. |
