| With the deepening of the human genome research project,many miRNAs had been found in disorder at the early diagnosis and pathogenesis of human malignancies,and this also included the high prevalence of breast cancer in the world.In the meantime,many previous studies had shown that miRNAs could regulate tumor suppressor genes or oncogenes.Some miRNAs were emerging as biomarkers for colorectal cancer and had been used in prognosis,diagnosis and even prediction the outcome of treatment.miRNAs had shown great potential in regulating the function of colorectal cancer cells,such as proliferation,invasion,apoptosis,metastasis and drug resistance.In addition,miRNAs circulating in the body fluids of cancer patients could be used as a noninvasive detection tool for patients with breast cancer to readily observe the patient's personal health status.Therefore,in-depth study of miRNAs in breast cancer tissue regulation has important clinical significance.Research purposesMicroRNAs(miRNAs)were identified as important biomarkers in the diagnosis and treatment of breast cancer.We determined expression of mi RNAs in patients with lung cancer by RNA-seq and identified mi R-22-5p to be significantly down-regulated in lung cancer tissue.Further assays by RT-PCR presented that increased expression of ATP citrate lyase(ACLY)induced decreased level of miR-22-5p indicating ACLY might inhibit miR-150 in expression.This study aimed to further explore the potential regulatory mechanisms of miR-22-5p in the regulation of cell proliferation,invasion,apoptosis and metastasis in breast cancer.Research methods(1)By using the second generation sequencing technology to screen the significant difference genes in breast cancer tissues and peripheral non-tumor tissues,the sequencing data analysis was performed to screen the genes that expressed significant differences,and to analyze the miRNAs related to breast cancer-related differences.RT-qPCR was used to verify the difference expression levels of miR-22-5p in breast cancer tissues and peripheral non-tumor tissues.(2)The overall survival and clinicopathological features of breast cancer patients were analyzed by the retrospective study to miR-22-5p expression level,and clarified the clinical significances of miR-22-5p expression levels in breast cancer.(3)Through the use of CCK-8,flow cytometry,immunofluorescence detection,invasion and migration experiments and other in vitro functional detection technology,the analysis of miR-22-5p expression levels on proliferation,apoptosis,migration,invasion and tumor function of MCF-7 cells were detected.(4)Through gene microarray analysis of MCF-7 cells knocked down/overexpressed miR-22-5p,aberrantly expressed proteins were screened,and the effects of aberrantly expressed proteins and miR-22-5p on the function of tumor cells were further investigated by immunofluorescence and immunoblotting.(5)By constructing tumor xenograft model in mice,the up-regulated and down-regulated expression of miR-22-5p was studied on the biological function of breast cancer solid tumors.Research results(1)We found that the expression of miR-22-5p in breast cancer tissues and peripheral non-tumor tissues was different through second-generation sequencing,and it was confirmed that the expression of miR-22-5p was significantly reduced in breast cancer tissues.(2)Retrospective analysis showed that the low expression of miR-22-5p was positively correlated with the high incidence and poor prognosis of advanced disease TNM grade,lymphoid tissue metastasis,and tumor cell metastasis of breast cancer.(3)The up-regulated expression of miR-22-5p could inhibit the proliferation,migration and invasion of MCF-7 cells in colon cancer,and also induce apoptosis of tumor cells,while the down-regulated expression results were reversed.(4)The gene microarray was used to screen out the abnormally expressed protein ACLY.The miR-22-5p expression regulation experiments showed that the overexpression of miR-22-5p gene could reduce the expression of ACLY protein,and the down-regulated expression of miR-22-5p had the opposite results.And their increased expressions in the cytoplasm lead to accelerate the degradation of cancer cells.(5)When miR-22-5p is up-regulated,it can inhibit the growth of ACLY overexpressing tumor cells and promote its apoptosis.In addition,the regulation of miR-22-5p on tumor growth was also confirmed in animal models.ConclusionThe present study showed that miR-22-5p was down-regulated in breast cancer tissues and affects the metastasis and prognosis of breast cancer.Up-regulation of miR-22-5p could regulate the biological function of tumors by down-regulating the expression of ACLY protein,which could be used as a tumor suppressor.It was indicating that miR-22-5p/ACLY could be used as a new prognostic biomarker and therapeutic target of breast cancer,and had important clinical therapeutic and research significance. |
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