Regulatory Mechanism Of Tumor Cell Autophagy By MIR-153 And MIR-520B

Autophagy, also called type-? programmed cell death, is one of the normal life activities of cells. In normal state, cells often maintain a low level of autophagy as a protective mechanism for the survival and growth, but, when the cells are subjected by certain stimulus inside or outside, abnormal autophagy would happen. As a non-coding RNA, microRNA can inhibit target gene mRNA level and translation. However, there are still a large number of autophagy related microRNAs to be excavated. In this study, we found two kinds of microRNAs which can regulate their target gene expression specifically, thus affecting the level of autophagy, and then affecting the cell biological phenotypes, including cell proliferation, migration, invasion, etc..For the preliminary work, we firstly selected two ideal cell models by screening and verification methods. After determining the tumor cell lines, we explorated the optimum induced condition of autophagy in the two cell models. All unpublished microRNAs will be screened. At last, we preliminary screened the research objectives, the next task is to focus on screening results for all aspects of multiple level verification. In addition, we also predicted the target gene of microRNAs by bioinformatics method, and the prediction results were validated by real-time quantitative PCR and Western blot, which can consummate the regulation mechanism.Our Study found, miR-153 and miR-520b could significantly enhance autophagy level of esophageal cancer KYSE450 cells and breast cancer MCF-7 cells, in which miR-520b can combine oncogene CDCA7 and make it silent. At the same time, bioinformatics indicated that CDCA7 and CASP2 are ceRNA to each other, and CASP2 is a autophagy related gene, so CASP2 can regulate the expression of CDCA7 by competing with miR-520b. In the literatures, the consumption of CASP2 gene,which is related to autophagy, can cause the increase of autophagy, so the high expression of miR-520b can promote autophagy. At the same time, the vitro functional experiment showed that miR-153 and miR-520b could significantly inhibit the proliferation, migration and invasion of tumor cells. All in all, these results indicate that miR-153 and miR-520b are potential target molecules for tumor biological therapy.