Studies Of USP18 On Proliferation Of Breast Cancer

Cell is an organic system and various proteins play important roles in the development of cell life.Therefore,the synthesis and degradation of proteins by a variety of systems are strictly regulated.Thirty percent of the new proteins are rapidly degraded with a half-life less than 10 minutes.In this rapid degradation process,efficient protein systems are required to play a corresponding role,so that the ubiquitin proteasome system exists.The ubiquitin proteasome system,an important pathway for protein degradation,can degrade unwanted proteins in 80% of cells.Its functions include degradation of misfolded and damaged proteins,cell cycle regulators,oncogenes and tumor suppressors,regulation of antigen presentation and transcription factors activity.In recent years,UPS systems have received widespread attention as targets for oncology treatments.USP18 is a member of UPS,belongs to the DUBs family.For the moment,USP18 mainly includes the following functions: 1 USP18 plays a role in the development of CD1 b + DCs and TH17 cells.Defective USP18 impaired BMDCs cell development in mice,and USP18 plays an important role in differentiation of TH17 cells and in innate immunity.2 As a member of UPS,USP18 exerts de-ubiquitination function to hydrolyze ISG15 from substrate and inhibit the type I interferon pathway.3 USP18 inhibits the type I interferon pathway to enhance viral replication in order to facilitate the initiation of adaptive immunity.4 In MCF-7 and leukocytes,defective cells proliferation and apoptosis are arrested,either by inhibiting the type I interferon pathway or accelerated cell proliferation.In this multi-way relationship,we discussed the role of USP18 in some breast cancer cells.In our previous work,we used the CRISPR/Cas9(Clustered regular interspaced short palindromic repeats/CRISPR-associated protein 9)system to screen genes associated with cell proliferation in MDAMB231 breast cancer cells.Screening found that USP18 had an effect on the proliferation of MDAMB231 cells.To further understand its role,we first performed excavation in a database.Vertical analysis revealed that USP18 m RNA is excessive relative to normal tissue in a variety of tumor cells.In the lateral analysis,patients with higher levels of USP18 expression in breast cancer patients generally had poor overall survival,disease-free survival,and no distant metastatic survival.Therefore,we believe that the expression of USP18 has a great relationship with breast cancer.Then we used sh RNA(short hair-pin RNA)and CRISPR/Cas9 technology to knock down USP18 in breast cancer cells.We observed that the proliferation of tumor cells in the knockdown group was slowed down through clone formation assay and cell MTS assay results.Overexpression of USP18 cells proliferation was accelerated,and the overexpression of reverted cells demonstrated that the reason for the proliferation of tumor cells was USP18.At the same time,we studied the localization of USP18 in cells and found that it is mainly located in the cytoplasm.Next,we found through periodic experiments that USP18 can significantly affect the cycle of tumor cells and lead to apoptosis and senescence.We found that knockdown of USP18 inhibited breast cancer cell proliferation,induced apoptosis,and senescence.