Preliminary Study On The Effect Of FBW7 New Interaction Protein SRSF9 On The Malignant Phenotype And Metabolism Of Colon Cancer Cells

Colon cancer,as one of the top three cancer types in terms of mortality,has shown a trend of becoming younger in recent years.Although the relevant clinical treatment methods are improving,the survival rate of patients is low due to the absence of symptoms in the early stage of colon cancer,the inability to achieve early detection and treatment and the poor prognosis after the operation.Therefore,elucidating the molecular mechanism of colon cancer development is of great significance to the clinical treatment of colon cancer and the selection of new drug targets.As a tumor suppressor protein,FBW7 regulates the stability and function of various tumor-related proteins through ubiquitination to affect the development of tumors.Downregulation or inactivation of FBW7 is closely related to the occurrence of colon cancer.In this study,we used protein immunoprecipitation and mass spectrometry to find that SRSF9 and FBW7 may have an interaction,and further confirmed their interaction in293 T cells through co-IP experiment.Through gradient overexpression of FBW7 and CHX experiments,we found that the interaction between FBW7 and SRSF9 will affect the stability of SRSF9.SRSF9 has been found to be up-regulated in a variety of tumors,including colon cancer,but there are few reports on the carcinogenic mechanism of SRSF9.In this study,the effect of SRSF9 on the proliferation,migration and apoptosis of colon cancer cell line SW480 was analyzed after the expression of SRSF9 was down-regulated by si RNA,the results showed that down-regulation of SRSF9 can significantly inhibit the proliferation and migration of SW480 cells and significantly promote the apoptosis of this cell line.SRSF9,as a member of the SR protein family,plays an important role in RNA alternative splicing.We used RNA-seq technology to detect the changes of associated variable splicing in SW480 cells before and after SRSF9 knockdown,the results showed that genes with significant splicing changes in m RNA were mainly enriched in signaling pathways such as metabolic pathways,ubiquitin-mediated proteolysis,RNA transport and spliceosomes,the metabolic pathway is the pathway with the most gene enrichment.We selected two downstream target genes SHMT1 and SHMT2 which are regulated by SRSF9 m RNA alternative splicing,these two genes have obvious changes in alternative splicing forms before and after SRSF9 knockdown,and they encode different subtypes of serine hydroxymethyl transferase,catalyzing the conversion of serine / glycine and providing one carbon unit.This is the main source of one carbon unit in metabolism,and cell metabolism is considered to be a sign of tumor.SHMT1 exerts oncogene functions in a variety of tumors and SHMT2 has also been found to be up-regulated in a variety of tumors,both of which are more meaningful targets for research.This study initially found that a potential new pathway such as FBW7 / SRSF9 / SHMTs may exist in colon cancer,which will provide us with a new idea to deeply understand the molecular mechanism of colon cancer and find effective therapeutic targets.