Knockdown Of PPP2CA Promotes The Malignant Phenotype Of Gastric Cancer Cells Through ATM/METTL3 Axis

Objective: To explore the relationship between PPP2 CA and m6 A methyltransferase complex related proteins in gastric cancer.Methods: 1.The expression of PPP2 CA and m6 A methyltransferase complex related genes in gastric cancer tissues was analyzed by TCGA database.2.Check the phosphorylation sites of METTL3 and WTAP amino acid sequences via Phospho Site website.3.The levels of PP2ACα and METTL3 in gastric cancer tissues and adjacent normal gastric mucosa tissues were detected by immunohistochemistry.4.The PPP2 CA knockdown gastric cancer cell lines BGC-823 and MGC-803 were constructed by sh RNA virus.5.The proliferation ability of gastric cancer cells was detected by clonal formation assay,CCK-8 assay and EDU cell proliferation detection kit.6.The migration and invasion ability of gastric cancer cells were detected by scratch test and Transwell test.7.The expression levels of related genes were detected by RT-q PCR assay.8.Western Blot assay was used to detect the expression levels of related proteins.9.The proliferation level of PPP2 CA knockdown gastric cancer cells in vivo was detected by tumor formation assay in nude mice.10.The inhibition of ATM kinase activity by KU55933 was used to conduct the rescue experiment.Results: 1.Through analysis of STAD project in TCGA database,the results showed that the expression of PPP2 CA was significantly decreased in gastric cancer tissues,and the expression levels of METTL3 and WTAP were significantly increased in gastric cancer tissues,while the expression of METTL14 was not significantly changed.2.Phospho Site website shows a large number of phosphorylation sites on METTL3 and WTAP amino acids.3.Phenotypic experiments in vitro and in vivo showed that inhibition of PPP2 CA expression promoted the proliferation,migration and invasion of gastric cancer cells.4.And during this process,the protein levels of WTAP and METTL3 were significantly increased,and the expression of BATF2 and HDGF(downstream of METTL3,which expressions are related to METTL3 methylation function)were changed accordingly.5.The inhibition of ATM activity by KU55933 could reverse the malignant phenotype of gastric cancer cells caused by knocking out PPP2 CA.Conclusions: Knockdown of PPP2 CA promotes the methylation function and protein levels of METTL3 by increasing ATM kinase activity,and ultimately enhances the malignant phenotype of gastric cancer cells.