The effect of Phosphoinositide-3-kinase, regulatory subunit 3 in epithelial-mesenchymal transition and migration of non-small cell lung cancer

Abstract

Objective To test the expression of phosphoinositide- 3- kinase, regulatory subunit 3 (PIK3R3)in the human non- small cell lung cancer(NSCLC) tissues, and to observe the effect of PIK3R3 on the epithelial- mesenchymal transition(EMT)and migration of NSCLC cell lines A549 and PC- 9. Methods Total RNA and total protein lysate from the NSCLC tissues and paratumor tissues of 22 or 7 patients with NSCLC were prepared respectively,and the expression of PIK3R3 was tested by real- time quantitative polymerase chain reaction(Real- time PCR)and Western blotting;PIK3R3 was overexpressed or down- regulated by lentivirus infection, then the effect of PIK3R3 on the migration was detected by Transwell assay, and the expression of EMT related proteins were detected by Western blotting,and the binding of snail family zinc finger(SNAI)1 and SNAI2 on the promoter of cadherin 1(CDH1)were measured by chromatin immunoprecipitation assay(ChIP),and the transcription activity of CDH1 was detected by luciferase reporter assay. Results The expression of PIK3R3 was elevated in NSCLC patients'tumor tissues compared with the paratumor tissues; The migration of A549 and PC- 9 cells was enhanced after PIK3R3 overexpression(A549 Control:46±3, PIK3R3:92±5; PC- 9 Control:25±2, PIK3R3:53±3), with the expression of CDH1 depressed and elevation of VIM, SNAI1 and SNAI2, which were related to the progress of EMT; The binding activity of SNAI1 and SNAI2 on the CDH1 promoter was elevated 9 times and 3.8 times, respectively, and the transcriptive activity of CDH1 was depressed to 30%.To the opposite, the migration of A549 and PC- 9 cells were inhibited after PIK3R3 down- regulated(A549 sh- Control:58±5,sh- PIK3R3:13±3; PC- 9 sh- Control:28±5,sh- PIK3R3:10±3), with the expression of CDH1 elevation and depressed of VIM, SNAI1 and SNAI2.The binding activity of SNAI1 and SNAI2 on the CDH1 promoter was reduced, and the transcriptive activity of CDH1 was increased 3.6 times. Conclusion The expression of PIK3R3 was elevated in NSCLC,and overexpression of PIK3R3 could induce the EMT and migration of A549 and PC- 9 cells;on the contrary, down- regulation of PIK3R3 could inhibit the EMT and migration of A549 and PC- 9 cells. Key words: Phosphoinositide-3-kinase; Regulatory subunit 3; Non-small cell lung cancer; Migration; Epithelial-mesenchymal transition