Rab22a Promotes Proliferation、Migration And Invasion By Activating PI3K/AKT/mTOR Signaling Pathway

Objective: RAB22 A is located in the early endosome and participates in a series of endometrial circulation activities,such as vesicle formation.RAB22 A has been proved to be overexpressed in many tumors.In recent years,RAB22 A has made some new progress in tumor research.For example,the overexpression of RAB22 A promotes the proliferation and cycle progression of nasopharyngeal carcinoma cells;the abnormal expression of RAB22 A caused by aberrant chromosome of RAB22 A can drive the metastasis of osteosarcoma.However,the research mechanism of RAB22 A in lung adenocarcinoma remains to be explored.Therefore,we studied the expression of RAB22 A in lung adenocarcinoma,and revealed the potential mechanism of RAB22 A promoting proliferation,invasion and migration of lung adenocarcinoma.Methods: We collected 107 paraffin embedded specimens of NSCLC and 16 pairs of fresh lung adenocarcinoma(LAUD)tissues from ***.Then,we applied immunohistochemistry to analyze the expression of RAB22 A in 64 cases of lung adenocarcinoma and 43 cases of lung squamous cell carcinoma(LSCC),and the relationship between the expression of RAB22 A and clinicopathological factors.Western blot was used to detect the expression of RAB22 A in five lung cancer cell lines and an immortalized bronchial epithelial cell.Western blot was used to detect RAB22 A protein levels in 16 pairs of fresh lung adenocarcinoma tissues and adjacent normal tissues.After that,RAB22 A protein and GTPase activity were regulated by transfection and interference technology in lung adenocarcinoma cell lines.The effects of RAB22 A on proliferation,migration and invasion of lung adenocarcinoma cells were investigated by cell proliferation assay(CKK8),colony formation assay,matrix gel invasion assay and scratch assay The effects of RAB22 A protein level and GTPase activity on PI3 K / AKT / mTOR pathway activity and the protein levels of PI3kp85α,p-AKT,AKT,p-mTOR,mTOR,p-4e-BP1,p-p70s6k(389)and p-p70s6k(371)were detected.In addition,the protein levels of target genes p-mTOR,mTOR and downstream target proteins p-4e-bp1,p-p70s6k(389)and p-p70s6k(371)were detected by Western blot.The binding of RAB22 A to PI3kp85α was detected by immunoprecipitation.Repeat the experiment to confirm the above results.Spss22.0 statistical analysis software and graphpad prism 7.0 were used to analyze the experimental data.P < 0.05 showed that the results were significantly different.Results:1.Immunohistochemical analysis showed that the expression of RAB22 A was different between lung adenocarcinoma and lung squamous cell carcinoma.The expression level of RAB22 A in 64 cases of lung adenocarcinoma was higher than that in normal lung tissue.Meanwhile,the expression of RAB22 A in 16 pairs of fresh lung adenocarcinoma tissues detected by Western blot was significantly higher than that in the paired normal lung adenocarcinoma tissues.2.We found that overexpression of RAB22 A in lung adenocarcinoma cell lines A549 and H1299 could significantly promote the proliferation,migration and invasion of tumor cells,while interference with RAB22 A had the opposite effect.The mutation of GTPase activity had no significant effect on the proliferation,migration and invasion of adenocarcinoma cells.3.Co immunoprecipitation in A549 cells showed that RAB22 A interacted with pi3kp85α to regulate the target genes of PI3 K / AKT / mTOR signaling pathway and increase the protein phosphorylation levels of AKT,mTOR,4E-BP1 and P70S6 K.4.Rapamycin,an mTOR inhibitor,was used in A549 and H1299 lung adenocarcinoma cell lines.Western blotting showed that rapamycin inhibited the phosphorylation of mTOR protein and the phosphorylation of downstream target proteins 4E-BP1 and P70S6 K.5.We found that overexpression of RAB22 A in lung adenocarcinoma cell lines A549 and H1299 significantly promoted the proliferation,invasion and migration of tumor cells,and rapamycin inhibited the proliferation,migration and invasion of lung adenocarcinoma cells.Conclusion:1.The expression of RAB22 A in lung adenocarcinoma was higher than that in adjacent normal tissues.2.RAB22 A protein can promote the proliferation,migration and invasion of lung adenocarcinoma cells,but GTPase activity has no effect on the proliferation,migration and invasion.3.RAB22 A interacts with PI3Kp85α and activates PI3K/AKT/mTOR signaling pathway.4.RAB22 A promoted ADC cell proliferation,migration and invasion by activating PI3 K / AKT / mTOR signaling pathway.