The Effects Of RhoGDIa On Apoptosis Of Lung Cancer Cells And It's Signaling Proteins

Objective :To investigate the effects of RhoGDIαon apoptosis of lung cancer cells and on the signaling proteins invovled in apoptosis.Methods :1. RhoGDIαsiRNA was used to target and knock down RhoGDIαin A549 cell. FCM was used to detect cell apoptosis. The expression levels of RhoGDIαand signaling proteins such as P-IκBα, P-AKT , P-ERK , P-JNK and P-BAD were analysed by Western blot.2. The chemosensitivity to paclitaxel of A549 cell transfected with RhoGDIαsiRNA were studied, and the expression levels of RhoGDIαand the related signaling proteins of apoptosis were analysed.3. To conform the results aquired in A549 cell research, the expression levels of RhoGDIαand the related signaling proteins in forty tissue specimens of patients with lung cancer were determinded by immunohistochemical technique. The correlations between the expression level of RhoGDIαand the signaling proteins were analysed.Results :1. After knockdown RhoGDIα, the apoptosis level of A549 cell increased four times(18.28%±3.16% vs 4.40%±0.8% , P<0.05) with significant upregulation of P-JNK(P<0.05) and significant downregulation of P-BAD,P-IκBαand P-ERK(P<0.05 , 0.05 and 0.05, respectively). 2. Paclitaxel induced apoptosis and G2/M arrest in A549 cell. A low concentration of paclitaxel (10nM) led to a two-fold increase in apoptosis level in A549 cells( 3.22%±0.16% vs 1.52%±0.14%,P<0.05), and the increased level of apoptosis accompanied significant upregulation of P-IκBαand P-ERK(P<0.05 and 0.05 , respectively).3. A low concentration of paclitaxel (10nM) led to a eight-fold increase in apoptosis level in A549 cells transfected with RhoGDIαsiRNA (12.49%±1.03% vs 1.52%±0.14%,P<0.05), which accompanied significant upregulation of P-JNK(P<0.05) and significant downregulation of P-BAD, P-IκBαand P-ERK(P<0.05, 0.05 and 0.05 , respectively).4. The expression level of RhoGDIαin lung cancer tissues was significantly higher than in para-cancerous tissues(85% vs 60%,P=0.0267). In lung cancer tissues, the expression level of RhoGDIαprotein was positively correlated with that of P-BAD protein (r=0.459,P=0.0029) ,and negatively correlated with that of P-JNK(r=-0.336,P=0.034), and the expression levels of P-JNK and P-IκBαprotein were negatively correlated(r=-0.321,P=0.043).Conclusions:1. RhoGDIαmay play a important role in apoptosis in lung cancer, and knockdown RhoGDIαcan induce apoptosis in A549 cell.2. Downregulation of RhoGDIαmay enhance apoptosis in A549 cell through the activiation of JNK pathway and the inhibition of BAD,NFκB and ERK pathway.3. A low concentration of paclitaxel (10nM) may induce apoptosis and G2/M arrest in A549 cell accompanied the activiation of ERK and NFκB pathway.4. Downregulation of RhoGDIαincreased the chemosensitivity to palitaxel in A549 cell through the activiation of JNK pathway and the inhibition of BAD, NFκB and ERK pathway.5. In lung cancer tissues, the expression level of RhoGDIαsignificantly elevated and was positively correlated with that of P-BAD and negatively correlated with that of P-JNK.6. The collective results in vitro and in cancer tissue suggested that the inhibitory effect of RhoGDIαon apoptosis through JNK, BAD, NFκB and ERK pathway may promote lung cancer formation and development.