OBJECTIVE To investigate the regulatory effect of Rasfonin on SOS1(Son of Seven-less,one of the major guanylate exchange factors)expressions and the underlying mechanism.METHODS① Human cancer cells MCF-7(breast cancer cells,KRASWT wild-type),Calu-1(non-small cell lung cancer,KRASG12C mutation),and UM-UC-3(bladder metastatic cell carcinoma,KRASG12C mutation)were divided into the control group and Rasfonin(1,5,10 and 15 μmol·L-1)treated groups.CCK-8 assay was used to observe the effects of Rasfonin on the proliferation of MCF-7,Calu-1,and UM-UC-3 cells after 24 h of Rasfonin treatment.In addition,these cells were divided into the control group,EGF stimulation group(EGF 50 μg·L-1,stimulated for 5 min),and Rasfonin treated groups(pretreated with 5 and 10 μmol·L-1 Rasfonin before 5 min EGF stimulation).Quantitative real-time PCR(real-time fluores-cence PCR)and Western blotting were employed to identify the expression levels of SOS1 mRNA and protein in MCF-7,Calu-1 and UM-UC-3 cells.② The co-expression systems of KRAS and SOS1 were established by transfecting plasmids(KRAS-NC,KRASWT,KRASG12C and SOS1)into 293T cells that were divided into the control group and Rasfonin(1,5 and 10 μmol·L-1)treated group.The dual luciferase reporter gene assay was used to evaluate the effects of Rasfonin on activities of the SOS1 promoter.Moreover,293T cells were divided into the EGF stimulation group(EGF 50 μg·L-1,stimulated for 5 min)and Rasfonin treated groups(12 h of treatment with 10 μmol·L-1 Rasfonin before 5 min EGF stimula-tion).Western blotting was performed to determine the role of KRASG12C protein in the inhibition of Rasfonin on SOS1 expression.RESULTS ① Compared with the control group,Rasfonin inhibited the prolifera-tion of Calu-1 and UM-UC-3 cells at concentrations of 5,10 and 15 μmol·L-1(IC50 was 8.22 and 4.94 μmol·L-1).But for MCF-7 cells,only 15 μmol·L-1 Rasfonin could decrease their viability(IC50 was 45.15 μmol·L-1).Compared with the EGF stimulation group,mRNA expressions of SOS1 were increased after Rasfonin treatment of 1 h.mRNA expressions of SOS1 were decreased in Calu-1 cells after 3 h of Rasfonin treatment.These changes also occurred after Rasfonin treatment of 3 h and 6 h in UM-UC-3 cells.Further-more,Rasfonin treatment did not influence SOS1 protein expressions in MCF-7 cells,but can signifi-cantly inhibit SOS1 expression of in UM-UC-3 and Calu-1 cells.② Rasfonin had no significant effects on the activity of SOS1 promoter and its protein level in 293T cells when only SOS1 was expressed,but significantly inhibited its activity and its protein level when SOS1 was co-expressed with KRAS protein.CONCLUSION One of the anti-tumor mechanisms of Rasfonin is to inhibit the activity of SOS1 promoter to decrease mRNA and protein expressions of SOS1 through KRASG12C protein.

OBJECTIVE To investigate the regulatory effect of Rasfonin on SOS1(Son of Seven-less,one of the major guanylate exchange factors)expressions and the underlying mechanism.METHODS① Human cancer cells MCF-7(breast cancer cells,KRASWT wild-type),Calu-1(non-small cell lung cancer,KRASG12C mutation),and UM-UC-3(bladder metastatic cell carcinoma,KRASG12C mutation)were divided into the control group and Rasfonin(1,5,10 and 15 μmol·L-1)treated groups.CCK-8 assay was used to observe the effects of Rasfonin on the proliferation of MCF-7,Calu-1,and UM-UC-3 cells after 24 h of Rasfonin treatment.In addition,these cells were divided into the control group,EGF stimulation group(EGF 50 μg·L-1,stimulated for 5 min),and Rasfonin treated groups(pretreated with 5 and 10 μmol·L-1 Rasfonin before 5 min EGF stimulation).Quantitative real-time PCR(real-time fluores-cence PCR)and Western blotting were employed to identify the expression levels of SOS1 mRNA and protein in MCF-7,Calu-1 and UM-UC-3 cells.② The co-expression systems of KRAS and SOS1 were established by transfecting plasmids(KRAS-NC,KRASWT,KRASG12C and SOS1)into 293T cells that were divided into the control group and Rasfonin(1,5 and 10 μmol·L-1)treated group.The dual luciferase reporter gene assay was used to evaluate the effects of Rasfonin on activities of the SOS1 promoter.Moreover,293T cells were divided into the EGF stimulation group(EGF 50 μg·L-1,stimulated for 5 min)and Rasfonin treated groups(12 h of treatment with 10 μmol·L-1 Rasfonin before 5 min EGF stimula-tion).Western blotting was performed to determine the role of KRASG12C protein in the inhibition of Rasfonin on SOS1 expression.RESULTS ① Compared with the control group,Rasfonin inhibited the prolifera-tion of Calu-1 and UM-UC-3 cells at concentrations of 5,10 and 15 μmol·L-1(IC50 was 8.22 and 4.94 μmol·L-1).But for MCF-7 cells,only 15 μmol·L-1 Rasfonin could decrease their viability(IC50 was 45.15 μmol·L-1).Compared with the EGF stimulation group,mRNA expressions of SOS1 were increased after Rasfonin treatment of 1 h.mRNA expressions of SOS1 were decreased in Calu-1 cells after 3 h of Rasfonin treatment.These changes also occurred after Rasfonin treatment of 3 h and 6 h in UM-UC-3 cells.Further-more,Rasfonin treatment did not influence SOS1 protein expressions in MCF-7 cells,but can signifi-cantly inhibit SOS1 expression of in UM-UC-3 and Calu-1 cells.② Rasfonin had no significant effects on the activity of SOS1 promoter and its protein level in 293T cells when only SOS1 was expressed,but significantly inhibited its activity and its protein level when SOS1 was co-expressed with KRAS protein.CONCLUSION One of the anti-tumor mechanisms of Rasfonin is to inhibit the activity of SOS1 promoter to decrease mRNA and protein expressions of SOS1 through KRASG12C protein.

Objective To investigate the effects of metoprolol succinate sustained-release tablets on acute phase ventricular pacing threshold and intracardiac electrical signal amplitude in a leadless pacemaker(Micra).Methods A total of 100 patients implanted with a leadless pacemaker were selected and divided into a study group(n=43)and a control group(n=57)according to whether oral metoprolol succinate sustained release tablets were postoperatively administered.The patients with underlying diseases including hypertension,coronary heart disease,or diabetes were treated with antihypertensive drugs,hypoglycemic drugs,or anti-platelet aggregation drugs.The study group received oral metoprolol succinate sustained release tablets within one to three days after implantation of a leadless pacemaker;while the control group received no metoprolol succinate sustained release tablets.Changes in ventricular pacing threshold and intracardiac electrical signal amplitude were observed in two groups one week,one month and three months after implantation.Results No serious complications occurred in the patients at the three time points after implantation.Ventricular pacing thresholds were stable in both groups,and there was no statistical significance between the two groups as compared with the same time period(P>0.05).In terms of amplitude of ventricular intracardiac electrical signal,theamplitude of ventricular R-wave did not differ significantly between the two groups at the three time points after implantation(P>0.05).Conclusions Oral administration of metoprolol succinate sustained release tablets had no significant effects on acute phase ventricular pacing threshold and intracardiac electrical signal amplitude in a leadless pacemaker(Micra).

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