GSK-3β:the Keytarget Of Octreotide Inhibits Wnt/β-Catenin Pathway In SW480Cells

Objective:In this study, we can compare the changes of proliferation and apoptosis ofSW480cells, and the differences of β-Catenin、GSK-3β expression by octreotide inthe Wnt/β-Catenin signaling pathway by lithium chloride (GSK-3β inhibitor)pretreatment, to clarify further the antitumor mechanism and the drug targets ofoctreotide in the pathway.Methods:To cultivate human colon cancer SW480cells in vitro as the experimentalsubject, it was divided into six groups: group A-control group (PBS);group B-Octreotide (OCT10-8mM);group C-Octreotide (OCT10-10mM); group D-lithiumchloride group (LiCl20mM);group E-Octreotide+lithium chloride (OCT10-8mM+LiCl20mM);group F-Octreotide+lithium chloride (OCT10-10mM+LiCl20mM).MTT assay was used to screen intervention concentration of LiCl; MTT assay toanalyse proliferation inhibitory rate of SW480cells;FCM assay to analyse apoptosisrate and cell cycle of SW480cells;Western blot assay to analyse the proteinexpression of non-phosphorylated β-Catenin and GSK-3β,p-GSK-3β(Tyr216),p-GSK-3β(Ser9).Results：1.MTT assay results of screening lithium chloride(LiCl) effective interventionconcentration show that:2000mM and200mM LiCl could inhibit proliferation ofSW480cells(P<0.05);2mM LiCl could promote proliferative at48h (P<0.05),there were no significant biological effects in other time periods (P>0.05);20mMof LiCl showed no significant promotion or inhibition effect of proliferation inthree time periods (P>0.05). Therefore, select20mM LiCl as the experimentaleffective intervention concentration. 2.MTT assay results of proliferation inhibitory rate in experimental groups show that:The proliferation inhibitory rates of SW480cells in group B and C were increased,and statistical analysis indicated that differences were significant(P＜0.05),andlargest in48hour. Relative to group B and C,the proliferation inhibitory rates ingroup E and F were reduced but they had no significant differences(P>0.05).3.FCM assay results: The apoptosis rates of SW480cells in group B and C wereincreased, and statistical analysis indicated that differences were significant(P＜0.05),and cells in G0/G1phase gradually increased. Relative to group B and C, theapoptosis rates in group E and F were reduced but they have no significantdifferences in G0/G1phase cells(P>0.05).4.1. Western blot analysis: The non-phosphorylated β-Catenin protein expression wassignificantly downregulated in group B and C(P＜0.01), and statistical analysisindicated that differences were significant(P＜0.05); Relative to groupB and C,thenon-phosphorylated β-Catenin protein expression were upregulated in group E andF (P<0.05) but not different (P>0.05); It was upregulated in group D(P＜0.05).4.2.Western blot analysis: The non-phosphorylated GSK-3β and p-GSK-3β(Tyr216)protein expression were significantly upregulated in group B and C(P＜0.01), andstatistical analysis indicated that differences were significant(P＜0.05); Relative togroup B and C,non-phosphorylated GSK-3β and p-GSK-3β(Tyr216) proteinexpression were downregulated in group E and F (P＜0.05) but not different (P>0.05); It was downregulated in group D(P＜0.05).4.3Western blot analysis: The p-GSK-3β(Ser9) protein expression was significantlydownregulated in group B and C(P＜0.01), and statistical analysis indicated thatdifferences were significant(P＜0.05); Relative to group B and C,thep-GSK-3β(Ser9) protein expression were upregulated in group E and F (P＜0.05)but not different (P>0.05); It was upregulated in group D(P＜0.05). Conclusion:1.Octreotide could inhibit proliferation and induced apoptosis of colon cancer SW480cells in vitro,blocked cell cycle in G0/G1phase; Inhibition of GSK-3β activity couldweaken antitumor effect.2.Octreotide inhibited the Wnt/β-Catenin pathways, was through activating GSK-3βprotein to prevent signal transmission to achieve.