The Regulation Of Lanthanum Compound On Apoptosis-associated MicroRNAs In Cervical Cancer

Objective：The study was designed to explore the underlying mechanism of lanthanuminhibits the proliferation and induces apoptosis of cervical cancer by analyzing theregulation of lanthanum compound on apoptosis-associated microRNAs, providing anew target for the treatment of cervical cancer.Methods：1. To study the regulation of lanthanum chloride on apoptosis-associatedmicroRNAs in cervical cancer tissues in vivo:Cervical cancer xenograft mouse model was established, and the tumor-bearingmice were divided into control (NS) group and experimental group(Lacl32mg/kg)randomly. The xenograft tissues and normal muscle tissues were collectedrespectively for real-time PCR to detect the relative expression of apoptosis-associated miRNAs, let-7a and miR-34a.2. To study the regulation of lanthanum chloride on apoptosis-associatedmicroRNAs in cervical cancer cells in vitro:(1) Cell culture and sample treatment: the HeLa cells were maintained in RMPI1640medium supplemented with10%heat-inactivated FBS and incubated at37℃ina humidified5%CO2atmosphere. The cells in log growth phase were dividedrandomly into control and experimental groups: in experimental groups, respectively,the cells were treated with lanthanum chloride at different concentrations (5,50and100μM); in control group, cells cultured in normal condition without lanthanumchloride. Then the samples cells were collected for different assays at various timepoints accordingly.(2) Content and medthods:①The growth inhibition oflanthanum chloride on HeLa cells: the cellproliferation inhibition was detected by MTT assay; the cell cycle was analyzed byflow cytometry.②The effects of lanthanum chloride onapoptosis-associated microRNAs in HeLa cells: the relative expression of miRNA let-7a and miR-34a were detected byreal-time PCR.③Theexpression of downstream genes of apoptosis-associated miRNA let-7aand miR-34a: Caspase-3activity was determined by the Caspase-3ColorimetricAssay Kit; CyclinD1and Bcl-2protein expression were detected by Western blot.Results：1. Lanthanum chloride could up-regulate the expression of let-7a and miR-34a incervical cancer tissues in vivo: the relative expression of apoptosis-associatedmiRNAs, let-7a and miR-34a, were up-regulated significantly by lanthanum chloride(2mg/kg) in the experimental group when compared to NS group, P<0.01. And theexpression of let-7a and miR-34a in the NS group were significantly lower than thosein the normal group (P<0.05).2. The regulation of lanthanum chloride on apoptosis-associated microRNAs incervical cancer cells in vitro:(1) Lanthanum chloride inhibited the proliferation of the Hela cells: the tumorgrowth inhibition rates in lanthanum chloride groups (5,50,100μM) were24%,51%and78%, respectively, which were significantly higher than that of the control group(0, P<0.05). And the inhibitory effect was in a dose-dependent manner.(2) Treatment with lanthanum chloride on Hela cells resulted in cell cycle arrestin G1phase in a dose-dependent manner: Compared with the control group, thenumber of G1phase cells increased significantly with the increase of the lanthanumchloride concentrations (5,50,100μM)(P<0.05); meanwhile the number in the Sphase (P<0.05, P<0.01); and G2phase cells decreased remarkably (P<0.05).(3) Lanthanum chloride up-regulated the expression of apoptosis-associatedmiRNAs, let-7a and miR-34a, in HeLa cells: let-7a level was significantly increasedin experimental groups with the treatment of lanthanum chloride in100μM,compared with that of the control group (P<0.01); but little change was found inlower concentration groups (5and50μM)(P>0.05). The level of miR-34a in50μMand100μM lanthanum chloride groups were all increased significantly (P<0.01), butin5μM lanthanum chloride group, the level almost stayed the same.(4) The expression of downstream genes of apoptosis-associated miRNA let-7a and miR-34a: lanthanum chloride could induce the expression of activated Caspase-3dose-dependently; the expression of CyclinDl and Bcl-2were decreased remarkablyby the treatment of lanthanum chloride in a dose-dependent manner.Conclusion：Lanthanum chloride inhibited proliferation and induced apoptosis of cervicalcancer by up-regulating the expression of apoptosis-associated miRNAs let-7a andmiR-34a, which paralleled by corresponding changes in the proteins and the cellcycle arrest, as well as apoptosis in cervical cancer.