The Role Of Lanthanum Chloride On Cancerous Cell Growth And Invasiveness

ObjectiveThe formation of distant metastasis is the main cause of morbidity and mortality in patients with cancer.Invasion is a fundamental characteristic of malignant tumor and the first step in the metastatic process.The molecular mechanisms involved in tumour cell invasion are complex,but many proteins with important roles in invasion have been identified and characterized,such as MMP-2 and c-met.In addition,one of the new aspects for cancer therapy is to appraise natural reagents' efficacy in the treatment.Our goal is to investigate the effects of lanthanum chloride on tumour cell invasion and metastasis.Two targets involved these processes are discussed to make clear the mechanism of lanthanum chloride on cancer therapy and provide further evidence to push rare earth in practice.MethodsA.The role of lanthanum chloride on the proliferation of MCF-7 and HT-1080 cell lines was measured by MTT assay.B.Modified Boyden chamber assay was applied to look at the further effects of lanthanum chloride on the invasion of HT-1080 cell line.C.To observe the change of MMP-2 secretion and activity,the conditional culture media were tested by Zymography and Western Blot,respectively.D.The transcriptions of different target proteins were observed through RT-PCR. That is the MMP mRNA of HT-1080 and c-Met mRNA of MCF-7.E.Luciferase reporter plasmid and plasmids contained different MMP-2 promoter mutations were constructed for measuring the activity of MMP-2 promoter.The involved signal pathway on the regulation of MMP-2 transcription was explored.ResultsA.When treated with low concentration of lanthanum chloride(＜50μmol/L),the growth of MCF-7 and HT-1080 cell lines was not influenced.As the concentration of lanthanum chloride increased,the proliferation of cell lines were inhibited with does dependent.However,if the concentration of lanthanum chloride was too high(＞400μmol/L),it may lead to large amount of cell death or apotosis and the does dependent response of drug disappeared.Moreover, different cell lines responded difference to lanthanum chloride.In this study, HT-1080 cell line was more sensitive to lanthanum chloride than MCF-7.B.In HT-1080 cells,lanthanum chloride repressed cell metastasis behavior much more efficiently than cause cytotoxicity through invasion assay.C.When the concentrations of lanthanide chloride were 10,15 and 20μM,the secretion of the MMP-2 was almost completely inhibited.Meanwhile,no noticeable change between the secretions of mature MMP-2 at different lanthanum chloride concentrations.The gelatinase activity of pro-MMP-2 substantially diminished,whereas no change was noticed in that of MMP-2.D.We have discovered that lanthanum chloride repressed MMP-2 transcription through RT-PCR results.In the meantime,we found low concentration of lanthanum chloride also down regulated the c-Met mRNA transcription.E.Sequential deletions of MMP-2 promoter revealed a lanthanum-responding region, and mutation of a potential CREB site in this region generated a promoter lacking response to either lanthanum chloride or a cAMP agonist,suggesting lanthanum might intercept PKA/CREB pathway to inhibit MMP-2 gene transcription and lead to the reduction of MMP-2 secretion.ConclusionsThe role of lanthanum chloride on cancerous cell depended on its concentration.High concentration of lanthanum chloride inhibited the proliferation of tumour cell lines, but low concentration of lanthanum chloride has effects on tumour cell invasion.We have found tumour cell invasion suppressed related extracellular proteases and oncogene expression and transcription.Our study provided basic evidence for individual cancer therapy and may lead to the development of novel application of rare earth.