To Explore The Mechanisms Of GPER-induced Tamoxifen Resistance In Breast Cancer By Microarray

Objective To understand the target genes of G-protein coupled receptor(GPR30, GPER) in MCF-7tamoxifen resistance cell line of breast cancerby cDNA microarrays and information biology.And the influence of signalpathway in the cells.To explore the role in the development of tamoxifenresistance of MCF-7cell line for a new therapeutical target point. Thisstudy provides novel insights into the complex events of the adaptivesignaling network induced by GPER occurring during the acquisition of thetamoxifen resistance in breast cancer cells.Methods MCF-7cells were cultured with1μM4-OH Tam (4-OHT) overa period of21days to obtain the resistance cell line (MCF-7R). MTT andFCM (flow cytometry) were used to detect the survival rate and S-phaseratio of MCF-7and MCF-7R cells for identifying the cell resistance totamoxifen. The target genes of GPER expression profiles were analyzedwith Agilent Microarray chip. Real time quantitative PCR and WesternBlots were used to verify random selected target genes.Immumofluorescense was used to present cytoskeleton, the ability of migration of cells were confirmed by transwell assay. Online pathwayanalysis was performed to assess gene signatures related with tamoxifenresistance.Results MCF-7R cell line was obtained successfully. The migrationability of MCF-7R cell line is largely enhanced compared to MCF-7cellline. The cytoskeleton of MCF-7cells obviously changed after acquiringtamoxifen resistance. Gene microarray analysis revealed that1670targetgenes were found significantly up-regulated in MCF-7R cell line and78genes significantly up-regulated compared with MCF-7cell line.Interestingly, the actin cytoskeleton signaling which governs the cellmigration was identified to be a GPER-dependent signaling pathways inMCF-7R cells. Fortunately, one of target gene, β1integrin in the actincytoskeleton signaling was verified to play a critical role in conferringtamoxifen resistance and enhancing cell motility.Conclusions The activation of GPER-dependant actin cytoskeletonsignaling pathway enhance cell motility in MCF-7R. β1integrin, one oftarget genes of GPER, play a key role in mediating the cell migrationcapacity through regulation of the actin cytoskeleton in the acquiredtamoxifen resistance MCF-7R.