Cytoplasmic Macrophage Colony-stimulating Factor Induced The Resistance To5-FU And TAX By Upregulating MiR-27a And Activating The APC/β-catenin Signalings In Human Breast Cancer MCF-7Cells

OBJECTIVE: To explore the signalings and mechanism by which cytoplasmicM-CSF induces the resistance to5-FU and TAX in human breast cancer MCF-7cells.METHODS: All kind of cells including MCF-7-M cell, MCF-7-C cell, parent MCF-7cell, and so on were cultured in1640medium. The potential target gene of miR-27awas predicted by bioinformatic software of miRBase and PicTar. The effect ofcytoplasmic M-CSF on expression of APC, β-catenin and downstream genesincluding Survivin, CyclinD1and P-gp was observed by Western blot and RT-PCR inall kind of treated cells. The effect of5-FU and TAX on proliferative activities of allkind of treated cells was measured by MTT. The sensitivity of all kind of treated cellsto5-FU and TAX was evaluated by IC50value. The roles and mechanism ofAPC/β-catenin signslings mediating the ressitance to5-FU and TAX induced bycytoplasmic M-CSF were analyzed when MCF-7-M cells transiently were transfectedby miR-27a antagomir, miR-27a mimic and non-target control, respectively, or werepretreated by FH535, a β-catenin inhibitors.RESULTS: The results from Western blot and RT-PCR indicated that MCF-7-M cellhad a significantly lower expression of APC and a markedly higher expression ofβ-catenin, Survivin, CyclinD1and P-gp either protein or mRNA of these gene thanthat of MCF-7-C cell or MCF-7cell. The protein and mRNA expression of APC wasup-regulated, whereas the protein and mRNA expression of β-catenin, Survivin,CyclinD1and P-gp was down-regulated in miR-27a antagomir tranfected-MCF-7-Mcells, compared with MCF-7-M or non-target control cells. The protein and mRNAexpression of APC was down-regulated, whereas the protein and mRNA expression ofβ-catenin, Survivin, CyclinD1and P-gp was up-regulated in miR-27a mimic tranfected-MCF-7-M cells, compared with MCF-7-M or non-target control cells. Theprotein and mRNA expression of β-catenin, Survivin, CyclinD1and P-gp werereduced in MCF-7-M cells after pretreatment by FH535. The results from MTTshowed that the sensitivity of MCF-7-M cells to5-FU and TAX was markedly lowerthan that of either MCF-7-C cells or MCF-7cells. The sensitivity of miR-27aantagomir tranfected-MCF-7-M cells to5-FU and TAX was significantly incresedthan that of either MCF-7-M cells or non-target control cells, but the sensitivity ofmiR-27a mimic tranfected-MCF-7-M cells to TAX and5-FU was markedlydecreased.CONCLUSION: Cytoplasmic M-CSF inhibited APC expression and induced theexpression of miR-27a, β-catenin, Survivin, CyclinD1and P-gp in human breastcancer MCF-7cells.Cytoplasmic M-CSF incuced the resistance of human breastcancer MCF-7cells to5-FU and TAX by up-regulating miR-27a and activatingAPC/β-catenin signalings...