##P<0

##P<0.01, One-way ANOVA compared to matched NC or Mock. (TIF) Reduction in miR-150 suppresses tumor growth in MDA-MB-231 cells xenografts implanted in BALB/c-nu mice.(A) Representative photographs of the tumors of each group from two independent experiments. to inhibit miR-150 invitro, and the result demonstrates that the 3-untranslated region (3UTR) of P2X7receptor contains a highly conserved miR-150-binding motif and its direct interaction with miR-150 down-regulates endogenous P2X7protein levels. Furthermore, our findings demonstrate that miR-150 over-expression promotes growth, clonogenicity and reduces apoptosis in breast cancer cells. Meanwhile, these findings can be decapitated in nude mice with breast cancer xenografts. Finally, these observations strengthen our working hypothesis that up-regulation of miR-150 in breast cancer is inversely associated with P2X7receptor expression level. Together, these findings establish miR-150 as a novel regulator of P2X7and a potential therapeutic target for breast cancer. == Introduction == Breast cancer is the most common cancer afflicting women around Quetiapine fumarate the world[1], and distal metastasis of highly invasive breast cancer cells is the major cause of death in these women. Recently, the classical categories of oncogenes and tumor suppression genes have been expanded to include a new family of RNAs known as microRNAs (miRNAs), which may regulate a large number of protein-coding genes, including tumor-related genes. miRNAs are a class of endogenous 2224 nt non-coding single-stranded RNA molecules that regulate gene expression post-transcriptionally. miRNAs can affect multiple cell processes including proliferation, apoptosis, differentiation, angiogenesis, and development[2],[3]. Not only do they inhibit translation of their target genes, they also degrade the target Quetiapine fumarate mRNAs through recognition of imperfect complementary sites, usually located in the 3-untranslated regions (3UTR) of the target mRNAs, endowing miRNAs with the capacity to regulate numerous biological processes. Loss or gain of function of specific miRNAs contributes to tumorigenesis and cancer progression. miR-150, a hematopoietic cell-specific miRNA, was shown to affect B-cell differentiation and development[4]. Most of the studies have indicated that miR-150 is significantly over-expressed in multiple kinds of cancers, including malignant lymphoma, and gastric, lung, endometrial, and pancreatic cancers[5],[6],[7],[8], and displays various effects on cellular proliferation, differentiation, apoptosis, migration, and invasion. In recent years, important advances have been made in the knowledge of functions and mechanisms of miR-150 in various human tumors, and several important targets, such as c-myb[4], EGR2[6], MUC4[7], P2X7[8], AKT2[9]and CXCR4[10]have been identified and experimentally tested for their functional participation in IL1-BETA the disease process. However, little is known about the expression and biological role of miR-150 in breast cancer. The receptor P2X7is the main physiological pro-apoptotic mechanism in epitheliain vivo. P2X7receptor is a glycosylated G-coupled-membrane-bound receptor protein[10], and its natural ligand is ATP[11]. Binding of P2X7receptor by ATP can stimulate various signaling pathways including the TNF-a, TRAIL, p38, JNK/stress activated protein kinase (SAPK) and NF-B cascades, which can induce Quetiapine fumarate proliferation, differentiation and apoptosis[12],[13]. Early studies reported on the effect of P2X7receptor in inflammation[14]. Recent studies focused on the effects of P2X7receptor activation in tumor cells. In epithelia derived from the ectoderm, decreased levels of P2X7receptor in the urogenital sinus and the distal paramesonephric duct are associated with cancer development[15]. P2X7receptor expression can be modulated by factors that regulate transcription, post-translational modification, and glycosylation of the receptor[16],[17],[18]. These effects regulate the growth and proliferation of epithelial cells, and possibly control the development of epithelial cancersin vivo. P2X7transcription may be regulated by miR-150 in uterine epithelial cells[8]. In the present study, we have investigated the role of miR-150 in the regulation of P2X7receptor expression in breast cancer cells. Our findings demonstrated that the 3UTR of P2X7receptor contains a putative binding Quetiapine fumarate site for miR-150, which is highly conserved across several mammalian species. Furthermore, we experimentally showed that miR-150 directly targets the 3UTR of P2X7to suppress its expression. miR-150 stimulates a decrease in P2X7mRNA steady-state levels by targeting instability sites within the 3UTR of the P2X7gene. These data suggested that the reduced expression of P2X7in cancer epithelial cells is the.