To identify the role and to explore the mechanism of extracellular 5'-nucleotidase (CD73) in human breast cancer growth, CD73 expression was measured firstly in breast cancer tissues and cell lines, and then interfered with or over-expressed by recombinant lentivirus in cell lines. Impacts of CD73 on breast cancer cell proliferation and cell cycle were investigated with colony formation assay, CCK-8 and flow cytometry. The relationship between CD73 and AKT/GSK-3β/β-catenin pathway was assessed with adenosine, adenosine 2A receptor antagonist (SCH-58261), adenosine 2A receptor agonist (NECA), CD73 enzyme inhibitor (APCP) and Akt inhibitor (MK-2206). Moreover, the effect of CD73 on breast cancer growth in vivo was examined with human breast cancer transplanting model of nude mice. The results showed that the expression of CD73 was high in breast cancer tissues and increased with advanced tumor grades and lympho-node status. CD73 expression was higher in more malignant cells, and CD73 overexpression promoted breast cancer cell proliferation in both in vivo and in vitro. It activated AKT/GSK-3β/β-catenin/cyclinD1 signaling pathway through CD73 enzyme activity and other mechanism.

Mir-29 microRNA families are involved in regulation of various types of cancers. Although Mir-29 was shown to play an inhibitory role in tumorigenesis, the role of Mir-29 in breast cancer still remains obscure. In this study, we showed that Mir-29a is the dominant isoform in its family in mammary cells and expression of Mir-29a was down-regulated in different types of breast cancers. Furthermore, over-expression of Mir-29a resulted in significant slower growth of breast cancer cells and caused higher percentage of cells at G0/G1 phase. Consistent with this over-expression data, knockdown of Mir-29a in normal mammary cells lead to higher cell growth rate, and higher percentage of cells entering S phase. We further found that Mir-29a negatively regulated expression of B-Myb, which is a transcription factor associated with tumorigenesis. The protein levels of Cyclin A2 and D1 are consistent with the protein level of B-Myb. Taken together, our data suggests Mir-29a plays an important role in inhibiting growth of breast cancer cells and arresting cells at G0/G1 phase. Our data also suggests that Mir-29a may suppress tumor growth through down-regulating B-Myb.

Multidrug resistance (MDR) is one of the most important factors leading to chemotherapeutic failure in patients with breast cancer. The invasive/metastatic ability of MDR cells is strengthened compared with their parental cells. However, the mechanisms underlying MDR have not been fully elucidated. We found that CD44 and the cellular prion protein (PrPc) were both overexpressed in MDR cells (MCF7/Adr and H69AR). Subsequently, we chose the human breast cancer cell line MCF7/Adr, which is resistant to adriamycin, for further research. We discovered that PrPc physically and functionally interacted with CD44. The knockdown of CD44 or PrPc by siRNA in MCF7/Adr cells inhibited cell migration, invasion and proliferation in vitro. However, when the MCF7/Adr cells transfected with CD44 siRNA were incubated with 10 times the peak plasma concentration (PPC) of taxol, their invasive ability was again enhanced. In the breast-carcinoma tissue samples, a significant correlation between the CD44 expression and the PrPc expression was observed in the postneoadjuvant-chemotherapy (NAC) cases. Moreover, in Group 2, which was unresponsive to NAC, the CD44 and PrPc expression levels were significantly increased in the post-NAC cases compared with the pre-NAC cases using the paired-samples t-test. These data indicate that the CD44/PrPc interaction enhances the malignancy of breast cancer cells and affects the responses to neoadjuvant chemotherapy in breast cancer patients. Therefore, blocking the CD44/PrPc interaction may improve outcomes in chemorefractory breast cancer patients.

BackgroundThe complement system is becoming increasingly recognized as a key participant in many neurodegenerative diseases of the brain. Complement-deficient animals exhibit reduced neuroinflammation.MethodsIn the present study, we administered intracerebroventricularly lipopolysaccharide (LPS) to mimic local infection of the brain and investigated the role of key complement component C3 in brain vasculature endothelial activation and leukocyte recruitment. The degree of neutrophil infiltration was determined by esterase staining. Leukocyte-endothelial interactions were measured using intravital microscopy. Cerebral endothelial activation was evaluated using real-time PCR and Western blotting.ResultsNeutrophil infiltration into the brain cortex and hippocampus was significantly reduced in C3−/− mice and C3aR−/− mice but not in C6−/− mice. We detected markedly attenuated leukocyte-endothelial interactions in the brain microvasculature of C3−/− mice. Accordingly, in response to LPS administration, the brain microvasculature in these mice had decreased expression of P-selectin, E-selectin, intercellular cell adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1). Depletion of C3 from the circulation also caused reduction in VCAM-1 and E-selectin expression and leukocyte recruitment, suggesting that C3 in the circulation contributed to brain endothelial activation. Furthermore, C3−/− mice exhibited decreased leukocyte recruitment into the brain upon tumor necrosis factor-α (TNF-α) stimulation. C3a activated the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) and induced the upregulation of VCAM-1 and ICAM-1 expression in murine primary cerebral endothelial cells in vitro.ConclusionsOur study provides the first evidence that C3a plays a critical role in cerebral endothelial activation and leukocyte recruitment during inflammation in the brain.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-016-0485-y) contains supplementary material, which is available to authorized users.