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Background: Altered microRNAs expression mediates tumor development and progression in many type cancers including triple negative breast cancer (TNBC). Here we detected the effect of miR-454 on cell proliferation, migration and invasion of triple negative breast cancer cells. Results: miR-454 promoted the proliferation of TNBC, and enhanced migration and invasion in TNBC cells. Meanwhile, miR-454 improved the survival of TNBC cells after ironizing radiation. miR-454 inhibited radiation-induced apoptosis in TNBC cells by regulation of caspase 3/7 and Bcl-2 expression. Furthermore, PTEN and pAKT levels in TNBC cells were changed after overexpression of miR-454. Conclusions: miR-454 played an essential role in tumor development and progression in TNBC, and might be used as a potential biomarker to predict radiotherapy response and prognosis in TNBC. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the antitumor effect of celecoxib (CXB) combined with doxorubicin (DOX) on the subcutaneous xenograft tumor of medullary thyroid carcinoma in nude mice, and to analyze the possible mechanism of action. Nude mice with xenografted medullary thyroid carcinoma (MTC) were randomly divided into the control, CXB, DOX and DOX plus CXB groups, and the drug treatment was administered for three weeks. It was found that the tumor inhibition rates and the apoptosis index in the treatment groups were higher than in the control group (P<0.01), and that these values were higher in the combination group compared with the single-drug group (P<0.01). DOX alone upregulated the cyclooxygenase-2 and multidrug-resistance 1 expression levels, and the combination of CXB and DOX or CXB alone notably decreased the expression level of the two proteins compared with no treatment. The results of the present study provide evidence that a combination of DOX and CXB is a potential drug candidate for the treatment of MTC. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the mechanisms of the antitumor effect of celecoxib (CXB) in the treatment of human medullary thyroid carcinoma (MTC). Human MTC TT cells were cultured with different concentrations (0, 20, 40, 60 μmol/l) of CXB following 0-72 h in vitro. An MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay was used to determine the growth inhibition of MTC in vitro. Flow cytometry was performed to analyze the cell cycle of TT cells. Levels of prostaglandin E2 (PGE2) were measured by enzyme-linked immunosorbent assay (ELISA) method. The expression profile of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) was measured by western blot analysis. In the present study, it was identified that CXB inhibited TT cell proliferation and induced apoptosis in a dose- and time-dependent manner. The cell cycle was arrested at G0/G1 and the percentage of cells in S phase was markedly decreased. The expression levels of PGE2 were inhibited by CXB. CXB effectively downregulated the expression of COX-2 and VEGF in a dose- and time-dependent manner. These data demonstrated that CXB inhibited the proliferation of MTC TT cells in vitro and thus may be effective as an antitumor therapy for human MTC. [ABSTRACT FROM AUTHOR]