PMC

TIMP3 protein expression correlates with microRNA-21 content in breast cancer cell lines in vitro. A, Western blot analyses of TIMP3 protein, performed as described in Methods. B, Correlation between miR-21expression and TIMP3 protein levels (Pearson correlation = -0.905; P < 0.05).

Overexpression of miR-21 in breast cancer tissue specimens. Total RNA was isolated from matched normal breast epithelium and breast cancer tissue using Trizol. MiR-21expression was analyzed by TaqMan quantitative real-time PCR and normalized to β-actin expression. A, Quantification of miR-21 expression in matched normal breast epithelium and breast cancer tissue surgically resected from 32 patients. N, normal tissue; T, tumor tissue. B, The ratio of miR-21expression, presented as relative T/N ratio of. The T/N ratios were analyzed statistically in patients with lymph node metastasis or without.*, P < 0.05. n, lymph node metastasis.

miR-21 impacts breast cancer cell invasion in vitro. A, Relative miR-21expression was analyzed by Taqman PCR in four breast cancer cells. B, MDA-231 cells were transfected with miR21, anti-miR-21 or appropriate control oligonucleotides. Total RNA was isolated and analysed for miR-21 expression as in A. C, Cell invasion was quantified by Matrigel assay following transfection of MDA-231 cells with miR21, anti-miR-21 or appropriate control oligonucleotides. The data are standardized against control, and presented as relative cell invasion numbers. D, Relative miR-21 expression in MDA-435 cells transfected with anti-miR-21 or appropriate control oligonucleotides, determined as in A. E, Relative cell invasion numbers in MDA-435 cells transfected with anti-miR-21 or appropriate control oligonucleotides, as in C. The data are representative of three experiments. *, P < 0.05.

miR-21 regulates TIMP3 expression at the mRNA and protein level by targeting the 3'untranslated region of TIMP3 mRNA. A, miR-21 expression was analyzed by TaqMan PCR in MDA-231 and MDA-435 cells following transfection with anti-miR-21 or control oligonucleotides, as in Fig. 2B. B, Relative TIMP3 mRNA expression was analyzed in MDA-231 and MDA-435 cells as described in Methods, following miR-21 silencing as performed in A. C, Western blot analysis of TIMP3 protein expression in MDA-231 and MDA-435 cells following miR-21 silencing as performed in A. D, Quantification of relative TIMP3 protein expression in MDA-231 and MDA-435 cells following miR-21 silencing, as performed in A. E, Generation of cDNA encoding the 3'UTR region of TIMP3 containing a miR-21 binding site. cDNA was subsequently cloned into a Luciferase reporter plasmid. F, Determination of the impact of miR-21 silencing on pGL3-TIMP3 luciferase expression in MDA-231 and MDA-435 cells. Data represents two independent experiments performed in triplicate.*, P < 0.05.