PVT1-derived miR-1207-5p promotes breast cancer cell growth by targeting STAT6.

Accumulating evidence indicates that ectopic expression of non-coding RNAs are responsible for breast cancer progression. Increased non-coding RNA PVT1, the host gene of microRNA-1207-5p (miR-1207-5p), has been associated with breast cancer proliferation. However, how PVT1 functions in breast cancer is still not clear. In this study, we show a PVT1-derived microRNA, miR-1207-5p, that promotes the proliferation of breast cancer cells by directly regulating STAT6. We first confirm the positive correlated expression pattern between PVT1 and miR-1207-5p by observing consistent induced expression by estrogen, and overexpression in breast cancer cell lines and breast cancer patient specimens. Moreover, silence of PVT1 also decreased miR-1207-5p expression. Furthermore, increased miR-1207-5p expression promoted, while decreased miR-1207-5p expression suppressed, cell proliferation, colony formation, and cell cycle progression in breast cancer cell lines. Mechanistically, a novel target of miR-1207-5p, STAT6, was identified by a luciferase reporter assay. Overexpression of miR-1207-5p decreased the levels of STAT6, which activated CDKN1A and CDKN1B to regulate the cell cycle. We also confirmed the reverse correlation of miR-1207-5p and STAT6 expression levels in breast cancer samples. Therefore, our findings reveal that PVT1-derived miR-1207-5p promotes the proliferation of breast cancer cells by targeting STAT6, which in turn controls CDKN1A and CDKN1B expression. These findings suggest miR-1207-5p might be a potential target for breast cancer therapy.

CyclinD1 Is a New Target Gene of Tumor Suppressor MiR-520e in Breast Cancer.

OBJECTIVE: To investigate the involvement of miR-520e in the modulation of cancer-promoting cyclinD1 in breast cancer. METHODS: A reverse transcription-polymerase chain reaction (RT-PCR) was applied to test the regulation of miR-520e on cyclinD1. The binding of miR-520e to 3'-untranslated region (3'UTR) of cyclinD1 mRNA was predicted by an online bioinformatics website. The effect of miR-520e on the luciferase reporters with binding sites of miR-520e and 3'UTR of cyclinD1 mRNA was revealed using a luciferase reporter gene assay. The correlation between miR-520e and cyclinD1 in clinical breast cancer samples was detected through quantitative real-time PCR. RESULTS: The expression of cyclinD1 was gradually reduced as the dose of miR-520e increased. Anti-miR-520e obviously induced cyclinD1 in breast cancer cells. After anti-miR-520e was introduced into the cells, the inhibition of cyclinD1 expression mediated by miR-520e was reversed. The binding of miR-520e with cyclinD1 was revealed via bioinformatics. Under the treatment of dose-increasing miR-520e or anti-miR-520e, the luciferase activities of cyclinD1 3'UTR vector were lower or higher by degrees. However, the activity of the mutant vector was not affected at all. Finally, in clinical breast cancer tissues the negative correlation of miR-520e with cyclinD1 was revealed. CONCLUSION: In conclusion, cyclinD1 is a new target of miR-520e in breast cancer.

[Correlation between the activation of AP-1 signal transduction pathway and metastasis of colorectal carcinoma].

OBJECTIVE: To investigate the binding activity of activator protein-1 (AP-1) with DNA probe in the colorectal carcinoma (CRC) tissues and surrounding tissues and explore the correlation between the activation of AP-1 signal transduction pathway and metastasis of CRC. METHODS: The AP-1 DNA binding activities were investigated by electrophoretic mobility shift assay (EMSA) in CRC specimens (T), surrounding tissues including 2 cm (P(2)), 5 cm(P(5)) far away from primary tumor margin and distal resection margin of the specimens (N). The mRNA expression level of vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9) were measured by quantitive reverse transcription polymerase chain reaction (Q- RT-PCR). RESULTS: The AP-1 DNA binding activity in T was significantly higher than those in P(2), P(5) and N (P< 0.05) tissues. There were significantly positive correlations between AP-1 DNA binding activity in tumor and invasive degree, lymphatic metastasis respectively (P< 0.01), but no correlation with histological classification and differentiation (P> 0.05). The transcription levels of VEGF and MMP-9 in CRC were significantly higher than those in P(5) and N (P< 0.01, P< 0.05) tissues. The transcription levels of VEGF and MMP-9 were significantly correlated with increasing AP-1 DNA binding activity (P< 0.01). CONCLUSIONS: AP-1 is significantly correlated to the invasion and metastasis in CRC. The activation of AP-1 signal transduction pathway might be involved in the angiogenesis and of degradation extracellular matrix during tumor metastasis.