miR-506 attenuates methylation of lncRNA MEG3 to inhibit migration and invasion of breast cancer cell lines via targeting SP1 and SP3.

BACKGROUND: Breast cancer has been the first death cause of cancer in women all over the world. Metastasis is believed to be the most important process for treating breast cancer. There is evidence that lncRNA MEG3 functions as a tumor suppressor in breast cancer metastasis. However, upstream regulation of MEG3 in breast cancer remain elusive. Therefore, it is critical to elucidate the underlying mechanism upstream MEG3 to regulate breast cancer metastasis. METHODS: We employed RT-qPCR and Western blot to examine expression level of miR-506, DNMT1, SP1, SP3 and MEG3. Besides, methylation-specific PCR was used to determine the methylation level of MEG3 promoter. Wound healing assay and transwell invasion assay were utilized to measure migration and invasion ability of breast cancer cells, respectively. RESULTS: SP was upregulated while miR-506 and MEG3 were downregulated in breast tumor tissue compared to adjacent normal breast tissues. In addition, we found that miR-506 regulated DNMT1 expression in an SP1/SP3-dependent manner, which reduced methylation level of MEG3 promoter and upregulated MEG3 expression. SP3 knockdown or miR-506 mimic suppressed migration and invasion of MCF-7 and MDA-MB-231 cells whereas overexpression of SP3 compromised miR-506-inhibited migration and invasion. CONCLUSIONS: Our data reveal a novel axis of miR-506/SP3/SP1/DNMT1/MEG3 in regulating migration and invasion of breast cancer cell lines, which provide rationales for developing effective therapies to treating metastatic breast cancers.

MicroR-760 suppresses cancer stem cell subpopulation and breast cancer cell proliferation and metastasis: By down-regulating NANOG.

BACKGROUND AND OBJECTIVE: Emerging evidences suggest that cancer stem cells are responsible for tumor aggressive, metastasis and therapeutic resistance. To data, the mechanism underlying breast cancer stem cell (BCSC) population within tumor metastasis remains to be fully elucidated. The current study was to investigate the potential role of microRNA-760 (miR-760) and its associated target gene in population and metastasis of BCSC. METHODS: Characteristic BCSCs surface markers (CD44(+)/CD24(-/low)) were determined by flow cytometry in breast cancer MCF-7 and BT-549 cells. Quantitative RT-PCR was used to evaluate miR-760 and NANOG mRNA expression. Expression of NANOG protein was determined using western blot. Cell proliferation was determined by MTT assay. The model of breast cancer cell xenograft was used to evaluate the effect of miR-760 on tumor growth. RESULTS: BT-549 cell has substantially more CD44(+)/CD24(-/low) subpopulation than MCF-7 cell. Moreover, BT-549 cell expressed lower level of miR-760 and higher level of NANOG than MCF-7cell. By result from cellular miR-760 modulation, we found that miR-760 overexpression suppressed CD44(+)/CD24(-/low) population as well as inhibited cell proliferation and migration of BT-549. On the contrary, knockdown of miR-760 promoted CD44(+)/CD24(-/low) population and migration of MCF-7 cells. By luciferase reporter assay, miR-760 was proved to be functional associated with NANOG via regulating its expression. This functional interaction was showed to be involved in controlling proliferation and migration of MCF-7 and BT-549 cell. CONCLUSION: These data suggest that the target of miR-760/NANOG axis may represent a new therapeutic approach to suppress breast cancer stem cell subpopulation thereby prevent cancer metastasis.

Sox5 induces epithelial to mesenchymal transition by transactivation of Twist1.

The epithelial to mesenchymal transition (EMT), a highly conserved cellular program, plays an important role in normal embryogenesis and cancer metastasis. Twist1, a master regulator of embryonic morphogenesis, is overexpressed in breast cancer and contributes to metastasis by promoting EMT. In exploring the mechanism underlying the increased Twist1 in breast cancer cells, we found that the transcription factor SRY (sex-determining region Y)-box 5(Sox5) is up-regulation in breast cancer cells and depletion of Sox5 inhibits breast cancer cell proliferation, migration, and invasion. Furthermore, depletion of Sox5 in breast cancer cells caused a dramatic decrease in Twist1 and chromosome immunoprecipitation assay showed that Sox5 can bind directly to the Twist1 promoter, suggesting that Sox5 transactivates Twist1 expression. We further demonstrated that knockdown of Sox5 up-regulated epithelial phenotype cell biomarker (E-cadherin) and down-regulated mesenchymal phenotype cell biomarkers (N-cadherin, Vimentin, and Fibronectin 1), resulting in suppression of EMT. Our study suggests that Sox5 transactivates Twist1 expression and plays an important role in the regulation of breast cancer progression.

Insertion/deletion (I/D) in the angiotensin-converting enzyme gene and breast cancer risk: lack of association in a meta- analysis.

PURPOSE: Breast cancer is an important cause of cancer-related death in women. Numerous studies have evaluated the association between the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene and breast cancer risk. However, the specific association is still controversial rather than conclusive. Therefore, we performed a meta-analysis of related studies to address this controversy. METHODS: PubMed, EMBASE, Google Scholar and the Chinese National Knowledge Infrastructure databases were systematically searched to identify relevant studies. A meta-analysis was performed to examine the association between the I/D polymorphism in the ACE gene and susceptibility to breast cancer. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. RESULTS: 10 separate studies of 7 included articles with 10,888 subjects on the relation between the I/D polymorphism in the ACE gene and breast cancer were analyzed by meta-analysis, and our results showed no association between the I/D polymorphism in the ACE gene and breast cancer in total population and different populations. No publication bias was found in the present study. CONCLUSIONS: The ACE I/D polymorphism may not be associated with breast cancer risk. Further large and well-designed studies are needed to confirm this conclusion.

Aplasia Ras homologue member I overexpression induces apoptosis through inhibition of survival pathways in human hepatocellular carcinoma cells in culture and in xenograft.

The aim of the present study was to determine the effects of ARHI (aplasia Ras homologue member I; also known as DIRAS3), a member of the Ras superfamily, on HCC (hepatocellular carcinoma) cells and to define the molecular pathways involved. Stable transfection of ARHI into the HCC cell line Hep3B that lacks expression of this gene reduced cell proliferation significantly as compared with the transfection of empty vector (P<0.01). Moreover, the re-expression of ARHI induced significant apoptosis, whereas a few vector transfectants or non-transfected cells displayed apoptosis. Mechanistically, ARHI restoration impeded the activation of both Akt (also called protein kinase B) and NF-κB (nuclear factor κB). In vivo, restoring ARHI also exerted suppressive effects on xenograft tumour growth, which was coupled with increased apoptosis. Together, these results indicate that ARHI has pro-apoptotic effects on HCC cells, which is associated with the inactivation of both Akt and NF-κB survival pathways.