Role of miR-301b-3p/5p in breast cancer: A study based on the cancer GenomeAtlas program (TCGA) and bioinformatics analysis.

Background: Breast cancer is one of the most common cancer type of women in the world. miR-301b-3p/5p were paired miRNAs derived from the same pre-miRNA, which may have different clinical roles in tumor and requires more exploration and research. Methods: In order to investigate the differential expression, clinical significance, diagnostic and prognostic value of miR-301b-3p/5p and explore their function in breast cancer, we extracted information of miRNAs from TCGA data sets for clinical correlation analysis, and the potential function was explored by GO、KEGG enrichment and immunoinfiltration analysis. Results: miR-301b-3p/5p were both highly expressed in breast cancer, there is a positive correlation between them. miR-301b-3p and miR-301b-5p have different clinical features. In breast cancer, miR-301b-3p can be used as a potential diagnostic marker while miR-301b-5p can be used as a prognostic molecule. GO, KEGG enrichment and immunoinfiltration analysis reveals that miR-301b-3p focuses on molecular functions, miR-301b-5p focuses on regulation of angiogenesis, and it is correlated with immune cells. Conclusions: miR-301b-3p and miR-301b-5p are both tumor promoter in breast cancer, miR-301b-3p can be used as a potential diagnostic marker, while miR-301b-5p can be used as a prognostic molecule and an underlying therapy target. Although miR-301b-3p/5p is a pair of miRNAs from two arms of the same pre-miRNA, they may promote the progression of breast cancer together through different pathway.

Genes That Predict Poor Prognosis in Breast Cancer via Bioinformatical Analysis.

BACKGROUND: Breast cancer is one of the most commonly diagnosed cancers all over the world, and it is now the leading cause of cancer death among females. The aim of this study was to find DEGs (differentially expressed genes) which can predict poor prognosis in breast cancer and be effective targets for breast cancer patients via bioinformatical analysis. METHODS: GSE86374, GSE5364, and GSE70947 were chosen from the GEO database. DEGs between breast cancer tissues and normal breast tissues were picked out by GEO2R and Venn diagram software. Then, DAVID (Database for Annotation, Visualization, and Integrated Discovery) was used to analyze these DEGs in gene ontology (GO) including molecular function (MF), cellular component (CC), and biological process (BP) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway. Next, STRING (Search Tool for the Retrieval of Interacting Genes) was used to investigate potential protein-protein interaction (PPI) relationships among DEGs and these DEGs were analyzed by Molecular Complex Detection (MCODE) in Cytoscape. After that, UALCAN, GEPIA (gene expression profiling interactive analysis), and KM (Kaplan-Meier plotter) were used for the prognostic information and core genes were qualified. RESULTS: There were 96 upregulated genes and 98 downregulated genes in this study. 55 upregulated genes were selected as hub genes in the PPI network. For validation in UALCAN, GEPIA, and KM, 5 core genes (KIF4A, RACGAP1, CKS2, SHCBP1, and HMMR) were found to highly expressed in breast cancer tissues with poor prognosis. They differentially expressed between different subclasses of breast cancer. CONCLUSION: These five genes (KIF4A, RACGAP1, CKS2, SHCBP1, and HMMR) could be potential targets for therapy in breast cancer and prediction of prognosis on the basis of bioinformatical analysis.

Long non­coding RNA TTN­AS1 regulates the proliferation, invasion and migration of triple­negative breast cancer by targeting miR­211­5p.

Increasing evidence has demonstrated that long non­coding RNAs (lncRNAs) serve important roles in numerous malignancies, including triple­negative breast cancer (TNBC). The lncRNA titin­antisense RNA1 (TTN­AS1) has previously been reported to promote tumorigenesis in various types of cancer. The present study aimed to investigate the potential role of TTN­AS1 in breast cancer and the associated underlying mechanisms. Following prediction by Starbase and confirmation by dual­luciferase reporter assay, TINCR was demonstrated to be a target gene for microRNA (miR)­211­5p. The expression levels of TTN­AS1 and miR­211­5p, which was predicted to be targeted by TTN­AS1, in TNBC tissues and in the breast cancer cell lines MDA­MB­453 and MDA­MB­231 were measured using reverse transcription­quantitative PCR. Following TTN­AS1­knockdown, cell proliferation was measured using a Cell Counting Kit­8 assay and colony formation assay, whereas cell invasion and migration were measured using Transwell and wound healing assays, respectively. Luciferase reporter assay was performed to verify the potential interaction between TTN­AS1 and miR­211­5p. In addition, rescue assays were conducted to investigate the effects of TTN­AS1 and miR­211­5p on TNBC development. The results demonstrated that TTN­AS1 expression was significantly upregulated, whereas that of miR­211­5p was found to be downregulated in TNBC tissues and cell lines compared with the matched adjacent normal tissues and normal breast epithelial cell line MCF­10A, respectively. Furthermore, TTN­AS1­knockdown inhibited the proliferation and invasive and migratory abilities of MDA­MB­453 and MDA­MB­231 cells, which was reversed following co­transfection with the miR­211­5p inhibitor. The results from luciferase reporter assay confirmed that miR­211­5p was a direct target of TTN­AS1, suggesting that TTN­AS1 may bind directly to miR­211­5p to negatively regulate its expression. In conclusion, the findings from the present study demonstrated that TTN­AS1 regulated the proliferation and invasive and migratory abilities of TNBC by targeting miR­211­5p. This study may provide some insights into the regulatory mechanism of TNBC and help the development of novel therapeutic interventions for TNBC.

SPARC inhibits breast cancer bone metastasis and may be a clinical therapeutic target.

Breast cancer is one of the most common types of cancer in females worldwide, and metastasis to bone is an important characteristic of malignancy. The present study aimed to investigate the molecular mechanism of breast cancer to bone metastasis of secreted protein acidic and rich in cysteine (SPARC). Immunohistochemistry was performed to examine the expression of SPARC in primary breast tumors and bone metastatic foci. Western blotting and reverse transcription-quantitative polymerase chain reaction were performed to detect the expression level of SPARC in several types of breast cancer cell. A Transwell filter assay was used to assess the effect of SPARC on breast cancer cell invasion ability, and an osteoblast differentiation assay was employed to analyze the effect of SPARC on the differentiation ability of mesenchymal stem cells. Clinical data revealed that decreased stromal SPARC expression is associated with breast cancer to bone metastasis. Gain- and loss-of-function studies reveal that SPARC inhibits the migration and invasion of breast cancer cells, and suppresses osteoclast activation in the breast cancer microenvironment. SPARC serves an important role in breast cancer bone metastasis and may be a promising therapeutic target for the treatment of breast cancer bone metastasis.

Bioinformatic analysis of computational identified differentially expressed genes in tumor stoma of pregnancy­associated breast cancer.

The present study aimed to screen the differentially expressed genes (DEGs) in tumor­associated stroma of pregnancy­associated breast cancer (PABC). By analyzing Affymetrix microarray data (GSE31192) from the Gene Expression Omnibus database, DEGs between tumor asso-ciated stromal cells and normal stromal cells in PABC were identified. Gene Ontology (GO) function and pathway enrichment analyses for the DEGs were then performed, followed by construction of a protein­protein interaction (PPI) network. A total of 94 upregulated and 386 downregulated DEGs were identified between tumor associated stromal cells and normal stromal cells in patients with PABC. The upregulated DEGs were primarily enriched in the cytokine­cytokine receptor interaction pathway and GO terms associated with the immune response, which included the DEGs of interleukin 18 (IL18) and cluster of differentiation 274 (CD274). The downregulated DEGs were primarily involved in GO terms associated with cell surface receptor linked signal transduction and pathways of focal adhesion and pathways in cancer. In the PPI network, nodes of jun proto­oncogene (JUN), FBJ murine osteosarcoma viral oncogene homolog (FOS), V­myc avian myelocytomatosis viral oncogene homolog (MYC), and alpha­smooth muscle actin (ACTA2) had higher degrees. The hub genes of JUN, FOS, MYC and ACTA2, as well as the DEGs IL18 and CD274 that were associated with the immune response in GO terms may exert important functions in the molecular mechanisms of PABC. These genes may be used as new molecular targets in the treatment of this disease.

miRNA expression patterns in chemoresistant breast cancer tissues.

BACKGROUND/AIMS: Breast cancer chemoresistance is a major obstacle to the successful treatment of patients. miRNAs perform critical roles in biological processes, including tumorigenesis and chemoresistance. However, little clinical data are available regarding the relationship between miRNA expression patterns and breast cancer chemoresistance. METHODS: We created a doxorubicin-resistant MCF-7 (MCF-/Adr) cell line using a pulse-selection method; then verified the resistance of the MCF-7/Adr cell line to doxorubicin by using the methyl thiazolyl tetrazolium (MTT) assay, terminal deoxyribonucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) staining, and Intracellular doxorubicin accumulation assay. Then, we performed qRT-PCR to detect the expression patterns of 14 selected miRNAs (which are related to breast cancer resistance) in both cell lines. Subsequently, we performed a bioinformatics analysis, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, to determine the putative functions of 13 differentially expressed miRNA-targeted genes. Finally, we tested the expression levels of these 13 miRNAs in 10 chemotherapy non-responder breast cancer tissues and 29 responder tissues. All statistical analyses were performed by a two-tailed Student's t-test, and a P value less than 0.05 was considered statistically significant. RESULTS: The results of the MTT assay showed that the MCF-7/Adr cell line was significantly more resistant to doxorubicin compared to the MCF-7 cells The results of the TUNEL assay indicated that doxorubicin induced an increase in the number apoptotic cells in the MCF-7 group. Additionally, the accumulation of doxorubicin was higher in MCF-7 cells compared to MCF-7/Adr cells, which was consistent with the MTT and TUNEL results. The qRT-PCR results demonstrated that compared to the parental MCF-7 cell line, miR-200a, miR-141, miR-200c, miR-31, miR-429, and miR-196b were over-expressed, and let-7e, miR-576-3p, miR-125b-1, miR-370, miR-145, miR-765, and miR-760 were significantly down-regulated in MCF-7/Adr cells. The GO analysis results revealed that the predicted target genes of these 14 miRNAs primarily regulated protein binding, zinc ion binding, DNA binding, and transcription factor activity. The KEGG data demonstrated that these target genes are mainly involved in the MAPK signaling pathway, regulation of the actin cytoskeleton, cytokine-cytokine receptor interaction, and other signaling pathways. Compared to the breast cancer tissues from chemotherapy responders, 10 miRNAs were identified to be dysregulated in the chemoresistant breast cancer tissues. Three of these miRNAs were up-regulated (miR-141, miR-200c, and miR-31), and 7 were down-regulated (let-7e, miR-576-3p, miR-125b-1, miR-370, miR-145, miR-765, and miR-760). CONCLUSION: In this study, we identified 10 dysregulated miRNAs in both breast cancer cells and chemoresistant tissues, which might be biomarkers for the prognosis of breast cancer chemoresistance. Our study contributes to a comprehensive understanding of prognostic biomarkers during clinical treatment, and we hypothesize that the miRNA signatures of drug-resistant carcinoma tissues could be useful for developing new strategies for targeted therapies in patients with chemoresistant breast cancer.