The investigation of circRNA profiling reveals the regulatory role of the hsa_circ_0000375/miR-7706 pathway in breast cancer.

BACKGROUND: Circular RNAs (circRNAs) take an effect on tumorigenesis and progression. However, circRNAs have not been systematically identified in breast cancer (BC) as crucial regulators in multitudinous biological processes. This study is conducted to explore novel circRNAs in BC and the corresponding mechanisms of their action. METHODS: The circRNA expression profile and RNA-sequencing data about BC were respectively downloaded from public database. Differentially expressed circRNAs, miRNAs, and mRNAs were identified by fold change filtering. The competing endogenous RNAs (ceRNAs) network was established based on the relationship between circular RNAs, miRNAs and mRNAs. GO and KEGG enrichment analysis of the overlapped genes were carried out to predict the potential functions and mechanisms of circRNAs in BC. The CytoHubba plugin in Cytoscape was applied to identify the hub genes from the PPI regulatory network. Kaplan-Meier plotter was used to perform survival analysis of these hub genes further. Real-time PCR was performed to test the expression of circRNA in BC tissues. Cell function studies including transwell analysis and CCK-8 analysis were used to investigate circRNAs' biological functions. RESULTS: A total of seven circRNAs exhibiting differential expression were identified in this study. After the intersection between the predicted target miRNA and the down-regulated differential miRNAs (DEmiRNAs), circRNA-miRNA interactions involving 3 circRNAs and 4 miRNAs were identified. Venn diagram was utilized to intersect the predicted target genes of the 4 miRNAs and the down-regulated differential genes in BC, and 149 overlapped genes were screened out ulteriorly. Additionally, we built a protein-protein interaction (PPI) network and selected six hub genes. Moreover, the survival data of BC patients suggested that low expression of ADIPOQ, LPL and LEP were significantly correlated with poor prognosis. Results from real-time PCR indicated that hsa_circ_0000375 was significantly down-regulated in breast cancer tissues. Functional in vitro experiments showed that over-expression of hsa_circ_0000375 can restrain proliferation, migration and invasion abilities of breast cancer cells. Further verification indicated that hsa_circ_0000375 exerted its anti-oncogene effect via sponge of miR-7706. CONCLUSIONS: This study constructed and analyzed a circRNA-associated ceRNA regulatory network and uncovered that hsa_circ_0000375 exerted its anti-oncogene effect via sponge of miR-7706.

KIF20A is a Prognostic Marker for Female Patients with Estrogen Receptor-Positive Breast Cancer and Receiving Tamoxifen as Adjuvant Endocrine Therapy.

Purpose: Our aim was to verify whether KIF20A has the potential to serve as a prognostic marker for female patients with estrogen receptor (ER)-positive breast cancer (BC) and treated with tamoxifen (TAM). Patients and Methods: Online tools were used to investigate the potential correlation between KIF20A gene expression and survival of patients with ER-positive BC and TAM treatment. Furthermore, immunohistochemistry (IHC) was conducted to assess the expression levels of KIF20A in patients included from our center. The prognostic value of KIF20A for disease-free survival (DFS) and overall survival (OS) was further evaluated using Cox regression analysis. Results: According to the results obtained from online tools, it was found that patients with low KIF20A expression exhibited significantly better survival outcomes in terms of relapse-free survival (RFS), distant metastasis-free survival (DMFS), and OS compared to those with high KIF20A expression (P < 0.001, P < 0.001, and P = 0.008, respectively). Additionally, significantly lower gene expression of KIF20A was found in patients who responded to TAM than in those who did not respond to TAM (P < 0.001). We further included 203 patients with adjuvant TAM therapy, and IHC for KIF20A was performed on sections from paraffin-embedded blocks. Patients with low KIF20A expression had significantly better DFS and OS (P = 0.001 and 0.002, respectively, log rank test), and the expression of KIF20A was identified as an independent factor for predicting both DFS and OS (P = 0.001 and 0.008, respectively). Conclusion: KIF20A expression is an independent prognostic factor for survival in patients with ER-positive BC who received adjuvant TAM therapy. In clinical practice, IHC evaluation of KIF20A expression in surgical samples before administering tamoxifen may assist in predicting the treatment outcomes of these patients.

High expression of autophagy-related gene EIF4EBP1 could promote tamoxifen resistance and predict poor prognosis in breast cancer.

BACKGROUND: Breast cancer (BC) remains a public health problem. Tamoxifen (TAM) resistance has caused great difficulties for treatment of BC patients. Eukaryotic translation initiation factor 4E binding protein 1 (EIF4EBP1) plays critical roles in the tumorigenesis and progression of BC. However, the expression and mechanism of EIF4EBP1 in determining the efficacy of TAM therapy in BC patients are still unclear. AIM: To investigate the expression and functions of EIF4EBP1 in determining the efficacy of TAM therapy in BC patients. METHODS: High-throughput sequencing data of breast tumors were downloaded from the Gene Expression Omnibus database. Differential gene expression analysis identified EIF4EBP1 to be significantly upregulated in cancer tissues. Its prognostic value was analyzed. The biological function and related pathways of EIF4EBP1 was analyzed. Subsequently, the expression of EIF4EBP1 was determined by real-time reverse transcription polymerase chain reaction and western blotting. Cell Counting Kit-8 assays, colony formation assay and wound healing assay were used to understand the phenotypes of function of EIF4EBP1. RESULTS: EIF4EBP1 was upregulated in the TAM-resistant cells, and EIF4EBP1 was related to the prognosis of BC patients. Gene Set Enrichment Analysis showed that EIF4EBP1 might be involved in Hedgehog signaling pathways. Decreasing the expression of EIF4EBP1 could reverse TAM resistance, whereas overexpression of EIF4EBP1 promoted TAM resistance. CONCLUSION: This study indicated that EIF4EBP1 was overexpressed in the BC and TAM-resistant cell line, which increased cell proliferation, invasion, migration and TAM resistance in BC cells.

Role of PAX2 in breast cancer verified by bioinformatics analysis and in vitro validation.

Background: Breast cancer (BC) is the most frequently diagnosed cancer in women and the second most common cancer among newly diagnosed cancers worldwide. Studies have shown that paired box 2 (PAX2) participates in the tumorigenesis of some cancer cells, but its role in BC is still unclear. Methods: Transcriptome expression profiles and clinicopathological information of BC were downloaded from The Cancer Genome Atlas (TCGA) database to explore the expression level and prognostic value of PAX2. Gene set enrichment analysis (GSEA) and functional enrichment analysis were performed to investigate the functions and pathways of PAX2. Moreover, real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) was used to determine the expression of PAX2 in BC tissues, and the predictive value of PAX2 in clinical samples was assessed. Cell Counting Kit-8 (CCK-8) assay was used to evaluate cell growth. The migration and invasive capacities of cells were assessed by wound healing assay and Transwell assay. Results: PAX2 was upregulated in the TCGA-BC datasets. GSEA suggested that PAX2 may be involved in the regulation of signaling pathways such as MAPK. Moreover, PAX2 was overexpressed in BC tissues, and PAX2 expression was associated with tumor size and lymph node metastasis. PAX2 deficiency could promote the growth, migration, and invasion of BC cells. Conclusions: Upregulation of PAX2 inhibited BC cell growth, migration, and invasion, making PAX2 a potential therapeutic target for BC.

Role of locoregional surgery in patients with de novo stage IV breast cancer: analysis of real-world data from China.

Stage IV breast cancer is metastatic breast cancer (MBC). Because real-world data are lacking in China, our research attempts to explore the effect of locoregional surgery on the prognosis of patients with MBC. A total of 987 patients from 10 hospitals and 2 databases in East China (2004-2018) were included in this study. Overall, 47% of patients underwent locoregional surgery, and 53% did not. Surgeons tended to perform surgery on patients with small tumours (T1/T2), positive hormone receptor (HR) markers, and metastatic sites confined to a single organ and non-visceral sites (bone only/others) (each p < 0.05). Kaplan-Meier survival curves and the log-rank test showed that median survival was longer for patients who had locoregional surgery than for those who did not (45.00 vs. 28.00 months; p < 0.001). Patients who underwent surgery after systemic treatment had better survival than those who underwent surgery immediately (p < 0.001). In most subgroups, overall survival (OS) was significantly longer in the surgery group than in the no-surgery group (each p < 0.05), except for brain metastases and triple negative breast cancer. Therefore, we concluded that locoregional surgery for the primary tumour in MBC patients was associated with a marked reduction in risk of dying except for patients with brain metastases or triple-negative subtype.

Identification of core genes and potential molecular mechanisms in breast cancer using bioinformatics analysis.

BACKGROUND: Breast cancer is the most frequently diagnosed cancer in women worldwide. This study aimed to elucidate the potential key candidate genes and pathways in breast cancer. METHODS: The gene expression profile dataset GSE65212 was downloaded from GEO database. Differentially expressed genes (DEGs) were obtained by the R Bioconductor packages. The Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs were performed using DAVID database. The protein-protein interaction (PPI) network was then established by STRING and visualized by Cytoscape software. Module analysis of the PPI network was performed by the plug-in Molecular Complex Detection (MCODE). Then, the identified genes were verified by Kaplan-Meier plotter online database and quantitative real-time PCR (qPCR) in breast cancer tissue samples. RESULTS: A total of 857 differential expressed genes were identified, of which, the upregulated genes were mainly enriched in the cell cycle, while the downregulated genes were mainly enriched in PPAR signaling pathway. Moreover, six hub genes with high degree were identified, including TOP2A, PCNA, CCNB1, CDC20, BIRC5 and CCNA2. Lastly, the Kaplan-Meier plotter online database confirmed that higher expression levels of these hub genes were related to lower overall survival. Experimental validation showed that all six hub genes had the same expression trend as predicted. CONCLUSION: These results identified key genes, which could be used as a new biomarker for breast cancer diagnosis and treatment.