HORMA domain-containing protein 1 (HORMAD1), is normally expressed only in the germline, but is frequently re-activated in human triple-negative breast cancer (TNBC); however, its function in TNBC is largely unknown. In the present study, the expression and biological significance of HORMAD1 in human TNBC was evaluated. Bioinformatics analysis and reverse transcription-quantitative PCR were used to evaluate HORMAD1 expression in datasets and cell lines. HORMAD1 protein expression was detected in TNBC samples using immunohistochemical assays, and the effect of HORMAD1 on cell proliferation was determined using Cell Counting Kit-8, plate colony formation and standard growth curve assays. Cell cycle, reactive oxygen species (ROS) and apoptosis analyses were conducted using flow cytometry. The activity of caspases was measured using caspase activity assay kit. The levels of key apoptosis regulators and autophagy markers were detected by western blot analysis. TNBC cell survival and apoptosis were not influenced by small interfering RNA targeting HORMAD1 alone; however, HORMAD1 knockdown enhanced autophagy and docetaxel (Doc)-induced apoptosis, compared with the control group. Furthermore, higher ROS levels and caspase-3, -8 and -9 activity were detected in MDA-MB-436 TNBC cells with HORMAD1 knockdown upon exposure to Doc. The levels of the induced DNA damage marker γH2AX were also higher, while those of the DNA repair protein RAD51 were lower in TNBC cells with HORMAD1 knockdown compared with the controls. Furthermore, the expression of the autophagy marker P62 was enhanced in MDA-MB-231 cells in response to HORMAD1 overexpression. Notably, Doc-induced apoptosis was similarly increased by both HORMAD1 overexpression and treatment with the autophagy inhibitor, 3-methyladenine (3MA); however, the Doc-induced increase in autophagy was not inhibited by 3MA. The present data indicated that HORMAD1 was involved in autophagy and that the inhibition of autophagy can partially enhance the induction of apoptosis by Doc. The role of HORMAD1 in the DNA damage tolerance of tumor cells may be the main reason for Doc resistance; hence, HORMAD1 could be an important therapeutic target in TNBC.

Background Recent studies have indicated that serpin peptidase inhibitor, clade A, member 3 (SERPINA3) is a potential marker associated with tumor progression, which connoted that SERPINA3 is related to malignant phenotypes in cancer. However, the biological function of SERPINA3 in breast cancer (BC) remains unclear. Methods Bioinformatics data were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Immunohistochemical staining (IHC) was conducted to determine SERPINA3 expression. With strong aggressive abilities, triple-negative breast cancer (TNBC) cell lines (MDA-MB-231, BT549 and MDA-MB-436) were obtained to examine SERPINA3 expression and functions. Wound healing and Transwell assays were performed to measure cell migration and invasion. Cell Counting Kit-8 (CCK-8) assay was conducted to detect cell proliferation abilities and cell viabilities. Results SERPINA3 was upregulated in BC tissues. Functional assays suggested that overexpression of SERPINA3 significantly promoted cell proliferation, where migration and invasion of TNBC cells were accelerated. Knockdown of SERPINA3 had the opposite effects. These results causing by overexpression of SERPINA3 were also confirmed in non-TNBC cell lines. Overexpression of SERPINA3 remarkably enhanced the epithelial–mesenchymal transition (EMT) by upregulating the EMT markers and EZH2. In addition, the overexpression of SERPINA3 reduced the sensitivity of TNBC cells to cisplatin. Conclusion SERPINA3 can regulate the migration, invasion and EMT of TNBC cells and increased expression of SERPINA3 confers resistance to cisplatin in TNBC cells. We discern it is required for the regulation of BC progression and is a critical target for the clinical treatment of BC.

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This study is aimed at exploring the potential mechanism of angiogenesis, a biological process-related gene in breast cancer (BRCA), and constructing a risk model related to the prognosis of BRCA patients. We used multiple bioinformatics databases and multiple bioinformatics analysis methods to complete our exploration in this research. First, we use the RNA-seq transcriptome data in the TCGA database to conduct a preliminary screening of angiogenesis-related genes through univariate Cox curve analysis and then use LASSO regression curve analysis for secondary screening. We successfully established a risk model consisting of seven angiogenesis-related genes in BRCA. The results of ROC curve analysis show that the risk model has good prediction accuracy. We can successfully divide BRCA patients into the high-risk and low-risk groups with significant prognostic differences based on this risk model. In addition, we used angiogenesis-related genes to perform cluster analysis in BRCA patients and successfully divided BRCA patients into three clusters with significant prognostic differences, namely, cluster 1, cluster 2, and cluster 3. Subsequently, we combined the clinical-pathological data for correlation analysis, and there is a significant correlation between the risk model and the patient’s T and stage. Multivariate Cox regression curve analysis showed that the age of BRCA patients and the risk score of the risk model could be used as independent risk factors in the progression of BRCA. In particular, based on this angiogenesis-related risk model, we have drawn a matching nomogram that can predict the 5-, 7-, and 10-year overall survival rates of BRCA patients. Subsequently, we performed a series of pan-cancer analyses of CNV, SNV, OS, methylation, and immune infiltration for this risk model gene and used GDSC data to explore drug sensitivity. Subsequently, to gain insight into the protein expression of these risk model genes in BRCA, we used the immunohistochemical data in the THPA database for verification. The results showed that the protein expressions of IL18, RUNX1, SCG2, and THY1 molecules in BRCA tissues were significantly higher than those in normal breast tissues, while the protein expressions of PF4 and TNFSF12 molecules in BRCA tissues were significantly lower than those in normal breast tissues. Finally, we conducted multiple GSEA analyses to explore the biological pathways these risk model genes can cross in cancer progression. In summary, we believe that this study can provide valuable data and clues for future studies on angiogenesis in BRCA.

Purpose Lysophosphatidic acid (LPA) is a bioactive molecule which participates in many physical and pathological processes. Although LPA receptor 6 (LPAR6), the last identified LPA receptor, has been reported to have diverse effects in multiple cancers, including breast cancer, its effects and functioning mechanisms are not fully known. Methods Multiple public databases were used to investigate the mRNA expression of LPAR6, its prognostic value, and potential mechanisms in breast cancer. Western blotting was performed to validate the differential expression of LPAR6 in breast cancer tissues and their adjacent tissues. Furthermore, in vitro experiments were used to explore the effects of LPAR6 on breast cancer. Additionally, TargetScan and miRWalk were used to identify potential upstream regulating miRNAs and validated the relationship between miR-27a-3p and LPAR6 via real-time polymerase chain reaction and an in vitro rescue assay. Results LPAR6 was significantly downregulated in breast cancer at transcriptional and translational levels. Decreased LPAR6 expression in breast cancer is significantly correlated with poor overall survival, disease-free survival, and distal metastasis-free survival, particularly for hormone receptor-positive patients, regardless of lymph node metastatic status. In vitro gain and loss-of-function assays indicated that LPAR6 attenuated breast cancer cell proliferation. The analyses of TCGA and METABRIC datasets revealed that LPAR6 may regulate the cell cycle signal pathway. Furthermore, the expression of LPAR6 could be positively regulated by miR-27a-3p. The knockdown of miR-27a-3p increased cell proliferation, and ectopic expression of LPAR6 could partly rescue this phenotype. Conclusion LPAR6 acts as a tumor suppressor in breast cancer and is positively regulated by miR-27a-3p.