Breast cancer is the most prevalent tumour in women. Over two-thirds of breast cancers are estrogen receptor (ER)-positive breast cancers. These breast cancer patients are prone to tamoxifen resistance during breast cancer treatment. There is still a lack of effective clinical treatment for tamoxifen-resistant breast cancer. Dihydrotanshinone I (DHTS) promotes various types of apoptosis in tumour cells. Our network pharmacology study revealed that DHTS has a strong binding capacity to STAT3. Tamoxifen-resistant breast cancers are often accompanied by STAT3 activation. However, there are no reports of DHTS for tamoxifen-resistant breast cancer. Subsequent in vitro experiments also confirmed that DHTS promoted apoptosis in MCF-7-TamR cells, down-regulated the performance of STAT3, pSTAT3, and BCL-2, and activated the production of apoptosisassociated PARP1 and cleaved caspase3. This process could be rescued by overexpression of BCL-2 downstream of STAT3 and was not rescued by either the cytokine EGF or the cytokine PDGF, which promote STAT3 phosphorylation. We hypothesized that DHTS targeting STAT3 promotes apoptosis in MCF-7-TamR cells, mainly by affecting STAT3 phosphorylation. Our research approach described above may provide new ideas for the treatment of tamoxifen-resistant breast cancer.
Breast cancer is one of the leading cancer deaths around the world. Targeted drugs have greatly increased the survival rate of breast cancer patients in recent years. But in some patients, the current regimen is still ineffective. Therefore, more therapeutic targets for treating breast cancer are demanding. The core heterochromatin-related genes of breast cancer were identified by utilizing prognostic survival analysis and multivariate Cox hazard proportional regression analysis. Both breast cancer and adjacent normal tissue were collected and analyzed with western blot and immunohistochemistry. Colony formation assay, CCK8 assay, and EdU assay were used to measure the effect of CBX3 on breast cancer cell growth, wound-healing assay and Transwell assay were used to analyze the effect of CBX3 on breast cancer cell migration and invasion. Flow cytometry assay and western blot were used to study the molecular mechanism of CBX3 in breast cancer. High expression of heterochromatin-related proteins CBX3, H2AFY, and SULF1 showed a poor prognosis in patients in both TCGA dataset and GEO datasets. Western blot demonstrated that the expression level of CBX3 was significantly higher in breast cancer than that in adjacent normal tissues. Colony formation assay, CCK8 assay, and EdU assay showed that the knockdown of CBX3 could significantly inhibit breast cancer cell growth, and the overexpression of CBX3 could promote the growth of breast cancer cells. Transwell assay and wound healing assay showed that knockdown of CBX3 inhibited breast cancer cell migration and invasion, and the overexpression of CBX3 promoted breast cancer cell migration and invasion. Western blot showed that CBX3 might promote breast cancer cell proliferation, invasion, and migration in breast cancer by modulating the ERK1/2 signaling pathway and epithelial-mesenchymal transition (EMT)-related genes. CBX3 was a biomarker of poor prognosis in breast cancer patients. CBX3 promoted the proliferation of breast cancer cells through the ERK signaling pathway, and migration and invasion of breast cancer cells through EMT-related genes. The CBX3/p-ERK1/2 signaling axis might provide a new therapeutic method against breast cancer.
Background: Tumor antigenicity and efficiency of antigen presentation jointly influence tumor immunogenicity, which largely determines the effectiveness of immune checkpoint blockade (ICB). However, the role of altered antigen processing and presentation machinery (APM) in breast cancer (BRCA) has not been fully elucidated. Methods: A series of bioinformatic analyses and machine learning strategies were performed to construct APM-related gene signatures to guide personalized treatment for BRCA patients. A single-sample gene set enrichment analysis (ssGSEA) algorithm and weighted gene co-expression network analysis (WGCNA) were combined to screen for BRCA-specific APM-related genes. The non-negative matrix factorization (NMF) algorithm was used to divide the cohort into different clusters and the fgsea algorithm was applied to investigate the altered signaling pathways. Random survival forest (RSF) and the least absolute shrinkage and selection operator (Lasso) Cox regression analysis were combined to construct an APM-related risk score (APMrs) signature to predict overall survival. Furthermore, a nomogram and decision tree were generated to improve predictive accuracy and risk stratification for individual patients. Based on Tumor Immune Dysfunction and Exclusion (TIDE) method, random forest (RF) and Lasso logistic regression model were combined to establish an APM-related immunotherapeutic response score (APMis). Finally, immune infiltration, immunomodulators, mutational patterns, and potentially applicable drugs were comprehensively analyzed in different APM-related risk groups. Results: In this study, APMrs and APMis showed favorable performances in risk stratification and therapeutic prediction for BRCA patients. APMrs exhibited more powerful prognostic capacity and accurate survival prediction compared to conventional clinicopathological features. APMrs was closely associated with distinct mutational patterns, immune cell infiltration and immunomodulators expression. Furthermore, the two APM-related gene signatures were independently validated in external cohorts with prognosis or immunotherapeutic responses. Potential applicable drugs and targets were further mined in the APMrs-high group. Conclusion: The APM-related gene signatures established in our study could improve the personalized assessment of survival risk and guide ICB decision-making for BRCA patients.
e13092 Background: Breast cancer is the most common malignant tumor in the female population worldwide and has become the disease with the highest cancer-related mortality. Among the molecular subtypes of breast cancer, triple-negative breast cancer accounts for only 15% of primary malignancies, but due to its increasing recurrence, metastasis, and mortality, we need to find new therapeutic targets to address this phenomenon. Analysis from the field of metabolism found that the level of glycolysis in triple-negative breast cancer was significantly higher than that in other cancers. Glycolysis is a common malignant phenotype of cancer, namely the famous Warburg effect. LDHA is the last metabolic enzyme in the glycolytic pathway, and its expression is increased in triple-negative breast cancer. Lactate is the final product of glycolysis, which converts pyruvate to lactate and NADH to NAD+ under the catalysis of LDHA. The acidic tumor microenvironment formed by the accumulation of lactate will not only affect the progression of tumors and the therapeutic effect of anticancer drugs, but also inhibit the function of immune cells. Lactic acid groups can bind to histones and non-histone proteins to produce a new post-translational modification, lactylation. Methods: Breast cancer cells were infected with lentivirus vectors overexpressing or knocking down LDHA, and cell proliferation and cytotoxicity assay, transwell assay and Lactic Acid Content Assay were performed. To further explore the presence of lactylation of LDHA, immunoprecipitation experiments were performed and the modification sites were mutated to examine the enzymatic activity and function of LDHA. Results: In triple negative breast cancer with strong glycolytic metabolic phenotype, altering LDHA level can affect the biological function of breast cancer cells. Secondly, RNA-seq sequencing results showed that LDHA can affect the protein and transcription levels of MEST and CSTA. Finally, the lactylation of histones was also significantly changed after LDHA dysregulated. Reduced levels of LDHA were accompanied by reduced levels of MEST, CSTA, and histone lactylation. In addition, LDHA itself also has lactic acid modification, and mutations in the modification sites can change the enzymatic activity and function of LDHA. Conclusions: The regulatory axis of LDHA-lactate-lactylation has important value and function in the occurrence and development of breast cancer. LDHA regulates the function of some genes by lactate-induced lactylation of histones. In addition, the lactylation of LDHA can alter the enzyme activity, which may be a new therapeutic target for breast cancer.
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